Tuning of "antenna effect" of Eu(III) in ternary systems in aqueous medium through binding with protein.

PubMed

Ghorai, Shyamal Kr; Samanta, Swarna Kamal; Mukherjee, Manini; Saha Sardar, Pinki; Ghosh, Sanjib

2013-02-04

A simple ternary system containing a protein [human serum albumin (HSA)/bovine serum albumin (BSA)], tetracycline hydrochloride (TC), and Eu(III) in suitable aqueous buffer medium at physiological pH (= 7.2) has been shown to exhibit highly efficient "antenna effect" compared to the binary complex of TC with Eu(III) (Eu(3)TC). The ternary system containing E. coli alkaline phosphatase (AP), TC, and Eu(III), however, shows a slight enhancement of Eu(III) emission, although the binding constant of AP with TC is 2 orders of magnitude greater than with BSA/HSA. The enhanced emission of bound TC in the binary systems containing proteins and TC gets quenched in the ternary systems containing HSA/BSA, showing the efficient energy transfer (ET) from TC to Eu(III). Steady state and time-resolved emission studies of each component in all the ternary systems in H(2)O and in D(2)O medium reveal that Eu(III) is very well protected from the O-H oscillator in the ternary system containing HSA/BSA compared to that containing AP. The docking studies locating the binding site of TC in the proteins suggest that TC binds near the surface of AP. In the case of HSA/BSA, TC resides in the interior of the protein resulting in a large shielding effect of Eu(III). The rotational correlation time (θ(c)) determined from the anisotropy decay of bound TC in the complexes and the accessible surface area (ASA) of the ligand in the complexes obtained from the docking studies also support the contention that Eu(3)TC is more exposed to solvent in the case of the ternary system consisting of AP, TC, and Eu(III). The calculated radiative lifetime and the sensitization efficiency ratio of Eu(III) in all the systems clearly demonstrate the protein mediated tuning of "antenna effect" in Eu(III).

Trimeric Association of Hox and TALE Homeodomain Proteins Mediates Hoxb2 Hindbrain Enhancer Activity

PubMed Central

Jacobs, Yakop; Schnabel, Catherine A.; Cleary, Michael L.

1999-01-01

Pbx/exd proteins modulate the DNA binding affinities and specificities of Hox proteins and contribute to the execution of Hox-dependent developmental programs in arthropods and vertebrates. Pbx proteins also stably heterodimerize and bind DNA with Meis and Pknox1-Prep1, additional members of the TALE (three-amino-acid loop extension) superclass of homeodomain proteins that function on common genetic pathways with a subset of Hox proteins. In this study, we demonstrated that Pbx and Meis bind DNA as heterotrimeric complexes with Hoxb1 on a genetically defined Hoxb2 enhancer, r4, that mediates the cross-regulatory transcriptional effects of Hoxb1 in vivo. The DNA binding specificity of the heterotrimeric complex for r4 is mediated by a Pbx-Hox site in conjunction with a distal Meis site, which we showed to be required for ternary complex formation and Meis-enhanced transcription. Formation of heterotrimeric complexes in which all three homeodomains bind their cognate DNA sites is topologically facilitated by the ability of Pbx and Meis to interact through their amino termini and bind DNA without stringent half-site orientation and spacing requirements. Furthermore, Meis site mutation in the Hoxb2 enhancer phenocopies Pbx-Hox site mutation to abrogate enhancer-directed expression of a reporter transgene in the murine embryonic hindbrain, demonstrating that DNA binding by all three proteins is required for trimer function in vivo. Our data provide in vitro and in vivo evidence for the combinatorial regulation of Hox and TALE protein functions that are mediated, in part, by their interdependent DNA binding activities as ternary complexes. As a consequence, Hoxb1 employs Pbx and Meis-related proteins, as a pair of essential cofactors in a higher-order molecular complex, to mediate its transcriptional effects on an endogenous Hox response element. PMID:10373562

Enzyme-like catalysis via ternary complex mechanism: alkoxy-bridged dinuclear cobalt complex mediates chemoselective O-esterification over N-amidation.

PubMed

Hayashi, Yukiko; Santoro, Stefano; Azuma, Yuki; Himo, Fahmi; Ohshima, Takashi; Mashima, Kazushi

2013-04-24

Hydroxy group-selective acylation in the presence of more nucleophilic amines was achieved using acetates of first-row late transition metals, such as Mn, Fe, Co, Cu, and Zn. Among them, cobalt(II) acetate was the best catalyst in terms of reactivity and selectivity. The combination of an octanuclear cobalt carboxylate cluster [Co4(OCOR)6O]2 (2a: R = CF3, 2b: R = CH3, 2c: R = (t)Bu) with nitrogen-containing ligands, such as 2,2'-bipyridine, provided an efficient catalytic system for transesterification, in which an alkoxide-bridged dinuclear complex, Co2(OCO(t)Bu)2(bpy)2(μ2-OCH2-C6H4-4-CH3)2 (10), was successfully isolated as a key intermediate. Kinetic studies and density functional theory calculations revealed Michaelis-Menten behavior of the complex 10 through an ordered ternary complex mechanism similar to dinuclear metallo-enzymes, suggesting the formation of alkoxides followed by coordination of the ester.

Ran-dependent nuclear export mediators: a structural perspective

PubMed Central

Güttler, Thomas; Görlich, Dirk

2011-01-01

Nuclear export is an essential eukaryotic activity. It proceeds through nuclear pore complexes (NPCs) and is mediated by soluble receptors that shuttle between nucleus and cytoplasm. RanGTPase-dependent export mediators (exportins) constitute the largest class of these carriers and are functionally highly versatile. All of these exportins load their substrates in response to RanGTP binding in the nucleus and traverse NPCs as ternary RanGTP–exportin–cargo complexes to the cytoplasm, where GTP hydrolysis leads to export complex disassembly. The different exportins vary greatly in their substrate range. Recent structural studies of both protein- and RNA-specific exporters have illuminated how exportins bind their cargoes, how Ran triggers cargo loading and how export complexes are disassembled in the cytoplasm. Here, we review the current state of knowledge and highlight emerging principles as well as prevailing questions. PMID:21878989

Weighing the evidence for a ternary protein complex mediating A-type K+ currents in neurons.

PubMed

Maffie, Jonathon; Rudy, Bernardo

2008-12-01

The subthreshold-operating A-type K(+) current in neurons (I(SA)) has important roles in the regulation of neuronal excitability, the timing of action potential firing and synaptic integration and plasticity. The channels mediating this current (Kv4 channels) have been implicated in epilepsy, the control of dopamine release, and the regulation of pain plasticity. It has been proposed that Kv4 channels in neurons are ternary complexes of three types of protein: pore forming subunits of the Kv4 subfamily and two types of auxiliary subunits, the Ca(2+) binding proteins KChIPs and the dipeptidyl peptidase-like proteins (DPPLs) DPP6 (also known as DPPX) and DPP10 (4 molecules of each per channel for a total of 12 proteins in the complex). Here we consider the evidence supporting this hypothesis. Kv4 channels in many neurons are likely to be ternary complexes of these three types of protein. KChIPs and DPPLs are required to efficiently traffic Kv4 channels to the plasma membrane and regulate the functional properties of the channels. These proteins may also be important in determining the localization of the channels to specific neuronal compartments, their dynamics, and their response to neuromodulators. A surprisingly large number of additional proteins have been shown to modify Kv4 channels in heterologous expression systems, but their association with native Kv4 channels in neurons has not been properly validated. A critical consideration of the evidence suggests that it is unlikely that association of Kv4 channels with these additional proteins is widespread in the CNS. However, we cannot exclude that some of these proteins may associate with the channels transiently or in specific neurons or neuronal compartments, or that they may associate with the channels in other tissues.

Splenic gene delivery system using self-assembling nano-complex with phosphatidylserine analog.

PubMed

Kurosaki, Tomoaki; Nakasone, Chihiro; Kodama, Yukinobu; Egashira, Kanoko; Harasawa, Hitomi; Muro, Takahiro; Nakagawa, Hiroo; Kitahara, Takashi; Higuchi, Norihide; Nakamura, Tadahiro; Sasaki, Hitoshi

2015-01-01

The recognition of phosphatidylserine on the erythrocyte membrane mediates erythrophagocytosis by resident spleen macrophages. The application of phosphatidylserine to a gene vector may be a novel approach for splenic drug delivery. Therefore, we chose 1,2-dioleoyl-sn-glycero-3-phospho-L-serin (DOPS) as an analogue of phosphatidylserine for splenic gene delivery of plasmid DNA (pDNA). In the present study, we successfully prepared a stable pDNA ternary complex using DOPS and polyethyleneimine (PEI) and evaluated its efficacy and safety. The pDNA/PEI complex had a positive charge and showed high transgene efficacy, although it caused cytotoxicity and agglutination. The addition of DOPS changed the ζ-potential of the pDNA/PEI complex to negative. It is known that anionic complexes are not taken up well by cells. Surprisingly, however, the pDNA/PEI/DOPS complex showed relatively high transgene efficacy in vitro. Fluorescence microscope observation revealed that the pDNA/PEI/DOPS complex internalized the cells while maintaining the complex formation. The injection of the pDNA/PEI complex killed most mice within 24 h at high doses, although all mice in the pDNA/PEI/DOPS complex group survived. The ternary complex with DOPS showed markedly better safety compared with the pDNA/PEI complex. The pDNA/PEI/DOPS complex showed high gene expression selectively in the spleen after intravenous injection into mice. Thus the ternary complex with DOPS can be used to deliver pDNA to the spleen, in which immune cells are abundant. It appears to have an excellent safety level, although further study to determine the mechanism of action is necessary.

Molecular dynamics simulations show altered secondary structure of clawless in binary complex with DNA providing insights into aristaless-clawless-DNA ternary complex formation.

PubMed

Kachhap, Sangita; Priyadarshini, Pragya; Singh, Balvinder

2017-05-01

Aristaless (Al) and clawless (Cll) homeodomains that are involved in leg development in Drosophila melanogaster are known to bind cooperatively to 5'-(T/C)TAATTAA(T/A)(T/A)G-3' DNA sequence, but the mechanism of their binding to DNA is unknown. Molecular dynamics (MD) studies have been carried out on binary, ternary, and reconstructed protein-DNA complexes involving Al, Cll, and DNA along with binding free energy analysis of these complexes. Analysis of MD trajectories of Cll-3A01, binary complex reveals that C-terminal end of helixIII of Cll, unwind in the absence of Al and remains so in reconstructed ternary complex, Cll-3A01-Al. In addition, this change in secondary structure of Cll does not allow it to form protein-protein interactions with Al in the ternary reconstructed complex. However, secondary structure of Cll and its interactions are maintained in other reconstructed ternary complex, Al-3A01-Cll where Cll binds to Al-3A01, binary complex to form ternary complex. These interactions as observed during MD simulations compare well with those observed in ternary crystal structure. Thus, this study highlights the role of helixIII of Cll and protein-protein interactions while proposing likely mechanism of recognition in ternary complex, Al-Cll-DNA.

Fusel Alcohols Regulate Translation Initiation by Inhibiting eIF2B to Reduce Ternary Complex in a Mechanism That May Involve Altering the Integrity and Dynamics of the eIF2B Body

PubMed Central

Taylor, Eleanor J.; Campbell, Susan G.; Griffiths, Christian D.; Reid, Peter J.; Slaven, John W.; Harrison, Richard J.; Sims, Paul F.G.; Pavitt, Graham D.; Delneri, Daniela

2010-01-01

Recycling of eIF2-GDP to the GTP-bound form constitutes a core essential, regulated step in eukaryotic translation. This reaction is mediated by eIF2B, a heteropentameric factor with important links to human disease. eIF2 in the GTP-bound form binds to methionyl initiator tRNA to form a ternary complex, and the levels of this ternary complex can be a critical determinant of the rate of protein synthesis. Here we show that eIF2B serves as the target for translation inhibition by various fusel alcohols in yeast. Fusel alcohols are endpoint metabolites from amino acid catabolism, which signal nitrogen scarcity. We show that the inhibition of eIF2B leads to reduced ternary complex levels and that different eIF2B subunit mutants alter fusel alcohol sensitivity. A DNA tiling array strategy was developed that overcame difficulties in the identification of these mutants where the phenotypic distinctions were too subtle for classical complementation cloning. Fusel alcohols also lead to eIF2α dephosphorylation in a Sit4p-dependent manner. In yeast, eIF2B occupies a large cytoplasmic body where guanine nucleotide exchange on eIF2 can occur and be regulated. Fusel alcohols impact on both the movement and dynamics of this 2B body. Overall, these results confirm that the guanine nucleotide exchange factor, eIF2B, is targeted by fusel alcohols. Moreover, they highlight a potential connection between the movement or integrity of the 2B body and eIF2B regulation. PMID:20444979

Study on effect of L-arginine on solubility and dissolution of Zaltoprofen: Preparation and characterization of binary and ternary cyclodextrin inclusion complexes

NASA Astrophysics Data System (ADS)

Sherje, Atul P.; Patel, Forum; Murahari, Manikanta; Suvarna, Vasanti; Patel, Kavitkumar

2018-02-01

The present study demonstrated the binary and ternary complexes of Zaltoprofen (ZPF) with β-CD and HP-β-CD. The products were characterized using solubility, in vitro dissolution, and DSC studies. The mode of interaction of guest and host was revealed through 1H NMR and FT-IR studies. A significant increase was noticed in the stability constant (Kc) and complexation efficiency (CE) of β-CD and HP-β-CD due to addition of L-Arg in ternary complexes. The ternary complexes showed greater increase in solubility and dissolution of ZPF than binary complexes. Thus, ternary system of ZPF could be an innovative approach for its solubility and dissolution enhancement.

Fluorescence and electron paramagnetic resonance studies of norfloxacin and N-donor mixed-ligand ternary copper(II) complexes: Stability and interaction with SDS micelles

NASA Astrophysics Data System (ADS)

Vignoli Muniz, Gabriel S.; Incio, Jimmy Llontop; Alves, Odivaldo C.; Krambrock, Klaus; Teixeira, Letícia R.; Louro, Sonia R. W.

2018-01-01

The stability of ternary copper(II) complexes of a heterocyclic ligand, L (L being 2,2‧-bipyridine (bipy) or 1,10-phenanthroline (phen)) and the fluorescent antibacterial agent norfloxacin (NFX) as the second ligand was studied at pH 7.4 and different ionic strengths. Fluorescence quenching upon titration of NFX with the binary complexes allowed to obtain stability constants for NFX binding, Kb, as a function of ionic strength. The Kb values vary by more than two orders of magnitude when buffer concentration varies from 0.5 to 100 mM. It was observed that previously synthesized ternary complexes dissociate in buffer according with the obtained stability constants. This shows that equimolar solutions of NFX and binary complexes are equivalent to solutions of synthesized ternary complexes. The interaction of the ternary copper complexes with anionic SDS (sodium dodecyl sulfate) micelles was studied by fluorescence and electron paramagnetic resonance (EPR). Titration of NFX-loaded SDS micelles with the complexes Cu:L allowed to determine the stability constants inside the micelles. Fluorescence quenching demonstrated that SDS micelles increase the stability constants by factors around 50. EPR spectra gave details of the copper(II) local environment, and demonstrated that the structure of the ternary complexes inside SDS micelles is different from that in buffer. Mononuclear ternary complexes formed inside the micelles, while in buffer most ternary complexes are binuclear. The results show that anionic membrane interfaces increase formation of copper fluoroquinolone complexes, which can influence bioavailability, membrane diffusion, and mechanism of action of the antibiotics.

Structural evaluation of crystalline ternary γ-cyclodextrin complex.

PubMed

Higashi, Kenjirou; Ideura, Saori; Waraya, Haruka; Moribe, Kunikazu; Yamamoto, Keiji

2011-01-01

The structure of a crystalline γ-cyclodextrin (γ-CD) ternary complex containing salicylic acid (SA) and flurbiprofen (FBP) prepared by sealed heating was investigated. FBP/γ-CD inclusion complex was prepared by coprecipitation; its molar ratio was determined as 1/1. Powder X-ray diffraction measurements showed that the molecular packing of γ-CD changed from hexagonal to monoclinic columnar form by sealed heating of SA with dried FBP/γ-CD inclusion complex, indicating ternary complex formation. The stoichiometry of SA/FBP/γ-CD was estimated as 2/1/1. Solid-state transformation of γ-CD molecular packing upon water vapor adsorption and desorption was irreversible for this ternary complex, in contrast to the reversible transition for the FBP/γ-CD inclusion complex. The ternary complex contained one FBP molecule in the cavity of γ-CD and two SA molecules in the intermolecular space between neighboring γ-CD column stacks. Infrared and (13) C solid-state NMR spectroscopies revealed that the molecular states of SA and FBP changed upon ternary complex formation. In the complex, dimer FBP molecules were sandwiched between two γ-CD molecules whereas each monomer SA molecule was present in the intermolecular space of γ-CD. Ternary complex formation was also observed for other drug-guest systems using naproxen and ketoprofen. Thus, the complex can be used to formulate variety of drugs. Copyright © 2010 Wiley-Liss, Inc. and the American Pharmacists Association

Elongation factor Ts directly facilitates the formation and disassembly of the Escherichia coli elongation factor Tu·GTP·aminoacyl-tRNA ternary complex.

PubMed

Burnett, Benjamin J; Altman, Roger B; Ferrao, Ryan; Alejo, Jose L; Kaur, Navdep; Kanji, Joshua; Blanchard, Scott C

2013-05-10

Aminoacyl-tRNA (aa-tRNA) enters the ribosome in a ternary complex with the G-protein elongation factor Tu (EF-Tu) and GTP. EF-Tu·GTP·aa-tRNA ternary complex formation and decay rates are accelerated in the presence of the nucleotide exchange factor elongation factor Ts (EF-Ts). EF-Ts directly facilitates the formation and disassociation of ternary complex. This system demonstrates a novel function of EF-Ts. Aminoacyl-tRNA enters the translating ribosome in a ternary complex with elongation factor Tu (EF-Tu) and GTP. Here, we describe bulk steady state and pre-steady state fluorescence methods that enabled us to quantitatively explore the kinetic features of Escherichia coli ternary complex formation and decay. The data obtained suggest that both processes are controlled by a nucleotide-dependent, rate-determining conformational change in EF-Tu. Unexpectedly, we found that this conformational change is accelerated by elongation factor Ts (EF-Ts), the guanosine nucleotide exchange factor for EF-Tu. Notably, EF-Ts attenuates the affinity of EF-Tu for GTP and destabilizes ternary complex in the presence of non-hydrolyzable GTP analogs. These results suggest that EF-Ts serves an unanticipated role in the cell of actively regulating the abundance and stability of ternary complex in a manner that contributes to rapid and faithful protein synthesis.

Effects of Chain Length and Degree of Unsaturation of Fatty Acids on Structure and in Vitro Digestibility of Starch-Protein-Fatty Acid Complexes.

PubMed

Zheng, Mengge; Chao, Chen; Yu, Jinglin; Copeland, Les; Wang, Shuo; Wang, Shujun

2018-02-28

The effects of chain length and degree of unsaturation of fatty acids (FAs) on structure and in vitro digestibility of starch-protein-FA complexes were investigated in model systems. Studies with the rapid visco analyzer (RVA) showed that the formation of ternary complex resulted in higher viscosities than those of binary complex during the cooling and holding stages. The results of differential scanning calorimetry (DSC), Raman, and X-ray diffraction (XRD) showed that the structural differences for ternary complexes were much less than those for binary complexes. Starch-protein-FA complexes presented lower in vitro enzymatic digestibility compared with starch-FAs complexes. We conclude that shorter chain and lower unsaturation FAs favor the formation of ternary complexes but decrease the thermal stability of these complexes. FAs had a smaller effect on the ordered structures of ternary complexes than on those of binary complexes and little effect on enzymatic digestibility of both binary and ternary complexes.

A biomimetic pH-responsive polymer directs endosomal release and intracellular delivery of an endocytosed antibody complex.

PubMed

Lackey, Chantal A; Press, Oliver W; Hoffman, Allan S; Stayton, Patrick S

2002-01-01

Poly(propylacrylic acid) (PPAAc) is a synthetic pH-responsive polymer that has been shown to disrupt cell membranes at low pH values typical of the endosome, but not at physiological pH, suggesting its use as an endosomal-releasing agent [Murthy et al. J. Controlled Release 61, 137-43]. We have constructed an antibody-targeted biotherapeutic model to investigate whether PPAAc can enhance intracellular trafficking of proteins to the cytoplasm. A ternary complex composed of a biotinylated anti-CD3 antibody, streptavidin, and biotinylated PPAAc was fluorescently labeled, and its intracellular fate was analyzed by confocal microscopy, flow cytometry, and quantitative western blotting of cell fractionates. The 64.1 anti-CD3 antibody was previously shown to direct receptor-mediated endocytosis in the Jurkat T-cell lymphoma cell line and was rapidly trafficked from the endosome to the lysosomal compartment. The antibody-streptavidin complex was also rapidly internalized to the endosomal/lysosomal compartment and retained there, as evidenced by punctate regions of fluorescence observed by confocal fluorescence microscopy. In samples containing the ternary complex of antibody, streptavidin, and PPAAc-biotin, diffuse fluorescence in the cytoplasm was observed, indicating that PPAAc enhanced translocation to the cytoplasm. This was confirmed by western blotting analysis of the isolated cytoplasm. Flow cytometry results demonstrated that neither streptavidin nor PPAAc caused nonspecific uptake of the complex, nor did they inhibit antibody-mediated endocytosis. The striking enhancement of protein delivery to the cytoplasm by complexed PPAAc suggests that this polymer could provide a new delivery agent for therapeutic, vaccine, and diagnostics development.

Effect of guest drug character encapsulated in the cavity and intermolecular spaces of γ-cyclodextrins on the dissolution property of ternary γ-cyclodextrin complex.

PubMed

Liu, Nan; Higashi, Kenjirou; Ueda, Keisuke; Moribe, Kunikazu

2017-10-15

Various ternary Guest 2/(Guest 1/γ-cyclodextrin (CD)) complexes were prepared using a cogrinding and subsequent heating method, wherein Guest 1 was incorporated in the cavity of γ-CD and Guest 2 was incorporated into the intermolecular spaces between γ-CD columns. Dissolution fluxes of Guest 1 and Guest 2 from all ternary complexes were almost identical. The dissolution flux of flurbiprofen (Guest 1) from the ternary complexes depended on the solubility of Guest 2 drugs (naproxen

Structural characterization and bioavailability of ternary nanoparticles consisting of amylose, α-linoleic acid and β-lactoglobulin complexed with naringin.

PubMed

Feng, Tao; Wang, Ke; Liu, Fangfang; Ye, Ran; Zhu, Xiao; Zhuang, Haining; Xu, Zhimin

2017-06-01

Naringin is a bioflavonoid that is rich in citrus plants and possesses enormous health benefits. However, the use of naringin as a nutraceutical is significantly limited by its low bioavailability. In this study, a novel water-soluble ternary nanoparticle material consisting of amylose, α-linoleic acid and β-lactoglobulin was developed to encapsulate naringin to improve its bioavailability. The physicochemical characteristics of the ternary nanoparticle-naringin inclusion complex were analysed by ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), high-resolution transmission electron microscopy (TEM), X-ray diffractometry (XRD) and particle size distribution. The results confirmed the formation of the ternary nanoparticle-naringin inclusion complex. The encapsulation efficiency (EE) and loading content (LC) of the ternary nanoparticle-naringin inclusion complex were 78.73±4.17% and 14.51±3.43%, respectively. In addition, the results of the ternary nanoparticle-naringin inclusion complex in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) demonstrated that naringin can be gradually released from the complex. In conclusion, ternary nanoparticles are considered promising carriers to effectively improve the bioavailability of naringin. Copyright © 2017 Elsevier B.V. All rights reserved.

Integration of growth factor signals at the c-fos serum response element.

PubMed

Price, M A; Hill, C; Treisman, R

1996-04-29

A transcription factor ternary complex composed of serum response factor (SRF) and a second factor, ternary complex factor (TCF), mediates the response of the c-fos Serum Response Element to growth factors and mitogens. In NIH3T3 fibroblasts, TCF binding is required for transcriptional activation by the SRE in response to activation of the Ras-Raf-ERK pathway. We compared the properties of three members of the TCF family, Elk-1, SAP-1 and SAP-2 (ERP/NET). Although all the proteins contain sequences required for ternary complex formation with SRF, only Elk-1 and SAP-1 appear to interact with the c-fos SRE efficiently in vivo. Each TCF contains a C-terminal activation domain capable of transcriptional activation in response to activation of the Ras-Raf-ERK pathway, and this is dependent on the integrity of S/T-P motifs conserved between all the TCF family members. In contrast, activation of the SRE by whole serum and the mitogenic phospholipid LPA requires SRF binding alone. Constitutively activated members of the Rho subfamily of Ras-like GTPases are also capable of inducing activation of the SRE in the absence of TCF; unlike activated Ras itself, these proteins do not activate the TCFs in NIH3T3 cells. At the SRE, SRF- and TCF-linked signalling pathways act synergistically to potentiate transcription.

Ternary iron(II) complex with an emissive imidazopyridine arm from Schiff base cyclizations and its oxidative DNA cleavage activity.

PubMed

Mukherjee, Arindam; Dhar, Shanta; Nethaji, Munirathinam; Chakravarty, Akhil R

2005-01-21

The ternary iron(II) complex [Fe(L')(L")](PF6)3(1) as a synthetic model for the bleomycins, where L' and L" are formed from metal-mediated cyclizations of N,N'-(2-hydroxypropane-1,3-diyl)bis(pyridine-2-aldimine)(L), is synthesized and structurally characterized by X-ray crystallography. In the six-coordinate iron(ii) complex, ligands L' and L" show tetradentate and bidentate chelating modes of bonding. Ligand L' is formed from an intramolecular attack of the alcoholic OH group of L to one imine moiety leading to the formation of a stereochemically constrained five-membered ring. Ligand L" which is formed from an intermolecular reaction involving one imine moiety of L and pyridine-2-carbaldehyde has an emissive cationic imidazopyridine pendant arm. The complex binds to double-stranded DNA in the minor groove giving a Kapp value of 4.1 x 10(5) M(-1) and displays oxidative cleavage of supercoiled DNA in the presence of H2O2 following a hydroxyl radical pathway. The complex also shows photo-induced DNA cleavage activity on UV light exposure involving formation of singlet oxygen as the reactive species.

The ribonuclease polynucleotide phosphorylase can interact with small regulatory RNAs in both protective and degradative modes.

PubMed

Bandyra, Katarzyna J; Sinha, Dhriti; Syrjanen, Johanna; Luisi, Ben F; De Lay, Nicholas R

2016-03-01

In all bacterial species examined thus far, small regulatory RNAs (sRNAs) contribute to intricate patterns of dynamic genetic regulation. Many of the actions of these nucleic acids are mediated by well-characterized chaperones such as the Hfq protein, but genetic screens have also recently identified the 3'-to-5' exoribonuclease polynucleotide phosphorylase (PNPase) as an unexpected stabilizer and facilitator of sRNAs in vivo. To understand how a ribonuclease might mediate these effects, we tested the interactions of PNPase with sRNAs and found that the enzyme can readily degrade these nucleic acids in vitro but, nonetheless, copurifies from cell extracts with the same sRNAs without discernible degradation or modification to their 3' ends, suggesting that the associated RNA is protected against the destructive activity of the ribonuclease. In vitro, PNPase, Hfq, and sRNA can form a ternary complex in which the ribonuclease plays a nondestructive, structural role. Such ternary complexes might be formed transiently in vivo, but could help to stabilize particular sRNAs and remodel their population on Hfq. Taken together, our results indicate that PNPase can be programmed to act on RNA in either destructive or stabilizing modes in vivo and may form complex, protective ribonucleoprotein assemblies that shape the landscape of sRNAs available for action. © 2016 Bandyra et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

The ribonuclease polynucleotide phosphorylase can interact with small regulatory RNAs in both protective and degradative modes

PubMed Central

Bandyra, Katarzyna J.; Sinha, Dhriti; Syrjanen, Johanna; Luisi, Ben F.; De Lay, Nicholas R.

2016-01-01

In all bacterial species examined thus far, small regulatory RNAs (sRNAs) contribute to intricate patterns of dynamic genetic regulation. Many of the actions of these nucleic acids are mediated by well-characterized chaperones such as the Hfq protein, but genetic screens have also recently identified the 3′-to-5′ exoribonuclease polynucleotide phosphorylase (PNPase) as an unexpected stabilizer and facilitator of sRNAs in vivo. To understand how a ribonuclease might mediate these effects, we tested the interactions of PNPase with sRNAs and found that the enzyme can readily degrade these nucleic acids in vitro but, nonetheless, copurifies from cell extracts with the same sRNAs without discernible degradation or modification to their 3′ ends, suggesting that the associated RNA is protected against the destructive activity of the ribonuclease. In vitro, PNPase, Hfq, and sRNA can form a ternary complex in which the ribonuclease plays a nondestructive, structural role. Such ternary complexes might be formed transiently in vivo, but could help to stabilize particular sRNAs and remodel their population on Hfq. Taken together, our results indicate that PNPase can be programmed to act on RNA in either destructive or stabilizing modes in vivo and may form complex, protective ribonucleoprotein assemblies that shape the landscape of sRNAs available for action. PMID:26759452

Extraction and characterization of ternary complexes between natural organic matter, cations, and oxyanions from a natural soil.

PubMed

Peel, Hannah R; Martin, David P; Bednar, Anthony J

2017-06-01

Natural organic matter (NOM) can have a significant influence on the mobility and fate of inorganic oxyanions, such as arsenic and selenium, in the environment. There is evidence to suggest that interactions between NOM and these oxyanions are facilitated by bridging cations (primarily Fe 3+ ) through the formation of ternary complexes. Building on previous work characterizing ternary complexes formed in the laboratory using purified NOM, this study describes the extraction and characterization of intact ternary complexes directly from a soil matrix. The complexes are stable to the basic extraction conditions (pH 12) and do not appear to change when the pH of the extract is adjusted back to neutral. The results suggest that ternary complexes between NOM, cations, and inorganic oxyanions exist in natural soils and could play a role in the speciation of inorganic oxyanions in environmental matrices. Published by Elsevier Ltd.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yanli; Juranek, Stefan; Li, Haitao

Here we report on a 3.0 {angstrom} crystal structure of a ternary complex of wild-type Thermus thermophilus argonaute bound to a 5'-phosphorylated 21-nucleotide guide DNA and a 20-nucleotide target RNA containing cleavage-preventing mismatches at the 10-11 step. The seed segment (positions 2 to 8) adopts an A-helical-like Watson-Crick paired duplex, with both ends of the guide strand anchored in the complex. An arginine, inserted between guide-strand bases 10 and 11 in the binary complex, locking it in an inactive conformation, is released on ternary complex formation. The nucleic-acid-binding channel between the PAZ- and PIWI-containing lobes of argonaute widens on formationmore » of a more open ternary complex. The relationship of structure to function was established by determining cleavage activity of ternary complexes containing position-dependent base mismatch, bulge and 2'-O-methyl modifications. Consistent with the geometry of the ternary complex, bulges residing in the seed segments of the target, but not the guide strand, were better accommodated and their complexes were catalytically active.« less

Mechanical properties of bulk graphene oxide/poly(acrylic acid)/poly(ethylenimine) ternary polyelectrolyte complex.

PubMed

Duan, Yipin; Wang, Chao; Zhao, Mengmeng; Vogt, Bryan D; Zacharia, Nicole S

2018-05-30

Ternary complexes formed in a single pot process through the mixing of cationic (branched polyethylenimine, BPEI) and anionic (graphene oxide, GO, and poly(acrylic acid), PAA) aqueous solutions exhibit superior mechanical performance in comparison to their binary analogs. The composition of the ternary complex can be simply tuned through the composition of the anionic solution, which influences the water content and mechanical properties of the complex. Increasing the PAA content in the complex decreases the overall water content due to improved charge compensation with the BPEI, but this change also significantly improves the toughness of the complex. Ternary complexes containing ≤32 wt% PAA were too brittle to generate samples for tensile measurements, while extension in excess of 250% could be reached with 57 wt% PAA. From this work, the influence of GO and PAA on the mechanical properties of GO/PAA/BPEI complexes were elucidated with GO sheets acting to restrain the viscous flow and improve the mechanical strength at low loading (<12.6 wt%) and PAA more efficiently complexes with BPEI than GO to generate a less swollen and stronger network. This combination overcomes the brittle nature of GO-BPEI complexes and viscous creep of PAA-BPEI complexes. Ternary nanocomposite complexes appear to provide an effective route to toughen and strengthen bulk polyelectrolyte complexes.

Elongation Factor Ts Directly Facilitates the Formation and Disassembly of the Escherichia coli Elongation Factor Tu·GTP·Aminoacyl-tRNA Ternary Complex*

PubMed Central

Burnett, Benjamin J.; Altman, Roger B.; Ferrao, Ryan; Alejo, Jose L.; Kaur, Navdep; Kanji, Joshua; Blanchard, Scott C.

2013-01-01

Aminoacyl-tRNA enters the translating ribosome in a ternary complex with elongation factor Tu (EF-Tu) and GTP. Here, we describe bulk steady state and pre-steady state fluorescence methods that enabled us to quantitatively explore the kinetic features of Escherichia coli ternary complex formation and decay. The data obtained suggest that both processes are controlled by a nucleotide-dependent, rate-determining conformational change in EF-Tu. Unexpectedly, we found that this conformational change is accelerated by elongation factor Ts (EF-Ts), the guanosine nucleotide exchange factor for EF-Tu. Notably, EF-Ts attenuates the affinity of EF-Tu for GTP and destabilizes ternary complex in the presence of non-hydrolyzable GTP analogs. These results suggest that EF-Ts serves an unanticipated role in the cell of actively regulating the abundance and stability of ternary complex in a manner that contributes to rapid and faithful protein synthesis. PMID:23539628

mTORC1 and CK2 coordinate ternary and eIF4F complex assembly

PubMed Central

Gandin, Valentina; Masvidal, Laia; Cargnello, Marie; Gyenis, Laszlo; McLaughlan, Shannon; Cai, Yutian; Tenkerian, Clara; Morita, Masahiro; Balanathan, Preetika; Jean-Jean, Olivier; Stambolic, Vuk; Trost, Matthias; Furic, Luc; Larose, Louise; Koromilas, Antonis E.; Asano, Katsura; Litchfield, David; Larsson, Ola; Topisirovic, Ivan

2016-01-01

Ternary complex (TC) and eIF4F complex assembly are the two major rate-limiting steps in translation initiation regulated by eIF2α phosphorylation and the mTOR/4E-BP pathway, respectively. How TC and eIF4F assembly are coordinated, however, remains largely unknown. We show that mTOR suppresses translation of mRNAs activated under short-term stress wherein TC recycling is attenuated by eIF2α phosphorylation. During acute nutrient or growth factor stimulation, mTORC1 induces eIF2β phosphorylation and recruitment of NCK1 to eIF2, decreases eIF2α phosphorylation and bolsters TC recycling. Accordingly, eIF2β mediates the effect of mTORC1 on protein synthesis and proliferation. In addition, we demonstrate a formerly undocumented role for CK2 in regulation of translation initiation, whereby CK2 stimulates phosphorylation of eIF2β and simultaneously bolsters eIF4F complex assembly via the mTORC1/4E-BP pathway. These findings imply a previously unrecognized mode of translation regulation, whereby mTORC1 and CK2 coordinate TC and eIF4F complex assembly to stimulate cell proliferation. PMID:27040916

Androgen-Induced Cell Migration: Role of Androgen Receptor/Filamin A Association

PubMed Central

Castoria, Gabriella; D'Amato, Loredana; Ciociola, Alessandra; Giovannelli, Pia; Giraldi, Tiziana; Sepe, Leandra; Paolella, Giovanni; Barone, Maria Vittoria; Migliaccio, Antimo; Auricchio, Ferdinando

2011-01-01

Background Androgen receptor (AR) controls male morphogenesis, gametogenesis and prostate growth as well as development of prostate cancer. These findings support a role for AR in cell migration and invasiveness. However, the molecular mechanism involved in AR-mediated cell migration still remains elusive. Methodology/Principal Findings Mouse embryo NIH3T3 fibroblasts and highly metastatic human fibrosarcoma HT1080 cells harbor low levels of transcriptionally incompetent AR. We now report that, through extra nuclear action, AR triggers migration of both cell types upon stimulation with physiological concentrations of the androgen R1881. We analyzed the initial events leading to androgen-induced cell migration and observed that challenging NIH3T3 cells with 10 nM R1881 rapidly induces interaction of AR with filamin A (FlnA) at cytoskeleton. AR/FlnA complex recruits integrin beta 1, thus activating its dependent cascade. Silencing of AR, FlnA and integrin beta 1 shows that this ternary complex controls focal adhesion kinase (FAK), paxillin and Rac, thereby driving cell migration. FAK-null fibroblasts migrate poorly and Rac inhibition by EHT impairs motility of androgen-treated NIH3T3 cells. Interestingly, FAK and Rac activation by androgens are independent of each other. Findings in human fibrosarcoma HT1080 cells strengthen the role of Rac in androgen signaling. The Rac inhibitor significantly impairs androgen-induced migration in these cells. A mutant AR, deleted of the sequence interacting with FlnA, fails to mediate FAK activation and paxillin tyrosine phosphorylation in androgen-stimulated cells, further reinforcing the role of AR/FlnA interaction in androgen-mediated motility. Conclusions/Significance The present report, for the first time, indicates that the extra nuclear AR/FlnA/integrin beta 1 complex is the key by which androgen activates signaling leading to cell migration. Assembly of this ternary complex may control organ development and prostate cancer metastasis. PMID:21359179

In vitro and in vivo gene delivery using chitosan/hyaluronic acid nanoparticles: Influences of molecular mass of hyaluronic acid and lyophilization on transfection efficiency.

PubMed

Sato, Toshinori; Nakata, Mitsuhiro; Yang, Zhihong; Torizuka, Yu; Kishimoto, Satoko; Ishihara, Masayuki

2017-08-01

Lyophilization is an effective method for preserving nonviral gene vectors. To improve the stability and transgene expression of lyophilized plasmid DNA (pDNA) complexes, we coated the surfaces of pDNA/chitosan complexes with hyaluronic acid (HA) of varying molecular masses. The transgene expression of pDNA/chitosan/HA ternary complexes was characterized in vitro and in vivo. pDNA complexes were lyophilized overnight and the resultant products with spongy, porous consistencies were stored at -30, 4 or 25°C for 2 weeks. Rehydrated complexes were characterized using gel retardation assays, aiming to confirm complex formation, measure particle size and evaluate zeta potential, as well as conduct luciferase gene reporter assays. The anti-tumor effects of pDNA ternary complexes were evaluated using suicide gene (pTK) coding thymidine kinase in Huh7-implanted mice. Transfection efficiencies of pDNA/chitosan/HA ternary complexes were dependent on the average molecular masses of HA. The coating of pDNA/chitosan complexes with HA maintained the cellular transfection efficiencies of lyophilized pDNA ternary complexes. Furthermore, intratumoral injection of lyophilized, rehydrated pDNA ternary complexes into tumor-bearing mice showed a significant suppression of tumor growth. The coating of pDNA/chitosan complexes with high-molecular-weight HA augmented the stability and cellular transfection ability of the complexes after lyophilization-rehydration. Copyright © 2017 John Wiley & Sons, Ltd.

Self-assembling HA/PEI/dsRNA-p21 ternary complexes for CD44 mediated small active RNA delivery to colorectal cancer.

PubMed

Feng, Chen-Lin; Han, Yan-Xing; Guo, Hui-Hui; Ma, Xiao-Lei; Wang, Zhi-Qiang; Wang, Lu-Lu; Zheng, Wen-Sheng; Jiang, Jian-Dong

2017-11-01

Our previous work proved that sequence specific double strand RNA (dsRNA-p21) effectively activated p21 gene expression of colorectal cancer (CRC) cells and consequently suppressed CRC growth. However, efficient delivery system is a significant challenge to achieve sufficient therapy. In this study, a self-assembled HA/PEI/dsRNA-p21 ternary complex (TC-dsRNA-p21) was developed for the tumor-target delivery of dsRNA-p21 into CRC cells. Hyaluronic acid (HA) was introduced to shield the PEI/dsRNA-p21 binary complexes (BC-dsRNA-p21) for reducing the cytotoxicity of PEI and for increasing the tumor-targeted intracellular uptake by cancer cells through HA-CD44 mediated endocytosis. Comparing to the BC-dsRNA-p21, the TC-dsRNA-p21 showed increase in size, decrease in zeta potential, low cytotoxicity as well as high stability in physiological conditions due to the anionic shielding. Confocal microscopy analysis and flow cytometry confirmed that TC-dsRNA-p21 had high transfection efficiency in the CD44-abundant Lovo cells, as compared with binary complex. In vitro physiological experiment showed that, comparing to the control group, the TC-dsRNA-p21 effectively activated the expression of p21 mRNA and P21 protein, causing blockage of cell cycle at G 0 /G 1 phase and suppression of cancer cell proliferation as well as colony formation. Furthermore, in vivo distribution experiment demonstrated that the TC-dsRNA-p21 could effectively accumulate at rectal wall for up to 10 h, following in situ application. These findings indicated that TC-dsRNA-p21 might hold great potential for delivering dsRNA-p21 to treat CRC.

Characterization of U(VI)-carbonato ternary complexes on hematite: EXAFS and electrophoretic mobility measurements

USGS Publications Warehouse

Bargar, John R.; Reitmeyer, Rebecca; Lenhart, John J.; Davis, James A.

2000-01-01

We have measured U(VI) adsorption on hematite using EXAFS spectroscopy and electrophoresis under conditions relevant to surface waters and aquifers (0.01 to 10 μM dissolved uranium concentrations, in equilibrium with air, pH 4.5 to 8.5). Both techniques suggest the existence of anionic U(VI)-carbonato ternary complexes. Fits to EXAFS spectra indicate that U(VI) is simultaneously coordinated to surface FeO6 octahedra and carbonate (or bicarbonate) ligands in bidentate fashions, leading to the conclusion that the ternary complexes have an inner-sphere metal bridging (hematite-U(VI)-carbonato) structure. Greater than or equal to 50% of adsorbed U(VI) was comprised of monomeric hematite-U(VI)-carbonato ternary complexes, even at pH 4.5. Multimeric U(VI) species were observed at pH ≥ 6.5 and aqueous U(VI) concentrations approximately an order of magnitude more dilute than the solubility of crystalline β-UO2(OH)2. Based on structural constraints, these complexes were interpreted as dimeric hematite-U(VI)-carbonato ternary complexes. These results suggest that Fe-oxide-U(VI)-carbonato complexes are likely to be important transport-limiting species in oxic aquifers throughout a wide range of pH values.

A ternary metal binding site in the C2 domain of phosphoinositide-specific phospholipase C-delta1.

PubMed

Essen, L O; Perisic, O; Lynch, D E; Katan, M; Williams, R L

1997-03-11

We have determined the crystal structures of complexes of phosphoinositide-specific phospholipase C-delta1 from rat with calcium, barium, and lanthanum at 2.5-2.6 A resolution. Binding of these metal ions is observed in the active site of the catalytic TIM barrel and in the calcium binding region (CBR) of the C2 domain. The C2 domain of PLC-delta1 is a circularly permuted topological variant (P-variant) of the synaptotagmin I C2A domain (S-variant). On the basis of sequence analysis, we propose that both the S-variant and P-variant topologies are present among other C2 domains. Multiple adjacent binding sites in the C2 domain were observed for calcium and the other metal/enzyme complexes. The maximum number of binding sites observed was for the calcium analogue lanthanum. This complex shows an array-like binding of three lanthanum ions (sites I-III) in a crevice on one end of the C2 beta-sandwich. Residues involved in metal binding are contained in three loops, CBR1, CBR2, and CBR3. Sites I and II are maintained in the calcium and barium complexes, whereas sites II and III coincide with a binary calcium binding site in the C2A domain of synaptotagmin I. Several conformers for CBR1 are observed. The conformation of CBR1 does not appear to be strictly dependent on metal binding; however, metal binding may stabilize certain conformers. No significant structural changes are observed for CBR2 or CBR3. The surface of this ternary binding site provides a cluster of freely accessible liganding positions for putative phospholipid ligands of the C2 domain. It may be that the ternary metal binding site is also a feature of calcium-dependent phospholipid binding in solution. A ternary metal binding site might be a conserved feature among C2 domains that contain the critical calcium ligands in their CBR's. The high cooperativity of calcium-mediated lipid binding by C2 domains described previously is explained by this novel type of calcium binding site.

Ternary complexes of folate-PEG-appended dendrimer (G4)/α-cyclodextrin conjugate, siRNA and low-molecular-weight polysaccharide sacran as a novel tumor-selective siRNA delivery system.

PubMed

Ohyama, Ayumu; Higashi, Taishi; Motoyama, Keiichi; Arima, Hidetoshi

2017-06-01

We previously developed a tumor-selective siRNA carrier by preparing polyamidoamine dendrimer (generation 4, G4) conjugates with α-cyclodextrin and folate-polyethylene glycol (Fol-PαC (G4)). In the present study, we developed ternary complexes of Fol-PαC (G4)/siRNA with low-molecular-weight-sacrans to achieve more effective siRNA transfer activity. Among the different molecular-weight sacrans, i.e. sacran 100, 1000 and 10,000 (MW 44,889Da, 943,692Da and 1,488,281Da, respectively), sacran 100 significantly increased the cellular uptake and the RNAi effects of Fol-PαC (G4)/siRNA binary complex with negligible cytotoxicity in KB cells (folate receptor-α positive cells). In addition, the ζ-potential and particle size of Fol-PαC (G4)/siRNA complex were decreased by the ternary complexation with sacran 100. Importantly, the in vivo RNAi effect of the ternary complex after the intravenous administration to tumor-bearing BALB/c mice was significantly higher than that of the binary complex. In conclusion, Fol-PαC (G4)/siRNA/sacran 100 ternary complex has a potential as a novel tumor-selective siRNA delivery system. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhanced photocatalytic activity of graphitic carbon nitride/carbon nanotube/Bi2WO6 ternary Z-scheme heterojunction with carbon nanotube as efficient electron mediator.

PubMed

Jiang, Deli; Ma, Wanxia; Xiao, Peng; Shao, Leqiang; Li, Di; Chen, Min

2018-02-15

All-solid-state Z-scheme heterojunction has attracted much attention in photocatalytic field because of its strong ability in charge separation and transfer. In the present study, all-solid-state ternary Z-scheme heterojunction constructed by graphitic carbon nitride (CN) nanosheet, carbon nanotube (CNT), and Bi 2 WO 6 (BWO) nanosheet, in which CNT was employed as the electron mediator. The CN/CNT/BWO ternary Z-scheme heterojunction shows the enhanced photocatalytic activity towards the degradation of tetracycline hydrochloride (TC) as compared to the pristine g-C 3 N 4 , Bi 2 WO 6 , CNT/BWO, CNT/CN, and CN/BWO. The significantly improved photocatalytic activity can be mainly ascribed to the formed CNT-mediated Z-scheme heterojunction, which facilitates the separation and transfer of photogenerated electron-hole pairs. Our work provides a rational design of all-solid-state Z-scheme heterojunction with CNT as the electron mediator for highly efficient photocatalysis. Copyright © 2017 Elsevier Inc. All rights reserved.

A Stimulation Function of Synaptotagmin-1 in Ternary SNARE Complex Formation Dependent on Munc18 and Munc13

PubMed Central

Li, Yun; Wang, Shen; Li, Tianzhi; Zhu, Le; Xu, Yuanyuan; Ma, Cong

2017-01-01

The Ca2+ sensor synaptotagmin-1 (Syt1) plays an essential function in synaptic exocytosis. Recently, Syt1 has been implicated in synaptic vesicle priming, a maturation step prior to Ca2+-triggered membrane fusion that is believed to involve formation of the ternary SNARE complex and require priming proteins Munc18-1 and Munc13-1. However, the mechanisms of Syt1 in synaptic vesicle priming are still unclear. In this study, we found that Syt1 stimulates the transition from the Munc18-1/syntaxin-1 complex to the ternary SNARE complex catalyzed by Munc13-1. This stimulation can be further enhanced in a membrane-containing environment. Further, we showed that Syt1, together with Munc18-1 and Munc13-1, stimulates trans ternary SNARE complex formation on membranes in a manner resistant to disassembly factors NSF and α-SNAP. Disruption of a proposed Syt1/SNARE binding interface strongly abrogated the stimulation function of Syt1. Our results suggest that binding of Syt1 to an intermediate SNARE assembly with Munc18-1 and Munc13-1 is critical for the stimulation function of Syt1 in ternary SNARE complex formation, and this stimulation may underlie the priming function of Syt1 in synaptic exocytosis. PMID:28860966

The kinase activity of the Ser/Thr kinase BUB1 promotes TGF-β signaling.

PubMed

Nyati, Shyam; Schinske-Sebolt, Katrina; Pitchiaya, Sethuramasundaram; Chekhovskiy, Katerina; Chator, Areeb; Chaudhry, Nauman; Dosch, Joseph; Van Dort, Marcian E; Varambally, Sooryanarayana; Kumar-Sinha, Chandan; Nyati, Mukesh Kumar; Ray, Dipankar; Walter, Nils G; Yu, Hongtao; Ross, Brian Dale; Rehemtulla, Alnawaz

2015-01-06

Transforming growth factor-β (TGF-β) signaling regulates cell proliferation and differentiation, which contributes to development and disease. Upon binding TGF-β, the type I receptor (TGFBRI) binds TGFBRII, leading to the activation of the transcription factors SMAD2 and SMAD3. Using an RNA interference screen of the human kinome and a live-cell reporter for TGFBR activity, we identified the kinase BUB1 (budding uninhibited by benzimidazoles-1) as a key mediator of TGF-β signaling. BUB1 interacted with TGFBRI in the presence of TGF-β and promoted the heterodimerization of TGFBRI and TGFBRII. Additionally, BUB1 interacted with TGFBRII, suggesting the formation of a ternary complex. Knocking down BUB1 prevented the recruitment of SMAD3 to the receptor complex, the phosphorylation of SMAD2 and SMAD3 and their interaction with SMAD4, SMAD-dependent transcription, and TGF-β-mediated changes in cellular phenotype including epithelial-mesenchymal transition (EMT), migration, and invasion. Knockdown of BUB1 also impaired noncanonical TGF-β signaling mediated by the kinases AKT and p38 MAPK (mitogen-activated protein kinase). The ability of BUB1 to promote TGF-β signaling depended on the kinase activity of BUB1. A small-molecule inhibitor of the kinase activity of BUB1 (2OH-BNPP1) and a kinase-deficient mutant of BUB1 suppressed TGF-β signaling and formation of the ternary complex in various normal and cancer cell lines. 2OH-BNPP1 administration to mice bearing lung carcinoma xenografts reduced the amount of phosphorylated SMAD2 in tumor tissue. These findings indicated that BUB1 functions as a kinase in the TGF-β pathway in a role beyond its established function in cell cycle regulation and chromosome cohesion. Copyright © 2015, American Association for the Advancement of Science.

Single Molecule Measurements of Interaction Free Energies Between the Proteins Within Binary and Ternary SNARE Complexes

PubMed Central

Liu, W.; Montana, Vedrana; Parpura, Vladimir; Mohideen, U.

2010-01-01

We use an Atomic Force Microscope based single molecule measurements to evaluate the activation free energy in the interaction of SNARE proteins syntaxin 1A, SNAP25B and synaptobrevin 2 which regulate intracellular fusion of vesicles with target membranes. The dissociation rate of the binary syntaxin-synaptobrevin and the ternary syntaxin-SNAP25B-synaptobrevin complex was measured from the rupture force distribution as a function of the rate of applied force. The temperature dependence of the spontaneous dissociation rate was used to obtain the activation energy to the transition state of 19.8 ± 3.5 kcal/mol = 33 ± 6 kBT and 25.7 ± 3.0 kcal/mol = 43 ± 5 kBT for the binary and ternary complex, respectively. They are consistent with those measured previously for the ternary complex in lipid membranes and are of order expected for bilayer fusion and pore formation. The ΔG was 12.4–16.6 kcal/mol = 21–28 kBT and 13.8–18.0 kcal/mol = 23–30 kBT for the binary and ternary complex, respectively. The ternary complex was more stable by 1.4 kcal/mol = 2.3 kBT, consistent with the spontaneous dissociation rates. The higher adhesion energies and smaller molecular extensions measured with SNAP25B point to its possible unique and important physiological role in tethering/docking the vesicle in closer proximity to the plasma membrane and increasing the probability for fusion completion. PMID:20107522

Cyclodextrin based ternary system of modafinil: Effect of trimethyl chitosan and polyvinylpyrrolidone as complexing agents.

PubMed

Patel, Parth; Agrawal, Y K; Sarvaiya, Jayrajsinh

2016-03-01

Modafinil is an approved drug for the treatment of narcolepsy and have a strong market presence in many countries. The drug is widely consumed for off-label uses and currently listed as a restricted drug. Modafinil has very low water solubility. To enhance the aqueous solubility of modafinil by the formation of a ternary complex with Hydroxypropyl-β-cyclodextrin and two hydrophilic polymers was the main objective of the present study. Pyrrolidone (PVP K30) and a water soluble chitosan derivative, trimethyl chitosan (TMC) were studied by solution state and solid state characterization methods for their discriminatory efficiency in solubility enhancement of modafinil. Phase solubility study depicted the highest complexation efficiency (2.22) of cyclodextrin derivative in the presence of TMC compared to the same in the presence of PVP K30 (0.08) and in the absence of any polymer (0.92). FT-IR analysis of binary and ternary complex expressed comparable contribution of both polymers in formation of inclusion complex. The thermal behaviour of binary and ternary complex, involving individual polymers disclosed the influence of TMC on polymorphism of the drug. DSC study revealed efficiency of TMC to prevent conversion of metastable polymorphic form to stable polymorphic form. Ternary complex, involving TMC enhanced water solubility of the drug 1.5 times more compared to the binary complex of the drug whereas PVP K30 reduced the Solubility. Copyright © 2015 Elsevier B.V. All rights reserved.

Complexin induces a conformational change at the membrane-proximal C-terminal end of the SNARE complex

PubMed Central

Choi, Ucheor B; Zhao, Minglei; Zhang, Yunxiang; Lai, Ying; Brunger, Axel T

2016-01-01

Complexin regulates spontaneous and activates Ca2+-triggered neurotransmitter release, yet the molecular mechanisms are still unclear. Here we performed single molecule fluorescence resonance energy transfer experiments and uncovered two conformations of complexin-1 bound to the ternary SNARE complex. In the cis conformation, complexin-1 induces a conformational change at the membrane-proximal C-terminal end of the ternary SNARE complex that specifically depends on the N-terminal, accessory, and central domains of complexin-1. The complexin-1 induced conformation of the ternary SNARE complex may be related to a conformation that is juxtaposing the synaptic vesicle and plasma membranes. In the trans conformation, complexin-1 can simultaneously interact with a ternary SNARE complex via the central domain and a binary SNARE complex consisting of syntaxin-1A and SNAP-25A via the accessory domain. The cis conformation may be involved in activation of synchronous neurotransmitter release, whereas both conformations may be involved in regulating spontaneous release. DOI: http://dx.doi.org/10.7554/eLife.16886.001 PMID:27253060

Oligosaccharyltransferase directly binds to ribosome at a location near the translocon-binding site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harada, Y.; Li, H.; Li, Hua

2009-04-28

Oligosaccharyltransferase (OT) transfers high mannose-type glycans to the nascent polypeptides that are translated by the membrane-bound ribosome and translocated into the lumen of the endoplasmic reticulum through the Sec61 translocon complex. In this article, we show that purified ribosomes and OT can form a binary complex with a stoichiometry of {approx}1 to 1 in the presence of detergent. We present evidence that OT may bind to the large ribosomal subunit near the site where nascent polypeptides exit. We further show that OT and the Sec61 complex can simultaneously bind to ribosomes in vitro. Based on existing data and our findings,more » we propose that cotranslational translocation and N-glycosylation of nascent polypeptides are mediated by a ternary supramolecular complex consisting of OT, the Sec61 complex, and ribosomes.« less

Oligosaccharyltransferase directly binds to ribosome at a location near the translocon-binding site

PubMed Central

Harada, Yoichiro; Li, Hua; Li, Huilin; Lennarz, William J.

2009-01-01

Oligosaccharyltransferase (OT) transfers high mannose-type glycans to the nascent polypeptides that are translated by the membrane-bound ribosome and translocated into the lumen of the endoplasmic reticulum through the Sec61 translocon complex. In this article, we show that purified ribosomes and OT can form a binary complex with a stoichiometry of ≈1 to 1 in the presence of detergent. We present evidence that OT may bind to the large ribosomal subunit near the site where nascent polypeptides exit. We further show that OT and the Sec61 complex can simultaneously bind to ribosomes in vitro. Based on existing data and our findings, we propose that cotranslational translocation and N-glycosylation of nascent polypeptides are mediated by a ternary supramolecular complex consisting of OT, the Sec61 complex, and ribosomes. PMID:19365066

Sumoylation of the net inhibitory domain (NID) is stimulated by PIAS1 and has a negative effect on the transcriptional activity of Net.

PubMed

Wasylyk, Christine; Criqui-Filipe, Paola; Wasylyk, Bohdan

2005-01-27

Net (Elk-3, Sap-2, Erp) and the related ternary complex factors Elk-1 and Sap-1 are effectors of multiple signalling pathways at the transcriptional level and play a key role in the dynamic regulation of gene expression. Net is distinct from Elk-1 and Sap-1, in that it is a strong repressor of transcription that is converted to an activator by the Ras/Erk signalling pathway. Two autonomous repression domains of Net, the NID and the CID, mediate repression. We have previously shown that the co-repressor CtBP is implicated in repression by the CID. In this report we show that repression by the NID involves a different pathway, sumoylation by Ubc9 and PIAS1. PIAS1 interacts with the NID in the two-hybrid assay and in vitro. Ubc9 and PIAS1 stimulate sumoylation in vivo of lysine 162 in the NID. Sumoylation of lysine 162 increases repression by Net and decreases the positive activity of Net. These results increase our understanding of how one of the ternary complex factors regulates transcription, and contribute to the understanding of how different domains of a transcription factor participate in the complexity of regulation of gene expression.

Luminescence enhancement of terbium(III) perchlorate by 2,2'-dipyridyl on bis(benzylsulfinyl)methane complex and luminescence mechanism.

PubMed

Feng, Shu-Yan; Li, Wen-Xian; Guo, Feng; Cao, Xiao-Fang

2014-11-01

A novel ternary complex, Tb(2)L4 · L'·(ClO4)6 · 8H2O, has been synthesized using bis(benzylsulfinyl)methane as the first ligand L and 2,2'-dipyridyl as the second ligand L'. The ternary complex was characterized by element analysis, molar conductivity, coordination titration analysis, infrared, thermogravimetric-differential scanning calorimetric and ultraviolet spectra. The results indicated that the composition of the complex was Tb2 L4 · L'·(ClO4)6 · 8H2O (L = C(6)H(5)CH(2) SOCH(2)SOCH(2)C(6)H(5); L' = Dipy). Fourier transform infrared results revealed that the perchlorate group was bonded with the Tb(III) ion by the oxygen atom, and the coordination was bidentate. The fluorescent spectra illustrated that the complex displayed characteristic fluorescence in the solid state. After the introduction of the second ligand, 2,2-dipyridyl, the relative emission intensity and fluorescence lifetime of the ternary complex Tb(2)L(4) · L'·(ClO(4))(6) · 8H2O were enhanced compared to the binary complex TbL(2.5)(ClO4)3 · 3H2O. This indicated that the presence of both organic ligand bis(benzylsulfinyl)methane and the second ligand 2,2-dipyridyl could sensitize the fluorescence intensity of Tb(III) ion, and introduction of the 2,2-dipyridyl group resulted in an enhancement of the fluorescence of the Tb(III) ternary rare earth complex. The strongest characteristic fluorescence emission intensity of the ternary complex was 9.36 times that of the binary complex. The phosphorescence spectra and fluorescence lifetime of the complex were also measured. Copyright © 2014 John Wiley & Sons, Ltd.

Conformational Control of the Binding of the Transactivation Domain of the MLL Protein and c-Myb to the KIX Domain of CREB

PubMed Central

Korkmaz, Elif Nihal; Nussinov, Ruth; Haliloğlu, Türkan

2012-01-01

The KIX domain of CBP is a transcriptional coactivator. Concomitant binding to the activation domain of proto-oncogene protein c-Myb and the transactivation domain of the trithorax group protein mixed lineage leukemia (MLL) transcription factor lead to the biologically active ternary MLL∶KIX∶c-Myb complex which plays a role in Pol II-mediated transcription. The binding of the activation domain of MLL to KIX enhances c-Myb binding. Here we carried out molecular dynamics (MD) simulations for the MLL∶KIX∶c-Myb ternary complex, its binary components and KIX with the goal of providing a mechanistic explanation for the experimental observations. The dynamic behavior revealed that the MLL binding site is allosterically coupled to the c-Myb binding site. MLL binding redistributes the conformational ensemble of KIX, leading to higher populations of states which favor c-Myb binding. The key element in the allosteric communication pathways is the KIX loop, which acts as a control mechanism to enhance subsequent binding events. We tested this conclusion by in silico mutations of loop residues in the KIX∶MLL complex and by comparing wild type and mutant dynamics through MD simulations. The loop assumed MLL binding conformation similar to that observed in the KIX∶c-Myb state which disfavors the allosteric network. The coupling with c-Myb binding site faded, abolishing the positive cooperativity observed in the presence of MLL. Our major conclusion is that by eliciting a loop-mediated allosteric switch between the different states following the binding events, transcriptional activation can be regulated. The KIX system presents an example how nature makes use of conformational control in higher level regulation of transcriptional activity and thus cellular events. PMID:22438798

Human Lipopolysaccharide-binding Protein (LBP) and CD14 Independently Deliver Triacylated Lipoproteins to Toll-like Receptor 1 (TLR1) and TLR2 and Enhance Formation of the Ternary Signaling Complex*

PubMed Central

Ranoa, Diana Rose E.; Kelley, Stacy L.; Tapping, Richard I.

2013-01-01

Bacterial lipoproteins are the most potent microbial agonists for the Toll-like receptor 2 (TLR2) subfamily, and this pattern recognition event induces cellular activation, leading to host immune responses. Triacylated bacterial lipoproteins coordinately bind TLR1 and TLR2, resulting in a stable ternary complex that drives intracellular signaling. The sensitivity of TLR-expressing cells to lipoproteins is greatly enhanced by two lipid-binding serum proteins known as lipopolysaccharide-binding protein (LBP) and soluble CD14 (sCD14); however, the physical mechanism that underlies this increased sensitivity is not known. To address this, we measured the ability of LBP and sCD14 to drive ternary complex formation between soluble extracellular domains of TLR1 and TLR2 and a synthetic triacylated lipopeptide agonist. Importantly, addition of substoichiometric amounts of either LBP or sCD14 significantly enhanced formation of a TLR1·TLR2 lipopeptide ternary complex as measured by size exclusion chromatography. However, neither LBP nor sCD14 was physically associated with the final ternary complex. Similar results were obtained using outer surface protein A (OspA), a naturally occurring triacylated lipoprotein agonist from Borrelia burgdorferi. Activation studies revealed that either LBP or sCD14 sensitized TLR-expressing cells to nanogram levels of either the synthetic lipopeptide or OspA lipoprotein agonist. Together, our results show that either LBP or sCD14 can drive ternary complex formation and TLR activation by acting as mobile carriers of triacylated lipopeptides or lipoproteins. PMID:23430250

Cyclodextrin-water soluble polymer ternary complexes enhance the solubility and dissolution behaviour of poorly soluble drugs. Case example: itraconazole.

PubMed

Taupitz, Thomas; Dressman, Jennifer B; Buchanan, Charles M; Klein, Sandra

2013-04-01

The aim of the present series of experiments was to improve the solubility and dissolution/precipitation behaviour of a poorly soluble, weakly basic drug, using itraconazole as a case example. Binary inclusion complexes of itraconazole with two commonly used cyclodextrin derivatives and a recently introduced cyclodextrin derivative were prepared. Their solubility and dissolution behaviour was compared with that of the pure drug and the marketed formulation Sporanox®. Ternary complexes were prepared by addition of Soluplus®, a new highly water soluble polymer, during the formation of the itraconazole/cyclodextrin complex. A solid dispersion made of itraconazole and Soluplus® was also studied as a control. Solid state analysis was performed for all formulations and for pure itraconazole using powder X-ray diffraction (pX-RD) and differential scanning calorimetry (DSC). Solubility tests indicated that with all formulation approaches, the aqueous solubility of itraconazole formed with hydroxypropyl-β-cyclodextrin (HP-β-CD) or hydroxybutenyl-β-cyclodextrin (HBen-β-CD) and Soluplus® proved to be the most favourable formulation approaches. Whereas the marketed formulation and the pure drug showed very poor dissolution, both of these ternary inclusion complexes resulted in fast and extensive release of itraconazole in all test media. Using the results of the dissolution experiments, a newly developed physiologically based pharmacokinetic (PBPK) in silico model was applied to compare the in vivo behaviour of Sporanox® with the predicted performance of the most promising ternary complexes from the in vitro studies. The PBPK modelling predicted that the bioavailability of itraconazole is likely to be increased after oral administration of ternary complex formulations, especially when itraconazole is formulated as a ternary complex comprising HP-β-CD or HBen-β-CD and Soluplus®. Copyright © 2012 Elsevier B.V. All rights reserved.

Mutual influence between triel bond and cation-π interactions: an ab initio study

NASA Astrophysics Data System (ADS)

Esrafili, Mehdi D.; Mousavian, Parisasadat

2017-12-01

Using ab initio calculations, the cooperative and solvent effects on cation-π and B...N interactions are studied in some model ternary complexes, where these interactions coexist. The nature of the interactions and the mechanism of cooperativity are investigated by means of quantum theory of atoms in molecules (QTAIM), noncovalent interaction (NCI) index and natural bond orbital analysis. The results indicate that all cation-π and B...N binding distances in the ternary complexes are shorter than those of corresponding binary systems. The QTAIM analysis reveals that ternary complexes have higher electron density at their bond critical points relative to the corresponding binary complexes. In addition, according to the QTAIM analysis, the formation of cation-π interaction increases covalency of B...N bonds. The NCI analysis indicates that the cooperative effects in the ternary complexes make a shift in the location of the spike associated with each interaction, which can be regarded as an evidence for the reinforcement of both cation-π and B...N interactions in these systems. Solvent effects on the cooperativity of cation-π and B...N interactions are also investigated.

Studies on Cu(II) ternary complexes involving an aminopenicillin drug and imidazole containing ligands

NASA Astrophysics Data System (ADS)

Regupathy, Sthanumoorthy; Nair, Madhavan Sivasankaran

2010-02-01

Equilibrium studies on the ternary complex systems involving ampicillin (amp) as ligand (A) and imidazole containing ligands viz., imidazole (Him), benzimidazole (Hbim), histamine (Hist) and histidine (His) as ligands (B) at 37 °C and I = 0.15 mol dm -3 (NaClO 4) show the presence of CuABH, CuAB and CuAB 2. The proton in the CuABH species is attached to ligand A. In the ternary complexes the ligand, amp(A) binds the metal ion via amino nitrogen and carbonyl oxygen atom. The CuAB (B = Hist/His)/CuAB 2 (B = Him/Hbim) species have also been isolated and the analytical data confirmed its formation. Non-electrolytic behavior and monomeric type of chelates have been assessed from their low conductance and magnetic susceptibility values. The electronic and vibrational spectral results were interpreted to find the mode of binding of ligands to metal and geometry of the complexes. This is also supported by the g tensor values calculated from ESR spectra. The thermal behaviour of complexes were studied by TGA/DTA. The redox behavior of the complexes has been studied by cyclic voltammetry. The antimicrobial activity and CT DNA cleavage study of the complexes show higher activity for ternary complexes.

Preparation, characterization and luminescence properties of core-shell ternary terbium composites SiO2(600)@Tb(MABA-Si)•L

NASA Astrophysics Data System (ADS)

Ma, Yang-Yang; Li, Wen-Xian; Zheng, Yu-Shan; Bao, Jin-Rong; Li, Yi-Lian; Feng, Li-Na; Yang, Kui-Suo; Qiao, Yan; Wu, An-Ping

2018-03-01

Two novel core-shell structure ternary terbium composites SiO2(600)@Tb(MABA-Si)·L(L:dipy/phen) nanometre luminescence materials were prepared by ternary terbium complexes Tb(MABA-Si)·L2·(ClO4)3·2H2O shell grafted onto the surface of SiO2 microspheres. And corresponding ternary terbium complexes were synthesized using (CONH(CH2)3Si(OCH2CH3)3)2 (denoted as MABA-Si) as first ligand and L as second ligand coordinated with terbium perchlorate. The as-synthesized products were characterized by means of IR spectra, 1HNMR, element analysis, molar conductivity, SEM and TEM. It was found that the first ligand MABA-Si of terbium ternary complex hydrolysed to generate the Si-OH and the Si-OH condensate with the Si-OH on the surface of SiO2 microspheres; then ligand MABA-Si grafted onto the surface of SiO2 microspheres. The diameter of SiO2 core of SiO2(600)@Tb(MABA-Si)·L was approximately 600 nm. Interestingly, the luminescence properties demonstrate that the two core-shell structure ternary terbium composites SiO2(600)Tb(MABA-Si)·L(dipy/phen) exhibit strong emission intensities, which are 2.49 and 3.35 times higher than that of the corresponding complexes Tb(MABA-Si)·L2·(ClO4)3·2H2O, respectively. Luminescence decay curves show that core-shell structure ternary terbium composites have longer lifetime. Excellent luminescence properties enable the core-shell materials to have potential applications in medicine, industry, luminescent fibres and various biomaterials fields.

Preparation, characterization and luminescence properties of core-shell ternary terbium composites SiO2(600)@Tb(MABA-Si)•L.

PubMed

Ma, Yang-Yang; Li, Wen-Xian; Zheng, Yu-Shan; Bao, Jin-Rong; Li, Yi-Lian; Feng, Li-Na; Yang, Kui-Suo; Qiao, Yan; Wu, An-Ping

2018-03-01

Two novel core-shell structure ternary terbium composites SiO 2(600) @Tb(MABA-Si)·L(L:dipy/phen) nanometre luminescence materials were prepared by ternary terbium complexes Tb(MABA-Si)·L 2 ·(ClO 4 ) 3 ·2H 2 O shell grafted onto the surface of SiO 2 microspheres. And corresponding ternary terbium complexes were synthesized using (CONH(CH 2 ) 3 Si(OCH 2 CH 3 ) 3 ) 2 (denoted as MABA-Si) as first ligand and L as second ligand coordinated with terbium perchlorate. The as-synthesized products were characterized by means of IR spectra, 1 HNMR, element analysis, molar conductivity, SEM and TEM. It was found that the first ligand MABA-Si of terbium ternary complex hydrolysed to generate the Si-OH and the Si-OH condensate with the Si-OH on the surface of SiO 2 microspheres; then ligand MABA-Si grafted onto the surface of SiO 2 microspheres. The diameter of SiO 2 core of SiO 2(600) @Tb(MABA-Si)·L was approximately 600 nm. Interestingly, the luminescence properties demonstrate that the two core-shell structure ternary terbium composites SiO 2(600) Tb(MABA-Si)·L(dipy/phen) exhibit strong emission intensities, which are 2.49 and 3.35 times higher than that of the corresponding complexes Tb(MABA-Si)·L 2 ·(ClO 4 ) 3 ·2H 2 O, respectively. Luminescence decay curves show that core-shell structure ternary terbium composites have longer lifetime. Excellent luminescence properties enable the core-shell materials to have potential applications in medicine, industry, luminescent fibres and various biomaterials fields.

Preparation, characterization and luminescence properties of core–shell ternary terbium composites SiO2(600)@Tb(MABA-Si)•L

PubMed Central

Ma, Yang-Yang; Zheng, Yu-Shan; Bao, Jin-Rong; Li, Yi-Lian; Feng, Li-Na; Yang, Kui-Suo; Qiao, Yan; Wu, An-Ping

2018-01-01

Two novel core–shell structure ternary terbium composites SiO2(600)@Tb(MABA-Si)·L(L:dipy/phen) nanometre luminescence materials were prepared by ternary terbium complexes Tb(MABA-Si)·L2·(ClO4)3·2H2O shell grafted onto the surface of SiO2 microspheres. And corresponding ternary terbium complexes were synthesized using (CONH(CH2)3Si(OCH2CH3)3)2 (denoted as MABA-Si) as first ligand and L as second ligand coordinated with terbium perchlorate. The as-synthesized products were characterized by means of IR spectra, 1HNMR, element analysis, molar conductivity, SEM and TEM. It was found that the first ligand MABA-Si of terbium ternary complex hydrolysed to generate the Si–OH and the Si–OH condensate with the Si–OH on the surface of SiO2 microspheres; then ligand MABA-Si grafted onto the surface of SiO2 microspheres. The diameter of SiO2 core of SiO2(600)@Tb(MABA-Si)·L was approximately 600 nm. Interestingly, the luminescence properties demonstrate that the two core–shell structure ternary terbium composites SiO2(600)Tb(MABA-Si)·L(dipy/phen) exhibit strong emission intensities, which are 2.49 and 3.35 times higher than that of the corresponding complexes Tb(MABA-Si)·L2·(ClO4)3·2H2O, respectively. Luminescence decay curves show that core–shell structure ternary terbium composites have longer lifetime. Excellent luminescence properties enable the core–shell materials to have potential applications in medicine, industry, luminescent fibres and various biomaterials fields. PMID:29657773

Remarkable high efficiency of red emitters using Eu(iii) ternary complexes.

PubMed

Kalyakina, Alena S; Utochnikova, Valentina V; Zimmer, Manuel; Dietrich, Fabian; Kaczmarek, Anna M; Van Deun, Rik; Vashchenko, Andrey A; Goloveshkin, Alexander S; Nieger, Martin; Gerhards, Markus; Schepers, Ute; Bräse, Stefan

2018-05-17

We have synthesized Eu(iii) ternary complexes possessing record photoluminescence yields up to 90%. This high luminescence performance resulted from the absence of quenching moieties in the Eu coordination environment and an efficient energy transfer between ligands, combined with a particular symmetry of the coordination environment.

Thermodynamic Investigation and Mixed Ligand Complex Formation of 1,4-Bis-(3-aminopropyl)-piperazine and Biorelevant Ligands.

PubMed

El-Sherif, Ahmed A; Shehata, Mohamed R; Shoukry, Mohamed M; Barakat, Mohammad H

2012-01-01

Thermodynamic parameters for protonation of 1,4-bis(3-aminopropyl)-piperazine (BAPP) and its metal complexation with some divalent metal ions were determined in aqueous solution at constant ionic strength (0.1 M NaNO(3)) using a potentiometric technique. The order of -ΔG(0) and -ΔH(0) was found to obey Co(2+) < Ni(2+) < Cu(2+) > Zn(2+), in accordance with the Irving-Williams order. The formation equilibria of zinc (II) complexes and the ternary complexes Zn(BAPP)L, where L = amino acid, amides, or DNA constituents), have been investigated. Ternary complexes are formed by a simultaneous mechanism. The concentration distribution of the complexes in solution was evaluated as a function of pH. Stoichiometry and stability constants for the complexes formed are reported and discussed. The stability of ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameter Δlog K.

Thermodynamic Investigation and Mixed Ligand Complex Formation of 1,4-Bis-(3-aminopropyl)-piperazine and Biorelevant Ligands

PubMed Central

El-Sherif, Ahmed A.; Shehata, Mohamed R.; Shoukry, Mohamed M.; Barakat, Mohammad H.

2012-01-01

Thermodynamic parameters for protonation of 1,4-bis(3-aminopropyl)-piperazine (BAPP) and its metal complexation with some divalent metal ions were determined in aqueous solution at constant ionic strength (0.1 M NaNO3) using a potentiometric technique. The order of –ΔG0 and –ΔH0 was found to obey Co2+ < Ni2+ < Cu2+ > Zn2+, in accordance with the Irving-Williams order. The formation equilibria of zinc (II) complexes and the ternary complexes Zn(BAPP)L, where L = amino acid, amides, or DNA constituents), have been investigated. Ternary complexes are formed by a simultaneous mechanism. The concentration distribution of the complexes in solution was evaluated as a function of pH. Stoichiometry and stability constants for the complexes formed are reported and discussed. The stability of ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameter Δlog K. PMID:23226992

Reconstitution of R-spondin:LGR4:ZNRF3 adult stem cell growth factor signaling complexes with recombinant proteins produced in Escherichia coli.

PubMed

Moad, Heather E; Pioszak, Augen A

2013-10-15

R-Spondins are secreted glycoproteins (RSPO1-RSPO4) that have proliferative effects on adult stem cells by potentiating Wnt signaling. RSPO actions are mediated by the leucine-rich repeat (LRR)-containing seven-transmembrane receptors LGR4-LGR6 and the transmembrane E3 ubiquitin ligases ZNRF3 and RNF43. Here, we present a methodology for the bacterial expression and purification of the signaling competent, cysteine-rich Fu1-Fu2 domains of the four human RSPOs, a fragment of the human LGR4 extracellular domain (ECD) containing LRR1-14, and the human ZNRF3 ECD. In a cell-based signaling assay, the nonglycosylated RSPOs enhanced low-dose Wnt3a signaling with potencies comparable to those of mammalian cell-produced RSPOs and RSPO2 and -3 were more potent than RSPO1 and -4. LGR4 LRR1-14 and ZNRF3 ECD inhibited RSPO2-enhanced Wnt3a signaling. The RSPOs bound LGR4 LRR1-14 with nanomolar affinities that decreased in the following order in a time-resolved fluorescence resonance energy transfer (TR-FRET) assay: RSPO4 > RSPO2 > RSPO3 > RSPO1. RSPO-receptor interactions were further characterized with a native gel electrophoretic mobility shift assay, which corroborated the RSPO-LGR4 TR-FRET results and indicated that RSPOs weakly bound ZNRF3 with affinities that decreased in the following order: RSPO2 > RSPO3 > RSPO1. RSPO4:ZNRF3 complexes were not detected. Lastly, ternary RSPO:LGR4:ZNRF3 complexes were detected for RSPO2 and -3. Our results indicate that RSPO and LGR4 N-glycans are dispensable for function, demonstrate RSPO-mediated ternary complex formation, and suggest that the stronger signaling potencies of RSPO2 and -3 result from their strong binding of both receptors. Our unique protein production methodology may provide a cost-effective source of recombinant RSPOs for regenerative medicine applications.

Ternary borate-nucleoside complex stabilization by Ribonuclease A demonstrates phosphate mimicry

PubMed Central

Gabel, Scott A.; London, Robert E.

2010-01-01

Phosphate esters play a central role in cellular energetics, biochemical activation, signal transduction and conformational switching. The structural homology of the borate anion with phosphate, combined with its ability to spontaneously esterify hydroxyl groups, suggested that phosphate-ester recognition sites on proteins might exhibit significant affinity for non-enzymatically formed borate esters. 11B NMR studies and activity measurements on ribonuclease A in the presence of borate and several cytidine analogs demonstrate the formation of a stable ternary RNase A•3′-deoxycytidine-2′-borate ternary complex that mimics the complex formed between RNase A and a 2′-cytidine monophosphate (2′-CMP) inhibitor. Alternatively, no slowly exchanging borate resonance is observed for a ternary RNase A, borate, 2′-deoxycytidine mixture, demonstrating the critical importance of the 2′-hydroxyl group for complex formation. Titration of the ternary complex with 2′-CMP shows that it can displace the bound borate ester with a binding constant that is close to the reported inhibition constant of RNase A by 2′CMP. RNase A binding of a cyclic cytidine-2′,3′-borate ester, which is a structural homolog of the cytidine-2′,3′-cyclic phosphate substrate, could also be demonstrated. The apparent dissociation constant for the cytidine-2′,3′-borate•RNase A complex is 0.8 mM, which compares with a Michaelis constant of 11 mM for cCMP at pH 7, indicating considerably stronger binding. However, the value is 1000-fold larger than the reported dissociation constant of the RNase A complex with uridine-vanadate. These results are consistent with recent reports suggesting that in situ formation of borate esters that mimic the corresponding phosphate esters support enzyme catalysis. PMID:17957392

Structural characterization of a new lipid/DNA complex showing a selective transfection efficiency in ovarian cancer cells

NASA Astrophysics Data System (ADS)

Caracciolo, G.; Pozzi, D.; Caminiti, R.; Congiu Castellano, A.

2003-04-01

We investigated, for the first time, by using Energy Dispersive X-ray Diffraction, the structure of a new ternary cationic liposome formulated with dioleoyl trimethylammonium propane (DOTAP), 1,2-dioleoyl-3-phosphatidylethanolamine (DOPE) and cholesterol (Chol) (DDC) which has been recently found to have a selective high gene transfer ability in ovarian cancer cells. Our structural results provide a further experimental support to the widely accepted statement that there is not a simple and direct correlation between structure and transfection efficiency and that the factors controlling cationic lipid/DNA (CL-DNA) complexes-mediated gene transfer depend not only on the formulations of the cationic liposomes and their thermodynamic phase, but also significantly on the cell properties.

Allostery Mediates Ligand Binding to Grb2 Adaptor in a Mutually Exclusive Manner

PubMed Central

McDonald, Caleb B.; El Hokayem, Jimmy; Zafar, Nawal; Balke, Jordan E.; Bhat, Vikas; Mikles, David C.; Deegan, Brian J.; Seldeen, Kenneth L.; Farooq, Amjad

2012-01-01

Allostery plays a key role in dictating the stoichiometry and thermodynamics of multi-protein complexes driving a plethora of cellular processes central to health and disease. Herein, using various biophysical tools, we demonstrate that although Sos1 nucleotide exchange factor and Gab1 docking protein recognize two non-overlapping sites within the Grb2 adaptor, allostery promotes the formation of two distinct pools of Grb2-Sos1 and Grb2-Gab1 binary signaling complexes in concert in lieu of a composite Sos1-Grb2-Gab1 ternary complex. Of particular interest is the observation that the binding of Sos1 to the nSH3 domain within Grb2 sterically blocks the binding of Gab1 to the cSH3 domain and vice versa in a mutually exclusive manner. Importantly, the formation of both the Grb2-Sos1 and Grb2-Gab1 binary complexes is governed by a stoichiometry of 2:1, whereby the respective SH3 domains within Grb2 homodimer bind to Sos1 and Gab1 via multivalent interactions. Collectively, our study sheds new light on the role of allostery in mediating cellular signaling machinery. PMID:23334917

Formulation of ternary complexes of glyburide with hydroxypropyl-β-cyclodextrin and other solubilizing agents and their effect on release behavior of glyburide in aqueous and buffered media at different agitation speeds.

PubMed

Singh, Sachin Kumar; Srinivasan, K K; Singare, Dhananjay S; Gowthamarajan, K; Prakash, Dev

2012-11-01

Glyburide, a sulfonylurea derivative, widely used as hypoglycaemic agent. In the present study, an attempt has been made to investigate the most effective third component which can be used with hydroxylpropyl-β-cyclodextrin (HPβCd) to form a ternary complex with glyburide in order to enhance its dissolution rate, as well as reduce the amount of HPβCd used for formulating the binary complex with glyburide. Moreover, the objective of this study was also to develop a discriminatory dissolution media in order to discriminate the effect of the different solubilizing agents used for formulating the ternary complex system. Sodium lauryl sulphate, Poloxamer-188, Polyvinylpyrrolidone K-30, lactose and L-arginine were used to formulate ternary system along with HPβCd and glyburide. The ternary system formulated with glyburide:HPβCd:L-arginine in a proportion of 1:1:0.5 has shown the fastest dissolution rate when compared to other solubilizing agents. Unbuffered aqueous media with stirring speed 50 rpm has produced the most discriminatory dissolution profiles. The DSC thermograms and the powder X-ray analysis revealed the decrease in crystallinity of the drug. This was an indication of amorphous solid dispersion or molecular encapsulation of the drug into the cyclodextrin cavity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xia, Shuangluo; Vashishtha, Ashwani; Bulkley, David

During DNA synthesis, base stacking and Watson-Crick (WC) hydrogen bonding increase the stability of nascent base pairs when they are in a ternary complex. To evaluate the contribution of base stacking to the incorporation efficiency of dNTPs when a DNA polymerase encounters an abasic site, we varied the penultimate base pairs (PBs) adjacent to the abasic site using all 16 possible combinations. We then determined pre-steady-state kinetic parameters with an RB69 DNA polymerase variant and solved nine structures of the corresponding ternary complexes. The efficiency of incorporation for incoming dNTPs opposite an abasic site varied between 2- and 210-fold dependingmore » on the identity of the PB. We propose that the A rule can be extended to encompass the fact that DNA polymerase can bypass dA/abasic sites more efficiently than other dN/abasic sites. Crystal structures of the ternary complexes show that the surface of the incoming base was stacked against the PB's interface and that the kinetic parameters for dNMP incorporation were consistent with specific features of base stacking, such as surface area and partial charge-charge interactions between the incoming base and the PB. Without a templating nucleotide residue, an incoming dNTP has no base with which it can hydrogen bond and cannot be desolvated, so that these surrounding water molecules become ordered and remain on the PB's surface in the ternary complex. When these water molecules are on top of a hydrophobic patch on the PB, they destabilize the ternary complex, and the incorporation efficiency of incoming dNTPs is reduced.« less

Crystallization and preliminary X-ray analysis of binary and ternary complexes of Haloferax mediterranei glucose dehydrogenase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esclapez, Julia; Britton, K. Linda; Baker, Patrick J.

2005-08-01

Single crystals of binary and ternary complexes of wild-type and D38C mutant H. mediterranei glucose dehydrogenase have been obtained by the hanging-drop vapour-diffusion method. Haloferax mediterranei glucose dehydrogenase (EC 1.1.1.47) belongs to the medium-chain alcohol dehydrogenase superfamily and requires zinc for catalysis. In the majority of these family members, the catalytic zinc is tetrahedrally coordinated by the side chains of a cysteine, a histidine, a cysteine or glutamate and a water molecule. In H. mediterranei glucose dehydrogenase, sequence analysis indicates that the zinc coordination is different, with the invariant cysteine replaced by an aspartate residue. In order to analyse themore » significance of this replacement and to contribute to an understanding of the role of the metal ion in catalysis, a range of binary and ternary complexes of the wild-type and a D38C mutant protein have been crystallized. For most of the complexes, crystals belonging to space group I222 were obtained using sodium/potassium citrate as a precipitant. However, for the binary and non-productive ternary complexes with NADPH/Zn, it was necessary to replace the citrate with 2-methyl-2,4-pentanediol. Despite the radical change in conditions, the crystals thus formed were isomorphous.« less

Destabilization of strigolactone receptor DWARF14 by binding of ligand and E3-ligase signaling effector DWARF3

PubMed Central

Zhao, Li-Hua; Zhou, X Edward; Yi, Wei; Wu, Zhongshan; Liu, Yue; Kang, Yanyong; Hou, Li; de Waal, Parker W; Li, Suling; Jiang, Yi; Scaffidi, Adrian; Flematti, Gavin R; Smith, Steven M; Lam, Vinh Q; Griffin, Patrick R; Wang, Yonghong; Li, Jiayang; Melcher, Karsten; Xu, H Eric

2015-01-01

Strigolactones (SLs) are endogenous hormones and exuded signaling molecules in plant responses to low levels of mineral nutrients. Key mediators of the SL signaling pathway in rice include the α/β-fold hydrolase DWARF 14 (D14) and the F-box component DWARF 3 (D3) of the ubiquitin ligase SCFD3 that mediate ligand-dependent degradation of downstream signaling repressors. One perplexing feature is that D14 not only functions as the SL receptor but is also an active enzyme that slowly hydrolyzes diverse natural and synthetic SLs including GR24, preventing the crystallization of a binary complex of D14 with an intact SL as well as the ternary D14/SL/D3 complex. Here we overcome these barriers to derive a structural model of D14 bound to intact GR24 and identify the interface that is required for GR24-mediated D14-D3 interaction. The mode of GR24-mediated signaling, including ligand recognition, hydrolysis by D14, and ligand-mediated D14-D3 interaction, is conserved in structurally diverse SLs. More importantly, D14 is destabilized upon the binding of ligands and D3, thus revealing an unusual mechanism of SL recognition and signaling, in which the hormone, the receptor, and the downstream effectors are systematically destabilized during the signal transduction process. PMID:26470846

On the binding of indeno[1,2-c]isoquinolines in the DNA-topoisomerase I cleavage complex.

PubMed

Xiao, Xiangshu; Antony, Smitha; Pommier, Yves; Cushman, Mark

2005-05-05

An ab initio quantum mechanics calculation is reported which predicts the orientation of indenoisoquinoline 4 in the ternary cleavage complex formed from DNA and topoisomerase I (top1). The results of this calculation are consistent with the hypothetical structures previously proposed for the indenoisoquinoline-DNA-top1 ternary complexes based on molecular modeling, the crystal structure of a recently reported ternary complex, and the biological results obtained with a pair of diaminoalkyl-substituted indenoisoquinoline enantiomers. The results of these studies indicate that the pi-pi stacking interactions between the indenoisoquinolines and the neighboring DNA base pairs play a major role in determining binding orientation. The calculation of the electrostatic potential surface maps of the indenoisoquinolines and the adjacent DNA base pairs shows electrostatic complementarity in the observed binding orientation, leading to the conclusion that electrostatic attraction between the intercalators and the base pairs in the cleavage complex plays a major stabilizing role. On the other hand, the calculation of LUMO and HOMO energies of indenoisoquinoline 13b and neighboring DNA base pairs in conjunction with NBO analysis indicates that charge transfer complex formation plays a relatively minor role in stabilizing the ternary complexes derived from indenoisoquinolines, DNA, and top1. The results of these studies are important in understanding the existing structure-activity relationships for the indenoisoquinolines as top1 inhibitors and as anticancer agents, and they will be important in the future design of indenoisoquinoline-based top1 inhibitors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yazhen; Musser, Sarah K.; Saleh, Sam

1,N{sup 2}-Propanodeoxyguanosine (PdG) is a stable structural analogue for the 3-(2'-deoxy-{beta}-d-erythro-pentofuranosyl)pyrimido[1,2-?]purin-10(3H)-one (M{sub 1}dG) adduct derived from exposure of DNA to base propenals and to malondialdehyde. The structures of ternary polymerase-DNA-dNTP complexes for three template-primer DNA sequences were determined, with the Y-family Sulfolobus solfataricus DNA polymerase IV (Dpo4), at resolutions between 2.4 and 2.7 {angstrom}. Three template 18-mer-primer 13-mer sequences, 5'-d(TCACXAAATCCTTCCCCC)-3'{center_dot}5'-d(GGGGGAAGGATTT)-3' (template I), 5'-d(TCACXGAATCCTTCCCCC)-3'{center_dot}5'-d(GGGGGAAGGATTC)-3' (template II), and 5'-d(TCATXGAATCCTTCCCCC)-3'{center_dot}5'-d(GGGGGAAGGATTC)-3' (template III), where X is PdG, were analyzed. With templates I and II, diffracting ternary complexes including dGTP were obtained. The dGTP did not pair with PdG, but instead with the 5'-neighboring templatemore » dC, utilizing Watson-Crick geometry. Replication bypass experiments with the template-primer 5?-TCACXAAATCCTTACGAGCATCGCCCCC-3'{center_dot}5'-GGGGGCGATGCTCGTAAGGATTT-3', where X is PdG, which includes PdG in the 5'-CXA-3' template sequence as in template I, showed that the Dpo4 polymerase inserted dGTP and dATP when challenged by the PdG adduct. For template III, in which the template sequence was 5'-TXG-3', a diffracting ternary complex including dATP was obtained. The dATP did not pair with PdG, but instead with the 5'-neighboring T, utilizing Watson-Crick geometry. Thus, all three ternary complexes were of the 'type II' structure described for ternary complexes with native DNA [Ling, H., Boudsocq, F., Woodgate, R., and Yang, W. (2001) Cell 107, 91--102]. The PdG adduct remained in the anti conformation about the glycosyl bond in each of these threee ternary complexes. These results provide insight into how -1 frameshift mutations might be generated for the PdG adduct, a structural model for the exocylic M{sub 1}dG adduct formed by malondialdehyde.« less

Xanthomonas TAL effectors hijack host basal transcription factor IIA α and γ subunits for invasion.

PubMed

Ma, Ling; Wang, Qiang; Yuan, Meng; Zou, Tingting; Yin, Ping; Wang, Shiping

2018-02-05

The Xanthomonas genus includes Gram-negative plant-pathogenic bacteria, which infect a broad range of crops and wild plant species, cause symptoms with leaf blights, streaks, spots, stripes, necrosis, wilt, cankers and gummosis on leaves, stems and fruits in a wide variety of plants via injecting their effector proteins into the host cell during infection. Among these virulent effectors, transcription activator-like effectors (TALEs) interact with the γ subunit of host transcription factor IIA (TFIIAγ) to activate the transcription of host disease susceptibility genes. Functional TFIIA is a ternary complex comprising α, β and γ subunits. However, whether TALEs recruit TFIIAα, TFIIAβ, or both remains unknown. The underlying molecular mechanisms by which TALEs mediate host susceptibility gene activation require full elucidation. Here, we show that TALEs interact with the α+γ binary subcomplex but not the α+β+γ ternary complex of rice TFIIA (holo-OsTFIIA). The transcription factor binding (TFB) regions of TALEs, which are highly conserved in Xanthomonas species, have a dominant role in these interactions. Furthermore, the interaction between TALEs and the α+γ complex exhibits robust DNA binding activity in vitro. These results collectively demonstrate that TALE-carrying pathogens hijack the host basal transcription factors TFIIAα and TFIIAγ, but not TFIIAβ, to enhance host susceptibility during pathogen infection. The uncovered mechanism widens new insights on host-microbe interaction and provide an applicable strategy to breed high-resistance crop varieties. Copyright © 2018 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cody, Vivian, E-mail: cody@hwi.buffalo.edu; University of Buffalo, Buffalo, NY 14260; Pace, Jim

The structures of mouse DHFR holo enzyme and a ternary complex with NADPH and a potent inhibitor are described. It has been shown that 2, 4-diamino-6-arylmethylpteridines and 2, 4-diamino-5-arylmethylpyrimidines containing an O-carboxylalkyloxy group in the aryl moiety are potent and selective inhibitors of the dihydrofolate reductase (DHFR) from opportunistic pathogens such as Pneumocystis carinii, the causative agent of Pneumocystis pneumonia in HIV/AIDS patients. In order to understand the structure–activity profile observed for a series of substituted dibenz[b, f]azepine antifolates, the crystal structures of mouse DHFR (mDHFR; a mammalian homologue) holo and ternary complexes with NADPH and the inhibitor 2, 4-diamino-6-(2′-hydroxydibenz[b,more » f]azepin-5-yl)methylpteridine were determined to 1.9 and 1.4 Å resolution, respectively. Structural data for the ternary complex with the potent O-(3-carboxypropyl) inhibitor PT684 revealed no electron density for the O-carboxylalkyloxy side chain. The side chain was either cleaved or completely disordered. The electron density fitted the less potent hydroxyl compound PT684a. Additionally, cocrystallization of mDHFR with NADPH and the less potent 2′-(4-carboxybenzyl) inhibitor PT682 showed no electron density for the inhibitor and resulted in the first report of a holoenzyme complex despite several attempts at crystallization of a ternary complex. Modeling data of PT682 in the active site of mDHFR and P. carinii DHFR (pcDHFR) indicate that binding would require ligand-induced conformational changes to the enzyme for the inhibitor to fit into the active site or that the inhibitor side chain would have to adopt an alternative binding mode to that observed for other carboxyalkyloxy inhibitors. These data also show that the mDHFR complexes have a decreased active-site volume as reflected in the relative shift of helix C (residues 59–64) by 0.6 Å compared with pcDHFR ternary complexes. These data are consistent with the greater inhibitory potency against pcDHFR.« less

The equilibrium constant of complex formation in solution: A study utilizing a dielectric constant method

NASA Astrophysics Data System (ADS)

Loh, C. W.

1980-03-01

A method was developed for determining equilibrium constants, heat of reaction, and change in free energy and entropy during a 1:1 complex formation in solutions. The measurements were carried out on ternary systems containing two interacting solutes in an inert solvent. The procedures was applied to the investigation of hydrogen bond complex formations in two mixtures systems, phenol and pyridine in carbon tetrachloride, and 4, 5, 6, 7-tetrachloro-2-trifluoromethylbenzimidazole (TTFB) and alkyl acetate in styrene. The first mixture system was studied in order to compare the results with those obtained by other methods. Results for the second mixture system indicated strong association between molecules of TTFB and alkyl acetate and suggested that the blocking of valinomycin-mediated bilayer membrane conductance by substituted benzimidazoles was due to competition for a limited number of adsorption sites on the membrane surface.

Siderocalin-mediated recognition, sensitization, and cellular uptake of actinides.

PubMed

Allred, Benjamin E; Rupert, Peter B; Gauny, Stacey S; An, Dahlia D; Ralston, Corie Y; Sturzbecher-Hoehne, Manuel; Strong, Roland K; Abergel, Rebecca J

2015-08-18

Synthetic radionuclides, such as the transuranic actinides plutonium, americium, and curium, present severe health threats as contaminants, and understanding the scope of the biochemical interactions involved in actinide transport is instrumental in managing human contamination. Here we show that siderocalin, a mammalian siderophore-binding protein from the lipocalin family, specifically binds lanthanide and actinide complexes through molecular recognition of the ligands chelating the metal ions. Using crystallography, we structurally characterized the resulting siderocalin-transuranic actinide complexes, providing unprecedented insights into the biological coordination of heavy radioelements. In controlled in vitro assays, we found that intracellular plutonium uptake can occur through siderocalin-mediated endocytosis. We also demonstrated that siderocalin can act as a synergistic antenna to sensitize the luminescence of trivalent lanthanide and actinide ions in ternary protein-ligand complexes, dramatically increasing the brightness and efficiency of intramolecular energy transfer processes that give rise to metal luminescence. Our results identify siderocalin as a potential player in the biological trafficking of f elements, but through a secondary ligand-based metal sequestration mechanism. Beyond elucidating contamination pathways, this work is a starting point for the design of two-stage biomimetic platforms for photoluminescence, separation, and transport applications.

Siderocalin-mediated recognition, sensitization, and cellular uptake of actinides

PubMed Central

Allred, Benjamin E.; Rupert, Peter B.; Gauny, Stacey S.; An, Dahlia D.; Ralston, Corie Y.; Sturzbecher-Hoehne, Manuel; Strong, Roland K.; Abergel, Rebecca J.

2015-01-01

Synthetic radionuclides, such as the transuranic actinides plutonium, americium, and curium, present severe health threats as contaminants, and understanding the scope of the biochemical interactions involved in actinide transport is instrumental in managing human contamination. Here we show that siderocalin, a mammalian siderophore-binding protein from the lipocalin family, specifically binds lanthanide and actinide complexes through molecular recognition of the ligands chelating the metal ions. Using crystallography, we structurally characterized the resulting siderocalin–transuranic actinide complexes, providing unprecedented insights into the biological coordination of heavy radioelements. In controlled in vitro assays, we found that intracellular plutonium uptake can occur through siderocalin-mediated endocytosis. We also demonstrated that siderocalin can act as a synergistic antenna to sensitize the luminescence of trivalent lanthanide and actinide ions in ternary protein–ligand complexes, dramatically increasing the brightness and efficiency of intramolecular energy transfer processes that give rise to metal luminescence. Our results identify siderocalin as a potential player in the biological trafficking of f elements, but through a secondary ligand-based metal sequestration mechanism. Beyond elucidating contamination pathways, this work is a starting point for the design of two-stage biomimetic platforms for photoluminescence, separation, and transport applications. PMID:26240330

An in vitro study of interactions between insulin-mimetic zinc(II) complexes and selected plasma components.

PubMed

Enyedy, Eva Anna; Horváth, László; Gajda-Schrantz, Krisztina; Galbács, Gábor; Kiss, Tamás

2006-12-01

The speciations of some potent insulin-mimetic zinc(II) complexes of bidentate ligands: maltol and 1,2-dimethyl-3-hydroxypyridinone with (O,O) and picolinic acid with (N,O) coordination modes, were studied via solution equilibrium investigations of the ternary complex formation in the presence of small relevant bioligands of the blood serum such as cysteine, histidine and citric acid. Results show that formation of the ternary complexes, especially with cysteine, is favoured at physiological pH range in almost all systems studied. Besides these low molecular mass binders, serum proteins among others albumin and transferrin can bind zinc(II) or its complexes. Accordingly, the distribution of zinc(II) between the small and high molecular mass fractions of the serum was also studied by ultrafiltration. Modelling calculations relating to the distribution of zinc(II), using the stability constants of the ternary complexes studied and those of the serum proteins reported in the literature, confirmed the ultrafiltration results, namely, the primary role of albumin in zinc(II) binding among the low and high molecular mass components of the serum.

An inhibitor of eIF2 activity in the sRNA pool of eukaryotic cells.

PubMed

Centrella, Michael; Porter, David L; McCarthy, Thomas L

2011-08-15

Eukaryotic protein synthesis is a multi-step and highly controlled process that includes an early initiation complex containing eukaryotic initiation factor 2 (eIF2), GTP, and methionine-charged initiator methionyl-tRNA (met-tRNAi). During studies to reconstruct formation of the ternary complex containing these molecules, we detected a potent inhibitor in low molecular mass RNA (sRNA) preparations of eukaryotic tRNA. The ternary complex inhibitor (TCI) was retained in the total sRNA pool after met-tRNAi was charged by aminoacyl tRNA synthetase, co-eluted with sRNA by size exclusion chromatography, but resolved from met-tRNAi by ion exchange chromatography. The adverse effect of TCI was not overcome by high GTP or magnesium omission and was independent of GTP regeneration. Rather, TCI suppressed the rate of ternary complex formation, and disrupted protein synthesis and the accumulation of heavy polymeric ribosomes in reticulocyte lysates in vitro. Lastly, a component or components in ribosome depleted cell lysate significantly reversed TCI activity. Since assembly of the met-tRNAi/eIF2/GTP ternary complex is integral to protein synthesis, awareness of TCI is important to avoid confusion in studies of translation initiation. A clear definition of TCI may also allow a better appreciation of physiologic or pathologic situations, factors, and events that control protein synthesis in vivo. Copyright © 2011 Elsevier B.V. All rights reserved.

Inositol hexakisphosphate kinase-1 mediates assembly/disassembly of the CRL4–signalosome complex to regulate DNA repair and cell death

PubMed Central

Rao, Feng; Xu, Jing; Khan, A. Basit; Gadalla, Moataz M.; Cha, Jiyoung Y.; Xu, Risheng; Tyagi, Richa; Dang, Yongjun; Chakraborty, Anutosh; Snyder, Solomon H.

2014-01-01

Inositol polyphosphates containing an energetic pyrophosphate bond are formed primarily by a family of three inositol hexakisphosphate (IP6) kinases (IP6K1–3). The Cullin-RING ubiquitin ligases (CRLs) regulate diverse biological processes through substrate ubiquitylation. CRL4, comprising the scaffold Cullin 4A/B, the E2-interacting Roc1/2, and the adaptor protein damage-specific DNA-binding protein 1, is activated by DNA damage. Basal CRL4 activity is inhibited by binding to the COP9 signalosome (CSN). UV radiation and other stressors dissociate the complex, leading to E3 ligase activation, but signaling events that trigger signalosome dissociation from CRL4 have been unclear. In the present study, we show that, under basal conditions, IP6K1 forms a ternary complex with CSN and CRL4 in which IP6K1 and CRL4 are inactive. UV dissociates IP6K1 to generate IP7, which then dissociates CSN–CRL4 to activate CRL4. Thus, IP6K1 is a novel CRL4 subunit that transduces UV signals to mediate disassembly of the CRL4–CSN complex, thereby regulating nucleotide excision repair and cell death. PMID:25349427

Improved Aqueous Solubility and Antihypercholesterolemic Activity of Ezetimibe on Formulating with Hydroxypropyl-β-Cyclodextrin and Hydrophilic Auxiliary Substances.

PubMed

Srivalli, Kale Mohana Raghava; Mishra, Brahmeshwar

2016-04-01

The purpose of this study was to improve the aqueous solubility, dissolution, and pharmacodynamic properties of a BCS class II drug, ezetimibe (Eze) by preparing ternary cyclodextrin complex systems. We investigated the potential synergistic effect of two novel hydrophilic auxiliary substances, D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) and L-ascorbic acid-2-glucoside (AA2G) on hydroxypropyl-β-cyclodextrin (HPBCD) solubilization of poorly water-soluble hypocholesterolemic drug, Eze. In solution state, the binary and ternary systems were analyzed by phase solubility studies and Job's plot. The solid complexes prepared by freeze-drying were characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and scanning electron microscopy (SEM). The log P values, aqueous solubility, dissolution, and antihypercholesterolemic activity of all systems were studied. The analytical techniques confirmed the formation of inclusion complexes in the binary and ternary systems. HPBCD complexation significantly (p < 0.05) reduced the log P and improved the solubility, dissolution, and hypocholesterolemic properties of Eze, and the addition of ternary component produced further significant improvement (p < 0.05) even compared to binary system. The remarkable reduction in log P and enhancement in solubility, dissolution, and antihypercholesterolemic activity due to the addition of TPGS or AA2G may be attributed to enhanced wetting, dispersibility, and complete amorphization. The use of TPGS or AA2G as ternary hydrophilic auxiliary substances improved the HPBCD solubilization and antihypercholesterolemic activity of Eze.

Ternary copper(II) complexes with amino acid chains and heterocyclic bases: DNA binding, cytotoxic and cell apoptosis induction properties.

PubMed

Ma, Tieliang; Xu, Jun; Wang, Yuan; Yu, Hao; Yang, Yong; Liu, Yang; Ding, Weiliang; Zhu, Wenjiao; Chen, Ruhua; Ge, Zhijun; Tan, Yongfei; Jia, Lei; Zhu, Taofeng

2015-03-01

Nowadays, chemotherapy is a common means of oncology. However, it is difficult to find excellent chemotherapy drugs. Here we reported three new ternary copper(II) complexes which have potential chemotherapy characteristics with reduced Schiff base ligand and heterocyclic bases (TBHP), [Cu(phen)(TBHP)]H2O (1), [Cu(dpz)(TBHP)]H2O (2) and [Cu(dppz)(TBHP)]H2O (3) (phen=1,10-phenanthroline, dpz=dipyrido [3,2:2',3'-f]quinoxaline, dppz=dipyrido [3,2-a:2',3'-c]phenazine, H2TBHP=2-(3,5-di-tert-butyl-2-hydroxybenzylamino)-2-benzyl-acetic acid). The DNA-binding properties of the complexes were investigated by spectrometric titrations, ethidium bromide displacement experiments and viscosity measurements. The results indicated that the three complexes, especially the complex 13, can strongly bind to calf-thymus DNA (CT-DNA). The intrinsic binding constants Kb of the ternary copper(II) complexes with CT-DNA were 1.37×10(5), 1.81×10(5) and 3.21×10(5) for 1, 2 and 3 respectively. Comparative cytotoxic activities of the copper(II) complexes were also determined by 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results showed that the ternary copper(II) complexes had significant cytotoxic activity against the human lung cancer (A549), human esophageal cancer (Eca109) and human gastric cancer (SGC7901) cell lines. Cell apoptosis were detected by AnnexinV/PI flow cytometry and by Western blotting with the protein expression of p53, Bax and Bcl-2. All the three copper complexes can effectively induce apoptosis of the three human tumor cells. Copyright © 2014 Elsevier Inc. All rights reserved.

High-performance ternary blend polymer solar cells involving both energy transfer and hole relay processes.

PubMed

Lu, Luyao; Chen, Wei; Xu, Tao; Yu, Luping

2015-06-04

The integration of multiple materials with complementary absorptions into a single junction device is regarded as an efficient way to enhance the power conversion efficiency (PCE) of organic solar cells (OSCs). However, because of increased complexity with one more component, only limited high-performance ternary systems have been demonstrated previously. Here we report an efficient ternary blend OSC with a PCE of 9.2%. We show that the third component can reduce surface trap densities in the ternary blend. Detailed studies unravel that the improved performance results from synergistic effects of enlarged open circuit voltage, suppressed trap-assisted recombination, enhanced light absorption, increased hole extraction, efficient energy transfer and better morphology. The working mechanism and high device performance demonstrate new insights and design guidelines for high-performance ternary blend solar cells and suggest that ternary structure is a promising platform to boost the efficiency of OSCs.

A lipid-binding loop of botulinum neurotoxin serotypes B, DC and G is an essential feature to confer their exquisite potency

PubMed Central

Le Blanc, Alexander; Mahrhold, Stefan; Piesker, Janett; Luppa, Peter B.

2018-01-01

The exceptional toxicity of botulinum neurotoxins (BoNTs) is mediated by high avidity binding to complex polysialogangliosides and intraluminal segments of synaptic vesicle proteins embedded in the presynaptic membrane. One peculiarity is an exposed hydrophobic loop in the toxin’s cell binding domain HC, which is located between the ganglioside- and protein receptor-binding sites, and that is particularly pronounced in the serotypes BoNT/B, DC, and G sharing synaptotagmin as protein receptor. Here, we provide evidence that this HC loop is a critical component of their tripartite receptor recognition complex. Binding to nanodisc-embedded receptors and toxicity were virtually abolished in BoNT mutants lacking residues at the tip of the HC loop. Surface plasmon resonance experiments revealed that only insertion of the HC loop into the lipid-bilayer compensates for the entropic penalty inflicted by the dual-receptor binding. Our results represent a new paradigm of how BoNT/B, DC, and G employ ternary interactions with a protein, ganglioside, and lipids to mediate their extraordinary neurotoxicity. PMID:29718991

Host-Guest Interaction of Cucurbit[8]uril with N-(3-Aminopropyl)cyclohexylamine: Cyclohexyl Encapsulation Triggered Ternary Complex.

PubMed

Xia, Yu; Wang, Chuan-Zeng; Tian, Mengkui; Tao, Zhu; Ni, Xin-Long; Prior, Timothy J; Redshaw, Carl

2018-01-15

The host-guest interaction of a series of cyclohexyl-appended guests with cucurbit[8]uril (Q[8]) was studied by ¹H NMR spectroscopy, isothermal titration calorimetry (ITC), and X-ray crystallography. The X-ray structure revealed that two cycloalkane moieties can be simultaneously encapsulated in the hydrophobic cavity of the Q[8] host to form a ternary complex for the first time.

Understanding the role of dynamics in the iron sulfur cluster molecular machine.

PubMed

di Maio, Danilo; Chandramouli, Balasubramanian; Yan, Robert; Brancato, Giuseppe; Pastore, Annalisa

2017-01-01

The bacterial proteins IscS, IscU and CyaY, the bacterial orthologue of frataxin, play an essential role in the biological machine that assembles the prosthetic FeS cluster groups on proteins. They form functionally binary and ternary complexes both in vivo and in vitro. Yet, the mechanism by which they work remains unclear. We carried out extensive molecular dynamics simulations to understand the nature of their interactions and the role of dynamics starting from the crystal structure of a IscS-IscU complex and the experimentally-based model of a ternary IscS-IscU-CyaY complex and used nuclear magnetic resonance to experimentally test the interface. We show that, while being firmly anchored to IscS, IscU has a pivotal motion around the interface. Our results also describe how the catalytic loop of IscS can flip conformation to allow FeS cluster assembly. This motion is hampered in the ternary complex explaining its inhibitory properties in cluster formation. We conclude that the observed 'fluid' IscS-IscU interface provides the binary complex with a functional adaptability exploited in partner recognition and unravels the molecular determinants of the reported inhibitory action of CyaY in the IscS-IscU-CyaY complex explained in terms of the hampering effect on specific IscU-IscS movements. Our study provides the first mechanistic basis to explain how the IscS-IscU complex selects its binding partners and supports the inhibitory role of CyaY in the ternary complex. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Modeling of multiple equilibria in the self-aggregation of di-n-decyldimethylammonium chloride/octaethylene glycol monododecyl ether/cyclodextrin ternary systems.

PubMed

Leclercq, Loïc; Lubart, Quentin; Aubry, Jean-Marie; Nardello-Rataj, Véronique

2013-05-28

The surface tension equations of binary surfactant mixtures (di-n-decyldimethylammonium chloride and octaethylene glycol monododecyl ether) are established by combining the Szyszkowski equation of surfactant solutions, the ideal or nonideal mixing theory, and the phase separation model. For surfactant mixtures, the surface tension at the air-water interface is calculated using nonideal theory due to synergism between the two adsorbed surfactant types. The incorporation of cyclodextrin complexation model to the surface tension equations gives a robust model for the description of the surface tension isotherms of binary, ternary, and more complex systems involving numerous inclusion complexes. The surface tension data obtained experimentally shows excellent agreement with the theoretical model below and above the formation of micelles. The strong synergistic effect observed between the two surfactants is disrupted by the presence of CDs, leading to ideal behavior of ternary systems. Indeed, depending on the nature of the cyclodextrin (i.e., α, β, or γ), which allows a tuning of the cavity size, the binding constants with the surfactants are modified as well as the surface properties due to strong modification of equilibria involved in the ternary mixture.

Spectral characterization of novel ternary zinc(II) complexes containing 1,10-phenanthroline and Schiff bases derived from amino acids and salicylaldehyde-5-sulfonates

NASA Astrophysics Data System (ADS)

Boghaei, Davar M.; Gharagozlou, Mehrnaz

2007-07-01

A series of new ternary zinc(II) complexes [Zn(L 1-10)(phen)], where phen is 1,10-phenanthroline and H 2L 1-10 = tridentate Schiff base ligands derived from the condensation of amino acids (glycine, L-phenylalanine, L-valine, L-alanine, and L-leucine) and salicylaldehyde-5-sulfonates (sodium salicylaldehyde-5-sulfonate and sodium 3-methoxy-salicylaldehyde-5-sulfonate), have been synthesized. The complexes were characterized by elemental analysis, IR, UV-vis, 1H NMR, and 13C NMR spectra. The IR spectra of the complexes showed large differences between νas(COO) and νs(COO), Δ ν ( νas(COO) - νs(COO)) of 191-225 cm -1, indicating a monodentate coordination of the carboxylate group. Spectral data showed that in these ternary complexes the zinc atom is coordinated with the Schiff base ligand acts as a tridentate ONO moiety, coordinating to the metal through its phenolic oxygen, imine nitrogen, and carboxyl oxygen, and also with the neutral planar chelating ligand, 1,10-phenanthroline, coordinating through nitrogens.

Adiabatic pipelining: a key to ternary computing with quantum dots.

PubMed

Pečar, P; Ramšak, A; Zimic, N; Mraz, M; Lebar Bajec, I

2008-12-10

The quantum-dot cellular automaton (QCA), a processing platform based on interacting quantum dots, was introduced by Lent in the mid-1990s. What followed was an exhilarating period with the development of the line, the functionally complete set of logic functions, as well as more complex processing structures, however all in the realm of binary logic. Regardless of these achievements, it has to be acknowledged that the use of binary logic is in computing systems mainly the end result of the technological limitations, which the designers had to cope with in the early days of their design. The first advancement of QCAs to multi-valued (ternary) processing was performed by Lebar Bajec et al, with the argument that processing platforms of the future should not disregard the clear advantages of multi-valued logic. Some of the elementary ternary QCAs, necessary for the construction of more complex processing entities, however, lead to a remarkable increase in size when compared to their binary counterparts. This somewhat negates the advantages gained by entering the ternary computing domain. As it turned out, even the binary QCA had its initial hiccups, which have been solved by the introduction of adiabatic switching and the application of adiabatic pipeline approaches. We present here a study that introduces adiabatic switching into the ternary QCA and employs the adiabatic pipeline approach to successfully solve the issues of elementary ternary QCAs. What is more, the ternary QCAs presented here are sizewise comparable to binary QCAs. This in our view might serve towards their faster adoption.

Structural characterization of environmentally relevant ternary uranyl citrate complexes present in aqueous solutions and solid state materials.

PubMed

Basile, Madeline; Unruh, Daniel K; Flores, Erin; Johns, Adam; Forbes, Tori Z

2015-02-14

Organic acids are important metal chelators in environmental systems and tend to form soluble complexes in aqueous solutions, ultimately influencing the transport and bioavailability of contaminants in surface and subsurface waters. This is particularly true for the formation of uranyl citrate complexes, which have been utilized in advanced photo- and bioremediation strategies for soils contaminated with nuclear materials. Given the complexity of environmental systems, the formation of ternary or heterometallic uranyl species in aqueous solutions are also expected, particularly with Al(iii) and Fe(iii) cations. These ternary forms are reported to be more stable in aqueous solutions, potentially enhancing contaminant mobility and uptake by organisms, but the exact coordination geometries of these soluble molecular complexes have not been elucidated. To provide insight into the nature of these species, we have developed a series of geochemical model compounds ([(UO(2))(2)Al(2)(C(6)H(4)O(7))(4)](6-) (U(2)Al(2)), [(UO(2))(2)Fe(2)(C(6)H(4)O(7))(4)](6-) (U(2)Fe(2)-1) and [(UO(2))(2)Fe(2)(C(6)H(4)O(7))(4)(H(2)O)(2)](6-) (U(2)Fe(2)-2) and [(UO(2))(2)Fe(4)(OH)(4)(C(6)H(4)O(7))(4)](8-) (U(2)Fe(4))) that were characterized by single-crystal X-ray diffraction and vibrational spectroscopy. Mass spectroscopy was then employed to compare the model compounds to species present in aqueous solutions to provide an enhanced understanding of the ternary uranyl citrate complexes that could be relevant in natural systems.

Role of an invariant lysine residue in folate binding on Escherichia coli thymidylate synthase: calorimetric and crystallographic analysis of the K48Q mutant

PubMed Central

Arvizu-Flores, Aldo A.; Sugich-Miranda, Rocio; Arreola, Rodrigo; Garcia-Orozco, Karina D.; Velazquez-Contreras, Enrique F.; Montfort, William R.; Maley, Frank; Sotelo-Mundo, Rogerio R.

2008-01-01

Thymidylate synthase (TS) catalyzes the reductive methylation of deoxyuridine monophosphate (dUMP) using methylene tetrahydrofolate (CH2THF) as cofactor, the glutamate tail of which forms a water-mediated hydrogen-bond with an invariant lysine residue of this enzyme. To understand the role of this interaction, we studied the K48Q mutant of Escherichia coli TS using structural and biophysical methods. The kcat of the K48Q mutant was 430 fold lower than wild-type TS in activity, while the the Km for the (R)-stereoisomer of CH2THF was 300 µM, about 30 fold larger than Km from the wild-type TS. Affinity constants were determined using isothermal titration calorimetry, which showed that binding was reduced by one order of magnitude for folate-like TS inhibitors, such as propargyl-dideaza folate (PDDF) or compounds that distort the TS active site like BW1843U89 (U89). The crystal structure of the K48Q-dUMP complex revealed that dUMP binding is not impaired in the mutamt, and that U89 in a ternary complex of K48Q-nucleotide-U89 was bound in the active site with subtle differences relative to comparable wild type complexes. PDDF failed to form ternary complexes with K48Q and dUMP. Thermodynamic data correlated with the structural determinations, since PDDF binding was dominated by enthalpic effects while U89 had an important entropic component. In conclusion, K48 is critical for catalysis since it leads to a productive CH2THF binding, while mutation at this residue does not affect much the binding of inhibitors that do not make contact with this group. PMID:18403248

DNA-HMGB1 interaction: The nuclear aggregates of polyamine mediation.

PubMed

Iacomino, Giuseppe; Picariello, Gianluca; Sbrana, Francesca; Raiteri, Roberto; D'Agostino, Luciano

2016-10-01

Nuclear aggregates of polyamines (NAPs) are supramolecular compounds generated by the self-assembly of protonated nuclear polyamines (spermine, spermidine and putrescine) and phosphate ions. In the presence of genomic DNA, the hierarchical process of self-structuring ultimately produces nanotube-like polymers that envelop the double helix. Because of their modular nature and their aggregation-disaggregation dynamics, NAPs confer plasticity and flexibility to DNA. Through the disposition of charges, NAPs also enable a bidirectional stream of information between the genome and interacting moieties. High mobility group (HMG) B1 is a non-histone chromosomal protein that binds to DNA and that influences multiple nuclear processes. Because genomic DNA binds to either NAPs or HMGB1 protein, we explored the ability of in vitro self-assembled NAPs (ivNAPs) to mediate the DNA-HMGB1 interaction. To this end, we structured DNA-NAPs-HMGB1 and DNA-HMGB1-NAPs ternary complexes in vitro through opportune sequential incubations. Mobility shift electrophoresis and atomic force microscopy showed that the DNA-ivNAPs-HGMB1 complex had conformational assets supposedly more suitable those of the DNA-HGMB1-ivNAPs to comply with the physiological and functional requirements of DNA. Our findings indicated that ivNAPs act as mediators of the DNA-HMGB1 interaction. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of the phase solubility diagram of a phenacetin/competitor/beta-cyclodextrin ternary system, involving competitive inclusion complexation.

PubMed

Ono, N; Hirayama, F; Arima, H; Uekama, K

2001-01-01

The competitive inclusion complexations in the ternary phenacetin/competitors/beta-cyclodextrin (beta-CyD) systems were investigated by the solubility method, where m-bromobenzoic acid (m-BBA) and o-toluic acid (o-TA) were used as competitors. The solubility changes of the drug and competitors as a function of beta-CyD concentration in the ternary systems were formulated using their stability constants and intrinsic solubilities. The decrease in solubility of phenacetin by the addition of competitors could be quantitatively simulated by the formulation, when both drug and competitor give A(L) type solubility diagrams. On the other hand, when one of the guests gives a B(S) type solubility diagram, its solubility change was clearly reflected in that of the another guest, i.e., phenacetin gave an A(L) type solubility diagram in the binary phenacetin/beta-CyD system and o-TA gave a B(S) type diagram in the binary o-TA/beta-CyD system, but in the ternary phenacetin/o-TA/beta-CyD system, a new plateau region appeared in the original A(L) type diagram of phenacetin. This was explained by the solubilization theory of Higuchi and Connors. The solubility analysis of the ternary drug/competitor/CyD systems may be particularly useful for determination of the stability constant of a drug whose physicochemical and spectroscopic analyses are difficult, because they can be calculated by monitoring the solubility change of a competitor, without monitoring that of a drug. Furthermore, the present results suggest that attention should be paid to the type of the phase solubility diagram, as well as the magnitude of the stability constant and the solubility of the complex, for a rational formulation design of CyD complexes.

Synthesis, structural characterization, in vitro antimicrobial and anticancer activity studies of ternary metal complexes containing glycine amino acid and the anti-inflammatory drug lornoxicam

NASA Astrophysics Data System (ADS)

Mahmoud, Walaa H.; Mohamed, Gehad G.; El-Dessouky, Maher M. I.

2015-02-01

Mixed ligand complexes were synthesized using lornoxicam (LOR) as the primary ligand and glycine amino acid (HGly) as the secondary ligand. They were characterized by FT-IR, UV-Vis, mass, 1H NMR, ESR spectral studies, TG-DTG, X-ray powder diffraction and physical analytical studies. From the molar conductance, magnetic moment and electronic spectral data of the synthesized complexes, general formulae of [M(LOR)2(Gly)]·Xn·yH2O where M = Cr(III) (X = Cl, n = 2, y = 3), Mn(II) (X = Cl, n = 1, y = 1), Co(II) (X = BF4, n = 1, y = 0), Ni(II) (X = Cl, n = 1, y = 0), Cu(II) (X = BF4, n = 1, y = 2) and Zn(II) (X = BF4, n = 1, y = 2) and (M = Fe(II) (X = BF4, n = 1, y = 1) and Fe(III) (X = Cl, n = 2, y = 1) with an octahedral structure were proposed. Thermal analyses show that the complexes lose water molecules of hydration initially and subsequently expel anionic parts and organic ligands in continuous steps. The kinetic parameters namely E, ΔH∗, ΔS∗ and ΔG∗ illustrate the spontaneous association of the metal and ligands in the formation of the complexes. The antimicrobial efficiency of the LOR and HGly ligands and the ternary complexes were examined by in vitro method against various pathogenic bacterial and fungal strains. The metal complexes were found to possess efficient antimicrobial properties compared to lornoxicam and most of these complexes could turn out to be excellent models for the design of effective antibiotic drug substances. Also, the two ligands, in comparison to ternary metal complexes are screened for their anticancer activity against breastic cancer cell line. The results showed that the metal complexes be more active than the parent LOR and glycine free ligands except Cr(III) ternary complex which was found to be inactive.

In situ molecular elucidation of drug supersaturation achieved by nano-sizing and amorphization of poorly water-soluble drug.

PubMed

Ueda, Keisuke; Higashi, Kenjirou; Yamamoto, Keiji; Moribe, Kunikazu

2015-09-18

Quantitative evaluation of drug supersaturation and nanoparticle formation was conducted using in situ evaluation techniques, including nuclear magnetic resonance (NMR) spectroscopy. We prepared a ternary complex of carbamazepine (CBZ) with hydroxypropyl methylcellulose (HPMC) and sodium dodecyl sulfate (SDS) to improve the drug concentration. Different preparation methods, including grinding and spray drying, were performed to prepare the ternary component products, ground mixture (GM) and spray-dried sample (SD), respectively. Although CBZ was completely amorphized in the ternary SD, CBZ was partially amorphized with the remaining CBZ crystals in the ternary GM. Aqueous dispersion of the ternary GM formed nanoparticles of around 150 nm, originating from the CBZ crystals in the ternary GM. In contrast, the ternary SD formed transparent solutions without a precipitate. The molecular-level evaluation using NMR measurements revealed that approximately half a dose of CBZ in the ternary GM dispersion was present as nanoparticles; however, CBZ in the ternary SD was completely dissolved in the aqueous solution. The characteristic difference between the solid states, followed by different preparation methods, induced different solution characteristics in the ternary GM and SD. The permeation study, using a dialysis membrane, showed that the CBZ concentration dissolved in the bulk water phase rapidly reduced in the ternary SD dispersion compared to the ternary GM dispersion; this demonstrated the advantage of ternary GM dispersion in the maintenance of CBZ supersaturation. Long-term maintenance of a supersaturated state of CBZ observed in the ternary GM dispersion rather than in the ternary SD dispersion was achieved by the inhibition of CBZ crystallization owing to the existence of CBZ nanoparticles in the ternary GM dispersion. Nanoparticle formation, combined with drug amorphization, could be a promising approach to improve drug concentrations. The detailed elucidation of solution characteristics using in situ evaluation techniques will lead to the formation of useful solid dispersion and nanoparticle formulations, resulting in improved drug absorption. Copyright © 2015 Elsevier B.V. All rights reserved.

Ternary metal complexes of guaifenesin drug: Synthesis, spectroscopic characterization and in vitro anticancer activity of the metal complexes.

PubMed

Mahmoud, W H; Mahmoud, N F; Mohamed, G G; El-Sonbati, A Z; El-Bindary, A A

2015-01-01

The coordination behavior of a series of transition metal ions named Cr(III), Fe(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with a mono negative tridentate guaifenesin ligand (GFS) (OOO donation sites) and 1,10-phenanthroline (Phen) is reported. The metal complexes are characterized based on elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance, UV-vis spectral studies, mass spectroscopy, ESR, XRD and thermal analysis (TG and DTG). The ternary metal complexes were found to have the formulae of [M(GFS)(Phen)Cl]Cl·nH2O (M=Cr(III) (n=1) and Fe(III) (n=0)), [M(GFS)(Phen)Cl]·nH2O (M=Mn(II) (n=0), Zn(II) (n=0) and Cu(II) (n=3)) and [M(GFS)(Phen)(H2O)]Cl·nH2O (M=Co(II) (n=0), Ni(II) (n=0) and Cd(II) (n=4)). All the chelates are found to have octahedral geometrical structures. The ligand and its ternary chelates are subjected to thermal analyses (TG and DTG). The GFS ligand, in comparison to its ternary metal complexes also was screened for their antibacterial activity on gram positive bacteria (Bacillus subtilis and Staphylococcus aureus), gram negative bacteria (Escherichia coli and Neisseria gonorrhoeae) and for in vitro antifungal activity against (Candida albicans). The activity data show that the metal complexes have antibacterial and antifungal activity more than the parent GFS ligand. The complexes were also screened for its in vitro anticancer activity against the Breast cell line (MFC7) and the results obtained show that they exhibit a considerable anticancer activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Inscuteable Regulates the Pins-Mud Spindle Orientation Pathway

PubMed Central

Mauser, Jonathon F.; Prehoda, Kenneth E.

2012-01-01

During asymmetric cell division, alignment of the mitotic spindle with the cell polarity axis ensures that the cleavage furrow separates fate determinants into distinct daughter cells. The protein Inscuteable (Insc) is thought to link cell polarity and spindle positioning in diverse systems by binding the polarity protein Bazooka (Baz; aka Par-3) and the spindle orienting protein Partner of Inscuteable (Pins; mPins or LGN in mammals). Here we investigate the mechanism of spindle orientation by the Insc-Pins complex. Previously, we defined two Pins spindle orientation pathways: a complex with Mushroom body defect (Mud; NuMA in mammals) is required for full activity, whereas binding to Discs large (Dlg) is sufficient for partial activity. In the current study, we have examined the role of Inscuteable in mediating downstream Pins-mediated spindle orientation pathways. We find that the Insc-Pins complex requires Gαi for partial activity and that the complex specifically recruits Dlg but not Mud. In vitro competition experiments revealed that Insc and Mud compete for binding to the Pins TPR motifs, while Dlg can form a ternary complex with Insc-Pins. Our results suggest that Insc does not passively couple polarity and spindle orientation but preferentially inhibits the Mud pathway, while allowing the Dlg pathway to remain active. Insc-regulated complex assembly may ensure that the spindle is attached to the cortex (via Dlg) before activation of spindle pulling forces by Dynein/Dynactin (via Mud). PMID:22253744

High-performance ternary blend polymer solar cells involving both energy transfer and hole relay processes

DOE PAGES

Lu, Luyao; Chen, Wei; Xu, Tao; ...

2015-06-04

The integration of multiple materials with complementary absorptions into a single junction device is regarded as an efficient way to enhance the power conversion efficiency (PCE) of organic solar cells (OSCs). However, because of increased complexity with one more component, only limited high-performance ternary systems have been demonstrated previously. Here we report an efficient ternary blend OSC with a PCE of 9.2%. We show that the third component can reduce surface trap densities in the ternary blend. Detailed studies unravel that the improved performance results from synergistic effects of enlarged open circuit voltage, suppressed trap-assisted recombination, enhanced light absorption, increasedmore » hole extraction, efficient energy transfer and better morphology. As a result, the working mechanism and high device performance demonstrate new insights and design guidelines for high-performance ternary blend solar cells and suggest that ternary structure is a promising platform to boost the efficiency of OSCs.« less

Alternative solution model for the ternary carbonate system CaCO3 - MgCO3 - FeCO3 - I. A ternary Bragg-Williams ordering model

USGS Publications Warehouse

McSwiggen, P.L.

1993-01-01

The minerals of the ternary carbonate system CaCO3 - MgCO3 - FeCO3 represent a complex series of solid solutions and ordering states. An understanding of those complexities requires a solution model that can both duplicate the subsolidus phase relationships and generate correct values for the activities. Such a solution model must account for the changes in the total energy of the system resulting from a change in the ordering state of the individual constituents. Various ordering models have been applied to binary carbonate systems, but no attempts have previously been made to model the ordering in the ternary system. This study derives a new set of equations that allow for the equilibrium degree of order to be calculated for a system involving three cations mixing on two sites, as in the case of the ternary carbonates. The method is based on the Bragg-Williams approach. From the degree of order, the mole fractions of the three cations in each of the two sites can be determined. Once the site occupancies have been established, a Margules-type mixing model can be used to determine the free energy of mixing in the solid solution and therefore the activities of the various components. ?? 1993 Springer-Verlag.

Studies of lysine cyclodeaminase from Streptomyces pristinaespiralis: Insights into the complex transition NAD+ state.

PubMed

Ying, Hanxiao; Wang, Jing; Shi, Ting; Zhao, Yilei; Wang, Xin; Ouyang, Pingkai; Chen, Kequan

2018-01-01

Lysine cyclodeaminase (LCD) catalyzes the piperidine ring formation in macrolide-pipecolate natural products metabolic pathways from a lysine substrate through a combination of cyclization and deamination. This enzyme belongs to a unique enzyme class, which uses NAD + as the catalytic prosthetic group instead of as the co-substrate. To understand the molecular details of NAD + functions in lysine cyclodeaminase, we have determined four ternary crystal structure complexes of LCD-NAD + with pipecolic acid (LCD-PA), lysine (LCD-LYS), and an intermediate (LCD-INT) as ligands at 2.26-, 2.00-, 2.17- and 1.80 Å resolutions, respectively. By combining computational studies, a NAD + -mediated "gate keeper" function involving NAD + /NADH and Arg49 that control the binding and entry of the ligand lysine was revealed, confirming the critical roles of NAD + in the substrate access process. Further, in the gate opening form, a substrate delivery tunnel between ε-carboxyl moiety of Glu264 and the α-carboxyl moiety of Asp236 was observed through a comparison of four structure complexes. The LCD structure details including NAD + -mediated "gate keeper" and substrate tunnel may assist in the exploration the NAD + function in this unique enzyme class, and in regulation of macrolide-pipecolate natural product synthesis. Copyright © 2017 Elsevier Inc. All rights reserved.

Complex formation equilibria of binary and ternary complexes involving 3,3-bis(1-methylimidazol-2yl)propionic acid and bio-relevant ligands as 1-aminocyclopropane carboxylic acid with reference to plant hormone

NASA Astrophysics Data System (ADS)

Shoukry, Mohamed M.; Hassan, Safaa S.

2014-01-01

The formation equilibria for the binary complexes of Cu(II) with 1-aminocyclopropane carboxylic acid (ACC) and 3,3-bis(1-methylimidazol-2-yl)propionic acid (BIMP) were investigated. ACC and BIMP form the complexes 1 1 0, 1 2 0 and 1 1 -1. The ternary complexes of Cu(II) with BIMP and biorelevant ligands as some selected amino acids, peptides and DNA constituents are formed in a stepwise mechanism. The stability constants of the complexes formed were determined and their distribution diagrams were evaluated. The kinetics of hydrolysis of glycine methyl ester in presence of [Cu(BIMP)]+ was investigated by pH-stat technique and the mechanism was discussed.

Insulin-like Growth Factor (IGF) Signaling Requires αvβ3-IGF1-IGF Type 1 Receptor (IGF1R) Ternary Complex Formation in Anchorage Independence, and the Complex Formation Does Not Require IGF1R and Src Activation

PubMed Central

Fujita, Masaaki; Takada, Yoko K.; Takada, Yoshikazu

2013-01-01

Integrin αvβ3 plays a role in insulin-like growth factor 1 (IGF1) signaling (integrin-IGF1 receptor (IGF1R) cross-talk) in non-transformed cells in anchorage-dependent conditions. We reported previously that IGF1 directly binds to αvβ3 and induces αvβ3-IGF1-IGF1R ternary complex formation in these conditions. The integrin-binding defective IGF1 mutant (R36E/R37E) is defective in inducing ternary complex formation and IGF signaling, whereas it still binds to IGF1R. We studied if IGF1 can induce signaling in anchorage-independent conditions in transformed Chinese hamster ovary cells that express αvβ3 (β3-CHO) cells. Here we describe that IGF1 signals were more clearly detectable in anchorage-independent conditions (polyHEMA-coated plates) than in anchorage-dependent conditions. This suggests that IGF signaling is masked by signals from cell-matrix interaction in anchorage-dependent conditions. IGF signaling required αvβ3 expression, and R36E/R37E was defective in inducing signals in polyHEMA-coated plates. These results suggest that αvβ3-IGF1 interaction, not αvβ3-extracellular matrix interaction, is essential for IGF signaling. Inhibitors of IGF1R, Src, AKT, and ERK1/2 did not suppress αvβ3-IGF-IGF1R ternary complex formation, suggesting that activation of these kinases are not required for ternary complex formation. Also, mutations of the β3 cytoplasmic tail (Y747F and Y759F) that block β3 tyrosine phosphorylation did not affect IGF1R phosphorylation or AKT activation. We propose a model in which IGF1 binding to IGF1R induces recruitment of integrin αvβ3 to the IGF-IGF1R complex and then β3 and IGF1R are phosphorylated. It is likely that αvβ3 should be together with the IGF1-IGF1R complex for triggering IGF signaling. PMID:23243309

Demonstration of long minority carrier lifetimes in very narrow bandgap ternary InAs/GaInSb superlattices

DOE PAGES

Olson, Benjamin Varberg; Kim, Jin K.; Kadlec, Emil Andrew; ...

2015-09-28

Minority carrier lifetimes in very long wavelength infrared (VLWIR) InAs/GaInSb superlattices (SLs) are reported using time-resolved microwave reflectance measurements. A strain-balanced ternary SL absorber layer of 47.0 Å InAs/21.5 Å Ga0.75In0.25Sb, corresponding to a bandgap of ~50 meV, is found to have a minority carrier lifetime of 140 ± 20 ns at ~18 K. This lifetime is extraordinarily long, when compared to lifetime values previously reported for other VLWIR SL detector materials. As a result, this enhancement is attributed to the strain-engineered ternary design, which offers a variety of epitaxial advantages and ultimately leads to a reduction of defect-mediated recombinationmore » centers.« less

Coordination properties of tridentate (N,O,O) heterocyclic alcohol (PDC) with Cu(II). Mixed ligand complex formation reactions of Cu(II) with PDC and some bio-relevant ligands.

PubMed

El-Sherif, Ahmed A; Shoukry, Mohamed M

2007-03-01

The formation equilibria of copper(II) complexes and the ternary complexes Cu(PDC)L (PDC=2,6-bis-(hydroxymethyl)-pyridine, HL=amino acid, amides or DNA constituents) have been investigated. Ternary complexes are formed by a simultaneous mechanism. The results showed the formation of Cu(PDC)L, Cu(PDC, H(-1))(L) and Cu(PDC, H(-2))(L) complexes. The concentration distribution of the complexes in solution is evaluated as a function of pH. The effect of dioxane as a solvent on the protonation constant of PDC and the formation constants of Cu(II) complexes are discussed. The thermodynamic parameters DeltaH degrees and DeltaS degrees calculated from the temperature dependence of the equilibrium constants are investigated.

A comparative study of the microstructures observed in statically cast and continuously cast Bi-In-Sn ternary eutectic alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sengupta, S.; Soda, H.; McLean, A.

2000-01-01

A ternary eutectic alloy with a composition of 57.2 pct Bi, 24.8 pct In, and 18 pct Sn was continuously cast into wire of 2 mm diameter with casting speeds of 14 and 79 mm/min using the Ohno Continuous Casting (OCC) process. The microstructures obtained were compared with those of statically cast specimens. Extensive segregation of massive Bi blocks, Bi complex structures, and tin-rich dendrites was found in specimens that were statically cast. Decomposition of {radical}Sn by a eutectoid reaction was confirmed based on microstructural evidence. Ternary eutectic alloy with a cooling rate of approximately 1 C/min formed a doublemore » binary eutectic. The double binary eutectic consisted of regions of BiIn and decomposed {radical}Sn in the form of a dendrite cell structure and regions of Bi and decomposed {radical}Sn in the form of a complex-regular cell. The Bi complex-regular cells, which are a ternary eutectic constituent, existed either along the boundaries of the BiIn-decomposed {radical}Sn dendrite cells or at the front of elongated dendrite cell structures. In the continuously cast wires, primary Sn dendrites coupled with a small Bi phase were uniformly distributed within the Bi-In alloy matrix. Neither massive Bi phase, Bi complex-regular cells, no BiIn eutectic dendrite cells were observed, resulting in a more uniform microstructure in contrast to the heavily segregated structures of the statically cast specimens.« less

Using AFM to probe the complexation of DNA with anionic lipids mediated by Ca(2+): the role of surface pressure.

PubMed

Luque-Caballero, Germán; Martín-Molina, Alberto; Sánchez-Treviño, Alda Yadira; Rodríguez-Valverde, Miguel A; Cabrerizo-Vílchez, Miguel A; Maldonado-Valderrama, Julia

2014-04-28

Complexation of DNA with lipids is currently being developed as an alternative to classical vectors based on viruses. Most of the research to date focuses on cationic lipids owing to their spontaneous complexation with DNA. Nonetheless, recent investigations have revealed that cationic lipids induce a large number of adverse effects on DNA delivery. Precisely, the lower cytotoxicity of anionic lipids accounts for their use as a promising alternative. However, the complexation of DNA with anionic lipids (mediated by cations) is still in early stages and is not yet well understood. In order to explore the molecular mechanisms underlying the complexation of anionic lipids and DNA we proposed a combined methodology based on the surface pressure-area isotherms, Gibbs elasticity and Atomic Force Microscopy (AFM). These techniques allow elucidation of the role of the surface pressure in the complexation and visualization of the interfacial aggregates for the first time. We demonstrate that the DNA complexes with negatively charged model monolayers (DPPC/DPPS 4 : 1) only in the presence of Ca(2+), but is expelled at very high surface pressures. Also, according to the Gibbs elasticity plot, the complexation of lipids and DNA implies a whole fluidisation of the monolayer and a completely different phase transition map in the presence of DNA and Ca(2+). AFM imaging allows identification for the first time of specific morphologies associated with different packing densities. At low surface coverage, a branched net like structure is observed whereas at high surface pressure fibers formed of interfacial aggregates appear. In summary, Ca(2+) mediates the interaction between DNA and negatively charged lipids and also the conformation of the ternary system depends on the surface pressure. Such observations are important new generic features of the interaction between DNA and anionic lipids.

Direct evidence of an elongation factor-Tu/Ts·GTP·Aminoacyl-tRNA quaternary complex.

PubMed

Burnett, Benjamin J; Altman, Roger B; Ferguson, Angelica; Wasserman, Michael R; Zhou, Zhou; Blanchard, Scott C

2014-08-22

During protein synthesis, elongation factor-Tu (EF-Tu) bound to GTP chaperones the entry of aminoacyl-tRNA (aa-tRNA) into actively translating ribosomes. In so doing, EF-Tu increases the rate and fidelity of the translation mechanism. Recent evidence suggests that EF-Ts, the guanosine nucleotide exchange factor for EF-Tu, directly accelerates both the formation and dissociation of the EF-Tu-GTP-Phe-tRNA(Phe) ternary complex (Burnett, B. J., Altman, R. B., Ferrao, R., Alejo, J. L., Kaur, N., Kanji, J., and Blanchard, S. C. (2013) J. Biol. Chem. 288, 13917-13928). A central feature of this model is the existence of a quaternary complex of EF-Tu/Ts·GTP·aa-tRNA(aa). Here, through comparative investigations of phenylalanyl, methionyl, and arginyl ternary complexes, and the development of a strategy to monitor their formation and decay using fluorescence resonance energy transfer, we reveal the generality of this newly described EF-Ts function and the first direct evidence of the transient quaternary complex species. These findings suggest that EF-Ts may regulate ternary complex abundance in the cell through mechanisms that are distinct from its guanosine nucleotide exchange factor functions. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Ternary complex formation of Eu(III) with o-phthalate in aqueous solutions.

PubMed

Park, K K; Jung, E C; Cho, H-R; Kim, W H

2009-08-15

Ternary hydroxo complex formation of Eu(III) with o-phthalate was investigated by potentiometry and fluorescence spectrophotometry. Curves of the equilibrium pH versus the amount of NaOH added showed that the pH value starting to form a Eu(III) precipitate was decreased due to the formation of a ternary hydroxo complex, EuOHL(s) (L = phthalate). The formation of EuOHL(s) was qualitatively confirmed by the enhancement of the fluorescence intensity of Eu(III) in the precipitate with the light absorbed by phthalate, and was quantitatively confirmed by the measurement of the amounts of Eu(III), OH(-) and phthalate included in the precipitate. The solubility product of EuOHL(s) was determined as pK(sp)(0) = 15.6+/-0.4. Characteristic features in the fluorescence spectra and the solubility product of the Eu(III)-phthalate complex were compared with those of the Eu(III)-PDA (PDA = pyridine-2,6-dicarboxylate) complex. The fluorescence intensity of the EuL(+) complex of L = PDA was about 11 times stronger than that of L = phthalate. The origin of the difference in the fluorescence intensity is discussed based on the intramolecular energy transfer effect from the lowest triplet energy level of the ligand to the resonance energy level of Eu(III).

Structural basis for the inhibition of insulin-like growth factors by insulin-like growth factor-binding proteins

PubMed Central

Sitar, Tomasz; Popowicz, Grzegorz M.; Siwanowicz, Igor; Huber, Robert; Holak, Tad A.

2006-01-01

Insulin-like growth factor-binding proteins (IGFBPs) control bioavailability, activity, and distribution of insulin-like growth factor (IGF)1 and -2 through high-affinity IGFBP/IGF complexes. IGF-binding sites are found on N- and C-terminal fragments of IGFBPs, the two conserved domains of IGFBPs. The relative contributions of these domains to IGFBP/IGF complexation has been difficult to analyze, in part, because of the lack of appropriate three-dimensional structures. To analyze the effects of N- and C-terminal domain interactions, we determined several x-ray structures: first, of a ternary complex of N- and C-terminal domain fragments of IGFBP4 and IGF1 and second, of a “hybrid” ternary complex using the C-terminal domain fragment of IGFBP1 instead of IGFBP4. We also solved the binary complex of the N-terminal domains of IGFBP4 and IGF1, again to analyze C- and N-terminal domain interactions by comparison with the ternary complexes. The structures reveal the mechanisms of IGF signaling regulation via IGFBP binding. This finding supports research into the design of IGFBP variants as therapeutic IGF inhibitors for diseases of IGF disregulation. In IGFBP4, residues 1–38 form a rigid disulphide bond ladder-like structure, and the first five N-terminal residues bind to IGF and partially mask IGF residues responsible for the type 1 IGF receptor binding. A high-affinity IGF1-binding site is located in a globular structure between residues 39 and 82. Although the C-terminal domains do not form stable binary complexes with either IGF1 or the N-terminal domain of IGFBP4, in the ternary complex, the C-terminal domain contacts both and contributes to blocking of the IGF1 receptor-binding region of IGF1. PMID:16924115

Theoretical study of X⁻ · 1 · YF (1 = triazine, X = Cl, Br and I, Y = H, Cl, Br, I, PH₂ and AsH₂): noncovalently electron-withdrawing effects on anion-arene interactions.

PubMed

Chen, Yishan; Yao, Lifeng

2014-01-01

The ternary complexes X(-) · 1 · YF (1 = triazine, X = Cl, Br and I, Y = H, Cl, Br, I, PH2 and AsH2) have been investigated by MP2 calculations to understand the noncovalently electron-withdrawing effects on anion-arene interactions. The results indicate that in binary complexes (1 · X(-)), both weak σ-type and anion-π complexes can be formed for Cl(-) and Br(-), but only anion-π complex can be formed for I(-). Moreover, the hydrogen-bonding complex is the global minimum for all three halides in binary complexes. However, in ternary complexes, anion-π complex become unstable and only σ complex can retain in many cases for Cl(-) and Br(-). Anion-π complex keeps stable only when YF = HF. In contrast with binary complexes, σ complex become the global minimum for Cl(-) and Br(-) in ternary complexes. These changes in binding mode and strength are consistent with the results of covalently electron-withdrawing effects. However, in contrast with the covalently electron-withdrawing substituents, Cl(-) and Br(-) can attack the aromatic carbon atom to form a strong σ complex when the noncovalently electron-withdrawing effect is induced by halogen bonding. The binding behavior for I(-) is different from that for Cl(-) and Br(-) in two aspects. First, the anion-π complex for I(-) can also keep stable when the noncovalent interaction is halogen bonding. Second, the anion-π complex for I(-) is the global minimum when it can retain as a stable structure.

Effect of Natural Organic Matter on Plutonium Sorption to Goethite

DOE PAGES

Conroy, Nathan A.; Zavarin, Mavrik; Kersting, Annie B.; ...

2016-11-21

For this research, the effect of citric acid (CA), desferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite was studied as a function of organic carbon concentration and pH using batch sorption experiments at 5 mg C·L –1 and 50 mg C·L –1 natural organic matter (NOM), 10 –9–10 –10 M 238Pu, and 0.1 g·L –1 goethite concentrations, at pH 3, 5, 7, and 9. Low sorption of ligands coupled with strong Pu complexation decreased Pu sorption at pH 5 and 7, relative to a ligand-free system. Conversely, CA, FA, and HA increasedmore » Pu sorption to goethite at pH 3, suggesting ternary complex formation or, in the case of humic acid, incorporation into HA aggregates. Mechanisms for ternary complex formation were characterized by Fourier transform infrared spectroscopy in the absence of Pu. CA and FA demonstrated clear surface interactions at pH 3, HA appeared unchanged suggesting HA aggregates had formed, and no DFOB interactions were observed. Plutonium sorption decreased in the presence of DFOB (relative to a ligand free system) at all pH values examined. Thus, DFOB does not appear to facilitate formation of ternary Pu-DFOB-goethite complexes. At pH 9, Pu sorption in the presence of all NOM increased relative to pH 5 and 7; speciation models attributed this to Pu(IV) hydrolysis competing with ligand complexation, increasing sorption. In conclusion, the results indicate that in simple Pu-NOM-goethite ternary batch systems, NOM will decrease Pu sorption to goethite at all but particularly low pH conditions.« less

Effect of Natural Organic Matter on Plutonium Sorption to Goethite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conroy, Nathan A.; Zavarin, Mavrik; Kersting, Annie B.

For this research, the effect of citric acid (CA), desferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite was studied as a function of organic carbon concentration and pH using batch sorption experiments at 5 mg C·L –1 and 50 mg C·L –1 natural organic matter (NOM), 10 –9–10 –10 M 238Pu, and 0.1 g·L –1 goethite concentrations, at pH 3, 5, 7, and 9. Low sorption of ligands coupled with strong Pu complexation decreased Pu sorption at pH 5 and 7, relative to a ligand-free system. Conversely, CA, FA, and HA increasedmore » Pu sorption to goethite at pH 3, suggesting ternary complex formation or, in the case of humic acid, incorporation into HA aggregates. Mechanisms for ternary complex formation were characterized by Fourier transform infrared spectroscopy in the absence of Pu. CA and FA demonstrated clear surface interactions at pH 3, HA appeared unchanged suggesting HA aggregates had formed, and no DFOB interactions were observed. Plutonium sorption decreased in the presence of DFOB (relative to a ligand free system) at all pH values examined. Thus, DFOB does not appear to facilitate formation of ternary Pu-DFOB-goethite complexes. At pH 9, Pu sorption in the presence of all NOM increased relative to pH 5 and 7; speciation models attributed this to Pu(IV) hydrolysis competing with ligand complexation, increasing sorption. In conclusion, the results indicate that in simple Pu-NOM-goethite ternary batch systems, NOM will decrease Pu sorption to goethite at all but particularly low pH conditions.« less

Analysis of physicochemical properties of ternary systems of oxaprozin with randomly methylated-ß-cyclodextrin and l-arginine aimed to improve the drug solubility.

PubMed

Mennini, Natascia; Maestrelli, Francesca; Cirri, Marzia; Mura, Paola

2016-09-10

The influence of l-arginine on the complexing and solubilizing power of randomly-methylated-β-cyclodextrin (RameβCD) towards oxaprozin, a very poorly soluble anti-inflammatory drug, was examined. The interactions between the components were investigated both in solution, by phase-solubility analysis, and in the solid state, by differential scanning calorimetry, FTIR and X-ray powder diffractometry. The morphology of the solid products was examined by Scanning Electron Microscopy. Results of phase-solubility studies indicated that addition of arginine enhanced the RameβCD complexing and solubilizing power of about 3.0 and 4.5 times, respectively, in comparison with the binary complex (both at pH≈6.8). The effect of arginine was not simply additive, but synergistic, being the ternary system solubility higher than the sum of those of the respective drug-CD and drug-arginine binary systems. Solid equimolar ternary systems were prepared by physical mixing, co-grinding, coevaporation and kneading techniques, to explore the effect of the preparation method on the physicochemical properties of the final products. The ternary co-ground product exhibited a dramatic increase in both drug dissolution efficiency and percent dissolved at 60min, whose values (83.6 and 97.1, respectively) were about 3 times higher than the sum of those given by the respective drug-CD and drug-aminoacid binary systems. Therefore, the ternary co-ground system with arginine and RameβCD appears as a very valuable product for the development of new more effective delivery systems of oxaprozin, with improved safety and bioavailability. Copyright © 2016 Elsevier B.V. All rights reserved.

Advanced Fault Diagnosis Methods in Molecular Networks

PubMed Central

Habibi, Iman; Emamian, Effat S.; Abdi, Ali

2014-01-01

Analysis of the failure of cell signaling networks is an important topic in systems biology and has applications in target discovery and drug development. In this paper, some advanced methods for fault diagnosis in signaling networks are developed and then applied to a caspase network and an SHP2 network. The goal is to understand how, and to what extent, the dysfunction of molecules in a network contributes to the failure of the entire network. Network dysfunction (failure) is defined as failure to produce the expected outputs in response to the input signals. Vulnerability level of a molecule is defined as the probability of the network failure, when the molecule is dysfunctional. In this study, a method to calculate the vulnerability level of single molecules for different combinations of input signals is developed. Furthermore, a more complex yet biologically meaningful method for calculating the multi-fault vulnerability levels is suggested, in which two or more molecules are simultaneously dysfunctional. Finally, a method is developed for fault diagnosis of networks based on a ternary logic model, which considers three activity levels for a molecule instead of the previously published binary logic model, and provides equations for the vulnerabilities of molecules in a ternary framework. Multi-fault analysis shows that the pairs of molecules with high vulnerability typically include a highly vulnerable molecule identified by the single fault analysis. The ternary fault analysis for the caspase network shows that predictions obtained using the more complex ternary model are about the same as the predictions of the simpler binary approach. This study suggests that by increasing the number of activity levels the complexity of the model grows; however, the predictive power of the ternary model does not appear to be increased proportionally. PMID:25290670

The Dynamics of the Human Leukocyte Antigen Head Domain Modulates Its Recognition by the T-Cell Receptor.

PubMed

García-Guerrero, Estefanía; Pérez-Simón, José Antonio; Sánchez-Abarca, Luis Ignacio; Díaz-Moreno, Irene; De la Rosa, Miguel A; Díaz-Quintana, Antonio

2016-01-01

Generating the immune response requires the discrimination of peptides presented by the human leukocyte antigen complex (HLA) through the T-cell receptor (TCR). However, how a single amino acid substitution in the antigen bonded to HLA affects the response of T cells remains uncertain. Hence, we used molecular dynamics computations to analyze the molecular interactions between peptides, HLA and TCR. We compared immunologically reactive complexes with non-reactive and weakly reactive complexes. MD trajectories were produced to simulate the behavior of isolated components of the various p-HLA-TCR complexes. Analysis of the fluctuations showed that p-HLA binding barely restrains TCR motions, and mainly affects the CDR3 loops. Conversely, inactive p-HLA complexes displayed significant drop in their dynamics when compared with its free versus ternary forms (p-HLA-TCR). In agreement, the free non-reactive p-HLA complexes showed a lower amount of salt bridges than the responsive ones. This resulted in differences between the electrostatic potentials of reactive and inactive p-HLA species and larger vibrational entropies in non-elicitor complexes. Analysis of the ternary p-HLA-TCR complexes also revealed a larger number of salt bridges in the responsive complexes. To summarize, our computations indicate that the affinity of each p-HLA complex towards TCR is intimately linked to both, the dynamics of its free species and its ability to form specific intermolecular salt-bridges in the ternary complexes. Of outstanding interest is the emerging concept of antigen reactivity involving its interplay with the HLA head sidechain dynamics by rearranging its salt-bridges.

Glass transition behavior of ternary disaccharide-ethylene glycol-water solutions

NASA Astrophysics Data System (ADS)

Yu, Tongxu; Zhao, Lishan; Wang, Qiang; Cao, Zexian

2017-06-01

Glass transition behavior of ternary disaccharide-ethylene glycol-water solutions, in reference to that of the binary combinations, has been investigated towards a better understanding of their cryoprotective ability. In water-deficient solutions, the disaccharides, including trehalose, sucrose and maltose, can associate with more than 100 ethylene glycol molecules to form amorphous complex, one order of magnitude larger than the corresponding hydration numbers. In water-rich solutions, a second glass transition emerges with increasing molar fraction of ethylene glycol, indicating the possible synergy of disaccharides and ethylene glycol in vitrification of the ternary aqueous solution.

Novel Optical Fiber Materials With Engineered Brillouin Gain Coefficients SSL 1: Novel Fiber Lasers

DTIC Science & Technology

2015-12-29

strontium aluminosilicate glasses . A zero-p12 composition is calculated to be at a SiO2 content of about 41.5 mol%, SrO content of about 22.5 mol...ternary, glasses that are needed for this program. These include the BaO- SiO2 system as an example binary glass , and the MgO-Al2O3- SiO2 and BaO-Al2O3... SiO2 systems as example ternary glasses (with the addition of a rare earth 16 resulting in a quaternary glass ). Complex ternary compositions were

G-actin provides substrate-specificity to eukaryotic initiation factor 2α holophosphatases

PubMed Central

Chen, Ruming; Rato, Cláudia; Yan, Yahui; Crespillo-Casado, Ana; Clarke, Hanna J; Harding, Heather P; Marciniak, Stefan J; Read, Randy J; Ron, David

2015-01-01

Dephosphorylation of eukaryotic translation initiation factor 2a (eIF2a) restores protein synthesis at the waning of stress responses and requires a PP1 catalytic subunit and a regulatory subunit, PPP1R15A/GADD34 or PPP1R15B/CReP. Surprisingly, PPP1R15-PP1 binary complexes reconstituted in vitro lacked substrate selectivity. However, selectivity was restored by crude cell lysate or purified G-actin, which joined PPP1R15-PP1 to form a stable ternary complex. In crystal structures of the non-selective PPP1R15B-PP1G complex, the functional core of PPP1R15 made multiple surface contacts with PP1G, but at a distance from the active site, whereas in the substrate-selective ternary complex, actin contributes to one face of a platform encompassing the active site. Computational docking of the N-terminal lobe of eIF2a at this platform placed phosphorylated serine 51 near the active site. Mutagenesis of predicted surface-contacting residues enfeebled dephosphorylation, suggesting that avidity for the substrate plays an important role in imparting specificity on the PPP1R15B-PP1G-actin ternary complex. DOI: http://dx.doi.org/10.7554/eLife.04871.001 PMID:25774600

Competitive and Cooperative Effects during Nickel Adsorption to Iron Oxides in the Presence of Oxalate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flynn, Elaine D.; Catalano, Jeffrey G.

Iron oxides are ubiquitous in soils and sediments and play a critical role in the geochemical distribution of trace elements and heavy metals via adsorption and coprecipitation. The presence of organic acids may potentially alter how metals associate with iron oxide minerals through a series of cooperative or competitive processes: solution complexation, ternary surface complexation, and surface site competition. The macroscopic and molecular-scale effects of these processes were investigated for Ni adsorption to hematite and goethite at pH 7 in the presence of oxalate. The addition of this organic acid suppresses Ni uptake on both minerals. Aqueous speciation suggests thatmore » this is dominantly the result of oxalate complexing and solubilizing Ni. Comparison of the Ni surface coverage to the concentration of free (uncomplexed) Ni 2+ in solution suggests that the oxalate also alters Ni adsorption affinity. EXAFS and ATR-FTIR spectroscopies indicate that these changes in binding affinity are due to the formation of Ni–oxalate ternary surface complexes. These observations demonstrate that competition between dissolved oxalate and the mineral surface for Ni overwhelms the enhancement in adsorption associated with ternary complexation. Oxalate thus largely enhances Ni mobility, thereby increasing micronutrient bioavailability and inhibiting contaminant sequestration.« less

Inhibition of the aggregation of lactoferrin and (-)-epigallocatechin gallate in the presence of polyphenols, oligosaccharides, and collagen peptide.

PubMed

Yang, Wei; Liu, Fuguo; Xu, Chenqi; Sun, Cuixia; Yuan, Fang; Gao, Yanxiang

2015-05-27

The aggregation of lactoferrin and (-)-epigallocatechin gallate (EGCG) was inhibited by polyphenols, oligosaccharides, and collagen peptide in this study. Polyphenols, oligosaccharides, or collagen peptide can effectively prevent the formation of lactoferrin-EGCG aggregates, respectively. The addition sequence of lactoferrin, polyphenols (oligosaccharides or collagen peptide) and EGCG can affect the turbidity and particle size of the ternary complexes in the buffer solution; however, it hardly affected the ζ-potential and fluorescence characteristics. With either positive or negative charge, polyphenols and collagen peptide disrupted the formation of lactoferrin-EGCG aggregate mainly through the mechanism of its competition with EGCG molecules which surrounded the lactoferrin molecule surface with weaker binding affinities, forming polyphenols or a collagen peptide-lactoferrin-EGCG ternary complex; for neutral oligosaccharides, the ternary complex was generated mainly through steric effects, accompanied by a change in the lactoferrin secondary structure induced by gallic acid, chlorogenic acid, and xylo-oligosaccharide. Polyphenols, oligosaccharides, or collagen peptide restraining the formation of lactoferrin-EGCG aggregate could be applied in the design of clear products in the food, pharmaceutical, and cosmetic industries.

Synthesis and photoluminescence properties of novel Schiff base type polymer-rare earth complexes containing furfural-based bidentate Schiff base ligands

NASA Astrophysics Data System (ADS)

Gao, Baojiao; Zhang, Dandan; Li, Yanbin

2018-03-01

Luminescent polymer-rare earth complexes are an important class of photoluminescence and electroluminescence materials. Via molecular design, two furfural-based bidentate Schiff base ligands, furfural-aniline (FA) type ligand and furfural-cyclohexylamine (FC) type ligand, were bonded on the side chains of polysulfone (PSF), respectively, forming two functionalized macromolecules, PSF-FA and PSF-FC. And then through respective coordination reactions of the two functionalized macromolecules with Eu(Ⅲ) ion and Tb(Ⅲ) ion, novel luminescent binary and ternary (with 1,10-phenanthroline as the second ligand) polymer-rare earth complexes were synthesized. For these complexes, on basis of the characterization of their chemical structures, they photoluminescence properties were main researched, and the relationship between their luminescent properties and structures was explored. The experimental results show that the complexes coming from PSF-FA and Eu(Ⅲ) ion including binary and ternary complexes emit strong red luminescence, indicating that the bonded bidentate Schiff base ligand FA can sensitize the fluorescence emission of Eu(III) ion. While the complexes coming from PSF-FC and Tb(Ⅲ) ion produce green luminescence, displaying that the bonded bidentate Schiff base ligand FC can sensitize the fluorescence emission of Tb(Ⅲ) ion. The fluorescence emission intensities of the ternary complexes were stronger than that of binary complexes, reflecting the important effect of the second ligand. The fluorescence emission of the solid film of complexes is much stronger than that of the solutions of complexes. Besides, by comparison, it is found that the furfural (as a heteroaromatic compound)-based Schiff base type polymer-rare earth complexes have stronger fluorescence emission and higher energy transfer efficiency than salicylaldehyde (as a common aromatic compound)-based Schiff base type polymer-rare earth complexes.

Spectral and thermal study of the ternary complexes of nickel with sulfasalazine and some amino acids

NASA Astrophysics Data System (ADS)

Soliman, Ahmed A.

2006-12-01

The ternary complexes of Ni(II) with sulfasalazine (H 3SS) as a primary ligand and alanine (ala), aspartic acid (asp), histidene (hist), methionine (meth) and serine (ser) amino acids as secondary ligands have been synthesized. Characterization of the complexes was based on elemental analyses, IR, UV-vis, mass spectra, magnetic moment and thermal analysis (TG). The isolated complexes were found to have the general formula [M(HSS)(AA)]4H 2O (AA = ala, asp, hist, meth, or ser amino acid) where nickel is tetra-coordinated. The thermal stability of the complexes was studied and the weight losses for the decomposition of the complexes were calculated and correlated with the mass fragmentation pattern. In most cases, the amino acid moiety is removed along with the Schiff base moiety leaving NiO as a metallic residue. The metallic residue was confirmed by powder XRD measurements.

Inner-sphere oxidation of ternary iminodiacetatochromium(III) complexes involving DL-valine and L-arginine as secondary ligands. Isokinetic relationship for the oxidation of ternary iminodiacetato-chromium(III) complexes by periodate.

PubMed

Ewais, Hassan A; Dahman, Faris D; Abdel-Khalek, Ahmed A

2009-02-04

In this paper, the kinetics of oxidation of [CrIII(HIDA)(Val)(H2O)2]+ and [CrIII(HIDA)(Arg)(H2O)2]+ (HIDA = iminodiacetic acid, Val = DL-valine and Arg = L-arginine) were studied. The choice of ternary complexes was attributed to two considerations. Firstly, in order to study the effect of the secondary ligands DL-valine and L-arginine on the stability of binary complex [CrIII(HIDA)(IDA)(H2O)] towards oxidation. Secondly, transition metal ternary complexes have received particular focus and have been employed in mapping protein surfaces as probes for biological redox centers and in protein capture for both purification and study. The results have shown that the reaction is first order with respect to both [IO4(-)] and the complex concentration, and the rate increases over the pH range 2.62 - 3.68 in both cases. The experimental rate law is consistent with a mechanism in which both the deprotonated forms of the complexes [CrIII(IDA)(Val)(H2O)2] and [CrIII(IDA)(Arg)(H2O)2] are significantly more reactive than the conjugate acids. The value of the intramolecular electron transfer rate constant for the oxidation of [CrIII(HIDA)(Arg)(H2O)2]+, k3 (1.82 x 10(-3) s(-1)), is greater than the value of k1 (1.22 x 10(-3) s(-1)) for the oxidation of [CrIII(HIDA)(Val)(H2O)2]+ at 45.0 degrees C and I = 0.20 mol dm(-3). It is proposed that electron transfer proceeds through an inner-sphere mechanism via coordination of IO4(-) to chromium(III). The oxidation of [CrIII(HIDA)(Val)(H2O)2]+ and [CrIII(HIDA)(Arg)(H2O)2]+ by periodate may proceed through an inner-sphere mechanism via two electron transfer giving chromium(VI). The value of the intramolecular electron transfer rate constant for the oxidation of [CrIII(HIDA)(Arg)(H2O)2]+, k3, is greater than the value of k1 for the oxidation of [CrIII(HIDA)(Val)(H2O)2]+. A common mechanism for the oxidation of ternary iminodiacetatochromium(III) complexes by periodate is proposed, and this is supported by an excellent isokinetic relationship between DeltaH* and DeltaS* values for these reactions.

Inner-sphere oxidation of ternary iminodiacetatochromium(III) complexes involving DL-valine and L-arginine as secondary ligands. Isokinetic relationship for the oxidation of ternary iminodiacetato-chromium(III) complexes by periodate

PubMed Central

Ewais, Hassan A; Dahman, Faris D; Abdel-Khalek, Ahmed A

2009-01-01

Background In this paper, the kinetics of oxidation of [CrIII(HIDA)(Val)(H2O)2]+ and [CrIII(HIDA)(Arg)(H2O)2]+ (HIDA = iminodiacetic acid, Val = DL-valine and Arg = L-arginine) were studied. The choice of ternary complexes was attributed to two considerations. Firstly, in order to study the effect of the secondary ligands DL-valine and L-arginine on the stability of binary complex [CrIII(HIDA)(IDA)(H2O)] towards oxidation. Secondly, transition metal ternary complexes have received particular focus and have been employed in mapping protein surfaces as probes for biological redox centers and in protein capture for both purification and study. Results The results have shown that the reaction is first order with respect to both [IO4-] and the complex concentration, and the rate increases over the pH range 2.62 – 3.68 in both cases. The experimental rate law is consistent with a mechanism in which both the deprotonated forms of the complexes [CrIII(IDA)(Val)(H2O)2] and [CrIII(IDA)(Arg)(H2O)2] are significantly more reactive than the conjugate acids. The value of the intramolecular electron transfer rate constant for the oxidation of [CrIII(HIDA)(Arg)(H2O)2]+, k3 (1.82 × 10-3 s-1), is greater than the value of k1 (1.22 × 10-3 s-1) for the oxidation of [CrIII(HIDA)(Val)(H2O)2]+ at 45.0°C and I = 0.20 mol dm-3. It is proposed that electron transfer proceeds through an inner-sphere mechanism via coordination of IO4- to chromium(III). Conclusion The oxidation of [CrIII(HIDA)(Val)(H2O)2]+ and [CrIII(HIDA)(Arg)(H2O)2]+ by periodate may proceed through an inner-sphere mechanism via two electron transfer giving chromium(VI). The value of the intramolecular electron transfer rate constant for the oxidation of [CrIII(HIDA)(Arg)(H2O)2]+, k3, is greater than the value of k1 for the oxidation of [CrIII(HIDA)(Val)(H2O)2]+. A common mechanism for the oxidation of ternary iminodiacetatochromium(III) complexes by periodate is proposed, and this is supported by an excellent isokinetic relationship between ΔH* and ΔS* values for these reactions. PMID:19193241

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cody, V.; Pace, J.; Rosowsky, A.

It has been shown that 2,4-diamino-6-arylmethylpteridines and 2,4-diamino-5-arylmethylpyrimidines containing an O-carboxylalkyloxy group in the aryl moiety are potent and selective inhibitors of the dihydrofolate reductase (DHFR) from opportunistic pathogens such as Pneumocystis carinii, the causative agent of Pneumocystis pneumonia in HIV/AIDS patients. In order to understand the structure-activity profile observed for a series of substituted dibenz[b,f]azepine antifolates, the crystal structures of mouse DHFR (mDHFR; a mammalian homologue) holo and ternary complexes with NADPH and the inhibitor 2,4-diamino-6-(2{prime}-hydroxydibenz[b,f]azepin-5-yl)methylpteridine were determined to 1.9 and 1.4 A resolution, respectively. Structural data for the ternary complex with the potent O-(3-carboxypropyl) inhibitor PT684 revealed nomore » electron density for the O-carboxylalkyloxy side chain. The side chain was either cleaved or completely disordered. The electron density fitted the less potent hydroxyl compound PT684a. Additionally, cocrystallization of mDHFR with NADPH and the less potent 2{prime}-(4-carboxybenzyl) inhibitor PT682 showed no electron density for the inhibitor and resulted in the first report of a holoenzyme complex despite several attempts at crystallization of a ternary complex. Modeling data of PT682 in the active site of mDHFR and P. carinii DHFR (pcDHFR) indicate that binding would require ligand-induced conformational changes to the enzyme for the inhibitor to fit into the active site or that the inhibitor side chain would have to adopt an alternative binding mode to that observed for other carboxyalkyloxy inhibitors. These data also show that the mDHFR complexes have a decreased active-site volume as reflected in the relative shift of helix C (residues 59-64) by 0.6 A compared with pcDHFR ternary complexes. These data are consistent with the greater inhibitory potency against pcDHFR.« less

Structure of the inhibitory region of troponin by site directed spin labeling electron paramagnetic resonance

PubMed Central

Brown, Louise J.; Sale, Ken L.; Hills, Ron; Rouviere, Clement; Song, Likai; Zhang, Xiaojun; Fajer, Piotr G.

2002-01-01

Site-directed spin labeling EPR (SDSL-EPR) was used to determine the structure of the inhibitory region of TnI in the intact cardiac troponin ternary complex. Maeda and collaborators have modeled the inhibitory region of TnI (skeletal 96–112: the structural motif that communicates the Ca2+ signal to actin) as a kinked α-helix [Vassylyev, D., Takeda, S., Wakatsuki, S., Maeda, K. & Maeda, Y. (1998) Proc. Natl. Acad. Sci. USA 95, 4847–4852), whereas Trewhella and collaborators have proposed the same region to be a flexible β-hairpin [Tung, C. S., Wall, M. E., Gallagher, S. C. & Trewhella, J. (2000) Protein Sci. 9, 1312–1326]. To distinguish between the two models, residues 129–145 of cardiac TnI were mutated sequentially to cysteines and labeled with the extrinsic spin probe, MTSSL. Sequence-dependent solvent accessibility was measured as a change in power saturation of the spin probe in the presence of the relaxation agent. In the ternary complex, the 129–137 region followed a pattern characteristic of a regular 3.6 residues/turn α-helix. The following region, residues 138–145, showed no regular pattern in solvent accessibility. Measurements of 4 intradomain distances within the inhibitory sequence, using dipolar EPR, were consistent with an α-helical structure. The difference in side-chain mobility between the ternary (C⋅I⋅T) and binary (C⋅I) complexes revealed a region of interaction of TnT located at the N-terminal end of the inhibitory sequence, residues 130–135. The above findings for the troponin complex in solution do not support either of the computational models of the binary complex; however, they are in very good agreement with a preliminary report of the x-ray structure of the cardiac ternary complex [Takeda, S. Yamashita, A., Maeda, K. & Maeda, Y. (2002) Biophys. J. 82, 832]. PMID:12239350

A novel DPP6 isoform (DPP6-E) can account for differences between neuronal and reconstituted A-type K(+) channels.

PubMed

Maffie, Jonathon; Blenkinsop, Timothy; Rudy, Bernardo

2009-01-16

The channels mediating most of the somatodendritic A-type K(+) current in neurons are thought to be ternary complexes of Kv4 pore-forming subunits and two types of auxiliary subunits, the K(+) channel interacting proteins (KChIPs) and dipeptidyl-peptidase-like (DPPL) proteins. The channels expressed in heterologous expression systems by mixtures of Kv4.2, KChIP1 and DPP6-S resemble in many properties the A-type current in hippocampal CA1 pyramidal neurons and cerebellar granule cells, neurons with prominent A-type K(+) currents. However, the native currents have faster kinetics. Moreover, the A-type currents in neurons in intermediary layers of the superior colliculus have even faster inactivating rates. We have characterized a new DPP6 spliced isoform, DPP6-E, that produces in heterologous cells ternary Kv4 channels with very fast kinetics. DPP6-E is selectively expressed in a few neuronal populations in brain including cerebellar granule neurons, hippocampal pyramidal cells and neurons in intermediary layers of the superior colliculus. The effects of DPP6-E explain past discrepancies between reconstituted and native Kv4 channels in some neurons, and contributes to the diversity of A-type K(+) currents in neurons.

Electrodeposition of amorphous ternary nickel-chromium-phosphorus alloy

DOEpatents

Guilinger, Terry R.

1990-01-01

Amorphous ternary nickel-chromium-phosphorus alloys are electrodeposited from a bath comprising a nickel salt, a chromium salt, a phosphorus source such as sodium hypophosphite, a complexing agent for the nickel ions, supporting salts to increase conductivity, and a buffering agent. The process is carried out at about room temperature and requires a current density between about 20 to 40 A/dm.sup.2.

Net (ERP/SAP2) one of the Ras-inducible TCFs, has a novel inhibitory domain with resemblance to the helix-loop-helix motif.

PubMed Central

Maira, S M; Wurtz, J M; Wasylyk, B

1996-01-01

The three ternary complex factors (TCFs), Net (ERP/ SAP-2), ELK-1 and SAP-1, are highly related ets oncogene family members that participate in the response of the cell to Ras and growth signals. Understanding the different roles of these factors will provide insights into how the signals result in coordinate regulation of the cell. We show that Net inhibits transcription under basal conditions, in which SAP-1a is inactive and ELK-1 stimulates. Repression is mediated by the NID, the Net Inhibitory Domain of about 50 amino acids, which autoregulates the Net protein and also inhibits when it is isolated in a heterologous fusion protein. Net is particularly sensitive to Ras activation. Ras activates Net through the C-domain, which is conserved between the three TCFs, and the NID is an efficient inhibitor of Ras activation. The NID, as well as more C-terminal sequences, inhibit DNA binding. Net is more refractory to DNA binding than the other TCFs, possibly due to the presence of multiple inhibitory elements. The NID may adopt a helix-loop-helix (HLH) structure, as evidenced by homology to other HLH motifs, structure predictions, model building and mutagenesis of critical residues. The sequence resemblance with myogenic factors suggested that Net may form complexes with the same partners. Indeed, we found that Net can interact in vivo with the basic HLH factor, E47. We propose that Net is regulated at the level of its latent DNA-binding activity by protein interactions and/or phosphorylation. Net may form complexes with HLH proteins as well as SRF on specific promotor sequences. The identification of the novel inhibitory domain provides a new inroad into exploring the different roles of the ternary complex factors in growth control and transformation. Images PMID:8918463

Net (ERP/SAP2) one of the Ras-inducible TCFs, has a novel inhibitory domain with resemblance to the helix-loop-helix motif.

PubMed

Maira, S M; Wurtz, J M; Wasylyk, B

1996-11-01

The three ternary complex factors (TCFs), Net (ERP/ SAP-2), ELK-1 and SAP-1, are highly related ets oncogene family members that participate in the response of the cell to Ras and growth signals. Understanding the different roles of these factors will provide insights into how the signals result in coordinate regulation of the cell. We show that Net inhibits transcription under basal conditions, in which SAP-1a is inactive and ELK-1 stimulates. Repression is mediated by the NID, the Net Inhibitory Domain of about 50 amino acids, which autoregulates the Net protein and also inhibits when it is isolated in a heterologous fusion protein. Net is particularly sensitive to Ras activation. Ras activates Net through the C-domain, which is conserved between the three TCFs, and the NID is an efficient inhibitor of Ras activation. The NID, as well as more C-terminal sequences, inhibit DNA binding. Net is more refractory to DNA binding than the other TCFs, possibly due to the presence of multiple inhibitory elements. The NID may adopt a helix-loop-helix (HLH) structure, as evidenced by homology to other HLH motifs, structure predictions, model building and mutagenesis of critical residues. The sequence resemblance with myogenic factors suggested that Net may form complexes with the same partners. Indeed, we found that Net can interact in vivo with the basic HLH factor, E47. We propose that Net is regulated at the level of its latent DNA-binding activity by protein interactions and/or phosphorylation. Net may form complexes with HLH proteins as well as SRF on specific promotor sequences. The identification of the novel inhibitory domain provides a new inroad into exploring the different roles of the ternary complex factors in growth control and transformation.

Following DNA chain extension and protein conformational changes in crystals of a Y-family DNA polymerase via Raman crystallography.

PubMed

Espinoza-Herrera, Shirly J; Gaur, Vineet; Suo, Zucai; Carey, Paul R

2013-07-23

Y-Family DNA polymerases are known to bypass DNA lesions in vitro and in vivo. Sulfolobus solfataricus DNA polymerase (Dpo4) was chosen as a model Y-family enzyme for investigating the mechanism of DNA synthesis in single crystals. Crystals of Dpo4 in complexes with DNA (the binary complex) in the presence or absence of an incoming nucleotide were analyzed by Raman microscopy. (13)C- and (15)N-labeled d*CTP, or unlabeled dCTP, were soaked into the binary crystals with G as the templating base. In the presence of the catalytic metal ions, Mg(2+) and Mn(2+), nucleotide incorporation was detected by the disappearance of the triphosphate band of dCTP and the retention of *C modes in the crystal following soaking out of noncovalently bound C(or *C)TP. The addition of the second coded base, thymine, was observed by adding cognate dTTP to the crystal following a single d*CTP addition. Adding these two bases caused visible damage to the crystal that was possibly caused by protein and/or DNA conformational change within the crystal. When d*CTP is soaked into the Dpo4 crystal in the absence of Mn(2+) or Mg(2+), the primer extension reaction did not occur; instead, a ternary protein·template·d*CTP complex was formed. In the Raman difference spectra of both binary and ternary complexes, in addition to the modes of d(*C)CTP, features caused by ring modes from the template/primer bases being perturbed and from the DNA backbone appear, as well as features from perturbed peptide and amino acid side chain modes. These effects are more pronounced in the ternary complex than in the binary complex. Using standardized Raman intensities followed as a function of time, the C(*C)TP population in the crystal was maximal at ∼20 min. These remained unchanged in the ternary complex but declined in the binary complexes as chain incorporation occurred.

Formation of ternary CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) complexes under neutral to weakly alkaline conditions.

PubMed

Lee, Jun-Yeop; Yun, Jong-Il

2013-07-21

The chemical behavior of ternary Ca-UO2-CO3 complexes was investigated by using time-resolved laser fluorescence spectroscopy (TRLFS) in combination with EDTA complexation at pH 7-9. A novel TRLFS revealed two distinct fluorescence lifetimes of 12.7 ± 0.2 ns and 29.2 ± 0.4 ns for uranyl complexes which were formed increasingly dependent upon the calcium ion concentration, even though nearly indistinguishable fluorescence peak shapes and positions were measured for both Ca-UO2-CO3 complexes. For identifying the stoichiometric number of complexed calcium ions, slope analysis in terms of relative fluorescence intensity versus calcium concentration was employed in a combination with the complexation reaction of CaEDTA(2-) by adding EDTA. The formation of CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) was identified under given conditions and their formation constants were determined at I = 0.1 M Na/HClO4 medium, and extrapolated to infinitely dilute solution using specific ion interaction theory (SIT). As a result, the formation constants for CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) were found to be log β113(0) = 27.27 ± 0.14 and log β213(0) = 29.81 ± 0.19, respectively, providing that the ternary Ca-UO2-CO3 complexes were predominant uranium(vi) species at neutral to weakly alkaline pH in the presence of Ca(2+) and CO3(2-) ions.

Species specific substrates and products choices of 4-O-acetyltransferase from Trichoderma brevicompactum.

PubMed

Sharma, Shikha; Kumari, Indu; Hussain, Razak; Ahmed, Mushtaq; Akhter, Yusuf

2017-09-01

Antagonistic species of Trichoderma such as T. harzianum, T. viride, T. virens and T. koningii are well-known biocontrol agents that have been reported to suppress pathogenic soil microbes and enhance the growth of crop plants. Secondary metabolites (SMs) including trichothecenes are responsible for its biocontrol activities. The trichothecenes, trichodermin and harzianum A (HA) are produced in species dependent manner respectively, by Trichoderma brevicompactum (TB) and Trichoderma arundinaceum (TA). The last step in the pathway involves the conversion of trichodermol into trichodermin or HA alternatively, which is catalyzed by 4-O-acetyltransferase (encoded by tri3 gene). Comparative sequence analysis of acetyltransferase enzyme of TB with other chloramphenicol acetyltransferase (CAT) family proteins revealed the conserved motif involved in the catalysis. Multiple substrate binding studies were carried out to explore the mechanism behind the two different outcomes. His188 was found to have a role in initial substrate binding. In the case of trichodermin synthesis, represented by ternary complex 1, the trichodermol and acetic anhydride (AAn), the two substrates come very close to each other during molecular simulation analysis so that interactions become possible between them and acetyl group may get transferred from AAn to trichodermol, and Tyr476 residue mediates this phenomenon resulting in the formation of trichodermin. However, in case of the HA biosynthesis using the TB version of enzyme, represented by ternary complex 2, the two substrates, trichodermol and octa-2Z,4E,6E-trienedioic acid (OCTA) did not show any such interactions. Copyright © 2017 Elsevier Inc. All rights reserved.

A pivotal role for reductive methylation in the de novo crystallization of a ternary complex composed of Yersinia pestis virulence factors YopN, SycN and YscB.

PubMed

Schubot, Florian D; Waugh, David S

2004-11-01

Structural studies of a ternary complex composed of the Yersina pestis virulence factors YopN, SycN and YscB were initially hampered by poor solubility of the individual proteins. Co-expression of all three proteins in Escherichia coli yielded a well behaved complex, but this sample proved to be recalcitrant to crystallization. As crystallization efforts remained fruitless, even after the proteolysis-guided engineering of a truncated YopN polypeptide, reductive methylation of lysine residues was employed to alter the surface properties of the complex. The methylated complex yielded crystals that diffracted X-rays to a maximal resolution of 1.8 A. The potential utility of reductive methylation as a remedial strategy for high-throughput structural biology was further underscored by the successful modification of a selenomethionine-substituted sample.

An unexpected phosphate binding site in Glyceraldehyde 3-Phosphate Dehydrogenase: Crystal structures of apo, holo and ternary complex of Cryptosporidium parvum enzyme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, William J; Senkovich, Olga; Chattopadhyay, Debasish

2009-06-08

The structure, function and reaction mechanism of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) have been extensively studied. Based on these studies, three anion binding sites have been identified, one 'Ps' site (for binding the C-3 phosphate of the substrate) and two sites, 'Pi' and 'new Pi', for inorganic phosphate. According to the original flip-flop model, the substrate phosphate group switches from the 'Pi' to the 'Ps' site during the multistep reaction. In light of the discovery of the 'new Pi' site, a modified flip-flop mechanism, in which the C-3 phosphate of the substrate binds to the 'new Pi' site and flips tomore » the 'Ps' site before the hydride transfer, was proposed. An alternative model based on a number of structures of B. stearothermophilus GAPDH ternary complexes (non-covalent and thioacyl intermediate) proposes that in the ternary Michaelis complex the C-3 phosphate binds to the 'Ps' site and flips from the 'Ps' to the 'new Pi' site during or after the redox step. We determined the crystal structure of Cryptosporidium parvum GAPDH in the apo and holo (enzyme + NAD) state and the structure of the ternary enzyme-cofactor-substrate complex using an active site mutant enzyme. The C. parvum GAPDH complex was prepared by pre-incubating the enzyme with substrate and cofactor, thereby allowing free movement of the protein structure and substrate molecules during their initial encounter. Sulfate and phosphate ions were excluded from purification and crystallization steps. The quality of the electron density map at 2{angstrom} resolution allowed unambiguous positioning of the substrate. In three subunits of the homotetramer the C-3 phosphate group of the non-covalently bound substrate is in the 'new Pi' site. A concomitant movement of the phosphate binding loop is observed in these three subunits. In the fourth subunit the C-3 phosphate occupies an unexpected site not seen before and the phosphate binding loop remains in the substrate-free conformation. Orientation of the substrate with respect to the active site histidine and serine (in the mutant enzyme) also varies in different subunits. The structures of the C. parvum GAPDH ternary complex and other GAPDH complexes demonstrate the plasticity of the substrate binding site. We propose that the active site of GAPDH can accommodate the substrate in multiple conformations at multiple locations during the initial encounter. However, the C-3 phosphate group clearly prefers the 'new Pi' site for initial binding in the active site.« less

Structural Basis for Nucleotide Binding and Reaction Catalysis in Mevalonate Diphosphate Decarboxylase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barta, Michael L.; McWhorter, William J.; Miziorko, Henry M.

2012-09-17

Mevalonate diphosphate decarboxylase (MDD) catalyzes the final step of the mevalonate pathway, the Mg{sup 2+}-ATP dependent decarboxylation of mevalonate 5-diphosphate (MVAPP), producing isopentenyl diphosphate (IPP). Synthesis of IPP, an isoprenoid precursor molecule that is a critical intermediate in peptidoglycan and polyisoprenoid biosynthesis, is essential in Gram-positive bacteria (e.g., Staphylococcus, Streptococcus, and Enterococcus spp.), and thus the enzymes of the mevalonate pathway are ideal antimicrobial targets. MDD belongs to the GHMP superfamily of metabolite kinases that have been extensively studied for the past 50 years, yet the crystallization of GHMP kinase ternary complexes has proven to be difficult. To further ourmore » understanding of the catalytic mechanism of GHMP kinases with the purpose of developing broad spectrum antimicrobial agents that target the substrate and nucleotide binding sites, we report the crystal structures of wild-type and mutant (S192A and D283A) ternary complexes of Staphylococcus epidermidis MDD. Comparison of apo, MVAPP-bound, and ternary complex wild-type MDD provides structural information about the mode of substrate binding and the catalytic mechanism. Structural characterization of ternary complexes of catalytically deficient MDD S192A and D283A (k{sub cat} decreased 10{sup 3}- and 10{sup 5}-fold, respectively) provides insight into MDD function. The carboxylate side chain of invariant Asp{sup 283} functions as a catalytic base and is essential for the proper orientation of the MVAPP C3-hydroxyl group within the active site funnel. Several MDD amino acids within the conserved phosphate binding loop ('P-loop') provide key interactions, stabilizing the nucleotide triphosphoryl moiety. The crystal structures presented here provide a useful foundation for structure-based drug design.« less

Crystal structures of the ternary complex of APH(4)-Ia/Hph with hygromycin B and an ATP analog using a thermostable mutant.

PubMed

Iino, Daisuke; Takakura, Yasuaki; Fukano, Kazuhiro; Sasaki, Yasuyuki; Hoshino, Takayuki; Ohsawa, Kanju; Nakamura, Akira; Yajima, Shunsuke

2013-07-01

Aminoglycoside 4-phosphotransferase-Ia (APH(4)-Ia)/Hygromycin B phosphotransferase (Hph) inactivates the aminoglycoside antibiotic hygromycin B (hygB) via phosphorylation. The crystal structure of the binary complex of APH(4)-Ia with hygB was recently reported. To characterize substrate recognition by the enzyme, we determined the crystal structure of the ternary complex of non-hydrolyzable ATP analog AMP-PNP and hygB with wild-type, thermostable Hph mutant Hph5, and apo-mutant enzyme forms. The comparison between the ternary complex and apo structures revealed that Hph undergoes domain movement upon binding of AMP-PNP and hygB. This was about half amount of the case of APH(9)-Ia. We also determined the crystal structures of mutants in which the conserved, catalytically important residues Asp198 and Asn203, and the non-conserved Asn202, were converted to Ala, revealing the importance of Asn202 for catalysis. Hph5 contains five amino acid substitutions that alter its thermostability by 16°C; its structure revealed that 4/5 mutations in Hph5 are located in the hydrophobic core and appear to increase thermostability by strengthening hydrophobic interactions. Copyright © 2013 Elsevier Inc. All rights reserved.

Detection of DNA via the fluorescence quenching of Mn-doped ZnSe D-dots/doxorubicin/DNA ternary complexes system.

PubMed

Gao, Xue; Niu, Lu; Su, Xingguang

2012-01-01

This manuscript reports a method for the detection of double-stranded DNA, based on Mn:ZnSe d-dots and intercalating agent doxorubicin (DOX). DOX can quench the photoluminescence (PL) of Mn:ZnSe d-dots through photoinduced electron transfer process, after binding with Mn:ZnSe d-dots. The addition of DNA can result in the formation of the Mn:ZnSe d-dots-DOX-DNA ternary complexes, the fluorescence of the Mn:ZnSe d-dots-DOX complexes would be further quenched by the addition of DNA, thus allowing the detection of DNA. The formation mechanism of the Mn:ZnSe d-dots-DOX-DNA ternary complexes was studied in detail in this paper. Under optimal conditions, the quenched fluorescence intensity of Mn:ZnSe d-dots-DOX system are perfectly described by Stern-Volmer equation with the concentration of hsDNA ranging from 0.006 μg mL(-1) to 6.4 μg mL(-1). The detection limit (S/N = 3) for hsDNA is 0.5 ng mL(-1). The proposed method was successfully applied to the detection of DNA in synthetic samples and the results were satisfactory.

An improved ternary vector system for Agrobacterium-mediated rapid maize transformation.

PubMed

Anand, Ajith; Bass, Steven H; Wu, Emily; Wang, Ning; McBride, Kevin E; Annaluru, Narayana; Miller, Michael; Hua, Mo; Jones, Todd J

2018-05-01

A simple and versatile ternary vector system that utilizes improved accessory plasmids for rapid maize transformation is described. This system facilitates high-throughput vector construction and plant transformation. The super binary plasmid pSB1 is a mainstay of maize transformation. However, the large size of the base vector makes it challenging to clone, the process of co-integration is cumbersome and inefficient, and some Agrobacterium strains are known to give rise to spontaneous mutants resistant to tetracycline. These limitations present substantial barriers to high throughput vector construction. Here we describe a smaller, simpler and versatile ternary vector system for maize transformation that utilizes improved accessory plasmids requiring no co-integration step. In addition, the newly described accessory plasmids have restored virulence genes found to be defective in pSB1, as well as added virulence genes. Testing of different configurations of the accessory plasmids in combination with T-DNA binary vector as ternary vectors nearly doubles both the raw transformation frequency and the number of transformation events of usable quality in difficult-to-transform maize inbreds. The newly described ternary vectors enabled the development of a rapid maize transformation method for elite inbreds. This vector system facilitated screening different origins of replication on the accessory plasmid and T-DNA vector, and four combinations were identified that have high (86-103%) raw transformation frequency in an elite maize inbred.

Characterization of WY 14,643 and its Complex with Aldose Reductase

PubMed Central

Sawaya, Michael R.; Verma, Malkhey; Balendiran, Vaishnavi; Rath, Nigam P.; Cascio, Duilio; Balendiran, Ganesaratnam K.

2016-01-01

The peroxisome proliferator, WY 14,643 exhibits a pure non-competitive inhibition pattern in the aldehyde reduction and in alcohol oxidation activities of human Aldose reductase (hAR). Fluorescence emission measurements of the equilibrium dissociation constants, Kd, of oxidized (hAR•NADP+) and reduced (hAR•NADPH) holoenzyme complexes display a 2-fold difference between them. Kd values for the dissociation of WY 14,643 from the oxidized (hAR•NADP+•WY 14,643) and reduced (hAR•NADPH•WY 14,643) ternary complexes are comparable to each other. The ternary complex structure of hAR•NADP+•WY 14,643 reveals the first structural evidence of a fibrate class drug binding to hAR. These observations demonstrate how fibrate molecules such as WY 14,643, besides being valued as agonists for PPAR, also inhibit hAR. PMID:27721416

Essential Requirements for Robust Signaling in Hfq Dependent Small RNA Networks

PubMed Central

Adamson, David N.; Lim, Han N.

2011-01-01

Bacteria possess networks of small RNAs (sRNAs) that are important for modulating gene expression. At the center of many of these sRNA networks is the Hfq protein. Hfq's role is to quickly match cognate sRNAs and target mRNAs from among a large number of possible combinations and anneal them to form duplexes. Here we show using a kinetic model that Hfq can efficiently and robustly achieve this difficult task by minimizing the sequestration of sRNAs and target mRNAs in Hfq complexes. This sequestration can be reduced by two non-mutually exclusive kinetic mechanisms. The first mechanism involves heterotropic cooperativity (where sRNA and target mRNA binding to Hfq is influenced by other RNAs bound to Hfq); this cooperativity can selectively decrease singly-bound Hfq complexes and ternary complexes with non-cognate sRNA-target mRNA pairs while increasing cognate ternary complexes. The second mechanism relies on frequent RNA dissociation enabling the rapid cycling of sRNAs and target mRNAs among different Hfq complexes; this increases the probability the cognate ternary complex forms before the sRNAs and target mRNAs degrade. We further demonstrate that the performance of sRNAs in isolation is not predictive of their performance within a network. These findings highlight the importance of experimentally characterizing duplex formation in physiologically relevant contexts with multiple RNAs competing for Hfq. The model will provide a valuable framework for guiding and interpreting these experiments. PMID:21876666

Chemical-Biological Properties of Zinc Sensors TSQ and Zinquin: Formation of Sensor-Zn-Protein Adducts versus Zn(Sensor)2 Complexes.

PubMed

Nowakowski, Andrew B; Meeusen, Jeffrey W; Menden, Heather; Tomasiewicz, Henry; Petering, David H

2015-12-21

Fluorescent zinc sensors are the most commonly used tool to study the intracellular mobile zinc status within cellular systems. Previously, we have shown that the quinoline-based sensors Zinquin and 6-methoxy-8-p-toluenesulfonamido-quinoline (TSQ) predominantly form ternary adducts with members of the Zn-proteome. Here, the chemistries of these sensors are further characterized, including how Zn(sensor)2 complexes may react in an intracellular environment. We demonstrate that these sensors are typically used in higher concentrations than needed to obtain maximum signal. Exposing cells to either Zn(Zinquin)2 or Zn(TSQ)2 resulted in efficient cellular uptake and the formation of sensor-Zn-protein adducts as evidenced by both a fluorescence spectral shift toward that of ternary adducts and the localization of the fluorescence signal within the proteome after gel filtration of cellular lysates. Likewise, reacting Zn(sensor)2 with the Zn-proteome from LLC-PK1 cells resulted in the formation of sensor-Zn-protein ternary adducts that could be inhibited by first saturating the Zn- proteome with excess sensor. Further, a native SDS-PAGE analysis of the Zn-proteome reacted with either the sensor or the Zn(sensor)2 complex revealed that both reactions result in the formation of a similar set of sensor-Zn-protein fluorescent products. The results of this experiment also demonstrated that TSQ and Zinquin react with different members of the Zn-proteome. Reactions with the model apo-Zn-protein bovine serum albumin showed that both Zn(TSQ)2 and Zn(Zinquin)2 reacted to form ternary adducts with its apo-Zn-binding site. Moreover, incubating Zn(sensor)2 complexes with non-zinc binding proteins failed to elicit a spectral shift in the fluorescence spectrum, supporting the premise that blue-shifted emission spectra are due to sensor-Zn-protein ternary adducts. It was concluded that Zn(sensors)2 species do not play a significant role in the overall reaction between these sensors and intact cells. In turn, this study further supports the formation of sensor-Zn-protein adducts as the principal observed fluorescent product during experiments employing these two sensors.

Crystallographic and spectroscopic snapshots reveal a dehydrogenase in action

DOE PAGES

Huo, Lu; Davis, Ian; Liu, Fange; ...

2015-01-07

Aldehydes are ubiquitous intermediates in metabolic pathways and their innate reactivity can often make them quite unstable. There are several aldehydic intermediates in the metabolic pathway for tryptophan degradation that can decay into neuroactive compounds that have been associated with numerous neurological diseases. An enzyme of this pathway, 2-aminomuconate-6-semialdehyde dehydrogenase, is responsible for ‘disarming’ the final aldehydic intermediate. Here we show the crystal structures of a bacterial analogue enzyme in five catalytically relevant forms: resting state, one binary and two ternary complexes, and a covalent, thioacyl intermediate. We also report the crystal structures of a tetrahedral, thiohemiacetal intermediate, a thioacylmore » intermediate and an NAD +-bound complex from an active site mutant. These covalent intermediates are characterized by single-crystal and solution-state electronic absorption spectroscopy. The crystal structures reveal that the substrate undergoes an E/Z isomerization at the enzyme active site before an sp 3-to-sp 2 transition during enzyme-mediated oxidation.« less

Stargazin regulates AMPA receptor trafficking through adaptor protein complexes during long-term depression

NASA Astrophysics Data System (ADS)

Matsuda, Shinji; Kakegawa, Wataru; Budisantoso, Timotheus; Nomura, Toshihiro; Kohda, Kazuhisa; Yuzaki, Michisuke

2013-11-01

Long-term depression (LTD) underlies learning and memory in various brain regions. Although postsynaptic AMPA receptor trafficking mediates LTD, its underlying molecular mechanisms remain largely unclear. Here we show that stargazin, a transmembrane AMPA receptor regulatory protein, forms a ternary complex with adaptor proteins AP-2 and AP-3A in hippocampal neurons, depending on its phosphorylation state. Inhibiting the stargazin-AP-2 interaction disrupts NMDA-induced AMPA receptor endocytosis, and inhibiting that of stargazin-AP-3A abrogates the late endosomal/lysosomal trafficking of AMPA receptors, thereby upregulating receptor recycling to the cell surface. Similarly, stargazin’s interaction with AP-2 or AP-3A is necessary for low-frequency stimulus-evoked LTD in CA1 hippocampal neurons. Thus, stargazin has a crucial role in NMDA-dependent LTD by regulating two trafficking pathways of AMPA receptors—transport from the cell surface to early endosomes and from early endosomes to late endosomes/lysosomes—through its sequential binding to AP-2 and AP-3A.

Atomic-scale properties of Ni-based FCC ternary, and quaternary alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamm, Artur; Aabloo, Alvo; Klintenberg, Mattias

2015-08-26

The aim of our study is to characterize some atomic-scale properties of Ni-based FCC multicomponent alloys. For this purpose, we use Monte Carlo method combined with density functional theory calculations to study short-range order (SRO), atomic displacements, electronic density of states, and magnetic moments in equimolar ternary NiCrCo, and quaternary NiCrCoFe alloys. The salient features for the ternary alloy are a negative SRO parameter between Ni Cr and a positive between Cr Cr pairs as well as a weakly magnetic state. For the quaternary alloy we predict negative SRO parameter for Ni Cr and Ni Fe pairs and positive formore » Cr Cr and Fe Fe pairs. Atomic displacements for both ternary and quaternary alloys are negligible. In contrast to the ternary, the quaternary alloy shows a complex magnetic structure. The electronic structure of the ternary and quaternary alloys shows differences near the Fermi energy between a random solid solution and the predicted structure with SRO. Despite that, the calculated EXAFS spectra does not show enough contrast to discriminate between random and ordered structures. Finally, the predicted SRO has an impact on point-defect energetics, electron phonon coupling and thermodynamic functions and thus, SRO should not be neglected when studying properties of these two alloys.« less

Retro-inverso d-peptide-modified hyaluronic acid/bioreducible hyperbranched poly(amido amine)/pDNA core-shell ternary nanoparticles for the dual-targeted delivery of short hairpin RNA-encoding plasmids.

PubMed

Gu, Jijin; Chen, Xinyi; Fang, Xiaoling; Sha, Xianyi

2017-07-15

The active targeting of gene carriers is a powerful strategy for improving tumour-specific delivery and therapy. Although numerous l-peptide ligands play significant roles in the active targeting of nanomedicine, retro-inverso d-peptides have been explored as targeting ligands due to their superior stability and bioactivity in vivo. In this study, retro-inverso d-peptide (RIF7)-modified hyaluronic acid (HA)/bioreducible hyperbranched poly(amido amine) (RHB)/plasmid DNA (pDNA) ternary nanoparticles were successfully developed using the layer-by-layer method for the CD44-positive tumour-specific delivery of short hairpin RNA (shRNA)-encoding pDNA through the combination of the Anxa1 (tumour vasculature) and CD44 (tumour cell-surface) receptors, which mediated the dual targeting. The potential of these newly designed nanoparticles was evaluated by examining the efficacy of their cellular uptake and transfection in cell monolayers, tumour spheroids, and malignant xenograft animal models. With negligible cytotoxicity, the spherical-shaped RIF7-HA/RHB/pDNA nanoparticles were the direct result of an electrostatic complex that had efficiently targeted CD44-positive tumour delivery, penetration, and cellular uptake in vitro. The nanoparticles showed excellent target-specific gene transfection even in the presence of serum. The in vivo therapeutic effect of RIF7-HA/RHB/pDNA-shRNA nanoparticle-mediated shRNA targeting of the Cyclin gene (shCyclin) was evaluated in tumour-bearing mice. The RIF7-HA/RHB/pDNA-shCyclin nanoparticles significantly increased the survival time of tumour-bearing mice and substantially reduced tumour growth due to their extremely specific tumour-targeting activity. These results suggested that the combination of HA and retro-inverso peptide RIF7 significantly increased the therapeutic effect of pDNA-shCyclin-loaded nanoparticles for CD44-positive tumours. Thus, RIF7-HA-mediated multi-target ternary gene vectors are an efficient and promising strategy for the delivery of pDNA-shRNA in the targeted treatment of malignant and metastatic cancers. Although l-peptide ligands play significant roles in the active targeting of nanomedicine, retro-inverso d-peptides have been explored as targeting ligands due to their superior stability and bioactivity in vivo. Retro-inverso peptide RIF7 was designed as a ligand of Anxa1 receptor. The resultant peptide, RIF7, displayed high binding efficiency within Anxa1 receptor, which is highly expressed tumour vasculature cells and some tumour cells such as B16F10 and U87MG cells. The most important feature of RIF7 is its high stability in the blood, which is suitable and promising for application in vivo. Multifunctional RIF7-HA was then synthesized by conjugating the RIF7 peptide to HA, which was used to modify the surface of RHB/pDNA nanoparticles to prepare RIF7-HA/RHB/pDNA core-shell ternary nanoparticles for the dual-targeted delivery of shRNA-encoding plasmids in vitro and in vivo. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Lipophilic ternary complexes in liquid-liquid extraction of trivalent lanthanides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumetta, Gregg J.; Levitskaia, Tatiana G.; Latesky, Stanley

2012-03-01

The formation of ternary complexes between lanthanide ions [Nd(III) or Eu(III)], octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO), and bis-(2-ethylhexyl)phosphoric acid (HDEHP) was probed by liquid-liquid extraction and spectroscopic techniques. Equilibrium modeling of data for the extraction of Nd(III) or Eu(III) from lactic acid media into n-dodecane solutions of CMPO and HDEHP indicates the predominant extracted species are of the type [Ln(AHA){sub 2}(A)] and [Ln(CMPO)(AHA){sub 2}(A)], where Ln = Nd or Eu and A represents the DEHP{sup -} anion. FTIR (for both Eu and Nd) and visible spectrophotometry (in the case of Nd) indicate the formation of the [Ln(CMPO)(A){sup 3}] complexes when CMPO ismore » added to n-dodecane solutions of the LnA{sub 3} compounds. Both techniques indicate a stronger propensity of CMPO to complex Nd(III) versus Eu(III).« less

Effector region of the translation elongation factor EF-Tu.GTP complex stabilizes an orthoester acid intermediate structure of aminoacyl-tRNA in a ternary complex.

PubMed Central

Förster, C; Limmer, S; Zeidler, W; Sprinzl, M

1994-01-01

tRNA(Val) from Escherichia coli was aminoacylated with [1-13C]valine and its complex with Thermus thermophilus elongation factor EF-Tu.GTP was analyzed by 13C NMR spectroscopy. The results suggest that the aminoacyl residue of the valyl-tRNA in ternary complex with bacterial EF-Tu and GTP is not attached to tRNA by a regular ester bond to either a 2'- or 3'-hydroxyl group; instead, an intermediate orthoester acid structure with covalent linkage to both vicinal hydroxyls of the terminal adenosine-76 is formed. Mutation of arginine-59 located in the effector region of EF-Tu, a conserved residue in protein elongation factors and the alpha subunits of heterotrimeric guanine nucleotide-binding regulatory proteins (G proteins), abolishes the stabilization of the orthoester acid structure of aminoacyl-tRNA. PMID:8183898

Characterization of WY 14,643 and its Complex with Aldose Reductase

DOE PAGES

Sawaya, Michael R.; Verma, Malkhey; Balendiran, Vaishnavi; ...

2016-10-10

The peroxisome proliferator, WY 14,643 exhibits a pure non-competitive inhibition pattern in the aldehyde reduction and in alcohol oxidation activities of human Aldose reductase (hAR). Fluorescence emission measurements of the equilibrium dissociation constants, Kd, of oxidized (hAR•NADP+) and reduced (hAR•NADPH) holoenzyme complexes display a 2-fold difference between them. Kd values for the dissociation of WY 14,643 from the oxidized (hAR•NADP+•WY 14,643) and reduced (hAR•NADPH•WY 14,643) ternary complexes are comparable to each other. The ternary complex structure of hAR•NADP+•WY 14,643 reveals the first structural evidence of a fibrate class drug binding to hAR. These observations demonstrate how fibrate molecules such asmore » WY 14,643, besides being valued as agonists for PPAR, also inhibit hAR.« less

Characterization of WY 14,643 and its Complex with Aldose Reductase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sawaya, Michael R.; Verma, Malkhey; Balendiran, Vaishnavi

The peroxisome proliferator, WY 14,643 exhibits a pure non-competitive inhibition pattern in the aldehyde reduction and in alcohol oxidation activities of human Aldose reductase (hAR). Fluorescence emission measurements of the equilibrium dissociation constants, Kd, of oxidized (hAR•NADP+) and reduced (hAR•NADPH) holoenzyme complexes display a 2-fold difference between them. Kd values for the dissociation of WY 14,643 from the oxidized (hAR•NADP+•WY 14,643) and reduced (hAR•NADPH•WY 14,643) ternary complexes are comparable to each other. The ternary complex structure of hAR•NADP+•WY 14,643 reveals the first structural evidence of a fibrate class drug binding to hAR. These observations demonstrate how fibrate molecules such asmore » WY 14,643, besides being valued as agonists for PPAR, also inhibit hAR.« less

Interactions between the cyclic AMP receptor protein and the alpha subunit of RNA polymerase at the Escherichia coli galactose operon P1 promoter.

PubMed

Attey, A; Belyaeva, T; Savery, N; Hoggett, J; Fujita, N; Ishihama, A; Busby, S

1994-10-25

DNAase I footprinting has been used to study open complexes between Escherichia coli RNA polymerase and the galactose operon P1 promoter, both in the absence and the presence of CRP (the cyclic AMP receptor protein, a transcription activator). From the effects of deletion of the C-terminal part of the RNA polymerase alpha subunit, we deduce that alpha binds at the upstream end of both the binary RNA polymerase-galP1 and ternary RNA polymerase-CRP-galP1 complexes. Disruption of the alpha-upstream contact suppresses open complex formation at galP1 at lower temperatures. In ternary RNA polymerase-CRP-galP1 complexes, alpha appears to make direct contact with Activating Region 1 in CRP. DNAase I footprinting has been used to detect and quantify interactions between purified alpha and CRP bound at galP1.

Interactions between the cyclic AMP receptor protein and the alpha subunit of RNA polymerase at the Escherichia coli galactose operon P1 promoter.

PubMed Central

Attey, A; Belyaeva, T; Savery, N; Hoggett, J; Fujita, N; Ishihama, A; Busby, S

1994-01-01

DNAase I footprinting has been used to study open complexes between Escherichia coli RNA polymerase and the galactose operon P1 promoter, both in the absence and the presence of CRP (the cyclic AMP receptor protein, a transcription activator). From the effects of deletion of the C-terminal part of the RNA polymerase alpha subunit, we deduce that alpha binds at the upstream end of both the binary RNA polymerase-galP1 and ternary RNA polymerase-CRP-galP1 complexes. Disruption of the alpha-upstream contact suppresses open complex formation at galP1 at lower temperatures. In ternary RNA polymerase-CRP-galP1 complexes, alpha appears to make direct contact with Activating Region 1 in CRP. DNAase I footprinting has been used to detect and quantify interactions between purified alpha and CRP bound at galP1. Images PMID:7971267

Spectral and theoretical study on complexation of sulfamethoxazole with β- and HPβ-cyclodextrins in binary and ternary systems

NASA Astrophysics Data System (ADS)

Varghese, Beena; Suliman, FakhrEldin O.; Al-Hajri, Aalia; Al Bishri, Nahed Surur S.; Al-Rwashda, Nathir

2018-02-01

The inclusion complexes of sulfamethoxazole (SMX) with β-cyclodextrin (βCD) and (2-hydroxypropyl) β-cyclodextrin (HPβCD) were prepared. Fluorescence spectroscopy and electrospray mass spectrometry, ESI-MS, were used to investigate and characterize the inclusion complexation of SMX with cyclodextrins in solutions. Whereas in the solid state the complexes were characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD) and Raman techniques. Enhanced twisted intramolecular charge transfer (TICT), emission as well as local excited (LE) bands were observed upon addition of HPβCD indicate that SMX enters deeper into the cyclodextrins cavity. The stoichiometries and association constants of these complexes have been determined by monitoring the fluorescence data. The effect of presence of ternary components like arginine and cysteine on the complexation efficiency of SMX with cyclodextrins was investigated. Molecular Dynamic simulations were also performed to shed an atomistic insight into the complexation mechanism. The results obtained showed that complexes of SMX with both cyclodextrins are stabilized in aqueous media by strong hydrogen bonding interactions.

Coiled-coil coactivators play a structural role mediating interactions in hypoxia-inducible factor heterodimerization

DOE PAGES

Guo, Yirui; Scheuermann, Thomas H.; Partch, Carrie L.; ...

2015-01-27

The hypoxia-inducible factor complex (HIF-α·aryl hydrocarbon receptor nuclear translocator (ARNT)) requires association with several transcription coactivators for a successful cellular response to hypoxic stress. In addition to the conventional global transcription coactivator CREB-binding protein/p300 (CBP/p300) that binds to the HIF-α transactivation domain, a new group of transcription coactivators called the coiled-coil coactivators (CCCs) interact directly with the second PER-ARNT-SIM (PAS) domain of ARNT (ARNT PAS-B). These less studied transcription coactivators play essential roles in the HIF-dependent hypoxia response, and CCC misregulation is associated with several forms of cancer. To better understand CCC protein recruitment by the heterodimeric HIF transcription factor,more » we used x-ray crystallography, NMR spectroscopy, and biochemical methods to investigate the structure of the ARNT PAS-B domain in complex with the C-terminal fragment of a coiled-coil coactivator protein, transforming acidic coiled-coil coactivator 3 (TACC3). We found that the HIF-2α PAS-B domain also directly interacts with TACC3, motivating an NMR data-derived model suggesting a means by which TACC3 could form a ternary complex with HIF-2α PAS-B and ARNT PAS-B via β-sheet/coiled-coil interactions. Furthermore, these findings suggest that TACC3 could be recruited as a bridge to cooperatively mediate between the HIF-2α PAS-B·ARNT PAS-B complex, thereby participating more directly in HIF-dependent gene transcription than previously anticipated.« less

Structure and reactivity of ferrihydrite-soil organic carbon-calcium ternary complexes

NASA Astrophysics Data System (ADS)

Yang, Y.; Adhikari, D.; Sowers, T.; Stuckey, J.; Poulson, S.; Sparks, D. L.

2017-12-01

Complete understanding about the interactions between soil organic carbon (SOC) and minerals is important for predicting the stability of SOC and its response to climate change. Recent studies have shown the importance of calcium (Ca)-bearing minerals and iron (Fe) oxide in associating with and stabilizing SOC. In this study, we have investigated the formation and reactivity of ferrihydrite-SOC-Ca ternary complexes. During the co-precipitation of ferrihydrite with SOC in the presence of Ca2+, 60% of SOC can be co-precipitated with ferrihydrite at a C/Fe (molar ratio) of up to 10, whereas the Ca/Fe ratio was saturated at 0.2. Increasing amount of Ca2+ did not affect the co-precipitation of SOC with ferrihydrite or the lability of ferrihydrite-bound SOC. In addition, microbial reduction of ferrihydrite and reductive release of ferrihydrite-bound SOC were not influenced by the presence of Ca, but the pathway for Fe mineral transformation during the reduction was affected by Ca. In the meantime, Fe reduction selectively released carboxylic-enriched SOC. As a comparison, the presence of SOC increased the incorporation of Ca into the structure of ferrihydrite. Our results indicate the formation of ferrihydrite-SOC-Ca complexes, with organic carbon bridging the ferrihydrite and Ca. Such ternary complexes potentially play an important role in regulating the interactions between SOC and mineral phases in soil.

Antimicrobial and SOD activities of novel transition metal ternary complexes of iminodiacetic acid containing alpha-diimine as auxiliary ligand.

PubMed

Siddiqi, Zafar A; Shahid, M; Khalid, Mohd; Kumar, S

2009-06-01

Ternary complexes containing an alpha-diimine auxiliary ligand have been widely used as models for several mono and polynuclear metal enzymes. The present ternary complexes [M(IDA)(Phen)H(2)O] x xH(2)O (x = 2, 3 or 4) were prepared as novel antimicrobial agents employing reactions of Cu(OAc)(2) or MCl(2) (M = Co, Ni, Cr) with iminodiacetic acid (H(2)IDA) in the presence of 1,10-phenanthroline (Phen), whose chemical structure and bonding were elucidated by IR, FAB-Mass, (1)H, (13)C NMR, EPR spectral and elemental analyses. The antimicrobial activities against Escherichia coli (K-12), Bacillus subtilis (MTCC 121), Staphylococcus aureus (IOA-SA-22), Salmonella typhimurium (MTCC 98), Candida albicans, Aspergillus fumigatus and Penicillium marneffei (isolates from Department of Microbiology, Faculty of Agricultural Science, AMU) were investigated and significant activities were obtained. The superoxide dismutase activity of the Cu(II) complex was assessed by NBT assay. The single crystal X-ray structure for [Cu(IDA)(Phen)H(2)O] x 2 H(2)O indicates a triclinic unit cell in P-1 space group with structural parameters, a = 6.745(5), b = 10.551(5), c = 11.414(5)A, alpha = 95.770(5), beta = 91.396(5), gamma = 92.518(5) degrees and presence of an extensive H-bonding and pi-pi stacking interactions which generate a supramolecular framework.

Hippocampal A-type current and Kv4.2 channel modulation by the sulfonylurea compound NS5806.

PubMed

Witzel, Katrin; Fischer, Paul; Bähring, Robert

2012-12-01

We examined the effects of the sulfonylurea compound NS5806 on neuronal A-type channel function. Using whole-cell patch-clamp we studied the effects of NS5806 on the somatodendritic A-type current (I(SA)) in cultured hippocampal neurons and the currents mediated by Kv4.2 channels coexpressed with different auxiliary β-subunits, including both Kv channel interacting proteins (KChIPs) and dipeptidyl aminopeptidase-related proteins (DPPs), in HEK 293 cells. The amplitude of the I(SA) component in hippocampal neurons was reduced in the presence of 20 μM NS5806. I(SA) decay kinetics were slowed and the recovery kinetics accelerated, but the voltage dependence of steady-state inactivation was shifted to more negative potentials by NS5806. The peak amplitudes of currents mediated by ternary Kv4.2 channel complexes, associated with DPP6-S (short splice-variant) and either KChIP2, KChIP3 or KChIP4, were potentiated and their macroscopic inactivation slowed by NS5806, whereas the currents mediated by binary Kv4.2 channels, associated only with DPP6-S, were suppressed, and the NS5806-mediated slowing of macroscopic inactivation was less pronounced. Neither potentiation nor suppression and no effect on current decay kinetics in the presence of NS5806 were observed for Kv4.2 channels associated with KChIP3 and the N-type inactivation-conferring DPP6a splice-variant. For all recombinant channel complexes, NS5806 slowed the recovery from inactivation and shifted the voltage dependence of steady-state inactivation to more negative potentials. Our results demonstrate the activity of NS5806 on native I(SA) and possible molecular correlates in the form of recombinant Kv4.2 channels complexed with different KChIPs and DPPs, and they shed some light on the mechanism of NS5806 action. Copyright © 2012 Elsevier Ltd. All rights reserved.

Investigation of Cyclodextrin-Based Nanosponges for Solubility and Bioavailability Enhancement of Rilpivirine.

PubMed

Rao, Monica R P; Chaudhari, Jagruti; Trotta, Francesco; Caldera, Fabrizio

2018-06-04

Rilpivrine is BCS class II drug used for treatment of HIV infection. The drug has low aqueous solubility (0.0166 mg/ml) and dissolution rate leading to low bioavailability (32%). Aim of this work was to enhance solubility and dissolution of rilpivirine using beta-cyclodextrin-based nanosponges. These nanosponges are biocompatible nanoporous particles having high loading capacity to form supramolecular inclusion and non-inclusion complexes with hydrophilic and lipophilic drugs for solubility enhancement. Beta-cyclodextrin was crosslinked with carbonyl diimidazole and pyromellitic dianhydride to prepare nanosponges. The nanosponges were loaded with rilpivirine by solvent evaporation method. Binary and ternary complexes of drug with β-CD, HP-β-CD, nanosponges, and tocopherol polyethylene glycol succinate were prepared and characterized by phase solubility, saturation solubility in different media, in vitro dissolution, and in vivo pharmacokinetics. Spectral analysis by Fourier transform infrared spectroscopy, powder X-ray diffraction, and differential scanning calorimetry was performed. Results obtained from spectral characterization confirmed inclusion complexation. Phase solubility studies indicated stable complex formation. Saturation solubility was found to be 10-13-folds higher with ternary complexes in distilled water and 12-14-fold higher in 0.1 N HCl. Solubility enhancement was evident in biorelevant media. Molecular modeling studies revealed possible mode of entrapment of rilpivirine within β-CD cavities. A 3-fold increase in dissolution with ternary complexes was observed. Animal studies revealed nearly 2-fold increase in oral bioavailability of rilpivirine. It was inferred that electronic interactions, hydrogen bonding, and van der Waals forces are involved in the supramolecular interactions.

Nitric oxide donors or nitrite counteract copper-[dithiocarbamate](2)-mediated tumor cell death and inducible nitric oxide synthase down-regulation: possible role of a nitrosyl-copper [dithiocarbamate](2) complex.

PubMed

Rhenals, Maricela Viola; Strasberg-Rieber, Mary; Rieber, Manuel

2010-02-25

In contrast to other metal-dithiocarbamate [DEDTC] complexes, the copper-DEDTC complex is highly cytotoxic, inducing oxidative stress, preferentially in tumor cells. Because nitric oxide (NO) forms adducts with Cu[DEDTC](2), we investigated whether NO donors like S-nitroso-N-acetyl penicillamine (SNAP) or sodium nitroprusside (SNP), and nitrite, a NO decomposition product, modulate Cu[DEDTC](2) cytotoxicity against human tumor cells. We show that apoptosis-associated PARP cleavage and inducible nitric oxide synthase (iNOS) down-regulation induced by nanomolar Cu[DEDTC](2), are counteracted by 50 muM SNAP, SNP, or CoCl(2), an inducer of hypoxia and NO signaling. Nitrite was stochiometrically effective in antagonizing Cu[DEDTC](2) cytotoxicity and inducing shifts in the absorption spectrum of the binary complex in the 280 and 450 nm regions. Subtoxic concentrations of Cu[DEDTC](2) became lethal when tumor cells were pretreated with c-PTIO, a membrane-impermeable scavenger for extracellular NO. Our results suggest that: (a) reactive oxygen species induced by Cu[DEDTC](2) are scavenged by nitrite released from NO, (b) the extent of lethality of Cu[DEDTC](2) is dependent on the reciprocal formation of an inactive ternary Cu[DEDTC](2)NO copper-nitrosyl complex.

Ternary copper(II) complex: NCI60 screening, toxicity studies, and evaluation of efficacy in xenograft models of nasopharyngeal carcinoma.

PubMed

Ahmad, Munirah; Suhaimi, Shazlan-Noor; Chu, Tai-Lin; Abdul Aziz, Norazlin; Mohd Kornain, Noor-Kaslina; Samiulla, D S; Lo, Kwok-Wai; Ng, Chew-Hee; Khoo, Alan Soo-Beng

2018-01-01

Copper(II) ternary complex, [Cu(phen)(C-dmg)(H2O)]NO3 was evaluated against a panel of cell lines, tested for in vivo efficacy in nasopharyngeal carcinoma xenograft models as well as for toxicity in NOD scid gamma mice. The Cu(II) complex displayed broad spectrum cytotoxicity against multiple cancer types, including lung, colon, central nervous system, melanoma, ovarian, and prostate cancer cell lines in the NCI-60 panel. The Cu(II) complex did not cause significant induction of cytochrome P450 (CYP) 3A and 1A enzymes but moderately inhibited CYP isoforms 1A2, 2C9, 2C19, 2D6, 2B6, 2C8 and 3A4. The complex significantly inhibited tumor growth in nasopharyngeal carcinoma xenograft bearing mice models at doses which were well tolerated without causing significant or permanent toxic side effects. However, higher doses which resulted in better inhibition of tumor growth also resulted in toxicity.

A novel method based on selective laser sintering for preparing high-performance carbon fibres/polyamide12/epoxy ternary composites

NASA Astrophysics Data System (ADS)

Zhu, Wei; Yan, Chunze; Shi, Yunsong; Wen, Shifeng; Liu, Jie; Wei, Qingsong; Shi, Yusheng

2016-09-01

A novel method based on selective laser sintering (SLS) process is proposed for the first time to prepare complex and high-performance carbon fibres/polyamide12/epoxy (CF/PA12/EP) ternary composites. The procedures are briefly described as follows: prepare polyamide12 (PA12) coated carbon fibre (CF) composite powder; build porous green parts by SLS; infiltrate the green parts with high-performance thermosetting epoxy (EP) resin; and finally cure the resin at high temperature. The obtained composites are a ternary composite system consisting of the matrix of novolac EP resin, the reinforcement of CFs and the transition thin layer of PA12 with a thickness of 595 nm. The SEM images and micro-CT analysis prove that the ternary system is a three-dimensional co-continuous structure and the reinforcement of CFs are well dispersed in the matrix of EP with the volume fraction of 31%. Mechanical tests show that the composites fabricated by this method yield an ultimate tensile strength of 101.03 MPa and a flexural strength of 153.43 MPa, which are higher than those of most of the previously reported SLS materials. Therefore, the process proposed in this paper shows great potential for manufacturing complex, lightweight and high-performance CF reinforced composite components in aerospace, automotive industries and other areas.

A novel method based on selective laser sintering for preparing high-performance carbon fibres/polyamide12/epoxy ternary composites

PubMed Central

Zhu, Wei; Yan, Chunze; Shi, Yunsong; Wen, Shifeng; Liu, Jie; Wei, Qingsong; Shi, Yusheng

2016-01-01

A novel method based on selective laser sintering (SLS) process is proposed for the first time to prepare complex and high-performance carbon fibres/polyamide12/epoxy (CF/PA12/EP) ternary composites. The procedures are briefly described as follows: prepare polyamide12 (PA12) coated carbon fibre (CF) composite powder; build porous green parts by SLS; infiltrate the green parts with high-performance thermosetting epoxy (EP) resin; and finally cure the resin at high temperature. The obtained composites are a ternary composite system consisting of the matrix of novolac EP resin, the reinforcement of CFs and the transition thin layer of PA12 with a thickness of 595 nm. The SEM images and micro-CT analysis prove that the ternary system is a three-dimensional co-continuous structure and the reinforcement of CFs are well dispersed in the matrix of EP with the volume fraction of 31%. Mechanical tests show that the composites fabricated by this method yield an ultimate tensile strength of 101.03 MPa and a flexural strength of 153.43 MPa, which are higher than those of most of the previously reported SLS materials. Therefore, the process proposed in this paper shows great potential for manufacturing complex, lightweight and high-performance CF reinforced composite components in aerospace, automotive industries and other areas. PMID:27650254

The reaction mechanism of methyl-coenzyme M reductase: How an enzyme enforces strict binding order

DOE PAGES

Wongnate, Thanyaporn; Ragsdale, Stephen W.

2015-02-17

Methyl-coenzyme M reductase (MCR) is a nickel tetrahydrocorphinoid (coenzyme F430) containing enzyme involved in the biological synthesis and anaerobic oxidation of methane. MCR catalyzes the conversion of methyl-2-mercaptoethanesulfonate (methyl-SCoM) and N-7-mercaptoheptanoylthreonine phosphate (CoB 7SH) to CH 4 and the mixed disulfide CoBS-SCoM. In this study, the reaction of MCR from Methanothermobacter marburgensis, with its native substrates was investigated using static binding, chemical quench, and stopped-flow techniques. Rate constants were measured for each step in this strictly ordered ternary complex catalytic mechanism. Surprisingly, in the absence of the other substrate, MCR can bind either substrate; however, only one binary complex (MCR·methyl-SCoM)more » is productive whereas the other (MCR·CoB 7SH) is inhibitory. Moreover, the kinetic data demonstrate that binding of methyl-SCoM to the inhibitory MCR·CoB 7SH complex is highly disfavored ( Kd = 56 mM). However, binding of CoB 7SH to the productive MCR·methyl-SCoM complex to form the active ternary complex (CoB 7SH·MCR(Ni I)·CH 3SCoM) is highly favored ( Kd = 79 μM). Only then can the chemical reaction occur ( kobs = 20 s -1 at 25 °C), leading to rapid formation and dissociation of CH 4 leaving the binary product complex (MCR(Ni II)·CoB 7S -·SCoM), which undergoes electron transfer to regenerate Ni(I) and the final product CoBS-SCoM. In conclusion, this first rapid kinetics study of MCR with its natural substrates describes how an enzyme can enforce a strictly ordered ternary complex mechanism and serves as a template for identification of the reaction intermediates.« less

Ternary cyclodextrin polyurethanes containing phosphate groups: Synthesis and complexation of ciprofloxacin.

PubMed

Moreira, Mirna Pereira; Andrade, George Ricardo Santana; de Araujo, Marcia Valeria Gaspar; Kubota, Tatiana; Gimenez, Iara F

2016-10-20

Synthesis of ternary polyurethanes (PUs) from hexamethylenediisocyanate, β-cyclodextrin and β-glycerophosphate (acid and calcium salt) was studies varying synthesis parameters such as monomer proportion, heating method (reflux and microwave), and catalyst amount. Favorable conditions were provided by microwave irradiation and use of β-glycerophosphoric acid although the results suggest that it is possible to obtain ternary PUs with the calcium salt. FTIR data indicated the existence of secondary urea linkages. After characterization of ternary PUs by FTIR spectroscopy, XRD and thermal analysis, as well as evidences that the cyclodextrin cavities remained active toward inclusion of guest molecules, the possibility of inclusion of the antibiotic ciprofloxacin was evaluated. Absence of ciprofloxacin melting peak in DSC curves indicated that it is molecularly dispersed within the polymer, possibly included in the cyclodextrin. In vitro release experiments suggested additional non-inclusion interactions, showing also that the use of dialysis membranes may mask the actual release profile. Copyright © 2016. Published by Elsevier Ltd.

Ternary complex factor SAP-1 is required for Erk-mediated thymocyte positive selection.

PubMed

Costello, Patrick S; Nicolas, Robert H; Watanabe, Yasuyuki; Rosewell, Ian; Treisman, Richard

2004-03-01

Thymocyte selection and differentiation requires extracellular signal-regulated kinase (Erk) signaling, but transcription factor substrates of Erk in thymocytes are unknown. We have characterized the function of SAP-1 (Elk4), an Erk-regulated transcription factor, in thymocyte development. Early thymocyte development was normal, but single-positive thymocyte and peripheral T cell numbers were reduced, reflecting a T cell-autonomous defect. T cell receptor-induced activation of SAP-1 target genes such as Egr1 was substantially impaired in double-positive thymocytes, although Erk activation was normal. Analysis of T cell receptor transgenes showed that positive selection was reduced by 80-90% in SAP-1-deficient mice; heterozygous mice showed a moderate defect. Negative selection was unimpaired. SAP-1 thus directly links Erk signaling to the transcriptional events required for thymocyte positive selection.

FBI-1 functions as a novel AR co-repressor in prostate cancer cells.

PubMed

Cui, Jiajun; Yang, Yutao; Zhang, Chuanfu; Hu, Pinliang; Kan, Wei; Bai, Xianhong; Liu, Xuelin; Song, Hongbin

2011-03-01

The pro-oncogene FBI-1, encoded by Zbtb7a, is a transcriptional repressor that belongs to the POK (POZ/BTB and Krüppel) protein family. In this study, we investigated a potential interaction between androgen receptor (AR) signaling and FBI-1 and demonstrated that overexpression of FBI-1 inhibited ligand-dependent AR activation. A protein-protein interaction was identified between FBI-1 and AR in a ligand-dependent manner. Furthermore, FBI-1, AR and SMRT formed a ternary complex and FBI-1 enhanced the recruitment of NCoR and SMRT to endogenous PSA upstream sequences. Our data also indicated that the FBI-1-mediated inhibition of AR transcriptional activity is partially dependent on HDAC. Interestingly, FBI-1 plays distinct roles in regulating LNCaP (androgen-dependent) and PC-3 cell (androgen-independent) proliferation.

Effects of adding corn oil and soy protein to corn starch on the physicochemical and digestive properties of the starch.

PubMed

Chen, Xu; He, Xiao-Wei; Zhang, Bin; Fu, Xiong; Jane, Jay-Lin; Huang, Qiang

2017-11-01

This study aimed to understand effects of adding corn oil (CO) and soy protein (SP) to corn starch on the physicochemical properties and digestive rates of annealed starch complex and mechanisms of interactions between corn starch (CS), CO and SP. Binary and ternary blends were prepared using CS mixed with CO (10%, dsb) and/or SP (10%, dsb) and incubated in a water bath at 50°C for 14h. Results showed that more agglomerates of the granules were in the ternary blends. With the addition of CO and/or SP, the CS displayed a decreased pasting temperature, an increased peak viscosity and a decreased enthalpy change of amylose-lipid complex dissociation. The CO can reinforce but SP hinder the annealing phenomenon. Results also showed that CO decreased retrogradation of CS, whereas SP increased it. The digestibility studies showed that the addition of CO and SP decreased the content of rapidly digestible starch and increased the sum of slowly digestible starch and resistant starch contents. SP displayed more impact on the digestibility of the ternary blends than CO. The physical barrier of CO, and amylose-lipid complex and protein-starch matrix can provide resistance to starch digestion. Copyright © 2017. Published by Elsevier B.V.

Experimental and theoretical insight into the cooperativity effect in composite wax powder and ternary complex of coronene with CH4 and Mn+ (Mn+ = Li+, Na+, K+, Be2+, Mg2+ or Ca2+)

NASA Astrophysics Data System (ADS)

Jiang, Le-tao; Bai, Pei-kang; Wang, Jian-hong; Liu, Bin; Li, Yu-xin

2018-01-01

The experimental infrared (IR) spectrum of composite wax powder was investigated. The frequency shifts of the C=C anti-symmetrical stretching mode were observed and the experimental cooperativity effect involving Na+...π interaction was suggested. In order to further reveal the nature of cooperativity effect, the interaction energies in Mn+...coronene...CH4 (Mn+ = Li+, Na+, K+, Be2+, Mg2+ or Ca2+) as the model systems of composite wax powder were calculated by using the B3LYP, M06-2X and MP2 methods with 6-311++G** basis set. The results show that the Mn+...π interactions were strengthened upon the formation of ternary complexes. Although the changes of absolute values of the interactions between CH4 and coronene were not obvious, the relative values were considerably significant upon the formation of ternary complexes. The cooperativity effect was perhaps the reason for the formation of notable advantage of composite wax powder upon the introduction of surfactant with cation into wax powder. Reduced density gradient and atoms-in-molecules analysis confirm the cooperativity effect in Mn+...coronene...CH4, and reveal the nature of the formation of the predominant advantage of composite wax powder.

Solubility enhancement of miconazole nitrate: binary and ternary mixture approach.

PubMed

Rai, Vineet Kumar; Dwivedi, Harinath; Yadav, Narayan Prasad; Chanotiya, Chandan Singh; Saraf, Shubhini A

2014-08-01

Enhancement of aqueous solubility of very slightly soluble Miconazole Nitrate (MN) is required to widen its application from topical formulation to oral/mucoadhesive formulations. Aim of the present investigation was to enhance the aqueous solubility of MN using binary and ternary mixture approach. Binary mixtures such as solvent deposition, inclusion complexation and solid dispersion were adopted to enhance solubility using different polymers like lactose, beta-cyclodextrin (β-CD) and polyethylene-glycol 6000 (PEG 6000), respectively. Batches of binary mixtures with highest solubility enhancement potentials were further mixed to form ternary mixture by a simple kneading method. Drug polymer interaction and mixture morphology was studied using the Fourier transform infrared spectroscopy and the scanning electron microscopy, respectively along with their saturation solubility studies and drug release. An excellent solubility enhancement, i.e. up to 72 folds and 316 folds of MN was seen by binary and ternary mixture, respectively. Up to 99.5% drug was released in 2 h from the mixtures of MN and polymers. RESULTS revealed that solubility enhancement by binary mixtures is achieved due to surface modification and by increasing wettability of MN. Tremendous increase in solubility of MN by ternary mixture could possibly be due to blending of water soluble polymers, i.e. lactose and PEG 6000 with β-CD which was found to enhance the solubilizing nature of β-CD. Owing to the excellent solubility enhancement potential of ternary mixtures in enhancing MN solubility from 110.4 μg/ml to 57640.0 μg/ml, ternary mixture approach could prove to be promising in the development of oral/mucoadhesive formulations.

How a low-fidelity DNA polymerase chooses non-Watson-Crick from Watson-Crick incorporation.

PubMed

Wu, Wen-Jin; Su, Mei-I; Wu, Jian-Li; Kumar, Sandeep; Lim, Liang-Hin; Wang, Chun-Wei Eric; Nelissen, Frank H T; Chen, Ming-Chuan Chad; Doreleijers, Jurgen F; Wijmenga, Sybren S; Tsai, Ming-Daw

2014-04-02

A dogma for DNA polymerase catalysis is that the enzyme binds DNA first, followed by MgdNTP. This mechanism contributes to the selection of correct dNTP by Watson-Crick base pairing, but it cannot explain how low-fidelity DNA polymerases overcome Watson-Crick base pairing to catalyze non-Watson-Crick dNTP incorporation. DNA polymerase X from the deadly African swine fever virus (Pol X) is a half-sized repair polymerase that catalyzes efficient dG:dGTP incorporation in addition to correct repair. Here we report the use of solution structures of Pol X in the free, binary (Pol X:MgdGTP), and ternary (Pol X:DNA:MgdGTP with dG:dGTP non-Watson-Crick pairing) forms, along with functional analyses, to show that Pol X uses multiple unprecedented strategies to achieve the mutagenic dG:dGTP incorporation. Unlike high fidelity polymerases, Pol X can prebind purine MgdNTP tightly and undergo a specific conformational change in the absence of DNA. The prebound MgdGTP assumes an unusual syn conformation stabilized by partial ring stacking with His115. Upon binding of a gapped DNA, also with a unique mechanism involving primarily helix αE, the prebound syn-dGTP forms a Hoogsteen base pair with the template anti-dG. Interestingly, while Pol X prebinds MgdCTP weakly, the correct dG:dCTP ternary complex is readily formed in the presence of DNA. H115A mutation disrupted MgdGTP binding and dG:dGTP ternary complex formation but not dG:dCTP ternary complex formation. The results demonstrate the first solution structural view of DNA polymerase catalysis, a unique DNA binding mode, and a novel mechanism for non-Watson-Crick incorporation by a low-fidelity DNA polymerase.

X-ray structure of the ternary MTX·NADPH complex of the anthrax dihydrofolate reductase: A pharmacophore for dual-site inhibitor design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennett, Brad C.; Wan, Qun; Ahmad, Md Faiz

2009-11-18

For reasons of bioterrorism and drug resistance, it is imperative to identify and develop new molecular points of intervention against anthrax. Dihydrofolate reductase (DHFR) is a highly conserved enzyme and an established target in a number of species for a variety of chemotherapeutic programs. Recently, the crystal structure of B. anthracis DHFR (baDHFR) in complex with methotrexate (MTX) was determined and, based on the structure, proposals were made for drug design strategies directed against the substrate binding site. However, little is gleaned about the binding site for NADPH, the cofactor responsible for hydride transfer in the catalytic mechanism. In themore » present study, X-ray crystallography at 100 K was used to determine the structure of baDHFR in complex with MTX and NADPH. Although the NADPH binding mode is nearly identical to that seen in other DHFR ternary complex structures, the adenine moiety adopts an off-plane tilt of nearly 90 deg. and this orientation is stabilized by hydrogen bonds to functionally conserved Arg residues. A comparison of the binding site, focusing on this region, between baDHFR and the human enzyme is discussed, with an aim at designing species-selective therapeutics. Indeed, the ternary model, refined to 2.3{angstrom} resolution, provides an accurate template for testing the feasibility of identifying dual-site inhibitors, compounds that target both the substrate and cofactor binding site. With the ternary model in hand, using in silico methods, several compounds were identified which could potentially form key bonding contacts in the substrate and cofactor binding sites. Ultimately, two structurally distinct compounds were verified that inhibit baDHFR at low {mu}M concentrations. The apparent K{sub d} for one of these, (2-(3-(2-(hydroxyimino)-2-(pyridine-4-yl)-6,7-dimethylquinoxalin-2-yl)-1-(pyridine-4-yl)ethanone oxime), was measured by fluorescence spectroscopy to be 5.3 {mu}M.« less

Fibroblast Growth Factor-based Signaling through Synthetic Heparan Sulfate Blocks Copolymers Studied Using High Cell Density Three-dimensional Cell Printing*

PubMed Central

Sterner, Eric; Masuko, Sayaka; Li, Guoyun; Li, Lingyun; Green, Dixy E.; Otto, Nigel J.; Xu, Yongmei; DeAngelis, Paul L.; Liu, Jian; Dordick, Jonathan S.; Linhardt, Robert J.

2014-01-01

Four well-defined heparan sulfate (HS) block copolymers containing S-domains (high sulfo group content) placed adjacent to N-domains (low sulfo group content) were chemoenzymatically synthesized and characterized. The domain lengths in these HS block co-polymers were ∼40 saccharide units. Microtiter 96-well and three-dimensional cell-based microarray assays utilizing murine immortalized bone marrow (BaF3) cells were developed to evaluate the activity of these HS block co-polymers. Each recombinant BaF3 cell line expresses only a single type of fibroblast growth factor receptor (FGFR) but produces neither HS nor fibroblast growth factors (FGFs). In the presence of different FGFs, BaF3 cell proliferation showed clear differences for the four HS block co-polymers examined. These data were used to examine the two proposed signaling models, the symmetric FGF2-HS2-FGFR2 ternary complex model and the asymmetric FGF2-HS1-FGFR2 ternary complex model. In the symmetric FGF2-HS2-FGFR2 model, two acidic HS chains bind in a basic canyon located on the top face of the FGF2-FGFR2 protein complex. In this model the S-domains at the non-reducing ends of the two HS proteoglycan chains are proposed to interact with the FGF2-FGFR2 protein complex. In contrast, in the asymmetric FGF2-HS1-FGFR2 model, a single HS chain interacts with the FGF2-FGFR2 protein complex through a single S-domain that can be located at any position within an HS chain. Our data comparing a series of synthetically prepared HS block copolymers support a preference for the symmetric FGF2-HS2-FGFR2 ternary complex model. PMID:24563485

In vitro selection of DNA elements highly responsive to the human T-cell lymphotropic virus type I transcriptional activator, Tax.

PubMed

Paca-Uccaralertkun, S; Zhao, L J; Adya, N; Cross, J V; Cullen, B R; Boros, I M; Giam, C Z

1994-01-01

The human T-cell lymphotropic virus type I (HTLV-I) transactivator, Tax, the ubiquitous transcriptional factor cyclic AMP (cAMP) response element-binding protein (CREB protein), and the 21-bp repeats in the HTLV-I transcriptional enhancer form a ternary nucleoprotein complex (L. J. Zhao and C. Z. Giam, Proc. Natl. Acad. Sci. USA 89:7070-7074, 1992). Using an antibody directed against the COOH-terminal region of Tax along with purified Tax and CREB proteins, we selected DNA elements bound specifically by the Tax-CREB complex in vitro. Two distinct but related groups of sequences containing the cAMP response element (CRE) flanked by long runs of G and C residues in the 5' and 3' regions, respectively, were preferentially recognized by Tax-CREB. In contrast, CREB alone binds only to CRE motifs (GNTGACG[T/C]) without neighboring G- or C-rich sequences. The Tax-CREB-selected sequences bear a striking resemblance to the 5' or 3' two-thirds of the HTLV-I 21-bp repeats and are highly inducible by Tax. Gel electrophoretic mobility shift assays, DNA transfection, and DNase I footprinting analyses indicated that the G- and C-rich sequences flanking the CRE motif are crucial for Tax-CREB-DNA ternary complex assembly and Tax transactivation but are not in direct contact with the Tax-CREB complex. These data show that Tax recruits CREB to form a multiprotein complex that specifically recognizes the viral 21-bp repeats. The expanded DNA binding specificity of Tax-CREB and the obligatory role the ternary Tax-CREB-DNA complex plays in transactivation reveal a novel mechanism for regulating the transcriptional activity of leucine zipper proteins like CREB.

Thermodynamic studies of drug-alpha-cyclodextrin interactions in water at 298.15 K: promazine hydrochloride/chlorpromazine hydrochloride + alpha-cyclodextrin + H(2)O systems.

PubMed

Terdale, Santosh S; Dagade, Dilip H; Patil, Kesharsingh J

2007-12-06

Data on osmotic coefficients have been obtained for a binary aqueous solution of two drugs, namely, promazine hydrochloride (PZ) and chlorpromazine hydrochloride (CPZ) using a vapor pressure osmometer at 298.15 K. The observed critical micelle concentration (cmc) agrees excellently with the available literature data. The measurements are extended to aqueous ternary solutions containing fixed a concentration of alpha-cyclodextrin (alpha-CD) of 0.1 mol kg(-1) and varied concentrations (approximately 0.005-0.2 mol kg(-1)) of drugs at 298.15 K. It has been found that the cmc values increase by the addition of alpha-CD. The mean molal activity coefficients of the ions and the activity coefficient of alpha-CD in binary as well as ternary solutions were obtained, which have been further used to calculate the excess Gibbs free energies and transfer Gibbs free energies. The lowering of the activity coefficients of ions and of alpha-CD is attributed to the existence of host-guest (inclusion)-type complex equilibria. It is suggested that CPZ forms 2:1 and 1:1 complexed species with alpha-CD, while PZ forms only 1:1 complexed species. The salting constant (ks) values are determined at 298.15 K for promazine-alpha-CD and chlorpromazine-alpha-CD complexes, respectively, by following the method based on the application of the McMillan-Mayer theory of virial coefficients to transfer free energy data. It is noted that the presence of chlorine in the drug molecule imparts better complexing capacity, the effect of which gets attenuated as a result of hydrophobic interaction. The results are discussed from the point of view of associative equilibria before the cmc and complexed equilibria for binary and ternary solutions, respectively.

Structure and mechanism of the phage T4 recombination mediator protein UvsY

DOE PAGES

Gajewski, Stefan; Waddell, Michael Brett; Vaithiyalingam, Sivaraja; ...

2016-03-07

The UvsY recombination mediator protein is critical for efficient homologous recombination in bacteriophage T4 and is the functional analog of the eukaryotic Rad52 protein. During T4 homologous recombination, the UvsX recombinase has to compete with the prebound gp32 single-stranded binding protein for DNA-binding sites and UvsY stimulates this filament nucleation event. We report here the crystal structure of UvsY in four similar open-barrel heptameric assemblies and provide structural and biophysical insights into its function. The UvsY heptamer was confirmed in solution by centrifugation and light scattering, and thermodynamic analyses revealed that the UvsY–ssDNA interaction occurs within the assembly via twomore » distinct binding modes. Using surface plasmon resonance, we also examined the binding of UvsY to both ssDNA and the ssDNA–gp32 complex. These analyses confirmed that ssDNA can bind UvsY and gp32 independently and also as a ternary complex. They also showed that residues located on the rim of the heptamer are required for optimal binding to ssDNA, thus identifying the putative ssDNA-binding surface. We propose a model in which UvsY promotes a helical ssDNA conformation that disfavors the binding of gp32 and initiates the assembly of the ssDNA–UvsX filament.« less

In situ spectroscopic evidence for neptunium(V)-carbonate inner-sphere and outer-sphere ternary surface complexes on hematite surfaces.

PubMed

Arai, Yuji; Moran, P B; Honeyman, B D; Davis, J A

2007-06-01

Np(V) surface speciation on hematite surfaces at pH 7-9 under pC2 = 10(-3.45) atm was investigated using X-ray absorption spectroscopy (XAS). In situ XAS analyses suggest that bis-carbonato inner-sphere and tris-carbonato outer-sphere ternary surface species coexist at the hematite-water interface at pH 7-8.8, and the fraction of outer-sphere species gradually increases from 27 to 54% with increasing pH from 7 to 8.8. The results suggest that the heretofore unknown Np(V)-carbonato ternary surface species may be important in predicting the fate and transport of Np(V) in the subsurface environment down gradient of high-level nuclear waste respositories.

Retention Mechanisms of Citric Acid in Ternary Kaolinite-Fe(III)-Citrate Acid Systems Using Fe K-edge EXAFS and L3,2-edge XANES Spectroscopy

PubMed Central

Yang, Jianjun; Wang, Jian; Pan, Weinan; Regier, Tom; Hu, Yongfeng; Rumpel, Cornelia; Bolan, Nanthi; Sparks, Donald

2016-01-01

Organic carbon (OC) stability in tropical soils is strongly interlinked with multivalent cation interaction and mineral association. Low molecular weight organic acids (LMWOAs) represent the readily biodegradable OC. Therefore, investigating retention mechanisms of LMWOAs in mineral-cation-LMWOAs systems is critical to understanding soil C cycling. Given the general acidic conditions and dominance of kaolinite in tropical soils, we investigated the retention mechanisms of citric acid (CA) in kaolinite-Fe(III)-CA systems with various Fe/CA molar ratios at pH ~3.5 using Fe K-edge EXAFS and L3,2-edge XANES techniques. With Fe/CA molar ratios >2, the formed ferrihydrite mainly contributed to CA retention through adsorption and/or coprecipitation. With Fe/CA molar ratios from 2 to 0.5, ternary complexation of CA to kaolinite via a five-coordinated Fe(III) bridge retained higher CA than ferrihydrite-induced adsorption and/or coprecipitation. With Fe/CA molar ratios ≤0.5, kaolinite-Fe(III)-citrate complexation preferentially occurred, but less CA was retained than via outer-sphere kaolinite-CA complexation. This study highlighted the significant impact of varied Fe/CA molar ratios on CA retention mechanisms in kaolinite-Fe(III)-CA systems under acidic conditions, and clearly showed the important contribution of Fe-bridged ternary complexation on CA retention. These findings will enhance our understanding of the dynamics of CA and other LMWOAs in tropical soils. PMID:27212680

Gold nanoparticles interacting with β-cyclodextrin-phenylethylamine inclusion complex: a ternary system for photothermal drug release.

PubMed

Sierpe, Rodrigo; Lang, Erika; Jara, Paul; Guerrero, Ariel R; Chornik, Boris; Kogan, Marcelo J; Yutronic, Nicolás

2015-07-22

We report the synthesis of a 1:1 β-cyclodextrin-phenylethylamine (βCD-PhEA) inclusion complex (IC) and the adhesion of gold nanoparticles (AuNPs) onto microcrystals of this complex, which forms a ternary system. The formation of the IC was confirmed by powder X-ray diffraction and NMR analyses ((1)H and ROESY). The stability constant of the IC (760 M(-1)) was determined using the phase solubility method. The adhesion of AuNPs was obtained using the magnetron sputtering technique, and the presence of AuNPs was confirmed using UV-vis spectroscopy (surface plasmon resonance effect), which showed an absorbance at 533 nm. The powder X-ray diffractograms of βCD-PhEA were similar to those of the crystals decorated with AuNPs. A comparison of the one- and two-dimensional NMR spectra of the IC with and without AuNPs suggests partial displacement of the guest to the outside of the βCD due to attraction toward AuNPs, a characteristic tropism effect. The size, morphology, and distribution of the AuNPs were analyzed using TEM and SEM. The average size of the AuNPs was 14 nm. Changes in the IR and Raman spectra were attributed to the formation of the complex and to the specific interactions of this group with the AuNPs. Laser irradiation assays show that the ternary system βCD-PhEA-AuNPs in solution enables the release of the guest.

Reversible stalling of transcription elongation complexes by high pressure.

PubMed

Erijman, L; Clegg, R M

1998-07-01

We have investigated the effect of high hydrostatic pressure on the stability of RNA polymerase molecules during transcription. RNA polymerase molecules participating in stalled or active ternary transcribing complexes do not dissociate from the template DNA and nascent RNA at pressures up to 180 MPa. A lower limit for the free energy of stabilization of an elongating ternary complex relative to the quaternary structure of the free RNAP molecules is estimated to be 20 kcal/mol. The rate of elongation decreases at high pressure; transcription completely halts at sufficiently high pressure. The overall rate of elongation has an apparent activation volume (DeltaVdouble dagger) of 55-65 ml . mol-1 (at 35 degrees C). The pressure-stalled transcripts are stable and resume elongation at the prepressure rate upon decompression. The efficiency of termination decreases at the rho-independent terminator tR2 after the transcription reaction has been exposed to high pressure. This suggests that high pressure modifies the ternary complex such that termination is affected in a manner different from that of elongation. The solvent and temperature dependence of the pressure-induced inhibition show evidence for major conformational changes in the core polymerase enzyme during RNA synthesis. It is proposed that the inhibition of the elongation phase of the transcription reaction at elevated pressures is related to a reduction of the partial specific volume of the RNA polymerase molecule; under high pressure, the RNA polymerase molecule does not have the necessary structural flexibility required for the protein to translocate.

Retention mechanisms of citric acid in ternary kaolinite-Fe(III)-citrate acid systems using Fe K-edge EXAFS and L 3,2-edge XANES spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Jianjun; Wang, Jian; Pan, Weinan

Organic carbon (OC) stability in tropical soils is strongly interlinked with multivalent cation interaction and mineral association. Low molecular weight organic acids (LMWOAs) represent the readily biodegradable OC. Therefore, investigating retention mechanisms of LMWOAs in mineral-cation-LMWOAs systems is critical to understanding soil C cycling. Given the general acidic conditions and dominance of kaolinite in tropical soils, we investigated the retention mechanisms of citric acid (CA) in kaolinite-Fe(III)-CA systems with various Fe/CA molar ratios at pH ~3.5 using Fe K-edge EXAFS and L- 3,2-edge XANES techniques. With Fe/CA molar ratios >2, the formed ferrihydrite mainly contributed to CA retention through adsorptionmore » and/or coprecipitation. With Fe/CA molar ratios from 2 to 0.5, ternary complexation of CA to kaolinite via a five-coordinated Fe(III) bridge retained higher CA than ferrihydrite-induced adsorption and/or coprecipitation. With Fe/CA molar ratios ≤ 0.5, kaolinite-Fe(III)-citrate complexation preferentially occurred, but less CA was retained than via outer-sphere kaolinite-CA complexation. This study highlighted the significant impact of varied Fe/CA molar ratios on CA retention mechanisms in kaolinite-Fe(III)-CA systems under acidic conditions, and clearly showed the important contribution of Fe-bridged ternary complexation on CA retention. In conclusion, these findings will enhance our understanding of the dynamics of CA and other LMWOAs in tropical soils.« less

Retention mechanisms of citric acid in ternary kaolinite-Fe(III)-citrate acid systems using Fe K-edge EXAFS and L 3,2-edge XANES spectroscopy

DOE PAGES

Yang, Jianjun; Wang, Jian; Pan, Weinan; ...

2016-05-23

Organic carbon (OC) stability in tropical soils is strongly interlinked with multivalent cation interaction and mineral association. Low molecular weight organic acids (LMWOAs) represent the readily biodegradable OC. Therefore, investigating retention mechanisms of LMWOAs in mineral-cation-LMWOAs systems is critical to understanding soil C cycling. Given the general acidic conditions and dominance of kaolinite in tropical soils, we investigated the retention mechanisms of citric acid (CA) in kaolinite-Fe(III)-CA systems with various Fe/CA molar ratios at pH ~3.5 using Fe K-edge EXAFS and L- 3,2-edge XANES techniques. With Fe/CA molar ratios >2, the formed ferrihydrite mainly contributed to CA retention through adsorptionmore » and/or coprecipitation. With Fe/CA molar ratios from 2 to 0.5, ternary complexation of CA to kaolinite via a five-coordinated Fe(III) bridge retained higher CA than ferrihydrite-induced adsorption and/or coprecipitation. With Fe/CA molar ratios ≤ 0.5, kaolinite-Fe(III)-citrate complexation preferentially occurred, but less CA was retained than via outer-sphere kaolinite-CA complexation. This study highlighted the significant impact of varied Fe/CA molar ratios on CA retention mechanisms in kaolinite-Fe(III)-CA systems under acidic conditions, and clearly showed the important contribution of Fe-bridged ternary complexation on CA retention. In conclusion, these findings will enhance our understanding of the dynamics of CA and other LMWOAs in tropical soils.« less

Use of spectroscopic technique to develop a reagent for Mo(VI) utilizing micellar effects on complex formation

NASA Astrophysics Data System (ADS)

Taşcioğlu, Sülin; Kaki, E.; Taşcioğlu, Senay

2012-09-01

Ultraviolet and visible spectral properties of aqueous solutions of molybdenum(VI) (Mo), gallic acid (GA), Lalanine (Ala), and L-Phenylalanine (Phe), and of their binary and ternary solutions were investigated in the absence and presence of anionic, cationic, and nonionic surfactant micelles. Evaluation of the spectra in a comparative way revealed that both Ala and Phe form ternary complexes with Mo and GA. The formation of a quaternary complex between Mo, GA, Phe, and cetyltrimethylammonium bromide at pH 4.5 provided a reagent system with a strikingly high sensitivity (1.2•106 l/(mol•cm)) for use in the spectrophotometric determination of Mo. A mechanism of micellar effects was discussed in terms of the substrate molecular charge and hydrophobicity, and rationalized on the basis of the spectral data obtained above and below the isoelectric pH of the amino acids.

Synthesis, characterization, DNA-binding study and anticancer properties of ternary metal(II) complexes of edda and an intercalating ligand.

PubMed

Ng, Chew Hee; Kong, King Chow; Von, Sze Tin; Balraj, Pauline; Jensen, Paul; Thirthagiri, Eswary; Hamada, Hirokazu; Chikira, Makoto

2008-01-28

A series of ternary metal(ii) complexes {M(phen)(edda); 1a (Cu), 1b (Co), 1c (Zn), 1d (Ni); H(2)edda = N,N(')-ethylenediaminediacetic acid} of N,N'-ethylene-bridged diglycine and 1,10-phenanthroline were synthesized and characterized by elemental analysis, FTIR, UV-visible spectroscopy and magnetic susceptibility measurement. The interaction of these complexes with DNA was investigated using CD and EPR spectroscopy. MTT assay results of 1a-1c , screened on MCF-7 cancer cell lines, show that synergy between the metal and ligands results in significant enhancement of their antiproliferative properties. Preliminary results from apoptosis and cell cycle analyses with flow cytometry are reported. seems to be able to induce cell cycle arrest at G(0)/G(1). The crystal structure of 1a is also included.

Gene delivery through the use of a hyaluronate-associated intracellularly degradable cross-linked polyethyleneimine

PubMed Central

Xu, Peisheng; Quick, Griffin; Yeo, Yoon

2009-01-01

For a non-viral gene delivery system to be clinically effective, it should be non-toxic, compatible with biological components, and highly efficient in gene transfection. With this goal in mind, we investigated the gene delivery efficiency of a ternary complex consisting of DNA, an intracellularly degradable polycation, and sodium hyaluronate (DPH complex). Here, we report that the DPH ternary complex achieved significantly higher transfection efficiency than other polymer systems, especially in the presence of serum. The high transfection efficiency and serum tolerance of DPH are attributed to a unique interplay between CLPEI and HA, which leads to (i) the improved stability of DNA in the extracellular environment and at the early stage of intracellular trafficking and (ii) timely dissociation of the DNA-polymer complex. This study reinforces findings of earlier studies that emphasized each step as a bottleneck for efficient gene delivery; yet, it is the first to show that it is possible to overcome these obstacles simultaneously by taking advantage of two distinctive approaches. PMID:19631979

TRBP recruits the Dicer complex to Ago2 for microRNA processing and gene silencing.

PubMed

Chendrimada, Thimmaiah P; Gregory, Richard I; Kumaraswamy, Easwari; Norman, Jessica; Cooch, Neil; Nishikura, Kazuko; Shiekhattar, Ramin

2005-08-04

MicroRNAs (miRNAs) are generated by a two-step processing pathway to yield RNA molecules of approximately 22 nucleotides that negatively regulate target gene expression at the post-transcriptional level. Primary miRNAs are processed to precursor miRNAs (pre-miRNAs) by the Microprocessor complex. These pre-miRNAs are cleaved by the RNase III Dicer to generate mature miRNAs that direct the RNA-induced silencing complex (RISC) to messenger RNAs with complementary sequence. Here we show that TRBP (the human immunodeficiency virus transactivating response RNA-binding protein), which contains three double-stranded, RNA-binding domains, is an integral component of a Dicer-containing complex. Biochemical analysis of TRBP-containing complexes revealed the association of Dicer-TRBP with Argonaute 2 (Ago2), the catalytic engine of RISC. The physical association of Dicer-TRBP and Ago2 was confirmed after the isolation of the ternary complex using Flag-tagged Ago2 cell lines. In vitro reconstitution assays demonstrated that TRBP is required for the recruitment of Ago2 to the small interfering RNA (siRNA) bound by Dicer. Knockdown of TRBP results in destabilization of Dicer and a consequent loss of miRNA biogenesis. Finally, depletion of the Dicer-TRBP complex via exogenously introduced siRNAs diminished RISC-mediated reporter gene silencing. These results support a role of the Dicer-TRBP complex not only in miRNA processing but also as a platform for RISC assembly.

A high-performance ternary Si composite anode material with crystal graphite core and amorphous carbon shell

NASA Astrophysics Data System (ADS)

Sui, Dong; Xie, Yuqing; Zhao, Weimin; Zhang, Hongtao; Zhou, Ying; Qin, Xiting; Ma, Yanfeng; Yang, Yong; Chen, Yongsheng

2018-04-01

Si is a promising anode material for lithium-ion batteries, but suffers from sophisticated engineering structures and complex fabrication processes that pose challenges for commercial application. Herein, a ternary Si/graphite/pyrolytic carbon (SiGC) anode material with a structure of crystal core and amorphous shell using low-cost raw materials is developed. In this ternary SiGC composite, Si component exists as nanoparticles and is spread on the surface of the core graphite flakes while the sucrose-derived pyrolytic carbon further covers the graphite/Si components as the amorphous shell. With this structure, Si together with the graphite contributes to the high specific capacity of this Si ternary material. Also the graphite serves as the supporting and conducting matrix and the amorphous shell carbon could accommodate the volume change effect of Si, reinforces the integrity of the composite architecture, and prevents the graphite and Si from direct exposing to the electrolyte. The optimized ternary SiGC composite displays high reversible specific capacity of 818 mAh g-1 at 0.1 A g-1, initial Coulombic efficiency (CE) over 80%, and excellent cycling stability at 0.5 A g-1 with 83.6% capacity retention (∼610 mAh g-1) after 300 cycles.

Structure/cleavage-based insights into helical perturbations at bulge sites within T. thermophilus Argonaute silencing complexes

PubMed Central

Sheng, Gang; Gogakos, Tasos; Wang, Jiuyu; Zhao, Hongtu; Serganov, Artem; Juranek, Stefan

2017-01-01

Abstract We have undertaken a systematic structural study of Thermus thermophilus Argonaute (TtAgo) ternary complexes containing single-base bulges positioned either within the seed segment of the guide or target strands and at the cleavage site. Our studies establish that single-base bulges 7T8, 5A6 and 4A5 on the guide strand are stacked-into the duplex, with conformational changes localized to the bulge site, thereby having minimal impact on the cleavage site. By contrast, single-base bulges 6’U7’ and 6’A7’ on the target strand are looped-out of the duplex, with the resulting conformational transitions shifting the cleavable phosphate by one step. We observe a stable alignment for the looped-out 6’N7’ bulge base, which stacks on the unpaired first base of the guide strand, with the looped-out alignment facilitated by weakened Watson–Crick and reversed non-canonical flanking pairs. These structural studies are complemented by cleavage assays that independently monitor the impact of bulges on TtAgo-mediated cleavage reaction. PMID:28911094

Role of large thermal fluctuations and magnesium ions in t-RNA selectivity of the ribosome

PubMed Central

Guo, Zuojun; Gibson, Meghan; Sitha, Sanyasi; Chu, Steven; Mohanty, Udayan

2011-01-01

The fidelity of translation selection begins with the base pairing of codon-anticodon complex between the m-RNA and tRNAs. Binding of cognate and near-cognate tRNAs induces 30S subunit of the ribosome to wrap around the ternary complex, EF-Tu(GTP)aa-tRNA. We have proposed that large thermal fluctuations play a crucial role in the selection process. To test this conjecture, we have developed a theoretical technique to determine the probability that the ternary complex, as a result of large thermal fluctuations, forms contacts leading to stabilization of the GTPase activated state. We argue that the configurational searches for such processes are in the tail end of the probability distribution and show that the probability for this event is localized around the most likely configuration. Small variations in the repositioning of cognate relative to near-cognate complexes lead to rate enhancement of the cognate complex. The binding energies of over a dozen unique site-bound magnesium structural motifs are investigated and provide insights into the nature of interaction of divalent metal ions with the ribosome. PMID:21368154

Optimization of contrast-to-tissue ratio by adaptation of transmitted ternary signal in ultrasound pulse inversion imaging.

PubMed

Ménigot, Sébastien; Girault, Jean-Marc

2013-01-01

Ultrasound contrast imaging has provided more accurate medical diagnoses thanks to the development of innovating modalities like the pulse inversion imaging. However, this latter modality that improves the contrast-to-tissue ratio (CTR) is not optimal, since the frequency is manually chosen jointly with the probe. However, an optimal choice of this command is possible, but it requires precise information about the transducer and the medium which can be experimentally difficult to obtain, even inaccessible. It turns out that the optimization can become more complex by taking into account the kind of generators, since the generators of electrical signals in a conventional ultrasound scanner can be unipolar, bipolar, or tripolar. Our aim was to seek the ternary command which maximized the CTR. By combining a genetic algorithm and a closed loop, the system automatically proposed the optimal ternary command. In simulation, the gain compared with the usual ternary signal could reach about 3.9 dB. Another interesting finding was that, in contrast to what is generally accepted, the optimal command was not a fixed-frequency signal but had harmonic components.

Low Pt-content ternary PdCuPt nanodendrites: an efficient electrocatalyst for oxygen reduction reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Shaofang; Zhu, Chengzhou; Song, Junhua

2017-01-01

Dendritic nanostructures are capturing increasing attentions in electrocatalysis owing to their unique structural features and low density. Herein, we report for the first time bromide ions mediated synthesis of low-Pt-content PdCuPt ternary nanodendrites via galvanic replacement reaction between Pt precursor and PdCu template in aqueous solution. The experimental results show that the ternary PdCuPt nanodendrites present enhanced electrocatalytic performance for oxygen reduction reaction in acid solution compared with commercial Pt/C as well as some state-of-the-art catalysts. In details, the mass activity of the PdCuPt catalyst with optimized composition is 1.73 A/mgPt at 0.85 V vs RHE, which is 14 timesmore » higher than that of commercial Pt/C catalyst. Moreover, the long-term stability test demonstrates its better durability in acid solution. After 5k cycles, there is still 70% electrochemical surface area maintained. This method provides an efficient way to synthesize trimetallic alloys with controllable composition and specific structure for oxygen reduction reaction.« less

A mediator-free glucose biosensor based on glucose oxidase/chitosan/α-zirconium phosphate ternary biocomposite.

PubMed

Liu, Li-Min; Wen, Jiwu; Liu, Lijun; He, Deyong; Kuang, Ren-yun; Shi, Taqing

2014-01-15

A novel glucose oxidase/chitosan/α-zirconium phosphate (GOD/chitosan/α-ZrP) ternary biocomposite was prepared by co-intercalating glucose oxidase (GOD) and chitosan into the interlayers of α-zirconium phosphate (α-ZrP) via a delamination-reassembly procedure. The results of X-ray diffraction, infrared spectroscopy, circular dichroism, and ultraviolet spectrum characterizations indicated not only the layered and hybrid structure of the GOD/chitosan/α-ZrP ternary biocomposite but also the recovered activity of the intercalated GOD improved by the co-intercalated chitosan. By depositing the GOD/chitosan/α-ZrP biocomposite film onto a glassy carbon electrode, the direct electrochemistry of the intercalated GOD was achieved with a fast electron transfer rate constant, k(s), of 7.48±3.52 s(-1). Moreover, this GOD/chitosan/α-ZrP biocomposite modified electrode exhibited a sensitive response to glucose in the linear range of 0.25-8.0 mM (R=0.9994, n=14), with a determination limit of 0.076 mM. Copyright © 2013 Elsevier Inc. All rights reserved.

E2 enzyme inhibition by stabilization of a low affinity interface with ubiquitin

PubMed Central

St-Cyr, Daniel J.; Ziemba, Amy; Garg, Pankaj; Plamondon, Serge; Auer, Manfred; Sidhu, Sachdev; Marinier, Anne; Kleiger, Gary; Tyers, Mike; Sicheri, Frank

2014-01-01

Weak protein interactions between ubiquitin and the ubiquitin-proteasome system (UPS) enzymes that mediate its covalent attachment to substrates serve to position ubiquitin for optimal catalytic transfer. We show that a small molecule inhibitor of the E2 ubiquitin conjugating enzyme Cdc34A, called CC0651, acts by trapping a weak interaction between ubiquitin and the E2 donor ubiquitin binding site. A structure of the ternary CC0651-Cdc34A-ubiquitin complex reveals that the inhibitor engages a composite binding pocket formed from Cdc34A and ubiquitin. CC0651 also suppresses the spontaneous hydrolysis rate of the Cdc34A-ubiquitin thioester, without overtly affecting the interaction between Cdc34A and the RING domain subunit of the E3 enzyme. Stabilization of the numerous other weak interactions between ubiquitin and UPS enzymes by small molecules may be a feasible strategy to selectively inhibit different UPS activities. PMID:24316736

Redox-Mediated Stabilization in Zinc Molybdenum Nitrides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arca, Elisabetta; Lany, Stephan; Perkins, John D.

We report on the theoretical prediction and experimental realization of new ternary zinc molybdenum nitride compounds. We used theory to identify previously unknown ternary compounds in the Zn-Mo-N systems, Zn 3MoN 4 and ZnMoN 2, and to analyze their bonding environment. Experiments show that Zn-Mo-N alloys can form in broad composition range from Zn 3MoN 4 to ZnMoN 2 in the wurtzite-derived structure, accommodating very large off-stoichiometry. Interestingly, the measured wurtzite-derived structure of the alloys is metastable for the ZnMoN 2 stoichiometry, in contrast to the Zn 3MoN 4 stoichiometry, where ordered wurtzite is predicted to be the ground state.more » The formation of Zn 3MoN 4-ZnMoN 2 alloy with wurtzite-derived crystal structure is enabled by the concomitant ability of Mo to change oxidation state from +VI in Zn 3MoN 4 to +IV in ZnMoN 2, and the capability of Zn to contribute to the bonding states of both compounds, an effect that we define as 'redox-mediated stabilization.' The stabilization of Mo in both the +VI and +IV oxidation states is due to the intermediate electronegativity of Zn, which enables significant polar covalent bonding in both Zn 3MoN 4 and ZnMoN 2 compounds. The smooth change in the Mo oxidation state between Zn 3MoN 4 and ZnMoN 2 stoichiometries leads to a continuous change in optoelectronic properties - from resistive and semitransparent Zn 3MoN 4 to conductive and absorptive ZnMoN 2. The reported redox-mediated stabilization in zinc molybdenum nitrides suggests there might be many undiscovered ternary compounds with one metal having an intermediate electronegativity, enabling significant covalent bonding, and another metal capable of accommodating multiple oxidation states, enabling stoichiometric flexibility.« less

Redox-Mediated Stabilization in Zinc Molybdenum Nitrides

DOE PAGES

Arca, Elisabetta; Lany, Stephan; Perkins, John D.; ...

2018-03-01

We report on the theoretical prediction and experimental realization of new ternary zinc molybdenum nitride compounds. We used theory to identify previously unknown ternary compounds in the Zn-Mo-N systems, Zn 3MoN 4 and ZnMoN 2, and to analyze their bonding environment. Experiments show that Zn-Mo-N alloys can form in broad composition range from Zn 3MoN 4 to ZnMoN 2 in the wurtzite-derived structure, accommodating very large off-stoichiometry. Interestingly, the measured wurtzite-derived structure of the alloys is metastable for the ZnMoN 2 stoichiometry, in contrast to the Zn 3MoN 4 stoichiometry, where ordered wurtzite is predicted to be the ground state.more » The formation of Zn 3MoN 4-ZnMoN 2 alloy with wurtzite-derived crystal structure is enabled by the concomitant ability of Mo to change oxidation state from +VI in Zn 3MoN 4 to +IV in ZnMoN 2, and the capability of Zn to contribute to the bonding states of both compounds, an effect that we define as 'redox-mediated stabilization.' The stabilization of Mo in both the +VI and +IV oxidation states is due to the intermediate electronegativity of Zn, which enables significant polar covalent bonding in both Zn 3MoN 4 and ZnMoN 2 compounds. The smooth change in the Mo oxidation state between Zn 3MoN 4 and ZnMoN 2 stoichiometries leads to a continuous change in optoelectronic properties - from resistive and semitransparent Zn 3MoN 4 to conductive and absorptive ZnMoN 2. The reported redox-mediated stabilization in zinc molybdenum nitrides suggests there might be many undiscovered ternary compounds with one metal having an intermediate electronegativity, enabling significant covalent bonding, and another metal capable of accommodating multiple oxidation states, enabling stoichiometric flexibility.« less

Sol-Gel-Synthesis of Nanoscopic Complex Metal Fluorides

PubMed Central

Rehmer, Alexander; Scheurell, Kerstin; Scholz, Gudrun; Kemnitz, Erhard

2017-01-01

The fluorolytic sol-gel synthesis for binary metal fluorides (AlF3, CaF2, MgF2) has been extended to ternary and quaternary alkaline earth metal fluorides (CaAlF5, Ca2AlF7, LiMgAlF6). The formation and crystallization of nanoscopic ternary CaAlF5 and Ca2AlF7 sols in ethanol were studied by 19F liquid and solid state NMR (nuclear magnetic resonance) spectroscopy, as well as transmission electron microscopy (TEM). The crystalline phases of the annealed CaAlF5, Ca2AlF7, and LiMgAlF6 xerogels between 500 and 700 °C could be determined by X-ray powder diffraction (XRD) and 19F solid state NMR spectroscopy. The thermal behavior of un-annealed nanoscopic ternary and quaternary metal fluoride xerogels was ascertained by thermal analysis (TG/DTA). The obtained crystalline phases of CaAlF5 and Ca2AlF7 derived from non-aqueous sol-gel process were compared to crystalline phases from the literature. The corresponding nanoscopic complex metal fluoride could provide a new approach in ceramic and luminescence applications. PMID:29099086

Copper(II) ions interactions in the systems with triamines and ATP. Potentiometric and spectroscopic studies.

PubMed

Hoffmann, S K; Goslar, J; Bregier-Jarzebowska, R; Gasowska, A; Zalewska, A; Lomozik, L

2017-12-01

The mode of interaction and thermodynamic stability of complexes formed in binary and ternary Cu(II)/ATP/triamines systems were studied using potentiometric and spectroscopic (NMR, EPR, UV-Vis) methods. It was found that in binary metal-free systems ATP/H x PA species are formed (PA: Spd=spermidine or 3,3-tri=1,7-diamino-4-azaheptane) where the phosphate groups from nucleotides are preferred negative centers and protonated amine groups of amines are positive centers of reaction. In the ternary systems Cu/ATP/H x (PA) as well as Cu/(ATP)(PA) species are formed. The type of the formed Cu(II) complexes depends on pH of the solution. For a low pH value the complexation appears between Cu(II) and ATP molecules via oxygen atoms of phosphate groups. For a very high pH value, where ATP is hydrolyzed, the Cu(II) ions are bound to the nitrogen atoms of polyamine molecules. We did not detect any direct coordination of the N7 nitrogen atom of adenosine to Cu(II) ions. It means that the CuN7 interaction is an indirect type and can be due to noncovalent interplay including water molecule. EPR studies were performed at glassy state (77K) after a fast freezing both for binary and ternary systems. The glassy state EPR spectra do not reflect species identified in titration studies indicating significant effect of rapid temperature decrease on equilibrium of Cu(II) complexes. We propose the molecular structure of all the studied complexes at the glassy state deduced from EPR and optical spectroscopy results. Copyright © 2017 Elsevier Inc. All rights reserved.

Host protein BSL1 associates with Phytophthora infestans RXLR effector AVR2 and the Solanum demissum Immune receptor R2 to mediate disease resistance.

PubMed

Saunders, Diane G O; Breen, Susan; Win, Joe; Schornack, Sebastian; Hein, Ingo; Bozkurt, Tolga O; Champouret, Nicolas; Vleeshouwers, Vivianne G A A; Birch, Paul R J; Gilroy, Eleanor M; Kamoun, Sophien

2012-08-01

Plant pathogens secrete effector proteins to modulate plant immunity and promote host colonization. Plant nucleotide binding leucine-rich repeat (NB-LRR) immunoreceptors recognize specific pathogen effectors directly or indirectly. Little is known about how NB-LRR proteins recognize effectors of filamentous plant pathogens, such as Phytophthora infestans. AVR2 belongs to a family of 13 sequence-divergent P. infestans RXLR effectors that are differentially recognized by members of the R2 NB-LRR family in Solanum demissum. We report that the putative plant phosphatase BSU-LIKE PROTEIN1 (BSL1) is required for R2-mediated perception of AVR2 and resistance to P. infestans. AVR2 associates with BSL1 and mediates the interaction of BSL1 with R2 in planta, possibly through the formation of a ternary complex. Strains of P. infestans that are virulent on R2 potatoes express an unrecognized form, Avr2-like (referred to as A2l). A2L can still interact with BSL1 but does not promote the association of BSL1 with R2. Our findings show that recognition of the P. infestans AVR2 effector by the NB-LRR protein R2 requires the putative phosphatase BSL1. This reveals that, similar to effectors of phytopathogenic bacteria, recognition of filamentous pathogen effectors can be mediated via a host protein that interacts with both the effector and the NB-LRR immunoreceptor.

Synthesis of graphenized Au/ZnO plasmonic nanocomposites for simultaneous sunlight mediated photo-catalysis and anti-microbial activity.

PubMed

Juneja, Subhavna; Madhavan, Ashwathi Asha; Ghosal, Anujit; Ghosh Moulick, Ranjita; Bhattacharya, Jaydeep

2018-04-05

Sunlight mediated photo-degradation and anti-bacterial activity of hetero junctioned plasmonic binary (Au/ZnO, RGO/ZnO) and ternary (RGO/Au/ZnO) nanocomposites (NC) have been reported. Higher photo-charge carrier generation, increased charge separation, improved active sites for catalysis, enhanced LSPR and larger photo-response regions have been achieved. Decoration with Au nanoparticles (ca. 11 ± 3 and 48 ± 5 nm) and RGO of ZnO (3D/1D) microstructures (aspect ratio 15.18) provides ternary NCs an edge over mono/bi component catalysts. The ternary NC have shown improved dye degradation capacity with 100% efficiency (5 μM MB solution) and average adsorption degradation capacity (Q°) of 83.34 mg/g within 30 min of sunlight exposure (900 ± 30 Wm -2 ). Elaborated studies by varying reaction parameters like initial dye concentration, contact time, type of NCs and initial loading of NCs reveals pseudo first order degradation kinetics. 100% microbial killing of Gram positive S.aureus strain with 60 μg/ml of NC using sunlight as activator has proven the simultaneous multiple functionality of the NC. Further, facile green one pot hydrothermal synthesis with water as reaction medium, absence of photo-corrosion of NCs, regeneration ability (ca. 90% for 10 μM solution) of NCs, projects a broader potential application of the synthesized NCs and could reduce the continuous requirement of such material, limiting the environmental toxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

Model of a ternary complex between activated factor VII, tissue factor and factor IX.

PubMed

Chen, Shu-wen W; Pellequer, Jean-Luc; Schved, Jean-François; Giansily-Blaizot, Muriel

2002-07-01

Upon binding to tissue factor, FVIIa triggers coagulation by activating vitamin K-dependent zymogens, factor IX (FIX) and factor X (FX). To understand recognition mechanisms in the initiation step of the coagulation cascade, we present a three-dimensional model of the ternary complex between FVIIa:TF:FIX. This model was built using a full-space search algorithm in combination with computational graphics. With the known crystallographic complex FVIIa:TF kept fixed, the FIX docking was performed first with FIX Gla-EGF1 domains, followed by the FIX protease/EGF2 domains. Because the FIXa crystal structure lacks electron density for the Gla domain, we constructed a chimeric FIX molecule that contains the Gla-EGF1 domains of FVIIa and the EGF2-protease domains of FIXa. The FVIIa:TF:FIX complex has been extensively challenged against experimental data including site-directed mutagenesis, inhibitory peptide data, haemophilia B database mutations, inhibitor antibodies and a novel exosite binding inhibitor peptide. This FVIIa:TF:FIX complex provides a powerful tool to study the regulation of FVIIa production and presents new avenues for developing therapeutic inhibitory compounds of FVIIa:TF:substrate complex.

Aqueous V(V)-peroxo-amino acid chemistry. Synthesis, structural and spectroscopic characterization of unusual ternary dinuclear tetraperoxo vanadium(V)-glycine complexes.

PubMed

Gabriel, C; Kaliva, M; Venetis, J; Baran, P; Rodriguez-Escudero, I; Voyiatzis, G; Zervou, M; Salifoglou, A

2009-01-19

Vanadium participation in cellular events entails in-depth comprehension of its soluble and bioavailable forms bearing physiological ligands in aqueous distributions of binary and ternary systems. Poised to understand the ternary V(V)-H(2)O(2)-amino acid interactions relevant to that metal ion's biological role, we have launched synthetic efforts involving the physiological ligands glycine and H(2)O(2). In a pH-specific fashion, V(2)O(5), glycine, and H(2)O(2) reacted and afforded the unusual complexes (H(3)O)(2)[V(2)(O)(2)(mu(2):eta(2):eta(1)-O(2))(2)(eta(2)-O(2))(2)(C(2)H(5)NO(2))] x 5/4 H(2)O (1) and K(2)[V(2)(O)(2)(mu(2):eta(2):eta(1)-O(2))(2)(eta(2)-O(2))(2)(C(2)H(5)NO(2))] x H(2)O (2). 1 crystallizes in the triclinic space group P1, with a = 7.805(4) A, b = 8.134(5) A, c = 12.010(7) A, alpha = 72.298(9) degrees, beta = 72.991(9) degrees, gamma = 64.111(9) degrees, V = 641.9(6) A(3), and Z = 2. 2 crystallizes in the triclinic space group P1, with a = 7.6766(9) A, b = 7.9534(9) A, c = 11.7494(13) A, alpha = 71.768(2) degrees, beta = 73.233(2) degrees, gamma = 65.660(2) degrees, V = 610.15(12) A(3), and Z = 2. Both complexes 1 and 2 were characterized by UV/visible, LC-MS, FT-IR, Raman, NMR spectroscopy, cyclic voltammetry, and X-ray crystallography. The structures of 1 and 2 reveal the presence of unusual ternary dinuclear vanadium-tetraperoxo-glycine complexes containing [(V(V)=O)(O(2))(2)](-) units interacting through long V-O bonds and an effective glycinate bridge. The latter ligand is present in the dianionic assembly as a bidentate moiety spanning both V(V) centers in a zwitterionic form. The collective physicochemical properties of the two ternary species 1 and 2 project the chemical role of the low molecular mass biosubstrate glycine in binding V(V)-diperoxo units, thereby stabilizing a dinuclear V(V)-tetraperoxo dianion. Structural comparisons of the anions in 1 and 2 with other known dinuclear V(V)-tetraperoxo binary anionic species provide insight into the chemical reactivity of V(V)-diperoxo species in key cellular events such as insulin mimesis and antitumorigenicity, potentially modulated by the presence of glycinate and hydrogen peroxide.

Structure of the E6/E6AP/p53 complex required for HPV-mediated degradation of p53

PubMed Central

Martinez-Zapien, Denise; Ruiz, Francesc Xavier; Poirson, Juline; Mitschler, André; Ramirez-Ramos, Juan; Forster, Anne; Cousido-Siah, Alexandra; Masson, Murielle; Pol, Scott Vande; Podjarny, Alberto; Travé, Gilles; Zanier, Katia

2015-01-01

Summary The p53 pro-apoptotic tumor suppressor is mutated or functionally altered in most cancers. In epithelial tumors induced by “high-risk” mucosal Human Papillomaviruses (hrm-HPVs), including human cervical carcinoma and a growing number of head-and-neck cancers 1, p53 is degraded by the viral oncoprotein E6 2. In this process, E6 binds to a short LxxLL consensus sequence within the cellular ubiquitin ligase E6AP 3. Subsequently, the E6/E6AP heterodimer recruits and degrades p53 4. Neither E6 nor E6AP are separately able to recruit p53 3,5, and the precise mode of assembly of E6, E6AP and p53 is unknown. Here, we solved the crystal structure of a ternary complex comprising full-length HPV16 E6, the LxxLL motif of E6AP and the core domain of p53. The LxxLL motif of E6AP renders the conformation of E6 competent for interaction with p53 by structuring a p53-binding cleft on E6. Mutagenesis of critical positions at the E6-p53 interface disrupts p53 degradation. The E6-binding site of p53 is distal from previously described DNA- and protein-binding surfaces of the core domain. This suggests that, in principle, E6 may avoid competition with cellular factors by targeting both free and bound p53 molecules. The E6/E6AP/p53 complex represents a prototype of viral hijacking of both the ubiquitin-mediated protein degradation pathway and the p53 tumor suppressor pathway. The present structure provides a framework for the design of inhibitory therapeutic strategies against HPV-mediated oncogenesis. PMID:26789255

Efficient double-quenching of electrochemiluminescence from CdS:Eu QDs by hemin-graphene-Au nanorods ternary composite for ultrasensitive immunoassay

PubMed Central

Liu, Jing; Cui, Meirong; Zhou, Hong; Zhang, Shusheng

2016-01-01

A novel ternary composite of hemin-graphene-Au nanorods (H-RGO-Au NRs) with high electrocatalytic activity was synthesized by a simple method. And this ternary composite was firstly used in construction of electrochemiluminescence (ECL) immunosensor due to its double-quenching effect of quantum dots (QDs). Based on the high electrocatalytic activity of ternary complexes for the reduction of H2O2 which acted as the coreactant of QDs-based ECL, as a result, the ECL intensity of QDs decreased. Besides, due to the ECL resonance energy transfer (ECL-RET) strategy between the large amount of Au nanorods (Au NRs) on the ternary composite surface and the CdS:Eu QDs, the ECL intensity of QDs was further quenched. Based on the double-quenching effect, a novel ultrasensitive ECL immunoassay method for detection of carcinoembryonic antigen (CEA) which is used as a model biomarker analyte was proposed. The designed immunoassay method showed a linear range from 0.01 pg mL−1 to 1.0 ng mL−1 with a detection limit of 0.01 pg mL−1. The method showing low detection limit, good stability and acceptable fabrication reproducibility, provided a new approach for ECL immunoassay sensing and significant prospect for practical application. PMID:27460868

Xenon and Other Volatile Anesthetics Change Domain Structure in Model Lipid Raft Membranes

PubMed Central

Weinrich, Michael; Worcester, David L.

2014-01-01

Inhalation anesthetics have been in clinical use for over 160 years, but the molecular mechanisms of action continue to be investigated. Direct interactions with ion channels received much attention after it was found that anesthetics do not change the structure of homogeneous model membranes. However, it was recently found that halothane, a prototypical anesthetic, changes domain structure of a binary lipid membrane. The noble gas xenon is an excellent anesthetic and provides a pivotal test of the generality of this finding, extended to ternary lipid raft mixtures. We report that xenon and conventional anesthetics change the domain equilibrium in two canonical ternary lipid raft mixtures. These findings demonstrate a membrane-mediated mechanism whereby inhalation anesthetics can affect the lipid environment of trans-membrane proteins. PMID:24299622

Ternary structure reveals mechanism of a membrane diacylglycerol kinase

PubMed Central

Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

2015-01-01

Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution. PMID:26673816

Ternary structure reveals mechanism of a membrane diacylglycerol kinase

NASA Astrophysics Data System (ADS)

Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; Basu, Shibom; Grotjohann, Ingo; Kupitz, Christopher; Rendek, Kimberley; Weierstall, Uwe; Zatsepin, Nadia A.; Cherezov, Vadim; Liu, Wei; Bandaru, Sateesh; English, Niall J.; Gati, Cornelius; Barty, Anton; Yefanov, Oleksandr; Chapman, Henry N.; Diederichs, Kay; Messerschmidt, Marc; Boutet, Sébastien; Williams, Garth J.; Marvin Seibert, M.; Caffrey, Martin

2015-12-01

Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution.

Spectral characterization, crystal structures and biological activities of iminodiacetate ternary complexes

NASA Astrophysics Data System (ADS)

Shahid, M.; Anjuli; Tasneem, Sana; Mantasha, I.; Ahamad, M. Naqi; Sama, Farasha; Fatma, Kehkeshan; Siddiqi, Zafar A.

2017-10-01

The ternary complexes with stoichiometry [M(imda)(bipy)]·6H2O (M = Cu) and [M(imda)(bipy)(H2O)]·4H2O (M = Ni, Co and Mn) where H2imda = iminodiacetic acid and bipy = 2,2‧-bipyridine, are prepared and characterized to exploit as novel antimicrobial agents and SOD mimics. The chemical structures were elucidated by IR, FAB-Mass, 1H, 13C NMR, EPR and spectral techniques. Single crystal X-ray and spectral studies of the complexes (1) and (2) have confirmed a square pyramidal geometry around Cu(II) ion while a saturated six coordinate (distorted octahedral) geometry around the Ni(II), Co(II) and Mn(II) ions due to the additional coordination from water. A supramolecular network is formed by extensive H-bonding in complex (1). The supramolecular assembly in complex (1) is additionally consolidated via the existence of unusual cyclic hexameric water clusters. The antimicrobial activities for the present complexes have been examined against Escherichia coli (K-12), Bacillus subtilis (MTC-121), Staphylococcus aureus (IOASA-22), Salmonella typhymurium (MTCC-98), Candida albicans, Aspergillus fumigatus and Penicillium marneffei. The superoxide dismutase (SOD) activity of the Cu(II) complex (1) is also assessed employing nitrobluetetrazolium (NBT) assay.

Phospholipid imprinted polymers as selective endotoxin scavengers

NASA Astrophysics Data System (ADS)

Sulc, Robert; Szekely, Gyorgy; Shinde, Sudhirkumar; Wierzbicka, Celina; Vilela, Filipe; Bauer, David; Sellergren, Börje

2017-03-01

Herein we explore phospholipid imprinting as a means to design receptors for complex glycolipids comprising the toxic lipopolysaccharide endotoxin. A series of polymerizable bis-imidazolium and urea hosts were evaluated as cationic and neutral hosts for phosphates and phosphonates, the latter used as mimics of the phospholipid head groups. The bis-imidazolium hosts interacted with the guests in a cooperative manner leading to the presence of tight and well defined 1:2 ternary complexes. Optimized monomer combinations were subsequently used for imprinting of phosphatidic acid as an endotoxin dummy template. Presence of the aforementioned ternary complexes during polymerization resulted in imprinting of lipid dimers - the latter believed to crudely mimic the endotoxin Lipid A motif. The polymers were characterized with respect to template rebinding, binding affinity, capacity and common structural properties, leading to the identification of polymers which were thereafter subjected to an industrially validated endotoxin removal test. Two of the polymers were capable of removing endotoxin down to levels well below the accepted threshold (0.005 EU/mg API) in pharmaceutical production.

Crystal Structures of MEK1 Binary and Ternary Complexes with Nucleotides and Inhibitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischmann, Thierry O.; Smith, Catherine K.; Mayhood, Todd W.

MEK1 is a member of the MAPK signal transduction pathway that responds to growth factors and cytokines. We have determined that the kinase domain spans residues 35-382 by proteolytic cleavage. The complete kinase domain has been crystallized and its X-ray crystal structure as a complex with magnesium and ATP-{gamma}S determined at 2.1 {angstrom}. Unlike crystals of a truncated kinase domain previously published, the crystals of the intact domain can be grown either as a binary complex with a nucleotide or as a ternary complex with a nucleotide and one of a multitude of allosteric inhibitors. Further, the crystals allow formore » the determination of costructures with ATP competitive inhibitors. We describe the structures of nonphosphorylated MEK1 (npMEK1) binary complexes with ADP and K252a, an ATP-competitive inhibitor (see Table 1), at 1.9 and 2.7 {angstrom} resolution, respectively. Ternary complexes have also been solved between npMEK1, a nucleotide, and an allosteric non-ATP competitive inhibitor: ATP-{gamma}S with compound 1 and ADP with either U0126 or the MEK1 clinical candidate PD325089 at 1.8, 2.0, and 2.5 {angstrom}, respectively. Compound 1 is structurally similar to PD325901. These structures illustrate fundamental differences among various mechanisms of inhibition at the molecular level. Residues 44-51 have previously been shown to play a negative regulatory role in MEK1 activity. The crystal structure of the integral kinase domain provides a structural rationale for the role of these residues. They form helix A and repress enzymatic activity by stabilizing an inactive conformation in which helix C is displaced from its active state position. Finally, the structure provides for the first time a molecular rationale that explains how mutations in MEK may lead to the cardio-facio-cutaneous syndrome.« less

Formation of a repressive complex in the mammalian circadian clock is mediated by the secondary pocket of CRY1

DOE PAGES

Michael, Alicia K.; Fribourgh, Jennifer L.; Chelliah, Yogarany; ...

2017-01-31

The basic helix-loop-helix PAS domain (bHLH-PAS) transcription factor CLOCK:BMAL1 (brain and muscle Arnt-like protein 1) sits at the core of the mammalian circadian transcription/translation feedback loop. Precise control of CLOCK:BMAL1 activity by coactivators and repressors establishes the ~24-h periodicity of gene expression. Formation of a repressive complex, defined by the core clock proteins cryptochrome 1 (CRY1):CLOCK:BMAL1, plays an important role controlling the switch from repression to activation each day. Here in this paper, we show that CRY1 binds directly to the PAS domain core of CLOCK: BMAL1, driven primarily by interaction with the CLOCK PAS-B domain. Integrative modeling and solutionmore » X-ray scattering studies unambiguously position a key loop of the CLOCK PAS-B domain in the secondary pocket of CRY1, analogous to the antenna chromophore-binding pocket of photolyase. CRY1 docks onto the transcription factor alongside the PAS domains, extending above the DNA-binding bHLH domain. Single point mutations at the interface on either CRY1 or CLOCK disrupt formation of the ternary complex, highlighting the importance of this interface for direct regulation of CLOCK:BMAL1 activity by CRY1.« less

Binding Thermodynamics of Ferredoxin:NADP+ Reductase: Two Different Protein Substrates and One Energetics

PubMed Central

Martínez-Júlvez, Marta; Medina, Milagros; Velázquez-Campoy, Adrián

2009-01-01

Abstract The thermodynamics of the formation of binary and ternary complexes between Anabaena PCC 7119 FNR and its substrates, NADP+ and Fd, or Fld, has been studied by ITC. Despite structural dissimilarities, the main difference between Fd and Fld binding to FNR relates to hydrophobicity, reflected in different binding heat capacity and number of water molecules released from the interface. At pH 8, the formation of the binary complexes is both enthalpically and entropically driven, accompanied by the protonation of at least one ionizable group. His299 FNR has been identified as the main responsible for the proton exchange observed. However, at pH 10, where no protonation occurs and intrinsic binding parameters can be obtained, the formation of the binary complexes is entropically driven, with negligible enthalpic contribution. Absence of the FMN cofactor in Fld does not alter significantly the strength of the interaction, but considerably modifies the enthalpic and entropic contributions, suggesting a different binding mode. Ternary complexes show negative cooperativity (6-fold and 11-fold reduction in binding affinity, respectively), and an increase in the enthalpic contribution (more favorable) and a decrease in the entropic contribution (less favorable), with regard to the binary complexes energetics. PMID:19527656

New insight into the ternary complexes of uranyl carbonate in seawater.

PubMed

Beccia, M R; Matara-Aho, M; Reeves, B; Roques, J; Solari, P L; Monfort, M; Moulin, C; Den Auwer, C

2017-11-01

Uranium is naturally present in seawater at trace levels and may in some cases be present at higher concentrations, due to anthropogenic nuclear activities. Understanding uranium speciation in seawater is thus essential for predicting and controlling its behavior in this specific environmental compartment and consequently, its possible impact on living organisms. The carbonato calcic complex Ca 2 UO 2 (CO 3 ) 3 was previously identified as the main uranium species in natural seawater, together with CaUO 2 (CO 3 ) 3 2- . In this work, we further investigate the role of the alkaline earth cation in the structure of the ternary uranyl-carbonate complexes. For this purpose, artificial seawater, free of Mg 2+ and Ca 2+ , using Sr 2+ as a spectroscopic probe was prepared. Combining TRLIF and EXAFS spectroscopy, together with DFT and theoretical thermodynamic calculations, evidence for the presence of Sr alkaline earth counter ion in the complex structure can be asserted. Furthermore, data suggest that when Ca 2+ is replaced by Sr 2+ , SrUO 2 (CO 3 ) 3 2- is the main complex in solution and it occurs with the presence of at least one monodentate carbonate in the uranyl coordination sphere. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cd(II) Sorption on Montmorillonite-Humic acid-Bacteria Composites

PubMed Central

Du, Huihui; Chen, Wenli; Cai, Peng; Rong, Xingmin; Dai, Ke; Peacock, Caroline L.; Huang, Qiaoyun

2016-01-01

Soil components (e.g., clays, bacteria and humic substances) are known to produce mineral-organic composites in natural systems. Herein, batch sorption isotherms, isothermal titration calorimetry (ITC), and Cd K-edge EXAFS spectroscopy were applied to investigate the binding characteristics of Cd on montmorillonite(Mont)-humic acid(HA)-bacteria composites. Additive sorption and non-additive Cd(II) sorption behaviour is observed for the binary Mont-bacteria and ternary Mont-HA-bacteria composite, respectively. Specifically, in the ternary composite, the coexistence of HA and bacteria inhibits Cd adsorption, suggesting a “blocking effect” between humic acid and bacterial cells. Large positive entropies (68.1 ~ 114.4 J/mol/K), and linear combination fitting of the EXAFS spectra for Cd adsorbed onto Mont-bacteria and Mont-HA-bacteria composites, demonstrate that Cd is mostly bound to bacterial surface functional groups by forming inner-sphere complexes. All our results together support the assertion that there is a degree of site masking in the ternary clay mineral-humic acid-bacteria composite. Because of this, in the ternary composite, Cd preferentially binds to the higher affinity components-i.e., the bacteria. PMID:26792640

Modeling the interaction of binary and ternary mixtures of estradiol with bisphenol A and bisphenol A F in an in vitro estrogen mediated transcriptional activation assay (T47D-KBluc)

EPA Science Inventory

Exposure to xenoestrogens occurs against a backdrop to physiological levels of endogenous estrogens. Endogenous estrogen levels vary from low levels in early childhood to high levels during pregnancy and in young women. For example, children have circulating E2concentrations rang...

Modeling the interaction of binary and ternary mixtures of estradiol with bisphenol A and bisphenol A F in an in vitro estrogen mediated transcriptional activation assay (T47D-KBluc).

EPA Science Inventory

Humans are concurrently exposed to xenoestrogens and to physiological levels of endogenous estrogens. Endogenous estrogen levels vary from low levels in infants to high levels during pregnancy and in young women. However, few studies have addressed how xenoestrogens interact with...

Dynamics of the Ternary Complex Formed by c-Myc Interactor JPO2, Transcriptional Co-activator LEDGF/p75, and Chromatin*

PubMed Central

Hendrix, Jelle; van Heertum, Bart; Vanstreels, Els; Daelemans, Dirk; De Rijck, Jan

2014-01-01

Lens epithelium-derived growth factor (LEDGF/p75) is a transcriptional co-activator involved in targeting human immunodeficiency virus (HIV) integration and the development of MLL fusion-mediated acute leukemia. A previous study revealed that LEDGF/p75 dynamically scans the chromatin, and upon interaction with HIV-1 integrase, their complex is locked on chromatin. At present, it is not known whether LEDGF/p75-mediated chromatin locking is typical for interacting proteins. Here, we employed continuous photobleaching and fluorescence correlation and cross-correlation spectroscopy to investigate in vivo chromatin binding of JPO2, a LEDGF/p75- and c-Myc-interacting protein involved in transcriptional regulation. In the absence of LEDGF/p75, JPO2 performs chromatin scanning inherent to transcription factors. However, whereas the dynamics of JPO2 chromatin binding are decelerated upon interaction with LEDGF/p75, very strong locking of their complex onto chromatin is absent. Similar results were obtained with the domesticated transposase PogZ, another cellular interaction partner of LEDGF/p75. We furthermore show that diffusive JPO2 can oligomerize; that JPO2 and LEDGF/p75 interact directly and specifically in vivo through the specific interaction domain of JPO2 and the C-terminal domain of LEDGF/p75, comprising the integrase-binding domain; and that modulation of JPO2 dynamics requires a functional PWWP domain in LEDGF/p75. Our results suggest that the dynamics of the LEDGF/p75-chromatin interaction depend on the specific partner and that strong chromatin locking is not a property of all LEDGF/p75-binding proteins. PMID:24634210

Construction of 6-thioguanine and 6-mercaptopurine carriers based on βcyclodextrins and gold nanoparticles.

PubMed

Sierpe, R; Noyong, Michael; Simon, Ulrich; Aguayo, D; Huerta, J; Kogan, Marcelo J; Yutronic, N

2017-12-01

As a novel strategy to overcome some of the therapeutic disadvantages of 6-thioguanine (TG) and 6-mercaptopurine (MP), we propose the inclusion of these drugs in βcyclodextrin (βCD) to form the complexes βCD-TG and βCD-MP, followed by subsequent interaction with gold nanoparticles (AuNPs), generating the ternary systems: βCD-TG-AuNPs and βCD-MP-AuNPs. This modification increased their solubility and improved their stability, betting by a site-specific transport due to their nanometric dimensions, among other advantages. The formation of the complexes was confirmed using powder X-ray diffraction, thermogravimetric analysis and one and two-dimensional NMR. A theoretical study using DFT and molecular modelling was conducted to obtain the more stable tautomeric species of TG and MP in solution and confirm the proposed inclusion geometries. The deposition of AuNPs onto βCD-TG and βCD-MP via sputtering was confirmed by UV-vis spectroscopy. Subsequently, the ternary systems were characterized by TEM, FE-SEM and EDX to directly observe the deposited AuNPs and evaluate their sizes, size dispersion, and composition. Finally, the in vitro permeability of the ternary systems was studied using parallel artificial membrane permeability assay (PAMPA). Copyright © 2017 Elsevier Ltd. All rights reserved.

Structure-based Mechanism of CMP-2-keto-3-deoxymanno-octulonic Acid Synthetase

PubMed Central

Heyes, Derren J.; Levy, Colin; Lafite, Pierre; Roberts, Ian S.; Goldrick, Marie; Stachulski, Andrew V.; Rossington, Steven B.; Stanford, Deborah; Rigby, Stephen E. J.; Scrutton, Nigel S.; Leys, David

2009-01-01

The enzyme CMP-Kdo synthetase (KdsB) catalyzes the addition of 2-keto-3-deoxymanno-octulonic acid (Kdo) to CTP to form CMP-Kdo, a key reaction in the biosynthesis of lipopolysaccharide. The reaction catalyzed by KdsB and the related CMP-acylneuraminate synthase is unique among the sugar-activating enzymes in that the respective sugars are directly coupled to a cytosine monophosphate. Using inhibition studies, in combination with isothermal calorimetry, we show the substrate analogue 2β-deoxy-Kdo to be a potent competitive inhibitor. The ligand-free Escherichia coli KdsB and ternary complex KdsB-CTP-2β-deoxy-Kdo crystal structures reveal that Kdo binding leads to active site closure and repositioning of the CTP phosphates and associated Mg2+ ion (Mg-B). Both ligands occupy conformations compatible with an Sn2-type attack on the α-phosphate by the Kdo 2-hydroxyl group. Based on strong similarity with DNA/RNA polymerases, both in terms of overall chemistry catalyzed as well as active site configuration, we postulate a second Mg2+ ion (Mg-A) is bound by the catalytically competent KdsB-CTP-Kdo ternary complex. Modeling of this complex reveals the Mg-A coordinated to the conserved Asp100 and Asp235 in addition to the CTP α-phosphate and both the Kdo carboxylic and 2-hydroxyl groups. EPR measurements on the Mn2+-substituted ternary complex support this model. We propose the KdsB/CNS sugar-activating enzymes catalyze the formation of activated sugars, such as the abundant CMP-5-N-acetylneuraminic acid, by recruitment of two Mg2+ to the active site. Although each metal ion assists in correct positioning of the substrates and activation of the α-phosphate, Mg-A is responsible for activation of the sugar-hydroxyl group. PMID:19815542

Structural Basis for Recognition of L-lysine, L-ornithine, and L-2,4-diamino Butyric Acid by Lysine Cyclodeaminase.

PubMed

Min, Kyungjin; Yoon, Hye-Jin; Matsuura, Atsushi; Kim, Yong Hwan; Lee, Hyung Ho

2018-04-30

L-pipecolic acid is a non-protein amino acid commonly found in plants, animals, and microorganisms. It is a well-known precursor to numerous microbial secondary metabolites and pharmaceuticals, including anticancer agents, immunosuppressants, and several antibiotics. Lysine cyclodeaminase (LCD) catalyzes β-deamination of L-lysine into L-pipecolic acid using β-nicotinamide adenine dinucleotide as a cofactor. Expression of a human homolog of LCD, μ-crystallin, is elevated in prostate cancer patients. To understand the structural features and catalytic mechanisms of LCD, we determined the crystal structures of Streptomyces pristinaespiralis LCD (SpLCD) in (i) a binary complex with NAD + , (ii) a ternary complex with NAD + and L-pipecolic acid, (iii) a ternary complex with NAD + and L-proline, and (iv) a ternary complex with NAD + and L-2,4-diamino butyric acid. The overall structure of SpLCD was similar to that of ornithine cyclodeaminase from Pseudomonas putida . In addition, SpLCD recognized L-lysine, L-ornithine, and L-2,4-diamino butyric acid despite differences in the active site, including differences in hydrogen bonding by Asp236, which corresponds with Asp228 from Pseudomonas putida ornithine cyclodeaminase. The substrate binding pocket of SpLCD allowed substrates smaller than lysine to bind, thus enabling binding to ornithine and L-2,4-diamino butyric acid. Our structural and biochemical data facilitate a detailed understanding of substrate and product recognition, thus providing evidence for a reaction mechanism for SpLCD. The proposed mechanism is unusual in that NAD + is initially converted into NADH and then reverted back into NAD + at a late stage of the reaction.

Hot-melt extrusion as a continuous manufacturing process to form ternary cyclodextrin inclusion complexes.

PubMed

Thiry, Justine; Krier, Fabrice; Ratwatte, Shenelka; Thomassin, Jean-Michel; Jerome, Christine; Evrard, Brigitte

2017-01-01

The aim of this study was to evaluate hot-melt extrusion (HME) as a continuous process to form cyclodextrin (CD) inclusion complexes in order to increase the solubility and dissolution rate of itraconazole (ITZ), a class II model drug molecule of the Biopharmaceutics Classification System. Different CD derivatives were tested in a 1:1 (CD:ITZ) molar ratio to obtain CD ternary inclusion complexes in the presence of a polymer, namely Soluplus ® (SOL). The CD used in this series of experiments were β-cyclodextrin (βCD), hydroxypropyl-β-cyclodextrin (HPβCD) with degrees of substitution of 0.63 and 0.87, randomly methylated β-cyclodextrin (Rameb ® ), sulfobutylether-β-cyclodextrin (Captisol ® ) and methyl-β-cyclodextrin (Crysmeb ® ). Rheology testing and mini extrusion using a conical twin screw mini extruder were performed to test the processability of the different CD mixtures since CD are not thermoplastic. This allowed Captisol ® and Crysmeb ® to be discarded from the study due to their high impact on the viscosity of the SOL/ITZ mixture. The remaining CD were processed by HME in an 18mm twin screw extruder. Saturation concentration measurements confirmed the enhancement of solubility of ITZ for the four CD formulations. Biphasic dissolution tests indicated that all four formulations had faster release profiles compared to the SOL/ITZ solid dispersion. Formulations of HPβCD 0.63 and Rameb ® even reached 95% of ITZ released in both phases after 1h. The formulations were characterized using thermal differential scanning calorimetry and attenuated total reflectance infra-red analysis. These analyses confirmed that the increased release profile was due to the formation of ternary inclusion complexes. Copyright © 2016 Elsevier B.V. All rights reserved.

mRNA 3' of the A site bound codon is located close to protein S3 on the human 80S ribosome.

PubMed

Molotkov, Maxim V; Graifer, Dmitri M; Popugaeva, Elena A; Bulygin, Konstantin N; Meschaninova, Maria I; Ven'yaminova, Aliya G; Karpova, Galina G

2006-07-01

Ribosomal proteins neighboring the mRNA downstream of the codon bound at the decoding site of human 80S ribosomes were identified using three sets of mRNA analogues that contained a UUU triplet at the 5' terminus and a perfluorophenylazide cross-linker at guanosine, adenosine or uridine residues placed at various locations 3' of this triplet. The positions of modified mRNA nucleotides on the ribosome were governed by tRNA(Phe) cognate to the UUU triplet targeted to the P site. Upon mild UV-irradiation, the mRNA analogues cross-linked preferentially to the 40S subunit, to the proteins and to a lesser extent to the 18S rRNA. Cross-linked nucleotides of 18S rRNA were identified previously. In the present study, it is shown that among the proteins the main target for cross-linking with all the mRNA analogues tested was protein S3 (homologous to prokaryotic S3, S3p); minor cross-linking to protein S2 (S5p) was also detected. Both proteins cross-linked to mRNA analogues in the ternary complexes as well as in the binary complexes (without tRNA). In the ternary complexes protein S15 (S19p) also cross-linked, the yield of the cross-link decreased significantly when the modified nucleotide moved from position +5 to position +12 with respect to the first nucleotide of the P site bound codon. In several ternary complexes minor cross-linking to protein S30 was likewise detected. The results of this study indicate that S3 is a key protein at the mRNA binding site neighboring mRNA downstream of the codon at the decoding site in the human ribosome.

Study of binary and ternary organic hybrid CdSe quantum dot photodetector

NASA Astrophysics Data System (ADS)

Ramar, M.; Kajal, S.; Pal, Prabir; Srivastava, R.; Suman, C. K.

2015-09-01

The hybrid binary and ternary photodetectors (PDs) were fabricated from P3HT-PC71BM with CdSe quantum dot (QD) materials. The absorption spectra of P3HT:PC71BM (named as B1), P3HT:CdSe (B2) and P3HT:CdSe:PC71BM (T) active blended material were analyzed in the wavelength range from 350 to 800 nm. The current density-voltage characteristics of the device were measured in dark and under illumination for study of detector detectivities and the contact with electrode. The ratio at -0.5 V for PDs B1, B2 and T is 1.1 × 102, 1.9 × 102 and 1.8 × 103, respectively. The values of detectivity for B1, B2 and T are 1 × 1010, 2 × 1010 and 7 × 1011 Jones, respectively. The for PD T is ten times in comparison with B1 and B2 PDs. The linear dynamic range (LDR) value for ternary device is more than double to both binary PDs. The absorption by CdSe QD increases the photon efficiency in the ternary detector, and at the same time the ternary detectors have high detectivity in broad spectral range. The responsivity of current to the light intensity exponent θ for detector B1, B2 and T is ~0.55, 0.55 and 0.62, respectively, which represents a complex process of electron hole generation, recombination and trapping within active material.

DNA Cleavage, Cytotoxic Activities, and Antimicrobial Studies of Ternary Copper(II) Complexes of Isoxazole Schiff Base and Heterocyclic Compounds

PubMed Central

Chityala, Vijay Kumar; Sathish Kumar, K.; Macha, Ramesh; Tigulla, Parthasarathy; Shivaraj

2014-01-01

Novel mixed ligand bivalent copper complexes [Cu. L. A. ClO 4] and [Cu. L. A] where “L” is Schiff bases, namely 2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-bromophenol (DMIIMBP)/2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-chlorophenol (DMIIMCP), and “A” is heterocyclic compound, such as 1,10-phenanthroline (phen)/2,21-bipyridyl (bipy)/8-hydroxyquinoline (oxine)/5-chloro-8-hydroxyquinoline (5-Cl-oxine), have been synthesized. These complexes have been characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, TG, and DTA. On the basis of spectral studies and analytical data, five-coordinated square pyramidal/four-coordinated square planar geometry is assigned to all complexes. The ligands and their ternary complexes with Cu(II) have been screened for antimicrobial activity against bacteria and fungi by paper disc method. The antimicrobial studies of Schiff bases and their metal complexes showed significant activity and further it is observed that the metal complexes showed more activity than corresponding Schiff bases. In vitro antitumor activity of Cu(II) complexes was assayed against human cervical carcinoma (HeLa) cancer cells and it was observed that few complexes exhibit good antitumor activity on HeLa cell lines. The DNA cleavage studies have also been carried out on pBR 322 and it is observed that these Cu(II) complexes are capable of cleaving supercoiled plasmid DNA in the presence of H2O2 and UV light. PMID:24895493

Modeling the interaction of binary and ternary mixtures of estradiol and bisphenol A or its analogues in an in vitro estrogen mediated transcriptional activation assay (T47D-KBlue).

EPA Science Inventory

Bisphenol A is a ubiquitous monomer used to manufacture polycarbonate plastics. Exposure ofhuman and wildlife populations to bisphenol A and its analogs is widespread and well documented. Bisphenol A is hypothesized to be estrogenic in both in vivo and in vitro studies and has be...

A study of interdiffusion in beta + gamma/gamma + gamma prime Ni-Cr-Al. M.S. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Carol, L. A.

1985-01-01

Ternary diffusion in the NiCrAl system at 1200 C was studied with beta + gamma/gamma + gamma prime infinite diffusion couples. Interdiffusion resulted in the formation of complex, multiphase diffusion zones. Concentration/distance profiles for Cr and Al in the phases present in the diffusion zone were measured after 200 hr. The Ni-rich portion of the NiCrAl phase diagram (1200 C) was also determined. From these data, bulk Cr and Al profiles were calculated and translated to diffusion paths on the ternary isotherm. Growth layer kinetics of the layers present in the diffusion zone were also measured.

Si-Mn/reduced graphene oxide nanocomposite anodes with enhanced capacity and stability for lithium-ion batteries.

PubMed

Park, A Reum; Kim, Jung Sub; Kim, Kwang Su; Zhang, Kan; Park, Juhyun; Park, Jong Hyeok; Lee, Joong Kee; Yoo, Pil J

2014-02-12

Although Si is a promising high-capacity anode material for Li-ion batteries (LIB), it suffers from capacity fading due to excessively large volumetric changes upon Li insertion. Nanocarbon materials have been used to enhance the cyclic stability of LIB anodes, but they have an inherently low specific capacity. To address these issues, we present a novel ternary nanocomposite of Si, Mn, and reduced graphene oxide (rGO) for LIB anodes, in which the Si-Mn alloy offers high capacity characteristics and embedded rGO nanosheets confer structural stability. Si-Mn/rGO ternary nanocomposites were synthesized by mechanical complexation and subsequent thermal reduction of mixtures of Si nanoparticles, MnO2 nanorods, and rGO nanosheets. Resulting ternary nanocomposite anodes displayed a specific capacity of 600 mAh/g with ∼90% capacity retention after 50 cycles at a current density of 100 mA/g. The enhanced performance is attributed to facilitated Li-ion reactions with the MnSi alloy phase and the formation of a structurally reinforced electroconductive matrix of rGO nanosheets. The ternary nanocomposite design paradigm presented in this study can be exploited for the development of high-capacity and long-life anode materials for versatile LIB applications.

Thermodynamics of concentrated electrolyte mixtures and the prediction of mineral solubilities to high temperatures for mixtures in the system Na-K-Mg-Cl-SO 4-OH-H 2O

NASA Astrophysics Data System (ADS)

Pabalan, Roberto T.; Pitzer, Kenneth S.

1987-09-01

Mineral solubilities in binary and ternary electrolyte mixtures in the system Na-K-Mg-Cl-SO 4-OH-H 2O are calculated to high temperatures using available thermodynamic data for solids and for aqueous electrolyte solutions. Activity and osmotic coefficients are derived from the ion-interaction model of Pitzer (1973, 1979) and co-workers, the parameters of which are evaluated from experimentally determined solution properties or from solubility data in binary and ternary mixtures. Excellent to good agreement with experimental solubilities for binary and ternary mixtures indicate that the model can be successfully used to predict mineral-solution equilibria to high temperatures. Although there are currently no theoretical forms for the temperature dependencies of the various model parameters, the solubility data in ternary mixtures can be adequately represented by constant values of the mixing term θ ij and values of ψ ijk which are either constant or have a simple temperature dependence. Since no additional parameters are needed to describe the thermodynamic properties of more complex electrolyte mixtures, the calculations can be extended to equilibrium studies relevant to natural systems. Examples of predicted solubilities are given for the quaternary system NaCl-KCl-MgCl 2-H 2O.

The transcriptional coactivator Maml1 is required for Notch2-mediated marginal zone B-cell development

PubMed Central

Maillard, Ivan; Nakamura, Makoto; Pear, Warren S.; Griffin, James D.

2007-01-01

Signaling mediated by various Notch receptors and their ligands regulates diverse biological processes, including lymphoid cell fate decisions. Notch1 is required during T-cell development, while Notch2 and the Notch ligand Delta-like1 control marginal zone B (MZB) cell development. We previously determined that Mastermind-like (MAML) transcriptional coactivators are required for Notchinduced transcription by forming ternary nuclear complexes with Notch and the transcription factor CSL. The 3 MAML family members (MAML1-MAML3) are collectively essential for Notch activity in vivo, but whether individual MAMLs contribute to the specificity of Notch functions is unknown. Here, we addressed this question by studying lymphopoiesis in the absence of the Maml1 gene. Since Maml1−/− mice suffered perinatal lethality, hematopoietic chimeras were generated with Maml1−/−, Maml1+/−, or wild-type fetal liver progenitors. Maml1 deficiency minimally affected T-cell development, but was required for the development of MZB cells, similar to the phenotype of Notch2 deficiency. Moreover, the number of MZB cells correlated with Maml1 gene dosage. Since all 3 Maml genes were expressed in MZB cells and their precursors, these results suggest that Maml1 is specifically required for Notch2 signaling in MZB cells. PMID:17699740

Substrate-induced stable enzyme-inhibitor complex formation allows tight binding of novel 2-aminopyrimidin-4(3H)-ones to drug-resistant HIV-1 reverse transcriptase mutants.

PubMed

Samuele, Alberta; Facchini, Marcella; Rotili, Dante; Mai, Antonello; Artico, Marino; Armand-Ugón, Mercedes; Esté, José A; Maga, Giovanni

2008-09-01

We recently reported the synthesis and biological evaluation of a novel series of 5-alkyl-2-(N,N-disubstituted)amino-6-(2,6-difluorophenylalkyl)-3,4-dihydropyrimidin-4(3H)-ones (F(2)-N,N-DABOs). These compounds are highly active against both wild-type HIV-1 and the K103N, Y181C, and Y188L mutant strains. Herein we present novel 6-(2-chloro-6-fluorophenylalkyl)-N,N-DABO (2-Cl-6-F-N,N-DABO) derivatives and investigate the molecular basis for their high-affinity binding to HIV-1 reverse transcriptase (RT). Our results show that the new compounds display higher association rates than the difluoro derivatives toward wild-type HIV-1 RT or drug-resistant RT mutant forms. We also show that they preferentially associate to either the free enzyme or the enzyme-nucleic acid binary complex, and that this binding is stabilized upon formation of the ternary complex between HIV-1 RT and both the nucleic acid and nucleotide substrates. Interestingly, one compound showed dissociation rates from the ternary complex with RT mutants K103N and Y181I 10-20-fold slower than from the corresponding complex with wild-type RT.

The structures of the horseradish peroxidase C-ferulic acid complex and the ternary complex with cyanide suggest how peroxidases oxidize small phenolic substrates.

PubMed

Henriksen, A; Smith, A T; Gajhede, M

1999-12-03

We have solved the x-ray structures of the binary horseradish peroxidase C-ferulic acid complex and the ternary horseradish peroxidase C-cyanide-ferulic acid complex to 2.0 and 1.45 A, respectively. Ferulic acid is a naturally occurring phenolic compound found in the plant cell wall and is an in vivo substrate for plant peroxidases. The x-ray structures demonstrate the flexibility and dynamic character of the aromatic donor binding site in horseradish peroxidase and emphasize the role of the distal arginine (Arg(38)) in both substrate oxidation and ligand binding. Arg(38) hydrogen bonds to bound cyanide, thereby contributing to the stabilization of the horseradish peroxidase-cyanide complex and suggesting that the distal arginine will be able to contribute with a similar interaction during stabilization of a bound peroxy transition state and subsequent O-O bond cleavage. The catalytic arginine is additionally engaged in an extensive hydrogen bonding network, which also includes the catalytic distal histidine, a water molecule and Pro(139), a proline residue conserved within the plant peroxidase superfamily. Based on the observed hydrogen bonding network and previous spectroscopic and kinetic work, a general mechanism of peroxidase substrate oxidation is proposed.

The Kinetic Mechanism of Phenylalanine Hydroxylase: Intrinsic Binding and Rate Constants from Single Turnover Experiments†

PubMed Central

Roberts, Kenneth M.; Pavon, Jorge Alex; Fitzpatrick, Paul F.

2013-01-01

Phenylalanine hydroxylase (PheH) catalyzes the key step in the catabolism of dietary phenylalanine, its hydroxylation to tyrosine using tetrahydrobiopterin (BH4) and O2. A complete kinetic mechanism for PheH was determined by global analysis of single turnover data in the reaction of PheHΔ117, a truncated form of the enzyme lacking the N-terminal regulatory domain. Formation of the productive PheHΔ117-BH4-phenylalanine complex begins with the rapid binding of BH4 (Kd = 65 µM). Subsequent addition of phenylalanine to the binary complex to form the productive ternary complex (Kd = 130 µM) is approximately ten-fold slower. Both substrates can also bind to the free enzyme to form inhibitory binary complexes. O2 rapidly binds to the productive ternary complex; this is followed by formation of an unidentified intermediate, detectable as a decrease in absorbance at 340 nm, with a rate constant of 140 s−1. Formation of the 4a-hydroxypterin and Fe(IV)O intermediates is ten-fold slower and is followed by the rapid hydroxylation of the amino acid. Product release is the rate-determining step and largely determines kcat. Similar reactions using 6-methyltetrahydropterin indicate a preference for the physiological pterin during hydroxylation. PMID:23327364

Adsorption of Selenium and Strontium on Goethite: EXAFS Study and Surface Complexation Modeling of the Ternary Systems.

PubMed

Nie, Zhe; Finck, Nicolas; Heberling, Frank; Pruessmann, Tim; Liu, Chunli; Lützenkirchen, Johannes

2017-04-04

Knowledge of the geochemical behavior of selenium and strontium is critical for the safe disposal of radioactive wastes. Goethite, as one of the most thermodynamically stable and commonly occurring natural iron oxy-hydroxides, promisingly retains these elements. This work comprehensively studies the adsorption of Se(IV) and Sr(II) on goethite. Starting from electrokinetic measurements, the binary and ternary adsorption systems are investigated and systematically compared via batch experiments, EXAFS analysis, and CD-MUSIC modeling. Se(IV) forms bidentate inner-sphere surface complexes, while Sr(II) is assumed to form outer-sphere complexes at low and intermediate pH and inner-sphere complexes at high pH. Instead of a direct interaction between Se(IV) and Sr(II), our results indicate an electrostatically driven mutual enhancement of adsorption. Adsorption of Sr(II) is promoted by an average factor of 5 within the typical groundwater pH range from 6 to 8 for the concentration range studied here. However, the interaction between Se(IV) and Sr(II) at the surface is two-sided, Se(IV) promotes Sr(II) outer-sphere adsorption, but competes for inner-sphere adsorption sites at high pH. The complexity of surfaces is highlighted by the inability of adsorption models to predict isoelectric points without additional constraints.

Crystal structures of palladium(II) ternary complexes of 5-x-2-aminobenzoic acid with 1,10-phenanthroline and their interaction with calf thymus DNA (where X=Cl, Br and I).

PubMed

Wang, Yue; Okabe, Nobuo; Odoko, Mamiko

2005-10-01

The crystal structures of a series of three palladium(II) ternary complexes of 5-halogeno-2-aminobenzoic acid (5-X-AB, where X=Cl, Br and I) with 1,10-phenanthroline [Pd(5-Cl-AB)(phen)] (1), [Pd(5-Br-AB)(phen)] (2) and [Pd(5-I-AB)(phen)] (3) have been determined, and their coordination geometries and the crystal architecture characterized. All of the complexes are an isostructure in which each Pd(II) atom has basically similar square planar coordination geometry. The substitute halogen group at 5-position of AB plays an important role in producing the coordination bonds of the carboxylate and amino groups in which the carboxylate O atom and the amino N atom act as the negative monodentate ligand atoms. The coordination bond distances of O-Pd increase in the order 1<2<3, while those of N-Pd decrease in the same order. The binding of the complexes to the calf thymus DNA has also been studied by the fluorescence method. Each of the complexes shows high binding propensity to DNA which can be reflected as the relative order 1<2<3.

Son of sevenless directly links the Robo receptor to rac activation to control axon repulsion at the midline.

PubMed

Yang, Long; Bashaw, Greg J

2006-11-22

Son of sevenless (Sos) is a dual specificity guanine nucleotide exchange factor (GEF) that regulates both Ras and Rho family GTPases and thus is uniquely poised to integrate signals that affect both gene expression and cytoskeletal reorganization. Here, using genetics, biochemistry, and cell biology, we demonstrate that Sos is recruited to the plasma membrane, where it forms a ternary complex with the Roundabout receptor and the SH3-SH2 adaptor protein Dreadlocks (Dock) to regulate Rac-dependent cytoskeletal rearrangement in response to the Slit ligand. Intriguingly, the Ras and Rac-GEF activities of Sos can be uncoupled during Robo-mediated axon repulsion; Sos axon guidance function depends on its Rac-GEF activity, but not its Ras-GEF activity. These results provide in vivo evidence that the Ras and RhoGEF domains of Sos are separable signaling modules and support a model in which Robo recruits Sos to the membrane via Dock to activate Rac during midline repulsion.

Zyxin-Siah2–Lats2 axis mediates cooperation between Hippo and TGF-β signalling pathways

PubMed Central

Ma, Biao; Cheng, Hongcheng; Gao, Ruize; Mu, Chenglong; Chen, Ling; Wu, Shian; Chen, Quan; Zhu, Yushan

2016-01-01

The evolutionarily conserved Hippo pathway is a regulator that controls organ size, cell growth and tissue homeostasis. Upstream signals of the Hippo pathway have been widely studied, but how microenvironmental factors coordinately regulate this pathway remains unclear. In this study, we identify LIM domain protein Zyxin, as a scaffold protein, that in response to hypoxia and TGF-β stimuli, forms a ternary complex with Lats2 and Siah2 and stabilizes their interaction. This interaction facilitates Lats2 ubiquitination and degradation, Yap dephosphorylation and subsequently activation. We show that Zyxin is required for TGF-β and hypoxia-induced Lats2 downregulation and deactivation of Hippo signalling in MDA-MB-231 cells. Depletion of Zyxin impairs the capability of cell migration, proliferation and tumourigenesis in a xenograft model. Zyxin is upregulated in human breast cancer and positively correlates with histological stages and metastasis. Our study demonstrates that Zyxin-Lats2–Siah2 axis may serve as a potential therapeutic target in cancer treatment. PMID:27030211

Rhodanine hydrolysis leads to potent thioenolate mediated metallo-β-lactamase inhibition

NASA Astrophysics Data System (ADS)

Brem, Jürgen; van Berkel, Sander S.; Aik, Weishen; Rydzik, Anna M.; Avison, Matthew B.; Pettinati, Ilaria; Umland, Klaus-Daniel; Kawamura, Akane; Spencer, James; Claridge, Timothy D. W.; McDonough, Michael A.; Schofield, Christopher J.

2014-12-01

The use of β-lactam antibiotics is compromised by resistance, which is provided by β-lactamases belonging to both metallo (MBL)- and serine (SBL)-β-lactamase subfamilies. The rhodanines are one of very few compound classes that inhibit penicillin-binding proteins (PBPs), SBLs and, as recently reported, MBLs. Here, we describe crystallographic analyses of the mechanism of inhibition of the clinically relevant VIM-2 MBL by a rhodanine, which reveal that the rhodanine ring undergoes hydrolysis to give a thioenolate. The thioenolate is found to bind via di-zinc chelation, mimicking the binding of intermediates in β-lactam hydrolysis. Crystallization of VIM-2 in the presence of the intact rhodanine led to observation of a ternary complex of MBL, a thioenolate fragment and rhodanine. The crystallographic observations are supported by kinetic and biophysical studies, including 19F NMR analyses, which reveal the rhodanine-derived thioenolate to be a potent broad-spectrum MBL inhibitor and a lead structure for the development of new types of clinically useful MBL inhibitors.

Effect of seven Indian plant extracts on Fenton reaction-mediated damage to DNA constituents.

PubMed

Kar, Indrani; Chattopadhyaya, Rajagopal

2017-11-01

The influences of substoichiometric amounts of seven plant extracts in the Fenton reaction-mediated damage to deoxynucleosides, deoxynucleoside monophosphates, deoxynucleoside triphosphates, and supercoiled plasmid DNA were studied to rationalize anticancer properties reported in some of these extracts. Extracts from Acacia catechu, Emblica officinalis, Spondias dulcis, Terminalia belerica, Terminalia chebula, as well as gallic acid, epicatechin, chebulagic acid and chebulinic acid enhance the extent of damage in Fenton reactions with all monomeric substrates but protect supercoiled plasmid DNA, compared to standard Fenton reactions. The damage to pyrimidine nucleosides/nucleotides is enhanced by these extracts and compounds to a greater extent than for purine ones in a concentration dependent manner. Dolichos biflorus and Hemidesmus indicus extracts generally do not show this enhancement for the monomeric substrates though they protect plasmid DNA. Compared to standard Fenton reactions for deoxynucleosides with ethanol, the presence of these five plant extracts render ethanol scavenging less effective as the radical is generated in the vicinity of the target. Since substoichiometric amounts of these extracts and the four compounds produce this effect, a catalytic mechanism involving the presence of a ternary complex of the nucleoside/nucleotide substrate, a plant compound and the hydroxyl radical is proposed. Such a mechanism cannot operate for plasmid DNA as the planar rings in the extract compounds cannot stack with the duplex DNA bases. These plant extracts, by enhancing Fenton reaction-mediated damage to deoxynucleoside triphosphates, slow down DNA replication in rapidly dividing cancer cells, thus contributing to their anticancer properties.

ON THE REACTION OF COMPONENETS IN MeNO$sub 3$-UO$sub 2$(NO$sub 3$)$sub 2$- H$sub 2$O TYPE SYSTEMS (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yakimov, M.A.; Nosova, N.F.; Degtyarev, A.Ya.

1963-01-01

Solubility in ternary systems TlNO/sub 3/--UO/sub 2/(NO/sub 3/)/sub 2/-- H/sub 2/ O and CsNO/sub 3/--UO/sub 2/(NO/sub 3/)/sub 2/--H/sub 2/O at 0 to 25 c- C was studi ed by the isothermal method. The first system did not form solid phase compounds; the second system formed two compounds Cs/sub 2/UO/ sub 2/(NO/sub 3/)/sub 4/ and CsUO/sub 2/(NO/sub 3/)/sub 3/ at 25 c- and of water vapor pressure over the systems at 25 c- showed that water activity in the ternary systems at certain concentrations does not exceed the water activity in binary uranyl nitratewater system (at identical uranyl nitrate concentrations) confirmingmore » the observed complex formation in the solution. The mechanism of complex formation was analyzed and expanded for alkali metal - metal salt-complexing agent water systems. (R.V.J.)« less

Human topoisomerase I poisoning: docking protoberberines into a structure-based binding site model

NASA Astrophysics Data System (ADS)

Kettmann, Viktor; Košt'álová, Daniela; Höltje, Hans-Dieter

2004-12-01

Using the X-ray crystal structure of the human topoisomerase I (top1) - DNA cleavable complex and the Sybyl software package, we have developed a general model for the ternary cleavable complex formed with four protoberberine alkaloids differing in the substitution on the terminal phenyl rings and covering a broad range of the top1-poisoning activities. This model has the drug intercalated with its planar chromophore between the -1 and +1 base pairs flanking the cleavage site, with the nonplanar portion pointing into the minor groove. The ternary complexes were geometry-optimized and relative interaction energies, computed by using the Tripos force field, were found to rank in correct order the biological potency of the compounds; in addition, the model is also consistent with the top1-poisoning inactivity of berberine, a major prototype of the protoberberine alkaloids. The model might serve as a rational basis for elaboration of the most active compound as a lead structure, in order to develop more potent top1 poisons as next generation anti-cancer drugs.

Binary and ternary copper(II) complexes of a new Schiff base ligand derived from 4-acetyl-5,6-diphenyl-3(2H)-pyridazinone: Synthesis, spectral, thermal, antimicrobial and antitumor studies

NASA Astrophysics Data System (ADS)

Shebl, Magdy; Adly, Omima M. I.; Abdelrhman, Ebtesam M.; El-Shetary, B. A.

2017-10-01

A new Schiff base ligand was synthesized by the reaction of 4-acetyl-5,6-diphenyl-3(2H)-pyridazinone with ethylenediamine. A series of binary copper(II) Schiff base complexes have been synthesized by using various copper(II) salts; AcO-, NO3-, ClO4-, Cl- and Br-. Ternary complexes were synthesized by using auxiliary ligands (L‧) [N,O-donor; 8-hydroxyquinoline and glycine or N,N-donor; 1,10-phenanthroline, bipyridyl and 2-aminopyridine]. The structures of the Schiff base and its complexes were characterized by elemental and thermal analyses, IR, electronic, mass, 1H NMR and ESR spectra in addition to conductivity and magnetic susceptibility measurements. The obtained complexes include neutral binuclear complexes as well as neutral and cationic mononuclear complexes according to the anion used and the experimental conditions. The ESR spin Hamiltonian parameters of some complexes were calculated and discussed. The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. Kinetic parameters (Ea, A, ΔH, ΔS and ΔG) of the thermal decomposition stages were evaluated using Coats-Redfern equations. The antimicrobial activity of the Schiff base and its complexes was screened against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus). The antitumor activity of the Schiff base and some of its Cu(II) complexes was investigated against HepG-2 cell line.

Understanding the vapor-liquid-solid growth and composition of ternary III-V nanowires and nanowire heterostructures

NASA Astrophysics Data System (ADS)

Dubrovskii, V. G.

2017-11-01

Based on the recent achievements in vapor-liquid-solid (VLS) synthesis, characterization and modeling of ternary III-V nanowires and axial heterostructures within such nanowires, we try to understand the major trends in their compositional evolution from a general theoretical perspective. Clearly, the VLS growth of ternary materials is much more complex than in standard vapor-solid epitaxy techniques, and even maintaining the necessary control over the composition of steady-state ternary nanowires is far from straightforward. On the other hand, VLS nanowires offer otherwise unattainable material combinations without introducing structural defects and hence are very promising for next-generation optoelectronic devices, in particular those integrated with a silicon electronic platform. In this review, we consider two main problems. First, we show how and by means of which parameters the steady-state composition of Au-catalyzed or self-catalyzed ternary III-V nanowires can be tuned to a desired value and why it is generally different from the vapor composition. Second, we present some experimental data and modeling results for the interfacial abruptness across axial nanowire heterostructures, both in Au-catalyzed and self-catalyzed VLS growth methods. Refined modeling allows us to formulate some general growth recipes for suppressing the unwanted reservoir effect in the droplet and sharpening the nanowire heterojunctions. We consider and refine two approaches developed to date, namely the regular crystallization model for a liquid alloy with a critical size of only one III-V pair at high supersaturations or classical binary nucleation theory with a macroscopic critical nucleus at modest supersaturations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Yirui; Scheuermann, Thomas H.; Partch, Carrie L.

The hypoxia-inducible factor complex (HIF-α·aryl hydrocarbon receptor nuclear translocator (ARNT)) requires association with several transcription coactivators for a successful cellular response to hypoxic stress. In addition to the conventional global transcription coactivator CREB-binding protein/p300 (CBP/p300) that binds to the HIF-α transactivation domain, a new group of transcription coactivators called the coiled-coil coactivators (CCCs) interact directly with the second PER-ARNT-SIM (PAS) domain of ARNT (ARNT PAS-B). These less studied transcription coactivators play essential roles in the HIF-dependent hypoxia response, and CCC misregulation is associated with several forms of cancer. To better understand CCC protein recruitment by the heterodimeric HIF transcription factor,more » we used x-ray crystallography, NMR spectroscopy, and biochemical methods to investigate the structure of the ARNT PAS-B domain in complex with the C-terminal fragment of a coiled-coil coactivator protein, transforming acidic coiled-coil coactivator 3 (TACC3). We found that the HIF-2α PAS-B domain also directly interacts with TACC3, motivating an NMR data-derived model suggesting a means by which TACC3 could form a ternary complex with HIF-2α PAS-B and ARNT PAS-B via β-sheet/coiled-coil interactions. Furthermore, these findings suggest that TACC3 could be recruited as a bridge to cooperatively mediate between the HIF-2α PAS-B·ARNT PAS-B complex, thereby participating more directly in HIF-dependent gene transcription than previously anticipated.« less

Interactions of diamines with adenosine-5'-triphosphate (ATP) in the systems including copper(II) ions.

PubMed

Bregier-Jarzebowska, R; Gasowska, A; Hoffmann, S K; Lomozik, L

2016-09-01

Interactions were studied in the systems ATP/tn and ATP/Put (tn=1,3-diaminopropane, Put=putrescine) whereas the complexation reactions in ternary systems Cu(II)/ATP/tn and Cu(II)/ATP/Put. Results of the potentiometric and spectroscopic studies evidenced the formation of adducts of the type (ATP)H x (PA), where PA=diamine. The thermodynamic stability of the complexes and the mode of interactions were determined. On the basis of analysis of changes in the positions of NMR signals, in the pH range of (ATP)H 3 (Put) formation, the preferred centres of the interaction between ATP and Put are the endocyclic nitrogen atoms from the nucleotide. On the other hand, the shorter diamine tn in the entire pH range reacts with the phosphate groups from ATP. The positive centres of noncovalent interactions are the protonated NH x + groups from amines. In both complexes Cu(ATP)H 2 (tn) and Cu(ATP)H 3 (Put) formed in ternary systems at pH<6.5, the amines are in the outer sphere of coordination with the noncovalent interaction with anchoring Cu(ATP). Only the phosphate groups from the nucleotide take part in metalation. At higher pH in the range of Cu(ATP)(PA) complex formation, significant differences in the reactions of the two amines appear. The shorter one (tn) binds Cu(II) ions with two nitrogen atoms, while putrescine coordinates in the monofunctional mode, which is undoubtedly related to the differences in lengths of methylene chain. This explains the considerable differences in the stability of Cu(ATP)(tn) and Cu(ATP)(Put). In both complexes the nucleotide is coordinated through phosphate groups. As a result of noncovalent interactions ATP forms molecular complexes with 1,3-diaminopropane and 1,4-diaminobutane (putrescine). Significant differences in the mode of interactions between the two diamines were observed in ATP/diamine binary systems and in ternary systems Cu(II)/ATP/diamine, at high pH. Copyright © 2016 Elsevier Inc. All rights reserved.

Phosphate and phytate adsorption and precipitation on ferrihydrite surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xiaoming; Hu, Yongfeng; Tang, Yadong

Phosphorous (P) sorption on mineral surfaces largely controls P mobility and bioavailability, hence its pollution potential, but the sorption speciation and mechanism remain poorly understood. In this study, we have identified and quantified the speciation of both phosphate and phytate sorbed on ferrihydrite with various P loadings at pH 3–8 using differential atomic pair distribution function (d-PDF) analysis, synchrotron-based X-ray diffraction (XRD), and P and Fe K-edge X-ray absorption near edge structure (XANES) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. With increasing P sorption loading for both phosphate and phytate, the sorption mechanism transits from bidentate-binuclear surface complexation tomore » unidentified ternary complexation and to precipitation of amorphous FePO 4 and amorphous Fe-phytate. At a given P sorption loading, phosphate precipitates more readily than phytate. Both phosphate and phytate promote ferrihydrite dissolution with phytate more intensively, but the dissolved FeIII concentration in the bulk solution is low because the majority of the released Fe III precipitate with the anions. Results also show that amorphous FePO 4 and amorphous Fe-phytate have similar PO 4 local coordination environment. In conclusion, these new insights into the P surface complexation and precipitation, and the ligand-promoted dissolution behavior improve our understanding of P fate in soils, aquatic environment and water treatment systems as mediated by mineral-water interfacial reactions.« less

Phosphate and phytate adsorption and precipitation on ferrihydrite surfaces

DOE PAGES

Wang, Xiaoming; Hu, Yongfeng; Tang, Yadong; ...

2017-09-26

Phosphorous (P) sorption on mineral surfaces largely controls P mobility and bioavailability, hence its pollution potential, but the sorption speciation and mechanism remain poorly understood. In this study, we have identified and quantified the speciation of both phosphate and phytate sorbed on ferrihydrite with various P loadings at pH 3–8 using differential atomic pair distribution function (d-PDF) analysis, synchrotron-based X-ray diffraction (XRD), and P and Fe K-edge X-ray absorption near edge structure (XANES) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. With increasing P sorption loading for both phosphate and phytate, the sorption mechanism transits from bidentate-binuclear surface complexation tomore » unidentified ternary complexation and to precipitation of amorphous FePO 4 and amorphous Fe-phytate. At a given P sorption loading, phosphate precipitates more readily than phytate. Both phosphate and phytate promote ferrihydrite dissolution with phytate more intensively, but the dissolved FeIII concentration in the bulk solution is low because the majority of the released Fe III precipitate with the anions. Results also show that amorphous FePO 4 and amorphous Fe-phytate have similar PO 4 local coordination environment. In conclusion, these new insights into the P surface complexation and precipitation, and the ligand-promoted dissolution behavior improve our understanding of P fate in soils, aquatic environment and water treatment systems as mediated by mineral-water interfacial reactions.« less

Mammalian polo-like kinase 1-dependent regulation of the PBIP1-CENP-Q complex at kinetochores.

PubMed

Kang, Young H; Park, Chi Hoon; Kim, Tae-Sung; Soung, Nak-Kyun; Bang, Jeong K; Kim, Bo Y; Park, Jung-Eun; Lee, Kyung S

2011-06-03

Mammalian polo-like kinase 1 (Plk1) plays a pivotal role during M-phase progression. Plk1 localizes to specific subcellular structures through the targeting activity of the C-terminal polo-box domain (PBD). Disruption of the PBD function results in improper bipolar spindle formation, chromosome missegregation, and cytokinesis defect that ultimately lead to the generation of aneuploidy. It has been shown that Plk1 recruits itself to centromeres by phosphorylating and binding to a centromere scaffold, PBIP1 (also called MLF1IP and CENP-U[50]) through its PBD. However, how PBIP1 itself is targeted to centromeres and what roles it plays in the regulation of Plk1-dependent mitotic events remain unknown. Here, we demonstrated that PBIP1 directly interacts with CENP-Q, and this interaction was mutually required not only for their stability but also for their centromere localization. Plk1 did not appear to interact with CENP-Q directly. However, Plk1 formed a ternary complex with PBIP1 and CENP-Q through a self-generated p-T78 motif on PBIP1. This complex formation was central for Plk1-dependent phosphorylation of PBIP1-bound CENP-Q and delocalization of the PBIP1-CENP-Q complex from mitotic centromeres. This study reveals a unique mechanism of how PBIP1 mediates Plk1-dependent phosphorylation event onto a third protein, and provides new insights into the mechanism of how Plk1 and its recruitment scaffold, PBIP1-CENP-Q complex, are localized to and delocalized from centromeres.

Mammalian Polo-like Kinase 1-dependent Regulation of the PBIP1-CENP-Q Complex at Kinetochores*

PubMed Central

Kang, Young H.; Park, Chi Hoon; Kim, Tae-Sung; Soung, Nak-Kyun; Bang, Jeong K.; Kim, Bo Y.; Park, Jung-Eun; Lee, Kyung S.

2011-01-01

Mammalian polo-like kinase 1 (Plk1) plays a pivotal role during M-phase progression. Plk1 localizes to specific subcellular structures through the targeting activity of the C-terminal polo-box domain (PBD). Disruption of the PBD function results in improper bipolar spindle formation, chromosome missegregation, and cytokinesis defect that ultimately lead to the generation of aneuploidy. It has been shown that Plk1 recruits itself to centromeres by phosphorylating and binding to a centromere scaffold, PBIP1 (also called MLF1IP and CENP-U[50]) through its PBD. However, how PBIP1 itself is targeted to centromeres and what roles it plays in the regulation of Plk1-dependent mitotic events remain unknown. Here, we demonstrated that PBIP1 directly interacts with CENP-Q, and this interaction was mutually required not only for their stability but also for their centromere localization. Plk1 did not appear to interact with CENP-Q directly. However, Plk1 formed a ternary complex with PBIP1 and CENP-Q through a self-generated p-T78 motif on PBIP1. This complex formation was central for Plk1-dependent phosphorylation of PBIP1-bound CENP-Q and delocalization of the PBIP1-CENP-Q complex from mitotic centromeres. This study reveals a unique mechanism of how PBIP1 mediates Plk1-dependent phosphorylation event onto a third protein, and provides new insights into the mechanism of how Plk1 and its recruitment scaffold, PBIP1-CENP-Q complex, are localized to and delocalized from centromeres. PMID:21454580

IGF-1, IGFBP-3 and ALS in adult patients with chronic kidney disease.

PubMed

Lepenies, Julia; Wu, Zida; Stewart, Paul M; Strasburger, Christian J; Quinkler, Marcus

2010-04-01

Insulin-like growth factor I (IGF-1) is for the most part bound in a ternary complex with IGF-binding protein-3 (IGFBP-3) and acid-labile subunit (ALS). This ternary complex is a storage form of IGF-1 in blood and passes not through the renal glomerulus. Little information is available in regard to the components of the ternary complex in adult renal disease. To investigate levels of serum IGF-1, IGFBP-3 and ALS in relation to renal function and extent of proteinuria. We measured IGF-1, IGFBP-3 and ALS concentrations in 137 patients who were investigated due to proteinuria and/or haematuria and/or renal impairment. The patients received renal biopsies and the histological diagnosis was documented. Urinary albumin excretion and relevant clinical parameter were evaluated. IGF-1 showed a highly positive correlation to IGFBP-3 and ALS, and the latter to IGFBP-3. IGF-1, IGFBP-3 and ALS decreased with increasing age. IGF-1 and IGFBP-3 showed no significant change depending on the creatinine clearance. However, ALS decreased with decreasing renal function. In patients with heavy proteinuria ALS levels, but not IGF-1 and IGFBP-3 levels, decreased significantly. Patients with chronic ischaemic renal damage and diabetic glomerulopathy showed higher IGF-1 and IGFBP-3 levels compared to patients with thin glomerular basement membrane disease despite their older age. IGF-1 and IGFBP-3 levels seem to be independent of renal function and severity of proteinuria. However, ALS levels are altered in renal failure and nephrotic syndrome, which may be due to increased renal loss or diminished hepatic production or both. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Folding of thyroglobulin in the calnexin/calreticulin pathway and its alteration by loss of Ca2+ from the endoplasmic reticulum.

PubMed Central

Di Jeso, Bruno; Ulianich, Luca; Pacifico, Francesco; Leonardi, Antonio; Vito, Pasquale; Consiglio, Eduardo; Formisano, Silvestro; Arvan, Peter

2003-01-01

During its initial folding in the endoplasmic reticulum (ER), newly synthesized thyroglobulin (Tg) is known to interact with calnexin and other ER molecular chaperones, but its interaction with calreticulin has not been examined previously. In the present study, we have investigated the interactions of endogenous Tg with calreticulin and with several other ER chaperones. We find that, in FRTL-5 and PC-Cl3 cells, calnexin and calreticulin interact with newly synthesized Tg in a carbohydrate-dependent manner, with largely overlapping kinetics that are concomitant with the maturation of Tg intrachain disulphide bonds, preceding Tg dimerization and exit from the ER. Calreticulin co-precipitates more newly synthesized Tg than does calnexin; however, using two different experimental approaches, calnexin and calreticulin were found in ternary complexes with Tg, making this the first endogenous protein reported in ternary complexes with calnexin and calreticulin in the ER of live cells. Depletion of Ca(2+) from the ER elicited by thapsigargin (a specific inhibitor of ER Ca(2+)-ATPases) results in retention of Tg in this organelle. Interestingly, thapsigargin treatment induces the premature exit of Tg from the calnexin/calreticulin cycle, while stabilizing and prolonging interactions of Tg with BiP (immunoglobulin heavy chain binding protein) and GRP94 (glucose-regulated protein 94), two chaperones whose binding is not carbohydrate-dependent. Our results suggest that calnexin and calreticulin, acting in ternary complexes with a large glycoprotein substrate such as Tg, might be engaged in the folding of distinct domains, and indicate that lumenal Ca(2+) strongly influences the folding of exportable glycoproteins, in part by regulating the balance of substrate binding to different molecular chaperone systems within the ER. PMID:12401114

Green fluorescence protein-based content-mixing assay of SNARE-driven membrane fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heo, Paul; Kong, Byoungjae; Jung, Young-Hun

Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins mediate intracellular membrane fusion by forming a ternary SNARE complex. A minimalist approach utilizing proteoliposomes with reconstituted SNARE proteins yielded a wealth of information pinpointing the molecular mechanism of SNARE-mediated fusion and its regulation by accessory proteins. Two important attributes of a membrane fusion are lipid-mixing and the formation of an aqueous passage between apposing membranes. These two attributes are typically observed by using various fluorescent dyes. Currently available in vitro assay systems for observing fusion pore opening have several weaknesses such as cargo-bleeding, incomplete removal of unencapsulated dyes, and inadequate information regardingmore » the size of the fusion pore, limiting measurements of the final stage of membrane fusion. In the present study, we used a biotinylated green fluorescence protein and streptavidin conjugated with Dylight 594 (DyStrp) as a Föster resonance energy transfer (FRET) donor and acceptor, respectively. This FRET pair encapsulated in each v-vesicle containing synaptobrevin and t-vesicle containing a binary acceptor complex of syntaxin 1a and synaptosomal-associated protein 25 revealed the opening of a large fusion pore of more than 5 nm, without the unwanted signals from unencapsulated dyes or leakage. This system enabled determination of the stoichiometry of the merging vesicles because the FRET efficiency of the FRET pair depended on the molar ratio between dyes. Here, we report a robust and informative assay for SNARE-mediated fusion pore opening. - Highlights: • SNARE proteins drive membrane fusion and open a pore for cargo release. • Biotinylated GFP and DyStrp was used as the reporter pair of fusion pore opening. • Procedure for efficient SNARE reconstitution and reporter encapsulation was established. • The FRET pair reported opening of a large fusion pore bigger than 5 nm. • The assay was robust and provided information of stoichiometry of vesicle fusion.« less

Evidence of insulin-like growth factor binding protein-3 proteolysis during growth hormone stimulation testing.

PubMed

Nwosu, Benjamin U; Soyka, Leslie A; Angelescu, Amanda; Lee, Mary M

2011-01-01

The ternary complex is composed of insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-3 and acid labile subunit (ALS). Growth hormone (GH) promotes IGFBP-3 proteolysis to release free IGF-I, ALS, and IGFBP-3 fragments. Our aim was to determine whether elevated GH levels during GH stimulation testing would trigger IGFBP-3 proteolysis. This prospective study of 10 short prepubertal children (height standard deviation score -2.37 +/- 0.31) used arginine and GH releasing hormone stimulation to study dynamic changes in the ternary complex moieties. IGFBP-3 was measured in two assays: a radioimmunoassay (RIA) that detects both cleaved and intact IGFBP-3; and an immunochemiluminescence assay (ICMA) that detects only intact IGFBP-3. IGFBP-3 measured by RIA increased by 19% (p < 0.05), while IGFBP-3 measured by ICMA did not significantly increase (6.1%). The significant increase in IGFBP-3 measured by RIA, but not ICMA, provides evidence of IGFBP-3 proteolysis during acute GH stimulation.

Surface Segregation in Multicomponent Systems: Modeling of Surface Alloys and Alloy Surfaces

NASA Technical Reports Server (NTRS)

Bozzolo, Guillermo; Ferrante, John; Noebe, Ronald D.; Good, Brian; Honecy, Frank S.; Abel, Phillip

1999-01-01

The study of surface segregation, although of great technological importance, has been largely restricted to experimental work due to limitations associated with theoretical methods. However, recent improvements in both first-particle and semi-empirical methods are opening, the doors to an array of new possibilities for surface scientists. We apply one of these techniques, the Bozzolo, Ferrante and Smith (BFS) method for alloys, which is particularly suitable for complex systems, to several aspects of the computational modeling of surfaces and segregation, including alloy surface segregation, structure and composition of alloy surfaces, and the formation of surface alloys. We conclude with the study of complex NiAl-based binary, ternary and quaternary thin films (with Ti, Cr and Cu additions to NiAl). Differences and similarities between bulk and surface compositions are discussed, illustrated by the results of Monte Carlo simulations. For some binary and ternary cases, the theoretical predictions are compared to experimental results, highlighting the accuracy and value of this developing theoretical tool.

Structure of tropinone reductase-II complexed with NADP+ and pseudotropine at 1.9 A resolution: implication for stereospecific substrate binding and catalysis.

PubMed

Yamashita, A; Kato, H; Wakatsuki, S; Tomizaki, T; Nakatsu, T; Nakajima, K; Hashimoto, T; Yamada, Y; Oda, J

1999-06-15

Tropinone reductase-II (TR-II) catalyzes the NADPH-dependent reduction of the carbonyl group of tropinone to a beta-hydroxyl group. The crystal structure of TR-II complexed with NADP+ and pseudotropine (psi-tropine) has been determined at 1.9 A resolution. A seven-residue peptide near the active site, disordered in the unliganded structure, is fixed in the ternary complex by participation of the cofactor and substrate binding. The psi-tropine molecule is bound in an orientation which satisfies the product configuration and the stereochemical arrangement toward the cofactor. The substrate binding site displays a complementarity to the bound substrate (psi-tropine) in its correct orientation. In addition, electrostatic interactions between the substrate and Glu156 seem to specify the binding position and orientation of the substrate. A comparison between the active sites in TR-II and TR-I shows that they provide different van der Waals surfaces and electrostatic features. These differences likely contribute to the correct binding mode of the substrates, which are in opposite orientations in TR-II and TR-I, and to different reaction stereospecificities. The active site structure in the TR-II ternary complex also suggests that the arrangement of the substrate, cofactor, and catalytic residues is stereoelectronically favorable for the reaction.

Crystal structure of a complete ternary complex of T-cell receptor, peptide-MHC, and CD4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yin, Yiyuan; Wang, Xin Xiang; Mariuzza, Roy A

2012-07-11

Adaptive immunity depends on specific recognition by a T-cell receptor (TCR) of an antigenic peptide bound to a major histocompatibility complex (pMHC) molecule on an antigen-presenting cell (APC). In addition, T-cell activation generally requires binding of this same pMHC to a CD4 or CD8 coreceptor. Here, we report the structure of a complete TCR-pMHC-CD4 ternary complex involving a human autoimmune TCR, a myelin-derived self-peptide bound to HLA-DR4, and CD4. The complex resembles a pointed arch in which TCR and CD4 are each tilted ~65° relative to the T-cell membrane. By precluding direct contacts between TCR and CD4, the structure explainsmore » how TCR and CD4 on the T cell can simultaneously, yet independently, engage the same pMHC on the APC. The structure, in conjunction with previous mutagenesis data, places TCR-associated CD3εγ and CD3εδ subunits, which transmit activation signals to the T cell, inside the TCR-pMHC-CD4 arch, facing CD4. By establishing anchor points for TCR and CD4 on the T-cell membrane, the complex provides a basis for understanding how the CD4 coreceptor focuses TCR on MHC to guide TCR docking on pMHC during thymic T-cell selection.« less

The Phase Behavior of γ-Oryzanol and β-Sitosterol in Edible Oil.

PubMed

Sawalha, Hassan; Venema, Paul; Bot, Arjen; Flöter, Eckhard; Adel, Ruud den; van der Linden, Erik

The phase behavior of binary mixtures of γ-oryzanol and β-sitosterol and ternary mixtures of γ-oryzanol and β-sitosterol in sunflower oil was studied. Binary mixtures of γ-oryzanol and β-sitosterol show double-eutectic behavior. Complex phase behavior with two intermediate mixed solid phases was derived from differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS) data, in which a compound that consists of γ-oryzanol and β-sitosterol molecules at a specific ratio can be formed. SAXS shows that the organization of γ-oryzanol and β-sitosterol in the mixed phases is different from the structure of tubules in ternary systems. Ternary mixtures including sunflower oil do not show a sudden structural transition from the compound to a tubule, but a gradual transition occurs as γ-oryzanol and β-sitosterol are diluted in edible oil. The same behavior is observed when melting binary mixtures of γ-oryzanol and β-sitosterol at higher temperatures. This indicates the feasibility of having an organogelling agent in dynamic exchange between solid and liquid phase, which is an essential feature of triglyceride networks.

Characterization of Ofloxacin Interaction with Mutated (A91V) Quinolone Resistance Determining Region of DNA Gyrase in Mycobacterium Leprae through Computational Simulation.

PubMed

Nisha, J; Shanthi, V

2018-06-01

Mycobacterium leprae, the causal agent of leprosy is non-cultivable in vitro. Thus, the assessment of antibiotic activity against Mycobacterium leprae depends primarily upon the time-consuming mouse footpad system. The GyrA protein of Mycobacterium leprae is the target of the antimycobacterial drug, Ofloxacin. In recent times, the GyrA mutation (A91V) has been found to be resistant to Ofloxacin. This phenomenon has necessitated the development of new, long-acting antimycobacterial compounds. The underlying mechanism of drug resistance is not completely known. Currently, experimentally crystallized GyrA-DNA-OFLX models are not available for highlighting the binding and mechanism of Ofloxacin resistance. Hence, we employed computational approaches to characterize the Ofloxacin interaction with both the native and mutant forms of GyrA complexed with DNA. Binding energy measurements obtained from molecular docking studies highlights hydrogen bond-mediated efficient binding of Ofloxacin to Asp47 in the native GyrA-DNA complex in comparison with that of the mutant GyrA-DNA complex. Further, molecular dynamics studies highlighted the stable binding of Ofloxacin with native GyrA-DNA complex than with the mutant GyrA-DNA complex. This mechanism provided a plausible reason for the reported, reduced effect of Ofloxacin to control leprosy in individuals with the A91V mutation. Our report is the first of its kind wherein the basis for the Ofloxacin drug resistance mechanism has been explored with the help of ternary Mycobacterium leprae complex, GyrA-DNA-OFLX. These structural insights will provide useful information for designing new drugs to target the Ofloxacin-resistant DNA gyrase.

Actin-Sorting Nexin 27 (SNX27)-Retromer Complex Mediates Rapid Parathyroid Hormone Receptor Recycling*

PubMed Central

McGarvey, Jennifer C.; Xiao, Kunhong; Bowman, Shanna L.; Mamonova, Tatyana; Zhang, Qiangmin; Bisello, Alessandro; Sneddon, W. Bruce; Ardura, Juan A.; Jean-Alphonse, Frederic; Vilardaga, Jean-Pierre; Puthenveedu, Manojkumar A.; Friedman, Peter A.

2016-01-01

The G protein-coupled parathyroid hormone receptor (PTHR) regulates mineral-ion homeostasis and bone remodeling. Upon parathyroid hormone (PTH) stimulation, the PTHR internalizes into early endosomes and subsequently traffics to the retromer complex, a sorting platform on early endosomes that promotes recycling of surface receptors. The C terminus of the PTHR contains a type I PDZ ligand that binds PDZ domain-containing proteins. Mass spectrometry identified sorting nexin 27 (SNX27) in isolated endosomes as a PTHR binding partner. PTH treatment enriched endosomal PTHR. SNX27 contains a PDZ domain and serves as a cargo selector for the retromer complex. VPS26, VPS29, and VPS35 retromer subunits were isolated with PTHR in endosomes from cells stimulated with PTH. Molecular dynamics and protein binding studies establish that PTHR and SNX27 interactions depend on the PDZ recognition motif in PTHR and the PDZ domain of SNX27. Depletion of either SNX27 or VPS35 or actin depolymerization decreased the rate of PTHR recycling following agonist stimulation. Mutating the PDZ ligand of PTHR abolished the interaction with SNX27 but did not affect the overall rate of recycling, suggesting that PTHR may directly engage the retromer complex. Coimmunoprecipitation and overlay experiments show that both intact and mutated PTHR bind retromer through the VPS26 protomer and sequentially assemble a ternary complex with PTHR and SNX27. SNX27-independent recycling may involve N-ethylmaleimide-sensitive factor, which binds both PDZ intact and mutant PTHRs. We conclude that PTHR recycles rapidly through at least two pathways, one involving the ASRT complex of actin, SNX27, and retromer and another possibly involving N-ethylmaleimide-sensitive factor. PMID:27008860

Aluminum and Fenton reaction: how can the reaction be modulated by speciation? A computational study using citrate as a test case.

PubMed

Mujika, Jon I; Dalla Torre, Gabriele; Lopez, Xabier

2018-06-13

The pro-oxidant ability of aluminum is behind many of the potential toxic effects of this exogenous element in the human organism. Although the overall process is still far from being understood at the molecular level, the well known ability of aluminum to promote the Fenton reaction is mediated through the formation of stable aluminum-superoxide radical complexes. However, the properties of metal complexes are highly influenced by the speciation of the metal. In this paper, we investigate the effect that speciation could have on the pro-oxidant activity of aluminum. We choose citrate as a test case, because it is the main low-molecular-mass chelator of aluminum in blood serum, forming very stable aluminum-citrate complexes. The influence of citrate in the interaction of aluminum with the superoxide radical is investigated, determining how the formation of aluminum-citrate complexes affects the promotion of the Fenton reaction. The results indicate that citrate increases the stability of the aluminum-superoxide complexes through the formation of ternary compounds, and that the Fenton reaction is even more favorable when aluminum is chelated to citrate. Nevertheless, our results demonstrate that overall, citrate may prevent the pro-oxidant activity of aluminum: on one hand, in an excess of citrate, the formation of 1 : 2 aluminum-citrate complexes is expected. On the other hand, the chelation of iron by citrate makes the reduction of iron thermodynamically unfavorable. In summary, the results suggest that citrate can have both a promotion and protective role, depending on subtle factors, such as initial concentration, non-equilibrium behavior and the exchange rate of ligands in the first shell of the metals.

Human Fip1 is a subunit of CPSF that binds to U-rich RNA elements and stimulates poly(A) polymerase.

PubMed

Kaufmann, Isabelle; Martin, Georges; Friedlein, Arno; Langen, Hanno; Keller, Walter

2004-02-11

In mammals, polyadenylation of mRNA precursors (pre-mRNAs) by poly(A) polymerase (PAP) depends on cleavage and polyadenylation specificity factor (CPSF). CPSF is a multisubunit complex that binds to the canonical AAUAAA hexamer and to U-rich upstream sequence elements on the pre-mRNA, thereby stimulating the otherwise weakly active and nonspecific polymerase to elongate efficiently RNAs containing a poly(A) signal. Based on sequence similarity to the Saccharomyces cerevisiae polyadenylation factor Fip1p, we have identified human Fip1 (hFip1) and found that the protein is an integral subunit of CPSF. hFip1 interacts with PAP and has an arginine-rich RNA-binding motif that preferentially binds to U-rich sequence elements on the pre-mRNA. Recombinant hFip1 is sufficient to stimulate the in vitro polyadenylation activity of PAP in a U-rich element-dependent manner. hFip1, CPSF160 and PAP form a ternary complex in vitro, suggesting that hFip1 and CPSF160 act together in poly(A) site recognition and in cooperative recruitment of PAP to the RNA. These results show that hFip1 significantly contributes to CPSF-mediated stimulation of PAP activity.

Human Fip1 is a subunit of CPSF that binds to U-rich RNA elements and stimulates poly(A) polymerase

PubMed Central

Kaufmann, Isabelle; Martin, Georges; Friedlein, Arno; Langen, Hanno; Keller, Walter

2004-01-01

In mammals, polyadenylation of mRNA precursors (pre-mRNAs) by poly(A) polymerase (PAP) depends on cleavage and polyadenylation specificity factor (CPSF). CPSF is a multisubunit complex that binds to the canonical AAUAAA hexamer and to U-rich upstream sequence elements on the pre-mRNA, thereby stimulating the otherwise weakly active and nonspecific polymerase to elongate efficiently RNAs containing a poly(A) signal. Based on sequence similarity to the Saccharomyces cerevisiae polyadenylation factor Fip1p, we have identified human Fip1 (hFip1) and found that the protein is an integral subunit of CPSF. hFip1 interacts with PAP and has an arginine-rich RNA-binding motif that preferentially binds to U-rich sequence elements on the pre-mRNA. Recombinant hFip1 is sufficient to stimulate the in vitro polyadenylation activity of PAP in a U-rich element-dependent manner. hFip1, CPSF160 and PAP form a ternary complex in vitro, suggesting that hFip1 and CPSF160 act together in poly(A) site recognition and in cooperative recruitment of PAP to the RNA. These results show that hFip1 significantly contributes to CPSF-mediated stimulation of PAP activity. PMID:14749727

Structural and biochemical studies on ATP binding and hydrolysis by the Escherichia coli RNA chaperone Hfq.

PubMed

Hämmerle, Hermann; Beich-Frandsen, Mads; Večerek, Branislav; Rajkowitsch, Lukas; Carugo, Oliviero; Djinović-Carugo, Kristina; Bläsi, Udo

2012-01-01

In Escherichia coli the RNA chaperone Hfq is involved in riboregulation by assisting base-pairing between small regulatory RNAs (sRNAs) and mRNA targets. Several structural and biochemical studies revealed RNA binding sites on either surface of the donut shaped Hfq-hexamer. Whereas sRNAs are believed to contact preferentially the YKH motifs present on the proximal site, poly(A)(15) and ADP were shown to bind to tripartite binding motifs (ARE) circularly positioned on the distal site. Hfq has been reported to bind and to hydrolyze ATP. Here, we present the crystal structure of a C-terminally truncated variant of E. coli Hfq (Hfq(65)) in complex with ATP, showing that it binds to the distal R-sites. In addition, we revisited the reported ATPase activity of full length Hfq purified to homogeneity. At variance with previous reports, no ATPase activity was observed for Hfq. In addition, FRET assays neither indicated an impact of ATP on annealing of two model oligoribonucleotides nor did the presence of ATP induce strand displacement. Moreover, ATP did not lead to destabilization of binary and ternary Hfq-RNA complexes, unless a vast stoichiometric excess of ATP was used. Taken together, these studies strongly suggest that ATP is dispensable for and does not interfere with Hfq-mediated RNA transactions.

The Msd1–Wdr8–Pkl1 complex anchors microtubule minus ends to fission yeast spindle pole bodies

PubMed Central

Yukawa, Masashi; Ikebe, Chiho

2015-01-01

The minus ends of spindle microtubules are anchored to a microtubule-organizing center. The conserved Msd1/SSX2IP proteins are localized to the spindle pole body (SPB) and the centrosome in fission yeast and humans, respectively, and play a critical role in microtubule anchoring. In this paper, we show that fission yeast Msd1 forms a ternary complex with another conserved protein, Wdr8, and the minus end–directed Pkl1/kinesin-14. Individual deletion mutants displayed the identical spindle-protrusion phenotypes. Msd1 and Wdr8 were delivered by Pkl1 to mitotic SPBs, where Pkl1 was tethered through Msd1–Wdr8. The spindle-anchoring defect imposed by msd1/wdr8/pkl1 deletions was suppressed by a mutation of the plus end–directed Cut7/kinesin-5, which was shown to be mutual. Intriguingly, Pkl1 motor activity was not required for its anchoring role once targeted to the SPB. Therefore, spindle anchoring through Msd1–Wdr8–Pkl1 is crucial for balancing the Cut7/kinesin-5–mediated outward force at the SPB. Our analysis provides mechanistic insight into the spatiotemporal regulation of two opposing kinesins to ensure mitotic spindle bipolarity. PMID:25987607

Dysbindin-1, WAVE2 and Abi-1 form a complex that regulates dendritic spine formation.

PubMed

Ito, H; Morishita, R; Shinoda, T; Iwamoto, I; Sudo, K; Okamoto, K; Nagata, K

2010-10-01

Genetic variations in dysbindin-1 (dystrobrevin-binding protein-1) are one of the most commonly reported variations associated with schizophrenia. As schizophrenia could be regarded as a neurodevelopmental disorder resulting from abnormalities of synaptic connectivity, we attempted to clarify the function of dysbindin-1 in neuronal development. We examined the developmental change of dysbindin-1 in rat brain by western blotting and found that a 50 kDa isoform is highly expressed during the embryonic stage, whereas a 40 kDa one is detected at postnatal day 11 and increased thereafter. Immunofluorescent analyses revealed that dysbindin-1 is enriched at the spine-like structure of primary cultured rat hippocampal neurons. We identified WAVE2, but not N-WASP, as a binding partner for dysbindin-1. We also found that Abi-1, a binding molecule for WAVE2 involved in spine morphogenesis, interacts with dysbindin-1. Although dysbindin-1, WAVE2 and Abi-1 form a ternary complex, dysbindin-1 promoted the binding of WAVE2 to Abi-1. RNA interference-mediated knockdown of dysbindin-1 led to the generation of abnormally elongated immature dendritic protrusions. The present results indicate possible functions of dysbindin-1 at the postsynapse in the regulation of dendritic spine morphogenesis through the interaction with WAVE2 and Abi-1.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Yiming; Fredrickson, Daniel C.

Intermetallic crystal structures offer an enormous structural diversity, with an endless array of structural motifs whose connection to stability and physical properties are often mysterious. Making sense of the often complex crystal structures that arise here, developing a clear structural description, and identifying connections to other phases can be laborious and require an encyclopedic knowledge of structure types. In this Article, we present PRINCEPS, an algorithm based on a new coordination environment projection scheme that facilitates the structural analysis and comparison of such crystal structures. We demonstrate the potential of this approach by applying it to the complex Ce-Ni-Si ternarymore » system, whose 17 binary and 21 ternary phases would present a daunting challenge to one seeking to understand the system by manual inspection (but has nonetheless been well-described through the heroic efforts of previous researchers). With the help of PRINCEPS, most of the ternary phases in this system can be rationalized as intergrowths of simple structural fragments, and grouped into a handful of structural series (with some outliers). Lastly, these results illustrate how the PRINCEPS approach can be used to organize a vast collection of crystal structures into structurally meaningful families, and guide the description of complex atomic arrangements.« less

Simultaneous Speciation, Structure, and Equilibrium Constant Determination in the Ni2+-EDTA-CN- Ternary System via High-Resolution Laboratory X-ray Absorption Fine Structure Spectroscopy and Theoretical Calculations.

PubMed

Bajnóczi, Éva G; Németh, Zoltán; Vankó, György

2017-11-20

Even quite simple chemical systems can involve many components and chemical states, and sometimes it can be very difficult to differentiate them by their hardly separable physical-chemical properties. The Ni II -EDTA-CN - (EDTA = ethylenediaminetetraacetic acid) ternary system is a good example for this problem where, in spite of its fairly simple components and numerous investigations, several molecular combinations can exist, all of them not having been identified unambiguously yet. In order to achieve a detailed understanding of the reaction steps and chemical equilibria, methods are required in which the structural transitions in the different reaction steps can be followed via element-selective complex spectral feature sets. With the help of our recently developed von Hámos type high-resolution laboratory X-ray absorption spectrometer, both the structural variations and stability constants of the forming complexes were determined from the same measurement series, proving that X-ray absorption spectroscopy can be considered as a multifaced, table-top tool in coordination chemistry. Furthermore, with the help of theoretical calculations, independent structural evidence was also given for the formation of the [NiEDTA(CN)] 3- mixed complex.

Symportin 1 chaperones 5S RNP assembly during ribosome biogenesis by occupying an essential rRNA-binding site

PubMed Central

Calviño, Fabiola R.; Kharde, Satyavati; Ori, Alessandro; Hendricks, Astrid; Wild, Klemens; Kressler, Dieter; Bange, Gert; Hurt, Ed; Beck, Martin; Sinning, Irmgard

2015-01-01

During 60S biogenesis, mature 5S RNP consisting of 5S RNA, RpL5 and RpL11, assembles into a pre-60S particle, where docking relies on RpL11 interacting with helix 84 (H84) of the 25S RNA. How 5S RNP is assembled for recruitment into the pre-60S is not known. Here we report the crystal structure of a ternary symportin Syo1–RpL5-N–RpL11 complex and provide biochemical and structural insights into 5S RNP assembly. Syo1 guards the 25S RNA-binding surface on RpL11 and competes with H84 for binding. Pull-down experiments show that H84 releases RpL11 from the ternary complex, but not in the presence of 5S RNA. Crosslinking mass spectrometry visualizes structural rearrangements on incorporation of 5S RNA into the Syo1–RpL5–RpL11 complex supporting the formation of a pre-5S RNP. Our data underline the dual role of Syo1 in ribosomal protein transport and as an assembly platform for 5S RNP. PMID:25849277

Symportin 1 chaperones 5S RNP assembly during ribosome biogenesis by occupying an essential rRNA-binding site.

PubMed

Calviño, Fabiola R; Kharde, Satyavati; Ori, Alessandro; Hendricks, Astrid; Wild, Klemens; Kressler, Dieter; Bange, Gert; Hurt, Ed; Beck, Martin; Sinning, Irmgard

2015-04-07

During 60S biogenesis, mature 5S RNP consisting of 5S RNA, RpL5 and RpL11, assembles into a pre-60S particle, where docking relies on RpL11 interacting with helix 84 (H84) of the 25S RNA. How 5S RNP is assembled for recruitment into the pre-60S is not known. Here we report the crystal structure of a ternary symportin Syo1-RpL5-N-RpL11 complex and provide biochemical and structural insights into 5S RNP assembly. Syo1 guards the 25S RNA-binding surface on RpL11 and competes with H84 for binding. Pull-down experiments show that H84 releases RpL11 from the ternary complex, but not in the presence of 5S RNA. Crosslinking mass spectrometry visualizes structural rearrangements on incorporation of 5S RNA into the Syo1-RpL5-RpL11 complex supporting the formation of a pre-5S RNP. Our data underline the dual role of Syo1 in ribosomal protein transport and as an assembly platform for 5S RNP.

pH-Specific structural speciation of the ternary V(V)-peroxido-betaine system: a chemical reactivity-structure correlation.

PubMed

Gabriel, C; Kioseoglou, E; Venetis, J; Psycharis, V; Raptopoulou, C P; Terzis, A; Voyiatzis, G; Bertmer, M; Mateescu, C; Salifoglou, A

2012-06-04

Vanadium involvement in cellular processes requires deep understanding of the nature and properties of its soluble and bioavailable forms arising in aqueous speciations of binary and ternary systems. In an effort to understand the ternary vanadium-H(2)O(2)-ligand interactions relevant to that metal ion's biological role, synthetic efforts were launched involving the physiological ligands betaine (Me(3)N(+)CH(2)CO(2)(-)) and H(2)O(2). In a pH-specific fashion, V(2)O(5), betaine, and H(2)O(2) reacted and afforded three new, unusual, and unique compounds, consistent with the molecular formulation K(2)[V(2)O(2)(O(2))(4){(CH(3))(3)NCH(2)CO(2))}]·H(2)O (1), (NH(4))(2)[V(2)O(2)(O(2))(4){(CH(3))(3)NCH(2)CO(2))}]·0.75H(2)O (2), and {Na(2)[V(2)O(2)(O(2))(4){(CH(3))(3)NCH(2)CO(2))}(2)]}(n)·4nH(2)O (3). All complexes 1-3 were characterized by elemental analysis; UV/visible, FT-IR, Raman, and NMR spectroscopy in solution and the solid state; cyclic voltammetry; TGA-DTG; and X-ray crystallography. The structures of 1 and 2 reveal the presence of unusual ternary dinuclear vanadium-tetraperoxido-betaine complexes containing [(V(V)═O)(O(2))(2)] units interacting through long V-O bonds. The two V(V) ions are bridged through the oxygen terminal of one of the peroxide groups bound to the vanadium centers. The betaine ligand binds only one of the two V(V) ions. In the case of the third complex 3, the two vanadium centers are not immediate neighbors, with Na(+) ions (a) acting as efficient oxygen anchors and through Na-O bonds holding the two vanadium ions in place and (b) providing for oxygen-containing ligand binding leading to a polymeric lattice. In 1 and 3, interesting 2D (honeycomb) and 1D (zigzag chains) topologies of potassium nine-coordinate polyhedra (1) and sodium octahedra (3), respectively, form. The collective physicochemical properties of the three ternary species 1-3 project the chemical role of the low molecular mass biosubstrate betaine in binding V(V)-diperoxido units, thereby stabilizing a dinuclear V(V)-tetraperoxido dianion. Structural comparisons of the anions in 1-3 with other known dinuclear V(V)-tetraperoxido binary anionic species provide insight into the chemical reactivity of V(V)-diperoxido systems and their potential link to cellular events such as insulin mimesis and anitumorigenicity modulated by the presence of betaine.

The structure of free L11 and functional dynamics of L11 in free, L11-rRNA(58 nt) binary and L11-rRNA(58 nt)-thiostrepton ternary complexes.

PubMed

Lee, Donghan; Walsh, Joseph D; Yu, Ping; Markus, Michelle A; Choli-Papadopoulou, Theodora; Schwieters, Charles D; Krueger, Susan; Draper, David E; Wang, Yun-Xing

2007-04-06

The L11 binding site is one of the most important functional sites in the ribosome. The N-terminal domain of L11 has been implicated as a "reversible switch" in facilitating the coordinated movements associated with EF-G-driven GTP hydrolysis. The reversible switch mechanism has been hypothesized to require conformational flexibility involving re-orientation and re-positioning of the two L11 domains, and warrants a close examination of the structure and dynamics of L11. Here we report the solution structure of free L11, and relaxation studies of free L11, L11 complexed to its 58 nt RNA recognition site, and L11 in a ternary complex with the RNA and thiostrepton antibiotic. The binding site of thiostrepton on L11 was also defined by analysis of structural and dynamics data and chemical shift mapping. The conclusions of this work are as follows: first, the binding of L11 to RNA leads to sizable conformation changes in the regions flanking the linker and in the hinge area that links a beta-sheet and a 3(10)-helix-turn-helix element in the N terminus. Concurrently, the change in the relative orientation may lead to re-positioning of the N terminus, as implied by a decrease of radius of gyration from 18.5 A to 16.2 A. Second, the regions, which undergo large conformation changes, exhibit motions on milliseconds-microseconds or nanoseconds-picoseconds time scales. Third, binding of thiostrepton results in more rigid conformations near the linker (Thr71) and near its putative binding site (Leu12). Lastly, conformational changes in the putative thiostrepton binding site are implicated by the re-emergence of cross-correlation peaks in the spectrum of the ternary complex, which were missing in that of the binary complex. Our combined analysis of both the chemical shift perturbation and dynamics data clearly indicates that thiostrepton binds to a pocket involving residues in the 3(10)-helix in L11.

The Structure of Free L11 and Functional Dynamics of L11 in Free, L11-rRNA(58nt) Binary and L11-rRNA(58nt)-thiostrepton Ternary Complexes

PubMed Central

Lee, Donghan; Walsh, Joseph D.; Yu, Ping; Markus, Michelle A.; Choli-Papadopoulou, Theodora; Schwieters, Charles D.; Krueger, Susan; Draper, David E.; Wang, Yun-Xing

2007-01-01

Summary The L11 binding site is one of the most important functional sites in the ribosome. The N-terminal domain of L11 has been implicated as a “reversible switch” in facilitating the coordinated movements associated with EF-G–driven GTP hydrolysis. The “reversible switch” mechanism has been hypothesized to require conformational flexibility involving re-orientation and re-positioning of the two L11 domains, and warrants a close examination of the structure and dynamics of L11. Here we report the solution structure of free L11, and relaxation studies of free L11, L11complexed to its 58 nt RNA recognition site, and L11 in a ternary complex with the RNA and thiostrepton antibiotic. The binding site of thiostrepton on L11 was also defined by analysis of structural and dynamics data and chemical shift mapping. The conclusions of this work are as follows: First, the binding of L11 to RNA leads to sizable conformation changes in the regions flanking the linker and in the hinge area that links a β-sheets and a 310-helix-turn-helix element in the N-terminus. Concurrently, the change in the relative orientation may lead to re-positioning of the N-terminus, as implied by a decrease of radius of gyration from 18.5 Å to 16.2 Å. Second, the regions, which undergo large conformation changes, exhibit motions on ms-μs or ns-ps time scales. Third, binding of thiostrepton results in more rigid conformations near the linker (Thr71) and near its putative binding site (Leu12). Lastly, conformational changes in the putative thiostrepton binding site are implicated by the re-emergence of cross-correlation peaks in the spectrum of the ternary complex, which were missing in that of the binary complex. Our combined analysis of both the chemical shift perturbation and dynamics data clearly indicates that thiostrepton binds to a pocket involving residues in the 310-helix in L11. PMID:17292917

Low- and room-temperature X-ray structures of protein kinase A ternary complexes shed new light on its activity.

PubMed

Kovalevsky, Andrey Y; Johnson, Hanna; Hanson, B Leif; Waltman, Mary Jo; Fisher, S Zoe; Taylor, Susan; Langan, Paul

2012-07-01

Post-translational protein phosphorylation by protein kinase A (PKA) is a ubiquitous signalling mechanism which regulates many cellular processes. A low-temperature X-ray structure of the ternary complex of the PKA catalytic subunit (PKAc) with ATP and a 20-residue peptidic inhibitor (IP20) at the physiological Mg(2+) concentration of ∼0.5 mM (LT PKA-MgATP-IP20) revealed a single metal ion in the active site. The lack of a second metal in LT PKA-MgATP-IP20 renders the β- and γ-phosphoryl groups of ATP very flexible, with high thermal B factors. Thus, the second metal is crucial for tight positioning of the terminal phosphoryl group for transfer to a substrate, as demonstrated by comparison of the former structure with that of the LT PKA-Mg(2)ATP-IP20 complex obtained at high Mg(2+) concentration. In addition to its kinase activity, PKAc is also able to slowly catalyze the hydrolysis of ATP using a water molecule as a substrate. It was found that ATP can be readily and completely hydrolyzed to ADP and a free phosphate ion in the crystals of the ternary complex PKA-Mg(2)ATP-IP20 by X-ray irradiation at room temperature. The cleavage of ATP may be aided by X-ray-generated free hydroxyl radicals, a very reactive chemical species, which move rapidly through the crystal at room temperature. The phosphate anion is clearly visible in the electron-density maps; it remains in the active site but slides about 2 Å from its position in ATP towards Ala21 of IP20, which mimics the phosphorylation site. The phosphate thus pushes the peptidic inhibitor away from the product ADP, while resulting in dramatic conformational changes of the terminal residues 24 and 25 of IP20. X-ray structures of PKAc in complex with the nonhydrolysable ATP analogue AMP-PNP at both room and low temperature demonstrated no temperature effects on the conformation and position of IP20.

Multiprotein assembly of Kv4.2, KChIP3 and DPP10 produces ternary channel complexes with ISA-like properties.

PubMed

Jerng, Henry H; Kunjilwar, Kumud; Pfaffinger, Paul J

2005-11-01

Kv4 pore-forming subunits are the principal constituents of the voltage-gated K+ channel underlying somatodendritic subthreshold A-type currents (I(SA)) in neurones. Two structurally distinct types of Kv4 channel modulators, Kv channel-interacting proteins (KChIPs) and dipeptidyl-peptidase-like proteins (DPLs: DPP6 or DPPX, DPP10 or DPPY), enhance surface expression and modify functional properties. Since KChIP and DPL distributions overlap in the brain, we investigated the potential coassembly of Kv4.2, KChIP3 and DPL proteins, and the contribution of DPLs to ternary complex properties. Immunoprecipitation results show that KChIP3 and DPP10 associate simultaneously with Kv4.2 proteins in rat brain as well as heterologously expressing Xenopus oocytes, indicating Kv4.2 + KChIP3 + DPP10 multiprotein complexes. Consistent with ternary complex formation, coexpression of Kv4.2, KChIP3 and DPP10 in oocytes and CHO cells results in current waveforms distinct from the arithmetic sum of Kv4.2 + KChIP3 and Kv4.2 + DPP10 currents. Furthermore, the Kv4.2 + KChIP3 + DPP10 channels recover from inactivation very rapidly (tau(rec) approximately 18-26 ms), closely matching that of native I(SA) and significantly faster than the recovery of Kv4.2 + KChIP3 or Kv4.2 + DPP10 channels. For comparison, identical triple coexpression experiments were performed using DPP6 variants. While most results are similar, the Kv4.2 + KChIP3 + DPP6 channels exhibit inactivation that slows with increasing membrane potential, resulting in inactivation slower than that of Kv4.2 + KChIP3 + DPP10 channels at positive voltages. In conclusion, the native neuronal subthreshold A-type channel is probably a macromolecular complex formed from Kv4 and a combination of both KChIP and DPL proteins, with the precise composition of channel alpha and auxiliary subunits underlying tissue and regional variability in I(SA) properties.

Choline dehydrogenase interacts with SQSTM1/p62 to recruit LC3 and stimulate mitophagy.

PubMed

Park, Sungwoo; Choi, Seon-Guk; Yoo, Seung-Min; Son, Jin H; Jung, Yong-Keun

2014-01-01

CHDH (choline dehydrogenase) is an enzyme catalyzing the dehydrogenation of choline to betaine aldehyde in mitochondria. Apart from this well-known activity, we report here a pivotal role of CHDH in mitophagy. Knockdown of CHDH expression impairs CCCP-induced mitophagy and PARK2/parkin-mediated clearance of mitochondria in mammalian cells, including HeLa cells and SN4741 dopaminergic neuronal cells. Conversely, overexpression of CHDH accelerates PARK2-mediated mitophagy. CHDH is found on both the outer and inner membranes of mitochondria in resting cells. Interestingly, upon induction of mitophagy, CHDH accumulates on the outer membrane in a mitochondrial potential-dependent manner. We found that CHDH is not a substrate of PARK2 but interacts with SQSTM1 independently of PARK2 to recruit SQSTM1 into depolarized mitochondria. The FB1 domain of CHDH is exposed to the cytosol and is required for the interaction with SQSTM1, and overexpression of the FB1 domain only in cytosol reduces CCCP-induced mitochondrial degradation via competitive interaction with SQSTM1. In addition, CHDH, but not the CHDH FB1 deletion mutant, forms a ternary protein complex with SQSTM1 and MAP1LC3 (LC3), leading to loading of LC3 onto the damaged mitochondria via SQSTM1. Further, CHDH is crucial to the mitophagy induced by MPP+ in SN4741 cells. Overall, our results suggest that CHDH is required for PARK2-mediated mitophagy for the recruitment of SQSTM1 and LC3 onto the mitochondria for cargo recognition.

Antiangiogenic activity of semisynthetic biotechnological heparins: low-molecular-weight-sulfated Escherichia coli K5 polysaccharide derivatives as fibroblast growth factor antagonists.

PubMed

Presta, Marco; Oreste, Pasqua; Zoppetti, Giorgio; Belleri, Mirella; Tanghetti, Elena; Leali, Daria; Urbinati, Chiara; Bugatti, Antonella; Ronca, Roberto; Nicoli, Stefania; Moroni, Emanuela; Stabile, Helena; Camozzi, Maura; Hernandez, German Andrés; Mitola, Stefania; Dell'Era, Patrizia; Rusnati, Marco; Ribatti, Domenico

2005-01-01

Low-molecular-weight heparin (LMWH) exerts antitumor activity in clinical trials. The K5 polysaccharide from Escherichia coli has the same structure as the heparin precursor. Chemical and enzymatic modifications of K5 polysaccharide lead to the production of biotechnological heparin-like compounds. We investigated the fibroblast growth factor-2 (FGF2) antagonist and antiangiogenic activity of a series of LMW N,O-sulfated K5 derivatives. Surface plasmon resonance analysis showed that LMW-K5 derivatives bind FGF2, thus inhibiting its interaction with heparin immobilized to a BIAcore sensor chip. Interaction of FGF2 with tyrosine-kinase receptors (FGFRs), heparan sulfate proteoglycans (HSPGs), and alpha(v)beta3 integrin is required for biological response in endothelial cells. Similar to LMWH, LMW-K5 derivatives abrogate the formation of HSPG/FGF2/FGFR ternary complexes by preventing FGF2-mediated attachment of FGFR1-overexpressing cells to HSPG-bearing cells and inhibit FGF2-mediated endothelial cell proliferation. However, LMW-K5 derivatives, but not LMWH, also inhibit FGF2/alpha(v)beta3 integrin interaction and consequent FGF2-mediated endothelial cell sprouting in vitro and angiogenesis in vivo in the chick embryo chorioallantoic membrane. LMW N,O-sulfated K5 derivatives affect both HSPG/FGF2/FGFR and FGF2/alpha(v)beta3 interactions and are endowed with FGF2 antagonist and antiangiogenic activity. These compounds may provide the basis for the design of novel LMW heparin-like angiostatic compounds.

Structural evolution of dilute magnetic (Sn,Mn)Se films grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Kanzyuba, Vasily; Dong, Sining; Liu, Xinyu; Li, Xiang; Rouvimov, Sergei; Okuno, Hanako; Mariette, Henri; Zhang, Xueqiang; Ptasinska, Sylwia; Tracy, Brian D.; Smith, David J.; Dobrowolska, Margaret; Furdyna, Jacek K.

2017-02-01

We describe the structural evolution of dilute magnetic (Sn,Mn)Se films grown by molecular beam epitaxy on GaAs (111) substrates, as revealed by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. When the Mn concentration is increased, the lattice of the ternary (Sn,Mn)Se films evolves quasi-coherently from a SnSe2 two-dimensional (2D) crystal structure into a more complex quasi-2D lattice rearrangement, ultimately transforming into the magnetically concentrated antiferromagnetic MnSe 3D rock-salt structure as Mn approaches 50 at. % of this material. These structural transformations are expected to underlie the evolution of magnetic properties of this ternary system reported earlier in the literature.

Non-covalent doping of graphitic carbon nitride with ultrathin graphene oxide and molybdenum disulfide nanosheets: an effective binary heterojunction photocatalyst under visible light irradiation.

PubMed

Hu, S W; Yang, L W; Tian, Y; Wei, X L; Ding, J W; Zhong, J X; Chu, Paul K

2014-10-01

A proof of concept integrating binary p-n heterojunctions into a semiconductor hybrid photocatalyst is demonstrated by non-covalent doping of graphite-like carbon nitride (g-C3N4) with ultrathin GO and MoS2 nanosheets using a facile sonochemical method. In this unique ternary hybrid, the layered MoS2 and GO nanosheets with a large surface area enhance light absorption to generate more photoelectrons. On account of the coupling between MoS2 and GO with g-C3N4, the ternary hybrid possesses binary p-n heterojunctions at the g-C3N4/MoS2 and g-C3N4/GO interfaces. The space charge layers created by the p-n heterojunctions not only enhance photogeneration, but also promote charge separation and transfer of electron-hole pairs. In addition, the ultrathin MoS2 and GO with high mobility act as electron mediators to facilitate separation of photogenerated electron-hole pairs at each p-n heterojunction. As a result, the ternary hybrid photocatalyst exhibits improved photoelectrochemical and photocatalytic activity under visible light irradiation compared to other reference materials. The results provide new insights into the large-scale production of semiconductor photocatalysts. Copyright © 2014 Elsevier Inc. All rights reserved.

Amsacrine as a Topoisomerase II Poison: Importance of Drug-DNA Interactions†

PubMed Central

Ketron, Adam C.; Denny, William A.; Graves, David E.; Osheroff, Neil

2012-01-01

Amsacrine (m-AMSA) is an anticancer agent that displays activity against refractory acute leukemias as well as Hodgkin’s and non-Hodgkin’s lymphomas. The drug is comprised of an intercalative acridine moiety coupled to a 4’-amino-methanesulfon-m-anisidide head group. m-AMSA is historically significant in that it was the first drug demonstrated to function as a topoisomerase II poison. Although m-AMSA was designed as a DNA binding agent, the ability to intercalate does not appear to be the sole determinant of drug activity. Therefore, to more fully analyze structure-function relationships and the role of DNA binding in the action of m-AMSA, we analyzed a series of derivatives for the ability to enhance DNA cleavage mediated by human topoisomerase IIα and topoisomerase IIβ and to intercalate DNA. Results indicate that the 3’-methoxy (m-AMSA) positively affects drug function, potentially by restricting the rotation of the head group in a favorable orientation. Shifting the methoxy to the 2’-position (o-AMSA), which abrogates drug function, appears to increase rotational freedom of the head group and may impair interactions of the 1’-substituent or other portions of the head group within the ternary complex. Finally, the non-intercalative m-AMSA head group enhanced enzyme-mediated DNA cleavage when it was detached from the acridine moiety, albeit with 100-fold lower affinity. Taken together, our results suggest that much of the activity and specificity of m-AMSA as a topoisomerase II poison is embodied in the head group, while DNA intercalation is used primarily to increase the affinity of m-AMSA for the topoisomerase II-DNA cleavage complex. PMID:22304499

HPK1 competes with ADAP for SLP-76 binding and via Rap1 negatively affects T-cell adhesion.

PubMed

Patzak, Irene M; Königsberger, Sebastian; Suzuki, Akira; Mak, Tak W; Kiefer, Friedemann

2010-11-01

The hematopoietic progenitor kinase 1 (HPK1) signals into MAPK and NFκB pathways downstream of immunoreceptors, but enigmatically is a negative regulator of leukocytes. Here, we report a novel role for HPK1 in regulating the activation of the adhesion molecule leukocyte function-associated antigen-1 (LFA-1). Upon TCR stimulation, mediated by binding of adhesion and degranulation promoting adaptor protein (ADAP) to SLP-76, a ternary complex composed of ADAP/55-kDa src kinase associated phosphoprotein (SKAP-55) and RIAM translocates to the membrane and causes membrane recruitment of the active small GTPase Ras-related protein 1 (Rap1). Active Rap1, via its binding to RapL (regulator for cell adhesion and polarization enriched in lymphoid tissues), mediates LFA-1 integrin activation. We show here that HPK1, which also binds SLP-76, compete with ADAP for SLP-76 binding. In addition, HPK1 dampens Rap1 activation, resulting in decreased LFA-1 activity. Analysis of HPK1-deficient T cells revealed increased ADAP recruitment to SLP-76 and elevated Rap1 activation in those cells, leading to increased adhesion to ICAM-1 and cell spreading. Altogether, these results describe a novel function for HPK1 in linking TCR signaling to cell adhesion regulation and provide a mechanistic explanation for the negative regulatory role of HPK1 in T-cell biology.

A Supercomplex Spanning the Inner and Outer Membranes Mediates the Biogenesis of β-Barrel Outer Membrane Proteins in Bacteria.

PubMed

Wang, Yan; Wang, Rui; Jin, Feng; Liu, Yang; Yu, Jiayu; Fu, Xinmiao; Chang, Zengyi

2016-08-05

β-barrel outer membrane proteins (OMPs) are ubiquitously present in Gram-negative bacteria, mitochondria and chloroplasts, and function in a variety of biological processes. The mechanism by which the hydrophobic nascent β-barrel OMPs are transported through the hydrophilic periplasmic space in bacterial cells remains elusive. Here, mainly via unnatural amino acid-mediated in vivo photo-crosslinking studies, we revealed that the primary periplasmic chaperone SurA interacts with nascent β-barrel OMPs largely via its N-domain but with β-barrel assembly machine protein BamA mainly via its satellite P2 domain, and that the nascent β-barrel OMPs interact with SurA via their N- and C-terminal regions. Additionally, via dual in vivo photo-crosslinking, we demonstrated the formation of a ternary complex involving β-barrel OMP, SurA, and BamA in cells. More importantly, we found that a supercomplex spanning the inner and outer membranes and involving the BamA, BamB, SurA, PpiD, SecY, SecE, and SecA proteins appears to exist in living cells, as revealed by a combined analyses of sucrose-gradient ultra-centrifugation, Blue native PAGE and mass spectrometry. We propose that this supercomplex integrates the translocation, transportation, and membrane insertion events for β-barrel OMP biogenesis. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

A Supercomplex Spanning the Inner and Outer Membranes Mediates the Biogenesis of β-Barrel Outer Membrane Proteins in Bacteria*

PubMed Central

Wang, Yan; Wang, Rui; Jin, Feng; Liu, Yang; Yu, Jiayu; Fu, Xinmiao; Chang, Zengyi

2016-01-01

β-barrel outer membrane proteins (OMPs) are ubiquitously present in Gram-negative bacteria, mitochondria and chloroplasts, and function in a variety of biological processes. The mechanism by which the hydrophobic nascent β-barrel OMPs are transported through the hydrophilic periplasmic space in bacterial cells remains elusive. Here, mainly via unnatural amino acid-mediated in vivo photo-crosslinking studies, we revealed that the primary periplasmic chaperone SurA interacts with nascent β-barrel OMPs largely via its N-domain but with β-barrel assembly machine protein BamA mainly via its satellite P2 domain, and that the nascent β-barrel OMPs interact with SurA via their N- and C-terminal regions. Additionally, via dual in vivo photo-crosslinking, we demonstrated the formation of a ternary complex involving β-barrel OMP, SurA, and BamA in cells. More importantly, we found that a supercomplex spanning the inner and outer membranes and involving the BamA, BamB, SurA, PpiD, SecY, SecE, and SecA proteins appears to exist in living cells, as revealed by a combined analyses of sucrose-gradient ultra-centrifugation, Blue native PAGE and mass spectrometry. We propose that this supercomplex integrates the translocation, transportation, and membrane insertion events for β-barrel OMP biogenesis. PMID:27298319

Sorption of trivalent lanthanides and actinides onto montmorillonite: Macroscopic, thermodynamic and structural evidence for ternary hydroxo and carbonato surface complexes on multiple sorption sites.

PubMed

Fernandes, M Marques; Scheinost, A C; Baeyens, B

2016-08-01

The credibility of long-term safety assessments of radioactive waste repositories may be greatly enhanced by a molecular level understanding of the sorption processes onto individual minerals present in the near- and far-fields. In this study we couple macroscopic sorption experiments to surface complexation modelling and spectroscopic investigations, including extended X-ray absorption fine structure (EXAFS) and time-resolved laser fluorescence spectroscopies (TRLFS), to elucidate the uptake mechanism of trivalent lanthanides and actinides (Ln/An(III)) by montmorillonite in the absence and presence of dissolved carbonate. Based on the experimental sorption isotherms for the carbonate-free system, the previously developed 2 site protolysis non electrostatic surface complexation and cation exchange (2SPNE SC/CE) model needed to be complemented with an additional surface complexation reaction onto weak sites. The fitting of sorption isotherms in the presence of carbonate required refinement of the previously published model by reducing the strong site capacity and by adding the formation of Ln/An(III)-carbonato complexes both on strong and weak sites. EXAFS spectra of selected Am samples and TRLFS spectra of selected Cm samples corroborate the model assumptions by showing the existence of different surface complexation sites and evidencing the formation of Ln/An(III) carbonate surface complexes. In the absence of carbonate and at low loadings, Ln/An(III) form strong inner-sphere complexes through binding to three Al(O,OH)6 octahedra, most likely by occupying vacant sites in the octahedral layers of montmorillonite, which are exposed on {010} and {110} edge faces. At higher loadings, Ln/An(III) binds to only one Al octahedron, forming a weaker, edge-sharing surface complex. In the presence of carbonate, we identified a ternary mono- or dicarbonato Ln/An(III) complex binding directly to one Al(O,OH)6 octahedron, revealing that type-A ternary complexes form with the one or two carbonate groups pointing away from the surface into the solution phase. Within the spectroscopically observable concentration range these complexes could only be identified on the weak sites, in line with the small strong site capacity suggested by the refined sorption model. When the solubility of carbonates was exceeded, formation of an Am carbonate hydroxide could be identified. The excellent agreement between the thermodynamic model parameters obtained by fitting the macroscopic data, and the spectroscopically identified mechanisms, demonstrates the mature state of the 2SPNE SC/CE model for predicting and quantifying the retention of Ln/An(III) elements by montmorillonite-rich clay rocks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Molecular basis of cannabinoid CB1 receptor coupling to the G protein heterotrimer Gαiβγ: identification of key CB1 contacts with the C-terminal helix α5 of Gαi.

PubMed

Shim, Joong-Youn; Ahn, Kwang H; Kendall, Debra A

2013-11-08

The cannabinoid (CB1) receptor is a member of the rhodopsin-like G protein-coupled receptor superfamily. The human CB1 receptor, which is among the most expressed receptors in the brain, has been implicated in several disease states, including drug addiction, anxiety, depression, obesity, and chronic pain. Different classes of CB1 agonists evoke signaling pathways through the activation of specific subtypes of G proteins. The molecular basis of CB1 receptor coupling to its cognate G protein is unknown. As a first step toward understanding CB1 receptor-mediated G protein signaling, we have constructed a ternary complex structural model of the CB1 receptor and Gi heterotrimer (CB1-Gi), guided by the x-ray structure of β2-adrenergic receptor (β2AR) in complex with Gs (β2AR-Gs), through 824-ns duration molecular dynamics simulations in a fully hydrated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer environment. We identified a group of residues at the juxtamembrane regions of the intracellular loops 2 and 3 (IC2 and IC3) of the CB1 receptor, including Ile-218(3.54), Tyr-224(IC2), Asp-338(6.30), Arg-340(6.32), Leu-341(6.33), and Thr-344(6.36), as potential key contacts with the extreme C-terminal helix α5 of Gαi. Ala mutations of these residues at the receptor-Gi interface resulted in little G protein coupling activity, consistent with the present model of the CB1-Gi complex, which suggests tight interactions between CB1 and the extreme C-terminal helix α5 of Gαi. The model also suggests that unique conformational changes in the extreme C-terminal helix α5 of Gα play a crucial role in the receptor-mediated G protein activation.

The powdery mildew resistance protein RPW8.2 is carried on VAMP721/722 vesicles to the extrahaustorial membrane of haustorial complexes.

PubMed

Kim, Hyeran; O'Connell, Richard; Maekawa-Yoshikawa, Makoto; Uemura, Tomohiro; Neumann, Ulla; Schulze-Lefert, Paul

2014-09-01

Plants employ multiple cell-autonomous defense mechanisms to impede pathogenesis of microbial intruders. Previously we identified an exocytosis defense mechanism in Arabidopsis against pathogenic powdery mildew fungi. This pre-invasive defense mechanism depends on the formation of ternary protein complexes consisting of the plasma membrane-localized PEN1 syntaxin, the adaptor protein SNAP33 and closely sequence-related vesicle-resident VAMP721 or VAMP722 proteins. The Arabidopsis thaliana resistance to powdery mildew 8.2 protein (RPW8.2) confers disease resistance against powdery mildews upon fungal entry into host cells and is specifically targeted to the extrahaustorial membrane (EHM), which envelops the haustorial complex of the fungus. However, the secretory machinery involved in trafficking RPW8.2 to the EHM is unknown. Here we report that RPW8.2 is transiently located on VAMP721/722 vesicles, and later incorporated into the EHM of mature haustoria. Resistance activity of RPW8.2 against the powdery mildew Golovinomyces orontii is greatly diminished in the absence of VAMP721 but only slightly so in the absence of VAMP722. Consistent with this result, trafficking of RPW8.2 to the EHM is delayed in the absence of VAMP721. These findings implicate VAMP721/722 vesicles as key components of the secretory machinery for carrying RPW8.2 to the plant-fungal interface. Quantitative fluorescence recovery after photobleaching suggests that vesicle-mediated trafficking of RPW8.2-yellow fluorescent protein (YFP) to the EHM occurs transiently during early haustorial development and that lateral diffusion of RPW8.2-YFP within the EHM exceeds vesicle-mediated replenishment of RPW8.2-YFP in mature haustoria. Our findings imply the engagement of VAMP721/722 in a bifurcated trafficking pathway for pre-invasive defense at the cell periphery and post-invasive defense at the EHM. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

Bridging of a substrate between cyclodextrin and an enzyme’s active site pocket triggers a unique mode of inhibition

PubMed Central

Sule, Nitesh V; Ugrinov, Angel; Mallik, Sanku; Srivastava, D. K.

2014-01-01

Background Methionyl-7-amino-4-methylcoumarin (MetAMC) serves as a substrate for the E. coli Methionine aminopeptidase (MetAP) catalyzed reaction, and is routinely used for screening compounds to identify potential antibiotic agents. In pursuit of screening the enzyme’s inhibitors, we observed that 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), utilized to solubilize hydrophobic inhibitors, inhibited the catalytic activity of the enzyme, and such inhibition was not solely due to sequestration of the substrate by HP-β-CD. Methods The mechanistic path for the HP-β-CD mediated inhibition of MetAP was probed by performing a detailed account of steady-state kinetics, ligand binding, X-ray crystallographic, and molecular modeling studies. Results X-ray crystallographic data of the β-cyclodextrin—substrate (β-CD—MetAMC) complex reveal that while the AMC moiety of the substrate is confined within the CD cavity, the methionine moiety protrudes outward. The steady-state kinetic data for inhibition of MetAP by HP-β-CD—MetAMC conform to a model mechanism in which the substrate is “bridged” between HP-β-CD and the enzyme’s active-site pocket, forming HP-β-CD—MetAMC—MetAP as the catalytically inactive ternary complex. Molecular modeling shows that the scissile bond of HP-β-CD-bound MetAMC substrate does not reach within the proximity of the enzyme’s catalytic metal center, and thus the substrate fails to undergo cleavage. Conclusions The data presented herein suggests that the bridging of the substrate between the enzyme and HP-β-CD cavities is facilitated by interaction of their surfaces, and the resulting complex inhibits the enzyme activity. General Significance Due to its potential interaction with physiological proteins via sequestered substrates, caution must be exercised in HP-β-CD mediated delivery of drugs under pathophysiological conditions. PMID:25450177

Zone leveling and solution growth of complex compound semiconductors in space

NASA Technical Reports Server (NTRS)

Bachmann, K. J.

1986-01-01

A research program on complex semiconducting compounds and alloys was completed that addressed the growth of single crystals of CdSe(y)Te(1-y), Zn(x)Cd(1-x)Te, Mn(x)Cd(1-x)Te, InP(y)As(1-y) and CuInSe2 and the measurement of fundamental physico-chemical properties characterizing the above materials. The purpose of this ground based research program was to lay the foundations for further research concerning the growth of complex ternary compound semiconductors in a microgravity environment.

Acute Toxicity of Ternary Cd-Cu-Ni and Cd-Ni-Zn Mixtures to Daphnia magna: Dominant Metal Pairs Change along a Concentration Gradient.

PubMed

Traudt, Elizabeth M; Ranville, James F; Meyer, Joseph S

2017-04-18

Multiple metals are usually present in surface waters, sometimes leading to toxicity that currently is difficult to predict due to potentially non-additive mixture toxicity. Previous toxicity tests with Daphnia magna exposed to binary mixtures of Ni combined with Cd, Cu, or Zn demonstrated that Ni and Zn strongly protect against Cd toxicity, but Cu-Ni toxicity is more than additive, and Ni-Zn toxicity is slightly less than additive. To consider multiple metal-metal interactions, we exposed D. magna neonates to Cd, Cu, Ni, or Zn alone and in ternary Cd-Cu-Ni and Cd-Ni-Zn combinations in standard 48 h lethality tests. In these ternary mixtures, two metals were held constant, while the third metal was varied through a series that ranged from nonlethal to lethal concentrations. In Cd-Cu-Ni mixtures, the toxicity was less than additive, additive, or more than additive, depending on the concentration (or ion activity) of the varied metal and the additivity model (concentration-addition or independent-action) used to predict toxicity. In Cd-Ni-Zn mixtures, the toxicity was less than additive or approximately additive, depending on the concentration (or ion activity) of the varied metal but independent of the additivity model. These results demonstrate that complex interactions of potentially competing toxicity-controlling mechanisms can occur in ternary-metal mixtures but might be predicted by mechanistic bioavailability-based toxicity models.

Luminescence properties and warm white LED application of a ternary-alkaline fluoride red phosphor K2NaAlF6:Mn4+ .

PubMed

Wang, L Y; Song, E H; Deng, T T; Zhou, Y Y; Liao, Z F; Zhao, W R; Zhou, B; Zhang, Q Y

2017-08-14

Herein, a Mn 4+ ion doped complex ternary-alkaline fluoride red phosphor K 2 NaAlF 6 :Mn 4+ has been synthesized through a facile two-step co-precipitation method at room temperature. The crystal structure, morphological properties and influence of the dopant concentration, temperature and humidity on luminescence properties as well as the performance of the as-synthesized phosphor used in white light emitting diodes (WLEDs) were investigated carefully. Intense absorption in the blue region (∼460 nm) and bright narrow-band red emission (∼630 nm) with high color purity were observed from this resultant powder. Temperature-dependent investigation and reliability examination in a HTHH environment (85 °C high temperature and 85% high humidity) indicate that the obtained ternary-alkaline fluoride phosphor K 2 NaAlF 6 :Mn 4+ presents more exceptional thermal quenching behavior and longevity compared to some other binary-alkaline fluorides. Moreover, using K 2 NaAlF 6 :Mn 4+ as a red light component, a warm WLED with a preferable color rendering index (R a = 85.5) and luminous efficacy (LE = 91.2 lm W -1 ) as well as a low corresponding color temperature (CCT = 3650 K) is easily achieved, further revealing the great potential of the as-prepared ternary-alkaline fluoride red phosphor K 2 NaAlF 6 :Mn 4+ for WLED applications.

Interaction of classical platinum agents with the monomeric and dimeric Atox1 proteins: a molecular dynamics simulation study.

PubMed

Wang, Xiaolei; Li, Chaoqun; Wang, Yan; Chen, Guangju

2013-12-20

We carried out molecular dynamics simulations and free energy calculations for a series of binary and ternary models of the cisplatin, transplatin and oxaliplatin agents binding to a monomeric Atox1 protein and a dimeric Atox1 protein to investigate their interaction mechanisms. All three platinum agents could respectively combine with the monomeric Atox1 protein and the dimeric Atox1 protein to form a stable binary and ternary complex due to the covalent interaction of the platinum center with the Atox1 protein. The results suggested that the extra interaction from the oxaliplatin ligand-Atox1 protein interface increases its affinity only for the OxaliPt + Atox1 model. The binding of the oxaliplatin agent to the Atox1 protein might cause larger deformation of the protein than those of the cisplatin and transplatin agents due to the larger size of the oxaliplatin ligand. However, the extra interactions to facilitate the stabilities of the ternary CisPt + 2Atox1 and OxaliPt + 2Atox1 models come from the α1 helices and α2-β4 loops of the Atox1 protein-Atox1 protein interface due to the cis conformation of the platinum agents. The combinations of two Atox1 proteins in an asymmetric way in the three ternary models were analyzed. These investigations might provide detailed information for understanding the interaction mechanism of the platinum agents binding to the Atox1 protein in the cytoplasm.

Evidence for a ternary complex formed between flavodoxin and cytochrome c3: 1H-NMR and molecular modeling studies.

PubMed

Palma, P N; Moura, I; LeGall, J; Van Beeumen, J; Wampler, J E; Moura, J J

1994-05-31

Small electron-transfer proteins such as flavodoxin (16 kDa) and the tetraheme cytochrome c3 (13 kDa) have been used to mimic, in vitro, part of the complex electron-transfer chain operating between substrate electron donors and respiratory electron acceptors, in sulfate-reducing bacteria (Desulfovibrio species). The nature and properties of the complex formed between these proteins are revealed by 1H-NMR and molecular modeling approaches. Our previous study with the Desulfovibrio vulgaris proteins [Moura, I., Moura, J.J. G., Santos, M.H., & Xavier, A. V. (1980) Cienc. Biol. (Portugal) 5, 195-197; Stewart, D.E. LeGall, J., Moura, I., Moura, J. J. G., Peck, H.D. Jr., Xavier, A. V., Weiner, P. K., & Wampler, J.E. (1988) Biochemistry 27, 2444-2450] indicated that the complex between cytochrome c3 and flavodoxin could be monitored by changes in the NMR signals of the heme methyl groups of the cytochrome and that the electrostatic surface charge (Coulomb's law) on the two proteins favored interaction between one unique heme of the cytochrome with flavodoxin. If the interaction is indeed driven by the electrostatic complementarity between the acidic flavodoxin and a unique positive region of the cytochrome c3, other homologous proteins from these two families of proteins might be expected to interact similarly. In this study, three homologous Desulfovibrio cytochromes c3 were used, which show a remarkable variation in their individual isoelectric points (ranging from 5.5 to 9.5). On the basis of data obtained from protein-protein titrations followed at specific proton NMR signals (i.e., heme methyl resonances), a binding model for this complex has been developed with evaluation of stoichiometry and binding constants. This binding model involves one site on the cytochromes c3 and two sites on the flavodoxin, with formation of a ternary complex at saturation. In order to understand the potential chemical form of the binding model, a structural model for the hypothetical ternary complex, formed between one molecule of Desulfovibrio salexigens flavodoxin and two molecules of cytochrome c3, is proposed. These molecular models of the complexes were constructed on the basis of complementarity of Coulombic electrostatic surface potentials, using the available X-ray structures of the isolated proteins and, when required, model structures (D. salexigens flavodoxin and Desulfovibrio desulfuricans ATCC 27774 cytochrome c3) predicted by homology modeling.

Dipicolinic Acid Derivatives as Inhibitors of New Delhi Metallo-β-lactamase-1.

PubMed

Chen, Allie Y; Thomas, Pei W; Stewart, Alesha C; Bergstrom, Alexander; Cheng, Zishuo; Miller, Callie; Bethel, Christopher R; Marshall, Steven H; Credille, Cy V; Riley, Christopher L; Page, Richard C; Bonomo, Robert A; Crowder, Michael W; Tierney, David L; Fast, Walter; Cohen, Seth M

2017-09-14

The efficacy of β-lactam antibiotics is threatened by the emergence and global spread of metallo-β-lactamase (MBL) mediated resistance, specifically New Delhi metallo-β-lactamase-1 (NDM-1). By utilization of fragment-based drug discovery (FBDD), a new class of inhibitors for NDM-1 and two related β-lactamases, IMP-1 and VIM-2, was identified. On the basis of 2,6-dipicolinic acid (DPA), several libraries were synthesized for structure-activity relationship (SAR) analysis. Inhibitor 36 (IC 50 = 80 nM) was identified to be highly selective for MBLs when compared to other Zn(II) metalloenzymes. While DPA displayed a propensity to chelate metal ions from NDM-1, 36 formed a stable NDM-1:Zn(II):inhibitor ternary complex, as demonstrated by 1 H NMR, electron paramagnetic resonance (EPR) spectroscopy, equilibrium dialysis, intrinsic tryptophan fluorescence emission, and UV-vis spectroscopy. When coadministered with 36 (at concentrations nontoxic to mammalian cells), the minimum inhibitory concentrations (MICs) of imipenem against clinical isolates of Eschericia coli and Klebsiella pneumoniae harboring NDM-1 were reduced to susceptible levels.

T cell receptor cross-reactivity directed by antigen-dependent tuning of peptide-MHC molecular flexibility

PubMed Central

Borbulevych, Oleg Y.; Piepenbrink, Kurt H.; Gloor, Brian E.; Scott, Daniel R.; Sommese, Ruth F.; Cole, David K.; Sewell, Andrew K.; Baker, Brian M.

2011-01-01

Summary Tell mediated immunity requires T cell receptor (TCR) cross-reactivity, the mechanisms behind which remain incompletely elucidated. The αβ TCR A6 recognizes both the Tax (LLFGYPVYV) and Tel1p (MLWGYLQYV) peptides presented by the human class I MHC molecule HLA-A2. Here we found that although the two ligands are ideal structural mimics, they form substantially different interfaces with A6, with conformational differences in the peptide, the TCR, and unexpectedly, the MHC molecule. The differences between the Tax and Tel1p ternary complexes could not be predicted from the free peptide-MHC structures and are inconsistent with a traditional induced-fit mechanism. Instead, the differences were attributable to peptide and MHC molecular motion present in Tel1p-HLA-A2 but absent in Tax-HLA-A2. Differential “tuning” of the dynamic properties of HLA-A2 by the Tax and Tel1p peptides thus facilitates cross-recognition and impacts how structural diversity can be presented to and accommodated by receptors of the immune system. PMID:20064447

Ubiquitous Nature of Fluoroquinolones: The Oscillation between Antibacterial and Anticancer Activities

PubMed Central

Schweizer, Frank

2017-01-01

Fluoroquinolones are synthetic antibacterial agents that stabilize the ternary complex of prokaryotic topoisomerase II enzymes (gyrase and Topo IV), leading to extensive DNA fragmentation and bacteria death. Despite the similar structural folds within the critical regions of prokaryotic and eukaryotic topoisomerases, clinically relevant fluoroquinolones display a remarkable selectivity for prokaryotic topoisomerase II, with excellent safety records in humans. Typical agents that target human topoisomerases (such as etoposide, doxorubicin and mitoxantrone) are associated with significant toxicities and secondary malignancies, whereas clinically relevant fluoroquinolones are not known to exhibit such propensities. Although many fluoroquinolones have been shown to display topoisomerase-independent antiproliferative effects against various human cancer cells, those that are significantly active against eukaryotic topoisomerase show the same DNA damaging properties as other topoisomerase poisons. Empirical models also show that fluoroquinolones mediate some unique immunomodulatory activities of suppressing pro-inflammatory cytokines and super-inducing interleukin-2. This article reviews the extended roles of fluoroquinolones and their prospects as lead for the unmet needs of “small and safe” multimodal-targeting drug scaffolds. PMID:29112154

Composition control and localization of S2- in CdSSe quantum dots grown from Li4[Cd10Se4(SPh)16].

PubMed

Lovingood, Derek D; Oyler, Ryan E; Strouse, Geoffrey F

2008-12-17

The development of ternary nanoscale materials with controlled cross-sectional doping is an important step for the use of chemically prepared quantum dots for nanoscale engineering applications. We report cross-sectional, elemental doping with the formation of an alloyed CdSSe nanocrystal from the thermal decomposition of Li(4)[Cd(10)Se(4)(SPh)(16)]. The sulfur incorporation arises from surface-mediated phenylthiolate degradation on the growing quantum dot surface. In the alloy, we identify a pure CdSe nucleus of approximately 1.5 nm, consistent with the predictions of nucleation theory. As the particle grows, S(2-) incorporation increases until the CdSSe reaches approximately 4 nm, where a marked reduction in phenylthiolate content on the nanocrystal is observed by CP-MAS NMR spectroscopy, implying that rapid decomposition of the phenylthiolate arises with subsequent enhanced S(2-) incorporation at the level of the stoichiometry of the reaction (namely approximately 60%). The use of molecular clusters to allow controlled defect ion incorporation can open new pathways to more complex nanomaterials.

Characterization of the ternary Usher syndrome SANS/ush2a/whirlin protein complex.

PubMed

Sorusch, Nasrin; Bauß, Katharina; Plutniok, Janet; Samanta, Ananya; Knapp, Barbara; Nagel-Wolfrum, Kerstin; Wolfrum, Uwe

2017-03-15

The Usher syndrome (USH) is the most common form of inherited deaf-blindness, accompanied by vestibular dysfunction. Due to the heterogeneous manifestation of the clinical symptoms, three USH types (USH1-3) and additional atypical forms are distinguished. USH1 and USH2 proteins have been shown to function together in multiprotein networks in photoreceptor cells and hair cells. Mutations in USH proteins are considered to disrupt distinct USH protein networks and finally lead to the development of USH.To get novel insights into the molecular pathomechanisms underlying USH, we further characterize the periciliary USH protein network in photoreceptor cells. We show the direct interaction between the scaffold protein SANS (USH1G) and the transmembrane adhesion protein ush2a and that both assemble into a ternary USH1/USH2 complex together with the PDZ-domain protein whirlin (USH2D) via mutual interactions. Immunohistochemistry and proximity ligation assays demonstrate co-localization of complex partners and complex formation, respectively, in the periciliary region, the inner segment and at the synapses of rodent and human photoreceptor cells. Protein-protein interaction assays and co-expression of complex partners reveal that pathogenic mutations in USH1G severely affect formation of the SANS/ush2a/whirlin complex. Translational read-through drug treatment, targeting the c.728C > A (p.S243X) nonsense mutation, restored SANS scaffold function. We conclude that USH1 and USH2 proteins function together in higher order protein complexes. The maintenance of USH1/USH2 protein complexes depends on multiple USH1/USH2 protein interactions, which are disrupted by pathogenic mutations in USH1G protein SANS. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Synthesis, investigation and spectroscopic characterization of piroxicam ternary complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with glycine and DL-phenylalanine.

PubMed

Mohamed, Gehad G; El-Gamel, Nadia E A

2004-11-01

The ternary piroxicam (Pir; 4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide) complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with various amino acids (AA) such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized by elemental analyses, molar conductance, IR, UV-Vis, magnetic moment, diffuse reflectance and X-ray powder diffraction. The UV-Vis spectra of Pir and the effect of metal chelation on the different interligand transitions are discussed in detailed manner. IR and UV-Vis spectra confirm that Pir behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its carboxylic group, in addition PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its carboxylic and amino groups. All the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. The molar conductance data reveal that most of these chelates are non electrolytes, while Fe(III)-Pir-Gly, Co(II)-, Ni(II)-, Cu(II)- and Zn(II)-Pir-PhA chelates were 1:1 electrolytes. X-ray powder diffraction is used as a new tool to estimate the crystallinity of chelates as well as to elucidate their geometrical structures.

Synthesis, investigation and spectroscopic characterization of piroxicam ternary complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with glycine and DL-phenylalanine

NASA Astrophysics Data System (ADS)

Mohamed, Gehad G.; El-Gamel, Nadia E. A.

2004-11-01

The ternary piroxicam (Pir; 4-hydroxy-2-methyl- N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide) complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with various amino acids (AA) such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized by elemental analyses, molar conductance, IR, UV-Vis, magnetic moment, diffuse reflectance and X-ray powder diffraction. The UV-Vis spectra of Pir and the effect of metal chelation on the different interligand transitions are discussed in detailed manner. IR and UV-Vis spectra confirm that Pir behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine- N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its carboxylic group, in addition PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its carboxylic and amino groups. All the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. The molar conductance data reveal that most of these chelates are non electrolytes, while Fe(III)-Pir-Gly, Co(II)-, Ni(II)-, Cu(II)- and Zn(II)-Pir-PhA cheletes were 1:1 electrolytes. X-ray powder diffraction is used as a new tool to estimate the crystallinity of chelates as well as to elucidate their geometrical structures.

Interactions Among Plants, Insects, and Microbes: Elucidation of Inter-Organismal Chemical Communications in Agricultural Ecology.

PubMed

Beck, John J; Alborn, Hans; Block, Anna; Christensen, Shawn A; Hunter, Charles T; Rering, Caitlin C; Seidl-Adams, Irmgard; Stuhl, Charles; Torto, Baldwyn; Tumlinson, James H

2018-06-12

The last two decades have witnessed a sustained increase in the study of plant-emitted volatiles and their role in plant-insect, plant-microbe and plant-plant interactions. While each of these binary systems involves complex chemical and biochemical processes between two organisms, the progression of increasing complexity of a ternary system (i.e., plant-insect-microbe), and the study of a ternary system requires non-trivial planning. This planning can include: an experimental design that factors in potential overarching ecological interactions regarding the binary or ternary system; correctly identifying and understanding unexpected observations that may occur during the experiment; and, thorough interpretation of the resultant data. This challenge of planning, performing and interpreting a plant's defensive response to multiple biotic stressors will be even greater when abiotic stressors (i.e., temperature or water) are factored into the system. To fully understand the system, we need to not only continue to investigate and understand the volatile profiles, but also include and understand the biochemistry of the plant's response to these stressors. In this paper, we provide examples and discuss interaction considerations with respect to how readers and future authors of the Journal of Agricultural and Food Chemistry can contribute their expertise toward the extraction and interpretation of chemical information exchanged between agricultural commodities and their associated pests. This holistic, multidisciplinary and thoughtful approach to interactions of plants, insects, and microbes, and the resultant response of the plants, can lead to a better understanding of agricultural ecology, in turn leading to practical and viable solutions to agricultural problems.

Faster Synthesis of Beta-Diketonate Ternary Europium Complexes: Elapsed Times & Reaction Yields

PubMed Central

Lima, Nathalia B. D.; Silva, Anderson I. S.; Gerson, P. C.; Gonçalves, Simone M. C.; Simas, Alfredo M.

2015-01-01

β-diketonates are customary bidentate ligands in highly luminescent ternary europium complexes, such as Eu(β-diketonate)3(L)2, where L stands for a nonionic ligand. Usually, the syntheses of these complexes start by adding, to an europium salt such as EuCl3(H2O)6, three equivalents of β-diketonate ligands to form the complexes Eu(β-diketonate)3(H2O)2. The nonionic ligands are subsequently added to form the target complexes Eu(β-diketonate)3(L)2. However, the Eu(β-diketonate)3(H2O)2 intermediates are frequently both difficult and slow to purify by recrystallization, a step which usually takes a long time, varying from days to several weeks, depending on the chosen β-diketonate. In this article, we advance a novel synthetic technique which does not use Eu(β-diketonate)3(H2O)2 as an intermediate. Instead, we start by adding 4 equivalents of a monodentate nonionic ligand L straight to EuCl3(H2O)6 to form a new intermediate: EuCl3(L)4(H2O)n, with n being either 3 or 4. The advantage is that these intermediates can now be easily, quickly, and efficiently purified. The β-diketonates are then carefully added to this intermediate to form the target complexes Eu(β-diketonate)3(L)2. For the cases studied, the 20-day average elapsed time reduced to 10 days for the faster synthesis, together with an improvement in the overall yield from 42% to 69%. PMID:26710103

Selection of mRNA 5'-untranslated region sequence with high translation efficiency through ribosome display

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mie, Masayasu; Shimizu, Shun; Takahashi, Fumio

2008-08-15

The 5'-untranslated region (5'-UTR) of mRNAs functions as a translation enhancer, promoting translation efficiency. Many in vitro translation systems exhibit a reduced efficiency in protein translation due to decreased translation initiation. The use of a 5'-UTR sequence with high translation efficiency greatly enhances protein production in these systems. In this study, we have developed an in vitro selection system that favors 5'-UTRs with high translation efficiency using a ribosome display technique. A 5'-UTR random library, comprised of 5'-UTRs tagged with a His-tag and Renilla luciferase (R-luc) fusion, were in vitro translated in rabbit reticulocytes. By limiting the translation period, onlymore » mRNAs with high translation efficiency were translated. During translation, mRNA, ribosome and translated R-luc with His-tag formed ternary complexes. They were collected with translated His-tag using Ni-particles. Extracted mRNA from ternary complex was amplified using RT-PCR and sequenced. Finally, 5'-UTR with high translation efficiency was obtained from random 5'-UTR library.« less

Ternary liquid mixtures control the multiplicity, shape and internal structure of emulsion droplets

NASA Astrophysics Data System (ADS)

Haase, Martin F.; Brujic, Jasna

2014-03-01

It is important to control the shape, internal structure and stability of emulsion droplets for drug delivery, biochemical assays, and the design of materials with novel physical properties. Successful methods involve the mechanical manipulation of the flow of oil in water using complex microfluidic devices to make multiple emulsions with a sequential introduction of specific reactants. Instead, here we show how the thermodynamics of immiscible liquid mixtures tailor emulsions using a single dripping instability. For example, the initial composition and choice of surfactant govern the multiplicity of concentric alternating oil and water layers inside the droplets. Stabilizing ternary droplets using nanoparticles gives rise to a plethora of shapes whose geometry is defined by the deformability of the shell and the flow rate. Another option is to incorporate lipids to the multiple emulsion droplet, which form vesicles upon expulsion of the inner water droplets. Depending on the number of initial water droplets, these vesicles eventually form complex hollow topologies, which can be used as junctions or scaffolds for the self-assembly of colloidal particles in the future.

Charge-transfer modified embedded atom method dynamic charge potential for Li-Co-O system

NASA Astrophysics Data System (ADS)

Kong, Fantai; Longo, Roberto C.; Liang, Chaoping; Nie, Yifan; Zheng, Yongping; Zhang, Chenxi; Cho, Kyeongjae

2017-11-01

To overcome the limitation of conventional fixed charge potential methods for the study of Li-ion battery cathode materials, a dynamic charge potential method, charge-transfer modified embedded atom method (CT-MEAM), has been developed and applied to the Li-Co-O ternary system. The accuracy of the potential has been tested and validated by reproducing a variety of structural and electrochemical properties of LiCoO2. A detailed analysis on the local charge distribution confirmed the capability of this potential for dynamic charge modeling. The transferability of the potential is also demonstrated by its reliability in describing Li-rich Li2CoO2 and Li-deficient LiCo2O4 compounds, including their phase stability, equilibrium volume, charge states and cathode voltages. These results demonstrate that the CT-MEAM dynamic charge potential could help to overcome the challenge of modeling complex ternary transition metal oxides. This work can promote molecular dynamics studies of Li ion cathode materials and other important transition metal oxides systems that involve complex electrochemical and catalytic reactions.

Charge-transfer modified embedded atom method dynamic charge potential for Li-Co-O system.

PubMed

Kong, Fantai; Longo, Roberto C; Liang, Chaoping; Nie, Yifan; Zheng, Yongping; Zhang, Chenxi; Cho, Kyeongjae

2017-11-29

To overcome the limitation of conventional fixed charge potential methods for the study of Li-ion battery cathode materials, a dynamic charge potential method, charge-transfer modified embedded atom method (CT-MEAM), has been developed and applied to the Li-Co-O ternary system. The accuracy of the potential has been tested and validated by reproducing a variety of structural and electrochemical properties of LiCoO 2 . A detailed analysis on the local charge distribution confirmed the capability of this potential for dynamic charge modeling. The transferability of the potential is also demonstrated by its reliability in describing Li-rich Li 2 CoO 2 and Li-deficient LiCo 2 O 4 compounds, including their phase stability, equilibrium volume, charge states and cathode voltages. These results demonstrate that the CT-MEAM dynamic charge potential could help to overcome the challenge of modeling complex ternary transition metal oxides. This work can promote molecular dynamics studies of Li ion cathode materials and other important transition metal oxides systems that involve complex electrochemical and catalytic reactions.

Solubility Limits in Lennard-Jones Mixtures: Effects of Disparate Molecule Geometries.

PubMed

Dyer, Kippi M; Perkyns, John S; Pettitt, B Montgomery

2015-07-23

In order to better understand general effects of the size and energy disparities between macromolecules and solvent molecules in solution, especially for macromolecular constructs self-assembled from smaller molecules, we use the first- and second-order exact bridge diagram extensions of the HNC integral equation theory to investigate single-component, binary, ternary, and quaternary mixtures of Lennard-Jones fluids. For pure fluids, we find that the HNCH3 bridge function integral equation (i.e., exact to third order in density) is necessary to quantitatively predict the pure gas and pure liquid sides of the coexistence region of the phase diagram of the Lennard-Jones fluid. For the mixtures, we find that the HNCH2 bridge function integral equation is sufficient to qualitatively predict solubility in the binary, ternary, and quaternary mixtures, up to the nominal solubility limit. The results, as limiting cases, should be useful to several problems, including accurate phase diagram predictions for complex mixtures, design of self-assembling nanostructures via solvent controls, and the solvent contributions to the conformational behavior of macromolecules in complex fluids.

Crystal Structure of the Ternary Complex of a NaV C-Terminal Domain, a Fibroblast Growth Factor Homologous Factor, and Calmodulin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chaojian; Chung, Ben C.; Yan, Haidun

2012-11-13

Voltage-gated Na{sup +} (Na{sub V}) channels initiate neuronal action potentials. Na{sub V} channels are composed of a transmembrane domain responsible for voltage-dependent Na{sup +} conduction and a cytosolic C-terminal domain (CTD) that regulates channel function through interactions with many auxiliary proteins, including fibroblast growth factor homologous factors (FHFs) and calmodulin (CaM). Most ion channel structural studies have focused on mechanisms of permeation and voltage-dependent gating but less is known about how intracellular domains modulate channel function. Here we report the crystal structure of the ternary complex of a human NaV CTD, an FHF, and Ca{sup 2+}-free CaM at 2.2 {angstrom}.more » Combined with functional experiments based on structural insights, we present a platform for understanding the roles of these auxiliary proteins in NaV channel regulation and the molecular basis of mutations that lead to neuronal and cardiac diseases. Furthermore, we identify a critical interaction that contributes to the specificity of individual NaV CTD isoforms for distinctive FHFs.« less

Energy level engineering in ternary organic solar cells: Evaluating exciton dissociation at organic semiconductor interfaces

NASA Astrophysics Data System (ADS)

Feron, Krishna; Thameel, Mahir N.; Al-Mudhaffer, Mohammed F.; Zhou, Xiaojing; Belcher, Warwick J.; Fell, Christopher J.; Dastoor, Paul C.

2017-03-01

Electronic energy level engineering, with the aim to improve the power conversion efficiency in ternary organic solar cells, is a complex problem since multiple charge transfer steps and exciton dissociation driving forces must be considered. Here, we examine exciton dissociation in the ternary system poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester:2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (P3HT:PCBM:DIBSq). Even though the energy level diagram suggests that exciton dissociation at the P3HT:DIBSq interface should be efficient, electron paramagnetic resonance and external quantum efficiency measurements of planar devices show that this interface is not capable of generating separated charge carriers. Efficient exciton dissociation is still realised via energy transfer, which transports excitons from the P3HT:DIBSq interface to the DIBSq:PCBM interface, where separated charge carriers can be generated efficiently. This work demonstrates that energy level diagrams alone cannot be relied upon to predict the exciton dissociation and charge separation capability of an organic semiconductor interface and that energy transfer relaxes the energy level constraints for optimised multi-component organic solar cells.

Spatial Associations and Chemical Composition of Organic Carbon Sequestered in Fe, Ca, and Organic Carbon Ternary Systems.

PubMed

Sowers, Tyler D; Adhikari, Dinesh; Wang, Jian; Yang, Yu; Sparks, Donald L

2018-05-25

Organo-mineral associations of organic carbon (OC) with iron (Fe) oxides play a major role in environmental OC sequestration, a process crucial to mitigating climate change. Calcium has been found to have high coassociation with OC in soils containing high Fe content, increase OC sorption extent to poorly crystalline Fe oxides, and has long been suspected to form bridging complexes with Fe and OC. Due to the growing realization that Ca may be an important component of C cycling, we launched a scanning transmission X-ray microscopy (STXM) investigation, paired with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, in order to spatially resolve Fe, Ca, and OC relationships and probe the effect of Ca on sorbed OC speciation. We performed STXM-NEXAFS analysis on 2-line ferrihydrite reacted with leaf litter-extractable dissolved OC and citric acid in the absence and presence of Ca. Organic carbon was found to highly associate with Ca ( R 2 = 0.91). Carboxylic acid moieties were dominantly sequestered; however, Ca facilitated the additional sequestration of aromatic and phenolic moieties. Also, C NEXAFS revealed polyvalent metal ion complexation. Our results provide evidence for the presence of Fe-Ca-OC ternary complexation, which has the potential to significantly impact how organo-mineral associations are modeled.

Structural analysis of fungus-derived FAD glucose dehydrogenase

PubMed Central

Yoshida, Hiromi; Sakai, Genki; Mori, Kazushige; Kojima, Katsuhiro; Kamitori, Shigehiro; Sode, Koji

2015-01-01

We report the first three-dimensional structure of fungus-derived glucose dehydrogenase using flavin adenine dinucleotide (FAD) as the cofactor. This is currently the most advanced and popular enzyme used in glucose sensor strips manufactured for glycemic control by diabetic patients. We prepared recombinant nonglycosylated FAD-dependent glucose dehydrogenase (FADGDH) derived from Aspergillus flavus (AfGDH) and obtained the X-ray structures of the binary complex of enzyme and reduced FAD at a resolution of 1.78 Å and the ternary complex with reduced FAD and D-glucono-1,5-lactone (LGC) at a resolution of 1.57 Å. The overall structure is similar to that of fungal glucose oxidases (GOxs) reported till date. The ternary complex with reduced FAD and LGC revealed the residues recognizing the substrate. His505 and His548 were subjected for site-directed mutagenesis studies, and these two residues were revealed to form the catalytic pair, as those conserved in GOxs. The absence of residues that recognize the sixth hydroxyl group of the glucose of AfGDH, and the presence of significant cavity around the active site may account for this enzyme activity toward xylose. The structural information will contribute to the further engineering of FADGDH for use in more reliable and economical biosensing technology for diabetes management. PMID:26311535

Determination for Enterobacter cloacae based on a europium ternary complex labeled DNA probe

NASA Astrophysics Data System (ADS)

He, Hui; Niu, Cheng-Gang; Zeng, Guang-Ming; Ruan, Min; Qin, Pin-Zhu; Liu, Jing

2011-11-01

The fast detection and accurate diagnosis of the prevalent pathogenic bacteria is very important for the treatment of disease. Nowadays, fluorescence techniques are important tools for diagnosis. A two-probe tandem DNA hybridization assay was designed for the detection of Enterobacter cloacae based on time-resolved fluorescence. In this work, the authors synthesized a novel europium ternary complex Eu(TTA) 3(5-NH 2-phen) with intense luminescence, high fluorescence quantum yield and long lifetime before. We developed a method based on this europium complex for the specific detection of original extracted DNA from E. cloacae. In the hybridization assay format, the reporter probe was labeled with Eu(TTA) 3(5-NH 2-phen) on the 5'-terminus, and the capture probe capture probe was covalent immobilized on the surface of the glutaraldehyde treated glass slides. The original extracted DNA of samples was directly used without any DNA purification and amplification. The detection was conducted by monitoring the fluorescence intensity from the glass surface after DNA hybridization. The detection limit of the DNA was 5 × 10 -10 mol L -1. The results of the present work proved that this new approach was easy to operate with high sensitivity and specificity. It could be conducted as a powerful tool for the detection of pathogen microorganisms in the environment.

Tropomyosin modulates erythrocyte membrane stability

PubMed Central

An, Xiuli; Salomao, Marcela; Guo, Xinhua; Gratzer, Walter; Mohandas, Narla

2007-01-01

The ternary complex of spectrin, actin, and 4.1R (human erythrocyte protein 4.1) defines the nodes of the erythrocyte membrane skeletal network and is inseparable from membrane stability under mechanical stress. These junctions also contain tropomyosin (TM) and the other actin-binding proteins, adducin, protein 4.9, tropomodulin, and a small proportion of capZ, the functions of which are poorly defined. Here, we have examined the consequences of selective elimination of TM from the membrane. We have shown that the mechanical stability of the membranes of resealed ghosts devoid of TM is grossly, but reversibly, impaired. That the decreased membrane stability of TM-depleted membranes is the result of destabilization of the ternary complex of the network junctions is demonstrated by the strongly facilitated entry into the junctions in situ of a β-spectrin peptide, containing the actin- and 4.1R-binding sites, after extraction of the TM. The stabilizing effect of TM is highly specific, in that it is only the endogenous isotype, and not the slightly longer muscle TM that can bind to the depleted membranes and restore their mechanical stability. These findings have enabled us identify a function for TM in elevating the mechanical stability of erythrocyte membranes by stabilizing the spectrin-actin-4.1R junctional complex. PMID:17008534

The three-dimensional structure of the native ternary complex of bovine pancreatic procarboxypeptidase A with proproteinase E and chymotrypsinogen C.

PubMed Central

Gomis-Rüth, F X; Gómez, M; Bode, W; Huber, R; Avilés, F X

1995-01-01

The metalloexozymogen procarboxypeptidase A is mainly secreted in ruminants as a ternary complex with zymogens of two serine endoproteinases, chymotrypsinogen C and proproteinase E. The bovine complex has been crystallized, and its molecular structure analysed and refined at 2.6 A resolution to an R factor of 0.198. In this heterotrimer, the activation segment of procarboxypeptidase A essentially clamps the other two subunits, which shield the activation sites of the former from tryptic attack. In contrast, the propeptides of both serine proproteinases are freely accessible to trypsin. This arrangement explains the sequential and delayed activation of the constituent zymogens. Procarboxypeptidase A is virtually identical to the homologous monomeric porcine form. Chymotrypsinogen C displays structural features characteristic for chymotrypsins as well as elastases, except for its activation domain; similar to bovine chymotrypsinogen A, its binding site is not properly formed, while its surface located activation segment is disordered. The proproteinase E structure is fully ordered and strikingly similar to active porcine elastase; its specificity pocket is occluded, while the activation segment is fixed to the molecular surface. This first structure of a native zymogen from the proteinase E/elastase family does not fundamentally differ from the serine proproteinases known so far. Images PMID:7556081

Spectroscopic identification of binary and ternary surface complexes of Np(V) on gibbsite.

PubMed

Gückel, Katharina; Rossberg, André; Müller, Katharina; Brendler, Vinzenz; Bernhard, Gert; Foerstendorf, Harald

2013-12-17

For the first time, detailed molecular information on the Np(V) sorption species on amorphous Al(OH)3 and crystalline gibbsite was obtained by in situ time-resolved Attenuated Total Reflection Fourier-Transform Infrared (ATR FT-IR) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. The results consistently demonstrate the formation of mononuclear inner sphere complexes of the NpO2(+) ion irrespective of the prevailing atmospheric condition. The impact of the presence of atmospheric equivalent added carbonate on the speciation in solution and on the surfaces becomes evident from vibrational data. While the 1:1 aqueous carbonato species (NpO2CO3(-)) was found to become predominant in the circumneutral pH range, it is most likely that this species is sorbed onto the gibbsite surface as a ternary inner sphere surface complex where the NpO2(+) moiety is directly coordinated to the functional groups of the gibbsite's surface. These findings are corroborated by results obtained from EXAFS spectroscopy providing further evidence for a bidentate coordination of the Np(V) ion on amorphous Al(OH)3. The identification of the Np(V) surface species on gibbsite constitutes a basic finding for a comprehensive description of the dissemination of neptunium in groundwater systems.

Petrologic and zircon U-Pb geochronological characteristics of the pelitic granulites from the Badu Complex of the Cathaysia Block, South China

NASA Astrophysics Data System (ADS)

Zhao, Lei; Zhou, Xiwen; Zhai, Mingguo; Liu, Bo; Cui, Xiahong

2018-06-01

The recognition of the Indosinian Orogeny in the South China block has been controversial and difficult because of strong weathering and thick cover. High temperature (HT) and high pressure (HP) metamorphic rocks related to this orogeny were considered to be absent from this orogenic belt until the recent discovery of eclogite and granulite facies meta-igneous rocks, occurring as lenses within the meta-sedimentary rocks of the Badu Complex. However, metamorphic state of these meta-sedimentary rocks is still not clear. Besides, there have been no geochronological data of HT pelitic granulites previously reported from the Badu Complex. This paper presents petrographic characteristics and zircon geochronological results on the newly discovered kyanite garnet gneiss, pyroxene garnet gneiss and the HT pelitic granulites (sillimanite garnet gneiss). Mineral assemblages are garnet + sillimanite + ternary feldspar + plagioclase + quartz + biotite for the HT pelitic granulite, kyanite + ternary feldspar + garnet + sillimanite + plagioclase + quartz + biotite for the kyanite garnet gneiss, and garnet + biotite + pyroxene + plagioclase + ternary feldspar + quartz for the pyroxene garnet gneiss, respectively. Decompressional coronas around garnet grains can be observed in all these pelitic rocks. Typical granulite facies mineral assemblages and reaction textures suggest that these rocks experienced HP granulite facies metamorphism and overprinted decompression along a clockwise P-T loop. Results from integrated U-Pb dating and REE analysis indicate the growth of metamorphic zircons from depleted heavy REE sources (100-50 chondrite) compared with detrital zircons derived from granitic sources (typically > 1000 chondrite). Metamorphic zircons in HP granulite exhibit no or subdued negative Eu anomalies, which perhaps indicate zircon overgrowth under eclogite facies conditions. The zircon overgrowth ages range from 250 to 235 Ma, suggesting that HP granulite (eclogite) to granulite facies metamorphism of these supracrustal rocks occurred in the Early-Middle Triassic. Based on the presence of HP granulite facies pelitic rocks, it is inferred that significant underthrusting was involved during the Indosinian Orogeny which introduced these supracrustal rocks to lower crustal levels.

Colloid, adhesive and release properties of nanoparticular ternary complexes between cationic and anionic polysaccharides and basic proteins like bone morphogenetic protein BMP-2.

PubMed

Petzold, R; Vehlow, D; Urban, B; Grab, A L; Cavalcanti-Adam, E A; Alt, V; Müller, M

2017-03-01

Herein we describe an interfacial local drug delivery system for bone morphogenetic protein 2 (BMP-2) based on coatings of polyelectrolyte complex (PEC) nanoparticles (NP). The application horizon is the functionalization of bone substituting materials (BSM) used for the therapy of systemic bone diseases. Nanoparticular ternary complexes of cationic and anionic polysaccharides and BMP-2 or two further model proteins, respectively, were prepared in dependence of the molar mixing ratio, pH value and of the cationic polysaccharide. As further proteins chymotrypsin (CHY) and papain (PAP) were selected, which served as model proteins for BMP-2 due to similar isoelectric points and molecular weights. As charged polysaccharides ethylenediamine modified cellulose (EDAC) and trimethylammonium modified cellulose (PQ10) were combined with cellulose sulphatesulfate (CS). Mixing diluted cationic and anionic polysaccharide and protein solutions according to a slight either anionic or cationic excess charge colloidal ternary dispersions formed, which were cast onto germanium model substrates by water evaporation. Dynamic light scattering (DLS) demonstrated, that these dispersions were colloidally stable for at least one week. Fourier Transform Infrared (FTIR) showed, that the cast protein loaded PEC NP coatings were irreversibly adhesive at the model substrate in contact to HEPES buffer and solely CHY, PAP and BMP-2 were released within long-term time scale. Advantageously, out of the three proteins BMP-2 showed the smallest initial burst and the slowest release kinetics and around 25% of the initial BMP-2 content were released within 14days. Released BMP-2 showed significant activity in the myoblast cells indicating the ability to regulate the formation of new bone. Therefore, BMP-2 loaded PEC NP are suggested as novel promising tool for the functionalization of BSM used for the therapy of systemic bone diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

Immunohistochemical localization of DPP10 in rat brain supports the existence of a Kv4/KChIP/DPPL ternary complex in neurons.

PubMed

Wang, Wan-Chen; Cheng, Chau-Fu; Tsaur, Meei-Ling

2015-03-01

Subthreshold A-type K(+) currents (ISA s) have been recorded from the cell bodies of hippocampal and neocortical interneurons as well as neocortical pyramidal neurons. Kv4 channels are responsible for the somatodendritic ISA s. It has been proposed that neuronal Kv4 channels are ternary complexes including pore-forming Kv4 subunits, K(+) channel-interacting proteins (KChIPs), and dipeptidyl peptidase-like proteins (DPPLs). However, colocalization evidence was still lacking. The distribution of DPP10 mRNA in rodent brain has been reported but its protein localization remains unknown. In this study, we generated a DPP10 antibody to label DPP10 protein in adult rat brain by immunohistochemistry. Absent from glia, DPP10 proteins appear mainly in the cell bodies of DPP10(+) neurons, not only at the plasma membrane but also in the cytoplasm. At least 6.4% of inhibitory interneurons in the hippocampus coexpressed Kv4.3, KChIP1, and DPP10, with the highest density in the CA1 strata alveus/oriens/pyramidale and the dentate hilus. Colocalization of Kv4.3/KChIP1/DPP10 was also detected in at least 6.9% of inhibitory interneurons scattered throughout the neocortex. Both hippocampal and neocortical Kv4.3/KChIP1/DPP10(+) inhibitory interneurons expressed parvalbumin or somatostatin, but not calbindin or calretinin. Furthermore, we found colocalization of Kv4.2/Kv4.3/KChIP3/DPP10 in neocortical layer 5 pyramidal neurons and olfactory bulb mitral cells. Together, although DPP10 is also expressed in some brain neurons lacking Kv4 (such as parvalbumin- and somatostatin-positive Golgi cells in the cerebellum), colocalization of DPP10 with Kv4 and KChIP at the plasma membrane of ISA -expressing neuron somata supports the existence of Kv4/KChIP/DPPL ternary complex in vivo. © 2014 Wiley Periodicals, Inc.

Selective Co-Encapsulation Inside an M6 L4 Cage.

PubMed

Leenders, Stefan H A M; Becker, René; Kumpulainen, Tatu; de Bruin, Bas; Sawada, Tomohisa; Kato, Taito; Fujita, Makoto; Reek, Joost N H

2016-10-17

There is broad interest in molecular encapsulation as such systems can be utilized to stabilize guests, facilitate reactions inside a cavity, or give rise to energy-transfer processes in a confined space. Detailed understanding of encapsulation events is required to facilitate functional molecular encapsulation. In this contribution, it is demonstrated that Ir and Rh-Cp-type metal complexes can be encapsulated inside a self-assembled M 6 L 4 metallocage only in the presence of an aromatic compound as a second guest. The individual guests are not encapsulated, suggesting that only the pair of guests can fill the void of the cage. Hence, selective co-encapsulation is observed. This principle is demonstrated by co-encapsulation of a variety of combinations of metal complexes and aromatic guests, leading to several ternary complexes. These experiments demonstrate that the efficiency of formation of the ternary complexes depends on the individual components. Moreover, selective exchange of the components is possible, leading to formation of the most favorable complex. Besides the obvious size effect, a charge-transfer interaction may also contribute to this effect. Charge-transfer bands are clearly observed by UV/Vis spectrophotometry. A change in the oxidation potential of the encapsulated electron donor also leads to a shift in the charge-transfer energy bands. As expected, metal complexes with a higher oxidation potential give rise to a higher charge-transfer energy and a larger hypsochromic shift in the UV/Vis spectrum. These subtle energy differences may potentially be used to control the binding and reactivity of the complexes bound in a confined space. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Ellipsometric study of metal-organic chemically vapor deposited III-V semiconductor structures

NASA Technical Reports Server (NTRS)

Alterovitz, Samuel A.; Sekula-Moise, Patricia A.; Sieg, Robert M.; Drotos, Mark N.; Bogner, Nancy A.

1992-01-01

An ellipsometric study of MOCVD-grown layers of AlGaAs and InGaAs in thick films and strained layer complex structures is presented. It is concluded that the ternary composition of thick nonstrained layers can be accurately determined to within experimental errors using numerical algorithms. In the case of complex structures, thickness of all layers and the alloy composition of nonstrained layers can be determined simultaneously, provided that the correlations between parameters is no higher than 0.9.

Single-source precursors for ternary chalcopyrite materials, and methods of making and using the same

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K. (Inventor); Hepp, Aloysius F. (Inventor); Harris, Jerry D. (Inventor); Jin, Michael Hyun-Chul (Inventor); Castro, Stephanie L. (Inventor)

2006-01-01

A single source precursor for depositing ternary I-III-VI.sub.2 chalcopyrite materials useful as semiconductors. The single source precursor has the I-III-VI.sub.2 stoichiometry built into a single precursor molecular structure which degrades on heating or pyrolysis to yield the desired I-III-VI.sub.2 ternary chalcopyrite. The single source precursors effectively degrade to yield the ternary chalcopyrite at low temperature, e.g. below 500.degree. C., and are useful to deposit thin film ternary chalcopyrite layers via a spray CVD technique. The ternary single source precursors according to the invention can be used to provide nanocrystallite structures useful as quantum dots. A method of making the ternary single source precursors is also provided.

Effect of phosphate on U(VI) sorption to montmorillonite: Ternary complexation and precipitation barriers

NASA Astrophysics Data System (ADS)

Troyer, Lyndsay D.; Maillot, Fabien; Wang, Zheming; Wang, Zimeng; Mehta, Vrajesh S.; Giammar, Daniel E.; Catalano, Jeffrey G.

2016-02-01

Phosphate addition is a potential treatment method to lower the solubility of U(VI) in soil and groundwater systems by causing U(VI) phosphate precipitation as well as enhancing adsorption. Previous work has shown that iron oxide surfaces may facilitate the nucleation of U(VI) phosphate minerals and, that under weakly acidic conditions, phosphate also enhances U(VI) adsorption to such phases. Like iron oxides, clays are important reactive phases in the subsurface but little is known about the interaction of U(VI) and phosphate with these minerals. The effect of aqueous phosphate on U(VI) binding to Wyoming montmorillonite (SWy-2) in air-equilibrated systems was investigated. Equilibrium U(VI) uptake to montmorillonite was determined at pH 4, 6 and 8 at discrete initial phosphate concentrations between 0 and 100 μM. The observed behavior of U(VI) indicates a transition from adsorption to precipitation with increasing total uranium and phosphate concentrations at all pH values. At the highest phosphate concentration examined at each pH value, a barrier to U(VI) phosphate nucleation is observed. At lower concentrations, phosphate has no effect on macroscopic U(VI) adsorption. To assess the mechanisms of U(VI)-phosphate interactions on smectite surfaces, U(VI) speciation was investigated under selected conditions using laser-induced fluorescence spectroscopy (LIFS) and extended X-ray absorption fine-structure (EXAFS) spectroscopy. Samples above the precipitation threshold display EXAFS and LIFS spectral signatures consistent with the autunite family of U(VI) phosphate minerals. However, at lower U(VI) concentrations, changes in LIFS spectra upon phosphate addition suggest that U(VI)-phosphate ternary surface complexes form on the montmorillonite surface at pH 4 and 6 despite the lack of a macroscopic effect on adsorption. The speciation of solid-associated U(VI) below the precipitation threshold at pH 8 is dominated by U(VI)-carbonate surface complexes. This work reveals that ternary complexation may occur without a macroscopic signature, which is attributed to phosphate not appreciably binding to smectite in the absence of U(VI), with U(VI) surface complexes serving as the sole reactive surface sites for phosphate. This study shows that phosphate does not enhance U(VI) adsorption to smectite clay minerals, unlike oxide phases, and that a barrier to homogeneous nucleation of U(VI) phosphates was not affected by the presence of the smectite surface.

Structural Basis for a Reciprocating Mechanism of Negative Cooperativity in Dimeric Phosphagen Kinase Activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, X.; Ye, S; Guo, S

Phosphagen kinase (PK) family members catalyze the reversible phosphoryl transfer between phosphagen and ADP to reserve or release energy in cell energy metabolism. The structures of classic quaternary complexes of dimeric creatine kinase (CK) revealed asymmetric ligand binding states of two protomers, but the significance and mechanism remain unclear. To understand this negative cooperativity further, we determined the first structure of dimeric arginine kinase (dAK), another PK family member, at 1.75 {angstrom}, as well as the structure of its ternary complex with AMPPNP and arginine. Further structural analysis shows that the ligand-free protomer in a ligand-bound dimer opens more widelymore » than the protomers in a ligand-free dimer, which leads to three different states of a dAK protomer. The unexpected allostery of the ligand-free protomer in a ligand-bound dimer should be relayed from the ligand-binding-induced allostery of its adjacent protomer. Mutations that weaken the interprotomer connections dramatically reduced the catalytic activities of dAK, indicating the importance of the allosteric propagation mediated by the homodimer interface. These results suggest a reciprocating mechanism of dimeric PK, which is shared by other ATP related oligomeric enzymes, e.g., ATP synthase. - Wu, X., Ye, S., Guo, S., Yan, W., Bartlam, M., Rao, Z. Structural basis for a reciprocating mechanism of negative cooperativity in dimeric phosphagen kinase activity.« less

Structural and Biochemical Studies on ATP Binding and Hydrolysis by the Escherichia coli RNA Chaperone Hfq

PubMed Central

Večerek, Branislav; Rajkowitsch, Lukas; Carugo, Oliviero; Djinović-Carugo, Kristina; Bläsi, Udo

2012-01-01

In Escherichia coli the RNA chaperone Hfq is involved in riboregulation by assisting base-pairing between small regulatory RNAs (sRNAs) and mRNA targets. Several structural and biochemical studies revealed RNA binding sites on either surface of the donut shaped Hfq-hexamer. Whereas sRNAs are believed to contact preferentially the YKH motifs present on the proximal site, poly(A)15 and ADP were shown to bind to tripartite binding motifs (ARE) circularly positioned on the distal site. Hfq has been reported to bind and to hydrolyze ATP. Here, we present the crystal structure of a C-terminally truncated variant of E. coli Hfq (Hfq65) in complex with ATP, showing that it binds to the distal R-sites. In addition, we revisited the reported ATPase activity of full length Hfq purified to homogeneity. At variance with previous reports, no ATPase activity was observed for Hfq. In addition, FRET assays neither indicated an impact of ATP on annealing of two model oligoribonucleotides nor did the presence of ATP induce strand displacement. Moreover, ATP did not lead to destabilization of binary and ternary Hfq-RNA complexes, unless a vast stoichiometric excess of ATP was used. Taken together, these studies strongly suggest that ATP is dispensable for and does not interfere with Hfq-mediated RNA transactions. PMID:23226421

Derivatization of DNAs with Selenium at 6-Position of Guanine for Function and Crystal Structure Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salon, J.; Jiang, J; Sheng, J

2008-01-01

To investigate nucleic acid base pairing and stacking via atom-specific mutagenesis and crystallography, we have synthesized for the first time the 6-Se-deoxyguanosine phosphoramidite and incorporated it into DNAs via solid-phase synthesis with a coupling yield over 97%. We found that the UV absorption of the Se-DNAs red-shifts over 100 nm to 360 nm ({Epsilon} = 2.3 x 10{sup 4} M{sup -1} cm{sup -1}), the Se-DNAs are yellow colored, and this Se modification is relatively stable in water and at elevated temperature. Moreover, we successfully crystallized a ternary complex of the Se-G-DNA, RNA and RNase H. The crystal structure determination andmore » analysis reveal that the overall structures of the native and Se-modified nucleic acid duplexes are very similar, the selenium atom participates in a Se-mediated hydrogen bond (Se H-N), and the {sup Se}G and C form a base pair similar to the natural G-C pair though the Se-modification causes the base-pair to shift (approximately 0.3 {angstrom}). Our biophysical and structural studies provide new insights into the nucleic acid flexibility, duplex recognition and stability. Furthermore, this novel selenium modification of nucleic acids can be used to investigate chemogenetics and structure of nucleic acids and their protein complexes.« less

Structure and luminescent property of complexes of aryl carboxylic acid-functionalized polystyrene with Eu(III) and Tb(III) ions.

PubMed

Gao, Baojiao; Shi, Nan; Qiao, Zongwen

2015-11-05

Via polymer reactions, naphthoic acid (NA) and benzoic acid (BA) were bonded onto the side chains of polystyrene (PS), respectively, and two aryl carboxylic acid-functionalized polystyrenes, PSNA and PSBA, were obtained. Using PSNA and PSBA as macromolecule ligands and Eu(3+) and Tb(3+) ions as central ions, various luminescent binary polymer-rare earth complexes were prepared. At the same time, with 1,10-phenanthroline (Phen) and 4,4'-bipyridine (Bipy) as small-molecule co-ligands, various ternary polymer-rare earth complexes were also prepared. On the basis of characterizing PSNA, PSBA and complexes, the relationship between structure and luminescent property for these prepared complexes were mainly investigated. The study results show that the macromolecule ligands PSNA and PSBA, or the bonded NA and BA ligands, can strongly sensitize the fluorescence emissions of Eu(3+) ion or Tb(3+) ion, but the sensitization effect is strongly dependent on the structure of the ligands and the property of the central ions, namely it is strongly dependent on the matching degree of energy levels. The fluorescence emission of the binary complex PS-(NA)3-Eu(III) is stronger than that PS-(BA)3-Eu(III), indicating ligand NA has stronger sensitization action for Eu(3+) ion than ligand BA; the binary complex PS-(BA)3-Tb(III) emit strong characteristic fluorescence of Tb(3+) ion, displaying that ligand BA can strongly sensitize Tb(3+) ion, whereas the binary complex PS-(NA)3-Tb(III) nearly does not emit the characteristic fluorescence of Tb(3+) ion, showing that ligand NA does not sensitize Tb(3+) ion. The fluorescence intensity of the ternary complexes is much stronger than that of the binary complexes in the same series. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis and luminescence properties of polymer-rare earth complexes containing salicylaldehyde-type bidentate Schiff base ligand.

PubMed

Zhang, Dandan; Gao, Baojiao; Li, Yanbin

2017-08-01

Using molecular design and polymer reactions, two types of bidentate Schiff base ligands, salicylaldehyde-aniline (SAN) and salicylaldehyde-cyclohexylamine (SCA), were synchronously synthesized and bonded onto the side chain of polysulfone (PSF), giving two bidentate Schiff base ligand-functionalized PSFs, PSF-SAN and PSF-SCA, referred to as macromolecular ligands. Following coordination reactions between the macromolecular ligands and Eu(III) and Tb(III) ions (the reaction occurred between the bonded ligands SAN or SCA and the lanthanide ion), two series of luminescent polymer-rare earth complexes, PSF-SAN-Eu(III) and PSF-SCA-Tb(III), were obtained. The two macromolecular ligands were fully characterized by Fourier transform infrared (FTIR), 1 H NMR and UV absorption spectroscopy, and the prepared complexes were also characterized by FTIR, UV absorption spectroscopy and thermo-gravity analysis. On this basis, the photoluminescence properties of these complexes and the relationships between their structure and luminescence were investigated in depth. The results show that the bonded bidentate Schiff base ligands, SAN and SCA, can effectively sensitize the fluorescence emission of Eu(III) and Tb(III) ions, respectively. PSF-SAN-Eu(III) series complexes, namely the binary complex PSF-(SAN) 3 -Eu(III) and the ternary complex PSF-(SAN) 3 -Eu(III)-(Phen) 1 (Phen is the small-molecule ligand 1,10-phenanthroline), produce strong red luminescence, suggesting that the triplet state energy level of SAN is lower and well matched with the resonant energy level of the Eu(III) ion. By contrast, PSF-SAN-Eu(III) series complexes, namely the binary complex PSF-(SCA) 3 -Tb(III) and the ternary complex PSF-(SCA) 3 -Tb(III)-(Phen) 1 , display strong green luminescence, suggesting that the triplet state energy level of SCA is higher and is well matched with the resonant energy level of Tb(III). Copyright © 2017 John Wiley & Sons, Ltd.

IUPAC-NIST Solubility Data Series. 100. Rare Earth Metal Fluorides in Water and Aqueous Systems. Part 1. Scandium Group (Sc, Y, La)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mioduski, Tomasz; Gumiński, Cezary, E-mail: cegie@chem.uw.edu.pl; Zeng, Dewen, E-mail: dewen-zeng@hotmail.com

2014-03-15

This work presents an assessment of solubility data for rare earth metal fluorides (generally of trivalent metals and of CeF{sub 4}) in water and in aqueous ternary systems. Compilations of all available experimental data are introduced for each rare earth metal fluoride with a corresponding critical evaluation. Every such evaluation contains a collection of all solubility results in water, a selection of suggested solubility data, and a brief discussion of the multicomponent systems. Because the ternary systems were seldom studied more than once, no critical evaluations of such data were possible. Only simple fluorides (no complexes or binary salts) aremore » treated as the input substances in this report. The literature has been covered through the end of 2013.« less

Ternary complexes of Zn(II) and Cu(II) with 1-((2-hydroxynaphthalen-1-yl)methylene)-4-phenylthiosemicarbazide in the presence of heterocyclic bases as auxiliary ligands: Synthesis, spectroscopic and structural characterization and antibacterial activity

NASA Astrophysics Data System (ADS)

Azarkish, Mohammad; Akbari, Alireza; Sedaghat, Tahereh; Simpson, Jim

2018-03-01

The new ternary complexes, ZnLL‧ [L = 1-((2-hydroxynaphthalen-1-yl)methylene)-4-phenylthiosemicarbazide and L‧ = imidazole (1), 2, 2‧-bipyridine (2) and 2-methyimidazole (3)], Zn2L2L‧ [L‧ = 4, 4‧-bipy (4)] and CuLL‧ [L‧ = 2, 2‧-bipy (5)] have been synthesized by the reaction of a metal(II) acetate salt with the thiosemicarbazone and in presence of heterocyclic bases as auxiliary ligands. The synthesized compounds were investigated by elemental analysis and IR, 1H NMR, and 13C NMR spectroscopy and complex 5 was structurally characterized by X-ray crystallography. The results indicate the thiosemicarbazone doubly deprotonated and coordinates to metal through the thiolate sulfur, imine nitrogen and phenolic oxygen atoms. The nitrogen atom(s) of the auxiliary ligand complete the coordination sphere. Complex 4 is binuclear with 4, 4‧-bipy acting as a bridging ligand. The structure of 5 is a distorted square pyramid with one of the bipyridine nitrogen atoms in the apical position. This compound creates an inversion dimer in solid state by intermolecular hydrogen bonds of Nsbnd H⋯S type. The in vitro antibacterial activity of the synthesized compounds were evaluated against Gram-positive (B. subtilis and S. aureus) and Gram-negative (P. aeruginosa) bacteria and is compared to that of standard antibacterial drugs. All complexes exhibit good inhibitory effects and are significantly more effective than the parent ligand.

Viral RNAi suppressor reversibly binds siRNA to outcompete Dicer and RISC via multiple-turnover

PubMed Central

Rawlings, Renata A.; Krishnan, Vishalakshi; Walter, Nils G.

2011-01-01

RNA interference (RNAi) is a conserved gene regulatory mechanism employed by most eukaryotes as a key component of their innate immune response against viruses and retrotransposons. During viral infection, the RNase III-type endonuclease Dicer cleaves viral double-stranded RNA into small interfering RNAs (siRNAs), 21–24 nucleotides in length, and helps load them into the RNA-induced silencing complex (RISC) to guide cleavage of complementary viral RNA. As a countermeasure, many viruses have evolved viral RNA silencing suppressor (RSS) proteins that tightly, and presumably quantitatively, bind siRNAs to thwart RNAi-mediated degradation. Viral RSS proteins also act across kingdoms as potential immunosuppressors in gene therapeutic applications. Here we report fluorescence quenching and electrophoretic mobility shift assays that probe siRNA binding by the dimeric RSS p19 from Carnation Italian Ringspot Virus (CIRV), as well as by human Dicer and RISC assembly complexes. We find that the siRNA:p19 interaction is readily reversible, characterized by rapid binding ((1.69 ± 0.07)×108 M−1s−1) and marked dissociation (koff = 0.062 ± 0.002 s−1). We also observe that p19 efficiently competes with recombinant Dicer and inhibits formation of RISC-related assembly complexes found in human cell extract. Computational modeling based on these results provides evidence for the transient formation of a ternary complex between siRNA, human Dicer, and p19. An expanded model of RNA silencing indicates that multiple-turnover by reversible binding of siRNAs potentiates the efficiency of the suppressor protein. Our predictive model is expected to be applicable to the dosing of p19 as a silencing suppressor in viral gene therapy. PMID:21354178

Viral RNAi suppressor reversibly binds siRNA to outcompete Dicer and RISC via multiple turnover.

PubMed

Rawlings, Renata A; Krishnan, Vishalakshi; Walter, Nils G

2011-04-29

RNA interference is a conserved gene regulatory mechanism employed by most eukaryotes as a key component of their innate immune response to viruses and retrotransposons. During viral infection, the RNase-III-type endonuclease Dicer cleaves viral double-stranded RNA into small interfering RNAs (siRNAs) 21-24 nucleotides in length and helps load them into the RNA-induced silencing complex (RISC) to guide the cleavage of complementary viral RNA. As a countermeasure, many viruses have evolved viral RNA silencing suppressors (RSS) that tightly, and presumably quantitatively, bind siRNAs to thwart RNA-interference-mediated degradation. Viral RSS proteins also act across kingdoms as potential immunosuppressors in gene therapeutic applications. Here we report fluorescence quenching and electrophoretic mobility shift assays that probe siRNA binding by the dimeric RSS p19 from Carnation Italian Ringspot Virus, as well as by human Dicer and RISC assembly complexes. We find that the siRNA:p19 interaction is readily reversible, characterized by rapid binding [(1.69 ± 0.07) × 10(8) M(-)(1) s(-1)] and marked dissociation (k(off)=0.062 ± 0.002 s(-1)). We also observe that p19 efficiently competes with recombinant Dicer and inhibits the formation of RISC-related assembly complexes found in human cell extract. Computational modeling based on these results provides evidence for the transient formation of a ternary complex between siRNA, human Dicer, and p19. An expanded model of RNA silencing indicates that multiple turnover by reversible binding of siRNAs potentiates the efficiency of the suppressor protein. Our predictive model is expected to be applicable to the dosing of p19 as a silencing suppressor in viral gene therapy. Copyright © 2011 Elsevier Ltd. All rights reserved.

Molecular interactions involved in the transactivation of the human T-cell leukemia virus type 1 promoter mediated by Tax and CREB-2 (ATF-4).

PubMed

Gachon, F; Thebault, S; Peleraux, A; Devaux, C; Mesnard, J M

2000-05-01

The human T-cell leukemia virus type 1 (HTLV-1) Tax protein activates viral transcription through three 21-bp repeats located in the U3 region of the HTLV-1 long terminal repeat and called Tax-responsive elements (TxREs). Each TxRE contains nucleotide sequences corresponding to imperfect cyclic AMP response elements (CRE). In this study, we demonstrate that the bZIP transcriptional factor CREB-2 is able to bind in vitro to the TxREs and that CREB-2 binding to each of the 21-bp motifs is enhanced by Tax. We also demonstrate that Tax can weakly interact with CREB-2 bound to a cellular palindromic CRE motif such as that found in the somatostatin promoter. Mutagenesis of Tax and CREB-2 demonstrates that both N- and C-terminal domains of Tax and the C-terminal region of CREB-2 are required for direct interaction between the two proteins. In addition, the Tax mutant M47, defective for HTLV-1 activation, is unable to form in vitro a ternary complex with CREB-2 and TxRE. In agreement with recent results suggesting that Tax can recruit the coactivator CREB-binding protein (CBP) on the HTLV-1 promoter, we provide evidence that Tax, CREB-2, and CBP are capable of cooperating to stimulate viral transcription. Taken together, our data highlight the major role played by CREB-2 in Tax-mediated transactivation.

Integration of anteroposterior and dorsoventral regulation of Phox2b transcription in cranial motoneuron progenitors by homeodomain proteins.

PubMed

Samad, Omar Abdel; Geisen, Marc J; Caronia, Giuliana; Varlet, Isabelle; Zappavigna, Vincenzo; Ericson, Johan; Goridis, Christo; Rijli, Filippo M

2004-08-01

Little is known about the molecular mechanisms that integrate anteroposterior (AP) and dorsoventral (DV) positional information in neural progenitors that specify distinct neuronal types within the vertebrate neural tube. We have previously shown that in ventral rhombomere (r)4 of Hoxb1 and Hoxb2 mutant mouse embryos, Phox2b expression is not properly maintained in the visceral motoneuron progenitor domain (pMNv), resulting in a switch to serotonergic fate. Here, we show that Phox2b is a direct target of Hoxb1 and Hoxb2. We found a highly conserved Phox2b proximal enhancer that mediates rhombomere-restricted expression and contains separate Pbx-Hox (PH) and Prep/Meis (P/M) binding sites. We further show that both the PH and P/M sites are essential for Hox-Pbx-Prep ternary complex formation and regulation of the Phox2b enhancer activity in ventral r4. Moreover, the DV factor Nkx2.2 enhances Hox-mediated transactivation via a derepression mechanism. Finally, we show that induction of ectopic Phox2b-expressing visceral motoneurons in the chick hindbrain requires the combined activities of Hox and Nkx2 homeodomain proteins. This study takes an important first step to understand how activators and repressors, induced along the AP and DV axes in response to signaling pathways, interact to regulate specific target gene promoters, leading to neuronal fate specification in the appropriate developmental context.

Molecular Interactions Involved in the Transactivation of the Human T-Cell Leukemia Virus Type 1 Promoter Mediated by Tax and CREB-2 (ATF-4)

PubMed Central

Gachon, Frederic; Thebault, Sabine; Peleraux, Annick; Devaux, Christian; Mesnard, Jean-Michel

2000-01-01

The human T-cell leukemia virus type 1 (HTLV-1) Tax protein activates viral transcription through three 21-bp repeats located in the U3 region of the HTLV-1 long terminal repeat and called Tax-responsive elements (TxREs). Each TxRE contains nucleotide sequences corresponding to imperfect cyclic AMP response elements (CRE). In this study, we demonstrate that the bZIP transcriptional factor CREB-2 is able to bind in vitro to the TxREs and that CREB-2 binding to each of the 21-bp motifs is enhanced by Tax. We also demonstrate that Tax can weakly interact with CREB-2 bound to a cellular palindromic CRE motif such as that found in the somatostatin promoter. Mutagenesis of Tax and CREB-2 demonstrates that both N- and C-terminal domains of Tax and the C-terminal region of CREB-2 are required for direct interaction between the two proteins. In addition, the Tax mutant M47, defective for HTLV-1 activation, is unable to form in vitro a ternary complex with CREB-2 and TxRE. In agreement with recent results suggesting that Tax can recruit the coactivator CREB-binding protein (CBP) on the HTLV-1 promoter, we provide evidence that Tax, CREB-2, and CBP are capable of cooperating to stimulate viral transcription. Taken together, our data highlight the major role played by CREB-2 in Tax-mediated transactivation. PMID:10779337

Evaluation of ternary blended cements for use in transportation concrete structures

NASA Astrophysics Data System (ADS)

Gilliland, Amanda Louise

This thesis investigates the use of ternary blended cement concrete mixtures for transportation structures. The study documents technical properties of three concrete mixtures used in federally funded transportation projects in Utah, Kansas, and Michigan that used ternary blended cement concrete mixtures. Data were also collected from laboratory trial batches of ternary blended cement concrete mixtures with mixture designs similar to those of the field projects. The study presents the technical, economic, and environmental advantages of ternary blended cement mixtures. Different barriers of implementation for using ternary blended cement concrete mixtures in transportation projects are addressed. It was concluded that there are no technical, economic, or environmental barriers that exist when using most ternary blended cement concrete mixtures. The technical performance of the ternary blended concrete mixtures that were studied was always better than ordinary portland cement concrete mixtures. The ternary blended cements showed increased durability against chloride ion penetration, alkali silica reaction, and reaction to sulfates. These blends also had less linear shrinkage than ordinary portland cement concrete and met all strength requirements. The increased durability would likely reduce life cycle costs associated with concrete pavement and concrete bridge decks. The initial cost of ternary mixtures can be higher or lower than ordinary portland cement, depending on the supplementary cementitious materials used. Ternary blended cement concrete mixtures produce less carbon dioxide emissions than ordinary portland cement mixtures. This reduces the carbon footprint of construction projects. The barriers associated with implementing ternary blended cement concrete for transportation projects are not significant. Supplying fly ash returns any investment costs for the ready mix plant, including silos and other associated equipment. State specifications can make designing ternary blended cements more acceptable by eliminating arbitrary limitations for supplementary cementitious materials (SCMs) use and changing to performance-based standards. Performance-based standards require trial batching of concrete mixture designs, which can be used to optimize ternary combinations of portland cement and SCMs. States should be aware of various SCMs that are appropriate for the project type and its environment.

Voltammetric study of the boric acid-salicylaldehyde-H-acid ternary system and its application to the voltammetric determination of boron.

PubMed

Kajiwara, Mari; Ito, Yoshio N; Miyazaki, Yoshinobu; Fujimori, Takao; Takehara, Kô; Yoshimura, Kazuhisa

2015-02-14

The ternary system of boric acid, salicylaldehyde (SA) and H-acid (HA) was voltammetrically studied from kinetic and equilibrium points of view. The effect of the SA substituents was also studied by using two analogs, 5-fluorosalicylaldehyde (F-SA) and 5-methylsalicylaldehyde (Me-SA). The three cathodic peaks of Azomethine H (AzH), Azomethine H-boric acid complex (AzB), and free SA were observed in the solution containing boric acid, SA and HA. The peak potentials of AzH and SA were shifted to negative potentials with increasing pH, while the peak potential of AzB was pH-independent. This difference indicates that a proton participates in the charge-transfer steps of the AzH and SA reductions, but not in that of the AzB reduction. The formation constants for the AzB complexation were similar among all the examined analogs. In the kinetic study, the reaction rate was higher in an acidic condition for the AzH formation, but in a neutral condition for the AzB formation. The rate constants for the AzB complexes were in the order of F-SA > SA ≈ Me-SA, indicating that the fluoro group accelerates the F-AzB complexation. The AzB complexation mechanism is considered to consist of more than three steps, i.e., the pre-equilibrium of the salicylaldehyde-boric acid complex (SA-B) formation, the nucleophilic attack of HA on SA-B, and the remaining some steps to form AzB. Based on these results, the voltammetric determination method of boron using F-SA was optimized, which allowed the boron concentration to be determined within only 5 min with a 0.03 mg B dm(-3) detection limit.

Traces of ternary relations

NASA Astrophysics Data System (ADS)

Zedam, Lemnaouar; Barkat, Omar; De Baets, Bernard

2018-05-01

In this paper, we generalize the notion of traces of a binary relation to the setting of ternary relations. With a given ternary relation, we associate three binary relations: its left, middle and right trace. As in the binary case, these traces facilitate the study and characterization of properties of a ternary relation. Interestingly, the traces themselves turn out to be the greatest solutions of relational inequalities associated with newly introduced compositions of a ternary relation with a binary relation (and vice versa).

Ternary Blend Composed of Two Organic Donors and One Acceptor for Active Layer of High-Performance Organic Solar Cells.

PubMed

Lee, Jong Won; Choi, Yoon Suk; Ahn, Hyungju; Jo, Won Ho

2016-05-04

Ternary blends composed of two donor absorbers with complementary absorptions provide an opportunity to enhance the short-circuit current and thus the power conversion efficiency (PCE) of organic solar cells. In addition to complementary absorption of two donors, ternary blends may exhibit favorable morphology for high-performance solar cells when one chooses properly the donor pair. For this purpose, we develop a ternary blend with two donors (diketopyrrolopyrrole-based polymer (PTDPP2T) and small molecule ((TDPP)2Ph)) and one acceptor (PC71BM). The solar cell made of a ternary blend with 10 wt % (TDPP)2Ph exhibits higher PCE of 7.49% as compared with the solar cells with binary blends, PTDPP2T:PC71BM (6.58%) and (TDPP)2Ph:PC71BM (3.21%). The higher PCE of the ternary blend solar cell is attributed mainly to complementary absorption of two donors. However, a further increase in (TDPP)2Ph content in the ternary blend (>10 wt %) decreases the PCE. The ternary blend with 10 wt % (TDPP)2Ph exhibits well-developed morphology with narrow-sized fibrils while the blend with 15 wt % (TDPP)2Ph shows phase separation with large-sized domains, demonstrating that the phase morphology and compatibility of ternary blend are important factors to achieve a high-performance solar cell made of ternary blends.

On-chip integrated optofluidic complex refractive index sensing using silicon photonic crystal nanobeam cavities.

PubMed

Zhang, Xingwang; Zhou, Guangya; Shi, Peng; Du, Han; Lin, Tong; Teng, Jinghua; Chau, Fook Siong

2016-03-15

Complex refractive index sensing is proposed and experimentally demonstrated in optofluidic sensors based on silicon photonic crystal nanobeam cavities. The sensitivities are 58 and 139 nm/RIU, respectively, for the real part (n) and the imaginary part (κ) of the complex refractive index, and the corresponding detection limits are 1.8×10(-5) RIU for n and 4.1×10(-6) RIU for κ. Moreover, the capability of the complex refractive index sensing method to detect the concentration composition of the ternary mixture is demonstrated without the surface immobilization of functional groups, which is impossible to realize with the conventional refractive index sensing scheme.

Unbound (bioavailable) IGF1 enhances somatic growth

PubMed Central

Elis, Sebastien; Wu, Yingjie; Courtland, Hayden-William; Cannata, Dara; Sun, Hui; Beth-On, Mordechay; Liu, Chengyu; Jasper, Hector; Domené, Horacio; Karabatas, Liliana; Guida, Clara; Basta-Pljakic, Jelena; Cardoso, Luis; Rosen, Clifford J.; Frystyk, Jan; Yakar, Shoshana

2011-01-01

SUMMARY Understanding insulin-like growth factor-1 (IGF1) biology is of particular importance because, apart from its role in mediating growth, it plays key roles in cellular transformation, organ regeneration, immune function, development of the musculoskeletal system and aging. IGF1 bioactivity is modulated by its binding to IGF-binding proteins (IGFBPs) and the acid labile subunit (ALS), which are present in serum and tissues. To determine whether IGF1 binding to IGFBPs is necessary to facilitate normal growth and development, we used a gene-targeting approach and generated two novel knock-in mouse models of mutated IGF1, in which the native Igf1 gene was replaced by Des-Igf1 (KID mice) or R3-Igf1 (KIR mice). The KID and KIR mutant proteins have reduced affinity for the IGFBPs, and therefore present as unbound IGF1, or ‘free IGF1’. We found that both KID and KIR mice have reduced serum IGF1 levels and a concomitant increase in serum growth hormone levels. Ternary complex formation of IGF1 with the IGFBPs and the ALS was markedly reduced in sera from KID and KIR mice compared with wild type. Both mutant mice showed increased body weight, body and bone lengths, and relative lean mass. We found selective organomegaly of the spleen, kidneys and uterus, enhanced mammary gland complexity, and increased skeletal acquisition. The KID and KIR models show unequivocally that IGF1-complex formation with the IGFBPs is fundamental for establishing normal body and organ size, and that uncontrolled IGF bioactivity could lead to pathological conditions. PMID:21628395

Bacillus subtilis δ Factor Functions as a Transcriptional Regulator by Facilitating the Open Complex Formation.

PubMed

Prajapati, Ranjit Kumar; Sengupta, Shreya; Rudra, Paulami; Mukhopadhyay, Jayanta

2016-01-15

Most bacterial RNA polymerases (RNAP) contain five conserved subunits, viz. 2α, β, β', and ω. However, in many Gram-positive bacteria, especially in fermicutes, RNAP is associated with an additional factor, called δ. For over three decades since its identification, it had been thought that δ functioned as a subunit of RNAP to enhance the level of transcripts by recycling RNAP. In support of the previous observations, we also find that δ is involved in recycling of RNAP by releasing the RNA from the ternary complex. We further show that δ binds to RNA and is able to recycle RNAP when the length of the nascent RNA reaches a critical length. However, in this work we decipher a new function of δ. Performing biochemical and mutational analysis, we show that Bacillus subtilis δ binds to DNA immediately upstream of the promoter element at A-rich sequences on the abrB and rrnB1 promoters and facilitates open complex formation. As a result, δ facilitates RNAP to initiate transcription in the second scale, compared with minute scale in the absence of δ. Using transcription assay, we show that δ-mediated recycling of RNAP cannot be the sole reason for the enhancement of transcript yield. Our observation that δ does not bind to RNAP holo enzyme but is required to bind to DNA upstream of the -35 promoter element for transcription activation suggests that δ functions as a transcriptional regulator. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Unbound (bioavailable) IGF1 enhances somatic growth.

PubMed

Elis, Sebastien; Wu, Yingjie; Courtland, Hayden-William; Cannata, Dara; Sun, Hui; Beth-On, Mordechay; Liu, Chengyu; Jasper, Hector; Domené, Horacio; Karabatas, Liliana; Guida, Clara; Basta-Pljakic, Jelena; Cardoso, Luis; Rosen, Clifford J; Frystyk, Jan; Yakar, Shoshana

2011-09-01

Understanding insulin-like growth factor-1 (IGF1) biology is of particular importance because, apart from its role in mediating growth, it plays key roles in cellular transformation, organ regeneration, immune function, development of the musculoskeletal system and aging. IGF1 bioactivity is modulated by its binding to IGF-binding proteins (IGFBPs) and the acid labile subunit (ALS), which are present in serum and tissues. To determine whether IGF1 binding to IGFBPs is necessary to facilitate normal growth and development, we used a gene-targeting approach and generated two novel knock-in mouse models of mutated IGF1, in which the native Igf1 gene was replaced by Des-Igf1 (KID mice) or R3-Igf1 (KIR mice). The KID and KIR mutant proteins have reduced affinity for the IGFBPs, and therefore present as unbound IGF1, or 'free IGF1'. We found that both KID and KIR mice have reduced serum IGF1 levels and a concomitant increase in serum growth hormone levels. Ternary complex formation of IGF1 with the IGFBPs and the ALS was markedly reduced in sera from KID and KIR mice compared with wild type. Both mutant mice showed increased body weight, body and bone lengths, and relative lean mass. We found selective organomegaly of the spleen, kidneys and uterus, enhanced mammary gland complexity, and increased skeletal acquisition. The KID and KIR models show unequivocally that IGF1-complex formation with the IGFBPs is fundamental for establishing normal body and organ size, and that uncontrolled IGF bioactivity could lead to pathological conditions.

Synergistic Growth of Giant Wormlike Micelles in Ternary Mixed Surfactant Solutions: Effect of Octanoic Acid.

PubMed

Georgieva, Gergana S; Anachkov, Svetoslav E; Lieberwirth, Ingo; Koynov, Kaloian; Kralchevsky, Peter A

2016-12-06

The synergistic growth of giant wormlike micelles in ternary mixed solutions composed of an anionic surfactant (sodium laurylethersulfate, SLES), a zwitterionic surfactant (cocamidopropyl betaine, CAPB), and octanoic acid (HC8) is studied. Rheological data and their analysis in terms of Cole-Cole plots and micellar characteristic times are presented, and the micellar structures behind the observed rheological behavior are revealed by cryo-TEM micrographs. The surfactant composition is fixed near the maximal micelle size of the binary SLES + CAPB system, whereas the concentration of HC8 is varied. At a given HC8 concentration, the viscosity of the ternary micellar solutions exhibits a very high and sharp peak. Polarized-light optical microscopy indicates that all investigated solutions are isotropic rather than liquid-crystalline. The cryo-TEM imaging shows complex phase behavior: wormlike micelles to the left of the peak, giant entangled wormlike micelles at the peak, and long wormlike micelles coexisting with multiconnected micellar aggregates to the right of the peak. The formation of multiconnected micelles leads to a drop in viscosity at the higher concentrations. The results contribute to a better understanding of the structure-rheology relations in micellar surfactant solutions and could be useful for controlling the properties of formulations in personal-care and house-hold detergency.

Characterization of Explosives Processing Waste Decomposition Due to Composting.

DTIC Science & Technology

1994-09-01

leachate were injected onto an Alltech RP-C 18/Anion column (150 mm x 4.6 mm ID) and were eluted at 1 mL/min using a complex ternary gradient of 0.015 M...the study because it is an agriculturally important legume; the seeds of this plant are also an important carbon sink. Thus, Glycine was advantageous

Biochemical and structural characterization of Cryptosporidium parvum Lactate dehydrogenase.

PubMed

Cook, William J; Senkovich, Olga; Hernandez, Agustin; Speed, Haley; Chattopadhyay, Debasish

2015-03-01

The protozoan parasite Cryptosporidium parvum causes waterborne diseases worldwide. There is no effective therapy for C. parvum infection. The parasite depends mainly on glycolysis for energy production. Lactate dehydrogenase is a major regulator of glycolysis. This paper describes the biochemical characterization of C. parvum lactate dehydrogenase and high resolution crystal structures of the apo-enzyme and four ternary complexes. The ternary complexes capture the enzyme bound to NAD/NADH or its 3-acetylpyridine analog in the cofactor binding pocket, while the substrate binding site is occupied by one of the following ligands: lactate, pyruvate or oxamate. The results reveal distinctive features of the parasitic enzyme. For example, C. parvum lactate dehydrogenase prefers the acetylpyridine analog of NADH as a cofactor. Moreover, it is slightly less sensitive to gossypol inhibition compared with mammalian lactate dehydrogenases and not inhibited by excess pyruvate. The active site loop and the antigenic loop in C. parvum lactate dehydrogenase are considerably different from those in the human counterpart. Structural features and enzymatic properties of C. parvum lactate dehydrogenase are similar to enzymes from related parasites. Structural comparison with malate dehydrogenase supports a common ancestry for the two genes. Copyright © 2014 Elsevier B.V. All rights reserved.

Net Expression Inhibits the Growth of Pancreatic Ductal Adenocarcinoma Cell PL45 In Vitro and In Vivo

PubMed Central

Li, Baiwen; Wan, Xinjian; Zhu, Qi; Li, Lei; Zeng, Yue; Hu, Duanmin; Qian, Yueqin; Lu, Lungen; Wang, Xingpeng; Meng, Xiangjun

2013-01-01

Pancreatic ductal adenocarcinoma has a poor prognosis due to late diagnosis and a lack of effective therapeutic options. Thus, it is important to better understand its molecular mechanisms and to develop more effective treatments for the disease. The ternary complex factor Net, which exerts its strong inhibitory function on transcription of proto-oncogene gene c-fos by forming ternary complexes with a second transcription factor, has been suspected of being involved in pancreatic cancer and other tumors biology. In this study, we found that the majority of pancreatic ductal adenocarcinoma tissues and cell lines had weak or no expression of Net, whereas significantly high level of Net expression occurred in paired adjacent normal tissues we studied. Furthermore, using in vitro and in vivo model systems, we found that overexpression of Net inhibited cell growth and survival and induced cell apoptosis in human pancreatic ductal adenocarcinoma cell PL45; the mechanisms by which Net inhibited the cell cycle progression were mainly through P21-Cyclin D1/CDK4 Pathway. Our data thus suggested that Net might play an important role in pancreatic carcinogenesis, possibly by acting as a tumor suppressor gene. PMID:23469073

NRAGE is involved in homologous recombination repair to resist the DNA-damaging chemotherapy and composes a ternary complex with RNF8-BARD1 to promote cell survival in squamous esophageal tumorigenesis.

PubMed

Yang, Q; Pan, Q; Li, C; Xu, Y; Wen, C; Sun, F

2016-08-01

NRAGE, a neurotrophin receptor-interacting melanoma antigen-encoding gene homolog, is significantly increased in the nucleus of radioresistant esophageal tumor cell lines and is highly upregulated to promote cell proliferation in esophageal carcinomas (ECs). However, whether the overexpressed NRAGE promotes cell growth by participating in DNA-damage response (DDR) is still unclear. Here we show that NRAGE is required for efficient double-strand breaks (DSBs) repair via homologous recombination repair (HRR) and downregulation of NRAGE greatly sensitizes EC cells to DNA-damaging agents both in vitro and in vivo. Moreover, NRAGE not only regulates the stability of DDR factors, RNF8 and BARD1, in a ubiquitin-proteolytic pathway, but also chaperons the interaction between BARD1 and RNF8 via their RING domains to form a novel ternary complex. Additionally, the expression of NRAGE is closely correlated with RNF8 and BARD1 in esophageal tumor tissues. In summary, our findings reveal a novel function of NRAGE that will help to guide personalized esophageal cancer treatments by targeting NRAGE to increase cell sensitivity to DNA-damaging therapeutics in the long run.

PRINCEPS: A computer-based approach to the structural description and recognition of trends within structural databases, and its application to the Ce-Ni-Si System

DOE PAGES

Guo, Yiming; Fredrickson, Daniel C.

2016-04-01

Intermetallic crystal structures offer an enormous structural diversity, with an endless array of structural motifs whose connection to stability and physical properties are often mysterious. Making sense of the often complex crystal structures that arise here, developing a clear structural description, and identifying connections to other phases can be laborious and require an encyclopedic knowledge of structure types. In this Article, we present PRINCEPS, an algorithm based on a new coordination environment projection scheme that facilitates the structural analysis and comparison of such crystal structures. We demonstrate the potential of this approach by applying it to the complex Ce-Ni-Si ternarymore » system, whose 17 binary and 21 ternary phases would present a daunting challenge to one seeking to understand the system by manual inspection (but has nonetheless been well-described through the heroic efforts of previous researchers). With the help of PRINCEPS, most of the ternary phases in this system can be rationalized as intergrowths of simple structural fragments, and grouped into a handful of structural series (with some outliers). Lastly, these results illustrate how the PRINCEPS approach can be used to organize a vast collection of crystal structures into structurally meaningful families, and guide the description of complex atomic arrangements.« less

Amorphous stabilization and dissolution enhancement of amorphous ternary solid dispersions: combination of polymers showing drug-polymer interaction for synergistic effects.

PubMed

Prasad, Dev; Chauhan, Harsh; Atef, Eman

2014-11-01

The purpose of this study was to understand the combined effect of two polymers showing drug-polymer interactions on amorphous stabilization and dissolution enhancement of indomethacin (IND) in amorphous ternary solid dispersions. The mechanism responsible for the enhanced stability and dissolution of IND in amorphous ternary systems was studied by exploring the miscibility and intermolecular interactions between IND and polymers through thermal and spectroscopic analysis. Eudragit E100 and PVP K90 at low concentrations (2.5%-40%, w/w) were used to prepare amorphous binary and ternary solid dispersions by solvent evaporation. Stability results showed that amorphous ternary solid dispersions have better stability compared with amorphous binary solid dispersions. The dissolution of IND from the ternary dispersion was substantially higher than the binary dispersions as well as amorphous drug. Melting point depression of physical mixtures reveals that the drug was miscible in both the polymers; however, greater miscibility was observed in ternary physical mixtures. The IR analysis confirmed intermolecular interactions between IND and individual polymers. These interactions were found to be intact in ternary systems. These results suggest that the combination of two polymers showing drug-polymer interaction offers synergistic enhancement in amorphous stability and dissolution in ternary solid dispersions. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Molecular dynamics study of polysaccharides in binary solvent mixtures of an ionic liquid and water.

PubMed

Liu, Hanbin; Sale, Kenneth L; Simmons, Blake A; Singh, Seema

2011-09-01

Some ionic liquids (ILs) have great promise as effective solvents for biomass pretreatment, and there are several that have been reported that can dissolve large amounts of cellulose. The solubilized cellulose can then be recovered by addition of antisolvents, such as water or ethanol, and this regeneration process plays an important role in the subsequent enzymatic saccharification reactions and in the recovery of the ionic liquid. To date, little is known about the fundamental intermolecular interactions that drive the dissolution and subsequent regeneration of cellulose in complex mixtures of ionic liquids, water, and cellulose. To investigate these interactions, in this work, molecular dynamics (MD) simulations were carried out to study binary and ternary mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) with water and a cellulose oligomer. Simulations of a cellulose oligomer dissolved in three concentrations of binary mixtures of [C2mim][OAc] and water were used to represent the ternary system in the dissolution phase (high [C2mim][OAc] concentration) and present during the initial phase of the regeneration step (intermediate and low [C2mim][OAc] concentrations). The MD analysis of the structure and dynamics that exist in these binary and ternary mixtures provides information on the key intermolecular interactions between cellulose and [C2mim][OAc] that lead to dissolution of cellulose and the key intermolecular interactions in the intermediate states of cellulose precipitation as a function of water content in the cellulose/IL/water system. The analysis of this intermediate state provides new insight into the molecular driving forces present in this ternary system. © 2011 American Chemical Society

A Solution-Doped Polymer Semiconductor:Insulator Blend for Thermoelectrics.

PubMed

Kiefer, David; Yu, Liyang; Fransson, Erik; Gómez, Andrés; Primetzhofer, Daniel; Amassian, Aram; Campoy-Quiles, Mariano; Müller, Christian

2017-01-01

Poly(ethylene oxide) is demonstrated to be a suitable matrix polymer for the solution-doped conjugated polymer poly(3-hexylthiophene). The polarity of the insulator combined with carefully chosen processing conditions permits the fabrication of tens of micrometer-thick films that feature a fine distribution of the F4TCNQ dopant:semiconductor complex. Changes in electrical conductivity from 0.1 to 0.3 S cm -1 and Seebeck coefficient from 100 to 60 μV K -1 upon addition of the insulator correlate with an increase in doping efficiency from 20% to 40% for heavily doped ternary blends. An invariant bulk thermal conductivity of about 0.3 W m -1 K -1 gives rise to a thermoelectric Figure of merit ZT ∼ 10 -4 that remains unaltered for an insulator content of more than 60 wt%. Free-standing, mechanically robust tapes illustrate the versatility of the developed dopant:semiconductor:insulator ternary blends.

Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project

NASA Astrophysics Data System (ADS)

Hummelshøj, J. S.; Landis, D. D.; Voss, J.; Jiang, T.; Tekin, A.; Bork, N.; Dułak, M.; Mortensen, J. J.; Adamska, L.; Andersin, J.; Baran, J. D.; Barmparis, G. D.; Bell, F.; Bezanilla, A. L.; Bjork, J.; Björketun, M. E.; Bleken, F.; Buchter, F.; Bürkle, M.; Burton, P. D.; Buus, B. B.; Calborean, A.; Calle-Vallejo, F.; Casolo, S.; Chandler, B. D.; Chi, D. H.; Czekaj, I.; Datta, S.; Datye, A.; DeLaRiva, A.; Despoja, V.; Dobrin, S.; Engelund, M.; Ferrighi, L.; Frondelius, P.; Fu, Q.; Fuentes, A.; Fürst, J.; García-Fuente, A.; Gavnholt, J.; Goeke, R.; Gudmundsdottir, S.; Hammond, K. D.; Hansen, H. A.; Hibbitts, D.; Hobi, E.; Howalt, J. G.; Hruby, S. L.; Huth, A.; Isaeva, L.; Jelic, J.; Jensen, I. J. T.; Kacprzak, K. A.; Kelkkanen, A.; Kelsey, D.; Kesanakurthi, D. S.; Kleis, J.; Klüpfel, P. J.; Konstantinov, I.; Korytar, R.; Koskinen, P.; Krishna, C.; Kunkes, E.; Larsen, A. H.; Lastra, J. M. G.; Lin, H.; Lopez-Acevedo, O.; Mantega, M.; Martínez, J. I.; Mesa, I. N.; Mowbray, D. J.; Mýrdal, J. S. G.; Natanzon, Y.; Nistor, A.; Olsen, T.; Park, H.; Pedroza, L. S.; Petzold, V.; Plaisance, C.; Rasmussen, J. A.; Ren, H.; Rizzi, M.; Ronco, A. S.; Rostgaard, C.; Saadi, S.; Salguero, L. A.; Santos, E. J. G.; Schoenhalz, A. L.; Shen, J.; Smedemand, M.; Stausholm-Møller, O. J.; Stibius, M.; Strange, M.; Su, H. B.; Temel, B.; Toftelund, A.; Tripkovic, V.; Vanin, M.; Viswanathan, V.; Vojvodic, A.; Wang, S.; Wellendorff, J.; Thygesen, K. S.; Rossmeisl, J.; Bligaard, T.; Jacobsen, K. W.; Nørskov, J. K.; Vegge, T.

2009-07-01

We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition metal atom (M2) plus two to five (BH4)- groups, i.e., M1M2(BH4)2-5, using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with promising decomposition energies. The M1(Al/Mn/Fe)(BH4)4, (Li/Na)Zn(BH4)3, and (Na/K)(Ni/Co)(BH4)3 alloys are found to be the most promising, followed by selected M1(Nb/Rh)(BH4)4 alloys.

Thermoelastic martensitic transformations in ternary Ni50Mn50- z Ga z alloys

NASA Astrophysics Data System (ADS)

Belosludtseva, E. S.; Kuranova, N. N.; Marchenkova, E. B.; Popov, A. G.; Pushin, V. G.

2016-01-01

We have studied the effect of gallium alloying on the structure, phase composition, and physical properties of ternary alloys of the Ni50Mn50- z Ga z (0 ≤ z ≤ 25 at %) quasi-binary section in a broad temperature range. Dependences of the type of crystalline structure of the high-temperature austenite phase and martensite, as well as the critical temperatures of martensitic transformations on the alloy composition, are determined. A phase diagram of the structural and magnetic transformations is constructed. Concentration boundaries of the existence of tetragonal L10 (2 M) martensite and martensitic phases (10 M and 14 M) with complex multilayer crystalline lattices are found. It is established that the predominant martensite morphology is determined by the hierarchy of packets of thin coherent nano- and submicrocrystalline plates with habit planes close to {011} B2, pairwise twinned along one of 24 equivalent {011}<011> B2 twinning shear systems.

A comparison of acoustic levitation with microgravity processing for containerless solidification of ternary Al-Cu-Sn alloy

NASA Astrophysics Data System (ADS)

Yan, N.; Hong, Z. Y.; Geng, D. L.; Wei, B.

2015-07-01

The containerless rapid solidification of liquid ternary Al-5 %Cu-65 %Sn immiscible alloy was accomplished at both ultrasonic levitation and free fall conditions. A maximum undercooling of 185 K (0.22 T L) was obtained for the ultrasonically levitated alloy melt at a cooling rate of about 122 K s-1. Meanwhile, the cooling rate of alloy droplets in drop tube varied from 102 to 104 K s-1. The macrosegregation was effectively suppressed through the complex melt flow under ultrasonic levitation condition. In contrast, macrosegregation became conspicuous and core-shell structures with different layers were formed during free fall. The microstructure formation mechanisms during rapid solidification at containerless states were investigated in comparison with the conventional static solidification process. It was found that the liquid phase separation and structural growth kinetics may be modulated by controlling both alloy undercooling and cooling rate.

A Solution‐Doped Polymer Semiconductor:Insulator Blend for Thermoelectrics

PubMed Central

Kiefer, David; Yu, Liyang; Fransson, Erik; Gómez, Andrés; Primetzhofer, Daniel; Amassian, Aram; Campoy‐Quiles, Mariano

2016-01-01

Poly(ethylene oxide) is demonstrated to be a suitable matrix polymer for the solution‐doped conjugated polymer poly(3‐hexylthiophene). The polarity of the insulator combined with carefully chosen processing conditions permits the fabrication of tens of micrometer‐thick films that feature a fine distribution of the F4TCNQ dopant:semiconductor complex. Changes in electrical conductivity from 0.1 to 0.3 S cm−1 and Seebeck coefficient from 100 to 60 μV K−1 upon addition of the insulator correlate with an increase in doping efficiency from 20% to 40% for heavily doped ternary blends. An invariant bulk thermal conductivity of about 0.3 W m−1 K−1 gives rise to a thermoelectric Figure of merit ZT ∼ 10−4 that remains unaltered for an insulator content of more than 60 wt%. Free‐standing, mechanically robust tapes illustrate the versatility of the developed dopant:semiconductor:insulator ternary blends. PMID:28105396

The role of wine polysaccharides on salivary protein-tannin interaction: A molecular approach.

PubMed

Brandão, Elsa; Silva, Mafalda Santos; García-Estévez, Ignacio; Williams, Pascale; Mateus, Nuno; Doco, Thierry; de Freitas, Victor; Soares, Susana

2017-12-01

Polysaccharides are described to inhibit aggregation between food polyphenols and salivary proteins (SP) and may hence lead to astringency modulation. In this work, the effect of two wine polysaccharides (arabinogalactan proteins-AGPs and rhamnogalacturonan II- RGII) on SP-polyphenol interaction was evaluated. In general, both polysaccharides were effective to inhibit or reduce SP-polyphenol interaction and aggregation. They can act by two different mechanisms (ternary or competitive) depending on the SP-tannin pair. In the case of salivary P-B peptide, AGPs and RGII seem to act by a ternary mechanism, in which they surround this complex, enhancing its solubility. Concerning acidic proline-rich proteins (aPRPs), it was possible to observe both mechanisms, depending on the tannin and the polysaccharide involved. Overall, this work point out for a specific property of wine polysaccharides important to modulate this and other beverages and food astringency perception. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formation of Cucurbit[8]uril-Based Supramolecular Hydrogel Beads Using Droplet-Based Microfluidics.

PubMed

Xu, Xuejiao; Appel, Eric A; Liu, Xin; Parker, Richard M; Scherman, Oren A; Abell, Chris

2015-09-14

Herein we describe the use of microdroplets as templates for the fabrication of uniform-sized supramolecular hydrogel beads, assembled by supramolecular cross-linking of functional biopolymers with the macrocyclic host molecule, cucurbit[8]uril (CB[8]). The microdroplets were formed containing diluted hydrogel precursors in solution, including the functional polymers and CB[8], in a microfluidic device. Subsequent evaporation of water from collected microdroplets concentrated the contents, driving the formation of the CB[8]-mediated host-guest ternary complex interactions and leading to the assembly of condensed three-dimensional polymeric scaffolds. Rehydration of the dried particles gave monodisperse hydrogel beads. Their equilibrium size was shown to be dependent on both the quantity of material loaded and the dimensions of the microfluidic flow focus. Fluorescein-labeled dextran was used to evaluate the efficacy of the hydrogel beads as a vector for controlled cargo release. Both passive, sustained release (hours) and triggered, fast release (minutes) of the FITC-dextran was observed, with the rate of sustained release dependent on the formulation. The kinetics of release was fitted to the Ritger-Peppas controlled release equation and shown to follow an anomalous (non-Fickian) transport mechanism.

A gate-latch-lock mechanism for hormone signalling by abscisic acid receptors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melcher, Karsten; Ng, Ley-Moy; Zhou, X Edward

2010-01-12

Abscisic acid (ABA) is a ubiquitous hormone that regulates plant growth, development and responses to environmental stresses. Its action is mediated by the PYR/PYL/RCAR family of START proteins, but it remains unclear how these receptors bind ABA and, in turn, how hormone binding leads to inhibition of the downstream type 2C protein phosphatase (PP2C) effectors. Here we report crystal structures of apo and ABA-bound receptors as well as a ternary PYL2-ABA-PP2C complex. The apo receptors contain an open ligand-binding pocket flanked by a gate that closes in response to ABA by way of conformational changes in two highly conserved β-loopsmore » that serve as a gate and latch. Moreover, ABA-induced closure of the gate creates a surface that enables the receptor to dock into and competitively inhibit the PP2C active site. A conserved tryptophan in the PP2C inserts directly between the gate and latch, which functions to further lock the receptor in a closed conformation. Together, our results identify a conserved gate-latch-lock mechanism underlying ABA signalling.« less

Crystal structure of a polyhistidine-tagged recombinant catalytic subunit of cAMP-dependent protein kinase complexed with the peptide inhibitor PKI(5-24) and adenosine.

PubMed

Narayana, N; Cox, S; Shaltiel, S; Taylor, S S; Xuong, N

1997-04-15

The crystal structure of the hexahistidine-tagged mouse recombinant catalytic subunit (H6-rC) of cAMP-dependent protein kinase (cAPK), complexed with a 20-residue peptide inhibitor from the heat-stable protein kinase inhibitor PKI(5-24) and adenosine, was determined at 2.2 A resolution. Novel crystallization conditions were required to grow the ternary complex crystals. The structure was refined to a final crystallographic R-factor of 18.2% with good stereochemical parameters. The "active" enzyme adopts a "closed" conformation as found in rC:PKI(5-24) [Knighton et al. (1991a,b) Science 253, 407-414, 414-420] and packs in a similar manner with the peptide providing a major contact surface. This structure clearly defines the subsites of the unique nucleotide binding site found in the protein kinase family. The adenosine occupies a mostly hydrophobic pocket at the base of the cleft between the two lobes and is completely buried. The missing triphosphate moiety of ATP is filled with a water molecule (Wtr 415) which replaces the gamma-phosphate of ATP. The glycine-rich loop between beta1 and beta2 helps to anchor the phosphates while the ribose ring is buried beneath beta-strand 2. Another ordered water molecule (Wtr 375) is pentacoordinated with polar atoms from adenosine, Leu 49 in beta-strand 1, Glu 127 in the linker strand between the two lobes, Tyr 330, and a third water molecule, Wtr 359. The conserved nucleotide fold can be defined as a lid comprised of beta-strand 1, the glycine-rich loop, and beta-strand 2. The adenine ring is buried beneath beta-strand 1 and the linker strand (120-127) that joins the small and large lobes. The C-terminal tail containing Tyr 330, a segment that lies outside the conserved core, covers this fold and anchors it in a closed conformation. The main-chain atoms of the flexible glycine-rich loop (residues 50-55) in the ATP binding domain have a mean B-factor of 41.4 A2. This loop is quite mobile, in striking contrast to the other conserved loops that converge at the active site cleft. The catalytic loop (residues 166-171) and the Mg2+ positioning loop (residues 184-186) are a stable part of the large lobe and have low B-factors in all structures solved to date. The stability of the glycine-rich loop is highly dependent on the ligands that occupy the active site cleft with maximum stability achieved in the ternary complex containing Mg x ATP and the peptide inhibitor. In this ternary complex the gamma-phosphate is secured between both lobes by hydrogen bonds to the backbone amide of Ser 53 in the glycine-rich loop and the amino group of Lys 168 in the catalytic loop. In the adenosine ternary complex the water molecule replacing the gamma-phosphate hydrogen bonds between Lys 168 and Asp 166 and makes no contact with the small lobe. This glycine-rich loop is thus the most mobile component of the active site cleft, with the tip of the loop being highly sensitive to what occupies the gamma-subsite.

Speciation study in the sulfamethoxazole-copper-pH-soil system: implications for retention prediction.

PubMed

Morel, Marie-Christine; Spadini, Lorenzo; Brimo, Khaled; Martins, Jean M F

2014-05-15

Sulfamethoxazole (SMX) is a persistent sulfonamide antibiotic drug used in the veterinary and human medical sectors and is widely detected in natural waters. To better understand the reactive transport of this antibiotic in soil, the speciation of the SMX-Cu(II)-H(+) system in solution and the combined sorption of these components in a natural vineyard soil were investigated by acid-base titrimetry and infrared spectroscopy. Cu(II) is considered to represent a strongly complexing trace element cation (such as Cd(2+), Zn(2+), Pb(2+), Ni(2+), etc.) in comparison to more prevalent but more weakly binding cations (such as Ca(2+) and Mg(2+)). Titrimetric studies showed that, relative to other antibiotics, such as tetracycline, SMX is a weak copper chelating agent and a weak soil sorbent at the soil pH (pH6). However, the sorption of SMX in soil increases strongly (by a factor of 6) in the presence of copper. This finding strongly supports the hypothetical formation of ternary SMX-Cu-soil complexes, especially considering that copper is dominantly sorbed in a state at pH6. The data were successfully modelled with PhreeqC assuming the existence of binary and ternary surface complexes in equilibrium with aqueous Cu, SMX and Cu-SMX complexes. It is thought that other strongly complexing cations present on the surface of reactive organic and mineral soil phases, such as Cd(II), Ni(II), Zn(II), Pb(II), Fe(II/III), Mn(II/IV) and Al(III), affect the solid/solution partitioning of SMX. This study thus suggests that surface-adsorbed cations significantly increase the sorption of SMX. Copyright © 2014 Elsevier B.V. All rights reserved.

Dissecting the Catalytic Mechanism of Betaine-Homocysteine S-Methyltransferase Using Intrinsic Tryptophan Fluorescence and Site-Directed Mutagenesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castro, C.; Gratson, A.A.; Evans, J.C.

2010-03-05

Betaine-homocysteine S-methyltransferase (BHMT) is a zinc-dependent enzyme that catalyzes the transfer of a methyl group from glycine betaine (Bet) to homocysteine (Hcy) to form dimethylglycine (DMG) and methionine (Met). Previous studies in other laboratories have indicated that catalysis proceeds through the formation of a ternary complex, with a transition state mimicked by the inhibitor S-({delta}-carboxybutyl)-l-homocysteine (CBHcy). Using changes in intrinsic tryptophan fluorescence to determine the affinity of human BHMT for substrates, products, or CBHcy, we now demonstrate that the enzyme-substrate complex reaches its transition state through an ordered bi-bi mechanism in which Hcy is the first substrate to bind andmore » Met is the last product released. Hcy, Met, and CBHcy bind to the enzyme to form binary complexes with K{sub d} values of 7.9, 6.9, and 0.28 {micro}M, respectively. Binary complexes with Bet and DMG cannot be detected with fluorescence as a probe, but Bet and DMG bind tightly to BHMT-Hcy to form ternary complexes with K{sub d} values of 1.1 and 0.73 {micro}M, respectively. Mutation of each of the seven tryptophan residues in human BHMT provides evidence that the enzyme undergoes two distinct conformational changes that are reflected in the fluorescence of the enzyme. The first is induced when Hcy binds, and the second, when Bet binds. As predicted by the crystal structure of BHMT, the amino acids Trp44 and Tyr160 are involved in binding Bet, and Glu159 in binding Hcy. Replacing these residues by site-directed mutagenesis significantly reduces the catalytic efficiency (V{sub max}/K{sub m}) of the enzyme. Replacing Tyr77 with Phe abolishes enzyme activity.« less

Copper(II) complexes with uridine, uridine 5'-monophosphate, spermidine, or spermine in aqueous solution.

PubMed

Lomozik, Lechoslaw; Jastrzab, Renata

2003-01-15

Molecular complexes of the types (Urd)H(x)(PA) and (UMP)H(x)(PA) are formed in the uridine (Urd) or uridine 5'-monophosphate (UMP) plus spermidine or spermine systems, as shown by the results of equilibrium and spectral studies. Overall stability constants of the adducts and equilibrium constants of their formation have been determined. An increase in the efficiency of the reaction between the bioligands is observed with increasing length of the polyamine. The pH range of adduct formation is found to coincide with that in which the polyamine is protonated while uridine or its monophosphate is deprotonated. The -NH(x)(+) groups from PA and the N(3) atom of the purine base as well as phosphate groups from the nucleotides have been identified as the significant centres of non-covalent interactions. Compared to cytidine, the pH range of Urd adduct formation is shifted significantly higher due to differences in the protonation constants of the endocyclic N(3) donor atoms of particular nucleosides. Overall stability constants of the Cu(II) complexes with uridine and uridine 5'-monophosphate in ternary systems with spermidine or spermine have been determined. It has been found from spectral data that in the Cu(II) ternary complexes with nucleosides and polyamines the reaction of metallation involves mainly N(3) atoms from the pyrimidine bases, as well as the amine groups of PA. This unexpected type of interaction has been evidenced in the coordination mode of the complexes forming in the Cu-UMP systems including spermidine or spermine. Results of spectral and equilibrium studies indicate that the phosphate groups taking part in metallation are at the same time involved in non-covalent interaction with the protonated polyamine.

CUB domain-containing protein 1 and the epidermal growth factor receptor cooperate to induce cell detachment.

PubMed

Law, Mary E; Ferreira, Renan B; Davis, Bradley J; Higgins, Paul J; Kim, Jae-Sung; Castellano, Ronald K; Chen, Sixue; Luesch, Hendrik; Law, Brian K

2016-08-05

While localized malignancies often respond to available therapies, most disseminated cancers are refractory. Novel approaches, therefore, are needed for the treatment of metastatic disease. CUB domain-containing protein1 (CDCP1) plays an important role in metastasis and drug resistance; the mechanism however, is poorly understood. Breast cancer cell lines were engineered to stably express EGFR, CDCP1 or phosphorylation site mutants of CDCP1. These cell lines were used for immunoblot analysis or affinity purification followed by immunoblot analysis to assess protein phosphorylation and/or protein complex formation with CDCP1. Kinase activity was evaluated using phosphorylation site-specific antibodies and immunoblot analysis in in vitro kinase assays. Protein band excision and mass spectrometry was utilized to further identify proteins complexed with CDCP1 or ΔCDCP1, which is a mimetic of the cleaved form of CDCP1. Cell detachment was assessed using cell counting. This paper reports that CDCP1 forms ternary protein complexes with Src and EGFR, facilitating Src activation and Src-dependent EGFR transactivation. Importantly, we have discovered that a class of compounds termed Disulfide bond Disrupting Agents (DDAs) blocks CDCP1/EGFR/Src ternary complex formation and downstream signaling. CDCP1 and EGFR cooperate to induce detachment of breast cancer cells from the substratum and to disrupt adherens junctions. Analysis of CDCP1-containing complexes using proteomics techniques reveals that CDCP1 associates with several proteins involved in cell adhesion, including adherens junction and desmosomal cadherins, and cytoskeletal elements. Together, these results suggest that CDCP1 may facilitate loss of adhesion by promoting activation of EGFR and Src at sites of cell-cell and cell-substratum contact.

An approach to control tuning range and speed in 1D ternary photonic band gap material nano-layered optical filter structures electro-optically

NASA Astrophysics Data System (ADS)

Zia, Shahneel; Banerjee, Anirudh

2016-05-01

This paper demonstrates a way to control spectrum tuning capability in one-dimensional (1D) ternary photonic band gap (PBG) material nano-layered structures electro-optically. It is shown that not only tuning range, but also tuning speed of tunable optical filters based on 1D ternary PBG structures can be controlled Electro-optically. This approach finds application in tuning range enhancement of 1D Ternary PBG structures and compensating temperature sensitive transmission spectrum shift in 1D Ternary PBG structures.

An approach to control tuning range and speed in 1D ternary photonic band gap material nano-layered optical filter structures electro-optically

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zia, Shahneel, E-mail: shahneelzia@gmail.com; Banerjee, Anirudh, E-mail: abanerjee@amity.edu

2016-05-06

This paper demonstrates a way to control spectrum tuning capability in one-dimensional (1D) ternary photonic band gap (PBG) material nano-layered structures electro-optically. It is shown that not only tuning range, but also tuning speed of tunable optical filters based on 1D ternary PBG structures can be controlled Electro-optically. This approach finds application in tuning range enhancement of 1D Ternary PBG structures and compensating temperature sensitive transmission spectrum shift in 1D Ternary PBG structures.

Sorption of Eu(III) on humic acid or fulvic acid bound to hydrous alumina studied by SEM-EDS, XPS, TRLFS, and batch techniques.

PubMed

Tan, X L; Wang, X K; Geckeis, H; Rabung, Th

2008-09-01

To identify the effect of humic acid (HA) and fulvic acid (FA) on the sorption mechanism of Eu(III) on organic--inorganic colloids in the environment at a molecular level, surface adsorbed/ complexed Eu(III) on hydrous alumina, HA-, and FA-hydrous alumina hybrids were characterized by using X-ray photoelectron spectroscopy (XPS) and time-resolved laser fluorescence spectroscopy (TRLFS). The experiments were performed in 0.1 mol/L KNO3 or 0.1 mol/L NaClO4 under ambient conditions. The pH values were varied between 2 and 11 at a fixed Eu(III) concentration of 6.0 x 10(-7) mol/L and 4.3 x 10(-5) mol/L. The different Eu(III)/FA(HA)/hydrous alumina complexes were characterized by their fluorescence emission spectra ((5D0-F1)/ (5D0 --> 7F2)) and binding energy of Eu(III). Inner-sphere surface complexation may contribute mainly to Eu(III) sorption on hydrous alumina, and a ternary surface complex is formed at the HA/ FA-hydrous alumina hybrid surfaces. The sorption and species of Eu(III) in ternary Eu-HA/FA-hydrous alumina systems are not dominated by either HA/FA or hydrous alumina, but are dominated by both HA/FA and hydrous alumina. The results are important for understanding the sorption mechanisms and the nature of surface adsorbed Eu(III) species and trivalent chemical homologues of Eu(III) in the natural environment.

Evidence of an inverted hexagonal phase in self-assembled phospholipid-DNA-metal complexes

NASA Astrophysics Data System (ADS)

Francescangeli, O.; Pisani, M.; Stanic, V.; Bruni, P.; Weiss, T. M.

2004-08-01

We report the first observation of an inverted hexagonal phase of phospholipid-DNA-metal complexes. These ternary complexes are formed in a self-assembled manner when water solutions of neutral lipid dioleoylphosphatidylethanolamine (DOPE), DNA and divalent metal cations (Me2+; Me=Fe, Co, Mg, Mn) are mixed, which represents a striking example of supramolecular chemistry. The structure, derived from synchrotron X-ray diffraction, consists of cylindrical DNA strands coated by neutral lipid monolayers and arranged on a two-dimensional hexagonal lattice (HIIc). Besides the fundamental aspects, DOPE-DNA-Me2+ complexes may be of great interest as efficient nonviral delivery systems in gene therapy applications because of the low inherent cytotoxicity and the potential high transfection efficiency.

Structural Investigations of the Nickel-Induced Inhibition of Truncated Constructs of the JMJD2 Family of Histone Demethylases Using X-ray Absorption Spectroscopy

PubMed Central

Giri, Nitai Charan; Passantino, Lisa; Sun, Hong; Zoroddu, Maria Antonietta; Costa, Max; Maroney, Michael J.

2013-01-01

Occupational and/or environmental exposure to nickel has been implicated in various types of cancer, and in vitro exposure to nickel compounds results in accumulation of Ni(II) ions in cells. One of the major targets of Ni(II) ions inside the cell is Fe(II)- and αKG-dependent dioxygenases. Using JMJD2A and JMJD2C as examples, we show that JMJD2 family of histone demethylases, which are products of putative oncogenes as well as Fe(II)- and αKG-dependent dioxygenases, are highly sensitive to inhibition by Ni(II) ions. In this work, X-ray absorption spectroscopy (XAS) has been used to investigate the Fe(II) active site of truncated JMJD2A and JMJD2C (1 – 350 aa) in the presence and absence of αKG and/or substrate to obtain mechanistic details of the early steps in catalysis that precede O2 binding in histone demethylation by the JMJD2 family of histone demethylases. Zinc K-edge XAS has been performed on the resting JMJD2A (with iron in the active site) to confirm the presence of the expected structural zinc site. XAS of the Ni(II)-substituted enzymes has also been performed to investigate the inhibition of these enzymes by Ni(II) ions. Our XAS results indicate that the five-coordinate Fe(II) center in the resting enzyme is retained in the binary and ternary complexes. In contrast, the Ni(II) center is six-coordinate in the resting enzyme, binary and ternary complexes. XAS results indicate that both Fe(II) and Ni(II) bind αKG in the binary and ternary complexes. The electron density build-up that is observed at the Fe(II) center in the presence of αKG and substrate is not observed at the Ni(II) center. Thus, both electronic and steric factors are responsible for Ni-induced inhibition of the JMJD2 family of histone demethylases. Ni-induced inhibition of these enzymes may explain the alteration of the epigenetic mechanism of gene expression that is responsible for Ni-induced carcinogenesis. PMID:23692052

Effect of Phosphate on U(VI) Sorption to Montmorillonite: Ternary Complexation and Precipitation Barriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Troyer, Lyndsay D.; Maillot, Fabien; Wang, Zheming

Phosphate addition is a potential treatment method to lower the solubility of U(VI) in soil and groundwater systems by causing U(VI) phosphate precipitation as well as enhancing adsorption. Previous work has shown that iron oxide surfaces may facilitate the nucleation of U(VI) phosphate minerals and, that under weakly acidic conditions, phosphate also enhances U(VI) adsorption to such phases. Like iron oxides, clays are important reactive phases in the subsurface but little is known about the interaction of U(VI) and phosphate with these minerals. The effect of aqueous phosphate on U(VI) binding to Wyoming montmorillonite (SWy-2) in air-equilibrated systems was investigated.more » Equilibrium U(VI) uptake to montmorillonite was determined at pH 4, 6 and 8 at discrete initial phosphate concentrations between 0 and 100 μM. The observed behavior of U(VI) indicates a transition from adsorption to precipitation with increasing total uranium and phosphate concentrations at all pH values. At the highest phosphate concentration examined at each pH value, a barrier to U(VI) phosphate nucleation is observed. At lower concentrations, phosphate has no effect on macroscopic U(VI) adsorption. To assess the mechanisms of U(VI)-phosphate interactions on smectite surfaces, U(VI) speciation was investigated under selected conditions using laser-induced fluorescence spectroscopy (LIFS) and extended X-ray absorption fine-structure (EXAFS) spectroscopy. Samples above the precipitation threshold display EXAFS and LIFS spectral signatures consistent with the autunite family of U(VI) phosphate minerals. However, at lower U(VI) concentrations, changes in LIFS spectra upon phosphate addition suggest that U(VI)-phosphate ternary surface complexes form on the montmorillonite surface at pH 4 and 6 despite the lack of a macroscopic effect on adsorption. The speciation of solid-associated U(VI) below the precipitation threshold at pH 8 is dominated by U(VI)-carbonate surface complexes. This work reveals that ternary complexation may occur without a macroscopic signature, which is attributed to phosphate not appreciably binding to smectite in the absence of U(VI), with U(VI) surface complexes serving as the sole reactive surface sites for phosphate. This study shows that phosphate does not enhance U(VI) adsorption to smectite clay minerals, unlike oxide phases, and that a barrier to homogeneous nucleation of U(VI) phosphates was not affected by the presence of the smectite surface« less

Structural variety in copper(II) complexes of 3-formylchromone: Synthesis, spectral, thermal, molecular modeling and biological studies

NASA Astrophysics Data System (ADS)

Shebl, Magdy; Adly, Omima M. I.; Taha, A.; Elabd, N. N.

2017-11-01

The compound in the title (L) was synthesized and reacted with Cu(II) metal ion with different anions (OAc-, NO3-, SO42-, ClO4-, Cl- and Br-) in absence and presence of auxiliary ligands (L‧); N,O-donor; or N,N-donor; to form binary and ternary Cu(II)-chelates. The metal complexes were fully characterized by analytical and spectral techniques in addition to thermal, conductivity and magnetic susceptibility measurements. The obtained results showed that the ligand behaves as a neutral bidentate, forming chelates with molar ratios: 1:1, 1:2 and 1:3; M:L for binary and 1:2:1 and 1:1:1; M:L:L‧ for ternary complexes, which can be formulated as: [LmCuXn(H2O)y]·zH2O, m = 1 or 2, n = 0, 1 or 2, X = OAc-, SO42-, Cl- or Br-, y = 0 or 2, z = 0 or 0.5; [LmCu(H2O)n]X2·zMeOH, m = 2 or 3, n = 0 or 2, X = ClO4- or NO3-, z = 0 or 1 and [Lm L'Cu(H2O)n](NO3)x·yS, m = 1 or 2, n = 0 or 2, X = 1 or 2, y = 0.5 or 4, S = H2O or MeOH. The ESR spin Hamiltonian parameters of some complexes were calculated. Kinetic parameters (Ea, A, ΔH, ΔS and ΔG) of the thermal decomposition stages have been evaluated using Coats-Redfern equations. The structural parameters of the ligand and its metal complexes have been calculated and correlated with the experimental data. The metal complexes exhibited octahedral and square planar geometrical arrangements according to the nature of the anion. The ligand and its metal complexes showed antibacterial activity towards Gram-positive bacteria, Gram-negative bacteria, yeast and fungus.

Requirements for selective recruitment of Ets proteins and activation of mb-1/Ig-α gene transcription by Pax-5 (BSAP)

PubMed Central

Maier, Holly; Ostraat, Rachel; Parenti, Sarah; Fitzsimmons, Daniel; Abraham, Lawrence J.; Garvie, Colin W.; Hagman, James

2003-01-01

Pax-5, a member of the paired domain family of transcription factors, is a key regulator of B lymphocyte-specific transcription and differentiation. A major target of Pax-5-mediated activation is the mb-1 gene, which encodes the essential transmembrane signaling protein Ig-α. Pax-5 recruits three members of the Ets family of transcription factors: Ets-1, Fli-1 and GABPα (with GABPβ1), to assemble ternary complexes on the mb-1 promoter in vitro. Using the Pax-5:Ets-1:DNA crystal structure as a guide, we defined amino acid requirements for transcriptional activation of endogenous mb-1 genes using a novel cell-based assay. Mutations in the β-hairpin/β-turn of the DNA-binding domain of Pax-5 demonstrated its importance for DNA sequence recognition and activation of mb-1 transcription. Mutations of amino acids contacting Ets-1 in the crystal structure reduced or blocked mb-1 promoter activation. One of these mutations, Q22A, resulted in greatly reduced mb-1 gene transcript levels, concurrent with the loss of its ability to recruit Fli-1 to bind the promoter in vitro. In contrast, the mutation had no effect on recruitment of the related Ets protein GABPα (with GABPβ1). These data further define requirements for Pax-5 function in vivo and reveal the complexity of interactions required for cooperative partnerships between transcription factors. PMID:14500810

Acetylation of androgen receptor by ARD1 promotes dissociation from HSP90 complex and prostate tumorigenesis

PubMed Central

Zhang, Guanyi; Qian, Chiping; Zhang, Haitao; Zabaleta, Jovanny; Liu, Wanguo

2016-01-01

Prostate cancer is an androgen receptor (AR)-driven disease and post-translational modification of AR is critical for AR activation. We previously reported that Arrest-defective protein 1 (ARD1) is an oncoprotein in prostate cancer. It acetylates and activates AR to promote prostate tumorigenesis. However, the ARD1-targeted residue within AR and the mechanisms of the acetylation event in prostate tumorigenesis remained unknown. In this study, we show that ARD1 acetylates AR at lysine 618 (K618) in vitro and in vivo. An AR construct with the charged lysine substitution by arginine (AR-618R) reduces RNA Pol II binding, AR transcriptional activity, prostate cancer cell growth, and xenograft tumor formation due to attenuation of AR nuclear translocation, whereas, construct mimicking neutral polar substitution acetylation at K618 by glutamine (AR-618Q) enhanced these effects beyond that of the wild-type AR. Mechanistically, ARD1 forms a ternary complex with AR and HSP90 in vitro and in vivo. Expression of ARD1 increases levels of AR acetylation and AR-HSP90 dissociation in a dose dependent manner. Moreover, the AR acetylation defective K618R mutant is unable to dissociate from HSP90 while the HSP90-dissociated AR is acetylated following ligand exposure. This work identifies a new mechanism for ligand-induced AR-HSP90 dissociation and AR activation. Targeting ARD1-mediated AR acetylation may be a potent intervention for AR-dependent prostate cancer therapy. PMID:27659526

Regulation of TCF ETS-domain transcription factors by helix-loop-helix motifs.

PubMed

Stinson, Julie; Inoue, Toshiaki; Yates, Paula; Clancy, Anne; Norton, John D; Sharrocks, Andrew D

2003-08-15

DNA binding by the ternary complex factor (TCF) subfamily of ETS-domain transcription factors is tightly regulated by intramolecular and intermolecular interactions. The helix-loop-helix (HLH)-containing Id proteins are trans-acting negative regulators of DNA binding by the TCFs. In the TCF, SAP-2/Net/ERP, intramolecular inhibition of DNA binding is promoted by the cis-acting NID region that also contains an HLH-like motif. The NID also acts as a transcriptional repression domain. Here, we have studied the role of HLH motifs in regulating DNA binding and transcription by the TCF protein SAP-1 and how Cdk-mediated phosphorylation affects the inhibitory activity of the Id proteins towards the TCFs. We demonstrate that the NID region of SAP-1 is an autoinhibitory motif that acts to inhibit DNA binding and also functions as a transcription repression domain. This region can be functionally replaced by fusion of Id proteins to SAP-1, whereby the Id moiety then acts to repress DNA binding in cis. Phosphorylation of the Ids by cyclin-Cdk complexes results in reduction in protein-protein interactions between the Ids and TCFs and relief of their DNA-binding inhibitory activity. In revealing distinct mechanisms through which HLH motifs modulate the activity of TCFs, our results therefore provide further insight into the role of HLH motifs in regulating TCF function and how the inhibitory properties of the trans-acting Id HLH proteins are themselves regulated by phosphorylation.

In situ fabrication of the Bi2O3-V2O5 hybrid embedded with graphitic carbon nitride nanosheets: Oxygen vacancies mediated enhanced visible-light-driven photocatalytic degradation of organic pollutants and hydrogen evolution

NASA Astrophysics Data System (ADS)

Vattikuti, S. V. Prabhakar; Police, Anil Kumar Reddy; Shim, Jaesool; Byon, Chan

2018-07-01

Novel mesoporous ternary hybrids comprising Bi2O3/V2O5 photocatalysts anchored on graphitic carbon nitride (g-C3N4) nanosheets were synthesized via an in situ co-pyrolysis approach and characterized by a series of techniques, including X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, thermogravimetric-differential thermal analysis, Fourier transform infrared spectroscopy, ultraviolet-visible spectrometry, photoluminescence and electron paramagnetic resonance (EPR). The hybrids were subsequently tested as photocatalysts for the degradation of the phenol red (PR) pollutant under visible light irradiation. The well-designed ternary hybrids showed pure and randomly distributed Bi2O3/V2O5 (denoted as BiV) nanoparticles on monodispersed g-C3N4 nanosheets. The as-prepared ternary Bi2O3/V2O5@g-C3N4 (i.e., BiV@g-C3N4) hybrids demonstrated high specific surface areas with remarkable mesoporous characteristics. The photodegradation efficiencies of the ternary hybrids for PR were 1.2 and 1.8 times higher than those of binary BiV and pristine Bi2O3, respectively, at 50 min irradiation time under simulated solar light irradiation. At the end of the phototreatment, the amount of PR pollutant was reduced to 98.1% in 50 min by using the BiV@g-C3N4 nanocomposites under simulated solar light irradiation and more efficient for photocatalytic H2 production. Based on an electrochemical analysis, we propose a photocatalytic degradation pathway for PR under visible light irradiation. In addition, the BiV@g-C3N4 nanocomposite photocatalysts exhibited both long-term stability and photocatalytic efficiency for the degradation of the PR dye. The excellent photoelectrochemical performance of the BiV@g-C3N4 photocatalysts can be ascribed to their highly dispersed V2O5 and Bi2O3 nanoparticles, mesoporous structure, and high specific surface area (83.75 m2 g-1).

Homomorphisms in C*-ternary algebras and JB*-triples

NASA Astrophysics Data System (ADS)

Park, Choonkil; Rassias, Themistocles M.

2008-01-01

In this paper, we investigate homomorphisms between C*-ternary algebras and derivations on C*-ternary algebras, and homomorphisms between JB*-triples and derivations on JB*-triples, associated with the following Apollonius type additive functional equation

Si/Ti2O3/Reduced Graphene Oxide Nanocomposite Anodes for Lithium-Ion Batteries with Highly Enhanced Cyclic Stability.

PubMed

Park, A Reum; Son, Dae-Yong; Kim, Jung Sub; Lee, Jun Young; Park, Nam-Gyu; Park, Juhyun; Lee, Joong Kee; Yoo, Pil J

2015-08-26

Silicon (Si) has attracted tremendous attention as a high-capacity anode material for next generation Li-ion batteries (LIBs); unfortunately, it suffers from poor cyclic stability due to excessive volume expansion and reduced electrical conductivity after repeated cycles. To circumvent these issues, we propose that Si can be complexed with electrically conductive Ti2O3 to significantly enhance the reversible capacity and cyclic stability of Si-based anodes. We prepared a ternary nanocomposite of Si/Ti2O3/reduced graphene oxide (rGO) using mechanical blending and subsequent thermal reduction of the Si, TiO2 nanoparticles, and rGO nanosheets. As a result, the obtained ternary nanocomposite exhibited a specific capacity of 985 mAh/g and a Coulombic efficiency of 98.4% after 100 cycles at a current density of 100 mA/g. Furthermore, these ternary nanocomposite anodes exhibited outstanding rate capability characteristics, even with an increased current density of 10 A/g. This excellent electrochemical performance can be ascribed to the improved electron and ion transport provided by the Ti2O3 phase within the Si domains and the structurally reinforced conductive framework comprised of the rGO nanosheets. Therefore, it is expected that our approach can also be applied to other anode materials to enable large reversible capacity, excellent cyclic stability, and good rate capability for high-performance LIBs.

First principles study on structural, electronic and optical properties of Ga1-xBxP ternary alloys (x = 0, 0.25, 0.5, 0.75 and 1)

NASA Astrophysics Data System (ADS)

Hoat, D. M.; Rivas Silva, J. F.; Méndez Blas, A.

2018-07-01

The structural, electronic and optical properties of GaP, BP binary compounds and their ternary alloys Ga1-xBxP (x = 0.25, 0.5 and 0.75) have been studied by full-potential linearized augmented plane wave (FP-LAPW) method within the framework of density functional theory (DFT) as implemented in WIEN2k package. Local density approximation (LDA) and generalized gradient approximation (GGA) as proposed by Perdew-Burke-Ernzerhof (PBE), Wu-Cohen (WC) and PBE for solid (PBESol) were used for treatment of exchange-correlation effect in calculations. Additionally, the Tran-Blaha modified Becke-Johnson (mBJ) potential was also employed for electronic and optical calculations due to that it gives very accurate band gap of solids. As B concentration increases, the lattice constant reduces and the energy band gap firstly decreases for small composition x and then it shows increasing trend until pure BP. Our results show that the indirect-direct band gap transition can be reached from x = 0.33. The linear optical properties, such as reflectivity, absorption coefficient, refractive index and optical conductivity of binary compounds and ternary alloys were derived from their calculated complex dielectric function in wide energy range up to 30 eV, and the alloying effect on these properties was also analyzed in detail.

Ternary Surface Monolayers for Ultrasensitive (Zeptomole) Amperometric Detection of Nucleic-Acid Hybridization without Signal Amplification

PubMed Central

Wu, Jie; Campuzano, Susana; Halford, Colin; Haake, David A.; Wang, Joseph

2010-01-01

A ternary surface monolayer, consisting of co-assembled thiolated capture probe (SHCP) mercaptohexanol (MCH) and dithiothreitol (DTT), is shown to offer dramatic improvements in the signal-to-noise characteristics of electrochemical DNA hybridization biosensors based on common self-assembled monolayers (SAMs). Remarkably low detection limits down to 40 zmole (in 4 μL samples) as well as only 1 CFU E. coli per sensor are thus obtained without any additional amplification step in connection to the commonly used horseradish peroxidase/3,3′,5,5′-tetramethylbenzidine (HRP/TMB) system. Such dramatic improvements in the detection limits (compared to common binary alkanethiol interfaces and to most electrochemical DNA sensing strategies without target or signal amplification) are attributed primarily to the remarkably higher resistance to non-specific adsorption. This reflects the highly compact layer (with lower pinhole density) produced by the coupling of the cyclic- and linear-configuration ‘backfillers’ that leads to a remarkably low background noise even in the presence of complex sample matrices. A wide range of surface compositions have been investigated and the ternary mixed monolayer has been systematically optimized. Detailed impedance spectroscopy and cyclic voltammetric studies shed useful insights into the surface coverage. The impressive sensitivity and high specificity of the simple developed methodology indicate great promise for a wide range of nucleic acid testing, including clinical diagnostics, biothreat detection, food safety and forensic analysis. PMID:20883023

Ternary surface monolayers for ultrasensitive (zeptomole) amperometric detection of nucleic acid hybridization without signal amplification.

PubMed

Wu, Jie; Campuzano, Susana; Halford, Colin; Haake, David A; Wang, Joseph

2010-11-01

A ternary surface monolayer, consisting of coassembled thiolated capture probe, mercaptohexanol and dithiothreitol, is shown to offer dramatic improvements in the signal-to-noise characteristics of electrochemical DNA hybridization biosensors based on common self-assembled monolayers. Remarkably low detection limits down to 40 zmol (in 4 μL samples) as well as only 1 CFU Escherichia coli per sensor are thus obtained without any additional amplification step in connection to the commonly used horseradish peroxidase/3,3',5,5'-tetramethylbenzidine system. Such dramatic improvements in the detection limits (compared to those of common binary alkanethiol interfaces and to those of most electrochemical DNA sensing strategies without target or signal amplification) are attributed primarily to the remarkably higher resistance to nonspecific adsorption. This reflects the highly compact layer (with lower pinhole density) produced by the coupling of the cyclic- and linear-configuration "backfillers" that leads to a remarkably low background noise even in the presence of complex sample matrixes. A wide range of surface compositions have been investigated, and the ternary mixed monolayer has been systematically optimized. Detailed impedance spectroscopy and cyclic voltammetric studies shed useful insights into the surface coverage. The impressive sensitivity and high specificity of the simple developed methodology indicate great promise for a wide range of nucleic acid testing, including clinical diagnostics, biothreat detection, food safety, and forensic analysis.

Acoustical Studies of L-leucine and L-asparagine in aqueous electrolyte through thermal expansion coefficient

NASA Astrophysics Data System (ADS)

Jajodia, S.; Chimankar, O. P.; Kalambe, A.; Goswami, S. G.

2012-12-01

Amino acids are the building blocks of the proteins; their study provides important information, about the behaviour of larger biomolecules such as proteins. The properties of proteins such as their structure, solubility, denaturation, etc. are greatly influenced by electrolytes. Ultrasonic velocity and density values have been used for evaluation of thermal expansion coefficient and adiabatic compressibility for ternary systems (amino acid/salt + water) namely L-leucine / L-asparagine each in 1.5 M aqueous solution of NaCl used as solvent for various concentrations and at different temperatures (298.15K - 323.15K). Present paper reports the variation of various thermoacoustical parameters such as Moelwyn-Hughes parameter (C1), Beyer's non-linearity parameter (B/A), internal pressure (Pi), fractional free volume (f), available volume (Va), repulsive exponent (n), molecular constant (r), van der Waals' constant (b), Debye temperatue (θD), etc. have been computed from the thermal expansion coefficient with the change of concentration and temperature. The variations of all these parameters have been interpreted in terms of various intermolecular interactions such as strong, weak, charge transfer, complex formation, hydrogen bonding interaction. The structure making and breaking properties of the interacting components existing in proposed ternary systems. It shows the associating and dissociating tendency of the molecules of solute in solvent.The hetromolecular interactions are present in both the ternary systems.

Transcriptional response to muscarinic acetylcholine receptor stimulation: regulation of Egr-1 biosynthesis by ERK, Elk-1, MKP-1, and calcineurin in carbachol-stimulated human neuroblastoma cells.

PubMed

Rössler, Oliver G; Henss, Isabell; Thiel, Gerald

2008-02-01

Carbachol-mediated activation of type M(3) muscarinic acetylcholine receptors induces the biosynthesis of the transcription factor Egr-1 in human SH-SY5Y neuroblastoma cells involving an activation of extracellular signal-regulated protein kinase. Carbachol triggered the phosphorylation of the ternary complex factor Elk-1, a key transcriptional regulator of serum response element-driven gene transcription, and strikingly enhanced the transcriptional activation potential of Elk-1. Chromatin immunoprecipitation experiments revealed that Elk-1 binds in vivo to the 5'-upstream region of the Egr-1 gene in carbachol-stimulated neuroblastoma cells. Together, these data indicate that Elk-1 connects the intracellular signaling cascade elicited by activation of M(3) muscarinic acetylcholine receptors with the transcription of the Egr-1 gene. Lentiviral-mediated expression of either MAP kinase phosphatase-1 (MKP-1) or a constitutively active mutant of calcineurin A inhibited Egr-1 biosynthesis following carbachol stimulation, indicating that these phosphatases function as shut-off devices of muscarinic acetylcholine receptor signaling. Additionally, carbachol stimulation increased transcription of a chromatin-embedded collagenase promoter/reporter gene, showing that AP-1 activity is enhanced in carbachol-stimulated neuroblastoma. Expression experiments revealed that both MKP-1 and a constitutively active mutant of calcineurin A impaired carbachol-induced upregulation of AP-1 activity. The fact that carbachol stimulation of neuroblastoma cells activates the transcription factors Egr-1 and AP-1 suggests that changes in the gene expression pattern are an integral part of muscarinic acetylcholine receptor signaling.

Cubilin, a high affinity receptor for fibroblast growth factor 8, is required for cell survival in the developing vertebrate head.

PubMed

Cases, Olivier; Perea-Gomez, Aitana; Aguiar, Diego P; Nykjaer, Anders; Amsellem, Sabine; Chandellier, Jacqueline; Umbhauer, Muriel; Cereghini, Silvia; Madsen, Mette; Collignon, Jérôme; Verroust, Pierre; Riou, Jean-François; Creuzet, Sophie E; Kozyraki, Renata

2013-06-07

Cubilin (Cubn) is a multiligand endocytic receptor critical for the intestinal absorption of vitamin B12 and renal protein reabsorption. During mouse development, Cubn is expressed in both embryonic and extra-embryonic tissues, and Cubn gene inactivation results in early embryo lethality most likely due to the impairment of the function of extra-embryonic Cubn. Here, we focus on the developmental role of Cubn expressed in the embryonic head. We report that Cubn is a novel, interspecies-conserved Fgf receptor. Epiblast-specific inactivation of Cubn in the mouse embryo as well as Cubn silencing in the anterior head of frog or the cephalic neural crest of chick embryos show that Cubn is required during early somite stages to convey survival signals in the developing vertebrate head. Surface plasmon resonance analysis reveals that fibroblast growth factor 8 (Fgf8), a key mediator of cell survival, migration, proliferation, and patterning in the developing head, is a high affinity ligand for Cubn. Cell uptake studies show that binding to Cubn is necessary for the phosphorylation of the Fgf signaling mediators MAPK and Smad1. Although Cubn may not form stable ternary complexes with Fgf receptors (FgfRs), it acts together with and/or is necessary for optimal FgfR activity. We propose that plasma membrane binding of Fgf8, and most likely of the Fgf8 family members Fgf17 and Fgf18, to Cubn improves Fgf ligand endocytosis and availability to FgfRs, thus modulating Fgf signaling activity.

Electrocatalyst for alcohol oxidation at fuel cell anodes

DOEpatents

Adzic, Radoslav [East Setauket, NY; Kowal, Andrzej [Cracow, PL

2011-11-02

In some embodiments a ternary electrocatalyst is provided. The electrocatalyst can be used in an anode for oxidizing alcohol in a fuel cell. In some embodiments, the ternary electrocatalyst may include a noble metal particle having a surface decorated with clusters of SnO.sub.2 and Rh. The noble metal particles may include platinum, palladium, ruthenium, iridium, gold, and combinations thereof. In some embodiments, the ternary electrocatalyst includes SnO.sub.2 particles having a surface decorated with clusters of a noble metal and Rh. Some ternary electrocatalysts include noble metal particles with clusters of SnO.sub.2 and Rh at their surfaces. In some embodiments the electrocatalyst particle cores are nanoparticles. Some embodiments of the invention provide a fuel cell including an anode incorporating the ternary electrocatalyst. In some aspects a method of using ternary electrocatalysts of Pt, Rh, and SnO.sub.2 to oxidize an alcohol in a fuel cell is described.

Spectroscopic evidence for ternary surface complexes in the lead(II)-malonic acid-hematite system

USGS Publications Warehouse

Lenhart, J.J.; Bargar, J.R.; Davis, J.A.

2001-01-01

Using extended X-ray absorption fine structure (EXAFS) and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) measurements, we examined the sorption of Pb(II) to hematite in the presence of malonic acid. Pb LIII-edge EXAFS measurements performed in the presence of malonate indicate the presence of both Fe and C neighbors, suggesting that a major fraction of surface-bound malonate is bonded to adsorbed Pb(II). In the absence of Pb(II), ATR-FTIR measurements of sorbed malonate suggest the formation of more than one malonate surface complex. The dissimilarity of the IR spectrum of malonate sorbed on hematite to those for aqueous malonate suggest at least one of the sorbed malonate species is directly coordinated to surface Fe atoms in an inner-sphere mode. In the presence of Pb, little change is seen in the IR spectrum for sorbed malonate, indicating that geometry of malonate as it coordinates to sorbed Pb(II) adions is similar to the geometry of malonate as it coordinates to Fe in the hematite surface. Fits of the raw EXAFS spectra collected from pH 4 to pH 8 result in average Pb-C distances of 2.98 to 3.14 A??, suggesting the presence of both four- and six-membered Pb-malonate rings. The IR results are consistent with this interpretation. Thus, our results suggest that malonate binds to sorbed Pb(II) adions, forming ternary metal-bridging surface complexes. ?? 2001 Academic Press.

Mutual effects of copper and phosphate on their interaction with γ-Al2O3: combined batch macroscopic experiments with DFT calculations.

PubMed

Ren, Xuemei; Yang, Shitong; Tan, Xiaoli; Chen, Changlun; Sheng, Guodong; Wang, Xiangke

2012-10-30

The mutual effects of Cu(II) and phosphate on their interaction with γ-Al(2)O(3) are investigated by using batch experiments combined with density functional theory (DFT) calculations. The results of batch experiments show that coexisting phosphate promotes the retention of Cu(II) on γ-Al(2)O(3), whereas phosphate retention is not affected by coexisting Cu(II) at low initial phosphate concentrations (≤ 3.6 mg P/L). Cu-phosphate aqueous complexes control Cu(II) retention through the formation of type B ternary surface complexes (where phosphate bridges γ-Al(2)O(3) and Cu(II)) at pH 5.5. This deduction is further supported by the results of DFT calculations. More specifically, the DFT calculation results indicate that the type B ternary surface complexes prefer to form outer-sphere or monodentate inner-sphere binding mode under our experimental conditions. The enhancement of phosphate retention on γ-Al(2)O(3) in the presence of Cu(II) at high initial phosphate concentrations (>3.6 mg P/L) may be attributed to the formation of 1:2 Cu(II)-phosphate species and/or surface precipitates. Understanding the mutual effects of phosphate and Cu(II) on their mobility and transport in mineral/water environments is more realistic to design effective remediation strategies for reducing their negative impacts on aquatic/terrestrial environments. Copyright © 2012 Elsevier B.V. All rights reserved.

Deciphering three beneficial effects of 2,2'-bipyridine-N,N'-dioxide on the luminescence sensitization of lanthanide(III) hexafluoroacetylacetonate ternary complexes.

PubMed

Eliseeva, Svetlana V; Pleshkov, Dmitry N; Lyssenko, Konstantin A; Lepnev, Leonid S; Bünzli, Jean-Claude G; Kuzmina, Natalia P

2011-06-06

Lanthanide hexafluoroacetylacetonate ternary complexes with 2,2'-bipyridine-N,N'-dioxide, [Ln(hfa)(3)(bpyO2)], were synthesized for Ln = Eu, Gd, Tb, and Lu and fully characterized by elemental, thermal, and mass-spectrometric analyses. The X-ray crystal structure of [Eu(hfa)(3)(bpyO2)]·0.5C(6)H(6) reveals an octa-coordinate metal ion lying in a severely distorted trigonal dodecahedron geometry; the Eu-O distances lie in the range 2.36-2.44 Å with no significant difference between hfa(-) and bpyO2. A detailed comparative photophysical investigation has been carried out to determine the exact influence of the introduction of bpyO2 in the inner coordination sphere of the metal ion in replacement of the two water molecules in [Ln(hfa)(3)(H(2)O)(2)]. While this replacement is detrimental for Tb, it leads to a 15-fold increase in the overall quantum yield for Eu. This large improvement originates from (i) a better sensitization efficiency, the ancillary ligand being responsible for 3/4 of the energy transfer, (ii) elimination of nonradiative deactivation pathways through harmonics of O-H vibrations, and (iii) reduction in the radiative lifetime. The latter influence is rarely documented, but it accounts here for a ≈25% increase in the intrinsic quantum yield, so that more attention should be given to this parameter when designing highly luminescent lanthanide complexes. © 2011 American Chemical Society

A GTPase reaction accompanying the rejection of Leu-tRNA2 by UUU-programmed ribosomes. Proofreading of the codon-anticodon interaction by ribosomes.

PubMed

Thompson, R C; Dix, D B; Gerson, R B; Karim, A M

1981-01-10

The characteristics of a GTPase reaction between poly(U)-programmed ribosomes, EFTu . GTP, and the near-cognate aminoacyl (aa)-tRNA, Leu-tRNA Leu 2, have been studied to assess the role of this reaction in proofreading of the codon-anticodon interaction. The reaction resembles the GTPase reaction with cognate aa-tRNAs and EFTu . GTP in its substrate requirements, in its involving EFTu . GTP . aa-tRNA ternary complexes, and in its requiring a free ribosomal A-site. The noncognate reaction differs from the cognate one in that aa-tRNA becomes stably bound to the ribosomes only 5% of the time; it therefore seems best characterized as an abortive enzymatic binding reaction. The rate of reaction is a significant fraction (4%) of that of the cognate aa-tRNA, indicating that recognition of ternary complexes by ribosomes involves a level of error greater than that of translation as a whole. The rejection of the noncognate aa-tRNA following GTP hydrolysis is therefore a vital step in the translation process and fulfills the criteria set for a proofreading reaction. Leu-tRNA Leu 2 which escapes rejection through proofreading, forms a stable complex with the ribosomal A-site, so it appears that the Leu-tRNA2 which was rejected never reached the A-site and that proofreading precedes full A-site binding.

Phenomenological model and phase behavior of saturated and unsaturated lipids and cholesterol.

PubMed

Putzel, G Garbès; Schick, M

2008-11-15

We present a phenomenological theory for the phase behavior of ternary mixtures of cholesterol and saturated and unsaturated lipids, one that describes both liquid and gel phases. It leads to the following description of the mechanism of the phase behavior: In a binary system of the lipids, phase separation occurs when the saturated chains are well ordered, as in the gel phase, simply due to packing effects. In the liquid phase, the saturated ones are not sufficiently well ordered for separation to occur. The addition of cholesterol, however, increases the saturated lipid order to the point that phase separation is once again favorable. Our theory addresses this last mechanism-the means by which cholesterol-mediated ordering of membrane lipids leads to liquid-liquid immiscibility. It produces, for the system above the main chain transition of the saturated lipid, phase diagrams in which there can be liquid-liquid phase separation in the ternary system but not in any of the binary ones, while below that temperature it yields the more common phase diagram in which a gel phase, rich in saturated lipid, appears in addition to the two liquid phases.

Probing the Role of Nascent Helicity in p27 Function as a Cell Cycle Regulator

PubMed Central

Otieno, Steve; Kriwacki, Richard

2012-01-01

p27 regulates the activity of Cdk complexes which are the principal governors of phase transitions during cell division. Members of the p27 family of proteins, which also includes p21 and p57, are called the Cip/Kip cyclin-dependent kinase regulators (CKRs). Interestingly, the Cip/Kip CKRs play critical roles in cell cycle regulation by being intrinsically unstructured, a characteristic contrary to the classical structure-function paradigm. They exhibit nascent helicity which has been localized to a segment referred to as sub-domain LH. The nascent helicity of this sub-domain is conserved and we hypothesize that it is an important determinant of their functional properties. To test this hypothesis, we successfully designed and prepared p27 variants in which domain LH was either more or less helical with respect to the wild-type protein. Thermal denaturation experiments showed that the ternary complexes of the p27 variants bound to Cdk2/Cyclin A were less stable compared to the wild-type complex. Isothermal titration calorimetry experiments showed a decrease in the enthalpy of binding for all the mutants with respect to p27. The free energies of binding varied within a much narrower range. In vitro Cdk2 inhibition assays showed that the p27 variants exhibited disparate inhibitory potencies. Furthermore, when over-expressed in NIH 3T3 mouse fibroblast cells, the less helical p27 variants were less effective in causing cell cycle arrest relative to the wild-type p27. Our results indicate that the nascent helicity of sub-domain LH plays a key role mediating the biological function of p27. PMID:23071750

The cubic ternary complex receptor-occupancy model. III. resurrecting efficacy.

PubMed

Weiss, J M; Morgan, P H; Lutz, M W; Kenakin, T P

1996-08-21

Early work in pharmacology characterized the interaction of receptors and ligands in terms of two parameters, affinity and efficacy, an approach we term the bipartite view. A precise formulation of efficacy only exists for very simple pharmacological models. Here we extend the notion of efficacy to models that incorporate receptor activation and G-protein coupling. Using the cubic ternary complex model, we show that efficacy is not purely a property of the ligand-receptor interaction; it also depends upon the distributional details of the receptor species in the native receptor ensemble. This suggests a distinction between what we call potential efficacy (a vector) and realized efficacy (a scalar). To each receptor species in the native receptor ensemble we assign a part-worth utility; taken together these utilities comprise the potential efficacy vector. Realized efficacy is the expectation of these part-worth utilities with respect to the frequency distribution of receptor species in the native receptor ensemble. In the parlance of statistical decision theory, the binding of a ligand to a receptor ensemble is a random prospect and realized efficacy is the utility of this prospect. We explore the implications that our definition of efficacy has for understanding agonism and in assessing the legitimacy of the bipartite view in pharmacology.

Study on the ternary mixed ligand complex of palladium(II)-aminophylline-fluorescein sodium by resonance Rayleigh scattering, second-order scattering and frequency doubling scattering spectrum and its analytical application.

PubMed

Chen, Peili; Liu, Shaopu; Liu, Zhongfang; Hu, Xiaoli

2011-01-01

The interaction between palladium(II)-aminophylline and fluorescein sodium was investigated by resonance Rayleigh scattering, second-order scattering and frequency doubling scattering spectrum. In pH 4.4 Britton-Robinson (BR) buffer medium, aminophylline (Ami) reacted with palladium(II) to form chelate cation([Pd(Ami)]2+), which further reacted with fluorescein sodium (FS) to form ternary mixed ligand complex [Pd(Ami)(FS)2]. As a result, resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering spectrum (FDS) were enhanced. The maximum scattering wavelengths of [Pd(Ami)(FS)2] were located at 300 nm (RRS), 650 nm (SOS) and 304 nm (FDS). The scattering intensities were proportional to the Ami concentration in a certain range and the detection limits were 7.3 ng mL(-1) (RRS), 32.9 ng mL(-1) (SOS) and 79.1 ng mL(-1) (FDS), respectively. Based on it, the new simple, rapid, and sensitive scattering methods have been proposed to determine Ami in urine and serum samples. Moreover, the formation mechanism of [Pd(Ami)(FS)2] and the reasons for enhancement of RRS were fully discussed. Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.

One-pot, facile fabrication of a Ag3PO4-based ternary Z-scheme photocatalyst with excellent visible-light photoactivity and anti-photocorrosion performance

NASA Astrophysics Data System (ADS)

Xie, Mingyuan; Zhang, Tailiang

2018-04-01

Ag3PO4 can-not be widely used as an efficient photocatalyst in practical applications because of its susceptibility to photocorrosion. In this study, a novel, ternary Z-scheme photocatalytic system containing graphene oxide (GO), Ag3PO4 and SnS2 was fabricated by a one-pot, mild, in-situ precipitation method successfully. Using Rhodamine B (RhB) as the target of elimination, GO/Ag3PO4/SnS2 exhibited outstanding photocatalytic and anti-photocorrosion properties compared with those of Ag3PO4, Ag3PO4/SnS2 and GO/Ag3PO4. RhB was thoroughly degraded over the optimized GO/Ag3PO4/SnS2 nanocomposite after only 15 min under visible-light irradiation; this result is approximately 2.14, 3.33 and 5.83 times faster than that of GO/Ag3PO4, Ag3PO4/SnS2 and Ag3PO4, respectively. After three reuses, the photocatalytic activity of the ternary composite slightly decreased but remained 2.36, 4.08 and 12.70 times higher than those of the reused GO/Ag3PO4, Ag3PO4/SnS2 and Ag3PO4, respectively. In this system, the efficient separation and migration of the photoinduced current carriers in Ag3PO4 was realized through a double Z-scheme electron-transfer mechanism in which the GO nanosheets acted as the photocatalyst and electron mediator, thereby enhancing the photoactivity and stability of Ag3PO4. The present study provides a new perspective for enhancing photocatalytic and anti-photocorrosion performances in perishable photocatalysts for organic sewage and other environmental contamination treatments.

Metal biosorption equilibria in a ternary system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chong, K.H.; Volesky, B.

Equilibrium metal uptake performance of a biosorbent prepared from Ascophyllum nodosum seaweed biomass was studied using aqueous solutions containing copper, cadmium, and zinc ions in binary and ternary mixtures. Triangular equilibrium diagrams can graphically represent all the ternary equilibrium sorption data. Application of the multicomponent Langmuir model to describe the three-metal system revealed its nonideal characteristics, whereby the value of apparent dissociation constants for the respective metals differed for each system. This restricted the prediction of the ternary equilibria from the binary systems. However, some predictions of the ternary system behavior from the model were consistent with experimental data andmore » with conclusions postulated from the three possible binary subsystems.« less

High-field superconductivity in the Nb-Ti-Zr ternary system

NASA Astrophysics Data System (ADS)

Ralls, K. M.; Rose, R. M.; Wulff, J.

1980-06-01

Resistive critical current densities, critical fields, and normal-state electrical resistivities were obtained at 4.2 °K for 55 alloys in the Nb-Ti-Zr ternary alloy system, excepting Ti-Zr binary compositions. The resistive critical field as a function of ternary composition has a saddle point between the Nb-Ti and Nb-Zr binaries, so that ternary alloying in this system is not expected to result in higher critical fields than the binary alloys.

Hydrothermal synthesis of graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite for removal of Cu (II) and methylene blue

NASA Astrophysics Data System (ADS)

Long, Zhihang; Zhan, Yingqing; Li, Fei; Wan, Xinyi; He, Yi; Hou, Chunyan; Hu, Hai

2017-09-01

In this work, highly activated graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite adsorbent was prepared from a simple hydrothermal route by using ferrous sulfate as precursor. For this purpose, the graphene oxide/multiwalled carbon nanotube architectures were formed through the π-π attractions between them, followed by attaching Fe3O4 nanoparticles onto their surface. The structure and composition of as-prepared ternary nanocomposite were characterized by XRD, FTIR, XPS, SEM, TEM, Raman, TGA, and BET. It was found that the resultant porous graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite with large surface area could effectively prevent the π-π stacking interactions between graphene oxide nanosheets and greatly improve sorption sites on the surfaces. Thus, owing to the unique ternary nanocomposite architecture and synergistic effect among various components, as-prepared ternary nanocomposite exhibited high separation efficiency when they were used to remove the Cu (II) and methylene blue from aqueous solutions. Furthermore, the adsorption isotherms of ternary nanocomposite structures for Cu (II) and methylene blue removal fitted the Langmuir isotherm model. This work demonstrated that the graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite was promising as an efficient adsorbent for heavy metal ions and organic dye removal from wastewater in low concentration.

Trialkylphosphine-stabilized copper(I) gallium(III) phenylchalcogenolate complexes: crystal structures and generation of ternary semiconductors by thermolysis.

PubMed

Kluge, Oliver; Krautscheid, Harald

2012-06-18

A series of organometallic trialkylphosphine-stabilized copper gallium phenylchalcogenolate complexes [(R(3)P)(m)Cu(n)Me(2-x)Ga(EPh)(n+x+1)] (R = Me, Et, (i)Pr, (t)Bu; E = S, Se, Te; x = 0, 1) has been prepared and structurally characterized by X-ray diffraction. From their molecular structures three groups of compounds can be distinguished: ionic compounds, ring systems, and cage structures. All these complexes contain one gallium atom bound to one or two methyl groups, whereas the number of copper atoms, and therefore the nuclearity of the complexes, is variable and depends mainly on size and amount of phosphine ligand used in synthesis. The Ga-E bonds are relatively rigid, in contrast to flexible Cu-E bonds. The lengths of the latter are controlled by the coordination number and steric influences. The Ga-E bond lengths depend systematically on the number of methyl groups bound to the gallium atom, with somewhat shorter bonds in monomethyl compounds compared to dimethyl compounds. Quantum chemical computations reproduce this trend and show furthermore that the rotation of one phenyl group around the Ga-E bond is a low energy process with two distinct minima, corresponding to two different conformations found experimentally. Mixtures of different types of chalcogen atoms on molecular scale are possible, and then ligand exchange reactions in solution lead to mixed site occupation. In thermogravimetric studies the complexes were converted into the ternary semiconductors CuGaE(2). The thermolysis reaction is completed at temperatures between 250 and 400 °C, typically with lower temperatures for the heavier chalcogens. Because of significant release of Me(3)Ga during the thermolysis process, and especially in case of copper excess in the precursor complexes, binary copper chalcogenides are obtained as additional thermolysis products. Quaternary semiconductors can be obtained from mixed chalcogen precursors.

Interaction of DNA with Simple and Mixed Ligand Copper(II) Complexes of 1,10-Phenanthrolines as Studied by DNA-Fiber EPR Spectroscopy

PubMed Central

Chikira, Makoto; Ng, Chew Hee; Palaniandavar, Mallayan

2015-01-01

The interaction of simple and ternary Cu(II) complexes of 1,10-phenanthrolines with DNA has been studied extensively because of their various interesting and important functions such as DNA cleavage activity, cytotoxicity towards cancer cells, and DNA based asymmetric catalysis. Such functions are closely related to the DNA binding modes of the complexes such as intercalation, groove binding, and electrostatic surface binding. A variety of spectroscopic methods have been used to study the DNA binding mode of the Cu(II) complexes. Of all these methods, DNA-fiber electron paramagnetic resonance (EPR) spectroscopy affords unique information on the DNA binding structures of the complexes. In this review we summarize the results of our DNA-fiber EPR studies on the DNA binding structure of the complexes and discuss them together with the data accumulated by using other measurements. PMID:26402668

Fluorescent studies on the interaction of DNA and ternary lanthanide complexes with cinnamic acid-phenanthroline and antibacterial activities testing.

PubMed

Sun, Hui-Juan; Wang, Ai-Ling; Chu, Hai-Bin; Zhao, Yong-Liang

2015-03-01

Twelve lanthanide complexes with cinnamate (cin(-) ) and 1,10-phenanthroline (phen) were synthesized and characterized. Their compositions were assumed to be RE(cin)3 phen (RE(3+)  = La(3+) , Pr(3+) , Nd(3+) , Sm(3+) , Eu(3+) , Gd(3+) , Tb(3+) , Dy(3+) , Ho(3+) , Tm(3+) , Yb(3+) , Lu(3+) ). The interaction mode between the complexes and DNA was investigated by fluorescence quenching experiment. The results indicated the complexes could bind to DNA and the main binding mode is intercalative binding. The fluorescence quenching constants of the complexes increased from La(cin)3 phen to Lu(cin)3 phen. Additionally, the antibacterial activity testing showed that the complexes exhibited excellent antibacterial ability against Escherichia coli, and the changes of antibacterial ability are in agreement with that of the fluorescence quenching constants. Copyright © 2014 John Wiley & Sons, Ltd.

Capacitive Detection of Low-Enthalpy, Higher-Order Phase Transitions in Synthetic and Natural Composition Lipid Membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, Graham J.; Heberle, Frederick A.; Seinfeld, Jason S.

In-plane lipid organization and phase separation in natural membranes play key roles in regulating many cellular processes. Highly cooperative, first-order phase transitions in model membranes consisting of few lipid components are well understood and readily detectable via calorimetry, densitometry, and fluorescence. However, far less is known about natural membranes containing numerous lipid species and high concentrations of cholesterol, for which thermotropic transitions are undetectable by the above-mentioned techniques. We demonstrate that membrane capacitance is highly sensitive to low-enthalpy thermotropic transitions taking place in complex lipid membranes. Specifically, we measured the electrical capacitance as a function of temperature for droplet interfacemore » bilayer model membranes of increasing compositional complexity, namely, (a) a single lipid species, (b) domain-forming ternary mixtures, and (c) natural brain total lipid extract (bTLE). We observed that, for single-species lipid bilayers and some ternary compositions, capacitance exhibited an abrupt, temperature-dependent change that coincided with the transition detected by other techniques. In addition, capacitance measurements revealed transitions in mixed-lipid membranes that were not detected by the other techniques. Most notably, capacitance measurements of bTLE bilayers indicated a transition at ~38 °C not seen with any other method. Likewise, capacitance measurements detected transitions in some well-studied ternary mixtures that, while known to yield coexisting lipid phases, are not detected with calorimetry or densitometry. These results indicate that capacitance is exquisitely sensitive to low-enthalpy membrane transitions because of its sensitivity to changes in bilayer thickness that occur when lipids and excess solvent undergo subtle rearrangements near a phase transition. Our findings also suggest that heterogeneity confers stability to natural membranes that function near transition temperatures by preventing unwanted defects and macroscopic demixing associated with high-enthalpy transitions commonly found in simpler mixtures.« less

Capacitive Detection of Low-Enthalpy, Higher-Order Phase Transitions in Synthetic and Natural Composition Lipid Membranes

DOE PAGES

Taylor, Graham J.; Heberle, Frederick A.; Seinfeld, Jason S.; ...

2017-08-15

In-plane lipid organization and phase separation in natural membranes play key roles in regulating many cellular processes. Highly cooperative, first-order phase transitions in model membranes consisting of few lipid components are well understood and readily detectable via calorimetry, densitometry, and fluorescence. However, far less is known about natural membranes containing numerous lipid species and high concentrations of cholesterol, for which thermotropic transitions are undetectable by the above-mentioned techniques. We demonstrate that membrane capacitance is highly sensitive to low-enthalpy thermotropic transitions taking place in complex lipid membranes. Specifically, we measured the electrical capacitance as a function of temperature for droplet interfacemore » bilayer model membranes of increasing compositional complexity, namely, (a) a single lipid species, (b) domain-forming ternary mixtures, and (c) natural brain total lipid extract (bTLE). We observed that, for single-species lipid bilayers and some ternary compositions, capacitance exhibited an abrupt, temperature-dependent change that coincided with the transition detected by other techniques. In addition, capacitance measurements revealed transitions in mixed-lipid membranes that were not detected by the other techniques. Most notably, capacitance measurements of bTLE bilayers indicated a transition at ~38 °C not seen with any other method. Likewise, capacitance measurements detected transitions in some well-studied ternary mixtures that, while known to yield coexisting lipid phases, are not detected with calorimetry or densitometry. These results indicate that capacitance is exquisitely sensitive to low-enthalpy membrane transitions because of its sensitivity to changes in bilayer thickness that occur when lipids and excess solvent undergo subtle rearrangements near a phase transition. Our findings also suggest that heterogeneity confers stability to natural membranes that function near transition temperatures by preventing unwanted defects and macroscopic demixing associated with high-enthalpy transitions commonly found in simpler mixtures.« less

Novel Strategy for Photopatterning Emissive Polymer Brushes for Organic Light Emitting Diode Applications

PubMed Central

2017-01-01

A light-mediated methodology to grow patterned, emissive polymer brushes with micron feature resolution is reported and applied to organic light emitting diode (OLED) displays. Light is used for both initiator functionalization of indium tin oxide and subsequent atom transfer radical polymerization of methacrylate-based fluorescent and phosphorescent iridium monomers. The iridium centers play key roles in photocatalyzing and mediating polymer growth while also emitting light in the final OLED structure. The scope of the presented procedure enables the synthesis of a library of polymers with emissive colors spanning the visible spectrum where the dopant incorporation, position of brush growth, and brush thickness are readily controlled. The chain-ends of the polymer brushes remain intact, affording subsequent chain extension and formation of well-defined diblock architectures. This high level of structure and function control allows for the facile preparation of random ternary copolymers and red–green–blue arrays to yield white emission. PMID:28691078

Water-Vapor-Mediated Close-Spaced Vapor Transport Growth of Epitaxial Gallium Indium Phosphide Films on Gallium Arsenide Substrates

DOE PAGES

Greenaway, Ann L.; Bachman, Benjamin F.; Boucher, Jason W.; ...

2018-01-12

Ga 1–xIn xP is a technologically important III–V ternary semiconductor widely utilized in commercial and record-efficiency solar cells. We report the growth of Ga 1–xIn xP by water-vapor-mediated close-spaced vapor transport. Because growth of III–V semiconductors in this system is controlled by diffusion of metal oxide species, we find that congruent transport from the mixed powder source requires complete annealing to form a single alloy phase. Growth from a fully alloyed source at water vapor concentrations of ~7000 ppm in H 2 at 850 °C affords smooth films with electron mobility of 1070 cm 2 V –1 s –1 andmore » peak internal quantum efficiency of ~90% for carrier collection in a nonaqueous photoelectrochemical test cell.« less

Novel Strategy for Photopatterning Emissive Polymer Brushes for Organic Light Emitting Diode Applications.

PubMed

Page, Zachariah A; Narupai, Benjaporn; Pester, Christian W; Bou Zerdan, Raghida; Sokolov, Anatoliy; Laitar, David S; Mukhopadhyay, Sukrit; Sprague, Scott; McGrath, Alaina J; Kramer, John W; Trefonas, Peter; Hawker, Craig J

2017-06-28

A light-mediated methodology to grow patterned, emissive polymer brushes with micron feature resolution is reported and applied to organic light emitting diode (OLED) displays. Light is used for both initiator functionalization of indium tin oxide and subsequent atom transfer radical polymerization of methacrylate-based fluorescent and phosphorescent iridium monomers. The iridium centers play key roles in photocatalyzing and mediating polymer growth while also emitting light in the final OLED structure. The scope of the presented procedure enables the synthesis of a library of polymers with emissive colors spanning the visible spectrum where the dopant incorporation, position of brush growth, and brush thickness are readily controlled. The chain-ends of the polymer brushes remain intact, affording subsequent chain extension and formation of well-defined diblock architectures. This high level of structure and function control allows for the facile preparation of random ternary copolymers and red-green-blue arrays to yield white emission.

Water-Vapor-Mediated Close-Spaced Vapor Transport Growth of Epitaxial Gallium Indium Phosphide Films on Gallium Arsenide Substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenaway, Ann L.; Bachman, Benjamin F.; Boucher, Jason W.

Ga 1–xIn xP is a technologically important III–V ternary semiconductor widely utilized in commercial and record-efficiency solar cells. We report the growth of Ga 1–xIn xP by water-vapor-mediated close-spaced vapor transport. Because growth of III–V semiconductors in this system is controlled by diffusion of metal oxide species, we find that congruent transport from the mixed powder source requires complete annealing to form a single alloy phase. Growth from a fully alloyed source at water vapor concentrations of ~7000 ppm in H 2 at 850 °C affords smooth films with electron mobility of 1070 cm 2 V –1 s –1 andmore » peak internal quantum efficiency of ~90% for carrier collection in a nonaqueous photoelectrochemical test cell.« less

Ternary and Quaternary Composition Diagrams: An Overview of the Subject.

ERIC Educational Resources Information Center

MacCarthy, Patrick

1983-01-01

Reviews graphical methods for representing ternary and quaternary systems, focusing on use of triangular composition diagrams. Examines some of the relevant geometry of triangles in general, showing that right isosceles triangles possess some very advantageous features for representing ternary systems. (JN)

Pb-free Sn-Ag-Cu ternary eutectic solder

DOEpatents

Anderson, Iver E.; Yost, Frederick G.; Smith, John F.; Miller, Chad M.; Terpstra, Robert L.

1996-06-18

A Pb-free solder includes a ternary eutectic composition consisting essentially of about 93.6 weight % Sn-about 4.7 weight % Ag-about 1.7 weight % Cu having a eutectic melting temperature of about 217.degree. C. and variants of the ternary composition wherein the relative concentrations of Sn, Ag, and Cu deviate from the ternary eutectic composition to provide a controlled melting temperature range (liquid-solid "mushy" zone) relative to the eutectic melting temperature (e.g. up to 15.degree. C. above the eutectic melting temperature).

Pb-free Sn-Ag-Cu ternary eutectic solder

DOEpatents

Anderson, I.E.; Yost, F.G.; Smith, J.F.; Miller, C.M.; Terpstra, R.L.

1996-06-18

A Pb-free solder includes a ternary eutectic composition consisting essentially of about 93.6 weight % Sn-about 4.7 weight % Ag-about 1.7 weight % Cu having a eutectic melting temperature of about 217 C and variants of the ternary composition wherein the relative concentrations of Sn, Ag, and Cu deviate from the ternary eutectic composition to provide a controlled melting temperature range (liquid-solid ``mushy`` zone) relative to the eutectic melting temperature (e.g. up to 15 C above the eutectic melting temperature). 5 figs.

Ternary particle yields in 249Cf(nth,f)

NASA Astrophysics Data System (ADS)

Tsekhanovich, I.; Büyükmumcu, Z.; Davi, M.; Denschlag, H. O.; Gönnenwein, F.; Boulyga, S. F.

2003-03-01

An experiment measuring ternary particle yields in 249Cf(nth,f) was carried out at the high flux reactor of the Institut Laue-Langevin using the Lohengrin recoil mass separator. Parameters of energy distributions were determined for 27 ternary particles up to 30Mg and their yields were calculated. The yields of 17 further ternary particles were estimated on the basis of the systematics developed. The heaviest particles observed in the experiment are 37Si and 37S; their possible origin is discussed.

Quantitative analyses of bifunctional molecules.

PubMed

Braun, Patrick D; Wandless, Thomas J

2004-05-11

Small molecules can be discovered or engineered to bind tightly to biologically relevant proteins, and these molecules have proven to be powerful tools for both basic research and therapeutic applications. In many cases, detailed biophysical analyses of the intermolecular binding events are essential for improving the activity of the small molecules. These interactions can often be characterized as straightforward bimolecular binding events, and a variety of experimental and analytical techniques have been developed and refined to facilitate these analyses. Several investigators have recently synthesized heterodimeric molecules that are designed to bind simultaneously with two different proteins to form ternary complexes. These heterodimeric molecules often display compelling biological activity; however, they are difficult to characterize. The bimolecular interaction between one protein and the heterodimeric ligand (primary dissociation constant) can be determined by a number of methods. However, the interaction between that protein-ligand complex and the second protein (secondary dissociation constant) is more difficult to measure due to the noncovalent nature of the original protein-ligand complex. Consequently, these heterodimeric compounds are often characterized in terms of their activity, which is an experimentally dependent metric. We have developed a general quantitative mathematical model that can be used to measure both the primary (protein + ligand) and secondary (protein-ligand + protein) dissociation constants for heterodimeric small molecules. These values are largely independent of the experimental technique used and furthermore provide a direct measure of the thermodynamic stability of the ternary complexes that are formed. Fluorescence polarization and this model were used to characterize the heterodimeric molecule, SLFpYEEI, which binds to both FKBP12 and the Fyn SH2 domain, demonstrating that the model is useful for both predictive as well as ex post facto analytical applications.

Structural Basis for Dual-Inhibition Mechanism of a Non-Classical Kazal-Type Serine Protease Inhibitor from Horseshoe Crab in Complex with Subtilisin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shenoy, Rajesh T.; Thangamani, Saravanan; Velazquez-Campoy, Adrian

2011-04-26

Serine proteases play a crucial role in host-pathogen interactions. In the innate immune system of invertebrates, multi-domain protease inhibitors are important for the regulation of host-pathogen interactions and antimicrobial activities. Serine protease inhibitors, 9.3-kDa CrSPI isoforms 1 and 2, have been identified from the hepatopancreas of the horseshoe crab, Carcinoscorpius rotundicauda. The CrSPIs were biochemically active, especially CrSPI-1, which potently inhibited subtilisin (Ki=1.43 nM). CrSPI has been grouped with the non-classical Kazal-type inhibitors due to its unusual cysteine distribution. Here we report the crystal structure of CrSPI-1 in complex with subtilisin at 2.6 Å resolution and the results of biophysicalmore » interaction studies. The CrSPI-1 molecule has two domains arranged in an extended conformation. These two domains act as heads that independently interact with two separate subtilisin molecules, resulting in the inhibition of subtilisin activity at a ratio of 1:2 (inhibitor to protease). Each subtilisin molecule interacts with the reactive site loop from each domain of CrSPI-1 through a standard canonical binding mode and forms a single ternary complex. In addition, we propose the substrate preferences of each domain of CrSPI-1. Domain 2 is specific towards the bacterial protease subtilisin, while domain 1 is likely to interact with the host protease, Furin. Elucidation of the structure of the CrSPI-1: subtilisin (1:2) ternary complex increases our understanding of host-pathogen interactions in the innate immune system at the molecular level and provides new strategies for immunomodulation.« less

Interaction investigations of HipA binding to HipB dimer and HipB dimer + DNA complex: a molecular dynamics simulation study.

PubMed

Li, Chaoqun; Wang, Yaru; Wang, Yan; Chen, Guangju

2013-11-01

We carried out molecular dynamics simulations and free energy calculations for a series of ternary and diplex models for the HipA protein, HipB dimer, and DNA molecule to address the mechanism of HipA sequestration and the binding order of events from apo HipB/HipA to 2HipA + HipB dimer + DNA complex. The results revealed that the combination of DNA with the HipB dimer is energetically favorable for the combination of HipB dimer with HipA protein. The binding of DNA to HipB dimer induces a long-range allosteric communication from the HipB2 -DNA interface to the HipA-HipB2 interface, which involves the closeness of α1 helices of HipB dimer to HipA protein and formations of extra hydrogen bonds in the HipA-HipB2 interface through the extension of α2/3 helices in the HipB dimer. These simulated results suggested that the DNA molecule, as a regulative media, modulates the HipB dimer conformation, consequently increasing the interactions of HipB dimer with the HipA proteins, which explains the mechanism of HipA sequestration reported by the previous experiment. Simultaneously, these simulations also explored that the thermodynamic binding order in a simulated physiological environment, that is, the HipB dimer first bind to DNA to form HipB dimer + DNA complex, then capturing strongly the HipA proteins to form a ternary complex, 2HipA + HipB dimer + DNA, for sequestrating HipA in the nucleoid. Copyright © 2013 John Wiley & Sons, Ltd.

Canonical Initiation Factor Requirements of the Myc Family of Internal Ribosome Entry Segments▿ †

PubMed Central

Spriggs, Keith A.; Cobbold, Laura C.; Jopling, Catherine L.; Cooper, Rebecca E.; Wilson, Lindsay A.; Stoneley, Mark; Coldwell, Mark J.; Poncet, Didier; Shen, Ya-Ching; Morley, Simon J.; Bushell, Martin; Willis, Anne E.

2009-01-01

Initiation of protein synthesis in eukaryotes requires recruitment of the ribosome to the mRNA and its translocation to the start codon. There are at least two distinct mechanisms by which this process can be achieved; the ribosome can be recruited either to the cap structure at the 5′ end of the message or to an internal ribosome entry segment (IRES), a complex RNA structural element located in the 5′ untranslated region (5′-UTR) of the mRNA. However, it is not well understood how cellular IRESs function to recruit the ribosome or how the 40S ribosomal subunits translocate from the initial recruitment site on the mRNA to the AUG initiation codon. We have investigated the canonical factors that are required by the IRESs found in the 5′-UTRs of c-, L-, and N-myc, using specific inhibitors and a tissue culture-based assay system, and have shown that they differ considerably in their requirements. The L-myc IRES requires the eIF4F complex and the association of PABP and eIF3 with eIF4G for activity. The minimum requirements of the N- and c-myc IRESs are the C-terminal domain of eIF4G to which eIF4A is bound and eIF3, although interestingly this protein does not appear to be recruited to the IRES RNA via eIF4G. Finally, our data show that all three IRESs require a ternary complex, although in contrast to c- and L-myc IRESs, the N-myc IRES has a lesser requirement for a ternary complex. PMID:19124605

Structural determinants of ligand binding in the ternary complex of human ileal bile acid binding protein with glycocholate and glycochenodeoxycholate obtained from solution NMR.

PubMed

Horváth, Gergő; Bencsura, Ákos; Simon, Ágnes; Tochtrop, Gregory P; DeKoster, Gregory T; Covey, Douglas F; Cistola, David P; Toke, Orsolya

2016-02-01

Besides aiding digestion, bile salts are important signal molecules exhibiting a regulatory role in metabolic processes. Human ileal bile acid binding protein (I-BABP) is an intracellular carrier of bile salts in the epithelial cells of the distal small intestine and has a key role in the enterohepatic circulation of bile salts. Positive binding cooperativity combined with site selectivity of glycocholate and glycochenodeoxycholate, the two most abundant bile salts in the human body, make human I-BABP a unique member of the family of intracellular lipid binding proteins. Solution NMR structure of the ternary complex of human I-BABP with glycocholate and glycochenodeoxycholate reveals an extensive network of hydrogen bonds and hydrophobic interactions stabilizing the bound bile salts. Conformational changes accompanying bile salt binding affects four major regions in the protein including the C/D, E/F and G/H loops as well as the helical segment. Most of these protein regions coincide with a previously described network of millisecond time scale fluctuations in the apo protein, a motion absent in the bound state. Comparison of the heterotypic doubly ligated complex with the unligated form provides further evidence of a conformation selection mechanism of ligand entry. Structural and dynamic aspects of human I-BABP-bile salt interaction are discussed and compared with characteristics of ligand binding in other members of the intracellular lipid binding protein family. The coordinates of the 10 lowest energy structures of the human I-BABP : GCDA : GCA complex as well as the distance restraints used to calculate the final ensemble have been deposited in the Brookhaven Protein Data Bank with accession number 2MM3. © 2015 FEBS.

Prediction of novel stable Fe-V-Si ternary phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Manh Cuong; Chen, Chong; Zhao, Xin

Genetic algorithm searches based on a cluster expansion model are performed to search for stable phases of Fe-V-Si ternary. Here, we identify a new thermodynamically, dynamically and mechanically stable ternary phase of Fe 5V 2Si with 2 formula units in a tetragonal unit cell. The formation energy of this new ternary phase is -36.9 meV/atom below the current ternary convex hull. The magnetic moment of Fe in the new structure varies from -0.30-2.52 μ B depending strongly on the number of Fe nearest neighbors. The total magnetic moment is 10.44 μ B/unit cell for new Fe 5V 2Si structure andmore » the system is ordinarily metallic.« less

MnO2 Nanorods Intercalating Graphene Oxide/Polyaniline Ternary Composites for Robust High-Performance Supercapacitors

NASA Astrophysics Data System (ADS)

Han, Guangqiang; Liu, Yun; Zhang, Lingling; Kan, Erjun; Zhang, Shaopeng; Tang, Jian; Tang, Weihua

2014-04-01

New ternary composites of MnO2 nanorods, polyaniline (PANI) and graphene oxide (GO) have been prepared by a two-step process. The 100 nm-long MnO2 nanorods with a diameter ~20 nm are conformably coated with PANI layers and fastened between GO layers. The MnO2 nanorods incorporated ternary composites electrode exhibits significantly increased specific capacitance than PANI/GO binary composite in supercapacitors. The ternary composite with 70% MnO2 exhibits a highest specific capacitance reaching 512 F/g and outstanding cycling performance, with ~97% capacitance retained over 5000 cycles. The ternary composite approach offers an effective solution to enhance the device performance of metal-oxide based supercapacitors for long cycling applications.

Prediction of novel stable Fe-V-Si ternary phase

DOE PAGES

Nguyen, Manh Cuong; Chen, Chong; Zhao, Xin; ...

2018-10-28

Genetic algorithm searches based on a cluster expansion model are performed to search for stable phases of Fe-V-Si ternary. Here, we identify a new thermodynamically, dynamically and mechanically stable ternary phase of Fe 5V 2Si with 2 formula units in a tetragonal unit cell. The formation energy of this new ternary phase is -36.9 meV/atom below the current ternary convex hull. The magnetic moment of Fe in the new structure varies from -0.30-2.52 μ B depending strongly on the number of Fe nearest neighbors. The total magnetic moment is 10.44 μ B/unit cell for new Fe 5V 2Si structure andmore » the system is ordinarily metallic.« less

Single Crystal Fibers of Yttria-Stabilized Cubic Zirconia with Ternary Oxide Additions

NASA Technical Reports Server (NTRS)

Ritzert, F. J.; Yun, H. M.; Miner, R. V.

1997-01-01

Single crystal fibers of yttria (Y2O3)-stabilized cubic zirconia, (ZrO2) with ternary oxide additions were grown using the laser float zone fiber processing technique. Ternary additions to the ZrO2-Y2O3 binary system were studied aimed at increasing strength while maintaining the high coefficient of thermal expansion of the binary system. Statistical methods aided in identifying the most promising ternary oxide candidate (Ta2O5, Sc2O3, and HfO2) and optimum composition. The yttria, range investigated was 14 to 24 mol % and the ternary oxide component ranged from 1 to 5 mol %. Hafnium oxide was the most promising ternary oxide component based on 816 C tensile strength results and ease of fabrication. The optimum composition for development was 81 ZrO2-14 Y203-5 HfO2 based upon the same elevated temperature strength tests. Preliminary results indicate process improvements could improve the fiber performance. We also investigated the effect of crystal orientation on strength.

Sorption of norfloxacin, sulfamerazine and oxytetracycline by KOH-modified biochar under single and ternary systems.

PubMed

Luo, Jiwei; Li, Xue; Ge, Chengjun; Müller, Karin; Yu, Huamei; Huang, Peng; Li, Jiatong; Tsang, Daniel C W; Bolan, Nanthi S; Rinklebe, Jörg; Wang, Hailong

2018-05-08

Pollution of water by single antibiotics has been investigated in depth. However, in reality, a wide range of different contaminants is often mixed in the aquatic environment (contaminant cocktail). Here, single and competitive sorption dynamics of ionizable norfloxacin (NOR), sulfamerazine (SMR) and oxytetracycline (OTC) by both pristine and modified biochars were investigated. Sorption kinetics of the three antibiotics was faster in ternary-solute than single-solute system. Sorption efficiency was enhanced in the competitive system for NOR by the pristine biochar, and for OTC by both the pristine biochar and the modified biochar, while SMR sorption by the pristine biochar and the KOH-modified biochar was inhibited. Sorption was governed by electrostatic interactions, π-π EDA and H-bonds for antibiotics sorption by biochar. SMR and OTC sorption by biochar was influenced by cation bridging and surface complexation, respectively. This research finding will guide the development of treatment procedures for water polluted by multiple antibiotics. Copyright © 2018 Elsevier Ltd. All rights reserved.

Pourbaix diagrams for the ternary system of iron-chromium-nickel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beverskog, B.; Puigdomenech, I.

1999-11-01

Pourbaix diagrams (potential-pH diagrams) for the ternary system of Fe-Cr-Ni at 25 C to 300 C were calculated. Extrapolation of thermochemical data to elevated temperatures was performed with the revised model of Helgeson-Kirkham-Flowers, which also allows uncharged aqueous complexes to be handled. The large stability of the bimetallic spinel oxides (trevorite [NiFe{sub 2}O{sub 4}], chromite [FeCr{sub 2}O{sub 4}], and nichromite [NiCr{sub 2}O{sub 4}]) is shown by their predominance areas on top of those for the single metal Pourbaix diagrams. NiFe{sub 2}O{sub 4} had the largest stability area of the spinels, and it covered the entire potential range for the stabilitymore » of water at intermediate pH. FeCr{sub 2}O{sub 4} had the smallest stability area and was the least stable of the bimetallic spinels. Results were discussed in connection with the different chemistries used in nuclear power reactors of the boiling water type.« less

Synthesis and magnetic property of T4 virus-supported gold-coated iron ternary nanocomposite

NASA Astrophysics Data System (ADS)

Xu, Ziming; Sun, Hongjing; Gao, Faming; Hou, Li; Li, Na

2012-12-01

Herein, we present a novel method based on the use of the symmetrical T4 bacteriophage capsid as a scaffold for preparing the gold-coated iron ternary core/shell nanostructure. Results showed that the thick gold shell was obtained to effectively protect Fe core from oxidation. Magnetic measurements showed that the nanocomposites were superparamagnetic at room temperature with a blocking temperature of about 35 K. At 3 K, its coercivity of 1142.86 Oe was larger than the existing experimental values. The magnetic property of Au/T4 was also tested, demonstrating the source of the magnetic sample arising from the Fe core only. The absorption spectrum of the Fe@Au/T4 complex was measured and compared with gold/virus. Different thickness gold shells were controlled in the synthesis by tuning the Au salt addition. On the basis of results and discussion, we further speculated the general growing mechanism of the template-supported Fe@Au process.

Ternary structure reveals mechanism of a membrane diacylglycerol kinase

DOE PAGES

Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; ...

2015-12-17

Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternarymore » structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. As a result, the active site architecture shows clear evidence of having arisen by convergent evolution.« less

Multistate Memristive Tantalum Oxide Devices for Ternary Arithmetic

PubMed Central

Kim, Wonjoo; Chattopadhyay, Anupam; Siemon, Anne; Linn, Eike; Waser, Rainer; Rana, Vikas

2016-01-01

Redox-based resistive switching random access memory (ReRAM) offers excellent properties to implement future non-volatile memory arrays. Recently, the capability of two-state ReRAMs to implement Boolean logic functionality gained wide interest. Here, we report on seven-states Tantalum Oxide Devices, which enable the realization of an intrinsic modular arithmetic using a ternary number system. Modular arithmetic, a fundamental system for operating on numbers within the limit of a modulus, is known to mathematicians since the days of Euclid and finds applications in diverse areas ranging from e-commerce to musical notations. We demonstrate that multistate devices not only reduce the storage area consumption drastically, but also enable novel in-memory operations, such as computing using high-radix number systems, which could not be implemented using two-state devices. The use of high radix number system reduces the computational complexity by reducing the number of needed digits. Thus the number of calculation operations in an addition and the number of logic devices can be reduced. PMID:27834352

Multistate Memristive Tantalum Oxide Devices for Ternary Arithmetic.

PubMed

Kim, Wonjoo; Chattopadhyay, Anupam; Siemon, Anne; Linn, Eike; Waser, Rainer; Rana, Vikas

2016-11-11

Redox-based resistive switching random access memory (ReRAM) offers excellent properties to implement future non-volatile memory arrays. Recently, the capability of two-state ReRAMs to implement Boolean logic functionality gained wide interest. Here, we report on seven-states Tantalum Oxide Devices, which enable the realization of an intrinsic modular arithmetic using a ternary number system. Modular arithmetic, a fundamental system for operating on numbers within the limit of a modulus, is known to mathematicians since the days of Euclid and finds applications in diverse areas ranging from e-commerce to musical notations. We demonstrate that multistate devices not only reduce the storage area consumption drastically, but also enable novel in-memory operations, such as computing using high-radix number systems, which could not be implemented using two-state devices. The use of high radix number system reduces the computational complexity by reducing the number of needed digits. Thus the number of calculation operations in an addition and the number of logic devices can be reduced.

Multistate Memristive Tantalum Oxide Devices for Ternary Arithmetic

NASA Astrophysics Data System (ADS)

Kim, Wonjoo; Chattopadhyay, Anupam; Siemon, Anne; Linn, Eike; Waser, Rainer; Rana, Vikas

2016-11-01

Redox-based resistive switching random access memory (ReRAM) offers excellent properties to implement future non-volatile memory arrays. Recently, the capability of two-state ReRAMs to implement Boolean logic functionality gained wide interest. Here, we report on seven-states Tantalum Oxide Devices, which enable the realization of an intrinsic modular arithmetic using a ternary number system. Modular arithmetic, a fundamental system for operating on numbers within the limit of a modulus, is known to mathematicians since the days of Euclid and finds applications in diverse areas ranging from e-commerce to musical notations. We demonstrate that multistate devices not only reduce the storage area consumption drastically, but also enable novel in-memory operations, such as computing using high-radix number systems, which could not be implemented using two-state devices. The use of high radix number system reduces the computational complexity by reducing the number of needed digits. Thus the number of calculation operations in an addition and the number of logic devices can be reduced.

Motor impairments, striatal degeneration, and altered dopamine-glutamate interplay in mice lacking PSD-95.

PubMed

Zhang, Jingping; Saur, Taixiang; Duke, Angela N; Grant, Seth G N; Platt, Donna M; Rowlett, James K; Isacson, Ole; Yao, Wei-Dong

2014-01-01

Excessive activation of the N-methyl-d-aspartate (NMDA) receptor and the neurotransmitter dopamine (DA) mediate neurotoxicity and neurodegeneration under many neurological conditions, including Huntington's disease (HD), an autosomal dominant neurodegenerative disease characterized by the preferential loss of medium spiny projection neurons (MSNs) in the striatum. PSD-95 is a major scaffolding protein in the postsynaptic density (PSD) of dendritic spines, where a classical role for PSD-95 is to stabilize glutamate receptors at sites of synaptic transmission. Our recent studies indicate that PSD-95 also interacts with the D1 DA receptor localized in spines and negatively regulates spine D1 signaling. Moreover, PSD-95 forms ternary protein complexes with D1 and NMDA receptors, and plays a role in limiting the reciprocal potentiation between both receptors from being escalated. These studies suggest a neuroprotective role for PSD-95. Here we show that mice lacking PSD-95, resulting from genetic deletion of the GK domain of PSD-95 (PSD-95-ΔGK mice), sporadically develop progressive neurological impairments characterized by hypolocomotion, limb clasping, and loss of DARPP-32-positive MSNs. Electrophysiological experiments indicated that NMDA receptors in mutant MSNs were overactive, suggested by larger, NMDA receptor-mediated miniature excitatory postsynaptic currents (EPSCs) and higher ratios of NMDA- to AMPA-mediated corticostriatal synaptic transmission. In addition, NMDA receptor currents in mutant cortical neurons were more sensitive to potentiation by the D1 receptor agonist SKF81297. Finally, repeated administration of the psychostimulant cocaine at a dose regimen not producing overt toxicity-related phenotypes in normal mice reliably converted asymptomatic mutant mice to clasping symptomatic mice. These results support the hypothesis that deletion of PSD-95 in mutant mice produces concomitant overactivation of both D1 and NMDA receptors that makes neurons more susceptible to NMDA excitotoxicity, causing neuronal damage and neurological impairments. Understanding PSD-95-dependent neuroprotective mechanisms may help elucidate processes underlying neurodegeneration in HD and other neurological disorders.

Sequential character of low-energy ternary and quaternary nuclear fission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru; Bulychev, A. O.

2016-09-15

An analysis of low-energy true ternary (quaternary) nuclear fission leads to the conclusion that these fission modes have a sequential two-step (three-step) character such that the emission of a third particle (third and fourth particles) and the separation of fission fragments occur at distinctly different instants, in contrast to the simultaneous emergence of all fission products in the case of onestep ternary (quaternary) fission. This conclusion relies on the following arguments. First, the emission of a third particle (third and fourth particles) from a fissile nucleus is due to a nonevaporative mechanism associated with a nonadiabatic character of the collectivemore » deformation motion of this nucleus at the stages preceding its scission. Second, the axial symmetry of the deformed fissile compound nucleus and the direction of its symmetry axis both remain unchanged at all stages of ternary (quaternary) fission. This circumstancemakes it possible to explain themechanism of the appearance of observed anisotropies and T — odd asymmeries in the angular distributions of products of ternary (quaternary) nuclear fission. Third, the T —odd asymmetry discovered experimentally in ternary nuclear fission induced by cold polarized neutrons obeys the T —invariance condition only in the case of a sequential two-step (three-step) character of true ternary (quaternary) nuclear fission. At the same time, this asymmetry is not a T —invariant quantity in the case of the simultaneous emission of products of true ternary (quaternary) nuclear fission from the fissile compound nucleus.« less

Robust Lys63-Linked Ubiquitination of RIG-I Promotes Cytokine Eruption in Early Influenza B Virus Infection

PubMed Central

Jiang, Jingwen; Fan, Wenhui; Zheng, Weinan; Yu, Meng; Chen, Can; Sun, Lei; Bi, Yuhai; Ding, Chan; Gao, George F.

2016-01-01

ABSTRACT Influenza A and B virus infections both cause a host innate immunity response. Here, we report that the robust production of type I and III interferons (IFNs), IFN-stimulated genes, and proinflammatory factors can be induced by influenza B virus rather than influenza A virus infection in alveolar epithelial (A549) cells during early infection. This response is mainly dependent on the retinoic acid-inducible gene I (RIG-I)-mediated signaling pathway. Infection by influenza B virus promotes intense Lys63-linked ubiquitination of RIG-I, resulting in cytokine eruption. It is known that the influenza A virus NS1 protein (NS1-A) interacts with RIG-I and TRIM25 to suppress the activation of RIG-I-mediated signaling. However, the present results indicate that the influenza B virus NS1 protein (NS1-B) is unable to interact with RIG-I but engages in the formation of a RIG-I/TRIM25/NS1-B ternary complex. Furthermore, we demonstrate that the N-terminal RNA-binding domain (RBD) of NS1-B is responsible for interaction with TRIM25 and that this interaction blocks the inhibitory effect of the NS1-B C-terminal effector domain (TED) on RIG-I ubiquitination. Our findings reveal a novel mechanism for the host cytokine response to influenza B virus infection through regulatory interplay between host and viral proteins. IMPORTANCE Influenza B virus generally causes local mild epidemics but is occasionally lethal to individuals. Existing studies describe the broad characteristics of influenza B virus epidemiology and pathology. However, to develop better prevention and treatments for the disease, determining the concrete molecular mechanisms of pathogenesis becomes pivotal to understand how the host reacts to the challenge of influenza B virus. Thus, we aimed to characterize the host innate immune response to influenza B virus infection. Here, we show that vigorous Lys63-linked ubiquitination of RIG-I and cytokine eruption dependent on RIG-I-mediated signal transduction are induced by virus infection. Additionally, TRIM25 positively regulates RIG-I-mediated signaling by ablating the inhibitory function of NS1-B on RIG-I ubiquitination. PMID:27122586

Effect of humic acid & bacterial exudates on sorption-desorption interactions of 90Sr with brucite.

PubMed

Ashworth, Hollie; Abrahamsen-Mills, Liam; Bryan, Nick; Foster, Lynn; Lloyd, Jonathan R; Kellet, Simon; Heath, Sarah

2018-05-18

One of the nuclear fuel storage ponds at Sellafield (United Kingdom) is open to the air, and has contained a significant inventory of corroded magnox fuel and sludge for several decades. As a result, some fission products have also been released into solution. 90Sr is known to constitute a small mass of the radionuclides present in the pond, but due to its solubility and activity, it is at risk of challenging effluent discharge limits. The sludge is predominantly composed of brucite (Mg(OH)2), and organic molecules are known to be present in the pond liquor with occasional algal blooms restricting visibility. Understanding the chemical interactions of these components is important to inform ongoing sludge retrievals and effluent management. Additionally, interactions of radionuclides with organics at high pH will be an important consideration for the evolution of cementitious backfilled disposal sites in the UK. Batch sorption-desorption experiments were performed with brucite, 90Sr and natural organic matter (NOM) (humic acid (HA) and Pseudanabaena catenata cyanobacterial growth supernatant) in both binary and ternary systems at high pH. Ionic strength, pH and order of addition of components were varied. 90Sr was shown not to interact strongly with the bulk brucite surface in binary systems under pH conditions relevant to the pond. HA in both binary and ternary systems demonstrated a strong affinity for the brucite surface. Ternary systems containing HA demonstrated enhanced sorption of 90Sr at pH 11.5 and vice versa, likely via formation of strontium-humate complexes regardless of the order of addition of components. The distribution coefficients show HA sorption to be reversible at all pH values studied, and it appeared to control 90Sr behaviour at pH 11.5. Ternary systems containing cyanobacterial supernatant demonstrated a difference in 90Sr behaviour when the culture had been subjected to irradiation in the first stages of its growth.

Investigating the discrimination potential of linear and nonlinear spectral multivariate calibrations for analysis of phenolic compounds in their binary and ternary mixtures and calculation pKa values.

PubMed

Rasouli, Zolaikha; Ghavami, Raouf

2016-08-05

Vanillin (VA), vanillic acid (VAI) and syringaldehyde (SIA) are important food additives as flavor enhancers. The current study for the first time is devote to the application of partial least square (PLS-1), partial robust M-regression (PRM) and feed forward neural networks (FFNNs) as linear and nonlinear chemometric methods for the simultaneous detection of binary and ternary mixtures of VA, VAI and SIA using data extracted directly from UV-spectra with overlapped peaks of individual analytes. Under the optimum experimental conditions, for each compound a linear calibration was obtained in the concentration range of 0.61-20.99 [LOD=0.12], 0.67-23.19 [LOD=0.13] and 0.73-25.12 [LOD=0.15] μgmL(-1) for VA, VAI and SIA, respectively. Four calibration sets of standard samples were designed by combination of a full and fractional factorial designs with the use of the seven and three levels for each factor for binary and ternary mixtures, respectively. The results of this study reveal that both the methods of PLS-1 and PRM are similar in terms of predict ability each binary mixtures. The resolution of ternary mixture has been accomplished by FFNNs. Multivariate curve resolution-alternating least squares (MCR-ALS) was applied for the description of spectra from the acid-base titration systems each individual compound, i.e. the resolution of the complex overlapping spectra as well as to interpret the extracted spectral and concentration profiles of any pure chemical species identified. Evolving factor analysis (EFA) and singular value decomposition (SVD) were used to distinguish the number of chemical species. Subsequently, their corresponding dissociation constants were derived. Finally, FFNNs has been used to detection active compounds in real and spiked water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigating the discrimination potential of linear and nonlinear spectral multivariate calibrations for analysis of phenolic compounds in their binary and ternary mixtures and calculation pKa values

NASA Astrophysics Data System (ADS)

Rasouli, Zolaikha; Ghavami, Raouf

2016-08-01

Vanillin (VA), vanillic acid (VAI) and syringaldehyde (SIA) are important food additives as flavor enhancers. The current study for the first time is devote to the application of partial least square (PLS-1), partial robust M-regression (PRM) and feed forward neural networks (FFNNs) as linear and nonlinear chemometric methods for the simultaneous detection of binary and ternary mixtures of VA, VAI and SIA using data extracted directly from UV-spectra with overlapped peaks of individual analytes. Under the optimum experimental conditions, for each compound a linear calibration was obtained in the concentration range of 0.61-20.99 [LOD = 0.12], 0.67-23.19 [LOD = 0.13] and 0.73-25.12 [LOD = 0.15] μg mL- 1 for VA, VAI and SIA, respectively. Four calibration sets of standard samples were designed by combination of a full and fractional factorial designs with the use of the seven and three levels for each factor for binary and ternary mixtures, respectively. The results of this study reveal that both the methods of PLS-1 and PRM are similar in terms of predict ability each binary mixtures. The resolution of ternary mixture has been accomplished by FFNNs. Multivariate curve resolution-alternating least squares (MCR-ALS) was applied for the description of spectra from the acid-base titration systems each individual compound, i.e. the resolution of the complex overlapping spectra as well as to interpret the extracted spectral and concentration profiles of any pure chemical species identified. Evolving factor analysis (EFA) and singular value decomposition (SVD) were used to distinguish the number of chemical species. Subsequently, their corresponding dissociation constants were derived. Finally, FFNNs has been used to detection active compounds in real and spiked water samples.

A minimal mathematical model combining several regulatory cycles from the budding yeast cell cycle.

PubMed

Sriram, K; Bernot, G; Képès, F

2007-11-01

A novel topology of regulatory networks abstracted from the budding yeast cell cycle is studied by constructing a simple nonlinear model. A ternary positive feedback loop with only positive regulations is constructed with elements that activates the subsequent element in a clockwise fashion. A ternary negative feedback loop with only negative regulations is constructed with the elements that inhibit the subsequent element in an anticlockwise fashion. Positive feedback loop exhibits bistability, whereas the negative feedback loop exhibits limit cycle oscillations. The novelty of the topology is that the corresponding elements in these two homogeneous feedback loops are linked by the binary positive feedback loops with only positive regulations. This results in the emergence of mixed feedback loops in the network that displays complex behaviour like the coexistence of multiple steady states, relaxation oscillations and chaos. Importantly, the arrangement of the feedback loops brings in the notion of checkpoint in the model. The model also exhibits domino-like behaviour, where the limit cycle oscillations take place in a stepwise fashion. As the aforementioned topology is abstracted from the budding yeast cell cycle, the events that govern the cell cycle are considered for the present study. In budding yeast, the sequential activation of the transcription factors, cyclins and their inhibitors form mixed feedback loops. The transcription factors that involve in the positive regulation in a clockwise orientation generates ternary positive feedback loop, while the cyclins and their inhibitors that involve in the negative regulation in an anticlockwise orientation generates ternary negative feedback loop. The mutual regulation between the corresponding elements in the transcription factors and the cyclins and their inhibitors generates binary positive feedback loops. The bifurcation diagram constructed for the whole system can be related to the different events of the cell cycle in terms of dynamical system theory. The checkpoint mechanism that plays an important role in different phases of the cell cycle are accounted for by silencing appropriate feedback loops in the model.

Preparation and luminescent properties of the novel polymer-rare earth complexes composed of Poly(ethylene-co-acrylic acid) and Europium ions

NASA Astrophysics Data System (ADS)

Wu, Yuewen; Hao, Haixia; Wu, Qingyao; Gao, Zihan; Xie, Hongde

2018-06-01

A series of novel polymer-rare earth complexes with Eu3+ ions have been synthesized and investigated successfully, including the binary complexes containing the single ligand poly(ethylene-co-acrylic acid) (EAA) and the ternary complexes using 1,10-phenanthroline (phen), dibenzoylmethane (DBM) or thenoyltrifluoroacetone (TTA) as the second ligand. Their structures have been characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis and X-ray diffraction (XRD), which confirm that both EAA and small molecules participate in the coordination reaction with rare earth ions, and they can disperse homogeneously in the polymer matrixes. Both ultraviolet-visible (UV-vis) absorption and photoluminescence tests for the complexes have been recorded. The relationship between fluorescence intensity of polymer-rare earth complexes and the quantity of ligand EAA has been studied and discussed. The films casted from the complexes solution can emit strong characteristic red light under UV light excitation. All these results suggest that the complexes possess potential application as luminescent materials.

Multicomponent ternary cocrystals of the sulfonamide group with pyridine-amides and lactams.

PubMed

Bolla, Geetha; Nangia, Ashwini

2015-11-04

SMBA was selected as a bifunctional sulfa drug to design ternary cocrystals with pyridine amides and lactam coformers. Supramolecular assembly of five ternary cocrystals of p-sulfonamide benzoic acid with nicotinamide and 2-pyridone is demonstrated and reproducible heterosynthons are identified for crystal engineering.

Role of electron concentration in softening and hardening of ternary molybdenum alloys

NASA Technical Reports Server (NTRS)

Stephens, J. R.; Witzke, W. R.

1975-01-01

Effects of various combinations of hafnium, tantalum, rhenium, osmium, iridium, and platinum in ternary molybdenum alloys on alloy softening and hardening were determined. Hardness tests were conducted at four test temperatures over the temperature range 77 to 411 K. Results showed that hardness data for ternary molybdenum alloys could be correlated with anticipated results from binary data based upon expressions involving the number of s and d electrons contributed by the solute elements. The correlation indicated that electron concentration plays a dominant role in controlling the hardness of ternary molybdenum alloys.

MnO2 Nanorods Intercalating Graphene Oxide/Polyaniline Ternary Composites for Robust High-Performance Supercapacitors

PubMed Central

Han, Guangqiang; Liu, Yun; Zhang, Lingling; Kan, Erjun; Zhang, Shaopeng; Tang, Jian; Tang, Weihua

2014-01-01

New ternary composites of MnO2 nanorods, polyaniline (PANI) and graphene oxide (GO) have been prepared by a two-step process. The 100 nm-long MnO2 nanorods with a diameter ~20 nm are conformably coated with PANI layers and fastened between GO layers. The MnO2 nanorods incorporated ternary composites electrode exhibits significantly increased specific capacitance than PANI/GO binary composite in supercapacitors. The ternary composite with 70% MnO2 exhibits a highest specific capacitance reaching 512 F/g and outstanding cycling performance, with ~97% capacitance retained over 5000 cycles. The ternary composite approach offers an effective solution to enhance the device performance of metal-oxide based supercapacitors for long cycling applications. PMID:24769835

Ternary Solar Cells Based on Two Small Molecule Donors with Same Conjugated Backbone: The Role of Good Miscibility and Hole Relay Process.

PubMed

Xiao, Liangang; Liang, Tianxiang; Gao, Ke; Lai, Tianqi; Chen, Xuebin; Liu, Feng; Russell, Thomas P; Huang, Fei; Peng, Xiaobin; Cao, Yong

2017-09-06

Ternary organic solar cells (OSCs) are very attractive for further enhancing the power conversion efficiencies (PCEs) of binary ones but still with a single active layer. However, improving the PCEs is still challenging because a ternary cell with one more component is more complicated on phase separation behavior. If the two donors or two acceptors have similar chemical structures, good miscibility can be expected to reduce the try-and-error work. Herein, we report ternary devices based on two small molecule donors with the same backbone but different substituents. Whereas both binary devices show PCEs about 9%, the PCE of the ternary cells is enhanced to 10.17% with improved fill factor and short-circuit current values and external quantum efficiencies almost in the whole absorption wavelength region from 440 to 850 nm. The same backbone enables the donors miscible at molecular level, and the donor with a higher HOMO level plays hole relay process to facilitate the charge transportation in the ternary devices. Since side-chain engineering has been well performed to tune the active materials' energy levels in OSCs, our results suggest that their ternary systems are promising for further improving the binary cells' performance although their absorptions are not complementary.

Catalysis by Methylamine Dehydrogenase and Electron Transfer to Amicyanin and Cytochrome C(551I) from Paracoccus Denitrificans.

NASA Astrophysics Data System (ADS)

Brooks, Harold Burns

1995-01-01

The quinoprotein methylamine dehydrogenase (MADH), a type I copper protein, amicyanin, and cytochrome c _{55li} form a physiologic ternary complex (Chen et al. (1994) Science 264, 86-90) in which electrons are transferred from tryptophan tryptophylquinone to copper to heme. The reduction of MADH by rm H_3- and rm D_3 -methylamine, the reoxidation of MADH by amicyanin, and the reduction of cytochrome c_{55li } by reduced amicyanin in the presence of MADH have been studied by stopped-flow spectroscopy. When rm CD_3NH_2 was used as a substrate for MADH a deuterium kinetic isotope effect of 17.2 was measured for the hydrogen abstraction step. The maximum deuterium kinetic isotope effect that was measured in steady-state kinetic experiments was 3.0. The temperature dependencies of the rate constants for the reaction of methylamine with MADH were also determined. An iminosemiquinone intermediate for the oxidation of substrate-reduced MADH by amicyanin was detected using stopped-flow spectroscopy, and the presence of the substrate derived nitrogen was confirmed by electron spin echo envelope modulation (ESEEM) spectroscopy. Marcus theory, which was used to analyze the electron transfer reaction between the dithionite-generated redox forms of MADH and amicyanin, gave values of 218 kJ rm mol^{ -1} (2.3 eV) for the reorganizational energy (lambda ) and 11.6 rm cm^{-1} for the coupling rm (H_{AB}). In contrast, the oxidation of substrate-reduced MADH by amicyanin was a gated electron transfer reaction with values for DeltaH* of 76 kJ rm mol^ {-1} and DeltaS* of -41 J rm mol^{ -1} ^circ K^ {-1}. These studies are consistent with the formation of transient unstable intermediates preceeding electron transfer between MADH and amicyanin. Preliminary investigations of the ternary complex of MADH, amicyanin, and cytochrome c_{55li } suggest two distinct cytochrome c _{55li} binding sites on amicyanin. This conclusion is supported by the biphasic nature of the stopped -flow trace, the inhibition of the rm k^ {fast}_{obs} by MADH, and the ionic strength dependence of the two phases. The slow phase had a rate of 3.1 rm s^ {-1} which is consistent with electron transfer between amicyanin and cytochrome c_ {55li} within the ternary complex. The fast phase does not exhibit saturation behavior, must have an electron transfer rate greater than 1000 rm s^{-1}, and likely involves a complex of amicyanin and cytochrome c_{55li } near the hydrophobic patch of amicyanin.

Cloning and characterization of GETS-1, a goldfish Ets family member that functions as a transcriptional repressor in muscle.

PubMed

Goldman, D; Sapru, M K; Stewart, S; Plotkin, J; Libermann, T A; Wasylyk, B; Guan, K

1998-10-15

An Ets transcription factor family member, GETS-1, was cloned from a goldfish retina cDNA library. GETS-1 contains a conserved Ets DNA-binding domain at its N-terminus and is most similar to ternary complex factor (TCF) serum-response-factor protein-1a (SAP-1a). GETS-1 is expressed in many tissues, but is enriched in retina and brain. As with the TCFs SAP-1a and ets-related protein (ERP), overexpression of the GETS-1 promoter suppresses nicotinic acetylcholine receptor epsilon-subunit gene expression in cultured muscle cells. A consensus Ets binding site sequence in the promoter of the epsilon-subunit gene is required for GETS-1-mediated repression. GETS-1 repressor activity is abrogated by overexpression of an activated Ras/mitogen-activated protein kinase (MAP kinase) or by mutation of Ser-405, a MAP kinase phosphorylation site in GETS-1. Fusion proteins created between GETS-1 and the Gal4 DNA-binding domain show that, like other TCFs, GETS-1 contains a C-terminal activation domain that is activated by a Ras/MAP kinase signalling cascade. Interestingly, mutation of Ser-405 located within this activation domain abrogated transcriptional activation of the fusion protein.

Dynamic Regulation of Tgf-B Signaling by Tif1γ: A Computational Approach

PubMed Central

Andrieux, Geoffroy; Fattet, Laurent; Le Borgne, Michel; Rimokh, Ruth; Théret, Nathalie

2012-01-01

TIF1γ (Transcriptional Intermediary Factor 1 γ) has been implicated in Smad-dependent signaling by Transforming Growth Factor beta (TGF-β). Paradoxically, TIF1γ functions both as a transcriptional repressor or as an alternative transcription factor that promotes TGF-β signaling. Using ordinary differential-equation models, we have investigated the effect of TIF1γ on the dynamics of TGF-β signaling. An integrative model that includes the formation of transient TIF1γ-Smad2-Smad4 ternary complexes is the only one that can account for TGF-β signaling compatible with the different observations reported for TIF1γ. In addition, our model predicts that varying TIF1γ/Smad4 ratios play a critical role in the modulation of the transcriptional signal induced by TGF-β, especially for short stimulation times that mediate higher threshold responses. Chromatin immunoprecipitation analyses and quantification of the expression of TGF-β target genes as a function TIF1γ/Smad4 ratios fully validate this hypothesis. Our integrative model, which successfully unifies the seemingly opposite roles of TIF1γ, also reveals how changing TIF1γ/Smad4 ratios affect the cellular response to stimulation by TGF-β, accounting for a highly graded determination of cell fate. PMID:22461896

Quantum dot ternary-valued full-adder: Logic synthesis by a multiobjective design optimization based on a genetic algorithm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klymenko, M. V.; Remacle, F., E-mail: fremacle@ulg.ac.be

2014-10-28

A methodology is proposed for designing a low-energy consuming ternary-valued full adder based on a quantum dot (QD) electrostatically coupled with a single electron transistor operating as a charge sensor. The methodology is based on design optimization: the values of the physical parameters of the system required for implementing the logic operations are optimized using a multiobjective genetic algorithm. The searching space is determined by elements of the capacitance matrix describing the electrostatic couplings in the entire device. The objective functions are defined as the maximal absolute error over actual device logic outputs relative to the ideal truth tables formore » the sum and the carry-out in base 3. The logic units are implemented on the same device: a single dual-gate quantum dot and a charge sensor. Their physical parameters are optimized to compute either the sum or the carry out outputs and are compatible with current experimental capabilities. The outputs are encoded in the value of the electric current passing through the charge sensor, while the logic inputs are supplied by the voltage levels on the two gate electrodes attached to the QD. The complex logic ternary operations are directly implemented on an extremely simple device, characterized by small sizes and low-energy consumption compared to devices based on switching single-electron transistors. The design methodology is general and provides a rational approach for realizing non-switching logic operations on QD devices.« less

Extensive Evaluation of the Conductor-like Screening Model for Real Solvents Method in Predicting Liquid-Liquid Equilibria in Ternary Systems of Ionic Liquids with Molecular Compounds.

PubMed

Paduszyński, Kamil

2018-04-12

A conductor-like screening model for real solvents (COSMO-RS) is nowadays one of the most popular and commonly applied tools for the estimation of thermodynamic properties of complex fluids. The goal of this work is to provide a comprehensive review and analysis of the performance of this approach in calculating liquid-liquid equilibrium (LLE) phase diagrams in ternary systems composed of ionic liquid and two molecular compounds belonging to diverse families of chemicals (alkanes, aromatics, S/N-compounds, alcohols, ketones, ethers, carboxylic acid, esters, and water). The predictions are presented for extensive experimental database, including 930 LLE data sets and more than 9000 data points (LLE tie lines) reported for 779 unique ternary mixtures. An impact of the type of molecular binary subsystem on the accuracy of predictions is demonstrated and discussed on the basis of representative examples. The model's capability of capturing qualitative trends in the LLE distribution ratio and selectivity is also checked for a number of structural effects. Comparative analysis of two levels of quantum chemical theory (BP-TZVP-COSMO vs BP-TZVPD-FINE) for the input molecular data for COSMO-RS is presented. Finally, some general recommendations for the applicability of the model are indicated based on the analysis of the global performance as well as on the results obtained for systems relevant from the point of view of important separation problems.

Controlling the physics and chemistry of binary and ternary praseodymium and cerium oxide systems.

PubMed

Niu, Gang; Zoellner, Marvin Hartwig; Schroeder, Thomas; Schaefer, Andreas; Jhang, Jin-Hao; Zielasek, Volkmar; Bäumer, Marcus; Wilkens, Henrik; Wollschläger, Joachim; Olbrich, Reinhard; Lammers, Christian; Reichling, Michael

2015-10-14

Rare earth praseodymium and cerium oxides have attracted intense research interest in the last few decades, due to their intriguing chemical and physical characteristics. An understanding of the correlation between structure and properties, in particular the surface chemistry, is urgently required for their application in microelectronics, catalysis, optics and other fields. Such an understanding is, however, hampered by the complexity of rare earth oxide materials and experimental methods for their characterisation. Here, we report recent progress in studying high-quality, single crystalline, praseodymium and cerium oxide films as well as ternary alloys grown on Si(111) substrates. Using these well-defined systems and based on a systematic multi-technique surface science approach, the corresponding physical and chemical properties, such as the surface structure, the surface morphology, the bulk-surface interaction and the oxygen storage/release capability, are explored in detail. We show that specifically the crystalline structure and the oxygen stoichiometry of the oxide thin films can be well controlled by the film preparation method. This work leads to a comprehensive understanding of the properties of rare earth oxides and highlights the applications of these versatile materials. Furthermore, methanol adsorption studies are performed on binary and ternary rare earth oxide thin films, demonstrating the feasibility of employing such systems for model catalytic studies. Specifically for ceria systems, we find considerable stability against normal environmental conditions so that they can be considered as a "materials bridge" between surface science models and real catalysts.

Structural and viscoelastic characterization of ternary mixtures of sunflower oil, saturated monoglycerides and aqueous phases containing different bases.

PubMed

Valoppi, Fabio; Calligaris, Sonia; Barba, Luisa; Nicoli, Maria Cristina

2015-08-01

The structure at different length scales and the viscoelastic properties of ternary mixtures composed of saturated monoglycerides, sunflower oil and aqueous solutions of weak bases (KHCO 3 , NaHCO 3 , and NH 4 HCO 3 ) or strong bases (NaOH and KOH) were investigated. The characteristics of ternary mixtures were studied systematically by using polarized light microscopy, differential scanning calorimetry (DSC), synchrotron X-ray diffraction (XRD) and rheological analysis. Results showed that the base type and concentration greatly affected the structure of the mixtures. The use of strong bases allowed gelled systems to be obtained only at low concentrations (<10mM). On the contrary, the presence of weak bases induced gelling at all concentrations considered (from 1 to 1000mM). The increase of base concentration led to a reduction of the mean droplet diameter and melting temperature. At the same time, the viscoelastic characteristics as a function of base concentration followed a more complex behavior: G' and G″ progressively decreased as the salt concentration increased in a concentration range from 1 to 100mM, while the rheological parameters increased when salt concentration increased from 100 to 1000mM. The structural and viscoelastic behavior of systems prepared with different salts were commonly independent of the cation present in the medium. Results highlight that it is possible to tailor the structure of these gels by using specific bases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bottom-up and Top-down Approaches to Explore Sodium Dodecyl Sulfate and Soluplus on the Crystallization Inhibition and Dissolution of Felodipine Extrudates.

PubMed

Chen, Jiali; Chen, Yuqi; Huang, Wencong; Wang, Hanning; Du, Yang; Xiong, Subin

2018-05-05

The objectives of this study were to explore sodium dodecyl sulfate (SDS) and Soluplus on the crystallization inhibition and dissolution of felodipine (FLDP) extrudates by bottom-up and top-down approaches. FLDP extrudates with Soluplus and/or SDS were prepared by hot melt extrusion (HME), and characterized by PLM, DSC and FT-IR. Results indicated that Soluplus inhibited FLDP crystallization and the whole amorphous solid dispersions (ASDs) were binary FLDP-Soluplus (1:3) and ternary FLDP-Soluplus-SDS(1:2:0.15∼0.3 and 1:3:0.2∼0.4) extrudates. Internal SDS (5%-10%) decreased Tgs of FLDP-Soluplus-SDS ternary ASDs without presenting molecular interactions with FLDP or Soluplus. The enhanced dissolution rate of binary or ternary Soluplus-rich ASDs in the non-sink condition of 0.05%SDS was achieved. Bottom-up approach indicated that Soluplus was a much stronger crystal inhibitor to the supersaturated FLDP in solutions than SDS. Top-down approach demonstrated that SDS enhanced the dissolution of Soluplus-rich ASDs via wettability and complexation with Soluplus to accelerate the medium uptake and erosion kinetics of extrudates, but induced FLDP recrystallization and resulted in incomplete dissolution of FLDP-rich extrudates. In conclusion, top-down approach is a promising strategy to explore the mechanisms of ASDs' dissolution, and small amount of SDS enhances the dissolution rate of polymer-rich ASDs in the non-sink condition. Copyright © 2018. Published by Elsevier Inc.

Experimental evidence for ternary colloid-facilitated transport of Th(IV) with hematite (α-Fe2O3) colloids and Suwannee River fulvic acid.

PubMed

Emerson, Hilary P; Hickok, Katherine A; Powell, Brian A

2016-12-01

Previous field experiments have suggested colloid-facilitated transport via inorganic and organic colloids as the primary mechanism of enhanced actinide transport in the subsurface at former nuclear weapons facilities. In this work, research was guided by the hypothesis that humic substances can enhance tetravalent actinide (An(IV)) migration by coating and mobilizing natural colloids in environmental systems and increasing An(IV) sorption to colloids. This mechanism is expected to occur under relatively acidic conditions where organic matter can sorb and coat colloid surfaces and facilitate formation of ternary colloid-ligand-actinide complexes. The objective of this work was to examine Th transport through packed columns in the presence of hematite colloids and/or Suwannee River fulvic acid (SRFA). In the presence of SRFA, with or without hematite colloids, significant transport (>60% recovery within the effluent) of thorium occurred through quartz columns. It is notable that the SRFA contributed to increased transport of both Th and hematite colloids, while insignificant transport occurred in the absence of fulvic acid. Further, in the presence of a natural sandy sediment (as opposed to pure quartz), transport is negligible in the presence of SRFA due to interactions with natural, clay-sized sediment coatings. Moreover, this data shows that the transport of Th through quartz columns is enhanced in ternary Th-colloid-SRFA and binary Th-SRFA systems as compared to a system containing only Th. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and thermal characterization of new ternary chelates of piroxicam and tenoxicam with glycine and DL-phenylalanine and some transition metals.

PubMed

Zayed, M A; El-Dien, F A Nour; Mohamed, Gehad G; El-Gamel, Nadia E A

2006-05-01

The ternary chelates of piroxicam (Pir) and tenoxicam (Ten) with Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) in the presence of various amino acids such as glycine (Gly) or dl-phenylalanine (PhA) were prepared and characterized with different physicochemical methods. IR spectra confirm that Pir and Ten behave as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its deprotonated carboxylic group. In addition, PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its deprotonated carboxylic and amino groups. The solid reflectance spectra and magnetic moment measurements confirm that all the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. Thermal behaviour of the complexes is extensively studied using TG and DTA techniques. TG results show that water molecules (hydrated and coordinated) and anions are removed in the first and second steps while Gly, PhA, Pir and Ten are decomposed in the next and subsequent steps. The pyrolyses of the chelates into different gases are observed in the DTA curves as exo- or endothermic peaks. Also, phase transition states are observed in some chelates. Different thermodynamic parameters are calculated using Coats-Redfern method and the results are interpreted.

Synthesis and thermal characterization of new ternary chelates of piroxicam and tenoxicam with glycine and DL-phenylalanine and some transition metals

NASA Astrophysics Data System (ADS)

Zayed, M. A.; El-Dien, F. A. Nour; Mohamed, Gehad G.; El-Gamel, Nadia E. A.

2006-05-01

The ternary chelates of piroxicam (Pir) and tenoxicam (Ten) with Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) in the presence of various amino acids such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized with different physicochemical methods. IR spectra confirm that Pir and Ten behave as a neutral bidentate ligand coordinated to the metal ions via the pyridine- N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its deprotonated carboxylic group. In addition, PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its deprotonated carboxylic and amino groups. The solid reflectance spectra and magnetic moment measurements confirm that all the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. Thermal behaviour of the complexes is extensively studied using TG and DTA techniques. TG results show that water molecules (hydrated and coordinated) and anions are removed in the first and second steps while Gly, PhA, Pir and Ten are decomposed in the next and subsequent steps. The pyrolyses of the chelates into different gases are observed in the DTA curves as exo- or endothermic peaks. Also, phase transition states are observed in some chelates. Different thermodynamic parameters are calculated using Coats-Redfern method and the results are interpreted.

Evaluation of the efficiency of continuous wavelet transform as processing and preprocessing algorithm for resolution of overlapped signals in univariate and multivariate regression analyses; an application to ternary and quaternary mixtures

NASA Astrophysics Data System (ADS)

Hegazy, Maha A.; Lotfy, Hayam M.; Mowaka, Shereen; Mohamed, Ekram Hany

2016-07-01

Wavelets have been adapted for a vast number of signal-processing applications due to the amount of information that can be extracted from a signal. In this work, a comparative study on the efficiency of continuous wavelet transform (CWT) as a signal processing tool in univariate regression and a pre-processing tool in multivariate analysis using partial least square (CWT-PLS) was conducted. These were applied to complex spectral signals of ternary and quaternary mixtures. CWT-PLS method succeeded in the simultaneous determination of a quaternary mixture of drotaverine (DRO), caffeine (CAF), paracetamol (PAR) and p-aminophenol (PAP, the major impurity of paracetamol). While, the univariate CWT failed to simultaneously determine the quaternary mixture components and was able to determine only PAR and PAP, the ternary mixtures of DRO, CAF, and PAR and CAF, PAR, and PAP. During the calculations of CWT, different wavelet families were tested. The univariate CWT method was validated according to the ICH guidelines. While for the development of the CWT-PLS model a calibration set was prepared by means of an orthogonal experimental design and their absorption spectra were recorded and processed by CWT. The CWT-PLS model was constructed by regression between the wavelet coefficients and concentration matrices and validation was performed by both cross validation and external validation sets. Both methods were successfully applied for determination of the studied drugs in pharmaceutical formulations.

Real-time single-molecule electronic DNA sequencing by synthesis using polymer-tagged nucleotides on a nanopore array

PubMed Central

Fuller, Carl W.; Kumar, Shiv; Porel, Mintu; Chien, Minchen; Bibillo, Arek; Stranges, P. Benjamin; Dorwart, Michael; Tao, Chuanjuan; Li, Zengmin; Guo, Wenjing; Shi, Shundi; Korenblum, Daniel; Trans, Andrew; Aguirre, Anne; Liu, Edward; Harada, Eric T.; Pollard, James; Bhat, Ashwini; Cech, Cynthia; Yang, Alexander; Arnold, Cleoma; Palla, Mirkó; Hovis, Jennifer; Chen, Roger; Morozova, Irina; Kalachikov, Sergey; Russo, James J.; Kasianowicz, John J.; Davis, Randy; Roever, Stefan; Church, George M.; Ju, Jingyue

2016-01-01

DNA sequencing by synthesis (SBS) offers a robust platform to decipher nucleic acid sequences. Recently, we reported a single-molecule nanopore-based SBS strategy that accurately distinguishes four bases by electronically detecting and differentiating four different polymer tags attached to the 5′-phosphate of the nucleotides during their incorporation into a growing DNA strand catalyzed by DNA polymerase. Further developing this approach, we report here the use of nucleotides tagged at the terminal phosphate with oligonucleotide-based polymers to perform nanopore SBS on an α-hemolysin nanopore array platform. We designed and synthesized several polymer-tagged nucleotides using tags that produce different electrical current blockade levels and verified they are active substrates for DNA polymerase. A highly processive DNA polymerase was conjugated to the nanopore, and the conjugates were complexed with primer/template DNA and inserted into lipid bilayers over individually addressable electrodes of the nanopore chip. When an incoming complementary-tagged nucleotide forms a tight ternary complex with the primer/template and polymerase, the tag enters the pore, and the current blockade level is measured. The levels displayed by the four nucleotides tagged with four different polymers captured in the nanopore in such ternary complexes were clearly distinguishable and sequence-specific, enabling continuous sequence determination during the polymerase reaction. Thus, real-time single-molecule electronic DNA sequencing data with single-base resolution were obtained. The use of these polymer-tagged nucleotides, combined with polymerase tethering to nanopores and multiplexed nanopore sensors, should lead to new high-throughput sequencing methods. PMID:27091962

The DNA binding site specificity and antiproliferative property of ternary Pt(II) and Zn(II) complexes of phenanthroline and N,N'-ethylenediaminediacetic acid.

PubMed

Nakamura, Yusuke; Taruno, Yoko; Sugimoto, Masashi; Kitamura, Yusuke; Seng, Hoi Ling; Kong, Siew Ming; Ng, Chew Hee; Chikira, Makoto

2013-03-14

The binding site specificity of the ternary complexes, [M(II)(phen)(edda)] (M(II) = Pt(2+) and Zn(2+); phen = 1,10-phenanthroline; edda = N,N'-ethylenediaminediacetic acid), for the self-complementary oligonucleotides (ODNs), ds(C(1)G(2)C(3)G(4)A(5)A(6)T(7)T(8)C(9)G(10)C(11)G(12))(2) (ODN1) and ds(C(1)G(2)C(3)G(4)T(5)A(6)T(7)A(8)C(9)G(10)C(11)G(12))(2) (ODN2), was studied by NMR measurements. The results indicated that [Pt(ii)(phen)(edda)] was partially intercalated between C(3)/G(10) and G(4)/C(9) base pairs of ODN1 and ODN2 in the major grooves, whereas [Zn(II)(phen)(edda)] was bound specifically to the TATA region of ODN2 in the minor groove and to the terminal G(2)/C(11) base pair of ODN1 in the major groove. The preference for the TATA sequence over the AATT sequence in the binding of [Zn(phen)(edda)] was attributed to the wider minor groove width of the TATA sequence. The bindings of the complexes to ct-DNA were also studied by UV, CD, and fluorescence spectroscopy. Additionally, the antiproliferative property of [Pt(II)(phen)(edda)] towards MCF7 breast cancer cells and normal MCF10-A cells was compared with that of [Zn(II)(phen)(edda)].

Hydration of the sulfuric acid-methylamine complex and implications for aerosol formation.

PubMed

Bustos, Danielle J; Temelso, Berhane; Shields, George C

2014-09-04

The binary H2SO4-H2O nucleation is one of the most important pathways by which aerosols form in the atmosphere, and the presence of ternary species like amines increases aerosol formation rates. In this study, we focus on the hydration of a ternary system of sulfuric acid (H2SO4), methylamine (NH2CH3), and up to six waters to evaluate its implications for aerosol formation. By combining molecular dynamics (MD) sampling with high-level ab initio calculations, we determine the thermodynamics of forming H2SO4(NH2CH3)(H2O)n, where n = 0-6. Because it is a strong acid-base system, H2SO4-NH2CH3 quickly forms a tightly bound HSO4(-)-NH3CH3(+) complex that condenses water more readily than H2SO4 alone. The electronic binding energy of H2SO4-NH2CH3 is -21.8 kcal mol(-1) compared with -16.8 kcal mol(-1) for H2SO4-NH3 and -12.8 kcal mol(-1) for H2SO4-H2O. Adding one to two water molecules to the H2SO4-NH2CH3 complex is more favorable than adding to H2SO4 alone, yet there is no systematic difference for n ≥ 3. However, the average number of water molecules around H2SO4-NH2CH3 is consistently higher than that of H2SO4, and it is fairly independent of temperature and relative humidity.

Multiple ligand-binding modes in bacterial R67 dihydrofolate reductase

NASA Astrophysics Data System (ADS)

Alonso, Hernán; Gillies, Malcolm B.; Cummins, Peter L.; Bliznyuk, Andrey A.; Gready, Jill E.

2005-03-01

R67 dihydrofolate reductase (DHFR), a bacterial plasmid-encoded enzyme associated with resistance to the drug trimethoprim, shows neither sequence nor structural homology with the chromosomal DHFR. It presents a highly symmetrical toroidal structure, where four identical monomers contribute to the unique central active-site pore. Two reactants (dihydrofolate, DHF), two cofactors (NADPH) or one of each (R67•DHF•NADPH) can be found simultaneously within the active site, the last one being the reactive ternary complex. As the positioning of the ligands has proven elusive to empirical determination, we addressed the problem from a theoretical perspective. Several potential structures of the ternary complex were generated using the docking programs AutoDock and FlexX. The variability among the final poses, many of which conformed to experimental data, prompted us to perform a comparative scoring analysis and molecular dynamics simulations to assess the stability of the complexes. Analysis of ligand-ligand and ligand-protein interactions along the 4 ns trajectories of eight different structures allowed us to identify important inter-ligand contacts and key protein residues. Our results, combined with published empirical data, clearly suggest that multipe binding modes of the ligands are possible within R67 DHFR. While the pterin ring of DHF and the nicotinamide ring of NADPH assume a stacked endo-conformation at the centre of the pore, probably assisted by V66, Q67 and I68, the tails of the molecules extend towards opposite ends of the cavity, adopting multiple configurations in a solvent rich-environment where hydrogen-bond interactions with K32 and Y69 may play important roles.

Ternary polyplex micelles with PEG shells and intermediate barrier to complexed DNA cores for efficient systemic gene delivery.

PubMed

Li, Junjie; Chen, Qixian; Zha, Zengshi; Li, Hui; Toh, Kazuko; Dirisala, Anjaneyulu; Matsumoto, Yu; Osada, Kensuke; Kataoka, Kazunori; Ge, Zhishen

2015-07-10

Simultaneous achievement of prolonged retention in blood circulation and efficient gene transfection activity in target tissues has always been a major challenge hindering in vivo applications of nonviral gene vectors via systemic administration. Herein, we constructed novel rod-shaped ternary polyplex micelles (TPMs) via complexation between the mixed block copolymers of poly(ethylene glycol)-b-poly{N'-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} (PEG-b-PAsp(DET)) and poly(N-isopropylacrylamide)-b-PAsp(DET) (PNIPAM-b-PAsp(DET)) and plasmid DNA (pDNA) at room temperature, exhibiting distinct temperature-responsive formation of a hydrophobic intermediate layer between PEG shells and pDNA cores through facile temperature increase from room temperature to body temperature (~37 °C). As compared with binary polyplex micelles of PEG-b-PAsp(DET) (BPMs), TPMs were confirmed to condense pDNA into a more compact structure, which achieved enhanced tolerability to nuclease digestion and strong counter polyanion exchange. In vitro gene transfection results demonstrated TPMs exhibiting enhanced gene transfection efficiency due to efficient cellular uptake and endosomal escape. Moreover, in vivo performance evaluation after intravenous injection confirmed that TPMs achieved significantly prolonged blood circulation, high tumor accumulation, and promoted gene expression in tumor tissue. Moreover, TPMs loading therapeutic pDNA encoding an anti-angiogenic protein remarkably suppressed tumor growth following intravenous injection into H22 tumor-bearing mice. These results suggest TPMs with PEG shells and facilely engineered intermediate barrier to inner complexed pDNA have great potentials as systemic nonviral gene vectors for cancer gene therapy. Copyright © 2015 Elsevier B.V. All rights reserved.

Efficient Vacuum-Deposited Ternary Organic Solar Cells with Broad Absorption, Energy Transfer, and Enhanced Hole Mobility.

PubMed

Shim, Hyun-Sub; Moon, Chang-Ki; Kim, Jihun; Wang, Chun-Kai; Sim, Bomi; Lin, Francis; Wong, Ken-Tsung; Seo, Yongsok; Kim, Jang-Joo

2016-01-20

The use of multiple donors in an active layer is an effective way to boost the efficiency of organic solar cells by broadening their absorption window. Here, we report an efficient vacuum-deposited ternary organic photovoltaic (OPV) using two donors, 2-((2-(5-(4-(diphenylamino)phenyl)thieno[3,2-b]thiophen-2-yl)thiazol-5-yl)methylene)malononitrile (DTTz) for visible absorption and 2-((7-(5-(dip-tolylamino)thiophen-2-yl)benzo[c]-[1,2,5]thiadiazol-4-yl)methylene)malononitrile (DTDCTB) for near-infrared absorption, codeposited with C70 in the ternary layer. The ternary device achieved a power conversion efficiency of 8.02%, which is 23% higher than that of binary OPVs. This enhancement is the result of incorporating two donors with complementary absorption covering wavelengths of 350 to 900 nm with higher hole mobility in the ternary layer than that of binary layers consisting of one donor and C70, combined with energy transfer from the donor with lower hole mobility (DTTz) to that with higher mobility (DTDCTB). This structure fulfills all the requirements for efficient ternary OPVs.

Structure, equilibrium and ligand exchange dynamics in the binary and ternary dioxouranium(VI)-ethylenediamine-N,N'-diacetic acid-fluoride system: A potentiometric, NMR and X-ray crystallographic study.

PubMed

Palladino, Giuseppe; Szabó, Zoltán; Fischer, Andreas; Grenthe, Ingmar

2006-11-21

The structure, thermodynamics and kinetics of the binary and ternary uranium(VI)-ethylenediamine-N,N'-diacetate (in the following denoted EDDA) fluoride systems have been studied using potentiometry, 1H, 19F NMR spectroscopy and X-ray diffraction. The UO2(2+)-EDDA system could be studied up to -log[H3O+] = 3.4 where the formation of two binary complexes UO2(EDDA)(aq) and UO2(H3EDDA)3+ were identified, with equilibrium constants logbeta(UO2EDDA) = 11.63 +/- 0.02 and logbeta(UO2H3EDDA3+) = 1.77 +/- 0.04, respectively. In the ternary system the complexes UO2(EDDA)F-, UO2(EDDA)(OH)- and (UO2)2(mu-OH)2(HEDDA)2F2(aq) were identified; the latter through 19F NMR. 1H NMR spectra indicate that the EDDA ligand is chelate bonded in UO2(EDDA)(aq), UO2(EDDA)F- and UO2(EDDA)(OH)- while only one carboxylate group is coordinated in UO2(H3EDDA)3+. The rate and mechanism of the fluoride exchange between UO2(EDDA)F- and free fluoride was studied by 19F NMR spectroscopy. Three reactions contribute to the exchange; (i) site exchange between UO2(EDDA)F- and free fluoride without any net chemical exchange, (ii) replacement of the coordinated fluoride with OH- and (iii) the self dissociation of the coordinated fluoride forming UO2(EDDA)(aq); these reactions seem to follow associative mechanisms. (1)H NMR spectra show that the exchange between the free and chelate bonded EDDA is slow and consists of several steps, protonation/deprotonation and chelate ring opening/ring closure, the mechanism cannot be elucidated from the available data. The structure (UO2)2(EDDA)2(mu-H2EDDA) was determined by single crystal X-ray diffraction and contains two UO2(EDDA) units with tetracoordinated EDDA linked by H2EDDA in the "zwitterion" form, coordinated through a single carboxylate oxygen from each end to the two uranium atoms. The geometry of the complexes indicates that there is no geometric constraint for an associative ligand substitution mechanism.

Cobalamin-Independent Methionine Synthase (MetE): A Face-to-Face Double Barrel that Evolved by Gene Duplication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pejcha, Robert; Ludwig, Martha L.

2010-03-08

Cobalamin-independent methionine synthase (MetE) catalyzes the transfer of a methyl group from methyltetrahydrofolate to L-homocysteine (Hcy) without using an intermediate methyl carrier. Although MetE displays no detectable sequence homology with cobalamin-dependent methionine synthase (MetH), both enzymes require zinc for activation and binding of Hcy. Crystallographic analyses of MetE from T. maritima reveal an unusual dual-barrel structure in which the active site lies between the tops of the two ({beta}{alpha}){sub 8} barrels. The fold of the N-terminal barrel confirms that it has evolved from the C-terminal polypeptide by gene duplication; comparisons of the barrels provide an intriguing example of homologous domainmore » evolution in which binding sites are obliterated. The C-terminal barrel incorporates the zinc ion that binds and activates Hcy. The zinc-binding site in MetE is distinguished from the (Cys){sub 3}Zn site in the related enzymes, MetH and betaine-homocysteine methyltransferase, by its position in the barrel and by the metal ligands, which are histidine, cysteine, glutamate, and cysteine in the resting form of MetE. Hcy associates at the face of the metal opposite glutamate, which moves away from the zinc in the binary E {center_dot} Hcy complex. The folate substrate is not intimately associated with the N-terminal barrel; instead, elements from both barrels contribute binding determinants in a binary complex in which the folate substrate is incorrectly oriented for methyl transfer. Atypical locations of the Hcy and folate sites in the C-terminal barrel presumably permit direct interaction of the substrates in a ternary complex. Structures of the binary substrate complexes imply that rearrangement of folate, perhaps accompanied by domain rearrangement, must occur before formation of a ternary complex that is competent for methyl transfer.« less

Synthesis and properties of ternary mixture of nickel/cobalt/tin oxides for supercapacitors

NASA Astrophysics Data System (ADS)

Ferreira, C. S.; Passos, R. R.; Pocrifka, L. A.

2014-12-01

The present study reports the synthesis and morphological, structural and electrochemical characterization of ternary oxides mixture containing nickel, cobalt and tin. The ternary oxide is synthesized by Pechini method with subsequent deposition onto a titanium substrate in a thin-film form. XRD and EDS analysis confirm the formation of ternary film with amorphous nature. SEM analysis show that cracks on the film favor the gain of the surface area that is an interesting feature for electrochemical capacitors. The ternary film is investigated in KOH electrolyte solution using cyclic voltammetry and charge-discharge study with a specific capacitance of 328 F g-1, and a capacitance retention of 86% over 600 cycles. The values of specific power and specific energy was 345.7 W kg-1 and 18.92 Wh kg-1, respectively.

Compression behavior of quaternary and higher order solid-solution L1(2) trialuminides

NASA Technical Reports Server (NTRS)

Kumar, K. S.; Brown, S. A.

1992-01-01

Results from preliminary studies undertaken to evaluate the existence of single-phase L1(2) solid solutions between pairs of ternary L1(2) trialuminides are presented. Two-kilogram ingots of selected quaternary compositions were cast, homogenized and forged into pancakes; compression specimens were machined from the forgings and tested as a function of temperature. The results are compared against existing data for the ternary alloys. The ternary L1(2) trialuminides Al66Ti25Mn9, Al67Ti25Cr8, and Al22Ti8Fe3 were found to exhibit continuous solubility in one another. The quaternary Cr-Mn composition does not indicate any strength advantage over its ternary counterparts. The continuous replacement of Mn with Fe enhances the strength of the quaternary compound over the ternary Al66Ti25 Mn9.

The nucleotide-free state of heterotrimeric G proteins α-subunit adopts a highly stable conformation.

PubMed

Andhirka, Sai Krishna; Vignesh, Ravichandran; Aradhyam, Gopala Krishna

2017-08-01

Deciphering the mechanism of activation of heterotrimeric G proteins by their cognate receptors continues to be an intriguing area of research. The recently solved crystal structure of the ternary complex captured the receptor-bound α-subunit in an open conformation, without bound nucleotide has improved our understanding of the activation process. Despite these advancements, the mechanism by which the receptor causes GDP release from the α-subunit remains elusive. To elucidate the mechanism of activation, we studied guanine nucleotide-induced structural stability of the α-subunit (in response to thermal/chaotrope-mediated stress). Inherent stabilities of the inactive (GDP-bound) and active (GTP-bound) forms contribute antagonistically to the difference in conformational stability whereas the GDP-bound protein is able to switch to a stable intermediate state, GTP-bound protein loses this ability. Partial perturbation of the protein fold reveals the underlying influence of the bound nucleotide providing an insight into the mechanism of activation. An extra stable, pretransition intermediate, 'empty pocket' state (conformationally active-state like) in the unfolding pathway of GDP-bound protein mimics a gating system - the activation process having to overcome this stable intermediate state. We demonstrate that a relatively more complex conformational fold of the GDP-bound protein is at the core of the gating system. We report capturing this threshold, 'metastable empty pocket' conformation (the gate) of α-subunit of G protein and hypothesize that the receptor activates the G protein by enabling it to achieve this structure through mild structural perturbation. © 2017 Federation of European Biochemical Societies.

Characterization of Mediator Complex and its Associated Proteins from Rice.

PubMed

Samanta, Subhasis; Thakur, Jitendra Kumar

2017-01-01

The Mediator complex is a multi-protein complex that acts as a molecular bridge conveying transcriptional messages from the cis element-bound transcription factor to the RNA Polymerase II machinery. It is found in all eukaryotes including members of the plant kingdom. Increasing number of reports from plants regarding different Mediator subunits involved in a multitude of processes spanning from plant development to environmental interactions have firmly established it as a central hub of plant regulatory networks. Routine isolation of Mediator complex in a particular species is a necessity because of many reasons. First, composition of the Mediator complex varies from species to species. Second, the composition of the Mediator complex in a particular species is not static under all developmental and environmental conditions. Besides this, at times, Mediator complex is used in in vitro transcription systems. Rice, a staple food crop of the world, is used as a model monocot crop. Realizing the need of a reliable protocol for the isolation of Mediator complex from plants, we describe here the isolation of Mediator complex from rice.

Silk flame retardant finish by ternary silica sol containing boron and nitrogen

NASA Astrophysics Data System (ADS)

Zhang, Qiang-hua; Chen, Guo-qiang; Xing, Tie-ling

2017-11-01

A ternary flame retardant sol system containing Si, B and N was prepared via sol gel method using tetraethoxysilane (TEOS) as a precursor, boric acid (H3BO3) and urea (CO(NH2)2) as flame retardant additives and then applied to silk fabric flame retardant finish. The FT-IR and SEM results showed that the nitrogen-boron-silica ternary sol was successfully prepared and entrapped onto the surface of silk fibers. The limiting oxygen index (LOI) test indicated that the silk fabric treated with 24% boric acid and 6% urea (relative to the TEOS) doped ternary silica sol system performed excellent flame retardancy with the LOI value of 34.6%. Furthermore, in order to endow silk fabric with durable flame retardancy, the silk fabric was pretreated with 1,2,3,4-butanetetracarboxylic acid (BTCA) before the ternary sol system treatment. The BTCA pretreat ment applied to silk could effectively promote the washing durability of the ternary sol, and the LOI value of the treated sample after 10 times washing could still maintain at 30.8% compared with that of 31.0% before washing. Thermo gravimetric (TG), micro calorimeter combustion (MCC) and smoke density test results demonstrated that the thermal stability, heat release and smoke suppression of the nitrogen-boron-silica ternary system decreased somewhat compared with the boron-silica binary flame retardant system.

FIR Filter of DS-CDMA UWB Modem Transmitter

NASA Astrophysics Data System (ADS)

Kang, Kyu-Min; Cho, Sang-In; Won, Hui-Chul; Choi, Sang-Sung

This letter presents low-complexity digital pulse shaping filter structures of a direct sequence code division multiple access (DS-CDMA) ultra wide-band (UWB) modem transmitter with a ternary spreading code. The proposed finite impulse response (FIR) filter structures using a look-up table (LUT) have the effect of saving the amount of memory by about 50% to 80% in comparison to the conventional FIR filter structures, and consequently are suitable for a high-speed parallel data process.

Using a Ternary Diagram to Display a System's Evolving Energy Distribution

ERIC Educational Resources Information Center

Brazzle, Bob; Tapp, Anne

2016-01-01

A ternary diagram is a graphical representation used for systems with three components. They are familiar to mineralogists (who typically use them to categorize varieties of solid solution minerals such as feldspar) but are not yet widely used in the physics community. Last year the lead author began using ternary diagrams in his introductory…

Structure and superconductivity in the ternary silicide CaAlSi

NASA Astrophysics Data System (ADS)

Ma, Rong; Huang, Gui-Qin; Liu, Mei

2007-06-01

Using the linear response-linearized Muffin-tin orbital (LR-LMTO) method, we study the electronic band structure, phonon spectra, electron-phonon coupling and superconductivity for c-axis ferromagnetic-like (F-like) and antiferromagnetic-like (AF-like) structures in ternary silicide CaAlSi. The following conclusions are drawn from our calculations. If Al and Si atoms are assumed to arrange along the c axis in an F-like long-range ordering (-Al-Al-Al-and-Si-Si-Si-), one could obtain the ultrasoft B1g phonon mode and thus very strong electron-phonon coupling in CaAlSi. However, the appearance of imaginary frequency phonon modes indicates the instability of such a structure. For Al and Si atoms arranging along the c axis in an AF-like long-range ordering (-Al-Si-Al-), the calculated electron-phonon coupling constant is equal to 0.8 and the logarithmically averaged frequency is 146.8 K. This calculated result can correctly yield the superconducting transition temperature of CaAlSi by the standard BCS theory in the moderate electron-phonon coupling strength. We propose that an AF-like superlattice model for Al (or Si) atoms along the c direction may mediate the inconsistency estimated from theory and experiment, and explain the anomalous superconductivity in CaAlSi.

[Spectral Analysis of CdZnSe Ternary Quantum Dots Sensitized TiO2 Tubes and Its Application in Visible-Light Photocatalysis].

PubMed

Han, Zhi-zhong; Ren, Li-li; Pan, Hai-bo; Li, Chun-yan; Chen, Jing-hua; Chen, Jian-zhong

2015-11-01

In this work, cadmium nitrate hexahydrate [Cd(NO₃)₂ · 6H₂O] is as a source of cadmium, zinc nitrate [Zn(NO₃)₂] as a source of zinc source, and NaHSe as a source of selenium which was prepared through reducing the elemental selenium with sodium borohydride (NaBH₄). Then water-soluble Cd₁₋xZnxSe ternary quantum dots with different component were prepared by colloid chemistry. The as-prepared Cd₁₋xZnx Se ternary quantum dots exhibit stable fluorescent property in aqueous solution, and can still maintain good dispersivity at room temperature for four months. Powder X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM) were used to analyze crystal structure and morphology of the prepared Cd₁₋xZnxSe. It is found that the as-prepared ternary quantum dots are cubic phase, show as sphere, and the average of particle size is approximate 4 nm. The spectral properties and energy band structure of the as-prepared ternary quantum dots were modulated through changing the atom ratio of elements Zn and Cd. Compared with binary quantum dots CdSe and ZnSe, the ultraviolet-visible (UV-Visible) absorption spectrum and fluorescence (FL) emission spectrum of ternary quantum dots are both red-shift. The composites (Cd₀.₅ Zn₀.₅ Se@TNTs) of Cd₀.₅ Zn₀.₅ Se ternary quantum dots and TiO₂ nanotubes (TNTs) were prepared by directly immerging TNTs into quantum dots dispersive solution for 5 hours. TEM image shows that the Cd₀.₅ Zn₀.₅ Se ternary quantum dots were closely combined to nanotube surface. The infrared spectra show that the Ti-Se bond was formed between Cd₀.₅ Zn₀.₅ Se ternary quantum dots and TiO₂ nanotubes, which improve the stability of the composite. Compared to pristine TNTs, UV-Visible absorption spectrum of the composites is significantly enhanced in the visible region of light. And the absorption band edge of Cd₀.₅Zn₀.₅ Se@TNTs red-shift from 400 to 700 nm. The recombination of the photogenerated electron-hole pairs was restrained with the as-prepared ternary quantum dots. Therefore, the visible-light photocatalytic efficiency was greatly improved. After visible-light irradiation for 60 min, the degradation of Cd₀.₅ Zn₀.₅ Se@TNTs photocatalysts for RhB is nearly 100%, which is about 3. 3 times of that of pristine TNTs and 2. 5 times of that of pure Cd₀.₅ Zn₀.₅ Se ternary quantum dots, respectively.

Novel ternary composites: Preparation, performance and application of ZnFe2O4/TiO2/polyaniline

NASA Astrophysics Data System (ADS)

Li, Juanbi; Xiao, Qiushi; Li, Liangchao; Shen, Junhai; Hu, Diqiong

2015-03-01

A series of ZnFe2O4/TiO2/polyaniline ternary composites with excellent photocatalytic activity were successfully synthesized by chemical method. The phase composition, morphology, conductivity, electrical and magnetic performances of the as-samples were characterized by means of modern measurement technology. And the photocatalytic degradation activity tests for the samples were estimated using rhodamine B (RhB) and methyl orange (MO) as targeted pollutants. The results indicated that there existed some interactions between each component in the ternary composites, and the electrical conductivities and photocatalytic degradation activities of the ternary composites were improved due to the coating of polyaniline. Moreover, when the mass fraction of aniline was up to 50%, the ternary composite exhibited a great decontaminating (including photocatalytic degradation and adsorption) activity of on both MO and RhB and displayed an excellent reusability.

Synthesis and characterization of CdS-based ternary composite for enhanced visible light-driven photocatalysis

NASA Astrophysics Data System (ADS)

Singh, Arvind; Sinha, A. S. K.

2018-09-01

Active ternary graphite and alumina-supported cadmium sulphide (CdS) composite was synthesized by impregnation method followed by high-temperature solid-gas reaction and characterized by X-ray diffraction (XRD), photoluminescence spectroscopy (PL), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) techniques. The ternary CdS-graphite-alumina composite exhibited superior catalytic activity compared with the binary CdS-alumina composite due to its better visible-light absorption and higher charge separation. The ternary composite has a bed-type structure. It permits a greater interaction at the interface due to intimate contact between CdS and graphite in the ternary composite. This composite has a highly efficient visible light-driven photocatalytic activity for sustainable hydrogen production. It is also capable of degrading organic dyes in wastewater.

Organic Solar Cells beyond One Pair of Donor-Acceptor: Ternary Blends and More.

PubMed

Yang, Liqiang; Yan, Liang; You, Wei

2013-06-06

Ternary solar cells enjoy both an increased light absorption width, and an easy fabrication process associated with their simple structures. Significant progress has been made for such solar cells with demonstrated efficiencies over 7%; however, their fundamental working principles are still under investigation. This Perspective is intended to offer our insights on the three major governing mechanisms in these intriguing ternary solar cells: charge transfer, energy transfer, and parallel-linkage. Through careful analysis of exemplary cases, we summarize the advantages and limitations of these three major mechanisms and suggest future research directions. For example, incorporating additional singlet fission or upconversion materials into the energy transfer dominant ternary solar cells has the potential to break the theoretical efficiency limit in single junction organic solar cells. Clearly, a feedback loop between fundamental understanding and materials selection is in urgent need to accelerate the efficiency improvement of these ternary solar cells.

Early age strength increase of fly ash blended cement by a ternary hardening accelerating admixture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoang, Kien; Justnes, Harald; SINTEF Building and Infrastructure

The applicability of a combination of sodium thiocyanate (NaSCN), diethanolamine (DEA) and glycerol (Gly) with small dosages as a ternary hardening accelerating admixture for fly ash blended cement (OPC-FA) was studied. The ternary admixture induced higher early and later age mortar strength at both low (5 °C) and normal (20 °C) temperature. Despite used in lower dosage the ternary admixture led to higher strength of the investigated OPC-FA system than other chemicals (e.g. sodium sulfate). Results obtained from isothermal calorimetry, thermogravimetric analysis (TGA) and X-ray diffraction (XRD) showed that the ternary admixture accelerated the cement hydration and increased the amountmore » of AFm (notably calcium hemicarboaluminate hydrate) in the hydration products. A synergistic effect between the three components of the accelerator on the hydration of OPC-FA system was observed.« less

EF-1 alpha is a target site for an inhibitory effect of quercetin in the peptide elongation process.

PubMed

Marcinkiewicz, C; Gałasiński, W; Gindzieński, A

1995-01-01

The effect of quercetin (3,3',4',5,7-pentahydroxyflavone) on the polypeptide elongation system isolated from rat liver cells, was investigated. Quercetin inhibited [14C]leucine incorporation into proteins in vitro and the inhibitory effect is being directed towards the elongation factor eEF-1, but not to eEF-2 and ribosomes. Quercetin was found to form a complex with EF-1 alpha, which was inactive in GTP-dependent binding to ribosomes. It can be suggested that quercetin can block the total or the part of the domain of EF-1 alpha structure that is responsible for formation of the ternary complex EF-1 alpha-GTP-[14C]Phe-tRNA and therefore preventing formation of the quaternary complex with ribosomes.

Atomic description of the immune complex involved in heparin-induced thrombocytopenia

DOE PAGES

Cai, Zheng; Yarovoi, Serge V.; Zhu, Zhiqiang; ...

2015-09-22

Heparin-induced thrombocytopenia (HIT) is an autoimmune thrombotic disorder caused by immune complexes containing platelet factor 4 (PF4), antibodies to PF4 and heparin or cellular glycosaminoglycans (GAGs). Here we solve the crystal structures of the: (1) PF4 tetramer/fondaparinux complex, (2) PF4 tetramer/KKO-Fab complex (a murine monoclonal HIT-like antibody) and (3) PF4 monomer/RTO-Fab complex (a non-HIT anti-PF4 monoclonal antibody). Fondaparinux binds to the ‘closed’ end of the PF4 tetramer and stabilizes its conformation. This interaction in turn stabilizes the epitope for KKO on the ‘open’ end of the tetramer. Fondaparinux and KKO thereby collaborate to ‘stabilize’ the ternary pathogenic immune complex. Bindingmore » of RTO to PF4 monomers prevents PF4 tetramerization and inhibits KKO and human HIT IgG-induced platelet activation and platelet aggregation in vitro, and thrombus progression in vivo. Lastly, the atomic structures provide a basis to develop new diagnostics and non-anticoagulant therapeutics for HIT.« less

Core@shell@shell structured carbon-based magnetic ternary nanohybrids: Synthesis and their enhanced microwave absorption properties

NASA Astrophysics Data System (ADS)

Yang, Erqi; Qi, Xiaosi; Xie, Ren; Bai, Zhongchen; Jiang, Yang; Qin, Shuijie; Zhong, Wei; Du, Youwei

2018-05-01

High encapsulation efficiency of core@shell@shell structured carbon-based magnetic ternary nanohybrids have been synthesized in high yield by chemical vapor deposition of acetylene directly over octahedral-shaped Fe2O3 nanoparticles. By controlling the pyrolysis temperature, Fe3O4@Fe3C@carbon nanotubes (CNTs) and Fe@Fe3C@CNTs ternary nanohybrids could be selectively produced. The optimal RL values for the as-prepared ternary nanohybrids could reach up to ca. -46.7, -52.7 and -29.5 dB, respectively. The excellent microwave absorption properties of the obtaiend ternary nanohybrids were proved to ascribe to the quarter-wavelength matching model. Moreover, the as-prepared Fe@Fe3C@CNTs ternary nanohybrids displayed remarkably enhanced EM wave absorption capabilities compared to Fe3O4@Fe3C@CNTs due to their excellent dielectric loss abilities, good complementarities between the dielectric loss and the magnetic loss, and high attenuation constant. Generally, this strategy can be extended to explore other categories of core@shell or core@shell@shell structured carbon-based nanohybrids, which is very beneficial to accelerate the advancements of high performance MAMs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Xiaofei; Singh, Rajendra; Homann, Stefanie

The HIV-1 protein Nef inhibits antigen presentation by class I major histocompatibility complex (MHC-I). We determined the mechanism of this activity by solving the crystal structure of a protein complex comprising Nef, the MHC-I cytoplasmic domain (MHC-I CD) and the {mu}1 subunit of the clathrin adaptor protein complex 1. A ternary, cooperative interaction clamps the MHC-I CD into a narrow binding groove at the Nef-{mu}1 interface, which encompasses the cargo-recognition site of {mu}1 and the proline-rich strand of Nef. The Nef C terminus induces a previously unobserved conformational change in {mu}1, whereas the N terminus binds the Nef core tomore » position it optimally for complex formation. Positively charged patches on {mu}1 recognize acidic clusters in Nef and MHC-I. The structure shows how Nef functions as a clathrin-associated sorting protein to alter the specificity of host membrane trafficking and enable viral evasion of adaptive immunity.« less

A luminescent europium complex for the selective detection of trace amounts of aldicarb sulfoxide and prometryne

NASA Astrophysics Data System (ADS)

Anwar, Zeinab M.; Ibrahim, Ibrahim A.; Abdel-Salam, Enas T.; Kamel, Rasha M.; El-Asfoury, Mahmoud H.

2017-05-01

The interaction between luminescent Eu(TAN)2(Phen) ternary complex (where TAN = 4,4,4-Trifluoro-1-(2-naphthyl)-1,3-butanedione and Phen = 1,10 phenanthroline) with prometryne and aldicarb sulfoxide was studied by fluorescence spectroscopic technique. The results showed that the luminescence of europium complex was strongly quenched at λ = 614 nm by prometryne and aldicarb sulfoxide at pH 7.4 using PIPES buffer solution. The quenching mechanism was discussed to be a static quenching procedure, which was proved by the Stern Volmer (KSV) constants at different temperatures where the detection limits are 0.33 and 0.18 μmol L-1 for prometryne and aldicarb sulfoxide, respectively. According to Lineweaver-Burk equation at different temperatures, the thermodynamic parameters, ΔH, ΔS and ΔG associated with the interaction of the complex with the two pesticides were calculated.

Chiral recognition by formation of paramagnetic diastereomeric complexes

NASA Astrophysics Data System (ADS)

Scheffler, K.; Höfler, U.; Schuler, P.; Stegmann, H. B.

The chiral 4-(α-hydroxy-benzyl)-2,6-di-tert. butyl-phenoxyl has been examined in its racemic form in toluene and carbontetrachloride. On adding of chiral auxiliaries (R)-resp. (S)-N,N-dimethyl-1-phenylethylamine or (S)-phenylethyl-amine two different couplings of the β-proton are recorded by ENDOR spectroscopy. The experimental results are interpreted by a ternary equilibrium between radical, solvent and auxiliary. A model for the suggested association processes is given and equilibrium constants and corresponding enthalpies are calculated.

Structured codebook design in CELP

NASA Technical Reports Server (NTRS)

Leblanc, W. P.; Mahmoud, S. A.

1990-01-01

Codebook Excited Linear Protection (CELP) is a popular analysis by synthesis technique for quantizing speech at bit rates from 4 to 6 kbps. Codebook design techniques to date have been largely based on either random (often Gaussian) codebooks, or on known binary or ternary codes which efficiently map the space of (assumed white) excitation codevectors. It has been shown that by introducing symmetries into the codebook, good complexity reduction can be realized with only marginal decrease in performance. Codebook design algorithms are considered for a wide range of structured codebooks.

Phase Relations in Ternary Systems in the Subsolidus Region: Methods to Formulate Solid Solution Equations and to Find Particular Compositions

ERIC Educational Resources Information Center

Alvarez-Montan~o, Victor E.; Farías, Mario H.; Brown, Francisco; Mun~oz-Palma, Iliana C.; Cubillas, Fernando; Castillon-Barraza, Felipe F.

2017-01-01

A good understanding of ternary phase diagrams is required to advance and/or to reproduce experimental research in solid-state and materials chemistry. The aim of this paper is to describe the solutions to problems that appear when studying or determining ternary phase diagrams. A brief description of the principal features shown in phase diagrams…

Evaluation of the efficiency of continuous wavelet transform as processing and preprocessing algorithm for resolution of overlapped signals in univariate and multivariate regression analyses; an application to ternary and quaternary mixtures.

PubMed

Hegazy, Maha A; Lotfy, Hayam M; Mowaka, Shereen; Mohamed, Ekram Hany

2016-07-05

Wavelets have been adapted for a vast number of signal-processing applications due to the amount of information that can be extracted from a signal. In this work, a comparative study on the efficiency of continuous wavelet transform (CWT) as a signal processing tool in univariate regression and a pre-processing tool in multivariate analysis using partial least square (CWT-PLS) was conducted. These were applied to complex spectral signals of ternary and quaternary mixtures. CWT-PLS method succeeded in the simultaneous determination of a quaternary mixture of drotaverine (DRO), caffeine (CAF), paracetamol (PAR) and p-aminophenol (PAP, the major impurity of paracetamol). While, the univariate CWT failed to simultaneously determine the quaternary mixture components and was able to determine only PAR and PAP, the ternary mixtures of DRO, CAF, and PAR and CAF, PAR, and PAP. During the calculations of CWT, different wavelet families were tested. The univariate CWT method was validated according to the ICH guidelines. While for the development of the CWT-PLS model a calibration set was prepared by means of an orthogonal experimental design and their absorption spectra were recorded and processed by CWT. The CWT-PLS model was constructed by regression between the wavelet coefficients and concentration matrices and validation was performed by both cross validation and external validation sets. Both methods were successfully applied for determination of the studied drugs in pharmaceutical formulations. Copyright © 2016 Elsevier B.V. All rights reserved.

Proteomic Analysis of the Mediator Complex Interactome in Saccharomyces cerevisiae.

PubMed

Uthe, Henriette; Vanselow, Jens T; Schlosser, Andreas

2017-02-27

Here we present the most comprehensive analysis of the yeast Mediator complex interactome to date. Particularly gentle cell lysis and co-immunopurification conditions allowed us to preserve even transient protein-protein interactions and to comprehensively probe the molecular environment of the Mediator complex in the cell. Metabolic 15 N-labeling thereby enabled stringent discrimination between bona fide interaction partners and nonspecifically captured proteins. Our data indicates a functional role for Mediator beyond transcription initiation. We identified a large number of Mediator-interacting proteins and protein complexes, such as RNA polymerase II, general transcription factors, a large number of transcriptional activators, the SAGA complex, chromatin remodeling complexes, histone chaperones, highly acetylated histones, as well as proteins playing a role in co-transcriptional processes, such as splicing, mRNA decapping and mRNA decay. Moreover, our data provides clear evidence, that the Mediator complex interacts not only with RNA polymerase II, but also with RNA polymerases I and III, and indicates a functional role of the Mediator complex in rRNA processing and ribosome biogenesis.

Precursor Routes to Complex Ternary Intermetallics: Single-Crystal and Microcrystalline Preparation of Clathrate-I Na8Al8Si38 from NaSi + NaAlSi.

PubMed

Dong, Yongkwan; Chai, Ping; Beekman, Matt; Zeng, Xiaoyu; Tritt, Terry M; Nolas, George S

2015-06-01

Single crystals of the ternary clathrate-I Na8Al8Si38 were synthesized by kinetically controlled thermal decomposition (KCTD), and microcrystalline Na8Al8Si38 was synthesized by spark plasma sintering (SPS) using a NaSi + NaAlSi mixture as the precursor. Na8AlxSi46-x compositions with x ≤ 8 were also synthesized by SPS from precursor mixtures of different ratios. The crystal structure of Na8Al8Si38 was investigated using both Rietveld and single-crystal refinements. Temperature-dependent transport and UV/vis measurements were employed in the characterization of Na8Al8Si38, with diffuse-reflectance measurement indicating an indirect optical gap of 0.64 eV. Our results indicate that, when more than one precursor is used, both SPS and KCTD are effective methods for the synthesis of multinary inorganic phases that are not easily accessible by traditional solid-state synthesis or crystal growth techniques.

Droplet formation at the non-equilibrium water/water (w/w) interface

NASA Astrophysics Data System (ADS)

Chao, Youchuang; Mak, Sze Yi; Kong, Tiantian; Ding, Zijing; Shum, Ho Cheung

2017-11-01

The interfacial instability at liquid-liquid interfaces has been intensively studied in recent years due to their important role in nature and technology. Among them, two classic instabilities are Rayleigh-Taylor (RT) and double diffusive (DD) instabilities, which are practically relevant to many industrial processes, such as geologic CO2 sequestration. Most experimental and theoretical works have focused on RT or DD instability in binary systems. However, the study of such instability in complex systems, such as non-equilibrium ternary systems that involves mass-transfer-induced phase separation, has received less attention. Here, by using a ternary system known as the aqueous two-phase system (ATPS), we investigate experimentally the behavior of non-equilibrium water/water (w/w) interfaces in a vertically orientated Hele-Shaw cell. We observe that an array of fingers emerge at the w/w interface, and then break into droplets. We explore the instability using different concentrations of two aqueous phases. Our experimental findings are expected to inspire the mass production of all-aqueous emulsions in a simple setup.

Preparation of proton conducting membranes containing bifunctional titania nanoparticles

NASA Astrophysics Data System (ADS)

Aslan, Ayşe; Bozkurt, Ayhan

2013-07-01

Throughout this work, the synthesis and characterization of novel proton conducting nanocomposite membranes including binary and ternary mixtures of sulfated nano-titania (TS), poly(vinyl alcohol) (PVA), and nitrilotri(methyl phosphonic acid) (NMPA) are discussed. The materials were produced by means of two different approaches where in the first, PVA and TS (10-15 nm) were admixed to form a binary system. The second method was the ternary nanocomposite membranes including PVA/TS/NMPA that were prepared at several compositions to get PVA-TS-(NMPA) x . The interaction of functional nano particles and NMPA in the host matrix was explored by FT-IR spectroscopy. The homogeneous distribution of bifunctional nanoparticles in the membrane was confirmed by SEM micrographs. The spectroscopic measurements and water/methanol uptake studies suggested a complexation between PVA and NMPA, which inhibited the leaching of the latter. The thermogravimetry analysis results verified that the presence of TS in the composite membranes suppressed the formation of phosphonic acid anhydrides up to 150 °C. The maximum proton conductivity has been measured for PVA-TS-(NMPA)3 as 0.003 S cm-1 at 150 °C.

Stability of Ni-bsed bulk metallic glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokarz, Michelle L; Speakman, Scott A; Porter, Wallace D

Several ternary (Ni{sub x}Nb{sub y}Sn{sub z}) refractory alloy glasses (RAGs) were studied at elevated temperatures in order to assess the stability of the amorphous state, i.e. devitrification, and to identify subsequent phase transformations in these materials. differential scanning calorimetry (DSC) experiments indicated a complex phase transformation sequence with several distinct crystallization and melting events being recorded above the glass transition temperature, T{sub g}. Below T{sub g} the RAG samples were studied with an in situ environmental X-ray furnace facility, which allowed step-wise isothermal ramping experiments commencing at a temperature below the reduced temperature of T/T{sub g} {approx} 0.80. Distinct crystallinemore » phases were observed when T/T{sub g} {approx} 0.84 for ternary RAG alloys, while similar experiments on Zr-based Vit 106 glass alloys did not reveal any apparent phase separation until T/T{sub g} {approx} 0.96. The phase separation kinetics followed an Arrhenius type of relationship with Ni{sub 3}Sn, and Nb{sub 2}O{sub 5} being the principle crystalline precipitates.« less

Hydrogen storage compositions

DOEpatents

Li, Wen; Vajo, John J.; Cumberland, Robert W.; Liu, Ping

2011-04-19

Compositions for hydrogen storage and methods of making such compositions employ an alloy that exhibits reversible formation/deformation of BH.sub.4.sup.- anions. The composition includes a ternary alloy including magnesium, boron and a metal and a metal hydride. The ternary alloy and the metal hydride are present in an amount sufficient to render the composition capable of hydrogen storage. The molar ratio of the metal to magnesium and boron in the alloy is such that the alloy exhibits reversible formation/deformation of BH.sub.4.sup.- anions. The hydrogen storage composition is prepared by combining magnesium, boron and a metal to prepare a ternary alloy and combining the ternary alloy with a metal hydride to form the hydrogen storage composition.

Signal-off Electrochemiluminescence Biosensor Based on Phi29 DNA Polymerase Mediated Strand Displacement Amplification for MicroRNA Detection.

PubMed

Chen, Anyi; Gui, Guo-Feng; Zhuo, Ying; Chai, Ya-Qin; Xiang, Yun; Yuan, Ruo

2015-06-16

A target induced cycling strand displacement amplification (SDA) mediated by phi29 DNA polymerase (phi29) was first investigated and applied in a signal-off electrochemiluminescence (ECL) biosensor for microRNA (miRNA) detection. Herein, the target miRNA triggered the phi29-mediated SDA which could produce amounts of single-stranded DNA (assistant probe) with accurate and comprehensive nucleotide sequence. Then, the assistant probe hybridized with the capture probe and the ferrocene-labeled probe (Fc-probe) to form a ternary "Y" structure for ECL signal quenching by ferrocene. Therefore, the ECL intensity would decrease with increasing concentration of the target miRNA, and the sensitivity of biosensor would be promoted on account of the efficient signal amplification of the target induced cycling reaction. Besides, a self-enhanced Ru(II) ECL system was designed to obtain a stable and strong initial signal to further improve the sensitivity. The ECL assay for miRNA-21 detection is developed with excellent sensitivity of a concentration variation from 10 aM to 1.0 pM and limit of detection down to 3.3 aM.

CD4/CD8/Dendritic cell complexes in the spleen: CD8+ T cells can directly bind CD4+ T cells and modulate their response

PubMed Central

Barinov, Aleksandr; Galgano, Alessia; Krenn, Gerald; Tanchot, Corinne; Vasseur, Florence

2017-01-01

CD4+ T cell help to CD8+ T cell responses requires that CD4+ and CD8+ T cells interact with the same antigen presenting dendritic cell (Ag+DC), but it remains controversial whether helper signals are delivered indirectly through a licensed DC and/or involve direct CD4+/CD8+ T cell contacts and/or the formation of ternary complexes. We here describe the first in vivo imaging of the intact spleen, aiming to evaluate the first interactions between antigen-specific CD4+, CD8+ T cells and Ag+DCs. We show that in contrast to CD4+ T cells which form transient contacts with Ag+DC, CD8+ T cells form immediate stable contacts and activate the Ag+DC, acquire fragments of the DC membranes by trogocytosis, leading to their acquisition of some of the DC properties. They express MHC class II, and become able to present the specific Marilyn peptide to naïve Marilyn CD4+ T cells, inducing their extensive division. In vivo, these CD8+ T cells form direct stable contacts with motile naïve CD4+ T cells, recruiting them to Ag+DC binding and to the formation of ternary complexes, where CD4+ and CD8+ T cells interact with the DC and with one another. The presence of CD8+ T cells during in vivo immune responses leads to the early activation and up-regulation of multiple functions by CD4+ T lymphocytes. Thus, while CD4+ T cell help is important to CD8+ T cell responses, CD8+ T cells can interact directly with naïve CD4+ T cells impacting their recruitment and differentiation. PMID:28686740

Computational Insights into the Interactions between Calmodulin and the c/nSH2 Domains of p85α Regulatory Subunit of PI3Kα: Implication for PI3Kα Activation by Calmodulin.

PubMed

Ni, Duan; Liu, Dingyu; Zhang, Jian; Lu, Shaoyong

2018-01-04

Calmodulin (CaM) and phosphatidylinositide-3 kinase (PI3Kα) are well known for their multiple roles in a series of intracellular signaling pathways and in the progression of several human cancers. Crosstalk between CaM and PI3Kα has been an area of intensive research. Recent experiments have shown that in adenocarcinoma, K-Ras4B is involved in the CaM-PI3Kα crosstalk. Based on experimental results, we have recently put forward a hypothesis that the coordination of CaM and PI3Kα with K-Ras4B forms a CaM-PI3Kα-K-Ras4B ternary complex, which leads to the formation of pancreatic ductal adenocarcinoma. However, the mechanism for the CaM-PI3Kα crosstalk is unresolved. Based on molecular modeling and molecular dynamics simulations, here we explored the potential interactions between CaM and the c/nSH2 domains of p85α subunit of PI3Kα. We demonstrated that CaM can interact with the c/nSH2 domains and the interaction details were unraveled. Moreover, the possible modes for the CaM-cSH2 and CaM-nSH2 interactions were uncovered and we used them to construct a complete CaM-PI3Kα complex model. The structural model of CaM-PI3Kα interaction not only offers a support for our previous ternary complex hypothesis, but also is useful for drug design targeted at CaM-PI3Kα protein-protein interactions.

Lactate Dehydrogenase Undergoes a Substantial Structural Change to Bind its Substrate

PubMed Central

Qiu, Linlin; Gulotta, Miriam; Callender, Robert

2007-01-01

Employing temperature-jump relaxation spectroscopy, we investigate the kinetics and thermodynamics of the formation of a very early ternary binding intermediate formed when lactate dehydrogenase (LDH) binds a substrate mimic on its way to forming the productive LDH/NADH·substrate Michaelis complex. Temperature-jump scans show two distinct submillisecond processes are involved in the formation of this ternary binding intermediate, called the encounter complex here. The on-rate of the formation of the encounter complex from LDH/NADH with oxamate (a substrate mimic) is determined as a function of temperature and in the presence of small concentrations of a protein destabilizer (urea) and protein stabilizer (TMAO). It shows a strong temperature dependence with inverse Arrhenius behavior and a temperature-dependent enthalpy (heat capacity of 610 ± 84 cal/Mol K), is slowed in the presence of TMAO and speeded up in the presence of urea. These results suggest that LDH/NADH occupies a range of conformations, some competent to bind substrate (open structure; a minority population) and others noncompetent (closed), in fast equilibrium with each other in accord with a select fit model of binding. From the thermodynamic results, the two species differ in the rearrangement of low energy hydrogen bonds as would arise from changes in internal hydrogen bonding and/or increases in the solvation of the protein structure. The binding-competent species can bind ligand at or very near diffusion-limited speeds, suggesting that the binding pocket is substantially exposed to solvent in these species. This would be in contrast to the putative closed structure where the binding pocket resides deep within the protein interior. PMID:17483169

Differential impact of ionic and coordinate covalent chromium (Cr)-DNA binding on DNA replication.

PubMed

Fornsaglio, Jamie L; O'Brien, Travis J; Patierno, Steven R

2005-11-01

The reactive species produced by the reduction of Cr(VI), particularly Cr(III), can form both ionic and coordinate covalent complexes with DNA. These Cr(III)-DNA interactions consist of Cr-DNA monoadducts, Cr-DNA ternary adducts, and Cr-DNA interstrand cross-links (Cr-ICLs), the latter of which are DNA polymerase arresting lesions (PALs). We sought to determine the impact of Cr-DNA interactions on the formation of replication blocking lesions in S. cerevisiae using a PCR-based method. We found that target sequence (TS) amplification using DNA isolated from Cr(VI)-treated yeast actually increased as a function of Cr(VI) concentration. Moreover, the enhanced TS amplification was reproduced in vitro using Cr(III)-treated DNA. In contrast, PCR amplification of TS from DNA isolated from yeast exposed to equitoxic doses of the inorganic DNA cross-linking agent cisplatin (CDDP), was decreased in a concentration-dependent manner. This paradox suggested that a specific Cr-DNA interaction, such as an ionic Cr-DNA complex, was responsible for the enhanced TS amplification, thereby masking the replication-blocking effect of certain ternary Cr-DNA adducts (i.e. interstrand cross-links). To test this possibility, we removed ionically associated Cr from the DNA using salt extraction prior to PCR analysis. This procedure obviated the increased amplification and revealed a dose-dependent decrease in TS amplification and an increase in Cr-PALs. These data from DNA analyzed ex vivo after treatment of intact cells indicate that ionic interactions of Cr with DNA result in increased DNA amplification whereas coordinate-covalent Cr-DNA complexes lead to formation of Cr-PALs. Thus, these results suggest that treatment of living cells with Cr(VI) leads to two modes of Cr-binding, which may have conflicting effects on DNA replication.

Regulation of metabolism by the Mediator complex.

PubMed

Youn, Dou Yeon; Xiaoli, Alus M; Pessin, Jeffrey E; Yang, Fajun

2016-01-01

The Mediator complex was originally discovered in yeast, but it is conserved in all eukaryotes. Its best-known function is to regulate RNA polymerase II-dependent gene transcription. Although the mechanisms by which the Mediator complex regulates transcription are often complicated by the context-dependent regulation, this transcription cofactor complex plays a pivotal role in numerous biological pathways. Biochemical, molecular, and physiological studies using cancer cell lines or model organisms have established the current paradigm of the Mediator functions. However, the physiological roles of the mammalian Mediator complex remain poorly defined, but have attracted a great interest in recent years. In this short review, we will summarize some of the reported functions of selective Mediator subunits in the regulation of metabolism. These intriguing findings suggest that the Mediator complex may be an important player in nutrient sensing and energy balance in mammals.

Plant Mediator complex and its critical functions in transcription regulation.

PubMed

Yang, Yan; Li, Ling; Qu, Li-Jia

2016-02-01

The Mediator complex is an important component of the eukaryotic transcriptional machinery. As an essential link between transcription factors and RNA polymerase II, the Mediator complex transduces diverse signals to genes involved in different pathways. The plant Mediator complex was recently purified and comprises conserved and specific subunits. It functions in concert with transcription factors to modulate various responses. In this review, we summarize the recent advances in understanding the plant Mediator complex and its diverse roles in plant growth, development, defense, non-coding RNA production, response to abiotic stresses, flowering, genomic stability and metabolic homeostasis. In addition, the transcription factors interacting with the Mediator complex are also highlighted. © 2015 Institute of Botany, Chinese Academy of Sciences.

Bactericidal action of binary and ternary mixtures of carvacrol, thymol, and eugenol against Listeria innocua.

PubMed

García-García, Rebeca; López-Malo, Aurelio; Palou, Enrique

2011-03-01

The bactericidal effect of 3 natural agents (carvacrol, thymol, and eugenol) was evaluated as well as their binary and ternary mixtures on Listeria innocua inactivation in liquid model systems. Minimal bactericidal concentrations (MBC) of these agents were determined, and then binary and ternary mixtures were evaluated. Culture media were inoculated with L. innocua and incubated for 72 h at 35 °C. Turbidity of studied systems were determined every 24 h. The most effective individual antimicrobial agent was carvacrol, followed by thymol and then eugenol with MBCs of 150, 250, and 450 mg kg(-1), respectively. It was observed that the most effective binary mixture was 75 mg kg(-1) carvacrol and 62.5 mg kg(-1) thymol. Furthermore, the ternary mixture carvacrol-thymol-eugenol in concentrations of 75, 31.25, and 56.25 mg kg(-1), correspondingly, was the most effective for L. innocua inactivation. Several binary and ternary mixtures of these 3 natural antimicrobial agents worked adequately to inactivate L. innocua.

Temperature Dependence of Densities and Excess Molar Volumes of the Ternary Mixture (1-Butanol + Chloroform + Benzene) and its Binary Constituents (1-Butanol + Chloroform and 1-Butanol + Benzene)

NASA Astrophysics Data System (ADS)

Smiljanić, Jelena D.; Kijevčanin, Mirjana Lj.; Djordjević, Bojan D.; Grozdanić, Dušan K.; Šerbanović, Slobodan P.

2008-04-01

Densities ρ of the 1-butanol + chloroform + benzene ternary mixture and the 1-butanol + chloroform and 1-butanol + benzene binaries have been measured at six temperatures (288.15, 293.15, 298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure, using an oscillating U-tube densimeter. From these densities, excess molar volumes ( V E) were calculated and fitted to the Redlich Kister equation for all binary mixtures and to the Nagata and Tamura equation for the ternary system. The Radojković et al. equation has been used to predict excess molar volumes of the ternary mixtures. Also, V E data of the binary systems were correlated by the van der Waals (vdW1) and Twu Coon Bluck Tilton (TCBT) mixing rules coupled with the Peng Robinson Stryjek Vera (PRSV) equation of state. The prediction and correlation of V E data for the ternary system were performed by the same models.

Characterization of the Ternary Compound Pd5Pt3Ni2 for PEMFC Cathode Electrocatalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jarvis, Karalee; Zhao, J; Allard Jr, Lawrence Frederick

2010-01-01

Research on proton exchange membrane fuel cells (PEMFC) has increased over the last decade due to an increasing demand for alternative energy solutions. Most PEMFCs use Pt on carbon support as electrocatalysts for oxygen reduction reactions (ORR) [1]. Due to the high cost of Pt, there is a strong drive to develop less expensive catalysts that meet or exceed the performance of Pt. Binary and ternary Pt alloys with less expensive metals are a possible route [1]. In this work, a ternary alloy with composition Pd5Pt3Ni2 was studied as a potential cathode material. Preliminary results showed similar catalytic performance tomore » pure Pt in single-cell tests. However, to enhance its performance, it is necessary to understand how this ternary catalyst behaves during fuel cell operation. Various electron microscopy techniques were used to characterize the ternary Pd5Pt3Ni2 catalysts within the membrane-electrode assembly (MEA) both before and after fuel cell operation.« less

Effect of Ni-Co Ternary Molten Salt Catalysts on Coal Catalytic Pyrolysis Process

NASA Astrophysics Data System (ADS)

Cui, Xin; Qi, Cong; Li, Liang; Li, Yimin; Li, Song

2017-08-01

In order to facilitate efficient and clean utilization of coal, a series of Ni-Co ternary molten salt crystals are explored and the catalytic pyrolysis mechanism of Datong coal is investigated. The reaction mechanisms of coal are achieved by thermal gravimetric analyzer (TGA), and a reactive kinetic model is constructed. The microcosmic structure and macerals are observed by scanning electron microscope (SEM). The catalytic effects of ternary molten salt crystals at different stages of pyrolysis are analyzed. The experimental results show that Ni-Co ternary molten salt catalysts have the capability to bring down activation energy required by pyrolytic reactions at its initial phase. Also, the catalysts exert a preferable catalytic action on macromolecular structure decomposition and free radical polycondensation reactions. Furthermore, the high-temperature condensation polymerization is driven to decompose further with a faster reaction rate by the additions of Ni-Co ternary molten salt crystal catalysts. According to pyrolysis kinetic research, the addition of catalysts can effectively decrease the activation energy needed in each phase of pyrolysis reaction.