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Sample records for active ternary complex

  1. The active site of RNA polymerase II participates in transcript cleavage within arrested ternary complexes.

    PubMed Central

    Rudd, M D; Izban, M G; Luse, D S

    1994-01-01

    RNA polymerase II may become arrested during transcript elongation, in which case the ternary complex remains intact but further RNA synthesis is blocked. To relieve arrest, the nascent transcript must be cleaved from the 3' end. RNAs of 7-17 nt are liberated and transcription continues from the newly exposed 3' end. Factor SII increases elongation efficiency by strongly stimulating the transcript cleavage reaction. We show here that arrest relief can also occur by the addition of pyrophosphate. This generates the same set of cleavage products as factor SII, but the fragments produced with pyrophosphate have 5'-triphosphate termini. Thus, the active site of RNA polymerase II, in the presence of pyrophosphate, appears to be capable of cleaving phosphodiester linkages as far as 17 nt upstream of the original site of polymerization, leaving the ternary complex intact and transcriptionally active. Images PMID:8058756

  2. 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. PMID:26067934

  3. Ternary complexes in analytical chemistry.

    PubMed

    Babko, A K

    1968-08-01

    Reactions between a complex AB and a third component C do not always proceed by a displacement mechanism governed by the energy difference of the chemical bonds A-B and A-C. The third component often becomes part of the complex, forming a mixed co-ordination sphere or ternary complex. The properties of this ternary complex ABC are not additive functions of the properties of AB and AC. Such reactions are important in many methods in analytical chemistry, particularly in photometric analysis, extractive separation, masking, etc. The general properties of the four basic types of ternary complex are reviewed and examples given. The four types comprise the systems (a) metal ion, electronegative ligand, organic base, (b) one metal ion, two different electronegative ligands, (c) ternary heteropoly acids, and (d) two different metal ions, one ligand. PMID:18960358

  4. Tunable DNA cleavage activity promoted by copper(ii) ternary complexes with N-donor heterocyclic ligands.

    PubMed

    Bortolotto, T; Silva-Caldeira, P P; Pich, C T; Pereira-Maia, E C; Terenzi, H

    2016-06-01

    Several small molecules have the capacity to cleave DNA promptly at high yields, even under mild conditions. Usually, this activity has no constraints, occurring without external or user control. Here, we demonstrate that UV-light exposure can greatly enhance the DNA cleavage activity promoted by four ternary copper(ii) complexes. A remarkable photocontrolled activity was achieved, which may be interesting for chemical and biochemical applications. PMID:27168172

  5. Selective response of ternary complex factor Sap1a to different mitogen-activated protein kinase subgroups.

    PubMed Central

    Strahl, T; Gille, H; Shaw, P E

    1996-01-01

    Mitogenic and stres signals results in the activation of extracellular signal-regulated kinases (ERKs) and stress-activated protein kinase/c-Jun N-terminal kinases (SAPK/JNKs), respectively, which are two subgroups of the mitogen-activated protein kinases. A nuclear target of mitogen-activated protein (MAP) kinases is the ternary complex factor Elk-1, which underlies its involvement in the regulation of c-fos gene expression by mitogenic and stress signals. A second ternary complex factor, Sap1a, is coexpressed with Elk-1 in several cell types and shares attributes of Elk-1, the significance of which is not clear. Here we show that Sap1a is phosphorylated efficiently by ERKs but not by SAPK/JNKs. Serum response factor-dependent ternary complex formation by Sap1a is stimulated by ERK phosphorylation but not by SAPK/JNKs. Moreover, Sap1a-mediated transcription is activated by mitogenic signals but not by cell stress. These results suggest that Sap1a and Elk-1 have distinct physiological functions. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:8876175

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

    PubMed

    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)/2,2(1)-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

  7. Low and Room Temperature X-ray Structures of Protein Kinase A Ternary Complexes Shed New Light on Its Activity

    SciTech Connect

    Fisher, Zoe; Hanson, Leif; Kovalevsky, Andrey; Langan, Paul

    2012-01-01

    Posttranslational protein phosphorylation by protein kinase A (PKA) is a ubiquitous signaling mechanism which regulates many cellular processes. A low temperature X-ray structure of the PKA catalytic subunit (PKAc) ternary complex with ATP and a 20-residue peptidic inhibitor (IP20) at the physiological Mg2+ concentration of < 0.5mM revealed a single metal ion in the active site. The lack of a second metal in the low-temperature LT-PKAc-MgATP-IP20 renders the and phosphoryl groups of ATP to be very flexibile, with high thermal B-factors. Thus, the second metal is crucial for tight positioning of the terminal phosphoryl for transfer to a substrate, as demonstrated by comparison of the former structure with LT-PKAc- Mg2ATP-IP20 complex. In addition to the kinase activity, PKAc is also able to slowly catalyze the hydrolysis of ATP using a water molecule as a substrate. We found that at room temperature under X-ray irradiation ATP can be readily and completely hydrolyzed into ATP and a free phosphate ion in the crystals of the ternary complex LT-PKAc- Mg2ATP-IP20. The cleavage of ATP may be aided by X-ray-born free hydroxyl radicals, a very reactive chemical species, that move quickly 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 from its position in ATP toward Ala21 of IP20 that mimics the phosphorylation site. The phosphate, thus, pushes the peptidic inhibitor away from the product ADP, while resulting in dramatic conformational changes of IP20 terminal residues 24 and 25. X-ray structures of PKAc in complex with non-hydrolyzable ATP analog, AMPPNP, at both room and low temperatures demonstrated no temperature effects on the conformation and position of IP20.

  8. 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. ClO4] 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

  9. New binary and ternary platinum(II) formamidine complexes: Synthesis, characterization, structural studies and in-vitro antitumor activity

    NASA Astrophysics Data System (ADS)

    Soliman, Ahmed A.; Alajrawy, Othman I.; Attaby, Fawzy A.; Linert, W.

    2016-07-01

    A series of new binary and ternary platinum(II) complexes of the type [Pt(L1-4)Cl2].xH2O and [Pt(L1-4)ox].xH2O where L = formamidine ligands and ox = oxalate, have been synthesized and characterized by elemental analyses, magnetic susceptibility, UV-vis, infrared (IR), mass spectroscopy, thermal analysis and theoretical calculations. The spectroscopic data indicated that the formamidine ligands act as bidentate N2 donors. The complexes (1-8) are diamagnetic and the optimization of their structures indicated that the geometry is distorted square planar with Cl-Pt-Cl, O-Pt-O and N-Pt-N bond angles ranged 81.73°-95.82° which is acceptable for the heteroleptic complexes. The electronic energies (a.u.) of the complexes (-893.53 to -1989.84) indicate that the complexes are more stable than the ligands. The energies of the HOMO (-0.218 to -0.244) and LUMO (-.0111to -0.134) orbitals of the complexes were negative which indicates that the complexes are stable compounds. The dipole moment of the complexes (6.23-19.89 Debye) indicates that the complexes are polarized. The complexes are thermally stable as shown from their relatively higher overall activation energies (889-2066 kJ mol-1). The complexes are proved to have a good cytotoxicity with IC50 (μM) against MCF-7 (0.040-0.117), HCT-116 (0.085-0.119) and HepG-2 (0.058-0.131) cell lines, which open the field for further application as antitumor compounds.

  10. DNA topoisomerase II structures and anthracycline activity: insights into ternary complex formation.

    PubMed

    Dal Ben, D; Palumbo, M; Zagotto, G; Capranico, G; Moro, S

    2007-01-01

    DNA Topoisomerase II (Top2) is an essential nuclear enzyme that regulates the topological state of the DNA, and a target of very effective anticancer drugs including anthracycline antibiotics. Even though several aspects of drug activity against Top2 are understood, the drug receptor site is not yet known. Several Top2 mutants have altered drug sensitivity and have provided information of structural features determining drug action. Here, we have revised the published crystal structures of eukaryotic and prokaryotic Top2s and relevant biochemical investigations of enzyme activity and anthracycline action. In particular, we have considered Top2 mutations conferring resistance to anthracyclines and related agents. Following a previous study (Moro et al, Biochemistry, 2004; 43: 7503-13), we have then re-built a molecular model of the entire enzyme in complex with DNA after the cleavage reaction, and used it to define the receptor site of anthracyclines. The results suggest a model wherein the drug specifically contacts the cleaved DNA as well as amino acid residues of the enzyme CAP-like domain. The findings can explain several established structure-activity relationships of antitumour anthracyclines, and provide a framework for further developments of effective Top2 poison. PMID:17897022

  11. Resveratrol upregulates Egr-1 expression and activity involving extracellular signal-regulated protein kinase and ternary complex factors

    SciTech Connect

    Rössler, Oliver G.; Glatzel, Daniel; Thiel, Gerald

    2015-03-01

    Many intracellular functions have been attributed to resveratrol, a polyphenolic phytoalexin found in grapes and in other plants. Here, we show that resveratrol induces the expression of the transcription factor Egr-1 in human embryonic kidney cells. Using a chromosomally embedded Egr-1-responsive reporter gene, we show that the Egr-1 activity was significantly elevated in resveratrol-treated cells, indicating that the newly synthesized Egr-1 protein was biologically active. Stimulus-transcription coupling leading to the resveratrol-induced upregulation of Egr-1 expression and activity requires the protein kinases Raf and extracellular signal-regulated protein kinase ERK, while MAP kinase phosphatase-1 functions as a nuclear shut-off device that interrupts the signaling cascade connecting resveratrol stimulation with enhanced Egr-1 expression. On the transcriptional level, Elk-1, a key transcriptional regulator of serum response element-driven gene transcription, connects the intracellular signaling cascade elicited by resveratrol with transcription of the Egr-1 gene. These data were corroborated by the observation that stimulation of the cells with resveratrol increased the transcriptional activation potential of Elk-1. The SRE as well as the GC-rich DNA binding site of Egr-1 function as resveratrol-responsive elements. Thus, resveratrol regulates gene transcription via activation of the stimulus-regulated protein kinases Raf and ERK and the stimulus-responsive transcription factors TCF and Egr-1. - Highlights: • The plant polyphenol resveratrol upregulates Egr-1 expression and activity. • The stimulation of Egr-1 requires the protein kinases ERK and Raf. • Resveratrol treatment upregulates the transcriptional activation potential of Elk-1. • Resveratrol-induced stimulation of Egr-1 requires ternary complex factors. • Two distinct resveratrol-responsive elements were identified.

  12. Co(II), Ce(III) and UO 2(VI) bis-salicylatothiosemicarbazide complexes . Binary and ternary complexes, thermal studies and antimicrobial activity

    NASA Astrophysics Data System (ADS)

    El-Wahab, Z. H. Abd; Mashaly, Mahmoud M.; Salman, A. A.; El-Shetary, B. A.; Faheim, A. A.

    2004-10-01

    A series of new metal complexes of Co(II), Ce(III) and UO 2(VI), with the Schiff base ligand, H 2L, bis-salicylatothiosemicarbazide have been prepared in presence of different molar ratios of LiOH·H 2O as a deprotonating agent. Also, the ternary complexes were prepared by using 2-aminopyridine (2-Ampy) or oxalic acid (Ox) as a secondary ligand. All synthesized compounds were identified and confirmed by elemental analyses, molar conductivities, spectral (UV-Vis, IR, 1H NMR, mass) and magnetic moment measurements as well as TG-DSC technique. The changes in the selected vibrational absorption bands in IR and NMR spectra of the Schiff base ligand upon coordination indicate that, the ligand behaves as a neutral, monoanionic and/or dianionic tetradentate manner with ONNO donor sites. Conductance measurements suggest the non-electrolytic and 1:1 electrolytic nature of the metal complexes. Thermal studies suggest a mechanism for degradation of the metal complexes as function of temperature supporting the chelation modes, moreover, show the possibility of obtaining new complexes pyrolytically in the solid state which cannot be synthesized from solution. Antimicrobial screening of the free ligand and its binary complexes showed that, the free ligand and some metal complexes possess antimicrobial activities towards four type of bacteria and five types of fungi and these results were compared with eleven type of known antibiotics.

  13. Co(II), Ce(III) and UO2VI) bis-salicylatothiosemicarbazide complexes: binary and ternary complexes, thermal studies and antimicrobial activity.

    PubMed

    El-Wahab, Z H Abd; Mashaly, Mahmoud M; Salman, A A; El-Shetary, B A; Faheim, A A

    2004-10-01

    A series of new metal complexes of Co(II), Ce(III) and UO(2)(VI), with the Schiff base ligand, H2L, bis-salicylatothiosemicarbazide have been prepared in presence of different molar ratios of LiOH.H2O as a deprotonating agent. Also, the ternary complexes were prepared by using 2-aminopyridine (2-Ampy) or oxalic acid (Ox) as a secondary ligand. All synthesized compounds were identified and confirmed by elemental analyses, molar conductivities, spectral (UV-Vis, IR, 1H NMR, mass) and magnetic moment measurements as well as TG-DSC technique. The changes in the selected vibrational absorption bands in IR and NMR spectra of the Schiff base ligand upon coordination indicate that, the ligand behaves as a neutral, monoanionic and/or dianionic tetradentate manner with ONNO donor sites. Conductance measurements suggest the non-electrolytic and 1:1 electrolytic nature of the metal complexes. Thermal studies suggest a mechanism for degradation of the metal complexes as function of temperature supporting the chelation modes, moreover, show the possibility of obtaining new complexes pyrolytically in the solid state which cannot be synthesized from solution. Antimicrobial screening of the free ligand and its binary complexes showed that, the free ligand and some metal complexes possess antimicrobial activities towards four type of bacteria and five types of fungi and these results were compared with eleven type of known antibiotics. PMID:15350923

  14. 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.

  15. Elk3 from hamster--a ternary complex factor with strong transcriptional repressor activity.

    PubMed

    Hjortoe, Gertrud Malene; Weilguny, Dietmar; Willumsen, Berthe Marie

    2005-01-01

    Elk3 belongs to the Ets family of transcription factors, which are regulated by the Ras/mitogen-activated protein kinase-signaling pathway. In the absence of Ras, this protein is a strong inhibitor of transcription and may be directly involved in regulation of growth by downregulating the transcription of genes that are activated during entry into G1. We have isolated the Cricetulus griseus Elk3 gene from the Chinese hamster ovary (CHO) cell line and investigated the transcriptional potential of this factor. Transient transfections revealed that, in addition to its regulation of the c-fos promoter, Elk3 from CHO cells seems to inhibit other promoters controlling expression of proteins involved in G1/S phase progression; Cyclin D1 and DHFR. As has been described for the Elk3 homologs Net (Mouse) and Sap-2 (Human), the results of the present study further indicate that hamster Elk3 is a target of the Ras-Raf-MAPK pathway, and cotransfections with constitutively active H-ras relieves its negative transcriptional activity. No cells stably expressing exogenous Elk3 could be obtained, possibly due to an unspecified toxic or growth retarding effect. These findings support a possible role for Elk3 in growth regulation and reveal a high degree of homology for this protein across species. PMID:15684718

  16. Distinct effects of the UvrD helicase on topoisomerase-quinolone-DNA ternary complexes.

    PubMed

    Shea, M E; Hiasa, H

    2000-05-12

    Quinolone antibacterial drugs target both DNA gyrase (Gyr) and topoisomerase IV (Topo IV) and form topoisomerase-quinolone-DNA ternary complexes. The formation of ternary complexes results in the inhibition of DNA replication and leads to the generation of double-strand breaks and subsequent cell death. Here, we have studied the consequences of collisions between the UvrD helicase and the ternary complexes formed with either Gyr, Topo IV, or a mutant Gyr, Gyr (A59), which does not wrap the DNA strand around itself. We show (i) that Gyr-norfloxacin (Norf)-DNA and Topo IV-Norf-DNA, but not Gyr (A59)-Norf-DNA, ternary complexes inhibit the UvrD-catalyzed strand-displacement activity, (ii) that a single-strand break is generated at small portions of the ternary complexes upon their collisions with UvrD, and (iii) that the majority of Topo IV-Norf-DNA ternary complexes become nonreversible when UvrD collides with the Topo IV-Norf-DNA ternary complexes, whereas the majority of Gyr-Norf-DNA ternary complexes remain reversible after their collision with the UvrD helicase. These results indicated that different DNA repair mechanisms might be involved in the repair of Gyr-Norf-DNA and Topo IV-Norf-DNA ternary complexes. PMID:10799552

  17. Synthesis and Structure of a Ternary Copper(II) Complex with Mixed Ligands of Diethylenetriamine and Picrate: DNA/Protein-Binding Property and In Vitro Anticancer Activity Studies.

    PubMed

    Shi, Ya-Ning; Zheng, Kang; Zhu, Ling; Li, Yan-Tuan; Wu, Zhi-Yong; Yan, Cui-Wei

    2015-05-01

    Based on the importance of the design and synthesis of transition metal complexes with noncovalent DNA/protein-binding abilities in the field of metallo pharmaceuticals, a new mononuclear ternary copper(II) complex with mixed ligands of diethylenetriamine (dien) and picrate anion (pic), identified as [Cu(dien)(pic)](pic), was synthesized and characterized by elemental analysis, molar conductivity measurement, infrared spectrum, electronic spectral studies, and single-crystal X-ray diffractometry. The structure analysis reveals that the copper(II) complex crystallizes in the monoclinic space group P21 /c, and the copper(II) ion has a distorted square pyramidal coordination geometry. A two-dimensional supramolecular structure is formed through hydrogen bonds. The DNA/bovine serum albumin (BSA)-binding properties of the complex are explored, indicating that the complex can interact with herring sperm DNA via intercalation mode and bind to BSA responsible for quenching of tryptophan fluorescence by static quenching mechanism. The in vitro anticancer activity shows that the copper(II) complex is active against the selected tumor cell lines. PMID:25652782

  18. Synthesis, characterization, electrochemical studies and DFT calculations of amino acids ternary complexes of copper (II) with isonitrosoacetophenone. Biological activities

    NASA Astrophysics Data System (ADS)

    Tidjani-Rahmouni, Nabila; Bensiradj, Nour el Houda; Djebbar, Safia; Benali-Baitich, Ouassini

    2014-10-01

    Three mixed complexes having formula [Cu(INAP)L(H2O)2] where INAP = deprotonated isonitrosoacetophenone and L = deprotonated amino acid such as histidine, phenylalanine and tryptophan have been synthesized. They have also been characterized using elemental analyses, molar conductance, UV-Vis, IR and ESR spectra. The value of molar conductance indicates them to be non-electrolytes. The spectral studies support the binding of the ligands with two N and two O donor sites to the copper (II) ion, giving an arrangement of N2O2 donor groups. Density Functional Theory (DFT) calculations were applied to evaluate the cis and trans coordination modes of the two water molecules. The trans form was shown to be energetically more stable than the cis one. The ESR data indicate that the covalent character of the metal-ligand bonding in the copper (II) complexes increases on going from histidine to phenylalanine to tryptophan. The electrochemical behavior of the copper (II) complexes was determined by cyclic voltammetry which shows that the chelate structure and electron donating effects of the ligands substituent are among the factors influencing the redox potentials of the complexes. The antimicrobial activities of the complexes were evaluated against several pathogenic microorganisms to assess their antimicrobial potentials. The copper complexes were found to be more active against Gram-positive than Gram-negative bacteria. Furthermore, the antioxidant efficiencies of the metal complexes were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. The antioxidant activity of the complexes indicates their moderate scavenging activity against the radical DPPH.

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

    SciTech Connect

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

    2012-07-01

    ATP bound in the active site of protein kinase A is readily hydrolysed to ADP and free phosphate by X-ray irradiation at room temperature. The phosphate ion observed in the active site causes a dramatic conformational change of the bound peptide inhibitor. 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{sup 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{sub 2}ATP–IP20 complex obtained at high Mg{sup 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{sub 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

  20. Anticancer activity and computational modeling of ternary copper (II) complexes with 3-indolecarboxylic acid and 1,10-phenanthroline.

    PubMed

    Zhang, Zhen; Wang, Huiyun; Wang, Qibao; Yan, Maocai; Wang, Huannan; Bi, Caifeng; Sun, Shanshan; Fan, Yuhua

    2016-08-01

    Metal-containing compounds have been extensively studied for many years as potent proteasome inhibitors. The 20S proteasome, the main component of the ubiquitin proteasome pathway, is one of the excellent targets in anticancer drug development. We recently reported that several copper complexes were able to inhibit cancer-special proteasome and induce cell death in human cancer cells. However, the involved molecular mechanism is not known yet. We therefore synthesized three copper complexes and investigated their abilities on inhibiting proteasome activity and inducting apoptosis in human breast cancer cells. Furthermore, we employed molecular dockings to analyze the possible interaction between the synthetic copper complexes and the β5 subunit of proteasome which only reflects the chymotrypsin-like activity. Our results demonstrate that three Cu(II) complexes possess potent proteasome inhibition capability in a dose-dependent and time-dependent manner in MDA-MB-231 human breast cancer cells. They could bind to the β5 subunit of the 20S proteasome, which consequently cause deactivation of the proteasome and tumor cell death. The present study is significant for providing important theoretical basis for design and synthesis of anticancer drugs with low toxicity, high efficiency and high selectivity. PMID:27278680

  1. Ternary Inclusion Complexes of Rifaximin with β-Cyclodextrin and Sodium Deoxycholate for Solubility Enhancement.

    PubMed

    Kaur, Parminderjit; Rampal, Ankit; Singh Bedi, Preet M; Bedi, Neena

    2015-01-01

    Rifaximin is a rifamycin derivative, having extremely poor aqueous solubility. The objective of present study was to improve dissolution and solubility of drug using β-cyclodextrin inclusion complexes and also to evaluate the effect of presence of sodium deoxycholate on solubilization efficiency of β-cyclodextrin. The stochiometry of inclusion complexes of binary (drug-cyclodextrin) and ternary system (drug-cyclodextrin-sodium deoxycholate) were determined by phase solubility studies at 25 °C. The stability constants (K1:2) calculated from phase solubility analysis were 126 M(-1) and 267 M(-1) for binary and ternary systems respectively. The inclusion complexes were prepared by solvent evaporation method with the inclusion efficiency of 43% and 56.9% for binary and ternary systems followed by their characterization using fourier transform infrared spectroscopy, X-ray diffractometry, differential scanning calorimetry and in-vitro antibacterial activity. The solubility of drug was improved by 4.3 and 11.9 folds in binary and ternary inclusion complexes, respectively. Therefore, it can be concluded that the ternary inclusion complexation having better solubilization efficiency as compared to binary complexation. PMID:26279215

  2. Synthesis, characterization, and antitumor activity of three ternary dinuclear copper (II) complexes with a reduced Schiff base ligand and diimine coligands in vitro and in vivo.

    PubMed

    Jia, Lei; Xu, Jun; Zhao, Xiaolei; Shen, Shanshan; Zhou, Tao; Xu, Zhouqing; Zhu, Taofeng; Chen, Ruhua; Ma, Tieliang; Xie, Jing; Dong, Kun; Huang, Jiancui

    2016-06-01

    Three ternary copper (II) complexes containing 1,10-phenanthroline (phen, 1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 2) and dipyrido[3,2-a:2',3'-c]phenazine (dppz, 3), with the formulation [Cu2(NCL)2(H4PASP)]·4.5H2O (1-3) (where NCL=the diimine coligand, H4PASP=N,N'-(p-xylylene)di-2-aminosuccinic acid), were isolated and characterized. The binding of these complexes with calf thymus DNA was studied using UV-visible absorption titration, emission, and circular dichroism spectroscopy, among other methods. The changes in physicochemical properties that occurred upon binding of these complexes with DNA indicate that binding occurs primarily through intercalative interactions. Human tumor cell lines HeLa, PC3, and HepG2 were treated with the copper(II) complexes in vitro and cell survival rate was assessed by 3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay and crystal violet survival assay. Flow cytometry was performed on treated cells labeled with AnnexinV/Propidium Iodide staining to determine rates of apoptosis. Western blot was performed to determine the expression levels of the apoptotic markers p53, Bax, and Bcl-2. The complexes reduced cell viability and induced apoptosis in cells of human tumor cell lines in a dose-dependent manner. In addition, using a nude mouse xenograft model, we found that the three ternary copper (II) complexes inhibited human tumor cell growth in vivo. In conclusion, these novel synthetic copper complexes have profound antitumor effects on human tumor cells and are promising therapeutic agents for human tumors. PMID:26974885

  3. RNA polymerase II ternary transcription complexes generated in vitro.

    PubMed Central

    Ackerman, S; Bunick, D; Zandomeni, R; Weinmann, R

    1983-01-01

    Ternary transcription complexes have been formed with a HeLa cell extract, a specific DNA template, and nucleoside triphosphates. The assay depends on the formation of sarkosyl-resistant initiation complexes which contain RNA polymerase II, template DNA, and radioactive nucleoside triphosphates. Separation from the other elements in the in vitro reaction is achieved by electrophoresis in agarose - 0.25% sarkosyl gels. The mobility of the ternary complexes in this system cannot be distinguished from naked DNA. Formation of this complex is dependent on all parameters necessary for faithful in vitro transcription. Complexes are formed with both the plasmid vector and the specific adenovirus DNA insert containing a eucaryotic promoter. The formation of the complex on the eucaryotic DNA is sequence-dependent. An undecaribonucleotide predicted from the template DNA sequence remains associated with the DNA in the ternary complex and can be isolated if the chain terminator 3'-0-methyl GTP is used, or after T1 ribonuclease treatment of the RNA, or if exogenous GTP is omitted from the in vitro reaction. This oligonucleotide is not detected in association with the plasmid vector. Phosphocellulose fractionation of the extract indicates that at least one of the column fractions required for faithful runoff transcription is required for complex formation. A large molar excess of abortive initiation events was detected relative to the level of productive transcription events, indicating a 40-fold higher efficiency of transcription initiation vs. elongation. Images PMID:6193489

  4. Do aqueous ternary complexes influence the TALSPEAK process?

    SciTech Connect

    Leggett, C. j.; Liu, G.; Jensen, M. P.; Chemical Sciences and Engineering Division

    2010-01-01

    The aqueous speciation of trivalent lanthanide and actinide cations in solutions containing DTPA (diethylenetriamine-N,N,N',N',N'-pentaacetic acid) and lactic acid were studied under conditions representative of the TALSPEAK process. Spectrophotometric titrations, fluorescence spectroscopy, and thermometric titrations were used to search for indications of ternary metal-DTPA-lactate complexes. The addition of lactate anions to metal-DTPA complexes was undetectable by any of these techniques, even at free lactate concentrations of 0.75 M. Although lactic acid is necessary for the optimal performance of the TALSPEAK process, we find that the fractions of aqueous ternary Ln3+/An3+-DTPA-lactate complexes are far too low to account for the observed acid dependence of TALSPEAK metal extraction.

  5. Formation of a Ternary Complex for Selenocysteine Biosynthesis in Bacteria.

    PubMed

    Silva, Ivan R; Serrão, Vitor H B; Manzine, Livia R; Faim, Lívia M; da Silva, Marco T A; Makki, Raphaela; Saidemberg, Daniel M; Cornélio, Marinônio L; Palma, Mário S; Thiemann, Otavio H

    2015-12-01

    The synthesis of selenocysteine-containing proteins (selenoproteins) involves the interaction of selenocysteine synthase (SelA), tRNA (tRNA(Sec)), selenophosphate synthetase (SelD, SPS), a specific elongation factor (SelB), and a specific mRNA sequence known as selenocysteine insertion sequence (SECIS). Because selenium compounds are highly toxic in the cellular environment, the association of selenium with proteins throughout its metabolism is essential for cell survival. In this study, we demonstrate the interaction of SPS with the SelA-tRNA(Sec) complex, resulting in a 1.3-MDa ternary complex of 27.0 ± 0.5 nm in diameter and 4.02 ± 0.05 nm in height. To assemble the ternary complex, SPS undergoes a conformational change. We demonstrated that the glycine-rich N-terminal region of SPS is crucial for the SelA-tRNA(Sec)-SPS interaction and selenoprotein biosynthesis, as revealed by functional complementation experiments. Taken together, our results provide new insights into selenoprotein biosynthesis, demonstrating for the first time the formation of the functional ternary SelA-tRNA(Sec)-SPS complex. We propose that this complex is necessary for proper selenocysteine synthesis and may be involved in avoiding the cellular toxicity of selenium compounds. PMID:26378233

  6. Myeloperoxidase, paraoxonase-1, and HDL form a functional ternary complex.

    PubMed

    Huang, Ying; Wu, Zhiping; Riwanto, Meliana; Gao, Shengqiang; Levison, Bruce S; Gu, Xiaodong; Fu, Xiaoming; Wagner, Matthew A; Besler, Christian; Gerstenecker, Gary; Zhang, Renliang; Li, Xin-Min; DiDonato, Anthony J; Gogonea, Valentin; Tang, W H Wilson; Smith, Jonathan D; Plow, Edward F; Fox, Paul L; Shih, Diana M; Lusis, Aldons J; Fisher, Edward A; DiDonato, Joseph A; Landmesser, Ulf; Hazen, Stanley L

    2013-09-01

    Myeloperoxidase (MPO) and paraoxonase 1 (PON1) are high-density lipoprotein-associated (HDL-associated) proteins mechanistically linked to inflammation, oxidant stress, and atherosclerosis. MPO is a source of ROS during inflammation and can oxidize apolipoprotein A1 (APOA1) of HDL, impairing its atheroprotective functions. In contrast, PON1 fosters systemic antioxidant effects and promotes some of the atheroprotective properties attributed to HDL. Here, we demonstrate that MPO, PON1, and HDL bind to one another, forming a ternary complex, wherein PON1 partially inhibits MPO activity, while MPO inactivates PON1. MPO oxidizes PON1 on tyrosine 71 (Tyr71), a modified residue found in human atheroma that is critical for HDL binding and PON1 function. Acute inflammation model studies with transgenic and knockout mice for either PON1 or MPO confirmed that MPO and PON1 reciprocally modulate each other's function in vivo. Further structure and function studies identified critical contact sites between APOA1 within HDL, PON1, and MPO, and proteomics studies of HDL recovered from acute coronary syndrome (ACS) subjects revealed enhanced chlorotyrosine content, site-specific PON1 methionine oxidation, and reduced PON1 activity. HDL thus serves as a scaffold upon which MPO and PON1 interact during inflammation, whereupon PON1 binding partially inhibits MPO activity, and MPO promotes site-specific oxidative modification and impairment of PON1 and APOA1 function. PMID:23908111

  7. 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

  8. Ternary Complexes of Iron, Amyloid-β and Nitrilotriacetic Acid

    PubMed Central

    Jiang, Dianlu; Li, Xiangjun; Williams, Renee; Patel, Sveti; Men, Lijie; Wang, Yinsheng; Zhou, Feimeng

    2009-01-01

    The interaction of amyloid-β (Aβ) and redox-active metals, two important biomarkers present in the senile plaques of AD brain, has been suggested to either enhance the Aβ aggregation or facilitate the generation of reactive oxygen species (ROS). The present study investigates the nature of the interaction between the metal-binding domain of Aβ, viz, Aβ(1-16), and the Fe(III) or Fe(II) complex with nitrilotriacetic acid (NTA). Using electrospray ionization mass spectrometry (ESI-MS), the formation of a ternary complex of Aβ(1-16), Fe(III), and NTA with a stoichiometry of 1:1:1 was identified. MS also revealed that the NTA moiety can be detached via collision-induced dissociation. The cumulative dissociation constants of both Aβ-Fe(III)-NTA and Aβ-Fe(II)-NTA were deduced to be 6.3 × 10-21 M2 and 5.0 × 10-12 M2, respectively, via measuring the fluorescence quenching of the sole tyrosine residue on Aβ upon the complex formation. The redox properties of these two complexes were investigated by cyclic voltammetry. The redox potential of the Aβ-Fe(III)-NTA complex was found to be 0.03 V vs. Ag/AgCl, which is negatively shifted by 0.54 V when compared to the redox potential of free Fe(III)/Fe(II). Despite such a large potential modulation, the redox potential of the Aβ-Fe(III)-NTA complex is still sufficiently high for occurrence of a range of redox reactions with cellular species. Aβ-Fe(II)-NTA electrogenerated from Aβ-Fe(III)-NTA was also found to catalyze the reduction of oxygen to produce H2O2. These findings provide significant insight into the role of iron and Aβ in the development of AD. The binding of iron by Aβ modulates the redox potential to a level where its redox cycling occurs. In the presence of a biological reductant (antioxidant), redox cycling of iron could disrupt the redox balance within the cellular milieu. As a consequence, not only ROS is continuously produced, but also oxygen and biological reductants can be depleted. A cascade of

  9. Crystal Structure of a Complete Ternary Complex of TCR, Superantigen and Peptide-MHC

    SciTech Connect

    Wang,L.; Zhao, Y.; Li, Z.; Guo, Y.; Jones, L.; Kranz, D.; Mourad, W.; Li, H.

    2007-01-01

    'Superantigens' (SAgs) trigger the massive activation of T cells by simultaneous interactions with MHC and TCR receptors, leading to human diseases. Here we present the first crystal structure, at 2.5-{angstrom} resolution, of a complete ternary complex between a SAg and its two receptors, HLA-DR1/HA and TCR. The most striking finding is that the SAg Mycoplasma arthritidis mitogen, unlike others, has direct contacts not only with TCR V{beta} but with TCR V{alpha}.

  10. Lethal synergism between organic and inorganic wood preservatives via formation of an unusual lipophilic ternary complex

    SciTech Connect

    Sheng, Zhi-Guo; Li, Yan; Fan, Rui-Mei; Chao, Xi-Juan; Zhu, Ben-Zhan

    2013-02-01

    We have shown previously that exposing bacteria to wood preservatives pentachlorophenol (PCP) and copper-containing compounds together causes synergistic toxicity. However, it is not clear whether these findings also hold true in mammalian cells; and if so, what is the underlying molecular mechanism? Here we show that PCP and a model copper complex bis-(1,10-phenanthroline) cupric (Cu(OP){sub 2}), could also induce synergistic cytotoxicity in human liver cells. By the single crystal X-ray diffraction and atomic absorption spectroscopy assay, the synergism was found to be mainly due to the formation of a lipophilic ternary complex with unusual structural and composition characteristics and subsequent enhanced cellular copper uptake, which markedly promoted cellular reactive oxygen species (ROS) production, leading to apoptosis by decreasing mitochondrial membrane potential, increasing pro-apoptotic protein expression, releasing cytochrome c from mitochondria and activating caspase-3, and -9. Analogous results were observed with other polychlorinated phenols (PCPs) and Cu(OP){sub 2}. Synergistic cytotoxicity could be induced by PCP/Cu(OP){sub 2} via formation of an unusual lipophilic complex in HepG2 cells. The formation of ternary complexes with similar lipophilic character could be of relevance as a general mechanism of toxicity, which should be taken into consideration especially when evaluating the toxicity of environmental pollutants found at currently-considered non- or sub-toxic concentrations. -- Highlights: ► The combination of PCP/Cu(OP){sub 2} induces synergistic cytotoxicity in HepG2 cells. ► The synergism is mainly due to forming a lipophilic ternary complex between them. ► The formation of lipophilic ternary complex enhances cellular copper uptake. ► PCP/Cu(OP){sub 2} stimulates the cellular ROS production. ► The ROS promoted by PCP/Cu(OP){sub 2} induces mitochondria-dependent apoptosis.

  11. A model of the ternary complex of interleukin-10 with its soluble receptors

    PubMed Central

    Pletnev, Sergei; Magracheva, Eugenia; Wlodawer, Alexander; Zdanov, Alexander

    2005-01-01

    Background Interleukin-10 (IL-10) is a cytokine whose main biological function is to suppress the immune response by induction of a signal(s) leading to inhibition of synthesis of a number of cytokines and their cellular receptors. Signal transduction is initiated upon formation of a ternary complex of IL-10 with two of its receptor chains, IL-10R1 and IL-10R2, expressed on the cell membrane. The affinity of IL-10R1 toward IL-10 is very high, which allowed determination of the crystal structure of IL-10 complexed with the extracellular/soluble domain of IL-10R1, while the affinity of IL-10R2 toward either IL-10 or IL-10/sIL-10R1 complex is quite low. This so far has prevented any attempts to obtain structural information about the ternary complex of IL-10 with its receptor chains. Results Structures of the second soluble receptor chain of interleukin-10 (sIL-10R2) and the ternary complex of IL-10/sIL-10R1/sIL-10R2 have been generated by homology modeling, which allowed us to identify residues involved in ligand-receptor and receptor-receptor interactions. Conclusion The previously experimentally determined structure of the intermediate/binary complex IL-10/sIL-10R1 is the same in the ternary complex. There are two binding sites for the second receptor chain on the surface of the IL-10/sIL-10R1 complex, involving both IL-10 and sIL-10R1. Most of the interactions are hydrophilic in nature, although each interface includes two internal hydrophobic clusters. The distance between C-termini of the receptor chains is 25 Å, which is common for known structures of ternary complexes of other cytokines. The structure is likely to represent the biologically active signaling complex of IL-10 with its receptor on the surface of the cell membrane. PMID:15985167

  12. The B-box dominates SAP-1-SRF interactions in the structure of the ternary complex.

    PubMed

    Hassler, M; Richmond, T J

    2001-06-15

    The serum response element (SRE) is found in several immediate-early gene promoters. This DNA sequence is necessary and sufficient for rapid transcriptional induction of the human c-fos proto-oncogene in response to stimuli external to the cell. Full activation of the SRE requires the cooperative binding of a ternary complex factor (TCF) and serum response factor (SRF) to their specific DNA sites. The X-ray structure of the human SAP-1-SRF-SRE DNA ternary complex was determined (Protein Data Bank code 1hbx). It shows SAP-1 TCF bound to SRF through interactions between the SAP-1 B-box and SRF MADS domain in addition to contacts between their respective DNA-binding motifs. The SAP-1 B-box is part of a flexible linker of which 21 amino acids become ordered upon ternary complex formation. Comparison with a similar region from the yeast MATalpha2-MCM1-DNA complex suggests a common binding motif through which MADS-box proteins may interact with additional factors such as Fli-1. PMID:11406578

  13. Translocation of Endothelial Nitric-Oxide Synthase Involves a Ternary Complex with Caveolin-1 and NOSTRIN

    PubMed Central

    Schilling, Kirstin; Opitz, Nils; Wiesenthal, Anja; Oess, Stefanie; Tikkanen, Ritva; Icking, Ann

    2006-01-01

    Recently, we characterized a novel endothelial nitric-oxide synthase (eNOS)-interacting protein, NOSTRIN (for eNOS-trafficking inducer), which decreases eNOS activity upon overexpression and induces translocation of eNOS away from the plasma membrane. Here, we show that NOSTRIN directly binds to caveolin-1, a well-established inhibitor of eNOS. Because this interaction occurs between the N terminus of caveolin (positions 1–61) and the central domain of NOSTRIN (positions 323–434), it allows for independent binding of each of the two proteins to eNOS. Consistently, we were able to demonstrate the existence of a ternary complex of NOSTRIN, eNOS, and caveolin-1 in Chinese hamster ovary (CHO)-eNOS cells. In human umbilical vein endothelial cells (HUVECs), the ternary complex assembles at the plasma membrane upon confluence or thrombin stimulation. In CHO-eNOS cells, NOSTRIN-mediated translocation of eNOS involves caveolin in a process most likely representing caveolar trafficking. Accordingly, trafficking of NOSTRIN/eNOS/caveolin is affected by altering the state of actin filaments or cholesterol levels in the plasma membrane. During caveolar trafficking, NOSTRIN functions as an adaptor to recruit mediators such as dynamin-2 essential for membrane fission. We propose that a ternary complex between NOSTRIN, caveolin-1, and eNOS mediates translocation of eNOS, with important implications for the activity and availability of eNOS in the cell. PMID:16807357

  14. Paradigms in the structural biology of the mitogenic ternary complex FGF:FGFR:heparin.

    PubMed

    Pomin, Vitor H

    2016-08-01

    The main achievements regarding the molecular interaction involving fibroblast growth factors (FGFs), canonical receptors (FGFRs) and the glycosaminoglycans (GAGs) heparan sulfate (HS)/heparin (Hp) are overviewed. Despite the recent works concerning the subject, conflicting paradigms in the structural biology of the resultant ternary complex FGF:FGFR:HS/Hp seem to persist up to these days. The principal dilemma, centered on the functional intermolecular complex of mitogenesis and angiogenesis, has been lasting for approximately a decade and a half since the publications of the two contradicting crystal structures, the asymmetric 2:2:1 versus the symmetric 2:2:2 complex model. When the principal results regarding this ternary complex are analyzed as a whole and through an impartial manner, conclusion heavily and reliably supports the existence and activity of both complex models. Selection of each complex is driven by multiple factors of different degrees of impact. Specificity in protein-binding motifs in ligands (although the minimal binding sequences are yet controversial), slight differences on the structure of the GAG-binding sites of FGF and of FGFR isoforms as well as on the possible ligand-induced conformational changes of FGFR are examples of these factors. Here, the structural biology of the mitogenic FGF:FGFR:HS/Hp ternary complex is revisited. Discussion is focused on the major attributes of this intermolecular complex including the existing conflicts about the righter biologically active model and information regarding ligand structure, conformation and minimal length required for binding to the growth factors and receptors. This review is very timely in light of the 100(th) anniversary of the discovery of Hp. PMID:27263122

  15. Reaction of N,N-diethyldithiocarbamate and other bidentate ligands with Zn, Co and Cu bovine carbonic anhydrases. Inhibition of the enzyme activity and evidence for stable ternary enzyme-metal-ligand complexes.

    PubMed

    Morpurgo, L; Desideri, A; Rigo, A; Viglino, P; Rotilio, G

    1983-08-16

    The reactions with N,N-diethyldithiocarbamate (DDC) of zinc, cobalt and copper carbonic anhydrase from bovine erythrocytes were investigated. The native zinc enzyme was inhibited by DDC, but no removal of zinc could be detected even at a very high [ligand]/[protein] ratio. At identical pH values a larger inhibitory effect was found for the cobalt enzyme. The metal was removed by DDC from the protein at pH less than 7.0. No cobalt removal occurred at pH 10, where a stable ternary complex with the enzyme-bound Co(II) was detected. Its optical and EPR spectra are indicative of five-coordinate Co(II). The reaction of the Cu(II) enzyme with stoichiometric chelating agent was marked by the appearance of an electronic transition at 390 nm (epsilon = 4300 M-1 X cm-1). Metal removal from the copper enzyme readily occurred as the ligand was in excess over the metal, with parallel appearance of a band at 440 nm, which was attributed to the free Cu(II)-DDC complex. Also, in the case of the copper enzyme an alkaline pH was found to stabilize the ternary adduct with the diagnostic 390 nm band. EPR spectra showed that the ternary adduct is a mixture of two species, both characterized by the presence in the EPR spectrum of a superhyperfine structure from two protein nitrogens and by a low g parallel value, indicative of coordination to sulfur ligands. It is suggested that the two species contain the metal as penta- and hexacoordinated, respectively. Measurements of the longitudinal relaxation time, T1, of the water protons suggested that water coordination is retained in the latter case. Hexacoordination with retention of water is also proposed for the Cu(II) derivatives with the bidentate oxalate and bicarbonate anions, unlike the corresponding Co(II) derivatives, which are pentacoordinated. Different coordination of Co(II) and Cu(II) adducts may be relevant to the difference of activity of the two substituted enzymes. PMID:6309239

  16. Physicochemical properties of ternary oxovanadium(IV) complexes with oxydiacetate and 1,10-phenanthroline or 2,2'-bipyridine. Cytoprotective activity in hippocampal neuronal HT22 cells.

    PubMed

    Wyrzykowski, Dariusz; Inkielewicz-Stępniak, Iwona; Pranczk, Joanna; Żamojć, Krzysztof; Zięba, Patrycja; Tesmar, Aleksandra; Jacewicz, Dagmara; Ossowski, Tadeusz; Chmurzyński, Lech

    2015-04-01

    The aim of this work was to find a relationship between physicochemical properties of the oxovanadium(IV) complexes, namely [VO(ODA)(H2O)2], [VO(ODA)(phen)]·1.5H2O and [VO(ODA)(bipy)]·2H2O (ODA = oxydiacetate) as well as [VO(H2O)5](2+), and their biological activity. A potentiometric titration method has been used to characterize the stability of the complexes in aqueous solutions. Furthermore, the reactivity of the complexes towards superoxide free radicals was assessed by employing the NBT assay as well as a cyclic voltammetry (CV) technique. Additionally, the investigations of the antioxidant properties of the complexes were complemented by studying their reactivity towards organic radicals (the ABTS and DPPH tests). Finally, the biological properties of the complexes were investigated in relation to their cytoprotective activity against the oxidative damage generated exogenously by using hydrogen peroxide in the Hippocampal neuronal cell line HT22 (the MTT and LDH tests). The obtained results showed that all the compounds under study display antioxidant properties but a concentration-depended protective effect against the oxidative damage was found for [VO(ODA)(bipy)]·2H2O only. PMID:25656562

  17. Synthesis, structural characterization and cytotoxic activity of ternary copper(II)-dipeptide-phenanthroline complexes. A step towards the development of new copper compounds for the treatment of cancer.

    PubMed

    Iglesias, Sebastián; Alvarez, Natalia; Torre, María H; Kremer, Eduardo; Ellena, Javier; Ribeiro, Ronny R; Barroso, Rafael P; Costa-Filho, Antonio J; Kramer, M Gabriela; Facchin, Gianella

    2014-10-01

    In the search for new compounds with antitumor activity, coordination complexes with different metals are being studied by our group. This work presents the synthesis and characterization of six copper complexes with general stoichiometry [Cu(L-dipeptide)(phen)]·nH2O (were phen=1,10-phenanthroline) and their cytotoxic activities against tumor cell lines. To characterize these systems, analytical and spectroscopic studies were performed in solid state (by UV-visible, IR, X-ray diffraction) including the crystal structure of four new complexes (of the six complexes studied): [Cu(Ala-Phe)(phen)]·4H2O, [Cu(Phe-Ala)(phen)]·4H2O, [Cu(Phe-Val)(phen)]·4.5H2O and [Cu(Phe-Phe)(phen)]·3H2O. In all of them, the copper ion is situated in a distorted squared pyramidal environment. The phen ligand is perpendicular to the dipeptide, therefore exposed and potentially available for interaction with biological molecules. In addition, for all the studied complexes, structural information in solution using EPR and UV-visible spectroscopies were obtained, showing that the coordination observed in solid state is maintained. The lipophilicity, DNA binding and albumin interaction were also studied. Biological experiments showed that all the complexes induce cell death in the cell lines: HeLa (human cervical adenocarcinoma), MCF-7 (human metastatic breast adenocarcinoma) and A549 (human lung epithelial carcinoma). Among the six complexes, [Cu(Ala-Phe)(phen)] presents the lowest IC50 values. Taken together all these data we hypothesize that [Cu(Ala-Phe)(phen)] may be a good candidate for further studies in vivo. PMID:25033418

  18. Ternary complexes of copper(II) and cobalt(II) involving nitrite/pyrazole and tetradentate N4-coordinate ligand: Synthesis, characterization, structures and antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Solanki, Ankita; Sadhu, Mehul H.; Kumar, Sujit Baran

    2015-12-01

    Five new mononuclear mixed ligand complexes of the type [Cu(NCCH3)(dbdmp)](ClO4)2, [M(ONO)(dbdmp)]ClO4, [M(pz) (dbdmp)](ClO4)2 where M = Cu(II) and Co(II), pz = 3,5-dimethylpyrazole and dbdmp = N,N-diethyl-N‧,N‧-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine have been synthesized and characterized by physico-chemical and spectroscopy studies. The crystal structures of three copper(II) complexes [Cu(NCCH3)(dbdmp)](ClO4)2, [Cu(ONO)(dbdmp)]ClO4 and [Cu(pz)(dbdmp)](ClO4)2 have been determined by single crystal X-ray diffraction studies. Structural analyses reveal the geometry of [Cu(pz)(dbdmp)](ClO4)2 is distorted square pyramidal and other two copper(II) complexes have distorted trigonal bipyramidal geometry. Molecular composition of cobalt(II) complexes have been determined by mass spectral data. The EPR spectra of copper(II) complexes in frozen acetonitrile solution exhibit axial spectra, characteristic of dx2-y2 ground state. Electrochemical studies of copper(II) complexes using glassy carbon as working electrode in acetonitrile solution show Cu(II)/Cu(I) couple with quasi reversible electron transfer versus Ag/Ag+ reference electrode. Antimicrobial activity of all the synthesized complexes were investigated against two Gram positive and two Gram negative bacterial strains.

  19. Binary and ternary copper(II) complexes of a tridentate ONS ligand derived from 2-aminochromone-3 carboxaldehyde and thiosemicarbazide: Synthesis, spectral studies and antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy; Ibrahim, M. A.; Khalil, Saied M. E.; Stefan, S. L.; Habib, H.

    2013-11-01

    A tridentate ONS donor ligand, HL, was synthesized by the condensation of 2-aminochromone-3-carboxaldehyde with thiosemicarbazide. The structure of the ligand was elucidated by elemental analyses, IR, 1H and 13C NMR, electronic and mass spectra. Reaction of the ligand with several copper(II) salts, including AcO-, NO3-, SO42-, Cl-, Br- and ClO4- afforded different metal complexes that reflect the non-coordinating or weakly coordinating power of the ClO4- and Br- anions as compared to the strongly coordinating power of AcO-, SO42-, Cl- and NO3- anions. Also, the ligand was allowed to react with Cu(II) ion in the presence of a secondary ligand (L‧) [N,O-donor; 8-hydroxyquinoline or N,N-donor; 1,10-phenanthroline]. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, electronic, mass and EPR spectra as well as conductivity and magnetic susceptibility measurements. The EPR spin Hamiltonian parameters of some complexes were calculated. The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. The ligand and most of its metal complexes showed antibacterial activity towards Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus).

  20. Electron paramagnetic resonance (EPR) study of spin-labeled camptothecin derivatives: a different look of the ternary complex.

    PubMed

    Ricci, Antonio; Marinello, Jessica; Bortolus, Marco; Sánchez, Albert; Grandas, Anna; Pedroso, Enrique; Pommier, Yves; Capranico, Giovanni; Maniero, Anna Lisa; Zagotto, Giuseppe

    2011-02-24

    Camptothecin (CPT) derivatives are clinically effective poisons of DNA topoisomerase I (Top1) able to form a ternary complex with the Top1-DNA complex. The aim of this investigation was to examine the dynamic aspects of the ternary complex formation by means of site-directed spin labeling electron paramagnetic resonance (SDSL-EPR). Two semisynthetic CPT derivatives bearing the paramagnetic moiety were synthesized, and their biological activity was tested. A 22-mer DNA oligonucleotide sequence with high affinity cleavage site for Top1 was also synthesized. EPR experiments were carried out on modified CPT in the presence of DNA, of Top1, or of both. In the last case, a slow motion component in the EPR signal appeared, indicating the formation of the ternary complex. Deconvolution of the EPR spectrum allowed to obtain the relative drug amounts in the complex. It was also possible to demonstrate that the residence time of CPT "trapped" in the ternary complex is longer than hundreds of microseconds. PMID:21254781

  1. Induction of cell death by ternary copper(II) complexes of L-tyrosine and diimines: role of coligands on DNA binding and cleavage and anticancer activity.

    PubMed

    Ramakrishnan, Sethu; Rajendiran, Venugopal; Palaniandavar, Mallayan; Periasamy, Vaiyapuri Subbarayan; Srinag, Bangalore Suresh; Krishnamurthy, Hanumanthappa; Akbarsha, Mohammad Abdulkader

    2009-02-16

    viscosity of DNA bound to 1 decreases, indicating the shortening of the DNA chain length by means of the formation of kinks or bends. All complexes exhibit effective DNA (pUC19 DNA) cleavage at 100 microM complex concentrations, and the order of DNA cleavage ability varies as 3 > 2 > 4 > 1. Interestingly, 3 exhibits a DNA cleavage rate constant that is higher than that of the other complexes only at 100 microM concentration, whereas 4 exhibits the highest cleavage rate constant at 80 microM complex concentration. The oxidative DNA cleavage follows the order 4 > 3 > 2 > 1. Mechanistic studies reveal that the DNA cleavage pathway involves hydroxyl radicals. Interestingly, only 4 displays efficient photonuclease activity upon irradiation with 365 nm light, which occurs through double-strand DNA breaks involving hydroxyl radicals. Furthermore, cytotoxicity studies on the nonsmall lung cancer (H-460) cell line show that the IC(50) values of 2-4 are more or less equal to cisplatin for the same cell line, indicating that they have the potential to act as very effective anticancer drugs in a time-dependent manner. The study of cytological changes reveals the higher induction of apoptosis and mitotic catastrophe for 4 and 3, respectively. The alkaline single-cell gel electrophoresis (comet assay), DNA laddering, and AO/EB and Hoechst 33258 staining assays have also been employed in finding the extent of DNA damage. Flow cytometry analysis shows an increase in the percentage of cells with apoptotic morphological features in the sub-G(0)/G(1) phase for 4, whereas it shows mitotic catastrophe for 3. PMID:19140687

  2. 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

  3. Cholesteryl ester transfer between lipoproteins does not require a ternary tunnel complex with CETP.

    PubMed

    Lauer, Matthias E; Graff-Meyer, Alexandra; Rufer, Arne C; Maugeais, Cyrille; von der Mark, Elisabeth; Matile, Hugues; D'Arcy, Brigitte; Magg, Christine; Ringler, Philippe; Müller, Shirley A; Scherer, Sebastian; Dernick, Gregor; Thoma, Ralf; Hennig, Michael; Niesor, Eric J; Stahlberg, Henning

    2016-05-01

    The cholesteryl ester transfer protein (CETP) enables the transfer of cholesteryl ester (CE) from high-density lipoproteins (HDL) to low-density lipoproteins (LDL) in the plasma compartment. CETP inhibition raises plasma levels of HDL cholesterol; a ternary tunnel complex with CETP bridging HDL and LDL was suggested as a mechanism. Here, we test whether the inhibition of CETP tunnel complex formation is a promising approach to suppress CE transfer from HDL to LDL, for potential treatment of cardio-vascular disease (CVD). Three monoclonal antibodies against different epitopes of CETP are assayed for their potential to interfere with CE transfer between HDL and/or LDL. Surprisingly, antibodies that target the tips of the elongated CETP molecule, interaction sites sterically required to form the suggested transfer complexes, do not interfere with CETP activity, but an antibody binding to the central region does. We show that CETP interacts with HDL, but not with LDL. Our findings demonstrate that a ternary tunnel complex is not the mechanistic prerequisite to transfer CE among lipoproteins. PMID:26876146

  4. The ternary complex factor Net regulates cell migration through inhibition of PAI-1 expression.

    PubMed

    Buchwalter, Gilles; Gross, Christian; Wasylyk, Bohdan

    2005-12-01

    Net, Elk-1, and Sap-1 are members of the ternary complex factor (TCF) subfamily of Ets transcription factors. They form ternary complexes with serum response factor (SRF) on serum response elements of immediate early genes such as c-fos and egr-1 and mediate responses to growth factors and mitogen-activated protein kinase signaling. Although the TCFs have been extensively studied as intermediates in signaling cascades, surprisingly little is known about their different target genes and physiological functions. We report that Net homozygous mutant mouse embryonic fibroblasts have a defect in cell migration. This defect results at least in part from increased expression of plasminogen activator inhibitor type 1 (PAI-1), a serine protease inhibitor (serpin) that controls extracellular proteolysis and cell matrix adhesion. The defect in cell migration can be reverted by the addition of a PAI-1 blocking antibody. Net represses PAI-1 promoter activity and binds to a specific region of the promoter containing Ets binding sites in the absence of SRF. We conclude that Net is a negative regulator of PAI-1 expression and is thereby involved in cell migration. PMID:16314510

  5. PGAM5 tethers a ternary complex containing Keap1 and Nrf2 to mitochondria

    SciTech Connect

    Lo, S.-C.; Hannink, Mark

    2008-05-01

    Eukaryote cells balance production of reactive oxygen species (ROS) with levels of anti-oxidant enzyme activity to maintain cellular redox homeostasis. Mitochondria are a major source of ROS, while many anti-oxidant genes are regulated by the Nrf2 transcription factor. Keap1, a redox-regulated substrate adaptor for a cullin-based ubiquitin ligase, targets Nrf2 for proteosome-mediated degradation and represses Nrf2-dependent gene expression. We have previously identified a member of the phosphoglycerate mutase family, PGAM5, as a Keap1-binding protein. In this report, we demonstrate that PGAM5 is targeted to the outer membrane of mitochondria by an N-terminal mitochondrial-localization sequence. Furthermore, we provide evidence that PGAM5 forms a ternary complex containing both Keap1 and Nrf2, in which the dimeric Keap1 protein simultaneously binds both PGAM5 and Nrf2 through their conserved E(S/T)GE motifs. Knockdown of either Keap1 or PGAM5 activates Nrf2-dependent gene expression. We suggest that this ternary complex provides a molecular framework for understanding how nuclear anti-oxidant gene expression is regulated in response to changes in mitochondrial function(s)

  6. Comparative analysis of the ternary complex factors Elk-1, SAP-1a and SAP-2 (ERP/NET).

    PubMed

    Price, M A; Rogers, A E; Treisman, R

    1995-06-01

    A transcription factor ternary complex composed of Serum Response Factor (SRF) and Ternary Complex Factor (TCF) mediates the response of the c-fos Serum Response Element (SRE) to growth factors and mitogens. Three Ets domain proteins, Elk-1, SAP-1 and ERP/NET, have been reported to have the properties of TCF. Here we compare Elk-1 and SAP-1a with the human ERP/NET homologue SAP-2. All three TCF RNAs are ubiquitously expressed at similar relative levels. All three proteins contain conserved regions that interact with SRF and the c-fos SRE with comparable efficiency, but in vitro complex formation by SAP-2 is strongly inhibited by its C-terminal sequences. Similarly, only Elk-1 and SAP-1a efficiently bind the c-fos SRE in vivo; ternary complex formation by SAP-2 is weak and is substantially unaffected by serum stimulation or v-ras co-expression. All three TCFs contain C-terminal transcriptional activation domains that are phosphorylated following growth factor stimulation. Activation requires conserved S/T-P motifs found in all the TCF family members. Each TCF activation domain can be phosphorylated in vitro by partially purified ERK2, and ERK activation in vivo is sufficient to potentiate transcriptional activation. PMID:7540136

  7. Crystallization, data collection and processing of the chymotrypsin–BTCI–trypsin ternary complex

    SciTech Connect

    Esteves, Gisele Ferreira; Teles, Rozeni Chagas Lima; Cavalcante, Nayara Silva; Neves, David; Ventura, Manuel Mateus; Barbosa, João Alexandre Ribeiro Gonçalves; Freitas, Sonia Maria de

    2007-12-01

    A ternary complex of the proteinase inhibitor (BTCI) with trypsin and chymotrypsin was crystallized and its crystal structure was solved by molecular replacement. A ternary complex of the black-eyed pea trypsin and chymotrypsin inhibitor (BTCI) with trypsin and chymotrypsin was crystallized by the sitting-drop vapour-diffusion method with 0.1 M HEPES pH 7.5, 10%(w/v) polyethylene glycol 6000 and 5%(v/v) 2-methyl-2,4-pentanediol as precipitant. BTCI is a small protein with 83 amino-acid residues isolated from Vigna unguiculata seeds and is able to inhibit trypsin and chymotrypsin simultaneously by forming a stable ternary complex. X-ray data were collected from a single crystal of the trypsin–BTCI–chymotrypsin ternary complex to 2.7 Å resolution under cryogenic conditions. The structure of the ternary complex was solved by molecular replacement using the crystal structures of the BTCI–trypsin binary complex (PDB code) and chymotrypsin (PDB code) as search models.

  8. Optical, Thermal Studies on Binary and Ternary Hydrogen-Bonded Liquid Crystal Complexes

    NASA Astrophysics Data System (ADS)

    Mahalingam, T.; Venkatachalam, T.; Jayaprakasam, R.; Vijayakumar, V. N.

    2016-06-01

    Hydrogen-bonded ferroelectric liquid crystalline (HBFLC) complexes are synthesized from binary mixtures of l-(+)-tartaric acid with 4-dodecyloxybenzoic acid and cholesteryl acetate. A ternary complex has been obtained from l-(+)-tartaric acid, 4-dodecyloxybenzoic acid, and cholesteryl acetate. Fourier transform infrared spectroscopy (FTIR) studies confirm the formation of an intermolecular hydrogen bond in the binary as well as the ternary complex. The l-(+)-tartaric acid does not show any mesomorphic behavior, but the hydrogen-bonded binary and ternary complexes are exhibiting the nematic phase along with tilted smectic phases. Phase transition properties of HBFLC mixtures have been investigated by means of differential scanning calorimetry (DSC) and polarizing optical microscope (POM). The DSC and POM clearly reveal the existence of nematic and smectic phases in the HBFLC mixtures. The optical tilt angle of binary and ternary mixtures for smectic C* phase and thermal stability factors of the mesogenic phases have been discussed. The noteworthy observation is that there is a significant reduction of phase transition temperatures with enhanced phase width, lowering melting temperature, and clearing point in the HBFLC ternary complex.

  9. 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. PMID:26697780

  10. Ternary copper complexes and manganese (III) tetrakis(4-benzoic acid) porphyrin catalyze peroxynitrite-dependent nitration of aromatics.

    PubMed

    Ferrer-Sueta, G; Ruiz-Ramírez, L; Radi, R

    1997-12-01

    Peroxynitrite is a powerful oxidant formed in biological systems from the reaction of nitrogen monoxide and superoxide and is capable of nitrating phenols at neutral pH and ambient temperature. This peroxynitrite-mediated nitration is catalyzed by a number of Lewis acids, including CO2 and transition-metal ion complexes. Here we studied the effect of ternary copper-(II) complexes constituted by a 1,10-phenanthroline and an amino acid as ligands. All the complexes studied accelerate both the decomposition of peroxynitrite and its nitration of 4-hydroxyphenylacetic acid at pH > 7. The rate of these reactions depends on the copper complex concentration in a hyperbolic plus linear manner. The yield of nitrated products increases up to 2.6-fold with respect to proton-catalyzed nitration and has a dependency on the concentration of copper complexes which follows the same function as observed for the rate constants. The manganese porphyrin complex, Mn(III)tetrakis(4-benzoic acid)porphyrin [Mn(tbap)], also promoted peroxynitrite-mediated nitration with an even higher yield (4-fold increase) than the ternary copper complexes. At pH = 7.5 +/- 0.2 the catalytic behavior of the copper complexes can be linearly correlated with the pKa of the phenanthroline present as a ligand, implying that a peroxynitrite anion is coordinated to the copper ion prior to the nitration reaction. These observations may prove valuable to understand the biological effects of these transition-metal complexes (i.e., copper and manganese) that can mimic superoxide dismutase activity and, in the case of the ternary copper complexes, show antineoplastic activity. PMID:9437523

  11. 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.

  12. Molecular Dynamics of Rab7::REP1::GGTase-II Ternary Complex and Identification of Their Putative Drug Binding Sites.

    PubMed

    Sindhu, Meenakshi; Saini, Vandana; Piplani, Sakshi; Kumar, A

    2013-01-01

    The structure-function correlation of membrane proteins have been a difficult task, particularly in context to transient protein complexes. The molecular simulation of ternary complex of Rab7::REP1::GGTase-II was carried out to understand the basic structural events occurring during the prenylation event of Rab proteins, using the software YASARA. The study suggested that the C-terminus of Rab7 has to be in completely extended conformation during prenylation to reach the active site of RabGGTase-II. Also, attempt was made to find putative drug binding sites on the ternary complex of Rab7::REP1::GGTase-II using Q-SiteFinder programme. The comprehensive consensus probe generated by the program revealed a total of 10 major pockets as putative drug binding sites on Rab7::REP:: GGTase-II ternary complex. These pockets were found on REP protein and GGTase protein subunits. The Rab7 was found to be devoid of any putative drug binding sites in the ternary complex. The phylogenetic analysis of 60 Rab proteins of human was carried out using PHYLIP and study indicated the close phylogenetic relationship between Rab7 and Rab9 proteins of human and hence with further in silico study, the present observations can be extrapolated to Rab9 proteins. The study paves a good platform for further experimental verifications of the findings and other in silico studies like identifying the potential drug targets by searching the putative drug binding sites, generating pharmacophoric pattern, searching or constructing suitable ligand and docking studies. PMID:23901157

  13. Ternary dendritic nanowires as highly active and stable multifunctional electrocatalysts.

    PubMed

    Yang, Yoojin; Jin, Haneul; Kim, Ho Young; Yoon, Jisun; Park, Jongsik; Baik, Hionsuck; Joo, Sang Hoon; Lee, Kwangyeol

    2016-08-18

    Multimetallic nanocatalysts with a controlled structure can provide enhanced catalytic activity and durability by exploiting electronic, geometric, and strain effects. Herein, we report the synthesis of a novel ternary nanocatalyst based on Mo doped PtNi dendritic nanowires (Mo-PtNi DNW) and its bifunctional application in the methanol oxidation reaction (MOR) at the anode and the oxygen reduction reaction (ORR) at the cathode for direct methanol fuel cells. An unprecedented Mo-PtNi DNW structure can combine multiple structural attributes of the 1D nanowire morphology and dendritic surfaces. In the MOR, Mo-PtNi DNW exhibits superior activity to Pt/C and Mo doped Pt dendritic nanowires (Mo-Pt DNW), and excellent durability. Furthermore, Mo-PtNi DNW demonstrates excellent activity and durability for the ORR. This work highlights the important role of compositional and structural control in nanocatalysts for boosting catalytic performances. PMID:27507777

  14. 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. PMID:25555321

  15. PHOTODEGRADATION OF A TERNARY IRON(III)-URANIUM(VI)-CITRIC ACID COMPLEX

    EPA Science Inventory

    The mechanisms of photodegradation of binary iron- and uranium-citrate and ternary iron-uranium-citrate complexes were elucidated. Citric acid degradation products were identified by HPLC and GC, and the metal precipitates were identified by XRD and EXAFS. Photodegradation of a b...

  16. Triethanolamine Stabilization of Methotrexate-β-Cyclodextrin Interactions in Ternary Complexes

    PubMed Central

    Barbosa, Jahamunna A. A.; Zoppi, Ariana; Quevedo, Mario A.; de Melo, Polyanne N.; de Medeiros, Arthur S. A.; Streck, Letícia; de Oliveira, Alice R.; Fernandes-Pedrosa, Matheus F.; Longhi, Marcela R.; da Silva-Júnior, Arnóbio A.

    2014-01-01

    The interaction of methotrexate (MTX) with beta-cyclodextrin (β-CD) in the presence of triethanolamine (TEA) was investigated with the aim to elucidate the mechanism whereby self-assembly cyclodextrin systems work in association with this third component. Solubility diagram studies showed synergic increment of the MTX solubility to be about thirty-fold. Experiments using 2D ROESY and molecular modeling studies revealed the inclusion of aromatic ring III of the drug into β-CD cavity, in which TEA contributes by intensifying MTX interaction with β-CD and stabilizes MTX:β-CD:TEA ternary complex by electrostatic interaction. The maintenance of these interactions in solid phase was also studied in ternary MTX:β-CD:TEA and comparisons were made with freeze dried binary MTX:β-CD and physical mixtures. FTIR studies evidenced that MTX–β-CD interaction remained in solid ternary complexes, which was also supported by thermal (differential scanning calorimetry (DSC), thermogravimetric analysis (TG)/first derivative of TG analysis (DTG) and C,N,H elementary analysis) and structural (X-ray diffraction analysis, (XRD)) studies, mainly regarding the increment of drug stability. The efficient in vitro drug dissolution studies successfully demonstrated the contribution of ternary complexes, which highlights the importance of this possible new raw material for further applications in drug delivery systems. PMID:25257529

  17. Triethanolamine stabilization of methotrexate-β-cyclodextrin interactions in ternary complexes.

    PubMed

    Barbosa, Jahamunna A A; Zoppi, Ariana; Quevedo, Mario A; de Melo, Polyanne N; de Medeiros, Arthur S A; Streck, Letícia; de Oliveira, Alice R; Fernandes-Pedrosa, Matheus F; Longhi, Marcela R; da Silva-Júnior, Arnóbio A

    2014-01-01

    The interaction of methotrexate (MTX) with beta-cyclodextrin (β-CD) in the presence of triethanolamine (TEA) was investigated with the aim to elucidate the mechanism whereby self-assembly cyclodextrin systems work in association with this third component. Solubility diagram studies showed synergic increment of the MTX solubility to be about thirty-fold. Experiments using 2D ROESY and molecular modeling studies revealed the inclusion of aromatic ring III of the drug into β-CD cavity, in which TEA contributes by intensifying MTX interaction with β-CD and stabilizes MTX:β-CD:TEA ternary complex by electrostatic interaction. The maintenance of these interactions in solid phase was also studied in ternary MTX:β-CD:TEA and comparisons were made with freeze dried binary MTX:β-CD and physical mixtures. FTIR studies evidenced that MTX-β-CD interaction remained in solid ternary complexes, which was also supported by thermal (differential scanning calorimetry (DSC), thermogravimetric analysis (TG)/first derivative of TG analysis (DTG) and C,N,H elementary analysis) and structural (X-ray diffraction analysis, (XRD)) studies, mainly regarding the increment of drug stability. The efficient in vitro drug dissolution studies successfully demonstrated the contribution of ternary complexes, which highlights the importance of this possible new raw material for further applications in drug delivery systems. PMID:25257529

  18. 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. PMID:27474600

  19. The ternary complex of PrnB (the second enzyme in the pyrrolnitrin biosynthesis pathway), tryptophan, and cyanide yields new mechanistic insights into the indolamine dioxygenase superfamily.

    PubMed

    Zhu, Xiaofeng; van Pée, Karl-Heinz; Naismith, James H

    2010-07-01

    Pyrrolnitrin (3-chloro-4-(2'-nitro-3'-chlorophenyl)pyrrole) is a broad-spectrum antifungal compound isolated from Pseudomonas pyrrocinia. Four enzymes (PrnA, PrnB, PrnC, and PrnD) are required for pyrrolnitrin biosynthesis from tryptophan. PrnB rearranges the indole ring of 7-Cl-l-tryptophan and eliminates the carboxylate group. PrnB shows robust activity in vivo, but in vitro activity for PrnB under defined conditions remains undetected. The structure of PrnB establishes that the enzyme belongs to the heme b-dependent indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO) family. We report the cyanide complex of PrnB and two ternary complexes with both l-tryptophan or 7-Cl-l-tryptophan and cyanide. The latter two complexes are essentially identical and mimic the likely catalytic ternary complex that occurs during turnover. In the cyanide ternary complexes, a loop previously disordered becomes ordered, contributing to the binding of substrates. The conformations of the bound tryptophan substrates are changed from that seen previously in the binary complexes. In l-tryptophan ternary complex, the indole ring now adopts the same orientation as seen in the PrnB binary complexes with other tryptophan substrates. The amide and carboxylate group of the substrate are orientated in a new conformation. Tyr(321) and Ser(332) play a key role in binding these groups. The structures suggest that catalysis requires an l-configured substrate. Isothermal titration calorimetry data suggest d-tryptophan does not bind after cyanide (or oxygen) coordinates with the distal (or sixth) site of heme. This is the first ternary complex with a tryptophan substrate of a member of the tryptophan dioxygenase superfamily and has mechanistic implications. PMID:20421301

  20. Spectrophotometric and AAS determination of ramipril and enalapril through ternary complex formation.

    PubMed

    Ayad, Magda M; Shalaby, Abdalla A; Abdellatef, Hisham E; Hosny, Mervat M

    2002-04-15

    Two sensitive, spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of two antihypertensive agents (enalapril maleate and ramipril). The spectrophotometric procedures for the two cited drugs are based on ternary complex formation. The first ternary complex (copper(II), eosin, and enalapril) was estimated by two methods; the first depends on its extraction with chloroform measuring at 533.4 nm. Beer's law was obeyed in concentration range from 56 to 112 microg ml(-1). The second method for the same complex depends on its direct measurement after addition of methylcellulose as surfactant at the pH value 5 at 558.8 nm. The concentration range is from 19 to 32 microg ml(-1). The second ternary complex (iron(III), thiocyanate, and ramipril) was extracted with methylene chloride, measuring at 436.6 nm, with a concentration range 60-132 microg ml(-1). The direct atomic absorption spectrometric method through the quantitative determination of copper or iron content of the complex was also investigated for the purpose of enhancing the sensitivity of the determination. The spectrophotometric and atomic absorption spectrometric procedures hold their accuracy and precision well when applied to the determination of ramipril and enalapril dosage forms. PMID:11929674

  1. Self-assembled ternary complexes stabilized with hyaluronic acid-green tea catechin conjugates for targeted gene delivery.

    PubMed

    Liang, Kun; Bae, Ki Hyun; Lee, Fan; Xu, Keming; Chung, Joo Eun; Gao, Shu Jun; Kurisawa, Motoichi

    2016-03-28

    Nanosized polyelectrolyte complexes are attractive delivery vehicles for the transfer of therapeutic genes to diseased cells. Here we report the application of self-assembled ternary complexes constructed with plasmid DNA, branched polyethylenimine and hyaluronic acid-green tea catechin conjugates for targeted gene delivery. These conjugates not only stabilize plasmid DNA/polyethylenimine complexes via the strong DNA-binding affinity of green tea catechin, but also facilitate their transport into CD44-overexpressing cells via receptor-mediated endocytosis. The hydrodynamic size, surface charge and physical stability of the complexes are characterized. We demonstrate that the stabilized ternary complexes display enhanced resistance to nuclease attack and polyanion-induced dissociation. Moreover, the ternary complexes can efficiently transfect the difficult-to-transfect HCT-116 colon cancer cell line even in serum-supplemented media due to their enhanced stability and CD44-targeting ability. Confocal microscopic analysis demonstrates that the stabilized ternary complexes are able to promote the nuclear transport of plasmid DNA more effectively than binary complexes and hyaluronic acid-coated ternary complexes. The present study suggests that the ternary complexes stabilized with hyaluronic acid-green tea catechin conjugates can be widely utilized for CD44-targeted delivery of nucleic acid-based therapeutics. PMID:26855049

  2. Effectiveness, against tuberculosis, of pseudo-ternary complexes: peptide-DNA-cationic liposome.

    PubMed

    Rosada, Rogério Silva; Silva, Célio Lopes; Santana, Maria Helena Andrade; Nakaie, Clóvis Ryuichi; de la Torre, Lucimara Gaziola

    2012-05-01

    We report the effects of a synthetic peptide designed to act as a nuclear localization signal on the treatment of tuberculosis. The peptide contains 21 amino acid residues with the following specific domains: nuclear localization signal from SV 40T, cationic shuttle sequence, and cysteamide group at the C-terminus. The peptide was complexed with the plasmid DNAhsp65 and incorporated into cationic liposomes, forming a pseudo-ternary complex. The same cationic liposomes, composed of egg chicken L-α-phosphatidylcholine, 1,2-dioleoyl-3-trimethylammonium-propane, and 1,2-dioleoyl-3-trimethylammonium-propane (2:1:1M), were previously evaluated as a gene carrier for tuberculosis immunization protocols with DNAhsp65. The pseudo-ternary complex presented a controlled size (250 nm), spherical-like shape, and various lamellae in liposomes as evaluated by transmission electron microscopy. An assay of fluorescence probe accessibility confirmed insertion of the peptide/DNA into the liposome structure. Peptide addition conferred no cytotoxicity in vitro, and similar therapeutic effects against tuberculosis were seen with four times less DNA compared with naked DNA treatment. Taken together, the results indicate that the pseudo-ternary complex is a promising gene vaccine for tuberculosis treatment. This work contributes to the development of multifunctional nanostructures in the search for strategies for in vivo DNA delivery. PMID:21999959

  3. Neuronal nitric-oxide synthase localization mediated by a ternary complex with synapsin and CAPON

    PubMed Central

    Jaffrey, Samie R.; Benfenati, Fabio; Snowman, Adele M.; Czernik, Andrew J.; Snyder, Solomon H.

    2002-01-01

    The specificity of the reactions of nitric oxide (NO) with its neuronal targets is determined in part by the precise localizations of neuronal NO synthase (nNOS) within the cell. The targeting of nNOS is mediated by adapter proteins that interact with its PDZ domain. Here, we show that the nNOS adapter protein, CAPON, interacts with synapsins I, II, and III through an N-terminal phosphotyrosine-binding domain interaction, which leads to a ternary complex comprising nNOS, CAPON, and synapsin I. The significance of this ternary complex is demonstrated by changes in subcellular localization of nNOS in mice harboring genomic deletions of both synapsin I and synapsin II. These results suggest a mechanism for specific actions of NO at presynaptic sites. PMID:11867766

  4. A topological model for transcription based on unwinding angle analysis of E. coli RNA polymerase binary, initiation and ternary complexes.

    PubMed

    Gamper, H B; Hearst, J E

    1982-05-01

    DNA unwinding induced by Escherichia coli RNA polymerase is measured for binary, initiation and ternary complexes formed from a unique promoter sequence on simian virus 40 DNA. At 37 degrees C the complexes all have an unwinding angle of 17 +/- 1 base pairs (580 degrees +/- 30 degrees). This unwinding is attributed to an enzyme-stabilized separation of the double helix at the promoter site, which is maintained throughout initiation and elongation. There is no heterogeneity in the unwinding angle of the ternary complex as it progresses down the helical template. The constant DNA unwinding during all phases of transcription leads us to propose the existence of unwindase and rewindase activities on the enzyme that allow it to travel down the helix like a nut on a DNA bolt. During elongation, the unwindase unwinds the DNA helix while the rewindase, lagging by 17 base pairs, displaces the RNA transcript and reseals the helix. Both activities induce a rotation in the DNA double helix relative to the polymerase. The RNA-DNA hybrid also rotates, maintaining both ends of that helix fixed relative to the catalytic and windase sites. Formation of an RNA-DNA hybrid which spans the distal end of the DNA unwound region is proposed as a possible mechanism for polymerase pausing and termination. This model requires that the polymerase direct the transcript past the noncoding DNA strand. Pausing occurs 16-20 nucleotides downstream from the centers of appropriately sized dyad symmetry elements. PMID:6286146

  5. Ternary complexation of carvedilol, beta-cyclodextrin and citric acid for mouth-dissolving tablet formulation.

    PubMed

    Pokharkar, Varsha; Khanna, Abhishek; Venkatpurwar, Vinod; Dhar, Sheetal; Mandpe, Leenata

    2009-06-01

    The purpose of this study was to improve the solubility and dissolution rate of carvedilol by forming a ternary complex with beta-cyclodextrin and citric acid and to formulate its mouth-dissolving tablets. The rationale for preparing mouth-dissolving tablet of carvedilol was to make the drug available in a soluble form in the mouth, which would facilitate its absorption from the buccal cavity. This would help to overcome its first-pass metabolism and thereby improve bioavailability. Phase solubility studies revealed the ability of beta-cyclodextrin and citric acid to complex with carvedilol and significantly increase its solubility. Ternary complexation of carvedilol was carried out with beta-cyclodextrin and citric acid by physical mixing, kneading and spray drying methods and the prepared complexes were characterized by Fourier transform infra red spectroscopy, differential scanning calorimetry, powder X-ray diffractometry, scanning electron microscopy and complexation efficiency. The complex obtained by the spray drying method resulted in highest complexation efficiency and a 110-fold increase in the solubility of carvedilol. The mouth-dissolving tablets formulated using the spray dried complex with suitable excipients showed 100 % dissolution within five minutes. Accelerated stability studies of mouth-dissolving tablets carried out as per ICH guidelines revealed that the tablets were stable. PMID:19564138

  6. Growth inhibitory effect of the ternary complex factor Net on human pancreatic carcinoma cell lines.

    PubMed

    Li, Baiwen; Ni, Peihua; Zhu, Qi; Cao, Haixia; Xu, Hong; Zhang, Su; Au, Chris; Zhang, Yongping

    2008-10-01

    Pancreatic carcinoma is one of the most aggressive malignancies and carries the most dismal prognoses of all cancers. A better understanding of the genes involving in tumor development may allow us to tackle this rapidly progressive disease. The Net gene belongs to the ternary complex transcription factor (TCF) family and is regulated by the Ras/mitogen-activated protein kinase-signaling pathway. Under basal conditions, Net shows strong repressing function on transcription of proto-oncogene gene c-fos. Moreover, the lower expression of Net has been noted in some carcinoma cells, such as cervical cancer. To study the effect of Net on c-fos expression and its potential role in the growth of pancreatic carcinoma, we developed a recombinant plasmid, a pEGFP-N1-Net, which codes for Net-EGFP fusion proteins, and stably transfected it into BxPC-3 human pancreatic carcinoma cells. Using stable transformants, we were able to show that overexpression of Net decreased the expression of c-fos and inhibited pancreatic cancer cell proliferation. Cell cycle analysis demonstrated that Net overexpression inhibited cell cycle progression. These findings suggested that loss of Net repression could augment c-fos expression and further trigger neoplastic cell proliferation, which was involved in the pathogenesis of pancreatic cancer. Therefore, Net might be a potential target for the treatment of c-fos-positive pancreatic cancer. PMID:18832796

  7. Structure of the Human Rev1-DNA-dNTP Ternary Complex

    SciTech Connect

    Swan, M.; Johnson, R; Prakash, L; Prakash, S; Aggarwal, A

    2009-01-01

    Y-family DNA polymerases have proven to be remarkably diverse in their functions and in strategies for replicating through DNA lesions. The structure of yeast Rev1 ternary complex has revealed the most radical replication strategy, where the polymerase itself dictates the identity of the incoming nucleotide, as well as the identity of the templating base. We show here that many of the key elements of this highly unusual strategy are conserved between yeast and human Rev1, including the eviction of template G from the DNA helix and the pairing of incoming deoxycytidine 5'-triphosphate with a surrogate arginine residue. We also show that the catalytic core of human Rev1 is uniquely augmented by two large inserts, I1 and I2, wherein I1 extends > 20 A away from the active site and may serve as a platform for protein-protein interactions specific for Rev1's role in translesion DNA synthesis in human cells, and I2 acts as a 'flap' on the hydrophobic pocket accommodating template G. We suggest that these novel structural features are important for providing human Rev1 greater latitude in promoting efficient and error-free translesion DNA synthesis through the diverse array of bulky and potentially carcinogenic N2-deoxyguanosine DNA adducts in human cells.

  8. Crystal structure of a nuclear actin ternary complex.

    PubMed

    Cao, Tingting; Sun, Lingfei; Jiang, Yuxiang; Huang, Shanjin; Wang, Jiawei; Chen, Zhucheng

    2016-08-01

    Actin polymerizes and forms filamentous structures (F-actin) in the cytoplasm of eukaryotic cells. It also exists in the nucleus and regulates various nucleic acid transactions, particularly through its incorporation into multiple chromatin-remodeling complexes. However, the specific structure of actin and the mechanisms that regulate its polymeric nature inside the nucleus remain unknown. Here, we report the crystal structure of nuclear actin (N-actin) complexed with actin-related protein 4 (Arp4) and the helicase-SANT-associated (HSA) domain of the chromatin remodeler Swr1. The inner face and barbed end of N-actin are sequestered by interactions with Arp4 and the HSA domain, respectively, which prevents N-actin from polymerization and binding to many actin regulators. The two major domains of N-actin are more twisted than those of globular actin (G-actin), and its nucleotide-binding pocket is occluded, freeing N-actin from binding to and regulation by ATP. These findings revealed the salient structural features of N-actin that distinguish it from its cytoplasmic counterpart and provide a rational basis for its functions and regulation inside the nucleus. PMID:27457955

  9. Novel siRNA delivery system using a ternary polymer complex with strong silencing effect and no cytotoxicity.

    PubMed

    Kodama, Yukinobu; Shiokawa, Yumi; Nakamura, Tadahiro; Kurosaki, Tomoaki; Aki, Keisei; Nakagawa, Hiroo; Muro, Takahiro; Kitahara, Takashi; Higuchi, Norihide; Sasaki, Hitoshi

    2014-01-01

    We developed a novel small interfering RNA (siRNA) delivery system using a ternary complex with polyethyleneimine (PEI) and γ-polyglutamic acid (γ-PGA), which showed silencing effect and no cytotoxicity. The binary complexes of siRNA with PEI were approximately 73-102 nm in particle size and 45-52 mV in ζ-potential. The silencing effect of siRNA/PEI complexes increased with an increase of PEI, and siRNA/PEI complexes with a charge ratio greater than 16 showed significant luciferase knockdown in a mouse colon carcinoma cell line regularly expressing luciferase (Colon26/Luc cells). However, strong cytotoxicity and blood agglutination were observed in the siRNA/Lipofectamine complex and siRNA/PEI16 complex. Recharging cationic complexes with an anionic compound was reported to be a promising method for overcoming these toxicities. We therefore prepared ternary complexes of siRNA with PEI (charge ratio 16) by the addition of γ-PGA to reduce cytotoxicity and deliver siRNA. As expected, the cytotoxicity of the ternary complexes decreased with an increase of γ-PGA content, which decreased the ζ-potential of the complexes. A strong silencing effect comparable to siRNA/Lipofectamine complex was discovered in ternary complexes including γ-PGA with an anionic surface charge. The high incorporation of ternary complexes into Colon26/Luc cells was confirmed with fluorescence microcopy. Having achieved knockdown of an exogenously transfected gene, the ability of the complex to mediate knockdown of an endogenous housekeeping gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), was assessed in B16-F10 cells. The ternary complex (siRNA/PEI16/γ-PGA12 complex) exhibited a significant GAPDH knockdown effect. Thus, we developed a useful siRNA delivery system. PMID:25087949

  10. Serum Response Factor-GATA Ternary Complex Required for Nuclear Signaling by a G-Protein-Coupled Receptor

    PubMed Central

    Morin, Steves; Paradis, Pierre; Aries, Anne; Nemer, Mona

    2001-01-01

    Endothelins are a family of biologically active peptides that are critical for development and function of neural crest-derived and cardiovascular cells. These effects are mediated by two G-protein-coupled receptors and involve transcriptional regulation of growth-responsive and/or tissue-specific genes. We have used the cardiac ANF promoter, which represents the best-studied tissue-specific endothelin target, to elucidate the nuclear pathways responsible for the transcriptional effects of endothelins. We found that cardiac-specific response to endothelin 1 (ET-1) requires the combined action of the serum response factor (SRF) and the tissue-restricted GATA proteins which bind over their adjacent sites, within a 30-bp ET-1 response element. We show that SRF and GATA proteins form a novel ternary complex reminiscent of the well-characterized SRF-ternary complex factor interaction required for transcriptional induction of c-fos in response to growth factors. In transient cotransfections, GATA factors and SRF synergistically activate atrial natriuretic factor and other ET-1-inducible promoters that contain both GATA and SRF binding sites. Thus, GATA factors may represent a new class of tissue-specific SRF accessory factors that account for muscle- and other cell-specific SRF actions. PMID:11158291

  11. Identification of a ternary protein-complex as a therapeutic target for K-Ras-dependent colon cancer

    PubMed Central

    Hou, Songwang; Li, Gang; Yin, Ning; Dong, Lei; Lepp, Adrienne; Chesnik, Marla A.; Mirza, Shama P.; Szabo, Aniko; Tsai, Susan; Basir, Zainab; Wu, Shixiu; Chen, Guan

    2014-01-01

    A cancer phenotype is driven by several proteins and targeting a cluster of functionally interdependent molecules should be more effective for therapeutic intervention. This is specifically important for Ras-dependent cancer, as mutated (MT) Ras is non-druggable and targeting its interaction with effectors may be essential for therapeutic intervention. Here, we report that a protein-complex activated by the Ras effector p38γ MAPK is a novel therapeutic target for K-Ras-dependent colon cancer. Unbiased proteomic screening and immune-precipitation analyses identified p38γ interaction with heat shock protein 90 (Hsp90) and K-Ras in K-Ras MT, but not wild-type (WT), colon cancer cells, indicating a role of this complex in Ras-dependent growth. Further experiments showed that this complex requires p38γ and Hsp90 activity to maintain MT, but not WT, K-Ras protein expression. Additional studies demonstrated that this complex is activated by p38γ-induced Hsp90 phosphorylation at S595, which is important for MT K-Ras stability and for K-Ras dependent growth. Of most important, pharmacologically inhibition of Hsp90 or p38γ activity disrupts the complex, decreases K-Ras expression, and selectively inhibits the growth of K-Ras MT colon cancer in vitro and in vivo. These results demonstrated that the p38γ-activated ternary complex is a novel therapeutic target for K-Ras-dependent colon cancer. PMID:24962213

  12. Nuclear receptors modulate the interaction of Sp1 and GC-rich DNA via ternary complex formation.

    PubMed Central

    Husmann, M; Dragneva, Y; Romahn, E; Jehnichen, P

    2000-01-01

    Binding sites for transcription factor Sp1 have been implicated in the transcriptional regulation of several genes by hormones or vitamins, and here we show that a GC-rich element contributes to the retinoic acid response of the interleukin 1beta promoter. To explain such observations, it has been proposed that nuclear receptors can interact with Sp1 bound to GC-rich DNA. However, evidence supporting this model has remained indirect. So far, nuclear receptors have not been detected in a complex with Sp1 and GC-rich DNA, and the expected ternary complexes in non-denaturing gels were not seen. In search for these missing links we found that nuclear receptors [retinoic acid receptor (RAR), thyroid hormone receptor (TR), vitamin D(3) receptor, peroxisome-proliferator-activated receptor and retinoic X receptor] induce an electrophoretic mobility increase of Sp1-GC-rich DNA complexes. Concomitantly, binding of Sp1 to the GC-box is enhanced. It is proposed that nuclear receptors may partially replace Sp1 in homo-oligomers at the GC-box. RARs and Sp1 can also combine into a complex with a retinoic acid-response element. The presence of RAR and Sp1 in complexes with either cognate site was revealed in supershift experiments. The C-terminus of Sp1 interacts with nuclear receptors. Both the ligand- and DNA-binding domains of the receptor are important for complex formation with Sp1 and GC-rich DNA. In spite of similar capacity to form ternary complexes, RAR but not TR up-regulated an Sp1-driven reporter in a ligand-dependent way. Thus additional factors limit the transcriptional response mediated by nuclear receptors and Sp1. PMID:11104684

  13. 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.

  14. Synthesis and structural characterization of ternary Cu (II) complexes of glycine with 2,2'-bipyridine and 2,2'-dipyridylamine. The DNA-binding studies and biological activity

    NASA Astrophysics Data System (ADS)

    Mohamed, Mervat S.; Shoukry, Azza A.; Ali, Ayat G.

    2012-02-01

    In this study two new complexes [Cu(bpy)(Gly)Cl]·2H 2O ( 1) and [Cu(dpa)(Gly)Cl]·2H 2O ( 2) (bpy = 2,2'-bipyridine; dpa = 2,2'-dipyridylamine, Gly = glycine) have been synthesized and characterized by elemental analysis, IR, TGA, UV-vis and magnetic susceptibility measurements. The binding properties of the complexes with CT-DNA were investigated by electronic absorption spectra. The intrinsic binding constants ( Kb) calculated from UV-vis absorption studies were 1.84 × 10 3 M -1 and 3.1 × 10 3 M -1 for complexes 1 and 2 respectively. Thermal denaturation has been systematically studied by spectrophotometric method and the calculated Δ Tm was nearly 5 °C for each complex. All the results suggest that the interaction modes between the complexes and CT-DNA were electrostatic and/or groove binding. The redox behavior of the two complexes was investigated by cyclic voltammetry. Both complexes, in presence and absence of CT-DNA show a quasi-reversible wave corresponding to Cu II/Cu I redox couple. The change in E1/2, Δ E and Ipc/ Ipa ascertain the interaction of complexes 1 and 2 with CT-DNA. Further insight into the binding of complexes with CT-DNA has been made by gel electrophoresis, where the binding of complexes is confirmed through decreasing the mobility and intensity of DNA bands. In addition, the antitumor activity of the complexes was tested on two cancer cell lines; the breast cancer (MCF7) and the human hepatocellular carcinoma (HEPG2), as well as one normal cell line; the human normal melanocytes (HFB4). The results showed that complex 1 was more potent antitumor agent than complex 2. The in-vitro antimicrobial activity of the two complexes was carried out using the disc diffusion method against different species of pathogenic bacteria and fungi. The activity data showed that complex 2 was more active in inhibiting the growth of the tested organisms.

  15. Ternary WD40 Repeat-Containing Protein Complexes: Evolution, Composition and Roles in Plant Immunity

    PubMed Central

    Miller, Jimi C.; Chezem, William R.; Clay, Nicole K.

    2016-01-01

    Plants, like mammals, rely on their innate immune system to perceive and discriminate among the majority of their microbial pathogens. Unlike mammals, plants respond to this molecular dialog by unleashing a complex chemical arsenal of defense metabolites to resist or evade pathogen infection. In basal or non-host resistance, plants utilize signal transduction pathways to detect “non-self,” “damaged-self,” and “altered-self”- associated molecular patterns and translate these “danger” signals into largely inducible chemical defenses. The WD40 repeat (WDR)-containing proteins Gβ and TTG1 are constituents of two independent ternary protein complexes functioning at opposite ends of a plant immune signaling pathway. They are also encoded by single-copy genes that are ubiquitous in higher plants, implying the limited diversity and functional conservation of their respective complexes. In this review, we summarize what is currently known about the evolutionary history of these WDR-containing ternary complexes, their repertoire and combinatorial interactions, and their downstream effectors and pathways in plant defense. PMID:26779203

  16. Supramolecular alignment of gold nanorods via cucurbit[8]uril ternary complex formation

    NASA Astrophysics Data System (ADS)

    Jones, Samuel T.; Zayed, Jameel M.; Scherman, Oren A.

    2013-05-01

    We have shown, for the first time, that a three component system is capable of aligning gold nanorods (AuNRs) through supramolecular host-guest interactions leading to control over AuNR end-to-end assembly. Viologen end-functionalised AuNRs were prepared that were capable of selectively binding to a cucurbit[8]uril (CB[8]) macrocyclic host molecule. These end-functionalised AuNRs could participate in 1 : 1 : 1 ternary complexation with synthesised telechelic linker molecules bearing second guest moieties, in the presence of CB[8]. When the linker length was long and flexible aggregation and precipitation of AuNRs were readily observed, but with no control over the AuNR conformation. On the other hand, when the linker length was shortened thereby imparting a more rigid connection between neighboring gold nanorods, the end-to-end assembly of AuNRs was achieved. We also note that in the presence of a molecule capable of occupying the entirety of the CB[8] cavity, end-to-end assembly is not observed as the system's ability to form a 1 : 1 : 1 ternary complex is halted. Thus, the end-to-end assembly relies upon both having a relatively short and rigid linker as well as the specific, yet tuneable supramolecular 1 : 1 : 1 ternary complexation between the three components.We have shown, for the first time, that a three component system is capable of aligning gold nanorods (AuNRs) through supramolecular host-guest interactions leading to control over AuNR end-to-end assembly. Viologen end-functionalised AuNRs were prepared that were capable of selectively binding to a cucurbit[8]uril (CB[8]) macrocyclic host molecule. These end-functionalised AuNRs could participate in 1 : 1 : 1 ternary complexation with synthesised telechelic linker molecules bearing second guest moieties, in the presence of CB[8]. When the linker length was long and flexible aggregation and precipitation of AuNRs were readily observed, but with no control over the AuNR conformation. On the other hand

  17. Pax-5 (BSAP) recruits Ets proto-oncogene family proteins to form functional ternary complexes on a B-cell-specific promoter.

    PubMed

    Fitzsimmons, D; Hodsdon, W; Wheat, W; Maira, S M; Wasylyk, B; Hagman, J

    1996-09-01

    The paired box transcription factor Pax-5 (B-cell-specific activator protein) is a key regulator of lineage-specific gene expression and differentiation in B-lymphocytes. We show that Pax-5 functions as a cell type-specific docking protein that facilitates binding of the early B-cell-specific mb-1 promoter by proteins of the Ets proto-oncogene family. Transcriptional activity of the mb-1 promoter in pre-B-cells is critically dependent on binding sites for Pax-5:Ets complexes. Ternary complex assembly requires only the Pax-5 paired box and ETS DNA-binding domains. Mutation of a single base pair in the ternary complex binding site allows for independent binding by Ets proteins but, conversely, inhibits the binding of Pax-5 by itself. Strikingly, the mutation reverses the pattern of complex assembly: Ets proteins recruit Pax-5 to bind the mutated sequence. Recruitment of Net and Elk-1, but not SAP1a, by Pax-5 defines a functional difference between closely related Ets proteins. Replacement of a valine (V68) in the ETS domain of SAP1a by aspartic acid (as found in c-Ets-1, Elk-1, and Net) enhanced ternary complex formation by more than 60-fold. Together, these observations define novel transcription factor interactions that regulate gene expression in B cells. PMID:8804314

  18. Comparative spectroscopic and DFT calculations of binary and ternary complexes derived from 4-allyl-1-(2-hydroxybenzoyl) thiosemicarbazide (L¹) and 2,2'-dipyridyl.

    PubMed

    Mlahi, Mossad R; Azhari, Shaker J; El-Asmy, Ahmed A; Mostafa, Mohsen M

    2015-01-01

    Five metal complexes derived the reactions of 4-allyl-1-(2-hydroxybenzoyl) thiosemicarbazide (L(1)) with MX2 (M=Co(2+), Cu(2+) and Zn(2+) ions; X=Cl(-) in case of Co(2+) and Cu(2+) ions and Cl(-) and Ac(-) in case of Zn(2+) ion) in EtOH were synthesized and characterized. The results suggested that the binary and ternary complexes have the general formulae, [Cu(L(1)-2H)(EtOH)], [Co(L(1)-2H)(H₂O)₂]⋅H₂O and [Zn(L(1)-2H) (H₂O)1/2]⋅½EtOH, [Cu₂(dipy)(L(1)-2H)(OH)₂(H₂O)], [Co(dipy)(L(1)-2H)]⋅4H₂O and [Zn(dipy)(L(1)-2H)]. The binary and ternary complexes were characterized by elemental analyses, molar conductivities, spectral (IR, UV-vis; (1)H NMR, mass), thermal (TGA, DTG) and magnetic moments measurements. The mode of chelation is suggested using spectral data. The existence of OH group in the ternary complexes is confirmed from the results of IR, mass and (1)H NMR spectra. All the geometries of the ligands and the complexes are confirmed using DFT method from DMOL(3). The biological activity for the L(1) and two metal complexes were tested against DNA. PMID:25036455

  19. Comparative spectroscopic and DFT calculations of binary and ternary complexes derived from 4-allyl-1-(2-hydroxybenzoyl) thiosemicarbazide (L1) and 2,2‧-dipyridyl

    NASA Astrophysics Data System (ADS)

    Mlahi, Mossad R.; Azhari, Shaker J.; El-Asmy, Ahmed A.; Mostafa, Mohsen M.

    2015-01-01

    Five metal complexes derived the reactions of 4-allyl-1-(2-hydroxybenzoyl) thiosemicarbazide (L1) with MX2 (M = Co2+, Cu2+ and Zn2+ ions; X = Cl- in case of Co2+ and Cu2+ ions and Cl- and Ac- in case of Zn2+ ion) in EtOH were synthesized and characterized. The results suggested that the binary and ternary complexes have the general formulae, [Cu(L1-2H)(EtOH)], [Co(L1-2H)(H2O)2]ṡH2O and [Zn(L1-2H) (H2O)1/2]ṡ½EtOH, [Cu2(dipy)(L1-2H)(OH)2(H2O)], [Co(dipy)(L1-2H)]ṡ4H2O and [Zn(dipy)(L1-2H)]. The binary and ternary complexes were characterized by elemental analyses, molar conductivities, spectral (IR, UV-vis; 1H NMR, mass), thermal (TGA, DTG) and magnetic moments measurements. The mode of chelation is suggested using spectral data. The existence of OH group in the ternary complexes is confirmed from the results of IR, mass and 1H NMR spectra. All the geometries of the ligands and the complexes are confirmed using DFT method from DMOL3. The biological activity for the L1 and two metal complexes were tested against DNA.

  20. Copper(II) and cadmium(II) sorption onto ferrihydrite in the presence of phthalic acid: some properties of the ternary complex.

    PubMed

    Song, Yantao; Swedlund, Peter J; Singhal, Naresh

    2008-06-01

    Copper, cadmium, and phthalic acid (H2Lp) adsorption by ferrihydrite was examined for binary and ternary systems. In binary systems adsorption was well reproduced using the diffuse layer model (DLM), and H2Lp adsorption was analogous to that of inorganic diprotic acids in terms of the relationship between the adsorption constants and acidity constants. In ternary systems H2Lp caused both the enhancement (due to ternary complexformation) and inhibition (due to solution complex formation) of Cu2+ and Cd2+ sorption depending on the conditions. The DLM could only describe the effect of H2Lp on metal ion sorption by including ternary complexes of the form [triple bond]FeOHMLp (0), where [triple bond]FeOH is a surface site and M is Cu or Cd. The relationship between binary metal adsorption constants and the ternary complex adsorption constants from this and previous studies suggest several properties of ternary complexes. First, ternary complex structures on both ferrihydrite and goethite are either the same or similar. Second, those cations having large adsorption constants also have large equilibrium constants for ternary complex formation. Third, ligands forming stronger solution complexes with cations will also form stronger surface ternary complexes though, because of the strong solution complex, they will not necessarily enhance cation adsorption. PMID:18589959

  1. Probing Ternary Complex Equilibria of Crown Ether Ligands by Time-Resolved Fluorescence Spectroscopy

    PubMed Central

    2015-01-01

    Ternary complex formation with solvent molecules and other adventitious ligands may compromise the performance of metal-ion-selective fluorescent probes. As Ca(II) can accommodate more than 6 donors in the first coordination sphere, commonly used crown ether ligands are prone to ternary complex formation with this cation. The steric strain imposed by auxiliary ligands, however, may result in an ensemble of rapidly equilibrating coordination species with varying degrees of interaction between the cation and the specific donor atoms mediating the fluorescence response, thus diminishing the change in fluorescence properties upon Ca(II) binding. To explore the influence of ligand architecture on these equilibria, we tethered two structurally distinct aza-15-crown-5 ligands to pyrazoline fluorophores as reporters. Due to ultrafast photoinduced electron-transfer (PET) quenching of the fluorophore by the ligand moiety, the fluorescence decay profile directly reflects the species composition in the ground state. By adjusting the PET driving force through electronic tuning of the pyrazoline fluorophores, we were able to differentiate between species with only subtle variations in PET donor abilities. Concluding from a global analysis of the corresponding fluorescence decay profiles, the coordination species composition was indeed strongly dependent on the ligand architecture. Altogether, the combination of time-resolved fluorescence spectroscopy with selective tuning of the PET driving force represents an effective analytical tool to study dynamic coordination equilibria and thus to optimize ligand architectures for the design of high-contrast cation-responsive fluorescence switches. PMID:25313708

  2. Synthesis and spectral characterization of ternary mixed-vanadyl β-diketonate complexes with Schiff bases

    NASA Astrophysics Data System (ADS)

    Baranwal, Balram Prasad; Tripathi, Kiran; Singh, Alok Kumar; Tripathi, Saurabh

    2012-06-01

    A new method to synthesize some mononuclear ternary oxovanadium(IV) complexes of the general formula [VO(β-dike)(SB)] (where Hβ-dike = acetylacetone; benzoylacetone or dibenzoylmethane, HSB = Schiff bases) has been explored by stepwise substitutions of acetylacetonate ion of VO(acac)2 with Schiff bases. The substituted acetylacetone could be fractionated out with p-xylene as an azeotrope. The complexes were characterized by elemental analyses, molecular weight determinations, spectral (electronic, infrared, 1H NMR, EPR and powder XRD) studies, magnetic susceptibility measurements and cyclic voltammetry. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bidentate chelating nature of β-diketones and Schiff base anions in the complexes was established by infrared and NMR spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. The EPR spectra illustrated coupling of the unpaired electron with 51V nucleus (I = 7/2). Cyclic voltammograms of all the complexes displayed two-step oxidation processes. The oxidation peak potential corresponded to the quasireversible one-electron oxidation process of the metal center, yielding V(V) species. Transmission electron microscopy (TEM) indicated spherical particles of ˜200 nm diameter. The synthesized complexes are mixed-ligand complexes showing a considerable hydrolytic stability in which vanadium is having coordination number 5. A square pyramidal geometry around vanadium has been assigned in all the complexes.

  3. Synthesis and spectral characterization of ternary mixed-vanadyl β-diketonate complexes with Schiff bases.

    PubMed

    Baranwal, Balram Prasad; Tripathi, Kiran; Singh, Alok Kumar; Tripathi, Saurabh

    2012-06-01

    A new method to synthesize some mononuclear ternary oxovanadium(IV) complexes of the general formula [VO(β-dike)(SB)] (where Hβ-dike=acetylacetone; benzoylacetone or dibenzoylmethane, HSB=Schiff bases) has been explored by stepwise substitutions of acetylacetonate ion of VO(acac)(2) with Schiff bases. The substituted acetylacetone could be fractionated out with p-xylene as an azeotrope. The complexes were characterized by elemental analyses, molecular weight determinations, spectral (electronic, infrared, (1)H NMR, EPR and powder XRD) studies, magnetic susceptibility measurements and cyclic voltammetry. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bidentate chelating nature of β-diketones and Schiff base anions in the complexes was established by infrared and NMR spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. The EPR spectra illustrated coupling of the unpaired electron with (51)V nucleus (I=7/2). Cyclic voltammograms of all the complexes displayed two-step oxidation processes. The oxidation peak potential corresponded to the quasireversible one-electron oxidation process of the metal center, yielding V(V) species. Transmission electron microscopy (TEM) indicated spherical particles of ∼200 nm diameter. The synthesized complexes are mixed-ligand complexes showing a considerable hydrolytic stability in which vanadium is having coordination number 5. A square pyramidal geometry around vanadium has been assigned in all the complexes. PMID:22387685

  4. Electrokinetic probes for single-step screening of polyol stereoisomers: the virtues of ternary boronate ester complex formation.

    PubMed

    Kaiser, Claire; Segui-Lines, Giselle; D'Amaral, Jason C; Ptolemy, Adam S; Britz-McKibbin, Philip

    2008-01-21

    Electrokinetic probes based on the differential migration of ternary boronate ester complexes permit the selective analysis of micromolar levels of UV-transparent polyol stereoisomers in urine samples via dynamic complexation-capillary electrophoresis that is applicable to single-step screening of in-born errors of sugar metabolism, such as galactosemia. PMID:18399200

  5. Pip, a lymphoid-restricted IRF, contains a regulatory domain that is important for autoinhibition and ternary complex formation with the Ets factor PU.1.

    PubMed

    Brass, A L; Kehrli, E; Eisenbeis, C F; Storb, U; Singh, H

    1996-09-15

    Pip is a lymphoid-restricted IRF transcription factor that is recruited to composite elements within immunoglobulin light-chain gene enhancers through a specific interaction with the Ets factor PU.1. We have examined the transcriptional regulatory properties of Pip as well as the requirements for its interaction with PU.1 and DNA to form a ternary complex. We demonstrate that Pip is a dichotomous regulator; it specifically stimulates transcription in conjunction with PU.1, but represses alpha/beta-interferon-inducible transcription in the absence of PU.1. Thus, during B-cell activation and differentiation, Pip may function both as an activator to promote B cell-specific gene expression and as a repressor to inhibit the antiproliferative effects of alpha/beta-interferons. Mutational analysis of Pip reveals a carboxy-terminal segment that is important for autoinhibition of DNA binding and ternary complex formation. A domain of Pip containing this segment confers autoinhibition and PU.1-dependent binding activity to the DNA-binding domain of the related IRF family member, p48. On the basis of these and other data we propose a model for PU.1/Pip ternary complex formation. PMID:8824592

  6. Functional Insights into Human HMG-CoA Lyase from Structures of Acyl-CoA-containing Ternary Complexes

    SciTech Connect

    Fu, Zhuji; Runquist, Jennifer A.; Montgomery, Christa; Miziorko, Henry M.; Kim, Jung-Ja P.

    2010-08-16

    HMG-CoA lyase (HMGCL) is crucial to ketogenesis, and inherited human mutations are potentially lethal. Detailed understanding of the HMGCL reaction mechanism and the molecular basis for correlating human mutations with enzyme deficiency have been limited by the lack of structural information for enzyme liganded to an acyl-CoA substrate or inhibitor. Crystal structures of ternary complexes of WT HMGCL with the competitive inhibitor 3-hydroxyglutaryl-CoA and of the catalytically deficient HMGCL R41M mutant with substrate HMG-CoA have been determined to 2.4 and 2.2 {angstrom}, respectively. Comparison of these {beta}/{alpha}-barrel structures with those of unliganded HMGCL and R41M reveals substantial differences for Mg{sup 2+} coordination and positioning of the flexible loop containing the conserved HMGCL 'signature' sequence. In the R41M-Mg{sup 2+}-substrate ternary complex, loop residue Cys{sup 266} (implicated in active-site function by mechanistic and mutagenesis observations) is more closely juxtaposed to the catalytic site than in the case of unliganded enzyme or the WT enzyme-Mg{sup 2+}-3-hydroxyglutaryl-CoA inhibitor complex. In both ternary complexes, the S-stereoisomer of substrate or inhibitor is specifically bound, in accord with the observed Mg{sup 2+} liganding of both C3 hydroxyl and C5 carboxyl oxygens. In addition to His{sup 233} and His{sup 235} imidazoles, other Mg{sup 2+} ligands are the Asp{sup 42} carboxyl oxygen and an ordered water molecule. This water, positioned between Asp{sup 42} and the C3 hydroxyl of bound substrate/inhibitor, may function as a proton shuttle. The observed interaction of Arg{sup 41} with the acyl-CoA C1 carbonyl oxygen explains the effects of Arg{sup 41} mutation on reaction product enolization and explains why human Arg{sup 41} mutations cause drastic enzyme deficiency.

  7. Ternary complex consisting of DNA, polycation, and a natural polysaccharide of schizophyllan to induce cellular uptake by antigen presenting cells.

    PubMed

    Takeda, Yoichi; Shimada, Naohiko; Kaneko, Kenji; Shinkai, Seiji; Sakurai, Kazuo

    2007-04-01

    A natural polysaccharide called schizophyllan (SPG) can form a complex with polynucleotides, and the complex has been shown to deliver biofunctional short DNAs such as antisense DNAs and CpG-DNAs. Although it is a novel and efficient method, there is a drawback: attachment of homo-polynucleotide tails [for example, poly(dA) or poly(C)] to the end of DNA is necessary to stabilize the complex, because DNA heterosequences cannot bind to SPG. The aim of this paper is to present an alternative method in which SPG/DNA complexes can be made without using the tails. The basic strategy is as follows: since SPG can form hydrophobic domains in aqueous solutions, hydrophobic objects should be encapsulated by this domain. DNA alone is highly hydrophilic; however, once DNA/polycation complexes are made, they should be included by the SPG hydrophobic domain. The aim of this paper is to prove the formation of the polycation/DNA/SPG ternary complex. Gel electrophoresis showed that presence of SPG influenced the migration pattern of polycation+DNA mixtures. With increasing the SPG ratio, the zeta potential (zeta) of the polycation+DNA+SPG mixture decreased drastically to reach almost zeta = 0 and the particle size distributions were altered due to the ternary complex formation. Confocal laser scanning microscopy revealed that the polycation/DNA/SPG ternary complexes showed high uptake efficiency when the complexes were exposed to macrophage-like cells (J774.A1). IL-12 secretion was enhanced when CpG-DNA was added as the ternary complex. These features can be ascribed to the fact that J774.A1 has a SPG recognition site called Dectin-1 on the cellular surface and the ternary complex can be ingested by this pathway. PMID:17328571

  8. Recognition and sensing of low-epitope targets via ternary complexes with oligonucleotides and synthetic receptors

    NASA Astrophysics Data System (ADS)

    Yang, Kyung-Ae; Barbu, Mihaela; Halim, Marlin; Pallavi, Payal; Kim, Benjamin; Kolpashchikov, Dmitry M.; Pecic, Stevan; Taylor, Steven; Worgall, Tilla S.; Stojanovic, Milan N.

    2014-11-01

    Oligonucleotide-based receptors or aptamers can interact with small molecules, but the ability to achieve high-affinity and specificity of these interactions depends strongly on functional groups or epitopes displayed by the binding targets. Some classes of targets are particularly challenging: for example, monosaccharides have scarce functionalities and no aptamers have been reported to recognize, let alone distinguish from each other, glucose and other hexoses. Here we report aptamers that differentiate low-epitope targets such as glucose, fructose or galactose by forming ternary complexes with high-epitope organic receptors for monosaccharides. In a follow-up example, we expand this method to isolate high-affinity oligonucleotides against aromatic amino acids complexed in situ with a nonspecific organometallic receptor. The method is general and enables broad clinical use of aptamers for the detection of small molecules in mix-and-measure assays, as demonstrated by monitoring postprandial waves of phenylalanine in human subjects.

  9. Engineering the Morphology and Configuration of Ternary Heterostructures for Improving Their Photocatalytic Activity.

    PubMed

    Li, Kui; Chen, Rong; Li, Shun-Li; Xie, Shuai-Lei; Cao, Xue-Li; Dong, Long-Zhang; Bao, Jian-Chun; Lan, Ya-Qian

    2016-02-01

    Heteronanomaterials composed of suitable semiconductors enable the direct conversion from solar power into clean and renewable energy. Ternary heterostructures with appropriate configuration and morphology possess rich and varied properties, especially for improving the photocatalytic activity and stability synchronously. However, suitable ternary heterostructure prototypes and facile while effective strategy for modulating their morphology and configuration are still scarce. Herein, various ternary ZnS-CdS-Zn(1-x)Cd(x)S heterostructures with tunable morphology (0 to 2 D) and semiconductor configurations (randomly distributed, interface mediated, and quantum dots sensitized core@shell heterostructures) were facilely synthesized via one-pot hydrothermal method resulting from the different molecular structures of the amine solvents. Semiconductor morphology, especially configuration of the ternary heterostructure, shows dramatic effect on their photocatalytic activity. The CdS sensitized porous Zn(1-x)CdxS@ZnS core@shell takes full advantage of ZnS, Zn(1-x)Cd(x)S and CdS and shows the maximal photocatalytic H2-production rate of 100.2 mmol/h/g and excellent stability over 30 h. This study provides some guidelines for the design and synthesis of high-performance ternary heterostructure via modulation of semiconductor configuration and morphology using one-pot method. PMID:26835705

  10. A Phosphole Oxide-Containing Organogold(III) Complex for Solution-Processable Resistive Memory Devices with Ternary Memory Performances.

    PubMed

    Hong, Eugene Yau-Hin; Poon, Chun-Ting; Yam, Vivian Wing-Wah

    2016-05-25

    A novel class of luminescent phosphole oxide-containing alkynylgold(III) complex has been synthesized, characterized, and applied as active material in the fabrication of solution-processable resistive memory devices. Incorporation of the phosphole oxide moiety in gold(III) system has been demonstrated to provide an extra charge-trapping site, giving rise to intriguing ternary memory performances with distinct and low switching threshold voltages, high OFF/ON1/ON2 current ratio of 1/10(3)/10(7), and long retention time for the three states. The present study offers vital insights for the future development of multilevel memory devices using small-molecule organometallic compounds. PMID:27163338

  11. Ternary Porphyrinato Hf(IV) and Zr(IV) - Polyoxometalate Complexes

    PubMed Central

    Falber, Alexander; Burton-Pye, Benjamin P.; Radivojevic, Ivana; Todaro, Louis; Saleh, Raihan; Francesconi, Lynn; Drain, Charles Michael

    2010-01-01

    We report a facile, high yield synthesis and characterization of discrete, ternary porphyrin-metal-polyoxometalate (Por-M-POM) complexes where a group (IV) transition metal ion is bound both to the porphyrin core and to the lacunary site of a Keggin POM, PW11O39−7. The remarkably robust complexes exploit the fact that Hf(IV) and Zr(IV) are 7–8 coordinate and reside outside the plane of the porphyrin macrocycle, thus enabling the simultaneous coordination to meso-tetraphenylporphyrin (TPP) or meso-tetra(4-pyridyl)porphyrin (TPyP) and to the defect site in the Keggin framework. The physical properties of the (TPP)Hf(PW11O39)[TBA]5, (TPyP)Hf(PW11O39)[TBA]5, and (TPP)Zr(PW11O39)[TBA]5 complexes are similar because the metal ions have similar oxidation states, and coordination chemistry. This architecture couples the photonic properties of the porphyrin to the POM because the metal ion is incorporated into both frameworks. Thus the ternary complexes can serve as a basis for the characterization of Hf(IV) and Zr(IV) porphyrins bound to oxide surfaces via the group (IV) metal ions. The Hf(Por) and Zr(Por) bind strongly to TiO2 nanoparticles and indium tin oxide (ITO) surfaces, but significantly less binds to crystalline SiO2 or TiO2 surfaces. Together, the strong binding of the metalloporphyrins to the POM, nanoparticles, and the ITO surfaces, and paucity of binding to crystalline surfaces, suggests that the 3–4 open coordination sites on the Hf(Por) and Zr(Por) are predominantly bound at surface defect sites. PMID:20543903

  12. An ultrafast molecular rotor based ternary complex in a nanocavity: a potential "turn on" fluorescence sensor for the hydrocarbon chain.

    PubMed

    Murudkar, Sushant; Mora, Aruna K; Singh, Prabhat K; Bandyopadhyay, Tusar; Nath, Sukhendu

    2015-02-28

    Formation of a ternary complex by an ultrafast molecular rotor (UMR) with a macrocyclic cavitand has been investigated for the sensitive detection of the alkyl chain of a surfactant. A benzothiazole based UMR, Thioflavin-T (ThT), has been used as a fluorescent probe. It is shown that ThT forms a very weak inclusion complex with γ-cyclodextrin (γ-CD) with an association constant of 8.8 M(-1). However, the addition of a small amount of surfactant results in a significant increase in the emission intensity of ThT in γ-CD solution. From detailed steady-state and time-resolved fluorescence measurements and NMR studies, it has been inferred that the addition of the surfactant results in the formation of a ternary complex through the inclusion of its alkyl chain inside the γ-CD nanocavity. In such a ternary complex, the non-radiative torsional motion in ThT is largely prevented due to a large increase in the frictional force inside the nanocavity and results in a significant fluorescence enhancement. The formation of the binary and the ternary complexes in the present system has been further supported by the molecular docking and subsequent molecular dynamics simulation studies. The present result indicates that the inclusion complex with an UMR as a guest could be a potential candidate for the efficient detection of insoluble organic molecules, especially hydrocarbons. PMID:25623640

  13. Rapid-mix flow cytometry measurements of subsecond regulation of G protein-coupled receptor ternary complex dynamics by guanine nucleotides.

    PubMed

    Wu, Yang; Buranda, Tione; Simons, Peter C; Lopez, Gabriel P; McIntire, William E; Garrison, James C; Prossnitz, Eric R; Sklar, Larry A

    2007-12-01

    We have used rapid-mix flow cytometry to analyze the early subsecond dynamics of the disassembly of ternary complexes of G protein-coupled receptors (GPCRs) immobilized on beads to examine individual steps associated with guanine nucleotide activation. Our earlier studies suggested that the slow dissociation of Galpha and Gbetagamma subunits was unlikely to be an essential component of cell activation. However, these studies did not have adequate time resolution to define precisely the disassembly kinetics. Ternary complexes were assembled using three formyl peptide receptor constructs (wild type, formyl peptide receptor-Galpha(i2) fusion, and formyl peptide receptor-green fluorescent protein fusion) and two isotypes of the alpha subunit (alpha(i2) and alpha(i3)) and betagamma dimer (beta(1)gamma(2) and beta(4)gamma(2)). At saturating nucleotide levels, the disassembly of a significant fraction of ternary complexes occurred on a subsecond time frame for alpha(i2) complexes and tau(1/2)< or =4s for alpha(i3) complexes, time scales that are compatible with cell activation. beta(1)gamma(2) isotype complexes were generally more stable than beta(4)gamma(2)-associated complexes. The comparison of the three constructs, however, proved that the fast step was associated with the separation of receptor and G protein and that the dissociation of the ligand or of the alpha and betagamma subunits was slower. These results are compatible with a cell activation model involving G protein conformational changes rather than disassembly of Galphabetagamma heterotrimer. PMID:17904091

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

    SciTech Connect

    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 explains 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.

  15. Gelatin/chitosan/hyaluronan ternary complex scaffold containing basic fibroblast growth factor for cartilage tissue engineering.

    PubMed

    Tan, Huaping; Gong, Yihong; Lao, Lihong; Mao, Zhengwei; Gao, Changyou

    2007-10-01

    Gelatin, chitosan and hyaluronan with a weight ratio of 82.6%, 16.5% and 0.1% were chosen as a scaffold material to mimic the composition of natural cartilage matrix for cartilage tissue engineering. Water soluble carbodiimide was added into the biomacromolecule solution with a concentration of 5% to crosslink the complex. Following a freeze-drying procedure, a porous scaffold (control) was then prepared. To enhance chondrogenesis, heparin was covalently immobilized onto the scaffold by carbodiimide chemistry, through which basic fibroblast growth factor (bFGF) was further incorporated by a bioaffinity force. Incubation in phosphate buffered saline (PBS, pH 7.4) at 37 degrees C caused the weight loss of all kinds of the scaffolds, which could be brought by both the degradation and dissolution of the biomacromolecules. Compared with the control, however, the heparinized scaffold showed stronger ability to resist the weight loss, implying that a higher crosslinking degree was achieved by incorporation of the heparin. Rabbit auricular chondrocytes were seeded onto the ternary complex scaffold containing bFGF to assess cell response. Chondrocytes could adhere and proliferate in all kinds of the scaffold, regardless of the existence of bFGF. No significant difference on glycosaminoglycan (GAG) secretion was recorded between these scaffolds after cultured for 7 and 21 days too, although the absolute value from the Scaffold-heparin-bFGF was somewhat higher. However, chondrocytes seeded in the Scaffold-heparin-bFGF indeed showed significant higher viability than that on the control scaffold. These results reveal that the ternary complex scaffolds, in particular the one containing bFGF, are a potential candidate for cartilage tissue engineering. PMID:17554603

  16. Modification of amino groups in EF-Tu.GTP and the ternary complex EF-Tu.GTP.valyl-tRNAVal.

    PubMed

    Antonsson, B; Leberman, R

    1984-06-15

    In an attempt to describe the binding region of EF-Tu . GTP for aminoacyl-tRNA, the epsilon-amino groups of the lysine residues of the protein molecule in the GTP and ternary complexes were modified with ethyl acetimidate. Using [14C]ethyl acetimidate, tryptic digestion, fractionation of peptides by high-performance liquid chromatography, and amino acid analysis, all reactive lysine residues could be unambiguously identified. 19 of the 23 lysine residues of EF-Tu were labelled under conditions for ternary complex stability. Of these only 8 showed differences in reactivity between free and complexed EF-Tu . GTP. In the ternary complex lysine residues 208 and 390 [Jones, M. D., Petersen, T. E., Nielsen, K. M., Magnusson, S., Sotterup-Jensen, L., Gausing, K. and Clark, B. F. C. (1980) Eur. J. Biochem. 108, 507-526] showed an increase in reactivity (60% and 30% respectively) and residues 2, 4, 237, 248, 263, and 282 showed a decrease in reactivity (between 85% and 37%) compared to the values observed with EF-Tu . GTP. The greatest changes in reactivity were observed for lysine residues 2, 4 and 263. These data can be combined with the available structural information to identify possible areas of contact between the protein and nucleic acid moieties in the ternary complex. PMID:6430701

  17. Preparation of Pt-Ru-Ni ternary nanoparticles by microemulsion and electrocatalytic activity for methanol oxidation

    SciTech Connect

    Zhang Xin . E-mail: xzhang@stu.edu.cn; Zhang Feng; Guan Renfeng; Chan, K.-Y.

    2007-02-15

    Ternary platinum-ruthenium-nickel nanoparticles are prepared by water-in-oil reverse microemulsions of water/Triton X-100/propanol-2/cyclohexane. Nanoparticles formed in the microemulsions are characterized by transmission electron microscopy (TEM), electron diffraction (ED), X-ray diffractometry (XRD), energy dispersive X-ray analysis (EDX). These resulting materials showed a homogenous alloy structure, the mono-dispersion and an average diameter of 2.6 {+-} 0.3 nm with a narrow particle size distribution. The composition and particle size of ternary Pt-Ru-Ni nanoparticles can be controlled by adjusting the initial metal salt solution and preparation conditions. Pt-Ru-Ni ternary metallic nanoparticles showed an enhanced catalytic activity towards methanol oxidation compared to Pt-Ru bimetallic nanoparticles.

  18. Identification of a non-covalent ternary complex formed by PIAS1, SUMO1, and UBC9 proteins involved in transcriptional regulation.

    PubMed

    Mascle, Xavier H; Lussier-Price, Mathieu; Cappadocia, Laurent; Estephan, Patricia; Raiola, Luca; Omichinski, James G; Aubry, Muriel

    2013-12-20

    Post-translational modifications with ubiquitin-like proteins require three sequentially acting enzymes (E1, E2, and E3) that must unambiguously recognize each other in a coordinated fashion to achieve their functions. Although a single E2 (UBC9) and few RING-type E3s (PIAS) operate in the SUMOylation system, the molecular determinants regulating the interactions between UBC9 and the RING-type E3 enzymes are still not well defined. In this study we use biochemical and functional experiments to characterize the interactions between PIAS1 and UBC9. Our results reveal that UBC9 and PIAS1 are engaged both in a canonical E2·E3 interaction as well as assembled into a previously unidentified non-covalent ternary complex with SUMO as evidenced by bioluminescence resonance energy transfer, nuclear magnetic resonance spectroscopy, and isothermal titration calorimetry studies. In this ternary complex, SUMO functions as a bridge by forming non-overlapping interfaces with UBC9 and PIAS1. Moreover, our data suggest that phosphorylation of serine residues adjacent to the PIAS1 SUMO-interacting motif favors formation of the non covalent PIAS1·SUMO·UBC9 ternary complex. Finally, our results also indicate that the non-covalent ternary complex is required for the known transcriptional repression activities mediated by UBC9 and SUMO1. Taken together, the data enhance our knowledge concerning the mode of interaction of enzymes of the SUMOylation machinery as well as their role in transcriptional regulation and establishes a framework for investigations of other ubiquitin-like protein systems. PMID:24174529

  19. Identification of a Non-covalent Ternary Complex Formed by PIAS1, SUMO1, and UBC9 Proteins Involved in Transcriptional Regulation*

    PubMed Central

    Mascle, Xavier H.; Lussier-Price, Mathieu; Cappadocia, Laurent; Estephan, Patricia; Raiola, Luca; Omichinski, James G.; Aubry, Muriel

    2013-01-01

    Post-translational modifications with ubiquitin-like proteins require three sequentially acting enzymes (E1, E2, and E3) that must unambiguously recognize each other in a coordinated fashion to achieve their functions. Although a single E2 (UBC9) and few RING-type E3s (PIAS) operate in the SUMOylation system, the molecular determinants regulating the interactions between UBC9 and the RING-type E3 enzymes are still not well defined. In this study we use biochemical and functional experiments to characterize the interactions between PIAS1 and UBC9. Our results reveal that UBC9 and PIAS1 are engaged both in a canonical E2·E3 interaction as well as assembled into a previously unidentified non-covalent ternary complex with SUMO as evidenced by bioluminescence resonance energy transfer, nuclear magnetic resonance spectroscopy, and isothermal titration calorimetry studies. In this ternary complex, SUMO functions as a bridge by forming non-overlapping interfaces with UBC9 and PIAS1. Moreover, our data suggest that phosphorylation of serine residues adjacent to the PIAS1 SUMO-interacting motif favors formation of the non covalent PIAS1·SUMO·UBC9 ternary complex. Finally, our results also indicate that the non-covalent ternary complex is required for the known transcriptional repression activities mediated by UBC9 and SUMO1. Taken together, the data enhance our knowledge concerning the mode of interaction of enzymes of the SUMOylation machinery as well as their role in transcriptional regulation and establishes a framework for investigations of other ubiquitin-like protein systems. PMID:24174529

  20. Regulation of protein 4.1R, p55, and glycophorin C ternary complex in human erythrocyte membrane.

    PubMed

    Nunomura, W; Takakuwa, Y; Parra, M; Conboy, J; Mohandas, N

    2000-08-11

    Three binary protein-protein interactions, glycophorin C (GPC)-4.1R, GPC-p55, and p55-4.1R, constitute the GPC-4.1R-p55 ternary complex in the erythrocyte membrane. Little is known regarding the molecular basis for the interaction of 4.1R with either GPC or p55 and regarding the role of 4.1R in regulating the various protein-protein interactions that constitute the GPC-4.1R-p55 ternary complex. In the present study, we present evidence that sequences in the 30-kDa domain encoded by exon 8 and exon 10 of 4.1R constitute the binding interfaces for GPC and p55, respectively. We further show that 4.1R increases the affinity of p55 binding to GPC by an order of magnitude, implying that 4.1R modulates the interaction between p55 and GPC. Finally, we document that binding of calmodulin to 4.1R decreases the affinity of 4.1R interactions with both p55 and GPC in a Ca(2+)-dependent manner, implying that the GPC-4.1R-p55 ternary protein complex can undergo dynamic regulation in the erythrocyte membrane. Taken together, these findings have enabled us to identify an important role for 4.1R in regulating the GPC-4.1R-p55 ternary complex in the erythrocyte membrane. PMID:10831591

  1. Crystallization and preliminary X-ray diffraction analysis of the ternary human GM-CSF receptor complex

    SciTech Connect

    Hansen, Guido; Hercus, Timothy R.; Xu, Yibin; Lopez, Angel F.; Parker, Michael W.; McKinstry, William J.

    2008-08-01

    Crystals of the soluble ternary GM-CSF receptor complex were obtained which diffracted to a resolution of 3.3 Å. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a haemopoietic growth factor that acts though a ternary receptor signalling complex containing specific α (GMRα) and common β (βc) receptor subunits. Human GM-CSF is encoded by the gene csf2, while the genes for GMRα and βc are csf2ra and csf2rb, respectively. Crystals of the ternary ectodomain complex comprising GM-CSF and the soluble extracellular regions of both the GMRα subunit and either βc or its glutamine-substitution mutant N346Q were obtained using the hanging-drop vapour-diffusion method. The best diffracting crystals of the ternary complex were obtained using the N346Q mutation of the βc subunit. These crystals grew using polyethylene glycol 3350 with a high concentration of proline, belonged to space group P6{sub 3}22 and diffracted to 3.3 Å resolution.

  2. 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

  3. Net-b, a Ras-insensitive factor that forms ternary complexes with serum response factor on the serum response element of the fos promoter.

    PubMed

    Giovane, A; Sobieszczuk, P; Ayadi, A; Maira, S M; Wasylyk, B

    1997-10-01

    The Ras signalling pathway targets transcription factors such as the ternary complex factors that are recruited by the serum response factor to form complexes on the serum response element (SRE) of the fos promoter. We have identified a new ternary complex factor, Net-b. We report the features of the net gene and show that it produces several splice variants, net-b and net-c. net-b RNA and protein are expressed in a variety of tissues and cell lines. net-c RNA is expressed at low levels, and the protein was not detected, raising the possibility that it is a cryptic splice variant. We have studied the composition of ternary complexes that form on the SRE of the fos promoter with extracts from fibroblasts (NIH 3T3) cultured under various conditions and pre-B cells (70Z/3) before and after differentiation with lipopolysaccharide (LPS). The fibroblast complexes contain mainly Net-b followed by Sap1 and Elk1. Net-b complexes, as well as Sap1 and Elk1, are induced by epidermal growth factor (EGF) stimulation of cells cultured in low serum. Pre-B-cell complexes contain mainly Sap1, with less of Net-b and little of Elk1. There is little change upon LPS-induced differentiation compared to the increase with EGF in fibroblasts. We have also found that Net-b is a nuclear protein that constitutively represses transcription. Net-b is not activated by Ras signalling, in contrast to Net, Sap1a, and Elk1. We have previously reported that down-regulation of Net proteins with antisense RNA increases SRE activity. The increase in SRE activity is observed at low serum levels and is even greater after serum stimulation, showing that the SRE is under negative regulation by Net proteins and the level of repression increases during induction. Net-b, the predominant factor in ternary complexes in fibroblasts, may both keep the activity of the SRE low in the absence of strong inducing conditions and rapidly shut the activity off after stimulation. PMID:9315625

  4. Net-b, a Ras-insensitive factor that forms ternary complexes with serum response factor on the serum response element of the fos promoter.

    PubMed Central

    Giovane, A; Sobieszczuk, P; Ayadi, A; Maira, S M; Wasylyk, B

    1997-01-01

    The Ras signalling pathway targets transcription factors such as the ternary complex factors that are recruited by the serum response factor to form complexes on the serum response element (SRE) of the fos promoter. We have identified a new ternary complex factor, Net-b. We report the features of the net gene and show that it produces several splice variants, net-b and net-c. net-b RNA and protein are expressed in a variety of tissues and cell lines. net-c RNA is expressed at low levels, and the protein was not detected, raising the possibility that it is a cryptic splice variant. We have studied the composition of ternary complexes that form on the SRE of the fos promoter with extracts from fibroblasts (NIH 3T3) cultured under various conditions and pre-B cells (70Z/3) before and after differentiation with lipopolysaccharide (LPS). The fibroblast complexes contain mainly Net-b followed by Sap1 and Elk1. Net-b complexes, as well as Sap1 and Elk1, are induced by epidermal growth factor (EGF) stimulation of cells cultured in low serum. Pre-B-cell complexes contain mainly Sap1, with less of Net-b and little of Elk1. There is little change upon LPS-induced differentiation compared to the increase with EGF in fibroblasts. We have also found that Net-b is a nuclear protein that constitutively represses transcription. Net-b is not activated by Ras signalling, in contrast to Net, Sap1a, and Elk1. We have previously reported that down-regulation of Net proteins with antisense RNA increases SRE activity. The increase in SRE activity is observed at low serum levels and is even greater after serum stimulation, showing that the SRE is under negative regulation by Net proteins and the level of repression increases during induction. Net-b, the predominant factor in ternary complexes in fibroblasts, may both keep the activity of the SRE low in the absence of strong inducing conditions and rapidly shut the activity off after stimulation. PMID:9315625

  5. NMR studies on binary and ternary Pd(II) complexes formed by the growth-modulating tripeptide glycylhistidyllysine and nucleotides.

    PubMed

    Laussac, J P; Pasdeloup, M; Hadjiliadis, N

    1987-07-01

    The mechanism of transport of Pt(II) and Pd(II) into tissues through blood and that of their elimination in kidney is incompletely known so far. In this respect, the binding of palladium by the tripeptide glycyl-L-histidyl-L-lysine (GHL), a constituent of the human plasma, as a binary complex, and by the nucleotides 5'-IMP and 5'-GMP, as ternary complexes, has been studied by 1H and 13C NMR spectroscopy. These studies have been conducted in aqueous media and at different ligand/metal ratios. At acidic pH, resonances were observed for binary and ternary kinetically stable complexes, and binding sites in these complexes were identified by the effect of binding on chemical shifts of protons and carbon resonances. From these data, stoichiometries and structures of these complexes were proposed. PMID:2821192

  6. 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

  7. Crystal structure of a transcription factor IIIB core interface ternary complex.

    PubMed

    Juo, Z Sean; Kassavetis, George A; Wang, Jimin; Geiduschek, E Peter; Sigler, Paul B

    2003-04-01

    Transcription factor IIIB (TFIIIB), consisting of the TATA-binding protein (TBP), TFIIB-related factor (Brf1) and Bdp1, is a central component in basal and regulated transcription by RNA polymerase III. TFIIIB recruits its polymerase to the promoter and subsequently has an essential role in the formation of the open initiation complex. The amino-terminal half of Brf1 shares a high degree of sequence similarity with the polymerase II general transcription factor TFIIB, but it is the carboxy-terminal half of Brf1 that contributes most of its binding affinity with TBP. The principal anchoring region is located between residues 435 and 545 of yeast Brf1, comprising its homology domain II. The same region also provides the primary interface for assembling Bdp1 into the TFIIIB complex. We report here a 2.95 A resolution crystal structure of the ternary complex containing Brf1 homology domain II, the conserved region of TBP and 19 base pairs of U6 promoter DNA. The structure reveals the core interface for assembly of TFIIIB and demonstrates how the loosely packed Brf1 domain achieves remarkable binding specificity with the convex and lateral surfaces of TBP. PMID:12660736

  8. Lipophilic ternary complexes in liquid-liquid extraction of trivalent lanthanides

    SciTech Connect

    Lumetta, Gregg J.; Levitskaia, Tatiana G.; Latesky, Stanley; Henderson, Renesha V.; Edwards, Emilio A.; Braley, Jenifer C.; Sinkov, Sergey I.

    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 is 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).

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

    SciTech Connect

    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 to 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

  10. 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

  11. 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. PMID:24219402

  12. Synthesis, Characterization, and Thermochemical Study on a Ternary Complex [Sm( m-MOBA)3phen]2

    NASA Astrophysics Data System (ADS)

    Xiao, S. X.; Gu, H. W.; Zhang, J. J.; Xiao, H.; Ding, J.; Lu, X.

    2012-02-01

    A new ternary solid complex of samarium chloride hexahydrate with m-methoxybenzoic acid and 1,10-phenanthroline, [Sm( m-MOBA)3phen]2 ( m-MOBA: m-methoxybenzoic; phen: 1,10-phenanthroline), was synthesized and characterized by elemental analysis, IR spectra, UV spectra, molar conductance, and thermogravimetric analysis. The dissolution enthalpies of SmCl3·6H2O (s), m-HMOBA(s), phen·H2O (s), and [Sm( m-MOBA)3phen]2(s) in the calorimetric solvent (VDMF:VCYC:VHCl = 2:1:2) were determined by an advanced solution-reaction isoperibol calorimeter at 298.15 K, respectively. The standard molar enthalpy of reaction was determined to be {Δ_r H_m^θ =(233.97 ± 1.15) kJ {\\cdot} mol^{-1}}. In accordance with Hess' law, the standard molar enthalpy of formation of the title complex [Sm( m-MOBA)3phen]2(s) was estimated to be -(5054.6 ± 9.5) kJ · mol-1.

  13. Structural analysis of a holoenzyme complex of mouse dihydrofolate reductase with NADPH and a ternary complex with the potent and selective inhibitor 2, 4-diamino-6-(2′-hydroxydibenz[b, f]azepin-5-yl)methylpteridine

    SciTech Connect

    Cody, Vivian; Pace, Jim; Rosowsky, Andre

    2008-09-01

    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, 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

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

    SciTech Connect

    Esclapez, Julia; Britton, K. Linda; Baker, Patrick J.; Fisher, Martin; Pire, Carmen; Ferrer, Juan; Bonete, María José; Rice, David W.

    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 the 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.

  15. Crystal structure of Pseudomonas fluorescens mannitol 2-dehydrogenase binary and ternary complexes. Specificity and catalytic mechanism.

    PubMed

    Kavanagh, Kathryn L; Klimacek, Mario; Nidetzky, Bernd; Wilson, David K

    2002-11-01

    Long-chain mannitol dehydrogenases are secondary alcohol dehydrogenases that are of wide interest because of their involvement in metabolism and potential applications in agriculture, medicine, and industry. They differ from other alcohol and polyol dehydrogenases because they do not contain a conserved tyrosine and are not dependent on Zn(2+) or other metal cofactors. The structures of the long-chain mannitol 2-dehydrogenase (54 kDa) from Pseudomonas fluorescens in a binary complex with NAD(+) and ternary complex with NAD(+) and d-mannitol have been determined to resolutions of 1.7 and 1.8 A and R-factors of 0.171 and 0.176, respectively. These results show an N-terminal domain that includes a typical Rossmann fold. The C-terminal domain is primarily alpha-helical and mediates mannitol binding. The electron lone pair of Lys-295 is steered by hydrogen-bonding interactions with the amide oxygen of Asn-300 and the main-chain carbonyl oxygen of Val-229 to act as the general base. Asn-191 and Asn-300 are involved in a web of hydrogen bonding, which precisely orients the mannitol O2 proton for abstraction. These residues also aid in stabilizing a negative charge in the intermediate state and in preventing the formation of nonproductive complexes with the substrate. The catalytic lysine may be returned to its unprotonated state using a rectifying proton tunnel driven by Glu-292 oscillating among different environments. Despite low sequence homology, the closest structural neighbors are glycerol-3-phosphate dehydrogenase, N-(1-d-carboxylethyl)-l-norvaline dehydrogenase, UDP-glucose dehydrogenase, and 6-phosphogluconate dehydrogenase, indicating a possible evolutionary relationship among these enzymes. PMID:12196534

  16. The ternary complex factor Net contains two distinct elements that mediate different responses to MAP kinase signalling cascades.

    PubMed

    Ducret, C; Maira, S M; Lutz, Y; Wasylyk, B

    2000-10-19

    The ternary complex factors (TCFs), Elk-1, Sap-1a and Net, are key integrators of the transcriptional response to different signalling pathways. Classically, three MAP kinase pathways, involving ERK, JNK, and p38, transduce various extracellular stimuli to the nucleus. Net is a repressor that is converted into an activator by Ras/ERK signalling. Net is also exported from the nucleus in response to stress stimuli transduced through the JNK pathway, leading to relief from repression. Here we show that ERK and p38 bind to the D box and that binding is required for phosphorylation of the adjacent C-terminally located C-domain. The D box as well as the phosphorylation sites in the C-domain (the DC element) are required for transcription activation by Ras. On the other hand, JNK binds to the J box in the middle of the protein, and binding is required for phosphorylation of the adjacent EXport motif. Both the binding and phosphorylation sites (the JEX element) are important for Net export. In conclusion, specific targeting of Net by MAP kinase pathways involves two different docking sites and phosphorylation of two different domains. These two elements, DC and JEX, mediate two distinct functional responses. PMID:11042694

  17. The ternary complex factor net is downregulated by hypoxia and regulates hypoxia-responsive genes.

    PubMed

    Gross, Christian; Buchwalter, Gilles; Dubois-Pot, Hélène; Cler, Emilie; Zheng, Hong; Wasylyk, Bohdan

    2007-06-01

    Hypoxia and the Net ternary complex factor (TCF) regulate similar processes (angiogenesis, wound healing, and cellular migration) and genes (PAI-1, c-fos, erg-1, NOS-2, HO-1, and vascular endothelial growth factor genes), suggesting that they are involved in related pathways. We show here that hypoxia regulates Net differently from the other TCFs and that Net plays a role in the hypoxic response in vivo in mice and in cells. Hypoxia induces Net depletion from target promoters, nuclear export, ubiquitylation, and proteasomal degradation. Key mediators of the hypoxic response, the prolyl-4-hydroxylases containing domain proteins (PHDs), regulate Net. PHD downregulation in normoxia leads to Net degradation, and PHD overexpression delays Net downregulation by hypoxia. Net inhibition by RNA interference or mutation leads to altered regulation by hypoxia of the Net targets PAI-1, c-fos, and egr-1. We propose that hypoxia stimulates transcription of target promoters through removal of the repressor function of Net. Interestingly, the hematocrit response to a chemical inducer of hypoxia-like responses (cobalt chloride) is strongly altered in Net mutant mice. Our results show that the Net TCF is part of the biological response to hypoxia, adding a new component to an important pathological and physiological process. PMID:17403894

  18. Insights into the Sirtuin Mechanism from Ternary Complexes Containing NAD[superscript +] and Acetylated Peptide

    SciTech Connect

    Hoff, Kevin G.; Avalos, Jose L.; Sens, Kristin; Wolberger, Cynthia

    2010-07-22

    Sirtuin proteins comprise a unique class of NAD{sup +}-dependent protein deacetylases. Although several structures of sirtuins have been determined, the mechanism by which NAD{sup +} cleavage occurs has remained unclear. We report the structures of ternary complexes containing NAD{sup +} and acetylated peptide bound to the bacterial sirtuin Sir2Tm and to a catalytic mutant (Sir2Tm{sup H116Y}). NAD{sup +} in these structures binds in a conformation different from that seen in previous structures, exposing the {alpha} face of the nicotinamide ribose to the carbonyl oxygen of the acetyl lysine substrate. The NAD{sup +} conformation is identical in both structures, suggesting that proper coenzyme orientation is not dependent on contacts with the catalytic histidine. We also present the structure of Sir2Tm{sup H116A} bound to deacteylated peptide and 3{prime}-O-acetyl ADP ribose. Taken together, these structures suggest a mechanism for nicotinamide cleavage in which an invariant phenylalanine plays a central role in promoting formation of the O-alkylamidate reaction intermediate and preventing nicotinamide exchange.

  19. Ternary Complex of Transforming Growth Factor-[beta]1 Reveals Isoform-specific Ligand Recognition and Receptor Recruitment in the Superfamily

    SciTech Connect

    Radaev, Sergei; Zou, Zhongcheng; Huang, Tao; Lafer, Eileen M.; Hinck, Andrew P.; Sun, Peter D.

    2010-11-03

    Transforming growth factor (TGF)-{beta}1, -{beta}2, and -{beta}3 are 25-kDa homodimeric polypeptides that play crucial nonoverlapping roles in embryogenesis, tissue development, carcinogenesis, and immune regulation. Here we report the 3.0-{angstrom} resolution crystal structure of the ternary complex between human TGF-{beta}1 and the extracellular domains of its type I and type II receptors, T{beta}RI and T{beta}RII. The TGF-{beta}1 ternary complex structure is similar to previously reported TGF-{beta}3 complex except with a 10{sup o} rotation in T{beta}RI docking orientation. Quantitative binding studies showed distinct kinetics between the receptors and the isoforms of TGF-{beta}. T{beta}RI showed significant binding to TGF-{beta}2 and TGF-{beta}3 but not TGF-{beta}1, and the binding to all three isoforms of TGF-{beta} was enhanced considerably in the presence of T{beta}RII. The preference of TGF-{beta}2 to T{beta}RI suggests a variation in its receptor recruitment in vivo. Although TGF-{beta}1 and TGF-{beta}3 bind and assemble their ternary complexes in a similar manner, their structural differences together with differences in the affinities and kinetics of their receptor binding may underlie their unique biological activities. Structural comparisons revealed that the receptor-ligand pairing in the TGF-{beta} superfamily is dictated by unique insertions, deletions, and disulfide bonds rather than amino acid conservation at the interface. The binding mode of T{beta}RII on TGF-{beta} is unique to TGF-{beta}s, whereas that of type II receptor for bone morphogenetic protein on bone morphogenetic protein appears common to all other cytokines in the superfamily. Further, extensive hydrogen bonds and salt bridges are present at the high affinity cytokine-receptor interfaces, whereas hydrophobic interactions dominate the low affinity receptor-ligand interfaces.

  20. Crystallization and preliminary X-ray diffraction analysis of the ternary human GM-CSF receptor complex

    SciTech Connect

    Hansen, Guido; Hercus, Timothy R.; Xu, Yibin; Lopez, Angel F.; Parker, Michael W.; McKinstry, William J.

    2008-07-28

    Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a haemopoietic growth factor that acts through a ternary receptor signalling complex containing specific {alpha} (GMR{alpha}) and common {beta} ({beta}c) receptor subunits. Human GM-CSF is encoded by the gene csf2, while the genes for GMR{alpha} and {beta}c are csf2ra and csf2rb, respectively. Crystals of the ternary ectodomain complex comprising GM-CSF and the soluble extracellular regions of both the GMR{alpha} subunit and either {beta}c or its glutamine-substitution mutant N346Q were obtained using the hanging-drop vapour-diffusion method. The best diffracting crystals of the ternary complex were obtained using the N346Q mutation of the {beta}c subunit. These crystals grew using polyethylene glycol 3350 with a high concentration of proline, belonged to space group P6{sub 3}22 and diffracted to 3.3 {angstrom} resolution.

  1. The Arabidopsis glutamyl-tRNA reductase (GluTR) forms a ternary complex with FLU and GluTR-binding protein

    PubMed Central

    Fang, Ying; Zhao, Shun; Zhang, Feilong; Zhao, Aiguo; Zhang, Wenxia; Zhang, Min; Liu, Lin

    2016-01-01

    Tetrapyrrole biosynthesis is an essential and tightly regulated process, and glutamyl-tRNA reductase (GluTR) is a key target for multiple regulatory factors at the post-translational level. By binding to the thylakoid membrane protein FLUORESCENT (FLU) or the soluble stromal GluTR-binding protein (GBP), the activity of GluTR is down- or up-regulated. Here, we reconstructed a ternary complex composed of the C-terminal tetratricopepetide-repeat domain of FLU, GBP, and GluTR, crystallized and solved the structure of the complex at 3.2 Å. The overall structure resembles the shape of merged two binary complexes as previously reported, and shows a large conformational change within GluTR. We also demonstrated that GluTR binds tightly with GBP but does not bind to GSAM under the same condition. These findings allow us to suggest a biological role of the ternary complex for the regulation of plant GluTR. PMID:26794057

  2. The Arabidopsis glutamyl-tRNA reductase (GluTR) forms a ternary complex with FLU and GluTR-binding protein.

    PubMed

    Fang, Ying; Zhao, Shun; Zhang, Feilong; Zhao, Aiguo; Zhang, Wenxia; Zhang, Min; Liu, Lin

    2016-01-01

    Tetrapyrrole biosynthesis is an essential and tightly regulated process, and glutamyl-tRNA reductase (GluTR) is a key target for multiple regulatory factors at the post-translational level. By binding to the thylakoid membrane protein FLUORESCENT (FLU) or the soluble stromal GluTR-binding protein (GBP), the activity of GluTR is down- or up-regulated. Here, we reconstructed a ternary complex composed of the C-terminal tetratricopepetide-repeat domain of FLU, GBP, and GluTR, crystallized and solved the structure of the complex at 3.2 Å. The overall structure resembles the shape of merged two binary complexes as previously reported, and shows a large conformational change within GluTR. We also demonstrated that GluTR binds tightly with GBP but does not bind to GSAM under the same condition. These findings allow us to suggest a biological role of the ternary complex for the regulation of plant GluTR. PMID:26794057

  3. 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.

  4. Characterization of rates of ring-flipping in trimethoprim in its ternary complexes with Lactobacillus casei dihydrofolate reductase and coenzyme analogues.

    PubMed

    Polshakov, V I; Birdsall, B; Feeney, J

    1999-11-30

    NMR measurements have been used to investigate rates of ring-flipping and the activation parameters for the trimethoxybenzyl ring of the antibacterial drug trimethoprim (TMP) bound to Lactobacillus casei dihydrofolate reductase (DHFR) for a series of ternary complexes formed with analogues of the coenzyme NADPH. Rates were obtained at several temperatures from line shape analyses ((13)C-edited HSQC (1)H spectra) and transfer of magnetization measurements (zz-HSQC) on complexes containing 3'-O-[(13)C]trimethoprim. Examination of the structures of the complexes indicates that ring-flipping can only be achieved following major conformational changes and transient fluctuations of the protein and coenzyme structure around the trimethoxybenzyl ring. There is no simple correlation between rates of ring-flipping and binding constants. The presence of the coenzyme nicotinamide ring (in either its reduced or its oxidized forms) in the binding site close to the trimethoxybenzyl ring moiety is the major factor reducing the ring-flipping on coenzyme binding. Thus, the ternary complex with NADPH shows the largest reduction in the rate of ring-flipping (11 +/- 3 s(-)(1) at 298 K) as compared with the binary complex (793 +/- 80 s(-)(1) at 298 K). Complexes with NADPH analogues that either have no nicotinamide ring or are known to have their nicotinamide rings removed from the binding site show the smallest reductions. For the DHFR.TMP.NADP(+) complex where there are two conformations present, very different rates of ring-flipping were observed for the two forms. The activation parameters (DeltaH() and DeltaS()) for the ring-flipping in all the complexes are discussed in terms of the protein-ligand interactions and the possible constraints on the pathway through the transition state. PMID:10625463

  5. 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

  6. Ternary complex formation and competition quench fluorescence of ZnAF family zinc sensors.

    PubMed

    Staszewska, Anna; Kurowska, Ewa; Bal, Wojciech

    2013-11-01

    Our current understanding of the intracellular thermodynamics and kinetics of Zn(ii) ions is largely based on the application of fluorescent sensor molecules, used to study and visualize the concentration, distribution and transport of Zn(ii) ions in real time. Such agents are designed for high selectivity for zinc in respect to other biological metal ions. However, the issue of their sensitivity to physiological levels of low molecular weight Zn(ii) ligands (LMWLs) has not been addressed. We followed the effects of eight such compounds on the fluorescence of ZnAF-1 and ZnAF-2F, two representatives of the ZnAF family of fluorescein-based zinc sensors containing the N,N-bis(2-pyridylmethyl)ethylenediamine chelating unit. Fluorescence titrations of equimolar Zn(ii)-ZnAF-1 and Zn(ii)-ZnAF-2F solutions with acetate, phosphate, citrate, glycine, glutamic acid, histidine, ATP and GSH demonstrated strong fluorescence quenching. These results are interpreted in terms of an interplay of the formation of the [ZnAF-Zn(ii)-LMWL] ternary complexes and the competition for Zn(ii) between ZnAF and LMWLs. UV-vis spectroscopic titrations revealed the existence of supramolecular interactions between the fluorescein moiety of ZnAF-1 and ATP and His, which, however, did not contribute to fluorescence quenching. Therefore, the obtained results show that the ZnAF sensors, other currently used zinc sensors containing the N,N-bis(2-pyridylmethyl)ethylenediamine unit, and, in general, all sensors that do not saturate the Zn(ii) coordination sphere may co-report cellular metabolites and Zn(ii) ions, leading to misrepresentations of the concentrations and fluxes of biological zinc. PMID:23939683

  7. Nucleic acid interaction and antibacterial behaviours of a ternary palladium(II) complexes

    NASA Astrophysics Data System (ADS)

    Patel, Mohan N.; Dosi, Promise A.; Bhatt, Bhupesh S.

    2012-02-01

    The bidentate ligands and Pd(II) complexes have been synthesized and characterized using elemental analysis (C, H, N), 1H NMR, 13C NMR, electronic spectra, FT-IR and FAB mass spectroscopy. The binding of palladium complexes with calf thymus DNA (CT DNA) has been explored using absorption titration, DNA melting temperature and viscosity measurements. The cleavage reaction on pUC19 DNA has been monitored by agarose gel electrophoresis. The results suggest that complexes can bind to DNA by intercalative modes and exhibit nuclease activities in which supercoil form is converted to open circular form. The antibacterial activity of ligands and complexes has been performed against three Gram(-ve) and two Gram(+ve) microorganisms and the study indicates that all the complexes show better microbial inhibition activity than ligands and palladium salt.

  8. 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. PMID:25372632

  9. 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. PMID:25912408

  10. An engineered genetic selection for ternary protein complexes inspired by a natural three-component hitchhiker mechanism

    PubMed Central

    Lee, Hyeon-Cheol; Portnoff, Alyse D.; Rocco, Mark A.; DeLisa, Matthew P.

    2014-01-01

    The bacterial twin-arginine translocation (Tat) pathway is well known to translocate correctly folded monomeric and dimeric proteins across the tightly sealed cytoplasmic membrane. We identified a naturally occurring heterotrimer, the Escherichia coli aldehyde oxidoreductase PaoABC, that is co-translocated by the Tat translocase according to a ternary “hitchhiker” mechanism. Specifically, the PaoB and PaoC subunits, each devoid of export signals, are escorted to the periplasm in a piggyback fashion by the Tat signal peptide-containing subunit PaoA. Moreover, export of PaoA was blocked when either PaoB or PaoC was absent, revealing a surprising interdependence for export that is not seen for classical secretory proteins. Inspired by this observation, we created a bacterial three-hybrid selection system that links the formation of ternary protein complexes with antibiotic resistance. As proof-of-concept, a bispecific antibody was employed as an adaptor that physically crosslinked one antigen fused to a Tat export signal with a second antigen fused to TEM-1 β-lactamase (Bla). The resulting non-covalent heterotrimer was exported in a Tat-dependent manner, delivering Bla to the periplasm where it hydrolyzed β-lactam antibiotics. Collectively, these results highlight the remarkable flexibility of the Tat system and its potential for studying and engineering ternary protein interactions in living bacteria. PMID:25531212

  11. Structural Analysis of a Holoenzyme Complex of Mouse Dihydrofolate Reductase With NADPH And a Ternary Complex With the Potent And Selective Inhibitor 2,4-Diamino-6-(2'-Hydroxydibenz[b,F]azepin-5-YI)

    SciTech Connect

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

    2009-05-12

    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 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{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.

  12. A new ternary copper(II) complex derived from 2-(2'-pyridyl)benzimidazole and glycylglycine: synthesis, characterization, DNA binding and cleavage, antioxidation and HSA interaction.

    PubMed

    Fu, Xia-Bing; Lin, Zi-Hua; Liu, Hai-Feng; Le, Xue-Yi

    2014-03-25

    A new ternary copper(II)-dipeptide complex [Cu(glygly)(HPB)(Cl)]⋅2H2O (glygly=glycylglycine anion, HPB=2-(2'-pyridyl)benzimidazole) has been synthesized and characterized. The DNA interaction of the complex was studied by spectroscopic methods, viscosity, and electrophoresis measurements. The antioxidant activity was also investigated using the pyrogallol autoxidation assay. Besides, the interaction of the complex with human serum albumin (HSA) in vitro was examined by multispectroscopic techniques. The complex partially intercalated to CT-DNA with a high binding constant (Kb=7.28×10(5) M(-1)), and cleaved pBR322 DNA efficiently via an oxidative mechanism in the presence of Vc, with the HO· and O2(-) as the active species, and the SOD as a promoter. Furthermore, the complex shows a considerable SOD-like activity with the IC50 value of 3.8386 μM. The complex exhibits desired binding affinity to HSA, in which hydrogen bond or vander Waals force played a major role. The alterations of HSA secondary structure induced by the complex were confirmed by UV-visible, CD, synchronous fluorescence and 3D fluorescence spectroscopy. PMID:24291450

  13. A new ternary copper(II) complex derived from 2-(2";-pyridyl)benzimidazole and glycylglycine: Synthesis, characterization, DNA binding and cleavage, antioxidation and HSA interaction

    NASA Astrophysics Data System (ADS)

    Fu, Xia-Bing; Lin, Zi-Hua; Liu, Hai-Feng; Le, Xue-Yi

    2014-03-01

    A new ternary copper(II)-dipeptide complex [Cu(glygly)(HPB)(Cl)]ṡ2H2O (glygly = glycylglycine anion, HPB = 2-(2";-pyridyl)benzimidazole) has been synthesized and characterized. The DNA interaction of the complex was studied by spectroscopic methods, viscosity, and electrophoresis measurements. The antioxidant activity was also investigated using the pyrogallol autoxidation assay. Besides, the interaction of the complex with human serum albumin (HSA) in vitro was examined by multispectroscopic techniques. The complex partially intercalated to CT-DNA with a high binding constant (Kb = 7.28 × 105 M-1), and cleaved pBR322 DNA efficiently via an oxidative mechanism in the presence of Vc, with the HO· and O2-rad as the active species, and the SOD as a promoter. Furthermore, the complex shows a considerable SOD-like activity with the IC50 value of 3.8386 μM. The complex exhibits desired binding affinity to HSA, in which hydrogen bond or vander Waals force played a major role. The alterations of HSA secondary structure induced by the complex were confirmed by UV-visible, CD, synchronous fluorescence and 3D fluorescence spectroscopy.

  14. Formation of a ternary neptunyl(V) biscarbonato inner-sphere sorption complex inhibits calcite growth rate.

    PubMed

    Heberling, Frank; Scheinost, Andreas C; Bosbach, Dirk

    2011-06-01

    Neptunyl, Np(V)O(2)(+), along with the other actinyl ions U(VI)O(2)(2+) and Pu(V,VI)O(2)((+,2+)), is considered to be highly mobile in the geosphere, while interaction with mineral surfaces (inner- or outer-sphere adsorption, ion-exchange, and coprecipitation/structural incorporation) may retard its migration. Detailed information about the exact interaction mechanisms including the structure and stoichiometry of the adsorption complexes is crucial to predict the retention behavior in diverse geochemical environments. Here, we investigated the structure of the neptunyl adsorption complex at the calcite-water interface at pH 8.3 in equilibrium with air by means of low-temperature (15K) EXAFS spectroscopy at the Np-L(III) edge. The coordination environment of neptunyl consists of two axial oxygen atoms at 1.87(±0.01)Å, and an equatorial oxygen shell of six atoms at 2.51(±0.01)Å. Two oxygen backscatterers at 3.50(±0.04)Å along with calcium backscatterers at 3.95(±0.03)Å suggest that neptunyl is linked to the calcite surface through two monodentate bonds towards carbonate groups of the calcite surface. Two additional carbon backscatterers at 2.94(±0.02)Å are attributed to two carbonate ions in bidentate coordination. This structural environment is conclusively interpreted as a ternary surface complex, where a neptunyl biscarbonato complex sorbs through two monodentate carbonate bonds to steps at the calcite (104) face, while the two bidentately coordinated carbonate groups point away from the surface. This structural information is further supported by Mixed Flow Reactor (MFR) experiments. They show a significant decrease of the calcite growth rate in the presence of neptunyl(V), in line with blockage of the most active crystal growth sites, step and kink sites, by adsorption of neptunyl. Formation of this sorption complex constitutes an important retention mechanism for neptunyl in calcite-rich environments. PMID:21429616

  15. Review: Formation of Peptide Radical Ions Through Dissociative Electron Transfer in Ternary Metal-Ligand-Peptide Complexes

    SciTech Connect

    Chu, Ivan K.; Laskin, Julia

    2011-12-31

    The formation and fragmentation of odd-electron ions of peptides and proteins is of interest to applications in biological mass spectrometry. Gas-phase redox chemistry occurring during collision-induced dissociation of ternary metal-ligand-peptide complexes enables the formation of a variety of peptide radicals including the canonical radical cations, M{sup +{sm_bullet}}, radical dications, [M{sup +}H]{sup 2+{sm_bullet}}, radical anions, [M-2H]{sup -{sm_bullet}}. In addition, odd-electron peptide ions with well-defined initial location of the radical site are produced through side chain losses from the radical ions. Subsequent fragmentation of these species provides information on the role of charge and the location of the radical site on the competition between radical-induced and proton-driven fragmentation of odd-electron peptide ions. This account summarizes current understanding of the factors that control the efficiency of the intramolecular electron transfer (ET) in ternary metal-ligand-peptide complexes resulting in formation of odd-electron peptide ions. Specifically, we discuss the effect of the metal center, the ligand and the peptide structure on the competition between the ET, proton transfer (PT), and loss of neutral peptide and neutral peptide fragments from the complex. Fundamental studies of the structures, stabilities, and the energetics and dynamics of fragmentation of such complexes are also important for detailed molecular-level understanding of photosynthesis and respiration in biological systems.

  16. Separation of Metal Complexes with Counter Ions by Tube Radial Distribution Chromatography Using a Ternary Solvent Containing 8-quinolinol.

    PubMed

    Kawai, Yuji; Fujinaga, Satoshi; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

    2015-01-01

    An open-tubular capillary chromatography system (tube radial distribution chromatography, TRDC) was developed using a ternary solvent (water-acetonitrile-ethyl acetate; volume ratio, 3:8:4) containing 10 mmol L(-1) 8-quinolinol for the separation of nitrate, chloride, and sulfate compounds of Ni(II), Al(III), and Fe(III). When a mixed solution of the Ni(II) compounds was injected into an untreated fused-silica capillary tube (90 cm × 75 μm i.d.) with a ternary solvent flow rate of 0.8 μL min(-1), the compounds were eluted in the following order: [Ni(II)-(8-quinolinol)3] complex, [Ni(II)-(8-quinolinol)]-nitrate ion interaction complex, [Ni(II)-(8-quinolinol)]-chloride ion interaction complex, and [Ni(II)-(8-quinolinol)]-sulfate ion interaction complex. The elution of mixtures of the Al(III) and Fe(III) compounds showed similar trends. PMID:26561263

  17. Crystal structures of the HypCD complex and the HypCDE ternary complex: transient intermediate complexes during [NiFe] hydrogenase maturation.

    PubMed

    Watanabe, Satoshi; Matsumi, Rie; Atomi, Haruyuki; Imanaka, Tadayuki; Miki, Kunio

    2012-12-01

    [NiFe] hydrogenase maturation represents one of the most dynamic and sophisticated processes in metallocenter assembly. The Fe(CN)(2)CO moiety of [NiFe] hydrogenases is assembled via unknown transient interactions among specific maturation proteins HypC (metallochaperone), HypD (redox protein), and HypE (cyanide synthesis/donor). Here, we report the structures of the HypC-HypD and HypC-HypD-HypE complexes, providing a view of the transient interactions that take place during the maturation process. HypC binds to the conserved region of HypD through extensive hydrophobic interactions. The ternary complex formation between HypE and the HypCD complex involves both HypC and HypD, rendering the HypE conformation favorable for cyanide transfer. In the complex, the conserved cysteines of HypC and HypD form an Fe binding site. The conserved C-terminal cysteine of HypE can access the thiol redox cascade of HypD. These results provide structural insights into the Fe atom cyanation in the HypCDE complex. PMID:23123111

  18. 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

  19. Ternatin and improved synthetic variants kill cancer cells by targeting the elongation factor-1A ternary complex

    PubMed Central

    Carelli, Jordan D; Sethofer, Steven G; Smith, Geoffrey A; Miller, Howard R; Simard, Jillian L; Merrick, William C; Jain, Rishi K; Ross, Nathan T; Taunton, Jack

    2015-01-01

    Cyclic peptide natural products have evolved to exploit diverse protein targets, many of which control essential cellular processes. Inspired by a series of cyclic peptides with partially elucidated structures, we designed synthetic variants of ternatin, a cytotoxic and anti-adipogenic natural product whose molecular mode of action was unknown. The new ternatin variants are cytotoxic toward cancer cells, with up to 500-fold greater potency than ternatin itself. Using a ternatin photo-affinity probe, we identify the translation elongation factor-1A ternary complex (eEF1A·GTP·aminoacyl-tRNA) as a specific target and demonstrate competitive binding by the unrelated natural products, didemnin and cytotrienin. Mutations in domain III of eEF1A prevent ternatin binding and confer resistance to its cytotoxic effects, implicating the adjacent hydrophobic surface as a functional hot spot for eEF1A modulation. We conclude that the eukaryotic elongation factor-1A and its ternary complex with GTP and aminoacyl-tRNA are common targets for the evolution of cytotoxic natural products. DOI: http://dx.doi.org/10.7554/eLife.10222.001 PMID:26651998

  20. Foxo3 circular RNA retards cell cycle progression via forming ternary complexes with p21 and CDK2

    PubMed Central

    Du, William W.; Yang, Weining; Liu, Elizabeth; Yang, Zhenguo; Dhaliwal, Preet; Yang, Burton B.

    2016-01-01

    Most RNAs generated by the human genome have no protein-coding ability and are termed non-coding RNAs. Among these include circular RNAs, which include exonic circular RNAs (circRNA), mainly found in the cytoplasm, and intronic RNAs (ciRNA), predominantly detected in the nucleus. The biological functions of circular RNAs remain largely unknown, although ciRNAs have been reported to promote gene transcription, while circRNAs may function as microRNA sponges. We demonstrate that the circular RNA circ-Foxo3 was highly expressed in non-cancer cells and were associated with cell cycle progression. Silencing endogenous circ-Foxo3 promoted cell proliferation. Ectopic expression of circ-Foxo3 repressed cell cycle progression by binding to the cell cycle proteins cyclin-dependent kinase 2 (also known as cell division protein kinase 2 or CDK2) and cyclin-dependent kinase inhibitor 1 (or p21), resulting in the formation of a ternary complex. Normally, CDK2 interacts with cyclin A and cyclin E to facilitate cell cycle entry, while p21works to inhibit these interactions and arrest cell cycle progression. The formation of this circ-Foxo3-p21-CDK2 ternary complex arrested the function of CDK2 and blocked cell cycle progression. PMID:26861625

  1. Ternary complex formation between MADS-box transcription factors and the histone fold protein NF-YB.

    PubMed

    Masiero, Simona; Imbriano, Carol; Ravasio, Federica; Favaro, Rebecca; Pelucchi, Nilla; Gorla, Mirella Sari; Mantovani, Roberto; Colombo, Lucia; Kater, Martin M

    2002-07-19

    MADS-box proteins are transcription factors present in different eukaryotic kingdoms. In contrast to plants, for mammalian and yeast MADS-box proteins ternary complex formation with unrelated transcription factors was reported. We show here the first identification of such ternary interaction in plants. A rice seed-specific NF-YB was identified as partner of OsMADS18 by two-hybrid screening. NF-YB contains a histone fold motif, HFM,(1) and is part of the trimeric CCAAT-binding NF-Y complex. OsMADS18, alone or in combination with a natural partner, interacts with OsNF-YB1 through the MADS and I regions. The mouse NF-YB also associates with OsMADS18 in vivo and in vitro as a NF-YB-NF-YC dimer. Other rice MADS-box proteins do not interact in these assays, indicating specificity for the interaction. OsNF-YB1 is capable of heterodimerizing with NF-YC, but not trimerizing with NF-YA, thus precluding CCAAT binding. Mutation of the variant Asp at position 99 of the HFM alpha2-helix into a conserved serine recovers the capacity to interact with NF-YA, but not with DNA. This is the first indication that members of the NF-YB family work through mechanisms independent of the CCAAT box. PMID:11971906

  2. Ternatin and improved synthetic variants kill cancer cells by targeting the elongation factor-1A ternary complex.

    PubMed

    Carelli, Jordan D; Sethofer, Steven G; Smith, Geoffrey A; Miller, Howard R; Simard, Jillian L; Merrick, William C; Jain, Rishi K; Ross, Nathan T; Taunton, Jack

    2015-01-01

    Cyclic peptide natural products have evolved to exploit diverse protein targets, many of which control essential cellular processes. Inspired by a series of cyclic peptides with partially elucidated structures, we designed synthetic variants of ternatin, a cytotoxic and anti-adipogenic natural product whose molecular mode of action was unknown. The new ternatin variants are cytotoxic toward cancer cells, with up to 500-fold greater potency than ternatin itself. Using a ternatin photo-affinity probe, we identify the translation elongation factor-1A ternary complex (eEF1A·GTP·aminoacyl-tRNA) as a specific target and demonstrate competitive binding by the unrelated natural products, didemnin and cytotrienin. Mutations in domain III of eEF1A prevent ternatin binding and confer resistance to its cytotoxic effects, implicating the adjacent hydrophobic surface as a functional hot spot for eEF1A modulation. We conclude that the eukaryotic elongation factor-1A and its ternary complex with GTP and aminoacyl-tRNA are common targets for the evolution of cytotoxic natural products. PMID:26651998

  3. A ternary Cu2O-Cu-CuO nanocomposite: a catalyst with intriguing activity.

    PubMed

    Sasmal, Anup Kumar; Dutta, Soumen; Pal, Tarasankar

    2016-02-21

    In this work, the syntheses of Cu2O as well as Cu(0) nanoparticle catalysts are presented. Copper acetate monohydrate produced two distinctly different catalyst particles with varying concentrations of hydrazine hydrate at room temperature without using any surfactant or support. Then both of them were employed separately for 4-nitrophenol reduction in aqueous solution in the presence of sodium borohydride at room temperature. To our surprise, it was noticed that the catalytic activity of Cu2O was much higher than that of the metal Cu(0) nanoparticles. We have confirmed the reason for the exceptionally high catalytic activity of cuprous oxide nanoparticles over other noble metal nanoparticles for 4-nitrophenol reduction. A plausible mechanism has been reported. The unusual activity of Cu2O nanoparticles in the reduction reaction has been observed because of the in situ generated ternary nanocomposite, Cu2O-Cu-CuO, which rapidly relays electrons and acts as a better catalyst. In this ternary composite, highly active in situ generated Cu(0) is proved to be responsible for the hydride transfer reaction. The mechanism of 4-nitrophenol reduction has been established from supporting TEM studies. To further support our proposition, we have prepared a compositionally similar Cu2O-Cu-CuO nanocomposite using Cu2O and sodium borohydride which however displayed lower rate of reduction than that of the in situ produced ternary nanocomposite. The evolution of isolated Cu(0) nanoparticles for 4-nitrophenol reduction from Cu2O under surfactant-free condition has also been taken into consideration. The synthetic procedures of cuprous oxide as well as its catalytic activity in the reduction of 4-nitrophenol are very convenient, fast, cost-effective, and easily operable in aqueous medium and were followed spectrophotometrically. Additionally, the Cu2O-catalyzed 4-nitrophenol reduction methodology was extended further to the reduction of electronically diverse nitroarenes. This

  4. The three-dimensional structure of the native ternary complex of bovine pancreatic procarboxypeptidase A with proproteinase E and chymotrypsinogen C.

    PubMed

    Gomis-Rüth, F X; Gómez, M; Bode, W; Huber, R; Avilés, F X

    1995-09-15

    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. PMID:7556081

  5. Does As(III) interact with Fe(II), Fe(III) and organic matter through ternary complexes?

    PubMed

    Catrouillet, Charlotte; Davranche, Mélanie; Dia, Aline; Bouhnik-Le Coz, Martine; Demangeat, Edwige; Gruau, Gérard

    2016-05-15

    Up until now, only a small number of studies have been dedicated to the binding processes of As(III) with organic matter (OM) via ionic Fe(III) bridges; none was interested in Fe (II). Complexation isotherms were carried out with As(III), Fe(II) or Fe(III) and Leonardite humic acid (HA). Although PHREEQC/Model VI, implemented with OM thiol groups, reproduced the experimental datasets with Fe(III), the poor fit between the experimental and modeled Fe(II) data suggested another binding mechanism for As(III) to OM. PHREEQC/Model VI was modified to take various possible As(III)-Fe(II)-OM ternary complex conformations into account. The complexation of As(III) as a mononuclear bidentate complex to a bidentate Fe(II)-HA complex was evidenced. However, the model needed to be improved since the distribution of the bidentate sites appeared to be unrealistic with regards to the published XAS data. In the presence of Fe(III), As(III) was bound to thiol groups which are more competitive with regards to the low density of formed Fe(III)-HA complexes. Based on the new data and previously published results, we propose a general scheme describing the various As(III)-Fe-MO complexes that are able to form in Fe and OM-rich waters. PMID:26939079

  6. Evidence That Ternary Complex (eIF2-GTP-tRNAiMet)–Deficient Preinitiation Complexes Are Core Constituents of Mammalian Stress Granules

    PubMed Central

    Kedersha, Nancy; Chen, Samantha; Gilks, Natalie; Li, Wei; Miller, Ira J.; Stahl, Joachim; Anderson, Paul

    2002-01-01

    Environmental stress-induced phosphorylation of eIF2α inhibits protein translation by reducing the availability of eIF2-GTP-tRNAiMet, the ternary complex that joins initiator tRNAMet to the 43S preinitiation complex. The resulting untranslated mRNA is dynamically routed to discrete cytoplasmic foci known as stress granules (SGs), a process requiring the related RNA-binding proteins TIA-1 and TIAR. SGs appear to be in equilibrium with polysomes, but the nature of this relationship is obscure. We now show that most components of the 48S preinitiation complex (i.e., small, but not large, ribosomal subunits, eIF3, eIF4E, eIF4G) are coordinately recruited to SGs in arsenite-stressed cells. In contrast, eIF2 is not a component of newly assembled SGs. Cells expressing a phosphomimetic mutant (S51D) of eIF2α assemble SGs of similar composition, confirming that the recruitment of these factors is a direct consequence of blocked translational initiation and not due to other effects of arsenite. Surprisingly, phospho-eIF2α is recruited to SGs that are disassembling in cells recovering from arsenite-induced stress. We discuss these results in the context of a translational checkpoint model wherein TIA and eIF2 are functional antagonists of translational initiation, and in which lack of ternary complex drives SG assembly. PMID:11809833

  7. Ternary complex formation of Ino2p-Ino4p transcription factors and Apl2p adaptin beta subunit in yeast.

    PubMed

    Nikawa, Jun-ichi; Yata, Masako; Motomura, Miki; Miyoshi, Nobutaka; Ueda, Tsuyoshi; Hisada, Daisuke

    2006-11-01

    Yeast Ino2p-Ino4p heterodimeric complex is well known as a transcriptional activator for the genes regulated by inositol and choline, such as the INO1 gene. Apl2p is a large subunit of the yeast adaptin complex, an adaptor complex required for the clathrin coat to bind to the membrane. We found that Ino2p, Ino4p, and Apl2p form a ternary complex. This interaction was initially observed in a yeast two-hybrid study and subsequently verified by co-immunoprecipitation. Ino2p and Ino4p bind to Apl2p in the same region of Apl2p, viz., at the middle part and the C-terminal part. Ino2p and Ino4p bind to Apl2p independently, but more strongly when both are present. Furthermore, a disruption of APL2 together with INO2 or INO4 rendered yeast cells sensitive to oxidative stress. INO2-APL2 double disruptants also showed growth inability in non-fermentable carbon sources, such as glycerol. These results indicate a genetic interaction between APL2, INO2 and INO4 and uncovere novel functions of the Ino2p-Ino4p-Apl2p complex in yeast. PMID:17090927

  8. 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. PMID:26091143

  9. Visualization and translocation of ternary Calcineurin-A/Calcineurin-B/Calmodulin-2 protein complexes by dual-color trimolecular fluorescence complementation.

    PubMed

    Offenborn, Jan Niklas; Waadt, Rainer; Kudla, Jörg

    2015-10-01

    Fluorescence complementation (FC) techniques are expedient for analyzing bimolecular protein-protein interactions. Here we aimed to develop a method for visualization of ternary protein complexes using dual-color trimolecular fluorescence complementation (TriFC). Dual-color TriFC combines protein fragments of mCherry and mVenus, in which a scaffold protein is bilaterally fused to C-terminal fragments of both fluorescent proteins and combined with potential interacting proteins fused to an N-terminal fluorescent protein fragment. For efficient visual verification of ternary complex formation, TriFC was combined with a cytoplasm to plasma membrane translocation assay. Modular vector sets were designed which are fully compatible with previously reported bimolecular fluorescence complementation (BiFC) vectors. As a proof-of-principle, the ternary complex formation of the PP2B protein phosphatase Calcineurin-A/Calcineurin-B with Calmodulin-2 was investigated in transiently transformed Nicotiana benthamiana leaf epidermal cells. The results indicate a Calcineurin-B-induced interaction of Calmodulin-2 with Calcineurin-A. TriFC and the translocation of TriFC complexes provide a novel tool to investigate ternary complex formations with the simplicity of a BiFC approach. The robustness of FC applications and the opportunity to quantify fluorescence complementation render this assay suitable for a broad range of interaction analyses. PMID:25919910

  10. Metal-assisted red light-induced DNA cleavage by ternary L-methionine copper(II) complexes of planar heterocyclic bases.

    PubMed

    Patra, Ashis K; Dhar, Shanta; Nethaji, Munirathinam; Chakravarty, Akhil R

    2005-03-01

    Ternary copper(II) complexes [Cu(l-met)B(Solv)](ClO4) (1-4), where B is a N,N-donor heterocyclic base like 2,2'-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 3) and dipyrido[3,2-a:2'],3'-c]phenazene (dppz, 4), are prepared and their DNA binding and photo-induced DNA cleavage activity studied (L-Hmet =L-methionine). Complex 2, structurally characterized by X-ray crystallography, shows a square pyramidal (4 + 1) coordination geometry in which the N,O-donor L-methionine and N,N-donor heterocyclic base bind at the basal plane and a solvent molecule is coordinated at the axial site. The complexes display a d-d band at approximately 600 nm in DMF and exhibit a cyclic voltammetric response due to the Cu(II)/Cu(I) couple near -0.1 V in DMF-Tris-HCl buffer. The complexes display significant binding propensity to the calf thymus DNA in the order: 4(dppz) > 3(dpq) > 2(phen> 1(bpy). Control cleavage experiments using pUC19 supercoiled DNA and distamycin suggest major groove binding for the dppz and minor groove binding for the other complexes. Complexes 2-4 show efficient DNA cleavage activity on UV (365 nm) or red light (632.8 nm) irradiation via a mechanistic pathway involving formation of singlet oxygen as the reactive species. The DNA cleavage activity of the dpq complex is found to be significantly more than its dppz and phen analogues. PMID:15726142

  11. 1H-NMR studies on the ternary complexes of rare-earth ions with thenoyltrifluoroacetone and polyethers in dichloromethane.

    PubMed

    Gagabe, Gene Frederick; Satoh, Keiichi; Sawada, Kiyoshi

    2009-07-28

    The structures of the ternary complexes of lanthanoid and yttrium (Ln3+)-thenoyltrifluoroacetonates (tta-) with polyether (POE) in organic phase were investigated by 1H-NMR spectroscopy, where the POEs are crown ethers (18-crown-6 and benzo-18-crown-6) and monodispersed linear polyethers (DEOn: HO-(CH2CH2O-)nC12H25, where n=4, 6, 8). The changes in chemical shift of methylene protons of POE by addition of the adduct complex [Ln(tta)3(POE)] were measured at various Ln3+-to-POE concentration ratios. Chemical shift changes for each proton of POE by the formation of [Ln(tta)3(POE)] were determined. Results revealed that oxygen atoms at the hydroxyl terminal of linear POE have higher tendency to coordinate to the metal ion in [Ln(tta)3] complex. Three (for La3+) or two (for Lu3+ or Y3+) oxygen atoms of the POE coordinate to the metal ion without substitution of tta- ligands to satisfy the metal ion's coordination number of nine or eight, respectively. In the case of 18-membered crown ether complexes, La3+ is incorporated inside the cavity of the POE, displacing one of the three tta- from the inner coordination sphere while the other two remain coordinated to the metal ion. On the other hand, for the adduct of Y3+ complex with crown ether, all three tta- ligands are directly coordinating to the metal ion. PMID:19587993

  12. The structure of the ternary Eg5–ADP–ispinesib complex

    SciTech Connect

    Talapatra, S. K. Schüttelkopf, A. W. Kozielski, F.

    2012-10-01

    The complex between the motor protein Eg5 and the phase II clinical candidate ispinesib provides insights into the mechanism of action of this important class of inhibitors. The human kinesin Eg5 is responsible for bipolar spindle formation during early mitosis. Inhibition of Eg5 triggers the formation of monoastral spindles, leading to mitotic arrest that eventually causes apoptosis. There is increasing evidence that Eg5 constitutes a potential drug target for the development of cancer chemotherapeutics. The most advanced Eg5-targeting agent is ispinesib, which exhibits potent antitumour activity and is currently in multiple phase II clinical trials. In this study, the crystal structure of the Eg5 motor domain in complex with ispinesib, supported by kinetic and thermodynamic binding data, is reported. Ispinesib occupies the same induced-fit pocket in Eg5 as other allosteric inhibitors, making extensive hydrophobic interactions with the protein. The data for the Eg5–ADP–ispinesib complex suffered from pseudo-merohedral twinning and revealed translational noncrystallographic symmetry, leading to challenges in data processing, space-group assignment and structure solution as well as in refinement. These complications may explain the lack of available structural information for this important agent and its analogues. The present structure represents the best interpretation of these data based on extensive data-reduction, structure-solution and refinement trials.

  13. Net, an Ets ternary complex transcription factor, is expressed in sites of vasculogenesis, angiogenesis, and chondrogenesis during mouse development.

    PubMed

    Ayadi, A; Suelves, M; Dollé, P; Wasylyk, B

    2001-04-01

    The Net gene encodes an Ets transcription factor belonging to the ternary complex factor subfamily. We studied Net expression during mouse development (E7.5-E18.5) by in situ hybridization. Net is expressed at E7.5-8.5 in developing vascular primordia, including the allantoic vessels, heart endocardium and dorsal aortae. Vascular endothelial cell expression persists throughout development. Additional sites of expression appear at E9.5-E10.5, especially in facial, branchial arch and distal limb-bud mesenchyme. Later, expression is most conspicuous in developing cartilage and becomes progressively restricted to perichondrium. Net expression during mouse development correlates with vasculogenesis, angiogenesis and cartilage ontogeny. PMID:11287193

  14. DABCO-metallopophyrin binding: Ternary complexes, host-guest chemistry, and the measurement of. pi. -. pi. interactions

    SciTech Connect

    Hunter, C.A.; Meah, M.N.; Sanders, J.K.M. )

    1990-07-18

    Transient ternary complexes of the general form metalloporphyrin-DABCO-metalloporphyrin are described and characterized by NMR spectroscopy: the protons of DABCO (1,4-diazobicyclo(2.2.2)octane) molecules sandwiched between two diamagnetic metalloporphyrins resonate around {minus}5 ppm. The same structural motif is shown to occur when DABCO binds within the cavity of cofacial metalloporphyrin dimers. The kinetics and thermodynamics of intracavity binding were measured by electronic and NMR spectroscopy and lead to an estimate of 48 {plus minus} 10 kJ mol{sup {minus}1} (11.5 {plus minus} 2.4 kcal mol{sup {minus}1}) for the enthalpy of the {pi}-{pi} interaction between two zinc porphyrin moieties. The mechanism of ligand exchange and isomer interconversion for one of the porphyrin dimers has also been elucidated.

  15. Identification of the major arsenic-binding protein in rat plasma as the ternary dimethylarsinous-hemoglobin-haptoglobin complex.

    PubMed

    Naranmandura, Hua; Suzuki, Kazuo T

    2008-03-01

    Chronic exposure to arsenic causes a wide range of diseases such as hyperkeratosis, cardiovascular diseases, and skin, lung, and bladder cancers, and millions of people are chronically exposed to arsenic worldwide. However, little is known about the mechanisms underlying these toxic actions. The metabolism of arsenic is essential for understanding the toxic actions. Here, we identified the major arsenic-binding protein (As-BP) in the plasma of rats after oral administration of arsenite by the use of two different HPLC columns, gel filtration and anion exchange ones, coupled with an inductively coupled argon plasma mass spectrometer (ICP MS). The molecular mass of the As-BP was estimated to be 90 kDa based on results using the former column, and arsenic bound to this protein only in the form of dimethylarsinous acid (DMA (III)) in the plasma in vivo. In addition, the purified As-BP was shown to consist of two different proteins, haptoglobin (Hp) of 37 kDa (three bands) and the hemoglobin (Hb) alpha chain of 14 kDa (single band), using sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS), respectively, suggesting that the As-BP was the ternary DMA (III)-Hb-Hp complex. To confirm the present observations, an arsenic-binding assay was carried out in vitro . Although DMA (III) bound directly to fresh rat plasma proteins, they were different from that identified in vivo. However, when a DMA (III)-exposed rat RBC lysate (DMA (III) binds to Hb in rat RBCs) was added to control rat plasma, a new arsenic peak increased at the expense of the arsenic-Hb one. Furthermore, this new arsenic peak was consistent with the As-BP identified in the plasma in vivo, suggesting that arsenic bound to Hb further binds to haptoglobin (Hp), forming the ternary As-Hb-Hp complex. PMID:18247522

  16. Design of phase-only, binary phase-only, and complex ternary matched filters with increased signal-to-noise ratios for colored noise

    NASA Technical Reports Server (NTRS)

    Kumar, B. V. K. V.; Juday, Richard D.

    1991-01-01

    An algorithm is provided for treating nonwhite additive noise in determining regions of support for phase-only filters, binary phase-only filters, and complex ternary matched filters. It is analytically shown to be optimal in the signal-to-noise ratio sense. It extends earlier research that assumed white noise.

  17. Visible-near-infrared luminescent lanthanide ternary complexes based on beta-diketonate using visible-light excitation.

    PubMed

    Sun, Lining; Qiu, Yannan; Liu, Tao; Feng, Jing; Deng, Wei; Shi, Liyi

    2015-11-01

    We used the synthesized dinaphthylmethane (Hdnm) ligand whose absorption extends to the visible-light wavelength, to prepare a family of ternary lanthanide complexes, named as [Ln(dnm)3 phen] (Ln = Sm, Nd, Yb, Er, Tm, Pr). The properties of these complexes were investigated by Fourier transform infrared (FT-IR) spectroscopy, diffuse reflectance (DR) spectroscopy, thermogravimetric analyses, and excitation and emission spectroscopy. Generally, excitation with visible light is much more advantageous than UV excitation. Importantly, upon excitation with visible light (401-460 nm), the complexes show characteristic visible (Sm(3+)) as well as near-infrared (Sm(3+), Nd(3+), Yb(3+), Er(3+), Tm(3+), Pr(3+)) luminescence of the corresponding lanthanide ions, attributed to the energy transfer from the ligands to the lanthanide ions, an antenna effect. Now, using these near-infrared luminescent lanthanide complexes, the luminescent spectral region from 800 to 1650 nm, can be covered completely, which is of particular interest for biomedical imaging applications, laser systems, and optical amplification applications. PMID:25691149

  18. Synthesis and characterization of binary and ternary complexes of Co(II), Ni(II), Cu(II) and Zn(II) ions based on 4-aminotoluene-3-sulfonic acid

    NASA Astrophysics Data System (ADS)

    Faheim, Abeer A.; Abdou, Safaa N.; Abd El-Wahab, Zeinab H.

    2013-03-01

    Salicylidene (4-aminotoluene-3-sulfonic acid) Schiff base ligand H2L, and its binary and ternary Co(II), Ni(II), Cu(II) and Zn(II) complexes using 8-hydroxyquinoline (8-HOqu) and 2-aminopyridine (2-Ampy) as secondary ligands have been synthesised and characterized via elemental analysis, spectral data (IR, 1H NMR, mass and solid reflectance), molar conductance, magnetic moment, TG-DSC measurements and XRPD analysis. Correlation of all spectroscopic data suggest that H2L ligand acts as monoanionic terdentate ligand with ONO sites coordinating to the metal ions via deprotonated phenolic-O, azomethine-N and sulfonate-O while 2-Ampy behaves as a neutral monodentate ligand via amino group-N and 8-HOqu behaves as a monoanionic bidentate ligand through the ring-N and deprotonated phenolic-O. The thermal behavior of these complexes shows that the coordinated water molecules were eliminated from the complexes at relatively higher temperatures than the hydrated water and there are two routes in removal of coordinated water molecules. All complexes have mononuclear structure and the tetrahedral, square planar or an octahedral geometry have been proposed. The ligand and its complexes have been screened for their antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella typhimurium, Candida albicans and Aspergillus fumigatus. Among the synthesised compounds, the binary and ternary Ni(II) complexes, (2, 8 and 10) and ternary Zn(II) complex, (12) were found to be very effective against Candida albicans and Bacillus subtilis than all other complexes with MICs of 2 and 8 μg/mL, respectively.

  19. Synthesis and characterization of binary and ternary complexes of Co(II), Ni(II), Cu(II) and Zn(II) ions based on 4-aminotoluene-3-sulfonic acid.

    PubMed

    Faheim, Abeer A; Abdou, Safaa N; Abd El-Wahab, Zeinab H

    2013-03-15

    Salicylidene (4-aminotoluene-3-sulfonic acid) Schiff base ligand H(2)L, and its binary and ternary Co(II), Ni(II), Cu(II) and Zn(II) complexes using 8-hydroxyquinoline (8-HOqu) and 2-aminopyridine (2-Ampy) as secondary ligands have been synthesised and characterized via elemental analysis, spectral data (IR, (1)H NMR, mass and solid reflectance), molar conductance, magnetic moment, TG-DSC measurements and XRPD analysis. Correlation of all spectroscopic data suggest that H(2)L ligand acts as monoanionic terdentate ligand with ONO sites coordinating to the metal ions via deprotonated phenolic-O, azomethine-N and sulfonate-O while 2-Ampy behaves as a neutral monodentate ligand via amino group-N and 8-HOqu behaves as a monoanionic bidentate ligand through the ring-N and deprotonated phenolic-O. The thermal behavior of these complexes shows that the coordinated water molecules were eliminated from the complexes at relatively higher temperatures than the hydrated water and there are two routes in removal of coordinated water molecules. All complexes have mononuclear structure and the tetrahedral, square planar or an octahedral geometry have been proposed. The ligand and its complexes have been screened for their antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella typhimurium, Candida albicans and Aspergillus fumigatus. Among the synthesised compounds, the binary and ternary Ni(II) complexes, (2, 8 and 10) and ternary Zn(II) complex, (12) were found to be very effective against Candida albicans and Bacillus subtilis than all other complexes with MICs of 2 and 8 μg/mL, respectively. PMID:23295217

  20. Effect of A and B Metal Ion Site Occupancy on Conformational Changes in an RB69 DNA Polymerase Ternary Complex

    PubMed Central

    Wang, Mina; Lee, Harold R.; Konigsberg, William

    2010-01-01

    Rapid chemical quench assays, as well as equilibrium and stopped-flow fluorescence experiments, were performed with an RB69 DNA polymerase (RB69 pol)–primer-template (P/T) complex containing 2-aminopurine (dAP) and a metal exchange-inert Rh(III) derivative of a deoxynucleoside triphosphate (Rh • dTTP). The objective was to determine the effect of catalytic metal ion (A site) occupancy on the affinity of an incoming Rh • dTTP for the RB69 pol–P/T binary complex and on the rate of the conformational change induced by Rh • dTTP binding. With Ca2+ in the A site, the affinity of the incoming Rh • dTTP for the RB69 pol–P/T binary complex and the conformational change rate can be determined in the absence of chemistry. When Mg2+ was added to a ternary complex containing Rh • dTTP opposite dAP, the templating base, nucleotidyl transfer occurred, but the rate of product formation was only one-tenth of that found with Mg • dTTP, as determined by rapid chemical quench assays. Rates of conformational change subsequent to formation of a ternary complex, in the absence of chemistry, were estimated from the rate of change in dAP fluorescence with an increase in the Rh • dTTP concentration. We have shown that there is an initial rapid quenching of dAP fluorescence followed by a second phase of dAP quenching, which has nearly the same rate as that of dTMP incorporation, as estimated from rapid chemical quench experiments. We have also demonstrated that the affinity of Rh • dTTP for occupancy of the B metal ion site is dependent on the presence of Ca2+. However, a saturating Rh • dTTP concentration in the absence of Ca2+ results in full quenching of dAP fluorescence, whereas a saturating Ca2+ concentration in the absence of Rh • dTTP gives only partial quenching of dAP fluorescence. The implications of these results for the mechanism of Fingers closing, metal ion binding, and base selectivity are discussed. PMID:19228037

  1. Formation of ternary complexes with MgATP: effects on the detection of Mg2+ in biological samples by bidentate fluorescent sensors.

    PubMed

    Schwartz, Sarina C; Pinto-Pacheco, Brismar; Pitteloud, Jean-Philippe; Buccella, Daniela

    2014-03-17

    Fluorescent indicators based on β-keto-acid bidentate coordination motifs display superior metal selectivity profiles compared to current o-aminophenol-N,N,O-triacetic acid (APTRA) based chelators for the study of biological magnesium. These low denticity chelators, however, may allow for the formation of ternary complexes with Mg(2+) and common ligands present in the cellular milieu. In this work, absorption, fluorescence, and NMR spectroscopy were employed to study the interaction of turn-on and ratiometric fluorescent indicators based on 4-oxo-4H-quinolizine-3-carboxylic acid with Mg(2+) and ATP, the most abundant chelator of biological magnesium, thus revealing the formation of ternary complexes under conditions relevant to fluorescence imaging. The formation of ternary species elicits comparable or greater optical changes than those attributed to the formation of binary complexes alone. Dissociation of the fluorescent indicators from both ternary and binary species have apparent equilibrium constants in the low millimolar range at pH 7 and 25 °C. These results suggest that these bidentate sensors are incapable of distinguishing between free Mg(2+) and MgATP based on ratio or intensity-based steady-state fluorescence measurements, thus posing challenges in the interpretation of results from fluorescence imaging of magnesium in nucleotide-rich biological samples. PMID:24593871

  2. Formation of Ternary Complexes with MgATP: Effects on the Detection of Mg2+ in Biological Samples by Bidentate Fluorescent Sensors

    PubMed Central

    2015-01-01

    Fluorescent indicators based on β-keto-acid bidentate coordination motifs display superior metal selectivity profiles compared to current o-aminophenol-N,N,O-triacetic acid (APTRA) based chelators for the study of biological magnesium. These low denticity chelators, however, may allow for the formation of ternary complexes with Mg2+ and common ligands present in the cellular milieu. In this work, absorption, fluorescence, and NMR spectroscopy were employed to study the interaction of turn-on and ratiometric fluorescent indicators based on 4-oxo-4H-quinolizine-3-carboxylic acid with Mg2+ and ATP, the most abundant chelator of biological magnesium, thus revealing the formation of ternary complexes under conditions relevant to fluorescence imaging. The formation of ternary species elicits comparable or greater optical changes than those attributed to the formation of binary complexes alone. Dissociation of the fluorescent indicators from both ternary and binary species have apparent equilibrium constants in the low millimolar range at pH 7 and 25 °C. These results suggest that these bidentate sensors are incapable of distinguishing between free Mg2+ and MgATP based on ratio or intensity-based steady-state fluorescence measurements, thus posing challenges in the interpretation of results from fluorescence imaging of magnesium in nucleotide-rich biological samples. PMID:24593871

  3. Cooperative heparin-mediated oligomerization of fibroblast growth factor-1 (FGF1) precedes recruitment of FGFR2 to ternary complexes.

    PubMed

    Brown, Alan; Robinson, Christopher J; Gallagher, John T; Blundell, Tom L

    2013-04-16

    Fibroblast growth factors (FGFs) utilize cell surface heparan sulfate as a coreceptor in the assembly of signaling complexes with FGF-receptors on the plasma membrane. Here we undertake a complete thermodynamic characterization of the assembly of the FGF signaling complex using isothermal titration calorimetry. Heparin fragments of defined length are used as chemical analogs of the sulfated domains of heparan sulfate and examined for their ability to oligomerize FGF1. Binding is modeled using the McGhee-von Hippel formalism for the cooperative binding of ligands to a monodimensional lattice. Oligomerization of FGFs on heparin is shown to be mediated by positive cooperativity (α = 6). Heparin octasaccharide is the shortest length capable of dimerizing FGF1 and on longer heparin chains FGF1 binds with a minimal footprint of 4.2 saccharide units. The thermodynamics and stoichiometry of the ternary complex suggest that in solution FGF1 binds to heparin in a trans-dimeric manner before FGFR recruitment. PMID:23601319

  4. Synthesis and luminescent properties of ternary complex Eu(UVA)3Phen in nano-TiO2

    NASA Astrophysics Data System (ADS)

    Lü, Yu-guang; Gong, Zhong-ping; Gao, Hong-bing; Zhou, Shu-jing; Lü, Kui-lin; Wang, Ying; A, Du; Du, Hao-ran; Zhang, Li; Zhang, Fu-jun

    2015-01-01

    By introducing 2-hydroxy-4-methoxy-benzophenone (UVA) and 1,10-phenanthroline (Phen) as the ligands, the ternary rare earth complex of Eu(UVA)3Phen is synthesized, and it is characterized by elemental analysis, mass spectra (MS) and infrared (IR) and ultraviolet (UV) spectroscopy. Results show that the Eu(III) in complex emits strong red luminescence when it is excited by UV light, and it has higher sensitized luminescent efficiency and longer lifetime. The organic-inorganic thin film of complex Eu(UVA)3Phen doped with nano-TiO2 is prepared, and the nano-TiO2 is used in the luminescence layer to change the luminescence property of Eu(UVA)3Phen. It is found that there is an efficient energy transfer process between ligands and metal ions. Moreover, in an indium tin oxide (ITO)/poly(N-vinylcar-bazole) (PVK)/Eu(UVA)3Phen/Al device, Eu3+ can be excited by intramolecular ligand-to-metal energy transfer process. The main peak of emission at 613 nm is attributed to 5D0→7F2 transition of the Eu3+, and this process results in the enhanced red emission.

  5. Binary and ternary new water soluble copper(II) complexes of L-tyrosine and substituted 1,10-phenanthrolines: Effect of substitution on DNA interactions and cytotoxicities

    NASA Astrophysics Data System (ADS)

    İnci, Duygu; Aydın, Rahmiye; Vatan, Özgür; Yılmaz, Dilek; Gençkal, Hasene Mutlu; Zorlu, Yunus; Cavaş, Tolga

    2015-06-01

    Binary and ternary water soluble copper(II) complexes - [Cu(nphen)2(H2O)](NO3)2·H2O (1), [Cu(phen)2(H2O)](NO3)2 (2), [Cu(nphen)(L-tyr)(H2O)]NO3·2H2O (3), [Cu(phen)(tyr)(H2O)] NO3·2H2O (4) - and diquarternary salts of nphen and phen (nphen = 5-nitro-1,10-phenanthroline, phen = 1,10-phenanthroline and tyr = L-tyrosine) have been synthesized and characterized by CHN analysis, 1H NMR, 13C NMR and IR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques. The CT-DNA binding properties of these compounds have been investigated by thermal denaturation measurements, absorption and emission spectroscopy. The supercoiled pUC19 plasmid DNA cleavage activity of these compounds has been explored by agarose gel electrophoresis. The cytotoxicity of these compounds against MCF-7, Caco-2, A549 cancer cells and BEAS-2B healthy cells was also studied by using XTT method. The complexes 1-4 exhibit significant high cytotoxicity with low IC50 values in compared with cisplatin. The effect of the substituents of phen and coordinated amino acid in the above complexes are presented and discussed.

  6. Binary and ternary new water soluble copper(II) complexes of l-tyrosine and substituted 1,10-phenanthrolines: effect of substitution on DNA interactions and cytotoxicities.

    PubMed

    İnci, Duygu; Aydın, Rahmiye; Vatan, Özgür; Yılmaz, Dilek; Gençkal, Hasene Mutlu; Zorlu, Yunus; Cavaş, Tolga

    2015-06-15

    Binary and ternary water soluble copper(II) complexes - [Cu(nphen)2(H2O)](NO3)2·H2O (1), [Cu(phen)2(H2O)](NO3)2 (2), [Cu(nphen)(l-tyr)(H2O)]NO3·2H2O (3), [Cu(phen)(tyr)(H2O)] NO3·2H2O (4) - and diquarternary salts of nphen and phen (nphen=5-nitro-1,10-phenanthroline, phen=1,10-phenanthroline and tyr=l-tyrosine) have been synthesized and characterized by CHN analysis, (1)H NMR, (13)C NMR and IR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques. The CT-DNA binding properties of these compounds have been investigated by thermal denaturation measurements, absorption and emission spectroscopy. The supercoiled pUC19 plasmid DNA cleavage activity of these compounds has been explored by agarose gel electrophoresis. The cytotoxicity of these compounds against MCF-7, Caco-2, A549 cancer cells and BEAS-2B healthy cells was also studied by using XTT method. The complexes 1-4 exhibit significant high cytotoxicity with low IC50 values in compared with cisplatin. The effect of the substituents of phen and coordinated amino acid in the above complexes are presented and discussed. PMID:25795604

  7. Formation constants of ternary complexes of some heavy metal ions with N-(2-acetamido)iminodiacetic acid and aliphatic or aromatic acids

    SciTech Connect

    Hamed, M.M.A.; Mahmoud, M.R. . Dept. of Chemistry); Saleh, M.B.; Ahmed, I.T. . Dept. of Chemistry)

    1994-07-01

    N-(2-Acetamido)iminodiacetic acid (H[sub 2]ADA) is considered as one of the biologically important ligands. It is used as a complexing agent in the field of metal ion buffers working at the physiological pH range. Furthermore, it is widely used as an analytical chelating agent for the spectrophotometric determination of metal ions. Solution equilibria of the ternary systems involving La(III), Y(III), Ce(III), and UO[sub 2][sup 2+], N-(2-acetamido)iminodiacetic acid, and some aliphatic or aromatic acids have been investigated potentiometrically. The formation of 1:1:1 mixed ligand complexes is inferred from the potentiometric titration curves. Formation constants of the different binary and ternary complexes formed in such systems were determined at 25 [+-] 0.1 C and [mu] = 0.1 mol dm[sup [minus]3] (KNO[sub 3]). It is deduced that the mixed ligand complexes are more stable than the corresponding binary complexes containing the aliphatic or aromatic acidate moiety. The order of stability of the binary and ternary complexes is investigated and discussed in terms of the nature of both the metal ion and the secondary ligand (aliphatic or aromatic acid).

  8. Determination of astemizole, terfenadine and flunarizine hydrochloride by ternary complex formation with eosin and lead(II).

    PubMed

    Kelani, K; Bebawy, L I; Abdel-Fattah, L

    1999-01-01

    A simple and sensitive spectrophotometric method has been established for the determination of astemizole(I), terfenadine(II) and flunarizine hydrochloride(III) based on ternary complex formation with eosin and lead(II). The method does not involve solvent extraction. The colour of the produced complex is measured at 547.5 nm for (I) and (III), while (II) is measured at 540.7 nm. Appropriate conditions were established for the colour reaction and for the eosin: Pb(II): drug ratio to obtain maximum sensitivity. Under the proposed conditions, the method is applicable over concentration range of 4.1-37.6, 11.8-47.2 and 2.4-19.1 microg x ml(-1) with mean percentage recovery of 99.20+/-0.63, 99.76+/-0.39 and 99.60+/-0.47% for (I), (II) and (III), respectively. The suggested method was applied for determination of (I), (II) and (III) in pharmaceutical preparations. Through the use of a non-ionic surfactant (methylcellulose), prior extraction of the drugs was unnecessary. The results obtained demonstrated that the method is equally accurate, precise and reproducible as the official or reported methods. For the purpose of enhancing the sensitivity, a fluorescence quenching method for determination of the studied drugs via ternary complex formation was also investigated. The detection limit for the studied drugs (I), (II) and (III) was 0.94-7.1 microg x ml(-1) with mean percentage recovery of 99.84+/-0.29, 99.24+/-0.36 and 99.34+/-0.26%, respectively. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by official or reference methods. Unlike other reported ion-pair techniques, the suggested methods have the advantage of being applicable for the determination of the three drugs in their pharmaceutical dosage forms without prior extraction. They are recommended for quality control and routine analysis where time, cost effectiveness and high specificity of analytical techniques are of great importance. PMID

  9. Synthesis of novel binary and ternary complexes derived from 1-(2-hydroxy benzoyl)-4-phenylthiosemicarbazide (L(1)) and 2,2'-dipyridyl (L(2)) with Co(II), Cu(II) and Zn(II) salts.

    PubMed

    Azhari, Shaker J; Mlahi, Mosaad R; Al-Asmy, Ahmed A; Mostafa, Mohsen M

    2015-02-01

    The complexes derived the reactions of 1-(2-hydroxybenzoyl)-4-phenylthiosemicarbazide (L(1)) with MX2 (M = Co(II), Cu(II) and Zn(II) ions; X = Cl(-) in case of Co(II) and Cu(II) ions, Cl(-) and Ac(-) in case of Zn(II)) in EtOH, were synthesized and characterized. The results suggested that the complexes have the general formulae, [Cu(L(1)-2H)(EtOH)(H2O)2]⋅H2O, [Co(L(1)-2H)(EtOH)(H2O)]⋅2H2O and [Zn(L(1)-2H)(EtOH)]. Also, the ternary complexes, derived from the reactions 2,2'-dipyridyl (L(2)) with the metals salts followed by adding a solution of the L(1) were synthesized and having the general formulae, [Cu2(L(2))(L(1)-2H)(H2O)(OH)2]⋅1/2H2O, [Co(L(2))(L(1)-2H)]⋅1.5EtOH⋅3H2O and [Zn(L(2))(L(1)-2H)]⋅EtOH. The binary and ternary complexes were characterized by elemental analyses, molar conductivities, spectral (IR, UV-Vis, (1)H-NMR and mass), thermal and magnetic measurements. The existence of OH group in the ternary complexes was confirmed by IR spectra. The amounts of solvent were determined from the results of TGA. The biological activity for the ligand and two complexes were tested against DNA. PMID:25440581

  10. SAPCD2 Controls Spindle Orientation and Asymmetric Divisions by Negatively Regulating the Gαi-LGN-NuMA Ternary Complex.

    PubMed

    Chiu, Catherine W N; Monat, Carine; Robitaille, Mélanie; Lacomme, Marine; Daulat, Avais M; Macleod, Graham; McNeill, Helen; Cayouette, Michel; Angers, Stéphane

    2016-01-11

    Control of cell-division orientation is integral to epithelial morphogenesis and asymmetric cell division. Proper spatiotemporal localization of the evolutionarily conserved Gαi-LGN-NuMA protein complex is critical for mitotic spindle orientation, but how this is achieved remains unclear. Here we identify Suppressor APC domain containing 2 (SAPCD2) as a previously unreported LGN-interacting protein. We show that SAPCD2 is essential to instruct planar mitotic spindle orientation in both epithelial cell cultures and mouse retinal progenitor cells in vivo. Loss of SAPCD2 randomizes spindle orientation, which in turn disrupts cyst morphogenesis in three-dimensional cultures, and triples the number of terminal asymmetric cell divisions in the developing retina. Mechanistically, we show that SAPCD2 negatively regulates the localization of LGN at the cell cortex, likely by competing with NuMA for its binding. These results uncover SAPCD2 as a key regulator of the ternary complex controlling spindle orientation during morphogenesis and asymmetric cell divisions. PMID:26766442

  11. Solvent effect on H-bond cooperativity factors in ternary complexes of methanol, octan-1-ol, 2,2,2-trifluoroethanol with some bases

    NASA Astrophysics Data System (ADS)

    Solomonov, Boris N.; Varfolomeev, Mikhail A.; Abaidullina, Dilyara I.

    2008-03-01

    Cooperative hydrogen bonds in ternary complexes (ROH) 2⋯B (ROH—alcohols; B—bases) formed in pure bases (B) and solutions in n-hexane, carbon tetrachloride, benzene and 1,2-dichloroethane were studied by FTIR spectroscopy. Based on the observations, the authors were able to propose an original method of evaluating solvent effects on cooperativity factors in the complexes. Frequencies of cooperative hydrogen bonds OH⋯B ( νb) were determined for ternary complexes of pyridine with aliphatic alcohols (methanol, octan-1-ol) and for 2,2,2-trifluoroethanol with three different bases (acetonitrile, diethyl ether, tetrahydrofuran). The solvent shifts of νb were found to correlate with an empirical thermochemical parameter of the solvent, SVW. The cooperativity factors were determined for the complexes (ROH) 2⋯B in all studied media. It has been found that the cooperativity factors are almost independent of the solvent. In addition, a method was proposed of estimating the frequencies and cooperativity factors for ternary complexes (ROH) 2⋯B in the gas phase. It has been found that in gas phase the cooperativity factors are practically the same as in condensed media.

  12. Fluorescence characteristic study of the ternary complex of fluoroquinolone antibiotics and cobalt (II) with ATP

    NASA Astrophysics Data System (ADS)

    Wu, Shuqing; Zhang, Wujuan; Chen, Xingguo; Hu, Zhide; Hooper, Martin; Hooper, Beveley; Zhao, Zhengfeng

    2001-05-01

    The results from the measurement of the fluorescence spectra of fluoroquinolone antibiotics including ofloxacin (OF), norfloxacin (NOR) and ciprofloxacin (CIP) complexed with cobalt (II) and ATP give information concerning the antibiotics-nucleotide interactions. From the fluorescence spectral data, it appears that the fluoroquinolone antibiotic cannot directly complex with ATP but indirectly complex with cobalt (II), which is playing an intermediary role. The interaction of fluoroquinolone antibiotic with the nucleotide occurs mainly through the phosphate group. The conclusion offers a more complete mechanism, which is important for understanding the interaction of these drugs with DNA.

  13. Ternary inclusion complex formation and stabilization of limaprost, a prostaglandin E1 derivative, in the presence of α- and β-cyclodextrins in the solid state.

    PubMed

    Inoue, Yasuo; Iohara, Daisuke; Sekiya, Noboru; Yamamoto, Masanobu; Ishida, Hiroyuki; Sakiyama, Yoko; Hirayama, Fumitoshi; Arima, Hidetoshi; Uekama, Kaneto

    2016-07-25

    Limaprost/α-cyclodextrin (CD)/β-CD ternary inclusion complex was prepared by freeze-drying a solution containing all three components. Under humid conditions, limaprost was more stable in the ternary α-/β-CD inclusion complex than in the binary α- or β-CD complex. Specifically, during storage at 30°C/75% relative humidity (R.H.) for 4 weeks, about 19% of limaprost degraded into 17S,20-dimethyl-trans-Δ(2)-prostaglandin A1 (referred as 11-deoxy-Δ(10)) in the β-CD complex, 8.1% degraded in the α-CD complex, and only 2.2% degraded in the α-/β-CD complex. The mechanism of limaprost stabilization in the presence of both CDs was investigated by Raman and solid-state NMR spectroscopy and powder X-ray diffractometry. The fast degradation of limaprost to 11-deoxy-Δ(10) in the β-CD complex was due to the rapid crystallization of β-CD from the complex, liberating the free amorphous drug, which is susceptible to degradation. The dissociation and crystallization of β-CD from the inclusion complex were suppressed by freeze-drying limaprost in the presence of both α- and β-CDs. In addition, the interaction between limaprost and the two CDs was reinforced by inclusion of different moieties of limaprost: α-CD predominantly included the alkyl ω-chain, whereas β-CD included the five-membered ring. Thus, a stable ternary inclusion complex was formed that included limaprost, maintaining the amorphous state of the complex and dramatically stabilizing the drug under humid conditions. PMID:27286633

  14. Synthesis, structure and luminescence property of the three ternary and quaternary europium complexes

    NASA Astrophysics Data System (ADS)

    Li, X.; Jin, L. P.; Zheng, X. J.; Lu, S. Z.; Zhang, J. H.

    2002-04-01

    Three binuclear europium complexes containing bidentate and tridentate bridging carboxylates with diimines, namely [Eu( m-MOBA) 2NO 3phen] 2, [Eu(2,3-DMOBA) 2NO 3phen] 2 and [Eu(2,3-DMOBA) 3bpy] 2 ( m-MOBA=3-methoxybenzoate, 2,3-DMOBA=2,3-dimethoxy-benzoate, phen=1,10-phenanthroline, bpy=2,2'-bipyridine), have been synthesized and characterized by X-ray diffraction. The two europium(III) ions in each dimer are bridged by the four carboxylato groups in which two of them are the bidentate bridging mode, and the other two the tridentate bridging mode. The crystallographic data and combination bands of infrared spectra of the [Eu( m-MOBA) 2NO 3phen] 2 and the [Eu(2,3-DMOBA) 2NO 3phen] 2 complexes show that the nitrato group is bidentate, and thus each europium(III) ion in the complexes is coordinated with seven oxygen atoms and two nitrogen atoms from phen, leading to a dimeric structure with coordination number 9. Excitation and emission spectra of the europium complexes were observed at 77 K. The 5D0→ 7FJ ( J=0-4) luminescence spectra show that the europium(III) ion site in the crystals of the three europium complexes has C1 symmetry. The slightly different chemical environments of the europium(III) ions in the [Eu(2,3-DMOBA) 3bpy] 2 complex is confirmed by its emission spectra.

  15. Synthesis, structure and thermal stability of ternary metal complexes based on polycarboxylate and N-heterocyclic ligands

    NASA Astrophysics Data System (ADS)

    Fang, Ming-Jin; Li, Ming-Xing; He, Xiang; Shao, Min; Pang, Wei; Zhu, Shou-Rong

    2009-03-01

    The reactions of metal salts with pyrazine-2,3-dicarboxylic acid (H 2pzdc), pyridine-2,5-dicarboxylic acid (H 2pydc), pyrazine-2,3,5,6-tetracarboxylic acid (H 4pztc), 4,4'-bipyridine (bipy) and 1,10-phenanthroline (phen) afforded four new ternary complexes, namely [Co 2(pzdc) 2(bipy)(H 2O) 2] n·3 nH 2O ( 1), [Zn 2(pzdc) 2(bipy)(H 2O) 2] n·3 nH 2O ( 2), [Co(pydc) 2(H 2O) 2](H 2bipy) ( 3) and [Cu 2(pztc)(phen) 2(H 2O) 2]·2HNO 3·2H 2O ( 4). The metal centers are all six-coordinated. Compounds 1 and 2 are 2D coordination polymers exhibiting wave-like polymeric networks. The 2D layers are stacked in an interpenetrating mode to form double-layered frameworks, which possess ˜8 Å×6 Å tunnels occupied by (H 2O) 6 clusters. Compound 3 is a mononuclear supramolecular compound in which 4,4'-bipyridine is protonated and acted as a cationic building block. Compound 4 is a centro-symmetric binuclear complex. Pztc 4- as a hexadentate ligand coordinates to two Cu(II) ions to form four chelating rings. Phen are arranged in an ABAB parallel fashion to form a supramolecular architecture incorporating HNO 3 lattice molecule. The thermal stabilities of 1- 4 and luminescence of zinc complex 2 were also investigated.

  16. Synthesis, characterization, and near-infrared luminescent properties of the ternary thulium complex covalently bonded to mesoporous MCM-41

    SciTech Connect

    Feng Jing; Song Shuyan; Xing Yan; Zhang Hongjie Li Zhefeng; Sun Lining; Guo Xianmin; Fan Weiqiang

    2009-03-15

    The crystal structure of a ternary Tm(DBM){sub 3}phen complex (DBM=dibenzoylmethane; phen=1, 10-phenanthroline) and the synthesis of hybrid mesoporous material in which the complex covalently bonded to mesoporous MCM-41 are reported. Crystal data: Tm(DBM){sub 3}phen C{sub 59}H{sub 47}N{sub 2}O{sub 7}Tm, monoclinic, P21/c, a=19.3216(12) A, b=10.6691(7) A, c=23.0165(15) A, {alpha}=90 deg., {beta}=91.6330(10) deg., {gamma}=90 deg., V=4742.8(5) A{sup 3}, Z=4. The properties of the Tm(DBM){sub 3}phen complex and the corresponding hybrid mesoporous material [Tm(DBM){sub 3}phen-MCM-41] have been studied. The results reveal that the Tm(DBM){sub 3}phen complex is successfully covalently bonded to MCM-41. Both Tm(DBM){sub 3}phen complex and Tm(DBM){sub 3}phen-MCM-41 display typical near-infrared (NIR) luminescence upon excitation at the maximum absorption of the ligands, which contributes to the efficient energy transfer from the ligands to the Tm{sup 3+} ion, an antenna effect. The full width at half maximum (FWHM) centered at 1474 nm in the emission spectrum of Tm(DBM){sub 3}phen-MCM-41 is 110 nm, which is the potential candidate of broadening amplification band from C band (1530-1560 nm) to S{sup +} band (1450-1480 nm) in optical area. - Graphical abstract: The crystal structure of Tm(DBM){sub 3}phen complex (DBM=dibenzoylmethane; phen=1, 10-phenanthroline). The complex is successfully covalently bonded to MCM-41 (Tm(DBM){sub 3}phen-MCM-41). After ligand-mediated excitation, the emission spectrum of Tm(DBM){sub 3}phen-MCM-41 shows the bands 802 and 1474 nm. The FWHM of the 1474-nm band for Tm(DBM){sub 3}phen-MCM-41 is 110 nm, such a broad spectrum enables a wide gain bandwidth for optical amplification.

  17. Ternary complex factors SAP-1 and Elk-1, but not net, are functionally equivalent in thymocyte development.

    PubMed

    Costello, Patrick; Nicolas, Robert; Willoughby, Jane; Wasylyk, Bohdan; Nordheim, Alfred; Treisman, Richard

    2010-07-15

    The ternary complex factors (TCFs; SAP-1, Elk-1, and Net) are serum response factor cofactors that share many functional properties and are coexpressed in many tissues. SAP-1, the predominant thymus TCF, is required for thymocyte positive selection. In this study, we assessed whether the different TCFs are functionally equivalent. Elk-1 deletion, but not the hypomorphic Net(delta) mutation, exacerbated the SAP-1 positive selection phenotype, but triply deficient thymocytes were no more defective than SAP-1(-/-) Elk-1(-/-) cells. Inactivation of the other TCFs did not affect SAP-1-independent processes, including beta-selection, regulatory T cell selection, and negative selection, although reduced marginal zone B cells were observed in SAP-1(-/-) Elk-1(-/-) animals. Ectopic expression of Elk-1, but not Net, rescued positive selection of SAP-1(-/-) thymocytes; thus, SAP-1 and Elk-1 are functionally equivalent in this system, and the SAP-1 null selection phenotype reflects only its high expression in the thymus. Array analysis of TCR-stimulated double-positive cells identified SAP-1-dependent inducible genes whose transcription was further impaired in SAP-1(-/-) Elk-1(-/-) cells; thus, these genes, which include Egr-1 and Egr-2, represent candidate mediators of positive selection. Chromatin immunoprecipitation revealed subtly different promoter targeting between the different TCFs. Ectopic expression of Egr-1 restored positive selection in SAP-1 null thymocytes, establishing it (and possibly other Egr family members) as the major effector for ERK-SAP-1 signaling in thymocyte positive selection. PMID:20554967

  18. The ternary complex factor Net/Elk-3 participates in the transcriptional response to hypoxia and regulates HIF-1 alpha.

    PubMed

    Gross, C; Dubois-Pot, H; Wasylyk, B

    2008-02-21

    The ternary complex factor Net/Elk3 is downregulated in hypoxia and participates in the induction by hypoxia of several genes, including c-fos, vascular endothelial growth factor and egr-1. However, the global role of Net in hypoxia remains to be elucidated. We have identified, in a large-scale analysis of RNA expression using microarrays, more than 370 genes that are regulated by Net in hypoxia. In order to gain insights into the role of Net in hypoxia, we have analysed in parallel the genes regulated by HIF-1alpha, the classical factor involved in the response to hypoxia. We identified about 190 genes that are regulated by HIF-1alpha in hypoxia. Surprisingly, when we compare the genes induced by hypoxia that require either Net or HIF-1alpha, the majority are the same (75%), suggesting that the functions of both factors are closely linked. Interestingly, in hypoxia, Net regulates the expression of several genes known to control HIF-1alpha stability, including PHD2, PHD3 and Siah2, suggesting that Net regulates the stability of HIF-1alpha. We found that inhibition of Net by RNAi leads to decreased HIF-1alpha expression at the protein level in hypoxia. These results indicate that Net participates in the transcriptional response to hypoxia by regulation of HIF-1alpha protein stability. PMID:17704799

  19. Hydrogen-Bonding Capability of a Templating Difluorotoluene Nucleotide Residue in an RB69 DNA Polymerase Ternary Complex

    SciTech Connect

    Xia, Shuangluo; Konigsberg, William H.; Wang, Jimin

    2011-08-29

    Results obtained using 2,4-difluorotoluene nucleobase (dF) as a nonpolar thymine isostere by Kool and colleagues challenged the Watson-Crick dogma that hydrogen bonds between complementary bases are an absolute requirement for accurate DNA replication. Here, we report crystal structure of an RB69 DNA polymerase L561A/S565G/Y567A triple mutant ternary complex with a templating dF opposite dTTP at 1.8 {angstrom}-resolution. In this structure, direct hydrogen bonds were observed between: (i) dF and the incoming dTTP, (ii) dF and residue G568 of the polymerase, and (iii) dF and ordered water molecules surrounding the nascent base pair. Therefore, this structure provides evidence that a templating dF can form novel hydrogen bonds with the incoming dTTP and with the enzyme that differ from those formed with a templating dT.

  20. Docking and molecular dynamics simulations of the ternary complex nisin2:lipid II

    PubMed Central

    Mulholland, Sam; Turpin, Eleanor R.; Bonev, Boyan B.; Hirst, Jonathan D.

    2016-01-01

    Lanthionine antibiotics are an important class of naturally-occurring antimicrobial peptides. The best-known, nisin, is a commercial food preservative. However, structural and mechanistic details on nisin-lipid II membrane complexes are currently lacking. Recently, we have developed empirical force-field parameters to model lantibiotics. Docking and molecular dynamics (MD) simulations have been used to study the nisin2:lipid II complex in bacterial membranes, which has been put forward as the building block of nisin/lipid II binary membrane pores. An Ile1Trp mutation of the N-terminus of nisin has been modelled and docked onto lipid II models; the computed binding affinity increased compared to wild-type. Wild-type nisin was also docked onto three different lipid II structures and a stable 2:1 nisin:lipid II complex formed. This complex was inserted into a membrane. Six independent MD simulations revealed key interactions in the complex, specifically the N-terminal engagement of nisin with lipid II at the pyrophosphate and C-terminus of the pentapeptide chain. Nisin2 inserts into the membrane and we propose this as the first step in pore formation, mediated by the nisin N-terminus–lipid II pentapeptide hydrogen bond. The lipid II undecaprenyl chain adopted different conformations in the presence of nisin, which may also have implications for pore formation. PMID:26888784

  1. Binary and ternary complexes of some inner transition metal ions with amino acids and acetyl acetone

    NASA Astrophysics Data System (ADS)

    Abu-Eittah, R. H.; Abdou, M. M.; Salem, M. B.

    1998-05-01

    The stability constants of the 1:1 and 1:2 (whenever possible) complexes formed between La3+, Ce3+, Th4+ and the amino acid anions L-alaninate, L-phenylalaninate and L-histidinate were determined by potentiometric titration in aqueous solution (25± 1 ^circC, I = 0.1 M KCl) and compared together with the constants previously determined. The various formation degree of the resulting M(L) and M(L)2 were determined. In order to relate the formation degree of M(L) and M(L)2 with the basicity of the amino acid anion (L^-), the acidity constants of the protonated amino acids, H2L^+, were also measured. The main results of this work prove that Th4+ ion forms the strongest complex with the studied amino acids. It is the only ion which forms a 1:2 complex. The heterocyclic ring of histidine plays a significant role in complexing with the studied metal ions as is clearly seen from the distribution of the degree of formation of the different complexes. The stability constants of the 1:1:1, 1:2:1 and 1:1:2 complexes formed between La3+, Ce3+, Th4+ and the anions L-alaninate, L-phenylalaninate and L-histidinate together with the acetyl acetonate ion were also determined following the same experimental set up used in the study of the simple complexes. The mixed-ligand complexes turned out to be very much stronger than the simple ligand complexes. Formation of a mixed ligand complex can be considered as a type of senergism. Les constantes de stabilité des complexes 1:1 et 2:2 (lorsque cela est possible) formés entre La3+, Ce3+, Th4+ et les anions aminoacides L-alaninate, L-phénylalaninate et L-histidinate ont été déterminées par dosage potentiométrique en solution aqueuse (25± 1 ^circC, I = 0,1 M KCl), et comparées à celles de la littérature. Les différents degrés de formation de M(L) et M(L)2 ont été quantifiés. Pour mettre en évidence la relation entre le degré de formation de M(L) et M(L)2 et la basicité des anions aminoacides (L^-), les constantes d

  2. A ternary tetracoordinated Pd II complex with metformin and dipicolinate: Synthesis, characterization and crystal structure

    NASA Astrophysics Data System (ADS)

    Moghimi, A.; Khavassi, H. R.; Dashtestani, F.; Kordestani, D.; Ekram Jafari, A.; Maddah, B.; Moosavi, S. M.

    2011-06-01

    A proton transfer compound L, (MetH) 2(dipic), (dipicH 2 = 2,6-pyridinedicarboxylic acid and Met = Metformin (N,N-dimethylebiguanidine), was synthesized and characterized by IR, 1H and 13C NMR spectroscopy. The reaction of L with PdCl 2 in water results in the formation of novel tetracoordinated Pd II complex [Pd(dipic)(Met)]·2H 2O indicating the participation of both dipic 2- and Met as chelating ligands. This complex was characterized by single crystal X-ray analysis. The crystal system is monoclinic with space group P2 1/c. The unit cell dimensions for Pd II complex 1 is a = 8.8619(14) Å, b = 9.5072(9) Å, c = 19.153(3) Å.

  3. Efficient Layers of Emitting Ternary Lanthanide Complexes for Fabricating Red, Green, and Yellow OLEDs.

    PubMed

    Ahmed, Zubair; Iftikhar, Khalid

    2015-12-01

    A series of novel nona- and octacoordinate highly volatile and luminescent complexes, [Eu(hfaa)3(indazole)3] and [Ln(hfaa)3(indazole)2] (Ln = Tb, Dy, and Lu), were synthesized using a monoanionic bidentate hexafluoroacetylacetone (hfaa(-)) and a neutral monodentate indazole ligand. The X-ray diffraction analyses of their single-crystals indicate that the complexes are mononuclear. The Eu complex is nonacoordinate and has a distorted monocapped square antiprismatic structure whereas the terbium and dysprosium complexes are octacoordinate and possess a trigonal bicapped prism geometry. The indazole units are involved in π-π stacking interaction and N-H···F hydrogen bonding with the fluorine atoms of hfaa(-). The photophysical studies of indazole and the complexes show that the triplet states are at the appropriate positions and make ligand-to-metal energy transfer process efficient. A strong protective shield is provided by the coordination of three hfaa(-) moieties (which have low frequency C-F vibrational oscillators), and two/three ancillary indazole ligands around these metal ions ascribe higher quantum yields and longer radiative life times (ΦEu = 69% ± 10, 989 ± 1 μs, ΦTb = 33% ± 10, 546 ± 1 μs, and ΦDy = 2.5% ± 10, 13.6 ± 1 μs) to these novel compounds. The emission from europium, terbium, and dysprosium are, respectively, red, green, and yellow. Finally, these compounds were used, as emitting layers, to fabricate electroluminescent devices of their respective colors. The best devices are found with the following structure: ITO/CuPc (15 nm)/[Eu complex]:CBP or [Tb complex]:CBP or [Dy complex]:CBP (80 nm)/BCP (25 nm)/AlQ (30 nm)/LiF (1 nm)/Al (100 nm), which indicates an improved EL performance for the Eu device over the Eu devices reported in the literature. The ligand, indazole, is a good sensitizer for trivalent europium, terbium, and dysprosium ions. It together with hfaa(-) plays an important role in fabricating OLEDs, especially

  4. Determination of vanadium as 4-(2-pyridylazo)resorcinol-hydrogen peroxide ternary complexes by ion-interaction reversed-phase liquid chromatography.

    PubMed

    Vachirapatama, Narumol; Dicinoski, Greg W; Townsend, Ashley T; Haddad, Paul R

    2002-05-17

    The separation and determination of the vanadium(V) ternary complex formed with 4-(2-pyridylazo)resorcinol (PAR) and hydrogen peroxide using ion-interaction reversed-phase high-performance liquid chromatography on a C18 column has been investigated. The optimal mobile phase was a methanol-water solution (32:68, v/v) containing 3 mM tetrabutylammonium bromide, 5 mM acetic acid and 5 mM citrate buffer at pH 7, with absorbance detection at 540 nm. The stoichiometry of the ternary complex of vanadium at pH 6 in 10 mM acetate buffer using the mole ratio and Job's method by HPLC indicated that the mole ratio of V(V):PAR:H2O2 was 1:1:1. The optimal conditions for precolumn formation of the ternary complex were 10 mM acetate, 7 mM H2O2, 0.3 mM PAR, and pH 6. The method gave relative standard deviations of retention time, peak area and peak height for the ternary complex of 0.187, 0.45 and 0.57%, respectively. The detection limit (at a signal-to-noise ratio of 3) for V(V) was 0.09 ng/ml in the digested sample using a 100-microl injection loop (or 0.09 microg/g in the solid fertiliser sample). The method was applied to the analysis of fertilisers (phosphate rocks and nitrogen, phosphorus and potassium fertiliser). The results for vanadium obtained by the HPLC method agreed well with those from magnetic sector inductively coupled plasma MS analysis. PMID:12108654

  5. Visualization of Subunit Interactions and Ternary Complexes of Protein Phosphatase 2A in Mammalian Cells

    PubMed Central

    Mo, Shu-Ting; Chiang, Shang-Ju; Lai, Tai-Yu; Cheng, Yu-Ling; Chung, Cheng-En; Kuo, Spencer C. H.; Reece, Kelie M.; Chen, Yung-Cheng; Chang, Nan-Shan; Wadzinski, Brian E.; Chiang, Chi-Wu

    2014-01-01

    Protein phosphatase 2A (PP2A) is a ubiquitous phospho-serine/threonine phosphatase that controls many diverse cellular functions. The predominant form of PP2A is a heterotrimeric holoenzyme consisting of a scaffolding A subunit, a variable regulatory B subunit, and a catalytic C subunit. The C subunit also associates with other interacting partners, such as α4, to form non-canonical PP2A complexes. We report visualization of PP2A complexes in mammalian cells. Bimolecular fluorescence complementation (BiFC) analysis of PP2A subunit interactions demonstrates that the B subunit plays a key role in directing the subcellular localization of PP2A, and confirms that the A subunit functions as a scaffold in recruiting the B and C subunits to form a heterotrimeric holoenzyme. BiFC analysis also reveals that α4 promotes formation of the AC core dimer. Furthermore, we demonstrate visualization of specific ABC holoenzymes in cells by combining BiFC and fluorescence resonance energy transfer (BiFC-FRET). Our studies not only provide direct imaging data to support previous biochemical observations on PP2A complexes, but also offer a promising approach for studying the spatiotemporal distribution of individual PP2A complexes in cells. PMID:25536081

  6. A comparative study of three ternary complexes prepared in different mixing orders of siRNA/redox-responsive hyperbranched poly (amido amine)/hyaluronic acid

    PubMed Central

    Chen, Cheng-Jun; Zhao, Zhi-Xia; Wang, Jian-Cheng; Zhao, En-Yu; Gao, Ling-Yan; Zhou, Shu-Feng; Liu, Xiao-Yan; Lu, Wan-Liang; Zhang, Qiang

    2012-01-01

    In this study, a novel redox-responsive hyperbranched poly(amido amine) (named PCD) was synthesized and used as a cationic polymer to form a ternary complex with small interfering RNA (siRNA) and hyaluronic acid (HA) for siRNA delivery. Here, it is hypothesized that different mixing orders result in different assembly structures, which may affect the siRNA delivery efficiency. To investigate the effects of mixing orders on siRNA delivery efficiency in two human breast cancer cell lines, three ternary complexes with different mixing orders of siRNA/PCD/HA were prepared and characterized: mixing order I (initially prepared siRNA/PCD binary complex further coated by negatively charged HA), mixing order II ( initially prepared HA/PCD binary complex further incubated with siRNA), and mixing order III ( initially prepared siRNA/HA mixture further electrostatically compacted by positively charged PCD). With an optimized siRNA/PCD/HA charge ratio of 1/20/16, the particle sizes and zeta potentials of these ternary complexes were 124.8 nm and 27.3 mV (mixing order I), 147.5 nm and 29.9 mV (mixing order II), and 128.8 nm and 19.4 mV (mixing order III). Also, the effects on stability, cellular uptake, and gene silencing efficiency of siRNA formulated in ternary complexes with different mixing orders were investigated. The results showed that mixing orders I and III displayed better siRNA transfection and protection than mixing order II in human breast cancer MCF-7 and MDA-MB-231 cells. More interesting, at the siRNA/PCD/HA charge ratio of 1/20/16, the gene silencing effects on vascular endothelial growth factor expression in MDA-MB- 231 cells were as follows: mixing order III > mixing order I > mixing order II. Based on these results, a likely explanation for the difference in functionality dependent on mixing orders is the formation of different assembly structures. These results may help future optimization of siRNA ternary complexes for achieving better delivery

  7. Tumor Acidity-Induced Sheddable Polyethylenimine-Poly(trimethylene carbonate)/DNA/Polyethylene Glycol-2,3-Dimethylmaleicanhydride Ternary Complex for Efficient and Safe Gene Delivery.

    PubMed

    Zhao, Caiyan; Shao, Leihou; Lu, Jianqing; Deng, Xiongwei; Wu, Yan

    2016-03-16

    Amphiphilic PEI derivatives/DNA complexes are widely used for DNA delivery, but they are unstable in vivo and have cytotoxicity due to the excess cationic charge. PEGylation of cationic complexes can improve sterical stability and biocompatibility. However, PEGylation significantly inhibits cellular uptake and endosomal escape. In this work, sheddable ternary complexes were developed by coating a tumor acidity-sensitive β-carboxylic amide functionalized PEG layer on the binary complexes of amphiphilic cationic polyethylenimine-poly(trimethylene carbonate) nanoparticles/DNA (PEI-PTMC/DNA). Such sheddable ternary complexes markedly reduced their nonspecific interactions with serum protein in the bloodstream and obtained minimal cytotoxicity due to the protection of the PEG shell. At the tumor site, the PEG layer was deshielded by responding to the tumor acidic microenvironment and the positively charged complexes re-exposed that had higher affinity with negatively charged cell membranes. Meanwhile the positively charged complexes facilitated endosomal escape. Accordingly, this delivery system improved the biocompatibility of gene-loaded complexes and enhanced the gene transfection efficiency. Such PEGylated complexes with the ability to deshield the PEG layer at the target tissues hold great promise for efficient and safe gene delivery in vivo. PMID:26904916

  8. 1,10-Phenanthroline promotes copper complexes into tumor cells and induces apoptosis by inhibiting the proteasome activity.

    PubMed

    Zhang, Zhen; Bi, Caifeng; Schmitt, Sara M; Fan, Yuhua; Dong, Lili; Zuo, Jian; Dou, Q Ping

    2012-12-01

    Indole-3-acetic acid and indole-3-propionic acid, two potent natural plant growth hormones, have attracted attention as promising prodrugs in cancer therapy. Copper is known to be a cofactor essential for tumor angiogenesis. We have previously reported that taurine, L-glutamine, and quinoline-2-carboxaldehyde Schiff base copper complexes inhibit cell proliferation and proteasome activity in human cancer cells. In the current study, we synthesized two types of copper complexes, dinuclear complexes and ternary complexes, to investigate whether a certain structure could easily carry copper into cancer cells and consequently inhibit tumor proteasome activity and induce apoptosis. We observed that ternary complexes binding with 1,10-phenanthroline are more potent proteasome inhibitors and apoptosis inducers than dinuclear complexes in PC-3 human prostate cancer cells. Furthermore, the ternary complexes potently inhibit proteasome activity before induction of apoptosis in MDA-MB-231 human breast cancer cells, but not in nontumorigenic MCF-10A cells. Our results suggest that copper complexes binding with 1,10-phenanthroline as the third ligand could serve as potent, selective proteasome inhibitors and apoptosis inducers in tumor cells, and that the ternary complexes may be good potential anticancer drugs. PMID:23053530

  9. Zirconia-based luminescent organic-inorganic hybrid materials with ternary europium (III) complexes bonded

    NASA Astrophysics Data System (ADS)

    Yang, Jing; Li, Zhiqiang; Xu, Yang; Wang, Yige

    2016-05-01

    In this work, a novel red-emitting organic-inorganic hybrid material with europium (III) lanthanide β-diketonate complexes linked to a zirconia was reported, which was realized by adduct formation with zirconia-tethered terpyridine moieties. Luminescence enhancement of the hybrid material has been observed compared with pure Eu(tta)3·2H2O. Transparent and strongly luminescent thin films based on PMMA were also prepared at room temperature, which are highly luminescent under UV-light irradiation and possess a promising prospect in the area of optics.

  10. Neutronics and activation analysis of lithium-based ternary alloys in IFE blankets

    DOE PAGESBeta

    Jolodosky, Alejandra; Kramer, Kevin; Meier, Wayne; DeMuth, James; Reyes, Susana; Fratoni, Massimiliano

    2016-04-09

    Here we report that an attractive feature of using liquid lithium as the breeder and coolant in fusion blankets is that it has very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and presents plant safety concerns. The Lawrence Livermore National Laboratory is carrying an effort to develop a lithium-based alloy that maintains the beneficial properties of lithium (e.g. high tritium breeding and solubility) and at the same time reduces overall flammability concerns. This study evaluates the neutronics performance of lithium-based alloys inmore » the blanket of an inertial fusion energy chamber in order to inform such development. 3-D Monte Carlo calculations were performed to evaluate two main neutronics performance parameters for the blanket: tritium breeding ratio (TBR), and the fusion energy multiplication factor (EMF). It was found that elements that exhibit low absorption cross sections and higher q-values such as lead, tin, and strontium, perform well with those that have high neutron multiplication such as lead and bismuth. These elements meet TBR constrains ranging from 1.02 to 1.1. However, most alloys do not reach EMFs greater than 1.15. Additionally, it was found that enriching lithium significantly increases the TBR and decreases the minimum lithium concentration by more than 60%. The amount of enrichment depends on how much total lithium is in the alloy to begin with. Alloys that performed well in the TBR and EMF calculations were considered for activation analysis. Activation simulations were executed with 50 years of irradiation and 300 years of cooling. It was discovered that bismuth is a poor choice due to achieving the highest decay heat, contact dose rates, and accident doses. In addition, it does not meet the waste disposal ratings (WDR). Some of the activation results for alloys with tin, zinc, and gallium were in

  11. Protein synthesis in brine shrimp embryos. Regulation of the formation of the ternary complex (Met-tRNAf X eIF-2 X GTP) by two purified protein factors and phosphorylation of Artemia eIF-2.

    PubMed

    Woodley, C L; Roychowdhury, M; MacRae, T H; Olsen, K W; Wahba, A J

    1981-07-01

    We have purified from the ribosomal wash of dormant and developing embryos of Artemia two proteins, Co-eIF-2(A) and Co-eIF-2(B). These factors are essential for ternary complex formation and binding of [35S]-Met-tRNAf to 40-S ribosomal subunits with 15-30 microgram eIF-2/ml of reaction mixture. On polyacrylamide gel electrophoresis in dodecylsulfate, Co-eIF-2(A) is composed of a single polypeptide of Mr 65 000, whereas Co-eIF-2(B) contains polypeptides of Mr 105000 and 112000. Co-eIF-2(A) is sensitive to 4.5 microM aurintricarboxylic acid but Co-eIF-2(B) requires approximately 15 microM aurintricarboxylic acid to give 50% inhibition of ternary complex formation. The stimulatory activity of both factors is abolished by pretreatment of the proteins with N-ethylmaleimide. Artemia eIF-2 rapidly bonds [3H]GDP or [3H]GTP and at 15 degrees C the initiation factor rapidly equilibrates bound nucleotides with free GDP or GTP. Both Co-eIF-2(A) and Co-eIF-2(B) have no effect on the exchange or the amount of nucleotide bound. The small subunit (Mr 43 000) of Artemia eIF-2 is phosphorylated in the presence of the rabbit reticulocyte heme-repressible kinase. Tryptic digestion of [32P]phosphorylated eIF-2 produces a single major phosphopeptide and several minor ones. Acid hydrolysis of these phosphopeptides, as well as of [32P]phosphorylated eIF-2, demonstrates that the radioactivity is predominantly associated with phosphoserine. Phosphorylated Artemia eIF-2 is active in ternary complex formation, in AUG-dependent binding of [35S]Met-tRNAf to 40-S ribosomal subunits and in cell-free protein synthesis. Both Co-eIF-2(A) and Co-eIF-2(B) stimulate ternary complex formation with phosphorylated eIF-2. A kinase that phosphorylates the small subunit of eIF-2 is present in the post-ribosomal supernatant as well as in the ribosomal wash of developing Artemia embryos. PMID:6912815

  12. Green exciplex emission from a bilayer light-emitting diode containing a rare earth ternary complex

    NASA Astrophysics Data System (ADS)

    Gao, De-Qing; Huang, Yan-Yi; Huang, Chun-Hui; Li, Fu-You; Huang, Ling

    2001-12-01

    A bilayer organic light-emitting diode using a blue-fluorescent yttrium complex, tris(1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone)-(2,2 '-dipyridyl) yttrium [Y(PMIP) 3(Bipy)] (YPB) as an emitting material and poly( N-vinylcarbazole) (PVK) as a hole-transporting material emitted bright green light instead of blue light. It was attributed to the exciplex formation at the solid interface between the PVK and YPB layers, which was demonstrated by the measurement of the absorption, photoluminescence (PL) and photoluminescence excitation (PLE) spectra of the mixture of PVK and YPB (molar ratio 1:1). The device exhibited a maximum luminance of 177 cd/m 2 and a peak power efficiency of 0.02 lm/W.

  13. Evidence of Ternary Complex Formation in Trypanosoma cruzi trans-Sialidase Catalysis*

    PubMed Central

    Oliveira, Isadora A.; Gonçalves, Arlan S.; Neves, Jorge L.; von Itzstein, Mark; Todeschini, Adriane R.

    2014-01-01

    Trypanosoma cruzi trans-sialidase (TcTS) is a key target protein for Chagas disease chemotherapy. In this study, we investigated the implications of active site flexibility on the biochemical mechanism of TcTS. Molecular dynamics studies revealed remarkable plasticity in the TcTS catalytic site, demonstrating, for the first time, how donor substrate engagement with the enzyme induces an acceptor binding site in the catalytic pocket that was not previously captured in crystal structures. Furthermore, NMR data showed cooperative binding between donor and acceptor substrates, supporting theoretical results. In summary, our data put forward a coherent dynamic framework to understand how a glycosidase evolved its highly efficient trans-glycosidase activity. PMID:24194520

  14. Unpinning the Open-Circuit Voltage in Organic Solar Cells through Tuning Ternary Blend Active Layer Morphology

    NASA Astrophysics Data System (ADS)

    Khlyabich, Petr; Thompson, Barry; Loo, Yueh-Lin

    2015-03-01

    The use of ternary, as opposed to binary, blends having complementary absorption in active layers of organic bulk heterojunction solar cells is a simple approach to increase overall light absorption. While the open-circuit voltage (Voc) of such solar cells have generally been shown to be pinned by the smallest energy level difference between the donor and acceptor constituents, there have been materials systems, that when incorporated into active layers of solar cells, exhibit composition dependent and tunable Voc. Herein, we demonstrate that this Voc tunability in ternary blend solar cells is correlated with the morphology of the active layer. Chemical compatibility between the constituents in the blend, as probed by grazing-incidence X-ray diffraction (GIXD) measurements, affords Voc tuning. The constituents need not ``co-crystallize'' limited miscibility between the constituents in the active layers of solar cells affords Voc tunability. Poor physical interactions between the constituent domains within the active layers, on the other hand, result in devices that exhibit an invariant Voc that is pinned by the smallest energy level difference between the donor(s) and the acceptor(s). Our morphological studies thus support the proposed alloying model that was put forth originally.

  15. Effect of halogen substitutions on dUMP to stability of thymidylate synthase/dUMP/mTHF ternary complex using molecular dynamics simulation.

    PubMed

    Kaiyawet, Nopporn; Rungrotmongkol, Thanyada; Hannongbua, Supot

    2013-06-24

    The stability of the thymidylate synthase (TS)/2-deoxyuridine-5-monophosphate (dUMP)/5,10-methylene-5,6,7,8-tetrahydrofolate (mTHF) ternary complex formation and Michael addition are considered as important steps that are involved in the inhibition mechanism of the anticancer prodrug 5-fluorouracil (5-FU). Here, the effect of three different halogen substitutions on the C-5 position of the dUMP (XdUMPs = FdUMP, CldUMP, and BrdUMP), the normal substrate, on the stability of the TS/dUMP and TS/dUMP/mTHF binary and ternary complexes, respectively, was investigated via molecular dynamics simulation. The simulated results revealed that the stability of all the systems was substantially increased by mTHF binding to the catalytic pocket. In the ternary complex, a much greater stabilization of the dUMP and XdUMPs through electrostatic interactions, including charge-charge and hydrogen bond interactions, was found compared to mTHF. An additional unique hydrogen bond between the substituted fluorine of FdUMP and the hydroxyl group of the TS Y94 residue was observed in both the binary and ternary complexes. The distance between the S(-) atom of the TS C146 residue and the C6 atom of dUMP, at <4 Å in all systems, suggested that a Michael addition with the formation of a S-C6 covalent bond potentially occurred, although the hydrogen atom on C6 of dUMP is substituted by a halogen atom. The MM/PBSA binding free energy revealed the significant role of the bridging waters around the ligands in the increased binding affinity (∼10 kcal/mol) of dUMP/XdUMP, either alone or together with mTHF, toward TS. The order of the averaged binding affinity in the ternary systems was found to be CldUMP ≈ FdUMP > dUMP > BrdUMP, suggesting that CldUMP could be a potent candidate TS inhibitor, the same as FdUMP (the metabolite form of 5-FU). PMID:23705822

  16. Effect of citrate on the local Fe coordination in ferrihydrite, arsenate binding, and ternary arsenate complex formation

    NASA Astrophysics Data System (ADS)

    Mikutta, Christian; Frommer, Jakob; Voegelin, Andreas; Kaegi, Ralf; Kretzschmar, Ruben

    2010-10-01

    (III)-citrate species were found to bind As(V) via surface complexes indistinguishable by EXAFS from those of As(V) adsorbed to or coprecipitated with Fh. Our study implies that low molecular weight polyhydroxycarboxylates may enhance the mobility of As(V) in aqueous systems of high ionic strength (e.g., neutralizing acid mine drainage) by colloidal stabilization of suspended Fh particles and the formation of ternary As(V) complexes.

  17. The bacterial antitoxin HipB establishes a ternary complex with operator DNA and phosphorylated toxin HipA to regulate bacterial persistence

    PubMed Central

    Wen, Yurong; Behiels, Ester; Felix, Jan; Elegheert, Jonathan; Vergauwen, Bjorn; Devreese, Bart; Savvides, Savvas N.

    2014-01-01

    Nearly all bacteria exhibit a type of phenotypic growth described as persistence that is thought to underlie antibiotic tolerance and recalcitrant chronic infections. The chromosomally encoded high-persistence (Hip) toxin–antitoxin proteins HipASO and HipBSO from Shewanella oneidensis, a proteobacterium with unusual respiratory capacities, constitute a type II toxin–antitoxin protein module. Here we show that phosphorylated HipASO can engage in an unexpected ternary complex with HipBSO and double-stranded operator DNA that is distinct from the prototypical counterpart complex from Escherichia coli. The structure of HipBSO in complex with operator DNA reveals a flexible C-terminus that is sequestered by HipASO in the ternary complex, indicative of its role in binding HipASO to abolish its function in persistence. The structure of HipASO in complex with a non-hydrolyzable ATP analogue shows that HipASO autophosphorylation is coupled to an unusual conformational change of its phosphorylation loop. However, HipASO is unable to phosphorylate the translation factor Elongation factor Tu, contrary to previous reports, but in agreement with more recent findings. Our studies suggest that the phosphorylation state of HipA is an important factor in persistence and that the structural and mechanistic diversity of HipAB modules as regulatory factors in bacterial persistence is broader than previously thought. PMID:25056321

  18. Synthesis and photophysical studies of tetrazolate-based Eu(III) photoluminescent ternary complexes containing N-heterocyclic phosphine oxides auxiliary co-ligands.

    PubMed

    Mal, Suraj; Pietraszkiewicz, Marek; Pietraszkiewicz, Oksana

    2016-08-01

    Two new ternary tetrazolate Eu(III) complexes with phosphine oxide co-ligands Eu(PTO)3 ·(P1/P2) [PTO = 5-(2-pyridyl-1-oxide)tetrazole, P1 = diphenylphosphorylamino-phenylphosphoryl-benzene, P2 = diphenylphosphorylpyridine)-bis-isobutyricphosphoryl] were synthesized and characterized using UV, fluorescence, IR and (1) H NMR spectroscopic techniques. The analytical data prove that the complexes are mononuclear in nature and the central Eu(III) ion is coordinated by three N and three O atoms of tetrazolate, and two O atoms of the corresponding bidentate phosphine oxide ligands. The ancillary ligand increased the photoluminescence efficiency of Eu(PTO)3 ·P1 (complex 3) by twofold compared with our previously reported Eu(PTO)3 complex (complex 1). Copyright © 2015 John Wiley & Sons, Ltd. PMID:26679054

  19. 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.

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

    SciTech Connect

    Bennett, Brad C.; Wan, Qun; Ahmad, Md Faiz; Langan, Paul; Dealwis, Chris G.

    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 the 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.

  1. Novel One-Tube-One-Step Real-Time Methodology for Rapid Transcriptomic Biomarker Detection: Signal Amplification by Ternary Initiation Complexes.

    PubMed

    Fujita, Hiroto; Kataoka, Yuka; Tobita, Seiji; Kuwahara, Masayasu; Sugimoto, Naoki

    2016-07-19

    We have developed a novel RNA detection method, termed signal amplification by ternary initiation complexes (SATIC), in which an analyte sample is simply mixed with the relevant reagents and allowed to stand for a short time under isothermal conditions (37 °C). The advantage of the technique is that there is no requirement for (i) heat annealing, (ii) thermal cycling during the reaction, (iii) a reverse transcription step, or (iv) enzymatic or mechanical fragmentation of the target RNA. SATIC involves the formation of a ternary initiation complex between the target RNA, a circular DNA template, and a DNA primer, followed by rolling circle amplification (RCA) to generate multiple copies of G-quadruplex (G4) on a long DNA strand like beads on a string. The G4s can be specifically fluorescence-stained with N(3)-hydroxyethyl thioflavin T (ThT-HE), which emits weakly with single- and double-stranded RNA/DNA but strongly with parallel G4s. An improved dual SATIC system, which involves the formation of two different ternary initiation complexes in the RCA process, exhibited a wide quantitative detection range of 1-5000 pM. Furthermore, this enabled visual observation-based RNA detection, which is more rapid and convenient than conventional isothermal methods, such as reverse transcription-loop-mediated isothermal amplification, signal mediated amplification of RNA technology, and RNA-primed rolling circle amplification. Thus, SATIC methodology may serve as an on-site and real-time measurement technique for transcriptomic biomarkers for various diseases. PMID:27347743

  2. X-ray structure of the ternary MTX•NADPH complex of the anthrax dihydrofolate reductase: a pharmacophore for dual-site inhibitor design

    PubMed Central

    Bennett, Brad C.; Wan, Qun; Ahmad, Md Faiz; Dealwis, Chris G.

    2009-01-01

    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 the 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° 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 2.3Å 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 μM concentrations. The apparent Kd 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 μM. PMID:19374017

  3. Comparative studies between 4-allyl-, 4-phenyl- and 4-ethyl-1-(2-hydroxybenzoyl) thiosemicarbazides and the synthesis, characterization and DFT calculations of binary and ternary complexes derived from 4-ethyl (L(1)) and 2,2'-dipyridyl.

    PubMed

    Azhari, Shaker J; Mlahi, Mosaad R; Mostafa, Mohsen M

    2015-11-01

    The metal complexes of 4-ethyl-1-(2-hydroxybenzoyl) thiosemicarbazide (L(1)) with MCl2 (M=Co(2+), Cu(2+) and Zn(2+)) and Zn(Ac)2 in EtOH were synthesized and characterized using spectral (IR, (1)H-NMR, mass, UV-Visible), magnetic moment and thermal measurements. Binary and ternary complexes with the general formulae, [Cu(L(1)-H)2]·EtOH, [Co(L(1)-H)2], [Zn3(L(1)-H)(L(1))(Ac)5], [Cu2(L(2))2(L(1)-2H)2(H2O)2]·4H2O, [Co(L(2))(L(1)-2H)]·3H2O and [Zn2(L(2))(OH)(L(1)-3H)(H2O)]·1/2EtOH where L(2) is 2,2'-dipyridyl, have been suggested and characterized. The bond lengths, bond angles, chemical reactivates, energy components, binding energies and dipole moments for the isolated complexes were evaluated by DFT method from DMOL(3). Also, the MEP for L(1) is illustrated. The existence of the OH group in the Zn(2+) ternary complexes is confirmed by IR, mass and (1)H-NMR spectra. Biological activity for the L(1) and some its complexes was tested against DNA. Comparative studies between the ligation behavior and reactivity of our previous work derived from 4-phenyl- and 4-allyl-1-(2-hydroxybenzoyl) thiosemicarbazides have been investigated. PMID:26123512

  4. Role of alpha chain-IL-2 complex in the formation of the ternary complex of IL-2 and high-affinity IL-2 receptor.

    PubMed

    Kamio, M; Uchiyama, T; Arima, N; Itoh, K; Ishikawa, T; Hori, T; Uchino, H

    1990-01-01

    Using anti-Tac (anti-alpha chain) and 2R-B (anti-beta chain) antibodies, we studied the roles of IL-2 receptor subunits (alpha and beta chains) in the formation of IL-2 and high-affinity IL-2 receptor complex, which is the initial event of IL-2 induced T cell growth. High-affinity IL-2 binding which was undetectable in the presence of 2R-B antibody at 4 degrees C became fully detectable when examined at 37 degrees C, which explained the lack of inhibition by 2R-B antibody of IL-2-induced proliferation of the cells expressing high-affinity IL-2 receptor. We further studied the mechanism of the 'reappearance' of high-affinity IL-2 binding in the presence of 2R-B antibody. The addition of IL-2 to the cells preincubated with radiolabeled or fluorescence-labeled 2R-B antibody resulted in a marked decrease in the antibody bound to the cells expressing high-affinity IL-2 receptor at 37 degrees C. This decrease was blocked by the presence of anti-Tac antibody, which inhibited IL-2 binding to alpha chain, but not by 7G7/B6 antibody, which recognized a non-IL-2 binding site of its chain. Furthermore, the decrease in cell-bound 2R-B antibody was not due to the internalization of beta chain-2R-B antibody complex, because the amount of cell-bound Mik-beta3 antibody recognizing a non-IL-2 binding epitope of beta chain remained unchanged, nor to the inhibition by simple competitive binding of IL-2 molecules to beta chain as judged from comparative studies of competitive binding inhibition. Taking these data together, the reappearance of high-affinity IL-2 binding was considered to be caused by the replacement of 2R-B antibody at the IL-2 binding site of beta chain by alpha chain-mediated IL-2, and it was strongly suggested that alpha chain-IL-2 complex has a key role in the formation of the ternary complex of IL-2 and high-affinity IL-2 receptor. alpha chain may function as a dimension converter of IL-2 to effectively deliver IL-2 molecules to a relatively small number of beta

  5. Binary and ternary doping of nitrogen, boron, and phosphorus into carbon for enhancing electrochemical oxygen reduction activity.

    PubMed

    Choi, Chang Hyuck; Park, Sung Hyeon; Woo, Seong Ihl

    2012-08-28

    N-doped carbon, a promising alternative to Pt catalyst for oxygen reduction reactions (ORRs) in acidic media, is modified in order to increase its catalytic activity through the additional doping of B and P at the carbon growth step. This additional doping alters the electrical, physical, and morphological properties of the carbon. The B-doping reinforces the sp(2)-structure of graphite and increases the portion of pyridinic-N sites in the carbon lattice, whereas P-doping enhances the charge delocalization of the carbon atoms and produces carbon structures with many edge sites. These electrical and physical alternations of the N-doped carbon are more favorable for the reduction of the oxygen on the carbon surface. Compared with N-doped carbon, B,N-doped or P,N-doped carbon shows 1.2 or 2.1 times higher ORR activity at 0.6 V (vs RHE) in acidic media. The most active catalyst in the reaction is the ternary-doped carbon (B,P,N-doped carbon), which records -6.0 mA/mg of mass activity at 0.6 V (vs RHE), and it is 2.3 times higher than that of the N-doped carbon. These results imply that the binary or ternary doping of B and P with N into carbon induces remarkable performance enhancements, and the charge delocalization of the carbon atoms or number of edge sites of the carbon is a significant factor in deciding the oxygen reduction activity in carbon-based catalysts. PMID:22769428

  6. Newly-designed complex ternary Pt/PdCu nanoboxes anchored on three-dimensional graphene framework for highly efficient ethanol oxidation.

    PubMed

    Hu, Chuangang; Cheng, Huhu; Zhao, Yang; Hu, Yue; Liu, Yong; Dai, Liming; Qu, Liangti

    2012-10-23

    Newly-designed ternary Pt/PdCu nanoboxes on three-dimensional graphene framework (Pt/PdCu/3DGF) have been fabricated via a dual solvothermal strategy. This structurally well-defined Pt/PdCu/3DGF system possesses an approximately 4-fold improvement in catalytic activity for ethanol oxidation in alkaline media over the commercial 20% Pt/C catalyst as normalized by the total mass of active metals, showing the great potential for direct fuel cell applications. PMID:22886893

  7. 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

    2016-05-01

    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. PMID:27067461

  8. 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

  9. One-pot solvothermal preparation and enhanced photocatalytic activity of metallic silver and graphene co-doped BiVO4 ternary systems

    NASA Astrophysics Data System (ADS)

    Xu, Lei; Wei, Yongge; Guo, Wan; Guo, Yihang; Guo, Yingna

    2015-03-01

    A series of metallic silver and graphene (GR) co-doped monoclinic BiVO4 ternary systems (Ag/GR/BiVO4) are demonstrated by a single-step solvothermal method. The phase and chemical structure, morphology, textural and optical absorption properties of the Ag/GR/BiVO4 ternary systems are well characterized, and then their simulated sunlight and visible-light photocatalytic activity were evaluated by the degradation of a typical dye pollutant, rhodamine B (RhB). For comparison, binary systems of Ag/BiVO4 and GR/BiVO4 as well as solitary BiVO4 are also tested under the same conditions. Meanwhile, the separation and transportation of the photogenerated carriers in the simulated sunlight-irradiating Ag/GR/BiVO4 ternary systems are studied by photoelectrochemistry experiments, and the active species generated during the process of photodegradation are investigated by free radical and hole scavenging experiments. On the basis of the above results, mechanism of photocatalytic degradation of RhB over the Ag/GR/BiVO4 ternary system is revealed. Finally, the reusability of the catalyst was evaluated by five consecutive catalytic runs.

  10. NMR-based modeling and binding studies of a ternary complex between chicken liver bile acid binding protein and bile acids.

    PubMed

    Tomaselli, Simona; Ragona, Laura; Zetta, Lucia; Assfalg, Michael; Ferranti, Pasquale; Longhi, Renato; Bonvin, Alexandre M J J; Molinari, Henriette

    2007-10-01

    Chicken liver bile acid binding protein (cL-BABP) is involved in bile acid transport in the liver cytosol. A detailed study of the mechanism of binding and selectivity of bile acids binding proteins towards the physiological pool of bile salts is a key issue for the complete understanding of the role of these proteins and their involvement in cholesterol homeostasis. In the present study, we modeled the ternary complex of cL-BABP with two molecules of bile salts using the data driven docking program HADDOCK on the basis of NMR and mass spectrometry data. Docking resulted in good 3D models, satisfying the majority of experimental restraints. The docking procedure represents a necessary step to help in the structure determination and in functional analysis of such systems, in view of the high complexity of the 3D structure determination of a ternary complex with two identical ligands. HADDOCK models show that residues involved in binding are mainly located in the C-terminal end of the protein, with two loops, CD and EF, playing a major role in ligand binding. A spine, comprising polarresidues pointing toward the protein interior and involved in motion communication, has a prominent role in ligand interaction. The modeling approach has been complemented with NMR interaction and competition studies of cL-BABP with chenodeoxycholic and cholic acids. A higher affinity for chenodeoxycholic acid was observed and a Kd upper limit estimate was obtained. The binding is highly cooperative and no site selectivity was detected for the different bile salts, thus indicating that site selectivity and cooperativity are not correlated. Differences in physiological pathways and bile salt pools in different species is discussed in light of the binding results thus enlarging the body of knowledge of BABPs biological functions. PMID:17607743

  11. Crystallization and preliminary crystallographic data for a ternary complex between tissue factor, factor VIIa and a BPTI-derived inhibitor

    NASA Astrophysics Data System (ADS)

    Stura, Enrico A.; Ruf, Wolfram; Wilson, Ian A.

    1996-10-01

    The binding of tissue factor (TF) with the serine protease coagulation factor VIIa (VIIa) is the initial trigger for activation of the coagulation protease cascades. In complex with TF, VIIa has profoundly enhanced function in the limited proteolytic activation of the natural substrate factors X and IX. Here we report the screening and identification of crystallization conditions to produce diffraction quality crystals of the complex between TF · VIIa and a potent inhibitor (5L 15) derived from mutagenesis of the bovine pancreatic trypsin inhibitor (BPTI) sequence. The complex crystals were obtained from the soluble extracellular domain of tissue factor, expressed in Escherichia coli as a fusion protein, VIIa expressed in mammalian cells and recombinant 5L15. Because only 1.5 mg of complex were available for this work, a reverse screening based strategy was used in the search and optimization of the crystallization conditions. Two different crystal forms were obtained from polyethylene glycol 4000 and monomethyl polyethylene glycol 2000 with cacodylate buffer at pH 6.5 in the presence of sodium and calcium ions. The addition of magnesium and zinc have profound effects on the crystallization. Both crystal forms are trigonal with cell parameters a = b = 129.3 Å, c = 110.8 Å and a = b = 67.2 Å, c = 314.8 Å diffracting to 7 and 3.2 Å resolution, respectively, each with one molecule in the asymmetric unit. Complete data sets have been collected from each of these forms to the resolution to which the crystals diffract. A structural understanding of the interaction of VIIa with its cofactor TF to form a binary enzyme, and its inhibition by 5L15 will provide a basis for the development of antithrombotic strategies.

  12. 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.

  13. Functionalized active-nucleus complex sensor

    DOEpatents

    Pines, Alexander; Wemmer, David E.; Spence, Megan; Rubin, Seth

    2003-11-25

    A functionalized active-nucleus complex sensor that selectively associates with one or more target species, and a method for assaying and screening for one or a plurality of target species utilizing one or a plurality of functionalized active-nucleus complexes with at least two of the functionalized active-nucleus complexes having an attraction affinity to different corresponding target species. The functionalized active-nucleus complex has an active-nucleus and a targeting carrier. The method involves functionalizing an active-nucleus, for each functionalized active-nucleus complex, by incorporating the active-nucleus into a macromolucular or molecular complex that is capable of binding one of the target species and then bringing the macromolecular or molecular complexes into contact with the target species and detecting the occurrence of or change in a nuclear magnetic resonance signal from each of the active-nuclei in each of the functionalized active-nucleus complexes.

  14. 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. PMID:22283512

  15. Evaluation of the activity and molecular form of bi in cu smelting slags: Part I. ternary silicate slags

    NASA Astrophysics Data System (ADS)

    Marschman, S. C.; Lynch, D. C.

    1988-08-01

    The thermodynamic behavior of bismuth in the chemical systems associated with copper processing is not well understood. This study was designed to further the understanding of the physical chemistry of bismuth in slags that have similar compositions to those found in copper extractive metallurgical processing. The silicate system investigated was the FeO-Fe2O3-SiO2 ternary system in which bismuth was dissolved using an isopiestic experimental technique. Bismuth vapor pressures of 1 • 10-5 atm and 7.5 • 10-4 atm were used, and the silicates were equilibrated with this vapor at temperatures of 1458 K and 1523 K. In these experiments, the slag composition was varied such that P O 2 ranged from 10-12 to 10-8 atm. Bismuth was found to enter the silicate slag in both neutral and oxidic molecular forms. The oxidic form identified was that of BiO. The data suggest that the activity coefficient of neutral bismuth, γBi, is dependent on the solubility of that species in slag, even at the low concentrations observed in this study. It has been hypothesized, based on the large diameter of neutral Bi, that only a limited number of sites are available to accommodate neutral Bi, and that as the limit is approached γBi increases significantly. That hypothesis is shown to be consistent with the experimental results obtained in the present work as well as the results obtained by other investigators.

  16. Spectrofluorimetric Determination of Famotidine in Pharmaceutical Preparations and Biological Fluids through Ternary Complex Formation with Some Lanthanide Ions: Application to Stability Studies

    PubMed Central

    Walash, M. I.; El-Brashy, A.; El-Enany, N.; Wahba, M. E. K.

    2009-01-01

    A simple, sensitive and specific method was developed for the determination of famotidine (FMT) in pharmaceutical preparations and biological fluids. The proposed method is based on ternary complex formation of famotidine (FMT) with EDTA and terbium chloride TbCl3 in acetate buffer of pH 4. Alternatively, the complex is formed via the reaction with hexamine and either lanthanum chloride LaCl3, or cerous chloride CeCl3 in borate buffer of pH6.2 and 7.2 respectively. In all cases, the relative fluorescence intensity of the formed complexes was measured at 580 nm after excitation at 290 nm. The fluorescence intensity - concentration plots were rectilinear over the concentration range of 10-100, 5-70, and 5-60 ng/ml, with minimum quantification limits (LOQ) of 2.4, 2.2, and 5.2 ng/ml, and minimum limits of detection (LOD) of 0.79, 0.74, and 1.7 ng/ml upon using TbCl3, LaCl3, and CeCl3 respectively. The proposed method was applied successfully for the analysis of famotidine in dosage forms and in human plasma. The kinetics of both alkaline and oxidative induced degradation of the drug was studied using the proposed method. The apparent first order rate constant and half life time were calculated. A proposal of the reaction pathways is presented. PMID:23675130

  17. Influence of the active layer nanomorphology on device performance for ternary PbS(x)Se(1-x) quantum dots based solution-processed infrared photodetector.

    PubMed

    Song, Taojian; Cheng, Haijuan; Fu, Chunjie; He, Bo; Li, Weile; Xu, Junfeng; Tang, Yi; Yang, Shengyi; Zou, Bingsuo

    2016-04-22

    In this paper, the influence of the active layer nanomorphology on device performance for ternary PbS(x)Se(1-x) quantum dot-based solution-processed infrared photodetector is presented. Firstly, ternary PbS(x)Se(1-x) quantum dots (QDs) in various chemical composition were synthesized and the bandgap of the ternary PbS(x)Se(1-x) QDs can be controlled by the component ratio of S/(S + Se), and then field-effect transistor (FET) based photodetectors Au/PbS0.4Se0.6:P3HT/PMMA/Al, in which ternary PbS0.4Se0.6 QDs doped with poly(3-hexylthiophene) (P3HT) act as the active layer and poly(methyl methacrylate) (PMMA) as the dielectric layer, were presented. By changing the weight ratio of P3HT to PbS0.4Se0.6 QDs (K = M(P3HT):M(QDs)) in dichlorobenzene solution, we found that the device with K = 2:1 shows optimal electrical property in dark; however, the device with K = 1:2 demonstrated optimal performance under illumination, showing a maximum responsivity and specific detectivity of 55.98 mA W(-1) and 1.02 × 10(10) Jones, respectively, at low V(DS) = -10 V and V(G) = 3 V under 980 nm laser with an illumination intensity of 0.1 mW cm(-2). By measuring the atomic force microscopy phase images of PbS0.4Se0.6:P3HT films in different weight ratio K, our experimental data show that the active layer nanomorphology has a great influence on the device performance. Also, it provides an easy way to fabricate high performance solution-processed infrared photodetector. PMID:26963474

  18. Influence of the active layer nanomorphology on device performance for ternary PbS x Se1-x quantum dots based solution-processed infrared photodetector

    NASA Astrophysics Data System (ADS)

    Song, Taojian; Cheng, Haijuan; Fu, Chunjie; He, Bo; Li, Weile; Xu, Junfeng; Tang, Yi; Yang, Shengyi; Zou, Bingsuo

    2016-04-01

    In this paper, the influence of the active layer nanomorphology on device performance for ternary PbS x Se1-x quantum dot-based solution-processed infrared photodetector is presented. Firstly, ternary PbS x Se1-x quantum dots (QDs) in various chemical composition were synthesized and the bandgap of the ternary PbS x Se1-x QDs can be controlled by the component ratio of S/(S + Se), and then field-effect transistor (FET) based photodetectors Au/PbS0.4Se0.6:P3HT/PMMA/Al, in which ternary PbS0.4Se0.6 QDs doped with poly(3-hexylthiophene) (P3HT) act as the active layer and poly(methyl methacrylate) (PMMA) as the dielectric layer, were presented. By changing the weight ratio of P3HT to PbS0.4Se0.6 QDs (K = MP3HT:MQDs) in dichlorobenzene solution, we found that the device with K = 2:1 shows optimal electrical property in dark; however, the device with K = 1:2 demonstrated optimal performance under illumination, showing a maximum responsivity and specific detectivity of 55.98 mA W-1 and 1.02 × 1010 Jones, respectively, at low V DS = -10 V and V G = 3 V under 980 nm laser with an illumination intensity of 0.1 mW cm-2. By measuring the atomic force microscopy phase images of PbS0.4Se0.6:P3HT films in different weight ratio K, our experimental data show that the active layer nanomorphology has a great influence on the device performance. Also, it provides an easy way to fabricate high performance solution-processed infrared photodetector.

  19. Structure of the ternary complex formed by a chemotaxis receptor signaling domain, the CheA histidine kinase and the coupling protein CheW as determined by pulsed dipolar ESR spectroscopy†

    PubMed Central

    Bhatnagar, Jaya; Borbat, Peter P.; Pollard, Abiola M.; Bilwes, Alexandrine M.; Freed, Jack H.; Crane, Brian R.

    2010-01-01

    The signaling apparatus that controls bacterial chemotaxis is composed of a core complex containing chemoreceptors, the histidine auto-kinase CheA, and the coupling protein CheW. Site-specific spin labeling and pulsed-dipolar ESR spectroscopy (PDS) have been applied to investigate the structure of a soluble ternary complex formed by T. maritima CheA (TmCheA), CheW, and receptor signaling domains. Thirty-five symmetric spin-labels sites (SLSs) were engineered into the five domains of the CheA dimer and CheW to provide distance restraints within the CheA:CheW complex in the absence and presence of a soluble receptor that inhibits kinase activity (Tm14). Additional PDS restraints between spin-labeled CheA, CheW and an engineered single-chain receptor labeled at six different sites allows docking of the receptor structure relative to the CheA:CheW complex. Disulfide cross-linking between selectively incorporated Cys residues finds two pairs of positions that provide further constraints within the ternary complex: one involving Tm14 and CheW, and another involving Tm14 and CheA. The derived structure of the ternary complex indicates a primary site of interaction between CheW and Tm14 that agrees well with previous biochemical and genetic data on transmembrane chemoreceptors. The PDS distance distributions are most consistent with only one CheW directly engaging one dimeric Tm14. The CheA dimerization domain (P3) aligns roughly antiparallel to the receptor conserved signaling tip, but does not interact strongly with it. The angle of the receptor axis with respect to P3 and the CheW-binding P5 domains is bound by two limits differing by ~20°. In one limit, Tm14 aligns roughly along P3 and may interact to some extent with the hinge region near the P3 hairpin loop. In the other limit, Tm14 tilts to interact with the P5 domain of the opposite subunit in an interface that mimics that observed with the P5 homolog CheW. The time-domain ESR data can be simulated from the model

  20. A ternary composite based on graphene, hemin, and gold nanorods with high catalytic activity for the detection of cell-surface glycan expression.

    PubMed

    Liu, Jing; Xin, Xiaoyan; Zhou, Hong; Zhang, Shusheng

    2015-01-26

    A novel graphene-family ternary composite with high catalytic activity has been developed by using simple synthetic methods. The graphene-based ternary composite has abundant positively charged Au NRs, which greatly improved the catalytic properties of the graphene-family of peroxidase mimetics, because of the high electron-transfer rate of graphene and the synergistic interaction of three components. Sensitive detection of glycan expression on K562 cell surface can be achieved with a low detection limit of 10 cells. This finding constitutes a novel graphene-family hybrid nanomaterials-based peroxidase mimetic that is expected to be applied widely in the construction of simple, sensitive, and selective biosensors for nucleic acids and proteins both inside and outside of cells through catalytic reaction of H2 O2 . PMID:25418152

  1. Photoeletrocatalytic activity of an n-ZnO/p-Cu2O/n-TNA ternary heterojunction electrode for tetracycline degradation.

    PubMed

    Li, Jinhua; Lv, Shubin; Liu, Yanbiao; Bai, Jing; Zhou, Baoxue; Hu, Xiaofang

    2013-11-15

    In this study, a novel ternary heterojunction n-ZnO/p-Cu2O/n-TiO2 nanotube arrays (n-ZnO/p-Cu2O/n-TNA) nanophotocatalyst with a sandwich-like nanostructure was constructed and applied for the photoelectrocatalytic (PEC) degradation of typical PPCPs, tetracycline (TC). The ternary heterojunction n-ZnO/p-Cu2O/n-TNA was obtained by depositing Cu2O on the surface of TNA via sonoelectrochemical deposition (SED) and subsequently building a layer of ZnO onto the p-Cu2O/n-TNA surface through hydrothermal synthesis. After being deposited by the Cu2O, the absorption-band edge of the p-Cu2O/n-TNA was obviously red-shifted to the visible region (to 505 nm), and the band gap was reduced from its original 3.20 eV to 2.46 eV. The band gap absorption edge of the ternary n-ZnO/p-Cu2O/n-TNA is similar to that of p-Cu2O/n-TN and extends the visible spectrum absorption to 510 nm, corresponding to an Eg value of about 2.43 eV. Under illumination of visible light, the photocurrent density of the ternary heterojunction n-ZnO/p-Cu2O/n-TNA electrode at 0.5 V (vs. Ag/AgCl) was more than 106 times as high as that of the pure TNAs electrode, 3.6 times as high as that of the binary heterojunction p-Cu2O/n-TNA electrode. The degradation of TC indicated that the ternary heterojunction n-ZnO/p-Cu2O/n-TNA electrode maintained a very high photoelectrocatalytic activity and excellent stability and reliability. Such kind of ternary heterojunction electrode material has a broad application prospect not only in pollution control but also in many other fields. PMID:24076571

  2. Structure of the Dual-Mode Wnt Regulator Kremen1 and Insight into Ternary Complex Formation with LRP6 and Dickkopf.

    PubMed

    Zebisch, Matthias; Jackson, Verity A; Zhao, Yuguang; Jones, E Yvonne

    2016-09-01

    Kremen 1 and 2 have been identified as co-receptors for Dickkopf (Dkk) proteins, hallmark secreted antagonists of canonical Wnt signaling. We present here three crystal structures of the ectodomain of human Kremen1 (KRM1ECD) at resolutions between 1.9 and 3.2 Å. KRM1ECD emerges as a rigid molecule with tight interactions stabilizing a triangular arrangement of its Kringle, WSC, and CUB structural domains. The structures reveal an unpredicted homology of the WSC domain to hepatocyte growth factor. We further report the general architecture of the ternary complex formed by the Wnt co-receptor Lrp5/6, Dkk, and Krm, determined from a low-resolution complex crystal structure between β-propeller/EGF repeats (PE) 3 and 4 of the Wnt co-receptor LRP6 (LRP6PE3PE4), the cysteine-rich domain 2 (CRD2) of DKK1, and KRM1ECD. DKK1CRD2 is sandwiched between LRP6PE3 and KRM1Kringle-WSC. Modeling studies supported by surface plasmon resonance suggest a direct interaction site between Krm1CUB and Lrp6PE2. PMID:27524201

  3. Structures and Stabilities of Ternary Copper(II) Complexes with 3,5-Diiodo-L-tyrosinate. Weak Interactions Involving Iodo Groups.

    PubMed

    Zhang, Feng; Odani, Akira; Masuda, Hideki; Yamauchi, Osamu

    1996-11-20

    Structures and stabilities of the ternary copper(II) complexes Cu(DA)(AA), where AA refers to 3,5-diiodo-L-tyrosinate (I(2)tyr) or L-tyrosinate (Tyr) and DA refers to 1,10-phenanthroline (phen), 2,2'-bipyridine (bpy), 2-(aminomethyl)pyridine (ampy), histamine (hista), or ethylenediamine (en), have been investigated by potentiometric, spectroscopic, and X-ray diffraction methods. The stability constants have been determined by potentiometric titrations at 25 degrees C and ionic strength I = 0.1 M (KNO(3)). The equilibrium constants K for a hypothetical equilibrium, Cu(DA)(Ala) + Cu(en)(AA) Cu(DA)(AA) + Cu(en)(Ala) where Ala refers to L-alanine, have been calculated from the determined overall stability constants of the ternary complexes for estimating the stability enhancement due to the stacking interaction between the aromatic rings in Cu(DA)(AA). Large positive log K values have been obtained for the Cu(DA)(I(2)tyrOH) and Cu(DA)(I(2)tyrO(-)) systems (DA = phen or bpy, OH and O(-) refer to the protonated and deprotonated forms of the phenol moiety, respectively), indicating that the complexes are stabilized by effective stacking. Differences between the log K values for Cu(DA)(I(2)tyr) and Cu(DA)(Tyr) systems indicate that the iodine substituents greatly contribute to the stability enhancement. A distinct circular dichroism (CD) magnitude anomaly was also observed for the systems with large log K value, supporting the existence of the stacking interaction in Cu(DA)(AA). Two complexes, [Cu(bpy)(I(2)tyrO(-))(H(2)O)].2H(2)O (1) and [Cu(bpy)(I(2)tyrOH)(NO(3))].CH(3)OH (2), have been isolated as crystals and analyzed by the X-ray diffraction method. Both 1 and 2 crystallized in the orthorhombic space group P2(1)2(1)2(1) with four molecules in a unit cell of dimensions a = 9.2339(4), b = 16.9230(8), and c = 14.8584(5) Å for complex 1, and a = 11.2240(8), b = 11.715(1), and c = 17.966(2) Å for complex 2. The central Cu(II) ion for both complexes has a similar distorted

  4. Single-step solvothermal synthesis of mesoporous Ag-TiO2-reduced graphene oxide ternary composites with enhanced photocatalytic activity.

    PubMed

    Sher Shah, Md Selim Arif; Zhang, Kan; Park, A Reum; Kim, Kwang Su; Park, Nam-Gyu; Park, Jong Hyeok; Yoo, Pil J

    2013-06-01

    With growing interest in the photocatalytic performance of TiO2-graphene composite systems, the ternary phase of TiO2, graphene, and Ag is expected to exhibit improved photocatalytic characteristics because of the improved recombination rate of photogenerated charge carriers and potential contribution of the generation of localized surface plasmon resonance at Ag sites on a surface of the TiO2-graphene binary matrix. In this work, Ag-TiO2-reduced graphene oxide ternary nanocomposites were successfully synthesized by a simple solvothermal process. In a single-step synthetic procedure, the reduction of AgNO3 and graphene oxide and the hydrolysis of titanium tetraisopropoxide were spontaneously performed in a mixed solvent system of ethylene glycol, N,N-dimethylformamide and a stoichiometric amount of water without resorting to the use of typical reducing agents. The nanocomposites were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, along with different microscopic and spectroscopic techniques, enabling us to confirm the successful reduction of AgNO3 and graphite oxide to metallic Ag and reduced graphene oxide, respectively. Due to the highly facilitated electron transport of well distributed Ag nanoparticles, the synthesized ternary nanocomposite showed enhanced photocatalytic activity for degradation of rhodamine B dye under visible light irradiation. PMID:23640656

  5. Estrogenic activity of ternary UV filter mixtures in fish (Pimephales promelas) - an analysis with nonlinear isobolograms.

    PubMed

    Kunz, Petra Y; Fent, Karl

    2009-01-01

    Numerous estrogenic compounds are present in aquatic environments, but currently it is not well understood how compounds that differ in maxima and slope of their individual dose-response curves contribute to the overall mixture effect. In order to better understand such interactions we investigated 3 commonly used UV filters, for their estrogenic mixture activity and analysed their joint effects by using the concentration addition (CA) concept. Thereby, we extended the method of isoboles for analysis of 3 compounds that differ in maxima and slopes of their dose-response curves. 3-Benzylidene camphor (3BC), benzophenone-1 (BP1) and benzophenone-2 (BP2) are estrogenic in fish and act as pure- or partial estrogen receptor alpha agonists. First we exposed juvenile fathead minnows for 14 days to six concentrations of each UV filter alone to determine vitellogenin (VTG) induction curves, calculate equi-effective mixture concentrations and predict mixture effects. For 3BC, BP1 and BP2 significant VTG-induction occurred at 420, 2668, and 4715 microg/L, respectively. BP2 displayed a full dose-response curve, whereas 3BC and BP1 showed submaximal activity of 70 and 78%, respectively. Second, we exposed fish to 6 equi-effective mixtures (EC-NOEC, EC1, EC5, EC10, EC20, EC30) of these UV filters. Significant VTG-induction occurred at EC5 and higher. Submaximal activity of 67% as compared to the control EE2 (100 ng/L) was reached. The curves for the observed and predicted mixture activity agreed for mixture levels (EC10 to EC30), however, at EC-NOEC, EC1 and EC5, lower activity was observed than predicted by CA. Detailed isobolographic analysis indicate additivity at EC10 to EC30, and antagonism at low levels (EC-NOEC to EC5). Our data show for the first time, that for compounds with differences in maxima and slope, considerably more mixture combinations are additive than previously thought. This should be taken into account for hazard and risk assessment of UV filters and

  6. Estrogenic activity of ternary UV filter mixtures in fish (Pimephales promelas) - An analysis with nonlinear isobolograms

    SciTech Connect

    Kunz, Petra Y.; Fent, Karl

    2009-01-01

    Numerous estrogenic compounds are present in aquatic environments, but currently it is not well understood how compounds that differ in maxima and slope of their individual dose-response curves contribute to the overall mixture effect. In order to better understand such interactions we investigated 3 commonly used UV filters, for their estrogenic mixture activity and analysed their joint effects by using the concentration addition (CA) concept. Thereby, we extended the method of isoboles for analysis of 3 compounds that differ in maxima and slopes of their dose-response curves. 3-Benzylidene camphor (3BC), benzophenone-1 (BP1) and benzophenone-2 (BP2) are estrogenic in fish and act as pure- or partial estrogen receptor {alpha} agonists. First we exposed juvenile fathead minnows for 14 days to six concentrations of each UV filter alone to determine vitellogenin (VTG) induction curves, calculate equi-effective mixture concentrations and predict mixture effects. For 3BC, BP1 and BP2 significant VTG-induction occurred at 420, 2668, and 4715 {mu}g/L, respectively. BP2 displayed a full dose-response curve, whereas 3BC and BP1 showed submaximal activity of 70 and 78%, respectively. Second, we exposed fish to 6 equi-effective mixtures (EC-NOEC, EC1, EC5, EC10, EC20, EC30) of these UV filters. Significant VTG-induction occurred at EC5 and higher. Submaximal activity of 67% as compared to the control EE2 (100 ng/L) was reached. The curves for the observed and predicted mixture activity agreed for mixture levels (EC10 to EC30), however, at EC-NOEC, EC1 and EC5, lower activity was observed than predicted by CA. Detailed isobolographic analysis indicate additivity at EC10 to EC30, and antagonism at low levels (EC-NOEC to EC5). Our data show for the first time, that for compounds with differences in maxima and slope, considerably more mixture combinations are additive than previously thought. This should be taken into account for hazard and risk assessment of UV filters and

  7. Crystal Structure of the Ternary Complex of a NaV C-Terminal Domain, a Fibroblast Growth Factor Homologous Factor, and Calmodulin

    SciTech Connect

    Wang, Chaojian; Chung, Ben C.; Yan, Haidun; Lee, Seok-Yong; Pitt, Geoffrey S.

    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}. 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.

  8. Mechanistic and structural studies of apoform, binary, and ternary complexes of the Arabidopsis alkenal double bond reductase At5g16970.

    PubMed

    Youn, Buhyun; Kim, Sung-Jin; Moinuddin, Syed G A; Lee, Choonseok; Bedgar, Diana L; Harper, Athena R; Davin, Laurence B; Lewis, Norman G; Kang, Chulhee

    2006-12-29

    In this study, we determined the crystal structures of the apoform, binary, and ternary complexes of the Arabidopsis alkenal double bond reductase encoded by At5g16970. This protein, one of 11 homologues in Arabidopsis thaliana, is most closely related to the Pinus taeda phenylpropenal double bond reductase, involved in, for example, heartwood formation. Both enzymes also have essential roles in plant defense, and can function by catalyzing the reduction of the 7-8-double bond of phenylpropanal substrates, such as p-coumaryl and coniferyl aldehydes in vitro. At5g16970 is also capable of reducing toxic substrates with the same alkenal functionality, such as 4-hydroxy-(2E)-nonenal. The overall fold of At5g16970 is similar to that of the zinc-independent medium chain dehydrogenase/reductase superfamily, the members of which have two domains and are dimeric in nature, i.e. in contrast to their original classification as being zinc-containing oxidoreductases. As provisionally anticipated from the kinetic data, the shape of the binding pocket can readily accommodate p-coumaryl aldehyde, coniferyl aldehyde, 4-hydroxy-(2E)-nonenal, and 2-alkenals. However, the enzyme kinetic data among these potential substrates differ, favoring p-coumaryl aldehyde. Tyr-260 is provisionally proposed to function as a general acid/base for hydride transfer. A catalytic mechanism for this reduction, and its applicability to related important detoxification mammalian proteins, is also proposed. PMID:17028190

  9. Sensitive Determination of Uranium in Natural Waters Using UV-Vis Spectrometry After Preconcentration by Ion-Imprinted Polymer-Ternary Complexes.

    PubMed

    Bicim, Tulin; Yaman, Mehmet

    2016-07-01

    The main purpose of this study was to achieve a substantial increase in the sensitivity of the uranium determination using UV-Vis spectrometry. To achieve this goal, ion-imprinted polymers were prepared for the uranyl (imprint) ion by the formation of a ternary (salicylaldoxime and 4-vinylpyridine) complex in 2-methoxy ethanol (porogen) following copolymerization with methacrylic acid. The synthesized polymers were characterized by FTIR analysis and thermogravimetric analysis. In the preconcentration step, the optimal pH was determined to be between values of 3.5 and 6.5. The adsorbed UO2(2+) was completely eluted by 10 mL of 3.0 mol L(-1) HClO4. The developed method was applied to uranium (VI) determination in natural water samples. By using the initial volume of 500 mL and final volume of 5 mL, a concentration of 1 μg L(-1) can be determined by applying the developed method in this study. PMID:27302914

  10. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    SciTech Connect

    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

    2015-12-17

    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 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. As a result, the active site architecture shows clear evidence of having arisen by convergent evolution.

  11. 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

  12. 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.

  13. Study of enhanced red emission from Sm(Sal) 3Phen ternary complexes in Poly Vinyl Alcohol film

    NASA Astrophysics Data System (ADS)

    Kaur, Gagandeep; Dwivedi, Y.; Rai, S. B.

    2010-09-01

    In the present work, dinuclear complexes of salicylic acid (Sal) and 1,10-phenanthroline (Phen) were synthesized with different concentrations of Samarium ion (Sm 3+) in Poly Vinyl Alcohol (PVA) polymer films and their structural and spectroscopic properties were investigated. Judd-Ofelt theory has been employed to estimate the several radiative parameters for SmCl 3 and Sm(Sal) 3Phen complex in PVA polymer film which are in fairly agreement between the experimental and the theoretical values supporting the J-O theory. Photoluminescence properties of the complex have been studied on 355 nm and 400 nm excitations in steady state as well as in time domain. On the basis of the UV-Vis absorption, FT-IR absorption, excitation, emission spectra and decay curves, spectroscopic properties of these films were studied and the photophysics involved was explained in terms of energy transfer and the RE encapsulation effect.

  14. Ternary Copper(II) Complexes in Solution[1,2] Formed With 8-Aza Derivatives of the Antiviral Nucleotide Analogue 9-[2-(Phosphonomethoxy)Ethyl]Adenine (PMEA)

    PubMed Central

    Gómez-Coca, Raquel B.; Kapinos, Larisa E.; Holý, Antonín; Vilaplana, Rosario A.; González-Vílchez, Francisco

    2000-01-01

    The stability constants of the mixed-ligand complexes formed between Cu(Arm)2+, where Arm= 2,2'-bipyridine (Bpy) or 1,10-phenanthroline (Phen), and the dianions of 9-[2-(phosphonomethoxy)ethyl]-8-azaadenine (9,8aPMEA) and 8-[2-(phosphonomethoxy)ethyl]-8-azaadenine (8,8aPMEA) (both also abbreviated as PA2-) were determined by potentiometric pH titrations in aqueous solution (25 °C; I = 0.1 M, NaNO3). All four ternary Cu(Arm)(PA) complexes are considerably more stable than corresponding Cu(Arm)(R-PO3) species, where R-PO32- represents a phosph(on)ate ligand with a group R that is unable to participate in any kind of interaction within the complexes. The increased stability is attributed to intramolecular stack formation in the Cu(Arm)(PA) complexes and also to the formation of 5-membered chelates involving the ether oxygen present in the -CH2-O-CH2-PO32- residue of the azaPMEAs. A quantitative analysis of the intramolecular equilibria involving three structurally different Cu(Arm)(PA) species is carried out. For example, about 5% of the Cu(Bpy)(8,8aPMEA) system exist with the metal ion solely coordinated to the phosphonate group, 14% as a 5-membered chelate involving the -CH2-O-CH2-PO32-residue, and 81% with an intramolecular stack between the 8-azapurine moiety and the aromatic rings of Bpy. The results for the other systems are similar though with Phen a formation degree of about 90% for the intramolecular stack is reached. The existence of the stacked species is also proven by spectrophotometric measurements. In addition, the Cu(Arm)(PA) complexes may be protonated, leading to Cu(Arm)(H;PA)+ species for which it is concluded that the proton is located at the phosphonate group and that the complexes are mainly formed by a stacking adduct between Cu(Arm)2+ and H(PA)-. Conclusions regarding the biological properties of these azaPMEAs are shortly indicated. PMID:18475963

  15. New type of blue ternary complex of arsenazo I with plutonium (IV) in the presence of hydrogen peroxide: preliminary investigations.

    PubMed

    Pérez-Bustamante, J A

    1974-12-01

    The preparation and spectrophotometric properties of a new type of complex compound of arsenazo I with Pu(IV) in the presence of H(2)O(2) are described. The new compound has a blue colour, derived from a wide absorption band with a maximum at 610 nm. and a corresponding molar absorptivity of 4 x 10(4) l. mole(-1).cm(-1). From 2 hr after its preparation this curious new compound undergoes for several days a steady decomposition accompanied by decolorization. The formation of similar peroxy Pu(IV) complexes has not so far been shown to take place with arsenazo III or with any other "arsenazo-type" reagent. PMID:18961599

  16. Balanced ternary addition using a gated silicon nanowire

    NASA Astrophysics Data System (ADS)

    Mol, J. A.; van der Heijden, J.; Verduijn, J.; Klein, M.; Remacle, F.; Rogge, S.

    2011-12-01

    Ternary logic has the lowest cost of complexity, here, we demonstrate a CMOS hardware implementation of a ternary adder using a silicon metal-on-insulator single electron transistor. Gate dependent rectifying behavior of a single electron transistor (SET) results in a robust three-valued output as a function of the potential of the single electron transistor island. Mapping logical, ternary inputs to the three gates controlling the potential of the single electron transistor island allows us to perform complex, inherently ternary operations, on a single transistor.

  17. Surface properties and photocatalytic activity of KTaO3, CdS, MoS2 semiconductors and their binary and ternary semiconductor composites.

    PubMed

    Bajorowicz, Beata; Cybula, Anna; Winiarski, Michał J; Klimczuk, Tomasz; Zaleska, Adriana

    2014-01-01

    Single semiconductors such as KTaO3, CdS MoS2 or their precursor solutions were combined to form novel binary and ternary semiconductor nanocomposites by the calcination or by the hydro/solvothermal mixed solutions methods, respectively. The aim of this work was to study the influence of preparation method as well as type and amount of the composite components on the surface properties and photocatalytic activity of the new semiconducting photoactive materials. We presented different binary and ternary combinations of the above semiconductors for phenol and toluene photocatalytic degradation and characterized by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface area and porosity. The results showed that loading MoS2 onto CdS as well as loading CdS onto KTaO3 significantly enhanced absorption properties as compared with single semiconductors. The highest photocatalytic activity in phenol degradation reaction under both UV-Vis and visible light irradiation and very good stability in toluene removal was observed for ternary hybrid obtained by calcination of KTaO3, CdS, MoS2 powders at the 10:5:1 molar ratio. Enhanced photoactivity could be related to the two-photon excitation in KTaO3-CdS-MoS2 composite under UV-Vis and/or to additional presence of CdMoO4 working as co-catalyst. PMID:25255249

  18. D-AKAP2:PKA RII:PDZK1 ternary complex structure: insights from the nucleation of a polyvalent scaffold.

    PubMed

    Sarma, Ganapathy N; Moody, Issa S; Ilouz, Ronit; Phan, Ryan H; Sankaran, Banumathi; Hall, Randy A; Taylor, Susan S

    2015-01-01

    A-kinase anchoring proteins (AKAPs) regulate cAMP-dependent protein kinase (PKA) signaling in space and time. Dual-specific AKAP2 (D-AKAP2/AKAP10) binds with high affinity to both RI and RII regulatory subunits of PKA and is anchored to transporters through PDZ domain proteins. Here, we describe a structure of D-AKAP2 in complex with two interacting partners and the exact mechanism by which a segment that on its own is disordered presents an α-helix to PKA and a β-strand to PDZK1. These two motifs nucleate a polyvalent scaffold and show how PKA signaling is linked to the regulation of transporters. Formation of the D-AKAP2: PKA binary complex is an important first step for high affinity interaction with PDZK1, and the structure reveals important clues toward understanding this phenomenon. In contrast to many other AKAPs, D-AKAP2 does not interact directly with the membrane protein. Instead, the interaction is facilitated by the C-terminus of D-AKAP2, which contains two binding motifs-the D-AKAP2AKB and the PDZ motif-that are joined by a short linker and only become ordered upon binding to their respective partner signaling proteins. The D-AKAP2AKB binds to the D/D domain of the R-subunit and the C-terminal PDZ motif binds to a PDZ domain (from PDZK1) that serves as a bridging protein to the transporter. This structure also provides insights into the fundamental question of why D-AKAP2 would exhibit a differential mode of binding to the two PKA isoforms. PMID:25348485

  19. Active impedance matching of complex structural systems

    NASA Technical Reports Server (NTRS)

    Macmartin, Douglas G.; Miller, David W.; Hall, Steven R.

    1991-01-01

    Viewgraphs on active impedance matching of complex structural systems are presented. Topics covered include: traveling wave model; dereverberated mobility model; computation of dereverberated mobility; control problem: optimal impedance matching; H2 optimal solution; statistical energy analysis (SEA) solution; experimental transfer functions; interferometer actuator and sensor locations; active strut configurations; power dual variables; dereverberation of complex structure; dereverberated transfer function; compensators; and relative power flow.

  20. Single-step solvothermal synthesis of mesoporous Ag-TiO2-reduced graphene oxide ternary composites with enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Arif Sher Shah, Md. Selim; Zhang, Kan; Park, A. Reum; Kim, Kwang Su; Park, Nam-Gyu; Park, Jong Hyeok; Yoo, Pil J.

    2013-05-01

    With growing interest in the photocatalytic performance of TiO2-graphene composite systems, the ternary phase of TiO2, graphene, and Ag is expected to exhibit improved photocatalytic characteristics because of the improved recombination rate of photogenerated charge carriers and potential contribution of the generation of localized surface plasmon resonance at Ag sites on a surface of the TiO2-graphene binary matrix. In this work, Ag-TiO2-reduced graphene oxide ternary nanocomposites were successfully synthesized by a simple solvothermal process. In a single-step synthetic procedure, the reduction of AgNO3 and graphene oxide and the hydrolysis of titanium tetraisopropoxide were spontaneously performed in a mixed solvent system of ethylene glycol, N,N-dimethylformamide and a stoichiometric amount of water without resorting to the use of typical reducing agents. The nanocomposites were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, along with different microscopic and spectroscopic techniques, enabling us to confirm the successful reduction of AgNO3 and graphite oxide to metallic Ag and reduced graphene oxide, respectively. Due to the highly facilitated electron transport of well distributed Ag nanoparticles, the synthesized ternary nanocomposite showed enhanced photocatalytic activity for degradation of rhodamine B dye under visible light irradiation.With growing interest in the photocatalytic performance of TiO2-graphene composite systems, the ternary phase of TiO2, graphene, and Ag is expected to exhibit improved photocatalytic characteristics because of the improved recombination rate of photogenerated charge carriers and potential contribution of the generation of localized surface plasmon resonance at Ag sites on a surface of the TiO2-graphene binary matrix. In this work, Ag-TiO2-reduced graphene oxide ternary nanocomposites were successfully synthesized by a simple solvothermal process. In a single-step synthetic procedure, the reduction

  1. Crystal structure of a benzo[a]pyrene diol epoxide adduct in a ternary complex with a DNA polymerase.

    PubMed

    Ling, Hong; Sayer, Jane M; Plosky, Brian S; Yagi, Haruhiko; Boudsocq, François; Woodgate, Roger; Jerina, Donald M; Yang, Wei

    2004-02-24

    The first occupation-associated cancers to be recognized were the sooty warts (cancers of the scrotum) suffered by chimney sweeps in 18th century England. In the 19th century, high incidences of skin cancers were noted among fuel industry workers. By the early 20th century, malignant skin tumors were produced in laboratory animals by repeatedly painting them with coal tar. The culprit in coal tar that induces cancer was finally isolated in 1933 and determined to be benzo[a]pyrene (BP), a polycyclic aromatic hydrocarbon. A residue of fuel and tobacco combustion and frequently ingested by humans, BP is metabolized in mammals to benzo[a]pyrene diol epoxide (BPDE), which forms covalent DNA adducts and induces tumor growth. In the 70 yr since its isolation, BP has been the most studied carcinogen. Yet, there has been no crystal structure of a BPDE DNA adduct. We report here the crystal structure of a BPDE-adenine adduct base-paired with thymine at a template-primer junction and complexed with the lesion-bypass DNA polymerase Dpo4 and an incoming nucleotide. Two conformations of the BPDE, one intercalated between base pairs and another solvent-exposed in the major groove, are observed. The latter conformation, which can be stabilized by organic solvents that reduce the dielectric constant, seems more favorable for DNA replication by Dpo4. These structures also suggest a mechanism by which mutations are generated during replication of DNA containing BPDE adducts. PMID:14982998

  2. Antischistosomal Activity of Oxindolimine-Metal Complexes

    PubMed Central

    Dario, Bruno S.; Couto, Ricardo A. A.; Pinto, Pedro L. S.; da Costa Ferreira, Ana M.

    2015-01-01

    In recent years, a class of oxindole-copper and -zinc complex derivatives have been reported as compounds with efficient proapoptotic activity toward different tumor cells (e.g., neuroblastomas, melanomas, monocytes). Here we assessed the efficacy of synthesized oxindole-copper(II), -zinc(II), and -vanadyl (VO2+) complexes against adult Schistosoma mansoni worms. The copper(II) complexes (50% inhibitory concentrations of 30 to 45 μM) demonstrated greater antischistosomal properties than the analogous zinc and vanadyl complexes regarding lethality, reduction of motor activity, and oviposition. PMID:26239976

  3. Antischistosomal Activity of Oxindolimine-Metal Complexes.

    PubMed

    de Moraes, Josué; Dario, Bruno S; Couto, Ricardo A A; Pinto, Pedro L S; da Costa Ferreira, Ana M

    2015-10-01

    In recent years, a class of oxindole-copper and -zinc complex derivatives have been reported as compounds with efficient proapoptotic activity toward different tumor cells (e.g., neuroblastomas, melanomas, monocytes). Here we assessed the efficacy of synthesized oxindole-copper(II), -zinc(II), and -vanadyl (VO(2+)) complexes against adult Schistosoma mansoni worms. The copper(II) complexes (50% inhibitory concentrations of 30 to 45 μM) demonstrated greater antischistosomal properties than the analogous zinc and vanadyl complexes regarding lethality, reduction of motor activity, and oviposition. PMID:26239976

  4. Protein synthesis in brine shrimp embryos and rabbit reticulocytes. The effect of Mg2+ on binary (eukaryotic initiation factor 2 X GDP) and ternary (eukaryotic initiation factor 2 X GTP X met-tRNAf) complex formation.

    PubMed

    Mehta, H B; Woodley, C L; Wahba, A J

    1983-03-25

    We have prepared eukaryotic initiation factor 2 (eIF-2) from rabbit reticulocytes and Artemia embryos and studied the effect of Mg2+ on binary (eIF-2 X GDP) and ternary (eIF-2 X GTP X Met-tRNAf) complex formation. Under conditions where Mg2+ inhibits Met-tRNAf binding to reticulocyte eIF-2, ternary complex formation with Artemia eIF-2 is not inhibited. Similarly, the formation of eIF-2 X GDP with Artemia eIF-2 is stimulated by Mg2+, whereas the corresponding reticulocyte binary complex is strongly inhibited. In the presence of 1 mM Mg2+, the isolated Artemia eIF-2 X GDP complex is stable in the absence of any added nucleotide, but readily exchanges bound GDP for free GTP. However, the reticulocyte eIF-2 X GDP complex is significantly more stable in the presence of GTP, and nucleotide exchange is dependent upon the addition of a factor isolated from either the postribosomal supernatant or the high salt wash of rabbit reticulocyte ribosomes. This factor also stimulates Met-tRNAf binding to both Artemia and reticulocyte eIF-2. PMID:6550599

  5. A new ternary ruthenium(III) complex with 1,3-bis(salicylideneamino) propan-2-ol and 3-picolylamine: Synthesis, characterization, density functional theory and preparation of electrochemical sensor for nitrite analysis

    NASA Astrophysics Data System (ADS)

    Terbouche, Achour; Ait-Ramdane-Terbouche, Chafia; Djebbar, Safia; Guerniche, Djamila; Bagtache, Radia; Bensiradj, Nour El Houda; Saal, Amar; Hauchard, Didier

    2014-11-01

    A novel electrochemical sensor based on graphite (G) functionalised with a new ternary ruthenium(III) complex was developed and applied to detect nitrite in aqueous solution. The Ru(III) complex was synthesized using 1,3-bis(salicylideneamino) propan-2-ol polydentate Schiff base (BSAP) and 3-Picolylamine (PLA), and was characterized by elemental analysis, Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible spectrophotometry (UV-Visible), gradient-assisted hetero nuclear single quantum coherence spectroscopy (gHSQC) and cyclic voltammetry technique. In addition, the structure of the synthesized complex was optimized using density functional theory (DFT). The results showed that the ternary Ru(III)-BSAP-PLA complex was formed and the adapted structure was an tetrahedral geometry. The electrochemical behavior of nitrite at the sensor prepared using G/Ru(III)-BSAP-PLA composite shows that the evaluated electron transfer coefficient (α = 0.83) indicates a very significant electrocatalytic mechanism for oxidation of nitrite in the presence of the Ru(III)-BSAP-PLA complex. Comparing to other published works, the sensor developed using G/Ru(III)-BSAP-PLA exhibited low limit of detection (LOD = 1.81 μM) around pH = 7.

  6. Safe and effective delivery of small interfering RNA with polymer- and liposomes-based complexes.

    PubMed

    Kodama, Yukinobu; Harauchi, Satoe; Kawanabe, Saki; Ichikawa, Nobuhiro; Nakagawa, Hiroo; Muro, Takahiro; Higuchi, Norihide; Nakamura, Tadahiro; Kitahara, Takashi; Sasaki, Hitoshi

    2013-01-01

    We developed binary and ternary complexes based on polymers and liposomes for safe and effective delivery of small interfering RNA (siRNA). Anti-luciferase siRNA was used as a model of nucleic acid medicine. The binary complexes of siRNA were prepared with cationic polymers and cationic liposomes such as polyethylenimine (PEI), polyamidoamine (PAMAM) dendrimer, poly-L-arginine (PLA), trimethyl[2,3-(dioleoxy)-propyl]ammonium chloride (DOTMA), and cholesteryl 3β-N-(dimetylaminnoethyl)carbamate hydrochloride (DC-Chol). The ternary complexes were constructed by the addition of γ-polyglutamic acid (γ-PGA) to the binary complexes. The complexes were approximately 54-153 nm in particle size. The binary complexes showed a cationic surface charge although an anionic surface charge was observed in the ternary complexes. The polymer-based complexes did not show a silencing effect in the mouse colon carcinoma cell line expressing luciferase regularly (Colon26/Luc cells). The binary complexes based on liposomes and their ternary complexes coated by γ-PGA showed a significant silencing effect. The binary complexes showed significant cytotoxicity although the ternary complexes coated by γ-PGA did not show significant cytotoxicity. The ternary complexes coated by γ-PGA suppressed luciferase activity in the tumor after their direct injection into the tumors of mice bearing Colon26/Luc cells. Thus, we have newly identified safe and efficient ternary complexes of siRNA for clinical use. PMID:23727920

  7. 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

  8. Synthesis and crystal structure of copper (II) uracil ternary polymeric complex with 1,10-phenanthroline along with the Hirshfeld surface analysis of the metal binding sites for the uracil ligand

    NASA Astrophysics Data System (ADS)

    Patil, Yogesh Prakash; Nethaji, Munirathinam

    2015-02-01

    The study of models for "metal-enzyme-substrate" interaction has been a proactive area of research owing to its biological and pharmacological importance. In this regard the ternary copper uracil complex with 1,10-phenanthroline represents metal-enzyme-substrate system for DNA binding enzymes. The synthesis of the complex, followed by slow evaporation of the reaction mixture forms two concomitant solvatomorph crystals viz., {[Cu(phen)(μ-ura)(H2O)]n·H2O (1a)} and {[Cu(phen)(μ-ura)(H2O)]n·CH3OH (1b)}. Both complexes are structurally characterized, while elemental analysis, IR and EPR spectra were recorded for 1b (major product). In both complexes, uracil coordinates uniquely via N1 and N3 nitrogen atom acting as a bidentate bridging ligand forming a 1-D polymer. The two solvatomorphs were quantitatively analyzed for the differences with the aid of Hirshfeld surface analysis.

  9. Antiretroviral activity of thiosemicarbazone metal complexes.

    PubMed

    Pelosi, Giorgio; Bisceglie, Franco; Bignami, Fabio; Ronzi, Paola; Schiavone, Pasqualina; Re, Maria Carla; Casoli, Claudio; Pilotti, Elisabetta

    2010-12-23

    Thiosemicarbazones display a wide antimicrobial activity by targeting bacteria, fungi, and viruses. Here, we report our studies on the antiviral activity of two thiosemicarbazone metal complexes, [bis(citronellalthiosemicarbazonato)nickel(II)] and [aqua(pyridoxalthiosemicarbazonato)copper(II)] chloride monohydrate, against the retroviruses HIV-1 and HTLV-1/-2. Both compounds exhibit antiviral properties against HIV but not against HTLVs . In particular, the copper complex shows the most potent anti-HIV activity by acting at the post-entry steps of the viral cycle. PMID:21121632

  10. Functional interplay of DnaE polymerase, DnaG primase and DnaC helicase within a ternary complex, and primase to polymerase hand-off during lagging strand DNA replication in Bacillus subtilis

    PubMed Central

    Rannou, Olivier; Le Chatelier, Emmanuelle; Larson, Marilynn A.; Nouri, Hamid; Dalmais, Bérengère; Laughton, Charles; Jannière, Laurent; Soultanas, Panos

    2013-01-01

    Bacillus subtilis has two replicative DNA polymerases. PolC is a processive high-fidelity replicative polymerase, while the error-prone DnaEBs extends RNA primers before hand-off to PolC at the lagging strand. We show that DnaEBs interacts with the replicative helicase DnaC and primase DnaG in a ternary complex. We characterize their activities and analyse the functional significance of their interactions using primase, helicase and primer extension assays, and a ‘stripped down’ reconstituted coupled assay to investigate the coordinated displacement of the parental duplex DNA at a replication fork, synthesis of RNA primers along the lagging strand and hand-off to DnaEBs. The DnaG–DnaEBs hand-off takes place after de novo polymerization of only two ribonucleotides by DnaG, and does not require other replication proteins. Furthermore, the fidelity of DnaEBs is improved by DnaC and DnaG, likely via allosteric effects induced by direct protein–protein interactions that lower the efficiency of nucleotide mis-incorporations and/or the efficiency of extension of mis-aligned primers in the catalytic site of DnaEBs. We conclude that de novo RNA primer synthesis by DnaG and initial primer extension by DnaEBs are carried out by a lagging strand–specific subcomplex comprising DnaG, DnaEBs and DnaC, which stimulates chromosomal replication with enhanced fidelity. PMID:23563155

  11. Impact of the nature and size of the polymeric backbone on the ability of heterobifunctional ligands to mediate shiga toxin and serum amyloid p component ternary complex formation.

    PubMed

    Kitov, Pavel I; Paszkiewicz, Eugenia; Sadowska, Joanna M; Deng, Zhicheng; Ahmed, Marya; Narain, Ravin; Griener, Thomas P; Mulvey, George L; Armstrong, Glen D; Bundle, David R

    2011-09-01

    Inhibition of AB(5)-type bacterial toxins can be achieved by heterobifunctional ligands (BAITs) that mediate assembly of supramolecular complexes involving the toxin's pentameric cell membrane-binding subunit and an endogenous protein, serum amyloid P component, of the innate immune system. Effective in vivo protection from Shiga toxin Type 1 (Stx1) is achieved by polymer-bound, heterobifunctional inhibitors-adaptors (PolyBAITs), which exhibit prolonged half-life in circulation and by mediating formation of face-to-face SAP-AB(5) complexes, block receptor recognition sites and redirect toxins to the spleen and liver for degradation. Direct correlation between solid-phase activity and protective dose of PolyBAITs both in the cytotoxicity assay and in vivo indicate that the mechanism of protection from intoxication is inhibition of toxin binding to the host cell membrane. The polymeric scaffold influences the activity not only by clustering active binding fragments but also by sterically interfering with the supramolecular complex assembly. Thus, inhibitors based on N-(2-hydroxypropyl) methacrylamide (HPMA) show significantly lower activity than polyacrylamide-based analogs. The detrimental steric effect can partially be alleviated by extending the length of the spacer, which separates pendant ligand from the backbone, as well as extending the spacer, which spans the distance between binding moieties within each heterobifunctional ligand. Herein we report that polymer size and payload of the active ligand had moderate effects on the inhibitor's activity. PMID:22069757

  12. Impact of the Nature and Size of the Polymeric Backbone on the Ability of Heterobifunctional Ligands to Mediate Shiga Toxin and Serum Amyloid P Component Ternary Complex Formation

    PubMed Central

    Kitov, Pavel I.; Paszkiewicz, Eugenia; Sadowska, Joanna M.; Deng, Zhicheng; Ahmed, Marya; Narain, Ravin; Griener, Thomas P.; Mulvey, George L.; Armstrong, Glen D.; Bundle, David R.

    2011-01-01

    Inhibition of AB5-type bacterial toxins can be achieved by heterobifunctional ligands (BAITs) that mediate assembly of supramolecular complexes involving the toxin’s pentameric cell membrane-binding subunit and an endogenous protein, serum amyloid P component, of the innate immune system. Effective in vivo protection from Shiga toxin Type 1 (Stx1) is achieved by polymer-bound, heterobifunctional inhibitors-adaptors (PolyBAITs), which exhibit prolonged half-life in circulation and by mediating formation of face-to-face SAP-AB5 complexes, block receptor recognition sites and redirect toxins to the spleen and liver for degradation. Direct correlation between solid-phase activity and protective dose of PolyBAITs both in the cytotoxicity assay and in vivo indicate that the mechanism of protection from intoxication is inhibition of toxin binding to the host cell membrane. The polymeric scaffold influences the activity not only by clustering active binding fragments but also by sterically interfering with the supramolecular complex assembly. Thus, inhibitors based on N-(2-hydroxypropyl) methacrylamide (HPMA) show significantly lower activity than polyacrylamide-based analogs. The detrimental steric effect can partially be alleviated by extending the length of the spacer, which separates pendant ligand from the backbone, as well as extending the spacer, which spans the distance between binding moieties within each heterobifunctional ligand. Herein we report that polymer size and payload of the active ligand had moderate effects on the inhibitor’s activity. PMID:22069757

  13. Origin of Active Oxygen in a Ternary CuOx /Co3O4–CeO 2 Catalyst for CO Oxidation

    DOE PAGESBeta

    Liu, Zhigang; Wu, Zili; Peng, Xihong; Binder, Andrew; Chai, Songhai; Dai, Sheng

    2014-11-14

    In this paper, we have studied CO oxidation over a ternary CuOx/Co3O4-CeO2 catalyst and employed the techniques of N2 adsorption/desporption, XRD, TPR, TEM, in situ DRIFTS and QMS (Quadrupole mass spectrometer) to explore the origin of active oxygen. DRIFTS-QMS results with labeled 18O2 indicate that the origin of active oxygens in CuOx/Co3O4-CeO2 obeys a model, called as queue mechanism. Namely gas-phase molecular oxygens are dissociated to atomic oxygens and then incorporate in oxygen vacancies located at the interface of Co3O4-CeO2 to form active crystalline oxygens, and these active oxygens diffuse to the CO-Cu+ sites thanks to the oxygen vacancy concentrationmore » magnitude and react with the activated CO to form CO2. This process, obeying a queue rule, provides active oxygens to form CO2 from gas-phase O2 via oxygen vacancies and crystalline oxygen at the interface of Co3O4-CeO2.« less

  14. Collective dynamics of active filament complexes

    NASA Astrophysics Data System (ADS)

    Nogucci, Hironobu; Ishihara, Shuji

    2016-05-01

    Networks of biofilaments are essential for the formation of cellular structures that support various biological functions. For the most part, previous studies have investigated the collective dynamics of rodlike biofilaments; however, the shapes of the actual subcellular components are often more elaborate. In this study, we considered an active object composed of two active filaments, which represents the progression from rodlike biofilaments to complex-shaped biofilaments. Specifically, we numerically assessed the collective behaviors of these active objects in two dimensions and observed several types of dynamics, depending on the density and the angle of the two filaments as shape parameters of the object. Among the observed collective dynamics, a moving density band that we named a "moving smectic" is introduced here for the first time. By analyzing the trajectories of individual objects and the interactions among them, this study demonstrated how interactions among active biofilaments with complex shapes could produce collective dynamics in a nontrivial manner.

  15. The transcriptional corepressor DSP1 inhibits activated transcription by disrupting TFIIA-TBP complex formation.

    PubMed Central

    Kirov, N C; Lieberman, P M; Rushlow, C

    1996-01-01

    Transcriptional repression of eukaryotic genes is essential for many cellular and developmental processes, yet the precise mechanisms of repression remain poorly understood. The Dorsal Switch Protein (DSP1) was identified in a genetic screen for activities which convert Dorsal into a transcriptional repressor. DSP1 shares structural homology with the HMG-1/2 family and inhibits activation by the rel transcription factors Dorsal and NF-kappaB in transfection studies. Here we investigate the mechanism of transcriptional repression by DSP1. We found that DSP1 protein can act as a potent transcriptional repressor for multiple activator families in vitro and in transfection studies. DSP1 bound directly to the TATA binding protein (TBP), and formed a stable ternary complex with TBP bound to DNA. DSP1 preferentially disrupted the DNA binding of TBP complexes containing TFIIA and displaced TFIIA from binding to TBP. Consistent with the inhibition of TFIIA-bound complexes, DSP1 was shown to inhibit activated but not basal transcription reactions in vitro. The ability of DSP1 to interact with TBP and to repress transcription was mapped to the carboxy-terminal domain which contains two HMG boxes. Our results support the model that DSP1 represses activated transcription by interfering with the binding of TFIIA, a general transcription factor implicated in activated transcription pathways. Images PMID:9003783

  16. Linking Complexity with Cultural Historical Activity Theory

    ERIC Educational Resources Information Center

    McMurtry, Angus

    2006-01-01

    This paper explores the similarities and differences between complexity science's and cultural-historical activity theory's understandings of human learning. Notable similarities include their emphasis on the importance of social systems or collectives in understanding human knowledge and practices, as well as their characterization of systems'…

  17. Structure of the Dcp2-Dcp1 mRNA-decapping complex in the activated conformation.

    PubMed

    Valkov, Eugene; Muthukumar, Sowndarya; Chang, Chung-Te; Jonas, Stefanie; Weichenrieder, Oliver; Izaurralde, Elisa

    2016-06-01

    The removal of the mRNA 5' cap (decapping) by Dcp2 shuts down translation and commits mRNA to full degradation. Dcp2 activity is enhanced by activator proteins such as Dcp1 and Edc1. However, owing to conformational flexibility, the active conformation of Dcp2 and the mechanism of decapping activation have remained unknown. Here, we report a 1.6-Å-resolution crystal structure of the Schizosaccharomyces pombe Dcp2-Dcp1 heterodimer in an unprecedented conformation that is tied together by an intrinsically disordered peptide from Edc1. In this ternary complex, an unforeseen rotation of the Dcp2 catalytic domain allows residues from both Dcp2 and Dcp1 to cooperate in RNA binding, thus explaining decapping activation by increased substrate affinity. The architecture of the Dcp2-Dcp1-Edc1 complex provides a rationale for the conservation of a sequence motif in Edc1 that is also present in unrelated decapping activators, thus indicating that the presently described mechanism of decapping activation is evolutionarily conserved. PMID:27183195

  18. EPCR-dependent PAR2 activation by the blood coagulation initiation complex regulates LPS-triggered interferon responses in mice

    PubMed Central

    Liang, Hai Po H.; Kerschen, Edward J.; Hernandez, Irene; Basu, Sreemanti; Zogg, Mark; Botros, Fady; Jia, Shuang; Hessner, Martin J.; Griffin, John H.; Ruf, Wolfram

    2015-01-01

    Infection and inflammation are invariably associated with activation of the blood coagulation mechanism, secondary to the inflammation-induced expression of the coagulation initiator tissue factor (TF) on innate immune cells. By investigating the role of cell-surface receptors for coagulation factors in mouse endotoxemia, we found that the protein C receptor (ProcR; EPCR) was required for the normal in vivo and in vitro induction of lipopolysaccharide (LPS)-regulated gene expression. In cultured bone marrow–derived myeloid cells and in monocytic RAW264.7 cells, the LPS-induced expression of functionally active TF, assembly of the ternary TF-VIIa-Xa initiation complex of blood coagulation, and the EPCR-dependent activation of protease-activated receptor 2 (PAR2) by the ternary TF-VIIa-Xa complex were required for the normal LPS induction of messenger RNAs encoding the TLR3/4 signaling adaptor protein Pellino-1 and the transcription factor interferon regulatory factor 8. In response to in vivo challenge with LPS, mice lacking EPCR or PAR2 failed to fully initiate an interferon-regulated gene expression program that included the Irf8 target genes Lif, Iigp1, Gbp2, Gbp3, and Gbp6. The inflammation-induced expression of TF and crosstalk with EPCR, PAR2, and TLR4 therefore appear necessary for the normal evolution of interferon-regulated host responses. PMID:25733582

  19. Enhancement of bioavailability and anthelmintic efficacy of albendazole by solid dispersion and cyclodextrin complexation techniques.

    PubMed

    Kalaiselvan, R; Mohanta, G P; Madhusudan, S; Manna, P K; Manavalan, R

    2007-08-01

    The objective of this study was to improve the oral bioavailability and therapeutic efficacy of albendazole (ABZ) employing solid dispersion and cyclodextrin complexation techniques. Solid dispersion (dispersion) was prepared using ABZ and polyvinylpyrrolidone (PVP) polymer (1:1 weight ratio). Ternary inclusion complex (ternary complex) was prepared using ABZ, hydroxypropyl beta-cyclodextrin (HPbetaCD) and L-tartaric acid (1:1:1 molar ratio). In rabbits with high gastric acidity (gastric pH approximately 1), ternary complex and solid dispersion showed a bioavailability enhancement of 3.2 and 2.4 fold respectively, compared to a commercial suspension (p < 0.05). The rise in gastric pH (pH > 5) caused a 62% reduction in AUC (area under the plasma level curve) for the commercial suspension, whereas the reduction in case of PVP dispersion and ternary complex was only 43% and 37% respectively. The rapid absorption of the drug from solid dispersion and ternary complex was reflected in improved anthelmintic efficacy against the systemic phases of Trichinella spiralis. The ternary complex was significantly more efficient than solid dispersion and exhibited the highest larvicidal activity (90%) at a dose of 50 mg x kg(-1) (p < 0.05). These results suggest that the bioavailability and therapeutic efficacy of the ternary complex might be high even if there is a great variation in the gastric pH. PMID:17867556

  20. One-pot synthesis of ternary Ag₂CO₃/Ag/AgCl photocatalyst in natural geothermal water with enhanced photocatalytic activity under visible light irradiation.

    PubMed

    Yao, Xiaxi; Liu, Xiaoheng

    2014-09-15

    Geothermal water is a clean, cheap and renewable resource and it is widely distributed all over the world. In this work, ternary Ag2CO3/Ag/AgCl photocatalyst has been successfully synthesized via a one-pot precipitation method in natural geothermal water at room temperature, wherein the geothermal water serves as the source of chlorine and carbonate. The results suggest that the Ag/AgCl nanoparticles are anchored on the surface of Ag2CO3 and Ag2CO3/Ag/AgCl composite shows strong absorption ability in the visible light region. The evaluation of the photocatalytic activity indicates that the as-synthesized Ag2CO3/Ag/AgCl photocatalyst exhibits higher photocatalytic performance for the degradation of methylene blue (MB) aqueous solution under visible light irradiation than one-component (Ag2CO3), two-component (Ag/AgCl, Ag2CO3/AgCl) and the mechanical mixture of Ag2CO3 and Ag/AgCl. The trapping experiments confirmed that holes (h(+)) and (•)O2(-) were the two main active species in the photocatalytic process. Finally, a possible Z-scheme photocatalytic mechanism of the charge transfer was proposed for the enhanced photocatalytic performance. This work may open up new insights into the application of cheap geothermal water resources in the word and provide new opportunities for facile fabrication of Ag/AgCl-based photocatalysts. PMID:25164388

  1. Ternary fission of superheavy elements

    NASA Astrophysics Data System (ADS)

    Balasubramaniam, M.; Vijayaraghavan, K. R.; Manimaran, K.

    2016-01-01

    Ternary fission of superheavy nuclei is studied within the three-cluster model potential energy surfaces (PESs). Due to shell effects, the stability of superheavy nuclei has been predicted to be associated with Z =114 , 120, and 126 for protons and N =184 for neutrons. Taking some representative nuclei we have extended the ternary fission studies to superheavy nuclei. We adopted two minimization procedures to minimize the potential and considered different arrangements of the fragments. The PES from one-dimensional minimization reveals a strong cluster region favoring various ternary breakups for an arrangement in which the lightest fragment is kept at the center. The PES obtained from two-dimensional minimization reveals strong preference of ternary fragmentation in the true ternary fission region. Though the dominant decay mode of superheavy nuclei is α decay, the α -accompanied ternary breakup is found to be a nonfavorable one. Further, the prominent ternary combinations are found to be associated with the neutron magic number.

  2. Ultrasonic-assisted preparation of novel ternary ZnO/Ag3VO4/Ag2CrO4 nanocomposites and their enhanced visible-light activities in degradation of different pollutants

    NASA Astrophysics Data System (ADS)

    Pirhashemi, Mahsa; Habibi-Yangjeh, Aziz

    2016-05-01

    Novel ternary ZnO/Ag3VO4/Ag2CrO4 nanocomposites were successfully fabricated via preparation of ZnO/Ag3VO4 followed by coupling of it with Ag2CrO4 through facile ultrasonic-assisted method. The resultant samples were carefully characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive analysis of X-rays, UV-vis diffuse reflectance spectroscopy, Fourier transform-infrared spectroscopy, and photoluminescence techniques. Photocatalytic activity for degradation of organic dyes, including rhodamine B, methylene blue, and methyl orange was examined under visible-light irradiation. Among the prepared samples, the ternary nanocomposite with 20% of Ag2CrO4 demonstrated the superior activity. This nanocomposite showed 10.6, 2.9, and 3.0-folds greater activity compared to ZnO, ZnO/Ag2CrO4, and ZnO/Ag3VO4, respectively. The enhanced activity was attributed to more harvesting of the visible-light irradiation and efficiently separation of the photogenerated charge carriers in the ternary nanocomposites. To understand efficiently separation of the charge carriers, a plausible diagram was proposed based on formation of tandem n-n heterojunctions.

  3. Dynamic studies of H-Ras•GTPγS interactions with nucleotide exchange factor Sos reveal a transient ternary complex formation in solution

    PubMed Central

    Vo, Uybach; Vajpai, Navratna; Embrey, Kevin J.; Golovanov, Alexander P.

    2016-01-01

    The cycling between GDP- and GTP- bound forms of the Ras protein is partly regulated by the binding of Sos. The structural/dynamic behavior of the complex formed between activated Sos and Ras at the point of the functional cycle where the nucleotide exchange is completed has not been described to date. Here we show that solution NMR spectra of H-Ras∙GTPγS mixed with a functional fragment of Sos (SosCat) at a 2:1 ratio are consistent with the formation of a rather dynamic assembly. H-Ras∙GTPγS binding was in fast exchange on the NMR timescale and retained a significant degree of molecular tumbling independent of SosCat, while SosCat also tumbled largely independently of H-Ras. Estimates of apparent molecular weight from both NMR data and SEC-MALS revealed that, at most, only one H-Ras∙GTPγS molecule appears stably bound to Sos. The weak transient interaction between Sos and the second H-Ras∙GTPγS may provide a necessary mechanism for complex dissociation upon the completion of the native GDP → GTP exchange reaction, but also explains measurable GTP → GTP exchange activity of Sos routinely observed in in vitro assays that use fluorescently-labelled analogs of GTP. Overall, the data presents the first dynamic snapshot of Ras functional cycle as controlled by Sos. PMID:27412770

  4. Dynamic studies of H-Ras•GTPγS interactions with nucleotide exchange factor Sos reveal a transient ternary complex formation in solution.

    PubMed

    Vo, Uybach; Vajpai, Navratna; Embrey, Kevin J; Golovanov, Alexander P

    2016-01-01

    The cycling between GDP- and GTP- bound forms of the Ras protein is partly regulated by the binding of Sos. The structural/dynamic behavior of the complex formed between activated Sos and Ras at the point of the functional cycle where the nucleotide exchange is completed has not been described to date. Here we show that solution NMR spectra of H-Ras∙GTPγS mixed with a functional fragment of Sos (Sos(Cat)) at a 2:1 ratio are consistent with the formation of a rather dynamic assembly. H-Ras∙GTPγS binding was in fast exchange on the NMR timescale and retained a significant degree of molecular tumbling independent of Sos(Cat), while Sos(Cat) also tumbled largely independently of H-Ras. Estimates of apparent molecular weight from both NMR data and SEC-MALS revealed that, at most, only one H-Ras∙GTPγS molecule appears stably bound to Sos. The weak transient interaction between Sos and the second H-Ras∙GTPγS may provide a necessary mechanism for complex dissociation upon the completion of the native GDP → GTP exchange reaction, but also explains measurable GTP → GTP exchange activity of Sos routinely observed in in vitro assays that use fluorescently-labelled analogs of GTP. Overall, the data presents the first dynamic snapshot of Ras functional cycle as controlled by Sos. PMID:27412770

  5. Control of the efficiency of agonist-induced information transfer and stability of the ternary complex containing the delta opioid receptor and the alpha subunit of G(i1) by mutation of a receptor/G protein contact interface.

    PubMed

    Moon, H E; Bahia, D S; Cavalli, A; Hoffmann, M; Milligan, G

    2001-09-01

    Fusion proteins were constructed between the delta opioid receptor and forms of the alpha subunit of G(i1) in which cysteine(351) was mutated to a range of amino acids. GDP reduced the binding of the agonist [(3)H]DADLE but not the antagonist [(3)H]naltrindole to both the receptor alone and all the delta opioid receptor-Cys(351)XaaG(i1)alpha fusion proteins. For the fusion proteins the pEC(50) for GDP was strongly correlated with the n-octanol/H(2)O partition co-efficient of G protein residue(351). Fusion proteins in which this residue was either isoleucine or glycine had similar observed binding kinetics for [(3)H]DADLE. However, the rate of dissociation of [(3)H]DADLE was substantially greater for the glycine-containing fusion protein than that containing isoleucine, indicating that more hydrophobic residues imbued greater stability to the agonist-receptor-G protein ternary complex. This resulted in a higher affinity of binding of [(3)H]DADLE to the fusion protein containing isoleucine(351). In expectation with the binding data, maximal DADLE-stimulated GTP hydrolysis by the isoleucine(351)-containing fusion protein was two-fold greater and the potency of DADLE seven-fold higher than for the version containing glycine. These results demonstrate that the stability of the ternary complex between delta opioid receptor, G(i1)alpha and an agonist (but not antagonist) ligand is dependent upon the nature of residue(351) of the G protein and that this determines the effectiveness of information flow from the receptor to the G protein. PMID:11522323

  6. 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.

  7. Complex networks in brain electrical activity

    NASA Astrophysics Data System (ADS)

    Ray, C.; Ruffini, G.; Marco-Pallarés, J.; Fuentemilla, L.; Grau, C.

    2007-08-01

    This letter reports a method to extract a functional network of the human brain from electroencephalogram measurements. A network analysis was performed on the resultant network and the statistics of the cluster coefficient, node degree, path length, and physical distance of the links, were studied. Even given the low electrode count of the experimental data the method was able to extract networks with network parameters that clearly depend on the type of stimulus presented to the subject. This type of analysis opens a door to studying the cerebral networks underlying brain electrical activity, and links the fields of complex networks and cognitive neuroscience.

  8. Active matter transport on complex substrates

    NASA Astrophysics Data System (ADS)

    Olson Reichhardt, C. J.; Ray, D.; Reichhardt, C.

    2014-09-01

    Colloids interacting with complex landscapes created by optical means exhibit a remarkable variety of novel orderings and equilibrium states. It is also possible to study nonequilibrium properties for colloids driven over optical traps when there is an additional external electric field or some other form of external driving. Recently a new type of colloidal system has been realized in which the colloids are self-driven or self-motile and undergo a persistent random walk. Self motile particle systems fall into the broader class of self-driven systems called active matter. For the case of externally driven colloidal particles moving over random or periodic arrangements of traps, various types of pinning or jamming effects can arise. Far less is known about the mobility of active matter particles in the presence or random or periodic substrates. For example, it is not known whether increasing the activity of the particles would reduce the jamming effects caused by effective friction between particles. Here we show by varying the activity and the density of active particles that various types of motion can arise. In some cases, increasing the self-driving leads to a reduction in the net flow of particles through the system.

  9. Efficient visible-light photocatalytic activity by band alignment in mesoporous ternary polyoxometalate-Ag2S-CdS semiconductors

    NASA Astrophysics Data System (ADS)

    Kornarakis, I.; Lykakis, I. N.; Vordos, N.; Armatas, G. S.

    2014-07-01

    Porous multicomponent semiconductor materials show improved photocatalytic performance due to the large and accessible pore surface area and high charge separation efficiency. Here we report the synthesis of well-ordered porous polyoxometalate (POM)-Ag2S-CdS hybrid mesostructures featuring a controllable composition and high photocatalytic activity via a two-step hard-templating and topotactic ion-exchange chemical process. Ag2S compounds and polyoxometalate cluster anions with different reduction potentials, such as PW12O403-, SiW12O404- and PMo12O403-, were employed as electron acceptors in these ternary heterojunction photocatalysts. Characterization by small-angle X-ray scattering, X-ray diffraction, transmission electron microscopy and N2 physisorption measurements showed hexagonal arrays of POM-Ag2S-CdS hybrid nanorods with large internal BET surface areas and uniform mesopores. The Keggin structure of the incorporated POM clusters was also verified by elemental X-ray spectroscopy microanalysis, infrared and diffuse-reflectance ultraviolet-visible spectroscopy. These new porous materials were implemented as visible-light-driven photocatalysts, displaying exceptional high activity in aerobic oxidation of various para-substituted benzyl alcohols to the corresponding carbonyl compounds. Our experiments show that the spatial separation of photogenerated electrons and holes at CdS through the potential gradient along the CdS-Ag2S-POM interfaces is responsible for the increased photocatalytic activity.Porous multicomponent semiconductor materials show improved photocatalytic performance due to the large and accessible pore surface area and high charge separation efficiency. Here we report the synthesis of well-ordered porous polyoxometalate (POM)-Ag2S-CdS hybrid mesostructures featuring a controllable composition and high photocatalytic activity via a two-step hard-templating and topotactic ion-exchange chemical process. Ag2S compounds and polyoxometalate cluster

  10. Biological activity of ruthenium nitrosyl complexes.

    PubMed

    Tfouni, Elia; Truzzi, Daniela Ramos; Tavares, Aline; Gomes, Anderson Jesus; Figueiredo, Leonardo Elias; Franco, Douglas Wagner

    2012-01-01

    Nitric oxide plays an important role in various biological processes, such as neurotransmission, blood pressure control, immunological responses, and antioxidant action. The control of its local concentration, which is crucial for obtaining the desired effect, can be achieved with exogenous NO-carriers. Coordination compounds, in particular ruthenium(III) and (II) amines, are good NO-captors and -deliverers. The chemical and photochemical properties of several ruthenium amine complexes as NO-carriers in vitro and in vivo have been reviewed. These nitrosyl complexes can stimulate mice hippocampus slices, promote the lowering of blood pressure in several in vitro and in vivo models, and control Trypanosoma cruzi and Leishmania major infections, and they are also effective against tumor cells in different models of cancer. These complexes can be activated chemically or photochemically, and the observed biological effects can be attributed to the presence of NO in the compound. Their efficiencies are explained on the basis of the [Ru(II)NO(+)](3+)/[Ru(II)NO(0)](2+) reduction potential, the specific rate constant for NO liberation from the [RuNO](2+) moiety, and the quantum yield of NO release. PMID:22178685

  11. Highly Robust Hybrid Photocatalyst for Carbon Dioxide Reduction: Tuning and Optimization of Catalytic Activities of Dye/TiO2/Re(I) Organic-Inorganic Ternary Systems.

    PubMed

    Won, Dong-Il; Lee, Jong-Su; Ji, Jung-Min; Jung, Won-Jo; Son, Ho-Jin; Pac, Chyongjin; Kang, Sang Ook

    2015-10-28

    Herein we report a detailed investigation of a highly robust hybrid system (sensitizer/TiO2/catalyst) for the visible-light reduction of CO2 to CO; the system comprises 5'-(4-[bis(4-methoxymethylphenyl)amino]phenyl-2,2'-dithiophen-5-yl)cyanoacrylic acid as the sensitizer and (4,4'-bis(methylphosphonic acid)-2,2'-bipyridine)Re(I)(CO)3Cl as the catalyst, both of which have been anchored on three different types of TiO2 particles (s-TiO2, h-TiO2, d-TiO2). It was found that remarkable enhancements in the CO2 conversion activity of the hybrid photocatalytic system can be achieved by addition of water or such other additives as Li(+), Na(+), and TEOA. The photocatalytic CO2 reduction efficiency was enhanced by approximately 300% upon addition of 3% (v/v) H2O, giving a turnover number of ≥570 for 30 h. A series of Mott-Schottky (MS) analyses on nanoparticle TiO2 films demonstrated that the flat-band potential (V(fb)) of TiO2 in dry DMF is substantially negative but positively shifts to considerable degrees in the presence of water or Li(+), indicating that the enhancement effects of the additives on the catalytic activity should mainly arise from optimal alignment of the TiO2 V(fb) with respect to the excited-state oxidation potential of the sensitizer and the reduction potential of the catalyst in our ternary system. The present results confirm that the TiO2 semiconductor in our heterogeneous hybrid system is an essential component that can effectively work as an electron reservoir and as an electron transporting mediator to play essential roles in the persistent photocatalysis activity of the hybrid system in the selective reduction of CO2 to CO. PMID:26456369

  12. Crystal Structure of Binary and Ternary Complexes of Archaeal UDP-galactose 4-Epimerase-like l-Threonine Dehydrogenase from Thermoplasma volcanium*

    PubMed Central

    Yoneda, Kazunari; Sakuraba, Haruhiko; Araki, Tomohiro; Ohshima, Toshihisa

    2012-01-01

    A gene from the thermophilic archaeon Thermoplasma volcanium encoding an l-threonine dehydrogenase (l-ThrDH) with a predicted amino acid sequence that was remarkably similar to the sequence of UDP-galactose 4-epimerase (GalE) was overexpressed in Escherichia coli, and its product was purified and characterized. The expressed enzyme was moderately thermostable, retaining more than 90% of its activity after incubation for 10 min at up to 70 °C. The catalytic residue was assessed using site-directed mutagenesis, and Tyr137 was found to be essential for catalysis. To clarify the structural basis of the catalytic mechanism, four different crystal structures were determined using the molecular replacement method: l-ThrDH-NAD+, l-ThrDH in complex with NAD+ and pyruvate, Y137F mutant in complex with NAD+ and l-threonine, and Y137F in complex with NAD+ and l-3-hydroxynorvaline. Each monomer consisted of a Rossmann-fold domain and a C-terminal catalytic domain, and the fold of the catalytic domain showed notable similarity to that of the GalE-like l-ThrDH from the psychrophilic bacterium Flavobacterium frigidimaris KUC-1. The substrate binding model suggests that the reaction proceeds through abstraction of the β-hydroxyl hydrogen of l-threonine via direct proton transfer driven by Tyr137. The factors contributing to the thermostability of T. volcanium l-ThrDH were analyzed by comparing its structure to that of F. frigidimaris l-ThrDH. This comparison showed that the presence of extensive inter- and intrasubunit ion pair networks are likely responsible for the thermostability of T. volcanium l-ThrDH. This is the first description of the molecular basis for the substrate recognition and thermostability of a GalE-like l-ThrDH. PMID:22374996

  13. Quantifying the Complexity of Flaring Active Regions

    NASA Astrophysics Data System (ADS)

    Stark, B.; Hagyard, M. J.

    1997-05-01

    While solar physicists have a better understanding of the importance magnetic fields play in the solar heating mechanism, it is still not possible to predict whether or when an active region will flare. In recent decades, qualitative studies of the changes in active region morphology have shown that there is generally an increase in the complexity of the spatial configuration of a solar active region leading up to a flare event. In this study, we quantify the spatial structure of the region using the Differential Box-Counting Method (DBC)of fractal analysis. We analyze data from NASA/Marshall Space Flight Center's vector magnetograph from two flaring active regions: AR 6089 from June 10, 1990, which produced one M1.7 flare, and AR 6659 from June 8, 9 and 10, 1991, this data set including one C5.7 and two M(6.4 and 3.2) flares. (AR 6659 produced several other flares). Several magnetic parameters are studied, including the transverse and longitudinal magnetic field components (Bt and Bl), the total field (Bmag), and the magnetic shear, which describes the non-potentiality of the field. Results are presented for the time series of magnetograms in relation to the timing of flare events.

  14. Quantifying the Complexity of Flaring Active Regions

    NASA Technical Reports Server (NTRS)

    Stark, B.; Hagyard, M. J.

    1997-01-01

    While solar physicists have a better understanding of the importance magnetic fields play in the solar heating mechanism, it is still not possible to predict whether or when an active region will flare. In recent decades, qualitative studies of the changes in active region morphology have shown that there is generally an increase in the complexity of the spatial configuration of a solar active region leading up to a flare event. In this study, we quantify the spatial structure of the region using the differential Box-Counting Method (DBC) of fractal analysis. We analyze data from NASA/Marshall Space Flight Centr's vector magnetograph from two flaring active regions: AR 6089 from June 10, 1990, which produced one M1.7 flare, and AR 6659 from June 8, 9 and 10, 1991, this data set including one C5.7 and two M(6.4 and 3.2) flare. (AR 6659 produced several other flares). Several magnetic parameters are studied, including the transverse and longitudinal magnetic field components (Bt and B1), the total field (Bmag), and the magnetic shear, which describes the non-potentiality of the field. Results are presented for the time series of magnetograms in relation to the timing of flare events.

  15. Clusterization in Ternary Fission

    NASA Astrophysics Data System (ADS)

    Kamanin, D. V.; Pyatkov, Y. V.

    This lecture notes are devoted to the new kind of ternary decay of low excited heavy nuclei called by us "collinear cluster tri-partition" (CCT) due to the features of the effect observed, namely, decay partners fly away almost collinearly and at least one of them has magic nucleon composition. At the early stage of our work the process of "true ternary fission" (fission of the nucleus into three fragments of comparable masses) was considered to be undiscovered for low excited heavy nuclei. Another possible prototype—three body cluster radioactivity—was also unknown. The most close to the CCT phenomenon, at least cinematically, stands so called "polar emission", but only very light ions (up to isotopes of Be) were observed so far.

  16. Ternary drop collisions

    NASA Astrophysics Data System (ADS)

    Hinterbichler, Hannes; Planchette, Carole; Brenn, Günter

    2015-10-01

    It has been recently proposed to use drop collisions for producing advanced particles or well-defined capsules, or to perform chemical reactions where the merged drops constitute a micro-reactor. For all these promising applications, it is essential to determine whether the merged drops remain stable after the collision, forming a single entity, or if they break up. This topic, widely investigated for binary drop collisions of miscible and immiscible liquid, is quite unexplored for ternary drop collisions. The current study aims to close this gap by experimentally investigating collisions between three equal-sized drops of the same liquid arranged centri-symmetrically. Three drop generators are simultaneously operated to obtain controlled ternary drop collisions. The collision outcomes are observed via photographs and compared to those of binary collisions. Similar to binary collisions, a regime map is built, showing coalescence and bouncing as well as reflexive and stretching separation. Significant differences are observed in the transitions between these regimes.

  17. Cu(II)-catalyzed reactions in ternary [Cu(AA)(AA - H)]+ complexes (AA = Gly, Ala, Val, Leu, Ile, t-Leu, Phe).

    PubMed

    Wang, Ping; Ohanessian, Gilles; Wesdemiotis, Chrys

    2009-01-01

    The unimolecular chemistry of [Cu(II)AA(AA - H)](+) complexes, composed of an intact and a deprotonated amino acid (AA) ligand, have been probed in the gas phase by tandem and multistage mass spectrometry in an electrospray ionization quadrupole ion trap mass spectrometer. The amino acids examined include Gly, Ala, Val, Leu, Ile, t-Leu and Phe. Upon collisionally-activated dissociation (CAD), the [Cu(II)AA(AA - H)](+) complexes undergo decarboxylation with simultaneous reduction of Cu(II) to Cu(I); during this process, a radical site is created at the alpha-carbon of the decarboxylated ligand (H(2)N(1) - (*)C(alpha)H - C(beta)H(2) - R; R = side chain substituent). The radical site is able to move along the backbone of the decarboxylated amino acid to form two new radicals (HN(1)(*) - C(alpha)H(2) - C(beta)H(2) - R and H(2)N(1) - C(alpha)H(2) - (*)C(beta)H - R). From the complexes of Gly and t-Leu, only C(alpha) and N(1) radicals can be formed. The whole radical ligand can be lost to form [Cu(I)AA](+) from these three isomeric radicals. Alternatively, further radical induced dissociations can take place along the backbone of the decarboxylated amino acid ligand to yield [Cu(II)AA(AA - 2H - CO(2))](+), [Cu(I)AA((*)NH(2))](+), [Cu(I)AA(HN = C(alpha)H(2))](+), or [Cu(I)AA(H(2)N - C(alpha)H = C(beta)H - R'](+) (R' = partial side chain substituent). The sodiated copper complexes, [Cu(II)(AA - H + Na)(AA - H)](+), show the same fragmentation patterns as their non-sodiated counterparts; sodium ion is retained on the intact amino acid ligand and is not involved in the CAD pathways. The amino groups of both AA units, the carbonyl group of the intact amino acid, and the deprotonated hydroxyl oxygen coordinate Cu(II) in square-planar fashion. Ab initio calculations indicate that the metal ion facilitates hydrogen atom shuttling between the N(1), C(alpha) and C(beta) atoms of the decarboxylated amino acid ligand. The dissociations of the decarboxylated radical ions unveil

  18. Ultrasonically assisted hydrothermal synthesis of activated carbon-HKUST-1-MOF hybrid for efficient simultaneous ultrasound-assisted removal of ternary organic dyes and antibacterial investigation: Taguchi optimization.

    PubMed

    Azad, F Nasiri; Ghaedi, M; Dashtian, K; Hajati, S; Pezeshkpour, V

    2016-07-01

    Activated carbon (AC) composite with HKUST-1 metal organic framework (AC-HKUST-1 MOF) was prepared by ultrasonically assisted hydrothermal method and characterized by FTIR, SEM and XRD analysis and laterally was applied for the simultaneous ultrasound-assisted removal of crystal violet (CV), disulfine blue (DSB) and quinoline yellow (QY) dyes in their ternary solution. In addition, this material, was screened in vitro for their antibacterial actively against Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PAO1) bacteria. In dyes removal process, the effects of important variables such as initial concentration of dyes, adsorbent mass, pH and sonication time on adsorption process optimized by Taguchi approach. Optimum values of 4, 0.02g, 4min, 10mgL(-1) were obtained for pH, AC-HKUST-1 MOF mass, sonication time and the concentration of each dye, respectively. At the optimized condition, the removal percentages of CV, DSB and QY were found to be 99.76%, 91.10%, and 90.75%, respectively, with desirability of 0.989. Kinetics of adsorption processes follow pseudo-second-order model. The Langmuir model as best method with high applicability for representation of experimental data, while maximum mono layer adsorption capacity for CV, DSB and QY on AC-HKUST-1 estimated to be 133.33, 129.87 and 65.37mgg(-1) which significantly were higher than HKUST-1 as sole material with Qm to equate 59.45, 57.14 and 38.80mgg(-1), respectively. PMID:26964963

  19. 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.

  20. 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

  1. The Crystal Structures of Ornithine Carbamoyltransferase From Mycobacterium Tuberculosis And Its Ternary Complex With Carbamoyl Phosphate And L-Norvaline Reveal the Enzyme's Catalytic Mechanism

    SciTech Connect

    Sankaranarayanan, R.; Cherney, M.M.; Cherney, L.T.; Garen, C.R.; Moradian, F.; James, M.N.G.

    2009-05-27

    Mycobacterium tuberculosis ornithine carbamoyltransferase (Mtb OTC) catalyzes the sixth step in arginine biosynthesis; it produces citrulline from carbamoyl phosphate (CP) and ornithine (ORN). Here, we report the crystal structures of Mtb OTC in orthorhombic (form I) and hexagonal (form II) space groups. The molecules in form II are complexed with CP and l-norvaline (NVA); the latter is a competitive inhibitor of OTC. The asymmetric unit in form I contains a pseudo hexamer with 32 point group symmetry. The CP and NVA in form II induce a remarkable conformational change in the 80s and the 240s loops with the displacement of these loops towards the active site. The displacement of these loops is strikingly different from that seen in other OTC structures. In addition, the ligands induce a domain closure of 4.4{sup o} in form II. Sequence comparison of active-site residues of Mtb OTC with several other OTCs of known structure reveals that they are virtually identical. The interactions involving the active-site residues of Mtb OTC with CP and NVA and a modeling study of ORN in the form II structure strongly rule out an earlier proposed mechanistic role of Cys264 in catalysis and suggest a possible mechanism for OTC. Our results strongly support the view that ORN with an already deprotonated N{sup {var_epsilon}} atom is the species that binds to the enzyme and that one of the phosphate oxygen atoms of CP is likely to be involved in accepting a proton from the doubly protonated N{sup {var_epsilon}} atom of ORN. We have interpreted this deprotonation as part of the collapse of the transition state of the reaction.

  2. Hydrogenation of biofuels with formic acid over a palladium-based ternary catalyst with two types of active sites.

    PubMed

    Wang, Liang; Zhang, Bingsen; Meng, Xiangju; Su, Dang Sheng; Xiao, Feng-Shou

    2014-06-01

    A composite catalyst including palladium nanoparticles on titania (TiO2) and on nitrogen-modified porous carbon (Pd/TiO2@N-C) is synthesized from palladium salts, tetrabutyl titanate, and chitosan. N2 sorption isotherms show that the catalyst has a high BET surface area (229 m(2)  g(-1)) and large porosity. XPS and TEM characterization of the catalyst shows that palladium species with different chemical states are well dispersed across the TiO2 and nitrogen-modified porous carbon, respectively. The Pd/TiO2@N-C catalyst is very active and shows excellent stability towards hydrogenation of vanillin to 2-methoxy-4-methylphenol using formic acid as hydrogen source. This activity can be attributed to a synergistic effect between the Pd/TiO2 (a catalyst for dehydrogenation of formic acid) and Pd/N-C (a catalyst for hydrogenation of vanillin) sites. PMID:24861954

  3. Variation in DNA binding constants with a change in geometry of ternary copper(II) complexes with N2O donor Schiff base and cyanate or dicyanamide

    NASA Astrophysics Data System (ADS)

    Jana, Subrata; Santra, Ramesh Chandra; Das, Saurabh; Chattopadhyay, Shouvik

    2014-09-01

    Two new copper(II) complexes, [Cu(L)(OCN)] (1) and [CuL(dca)]n (2), where HL = 2-(-(2-(diethylamino)ethylimino)methyl)naphthalen-1-ol, dca = N(CN)2-, have been synthesized and characterized by elemental analysis, IR, UV-VIS spectroscopy and single crystal X-ray diffraction studies. Complex 1 has square planar and complex 2 square pyramidal geometries in solid state around metal centre. Interactions of the complexes with calf thymus DNA (CT DNA) were studied by UV-VIS spectroscopy. Binding constant and site size of interaction were determined. Binding site size and intrinsic binding constant K revealed complex 1 interacted with calf thymus DNA better than complex 2.

  4. New ternary praseodymium germanides

    SciTech Connect

    Fedyna, M.F.; Pecharskii, V.K.; Bodak, O.I.

    1987-09-01

    Using the powder method (DRON-2.0 diffractometer; Fe K/sub ..cap alpha../ radiation; theta/2theta recording method, sin theta/sub max//lambda = 5 nm/sup -1/), the crystal structure of the ternary compounds Pr/sub 1-x/(NiGe)/sub 13/ (x = 0.24), Pr/sub 3/Ni/sub 4/Ge/sub 4/, Pr/sub 1-x/(CoGe)/sub 13/ (x = 0.31), Pr/sub 2/Co/sub 3/Ge/sub 5/, and PrFe/sub 1-x/Ge/sub 3/ (x = 0.46) were determined. The germanides P/sub 1-x/(NiGe)/sub 13/ and Pr/sub 1-x/(NiGe)/sub 13/ belong to the structural type of CeNi/sub 8.5/Si/sub 4.5/ and the ternary compounds Pr/sub 3/Ni/sub 4/Ge/sub 4/, Pr/sub 2/Co/sub 3/Ge/sub 5/, and PrFe/sub 1-x/Ge/sub 3/ crystallize in the structural types of U/sub 3/Ni/sub 4/Si/sub 4/, U/sub 2/Co/sub 3/Si/sub 5/, and BaNiSn/sub 3/. During investigations of the equilibrium phase diagrams of the systems Pr-/Fe, Co, Ni/-Ge, new ternary compounds were discovered, viz., Pr/sub 1-x/(NiGe)/sub 13/ (X = 0.24), Pr/sub 3/Ni/sub 4/Ge/sub 4/, Pr/sub 1-x/(CoGe)/sub 13/ (x = 0.31), Pr/sub 2/Co/sub 3/Ge/sub 5/, PrFe/sub 1-x/Ge/sub 3/ (x = 0.46).

  5. Crystal Structures of the Kinase Domain of the Sulfate-Activating Complex in Mycobacterium tuberculosis

    PubMed Central

    Poyraz, Ömer; Brunner, Katharina; Lohkamp, Bernhard; Axelsson, Hanna; Hammarström, Lars G. J.; Schnell, Robert; Schneider, Gunter

    2015-01-01

    In Mycobacterium tuberculosis the sulfate activating complex provides a key branching point in sulfate assimilation. The complex consists of two polypeptide chains, CysD and CysN. CysD is an ATP sulfurylase that, with the energy provided by the GTPase activity of CysN, forms adenosine-5’-phosphosulfate (APS) which can then enter the reductive branch of sulfate assimilation leading to the biosynthesis of cysteine. The CysN polypeptide chain also contains an APS kinase domain (CysC) that phosphorylates APS leading to 3’-phosphoadenosine-5’-phosphosulfate, the sulfate donor in the synthesis of sulfolipids. We have determined the crystal structures of CysC from M. tuberculosis as a binary complex with ADP, and as ternary complexes with ADP and APS and the ATP mimic AMP-PNP and APS, respectively, to resolutions of 1.5 Å, 2.1 Å and 1.7 Å, respectively. CysC shows the typical APS kinase fold, and the structures provide comprehensive views of the catalytic machinery, conserved in this enzyme family. Comparison to the structure of the human homolog show highly conserved APS and ATP binding sites, questioning the feasibility of the design of specific inhibitors of mycobacterial CysC. Residue Cys556 is part of the flexible lid region that closes off the active site upon substrate binding. Mutational analysis revealed this residue as one of the determinants controlling lid closure and hence binding of the nucleotide substrate. PMID:25807013

  6. A Ternary Polyaniline/Active Carbon/Lithium Iron Phosphate Composite as Cathode Material for Lithium Ion Battery.

    PubMed

    Wang, Xiaohong; Zhang, Wuxing; Huang, Yunhui; Xia, Tian; Lian, Yongfu

    2016-06-01

    Lithium iron phosphate (LiFePO4) has been evaluated as the most promising cathode material for the next generation lithium-ion batteries because of its high operating voltage, good cycle performance, low cost, and environmentally friendly safety. However, pure LiFePO4 shows poor reversible capacity and charge/discharge performance at high current density. Many methods including optimization of particle size, introduction of coating carbon and conductive polymer, and the doping of metal and halogen ions have been developed to improve its electrochemical performance. In this study, conductive polymer polyaniline (PANI), active carbon and LiFePO4 (C-LFP/PANI) composite cathodes were successfully prepared by chemical oxidation method. Electrochemical performance shows that a remarkable improvement in capacity and rate performance can be achieved in the C-LFP/PANI composite cathodes with an addition of HCI. In comparison with C-LFP cathode, the C-LFP/PANI doped with HCl composite exhibits ca. 15% and 26% capacity enhancement at 0.2 C and 10 C, respectively. PMID:27427742

  7. Insulin-stimulated expression of c-fos, fra1 and c-jun accompanies the activation of the activator protein-1 (AP-1) transcriptional complex.

    PubMed Central

    Griffiths, M R; Black, E J; Culbert, A A; Dickens, M; Shaw, P E; Gillespie, D A; Tavaré, J M

    1998-01-01

    The activator protein-1 (AP-1) transcriptional complex is made up of members of the Fos (c-Fos, FosB, Fra1, Fra2) and Jun (c-Jun, JunB, JunD) families and is stimulated by insulin in several cell types. The mechanism by which insulin activates this complex is not well understood but it is dependent on the activation of the Erk1 and Erk2 isoforms of mitogen-activated protein kinases. In the current study we show that the AP-1 complex isolated from insulin-stimulated cells contained c-Fos, Fra1, c-Jun and JunB. The activation of the AP-1 complex by insulin was accompanied by (i) a transient increase in c-fos expression, and the transactivation of the ternary complex factors Elk1 and Sap1a, in an Erk1/Erk2-dependent fashion; (ii) a substantial increase in the expression of Fra1 protein and mRNA, which was preceded by a transient decrease in its electrophoretic mobility upon SDS/PAGE, indicative of phosphorylation; and (iii) a sustained increase in c-jun expression without increasing c-Jun phosphorylation on serines 63 and 73 or activation of the stress-activated kinase JNK/SAPK. In conclusion, insulin appears to stimulate the activity of the AP-1 complex primarily through a change in the abundance of the components of this complex, although there may be an additional role for Fra1 phosphorylation. PMID:9742208

  8. Metal complexes of curcumin for cellular imaging, targeting, and photoinduced anticancer activity.

    PubMed

    Banerjee, Samya; Chakravarty, Akhil R

    2015-07-21

    Curcumin is a polyphenolic species. As an active ingredient of turmeric, it is well-known for its traditional medicinal properties. The therapeutic values include antioxidant, anti-inflammatory, antiseptic, and anticancer activity with the last being primarily due to inhibition of the transcription factor NF-κB besides affecting several biological pathways to arrest tumor growth and its progression. Curcumin with all these positive qualities has only remained a potential candidate for cancer treatment over the years without seeing any proper usage because of its hydrolytic instability involving the diketo moiety in a cellular medium and its poor bioavailability. The situation has changed considerably in recent years with the observation that curcumin in monoanionic form could be stabilized on binding to a metal ion. The reports from our group and other groups have shown that curcumin in the metal-bound form retains its therapeutic potential. This has opened up new avenues to develop curcumin-based metal complexes as anticancer agents. Zinc(II) complexes of curcumin are shown to be stable in a cellular medium. They display moderate cytotoxicity against prostate cancer and neuroblastoma cell lines. A similar stabilization and cytotoxic effect is reported for (arene)ruthenium(II) complexes of curcumin against a variety of cell lines. The half-sandwich 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1]decane (RAPTA)-type ruthenium(II) complexes of curcumin are shown to be promising cytotoxic agents with low micromolar concentrations for a series of cancer cell lines. In a different approach, cobalt(III) complexes of curcumin are used for its cellular delivery in hypoxic tumor cells using intracellular agents that reduce the metal and release curcumin as a cytotoxin. Utilizing the photophysical and photochemical properties of the curcumin dye, we have designed and synthesized photoactive curcumin metal complexes that are used for cellular imaging by fluorescence microscopy and

  9. Exploiting Complexity Information for Brain Activation Detection

    PubMed Central

    Zhang, Yan; Liang, Jiali; Lin, Qiang; Hu, Zhenghui

    2016-01-01

    We present a complexity-based approach for the analysis of fMRI time series, in which sample entropy (SampEn) is introduced as a quantification of the voxel complexity. Under this hypothesis the voxel complexity could be modulated in pertinent cognitive tasks, and it changes through experimental paradigms. We calculate the complexity of sequential fMRI data for each voxel in two distinct experimental paradigms and use a nonparametric statistical strategy, the Wilcoxon signed rank test, to evaluate the difference in complexity between them. The results are compared with the well known general linear model based Statistical Parametric Mapping package (SPM12), where a decided difference has been observed. This is because SampEn method detects brain complexity changes in two experiments of different conditions and the data-driven method SampEn evaluates just the complexity of specific sequential fMRI data. Also, the larger and smaller SampEn values correspond to different meanings, and the neutral-blank design produces higher predictability than threat-neutral. Complexity information can be considered as a complementary method to the existing fMRI analysis strategies, and it may help improving the understanding of human brain functions from a different perspective. PMID:27045838

  10. Exploiting Complexity Information for Brain Activation Detection.

    PubMed

    Zhang, Yan; Liang, Jiali; Lin, Qiang; Hu, Zhenghui

    2016-01-01

    We present a complexity-based approach for the analysis of fMRI time series, in which sample entropy (SampEn) is introduced as a quantification of the voxel complexity. Under this hypothesis the voxel complexity could be modulated in pertinent cognitive tasks, and it changes through experimental paradigms. We calculate the complexity of sequential fMRI data for each voxel in two distinct experimental paradigms and use a nonparametric statistical strategy, the Wilcoxon signed rank test, to evaluate the difference in complexity between them. The results are compared with the well known general linear model based Statistical Parametric Mapping package (SPM12), where a decided difference has been observed. This is because SampEn method detects brain complexity changes in two experiments of different conditions and the data-driven method SampEn evaluates just the complexity of specific sequential fMRI data. Also, the larger and smaller SampEn values correspond to different meanings, and the neutral-blank design produces higher predictability than threat-neutral. Complexity information can be considered as a complementary method to the existing fMRI analysis strategies, and it may help improving the understanding of human brain functions from a different perspective. PMID:27045838

  11. 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. PMID:27035619

  12. 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. PMID:21163688

  13. Stability constants of the ternary complexes of CuDTPA, NiDCTA, CrEDTA, CoHEEDTA, NiHEEDTA and CuHEEEDT Aheedta with OH-.

    PubMed

    Korsse, J; Leurs, G A; Louwrier, P W

    1985-06-01

    The acid dissociation constants of the metal chelates H(3)CuDTPA, H(2) NiDCTA, HCrEDTA, HCoHEEDTA, HNiHEEDTA and HCuHEEDTA were determined by potentiometric titration. The constants determined at an ionic strength of 0.1 were pK(a,1) = 2.1; pK(a,2) = 2.8 and pK(a,3) = 4.75 for H(3) CuDTPA (296 K), pK(a,1) = 2.16 for HCrEDTA (298 K); pK(a,1) = 1.6 and pK(a,2) = 2.0 for H(2) NiDCTA (298 K); pK(a,1) = 2.24 for HCoHEEDTA, pK(a,1) = 2.47 for HCuHEEDTA and pK(a,1) = 1.73 for HNi-HEEDTA. At high pH the formation of ternary hydroxo-complexes was observed for the chelates CrEDTA(-) (pK(a,1) = 7.35; pK(a,1) = 12.35), CoHEEDTA(-) (pK(a,1) = 11.74), NiHEEDTA(-) (pK(a,2) = 12,44) and CuHEEDTA(-) (pK(a,2) = 10.45). PMID:18963877

  14. RICE SALT SENSITIVE3 Forms a Ternary Complex with JAZ and Class-C bHLH Factors and Regulates Jasmonate-Induced Gene Expression and Root Cell Elongation[C][W

    PubMed Central

    Toda, Yosuke; Tanaka, Maiko; Ogawa, Daisuke; Kurata, Kyo; Kurotani, Ken-ichi; Habu, Yoshiki; Ando, Tsuyu; Sugimoto, Kazuhiko; Mitsuda, Nobutaka; Katoh, Etsuko; Abe, Kiyomi; Miyao, Akio; Hirochika, Hirohiko; Hattori, Tsukaho; Takeda, Shin

    2013-01-01

    Plasticity of root growth in response to environmental cues and stresses is a fundamental characteristic of land plants. However, the molecular basis underlying the regulation of root growth under stressful conditions is poorly understood. Here, we report that a rice nuclear factor, RICE SALT SENSITIVE3 (RSS3), regulates root cell elongation during adaptation to salinity. Loss of function of RSS3 only moderately inhibits cell elongation under normal conditions, but it provokes spontaneous root cell swelling, accompanied by severe root growth inhibition, under saline conditions. RSS3 is preferentially expressed in the root tip and forms a ternary complex with class-C basic helix-loop-helix (bHLH) transcription factors and JASMONATE ZIM-DOMAIN proteins, the latter of which are the key regulators of jasmonate (JA) signaling. The mutated protein arising from the rss3 allele fails to interact with bHLH factors, and the expression of a significant portion of JA-responsive genes is upregulated in rss3. These results, together with the known roles of JAs in root growth regulation, suggest that RSS3 modulates the expression of JA-responsive genes and plays a crucial role in a mechanism that sustains root cell elongation at appropriate rates under stressful conditions. PMID:23715469

  15. First examples of ternary lanthanide 5-aminoisophthalate complexes: Hydrothermal syntheses and structures of lanthanide coordination polymers with 5-aminoisophthalate and oxalate

    NASA Astrophysics Data System (ADS)

    Liu, Chong-Bo; Wen, Hui-Liang; Tan, Sheng-Shui; Yi, Xiu-Guang

    2008-05-01

    Two new lanthanide coordination polymers with mixed-carboxylates, [Ln(OX)(HAPA)(H 2O)] n[Ln = Eu ( 1), Ho ( 2); H 2APA = 5-aminoisophthalic acid; OX = oxalate] were obtained by hydrothermal reactions, and characterized by single crystal X-ray diffraction, elemental analysis and IR spectra. Complexes 1 and 2 are both 3-D supramolecular structure, in which lanthanide ions are bridged by oxalate and 5-aminoisophthalate ligands forming 2-D metal-organic framework, and 2-D networks are further architectured to form 3-D supramolecular structures by hydrogen bonds. The two carboxylate groups of H 2APA ligand are all deprotonated and exhibit chelating and bridging bidentate coordination modes, respectively, and the amino group in HAPA presents - NH3+ in the titled complexes. The thermogravimetric analysis was carried out to examine the thermal stability of the titled complexes. And the photoluminescence property of 1 was investigated.

  16. Properties of the manganese(II) binding site in ternary complexes of Mnter dot ADP and Mnter dot ATP with chloroplast coupling factor 1: Magnetic field dependence of solvent sup 1 H and sup 2 H NMR relaxation rates

    SciTech Connect

    Haddy, A.E.; Frasch, W.D.; Sharp, R.R. )

    1989-05-02

    The influence of the binding of ADP and ATP on the high-affinity Mn(II) binding site of chloroplast coupling factor 1 (CF{sub 1}) was studied by analysis of field-dependent solvent proton and deuteron spin-lattice relaxation data. In order to characterize metal-nucleotide complexes of CF{sub 1} under conditions similar to those of the NMR experiments, the enzyme was analyzed for bound nucleotides and Mn(II) after incubation with AdN and MnCl{sub 2} and removal of labile ligands by extensive gel filtration chromatography. In the field-dependent NMR experiments, the Mn(II) binding site of CF{sub 1} was studied for three mole ratios of added Mn(II) to CF{sub 1}, 0.5, 1.0, and 1.5, in the presence of an excess of either ADP or ATP. The results were extrapolated to zero Mn(II) concentration to characterize the environment of the first Mn(II) binding site of Cf{sub 1}. In the presence of both adenine nucleotides, pronounced changes in the Mn(II) environment relative to that in Mn(II)-CF{sub 1} were evident; the local relaxation rate maxima were more pronounced and shifted to higher field strengths, and the relaxation rate per bound Mn(II) increased at all field strengths. Analysis of the data revealed that the number of exchangeable water molecules liganded to bound Mn(II) increased from one in the binary Mn(II)-CF{sub 1} complex to three and two in the ternary Mn(II)-ADP-CF{sub 1} and Mn(II)-ATP-CF{sub 1} complexes, respectively; these results suggest that a water ligand to bound Mn(II) in the Mn(II)-ADP-CF{sub 1} complex is replaced by the {gamma}-phosphate of ATP in the Mn(II)-ATP-CF{sub 1} complex. A binding model is presented to account for these observations.

  17. Formation of ternary complexes by coordination of (diethylenetriamine)-platinum(II) to N1 or N7 of the adenine moiety of the antiviral nucleotide analogue 9.

    PubMed

    Kampf, G; Lüth, M S; Kapinos, L E; Müller, J; Holý, A; Lippert, B; Sigel, H

    2001-05-01

    The synthesis of (Dien)Pt(PMEA-N1), where Dien = diethylenetriamine and PMEA2- = dianion of 9-[2-(phosphonomethoxy)ethyl]adenine, is described. The acidity constants of the threefold protonated H3[(Dien)Pt(PMEA-N1)]3+ complex were determined and in part estimated (UV spectrophotometry and potentiometric pH titration): The release of the proton from the (N7)H+ site in H4[(Dien)Pt(PMEA-N1)]3+ occurs with a rather low pKa (= 0.52+/-0.10). The release of the proton from the -P(O)2(OH) group (pKa = 6.69+/-0.03) in H[(Dien)Pt(PMEA-N1)]+ is only slightly affected by the N1-coordinated (Dien)Pt2+ unit. Comparison with the acidic properties of the H[(Dien)Pt(PMEA-N7)]+ species provides evidence that in the (Dien)Pt(PMEA-N7) complex in aqueous solution an intramolecular, outer-sphere macrochelate is formed through hydrogen bonds between the -PO3(2-) residue of PMEA2- and a PtII-coordinated (Dien)NH2 group; its formation degree amounts to about 40%. The stability constants of the M[(Dien)Pt(PMEA-N1)]2+ complexes with M2+ = Mg2+, Ca2+, Ni2+, Cu2+ and Zn2+ were measured by potentiometric pH titrations in aqueous solution at 25 degrees C and I = 0.1 M (NaNO3). Application of previously determined straight-line plots of log K(M(R-PO3))M versus pK(H(R-PO3)H for simple phosph(on)ate ligands. R-PO3(2-), where R represents a non-inhibiting residue without an affinity for metal ions, proves that the primary binding site of (Dien)Pt(PMEA-N1) is the phosphonate group with all metal ions studied; in fact, Mg2+, Ca2+ and Ni2+ coordinate (within the error limits) only to this site. For the Cu[(Dien)Pt(PMEA-N1)]2+ and Zn[(Dien)Pt(PMEA-N1)]2- systems also the formation of five-membered chelates involving the ether oxygen of the -CH2-O-CH2-PO3(2-) residue could be detected; the formation degrees are about 60% and 30%, respectively. The metal-ion-binding properties of the isomeric (Dien)Pt(PMEA-N7) species studied previously differ in so far that the resulting M[(Dien)Pt(PMEA-N7)]2+ complexes

  18. Ternary boride product and process

    NASA Technical Reports Server (NTRS)

    Clougherty, Edward V. (Inventor)

    1976-01-01

    A hard, tough, strong ceramic body is formed by hot pressing a mixture of a powdered metal and a powdered metal diboride. The metal employed is zirconium, titanium or hafnium and the diboride is the diboride of a different member of the same group of zirconium, titanium or hafnium to form a ternary composition. During hot pressing at temperatures above about 2,000.degree.F., a substantial proportion of acicular ternary monoboride is formed.

  19. Experimental and Computational Studies of the Macrocyclic Effect of an Auxiliary Ligand on Electron and Proton Transfers Within Ternary Copper(II)–Histidine Complexes

    SciTech Connect

    Song, Tao; Lam, Corey; Ng, Dominic C.; Orlova, G.; Laskin, Julia; Fang, De-Cai; Chu, Ivan K.

    2009-06-01

    The dissociation of [CuII(L)His]•2+ complexes [L = diethylenetriamine (dien) or 1,4,7-triazacyclononane (9-aneN3)] bears a strong resemblance to the previously reported behavior of [CuII(L)GGH]•2+ complexes. We have used low energy collision-induced dissociation experiments and density functional theory (DFT) calculations at the B3LYP/6-31+G(d) level to study the macrocyclic effect of the auxiliary ligands on the formation of His•+ from prototypical [CuII(L)His]•2+ systems. DFT revealed that the relative energy barriers of the same electron transfer (ET) dissociation pathways of [CuII(9-aneN3)His]•2+ and [CuII(dien)His]•2+ are very similar, with the ET reactions of [CuII(9-aneN3)His]•2+ leading to the generation of two distinct His•+ species; in contrast, the proton transfer (PT) dissociation pathways of [CuII(9-aneN3)His]•2+ and [CuII(dien)His]•2+ differ considerably. The PT reactions of [CuII(9-aneN3)His]•2+ are associated with substantially higher barriers (>13 kcal/mol) than those of [CuII(dien)His]•2+. Thus, the sterically encumbered auxiliary 9-aneN3 ligand facilitates ET reactions while moderating PT reactions, allowing the formation of hitherto non-observable histidine radical cations.

  20. PqqD is a novel peptide chaperone that forms a ternary complex with the radical S-adenosylmethionine protein PqqE in the pyrroloquinoline quinone biosynthetic pathway.

    PubMed

    Latham, John A; Iavarone, Anthony T; Barr, Ian; Juthani, Prerak V; Klinman, Judith P

    2015-05-15

    Pyrroloquinoline quinone (PQQ) is a product of a ribosomally synthesized and post-translationally modified pathway consisting of five conserved genes, pqqA-E. PqqE is a radical S-adenosylmethionine (RS) protein with a C-terminal SPASM domain, and is proposed to catalyze the formation of a carbon-carbon bond between the glutamate and tyrosine side chains of the peptide substrate PqqA. PqqD is a 10-kDa protein with an unknown function, but is essential for PQQ production. Recently, in Klebsiella pneumoniae (Kp), PqqD and PqqE were shown to interact; however, the stoichiometry and KD were not obtained. Here, we show that the PqqE and PqqD interaction transcends species, also occurring in Methylobacterium extorquens AM1 (Me). The stoichiometry of the MePqqD and MePqqE interaction is 1:1 and the KD, determined by surface plasmon resonance spectroscopy (SPR), was found to be ∼12 μm. Moreover, using SPR and isothermal calorimetry techniques, we establish for the first time that MePqqD binds MePqqA tightly (KD ∼200 nm). The formation of a ternary MePqqA-D-E complex was captured by native mass spectrometry and the KD for the MePqqAD-MePqqE interaction was found to be ∼5 μm. Finally, using a bioinformatic analysis, we found that PqqD orthologues are associated with the RS-SPASM family of proteins (subtilosin, pyrroloquinoline quinone, anaerobic sulfatase maturating enzyme, and mycofactocin), all of which modify either peptides or proteins. In conclusion, we propose that PqqD is a novel peptide chaperone and that PqqD orthologues may play a similar role in peptide modification pathways that use an RS-SPASM protein. PMID:25817994

  1. PqqD Is a Novel Peptide Chaperone That Forms a Ternary Complex with the Radical S-Adenosylmethionine Protein PqqE in the Pyrroloquinoline Quinone Biosynthetic Pathway*

    PubMed Central

    Latham, John A.; Iavarone, Anthony T.; Barr, Ian; Juthani, Prerak V.; Klinman, Judith P.

    2015-01-01

    Pyrroloquinoline quinone (PQQ) is a product of a ribosomally synthesized and post-translationally modified pathway consisting of five conserved genes, pqqA-E. PqqE is a radical S-adenosylmethionine (RS) protein with a C-terminal SPASM domain, and is proposed to catalyze the formation of a carbon-carbon bond between the glutamate and tyrosine side chains of the peptide substrate PqqA. PqqD is a 10-kDa protein with an unknown function, but is essential for PQQ production. Recently, in Klebsiella pneumoniae (Kp), PqqD and PqqE were shown to interact; however, the stoichiometry and KD were not obtained. Here, we show that the PqqE and PqqD interaction transcends species, also occurring in Methylobacterium extorquens AM1 (Me). The stoichiometry of the MePqqD and MePqqE interaction is 1:1 and the KD, determined by surface plasmon resonance spectroscopy (SPR), was found to be ∼12 μm. Moreover, using SPR and isothermal calorimetry techniques, we establish for the first time that MePqqD binds MePqqA tightly (KD ∼200 nm). The formation of a ternary MePqqA-D-E complex was captured by native mass spectrometry and the KD for the MePqqAD-MePqqE interaction was found to be ∼5 μm. Finally, using a bioinformatic analysis, we found that PqqD orthologues are associated with the RS-SPASM family of proteins (subtilosin, pyrroloquinoline quinone, anaerobic sulfatase maturating enzyme, and mycofactocin), all of which modify either peptides or proteins. In conclusion, we propose that PqqD is a novel peptide chaperone and that PqqD orthologues may play a similar role in peptide modification pathways that use an RS-SPASM protein. PMID:25817994

  2. Molecular Dynamics Simulations and Structural Analysis to Decipher Functional Impact of a Twenty Residue Insert in the Ternary Complex of Mus musculus TdT Isoform

    PubMed Central

    Mutt, Eshita; Sowdhamini, Ramanathan

    2016-01-01

    Insertions/deletions are common evolutionary tools employed to alter the structural and functional repertoire of protein domains. An insert situated proximal to the active site or ligand binding site frequently impacts protein function; however, the effect of distal indels on protein activity and/or stability are often not studied. In this paper, we have investigated a distal insert, which influences the function and stability of a unique DNA polymerase, called terminal deoxynucleotidyl transferase (TdT). TdT (EC:2.7.7.31) is a monomeric 58 kDa protein belonging to family X of eukaryotic DNA polymerases and known for its role in V(D)J recombination as well as in non-homologous end-joining (NHEJ) pathways. Two murine isoforms of TdT, with a length difference of twenty residues and having different biochemical properties, have been studied. All-atom molecular dynamics simulations at different temperatures and interaction network analyses were performed on the short and long-length isoforms. We observed conformational changes in the regions distal to the insert position (thumb subdomain) in the longer isoform, which indirectly affects the activity and stability of the enzyme through a mediating loop (Loop1). A structural rationale could be provided to explain the reduced polymerization rate as well as increased thermosensitivity of the longer isoform caused by peripherally located length variations within a DNA polymerase. These observations increase our understanding of the roles of length variants in introducing functional diversity in protein families in general. PMID:27311013

  3. Changes in complex spike activity during classical conditioning.

    PubMed

    Rasmussen, Anders; Jirenhed, Dan-Anders; Wetmore, Daniel Z; Hesslow, Germund

    2014-01-01

    The cerebellar cortex is necessary for adaptively timed conditioned responses (CRs) in eyeblink conditioning. During conditioning, Purkinje cells acquire pause responses or "Purkinje cell CRs" to the conditioned stimuli (CS), resulting in disinhibition of the cerebellar nuclei (CN), allowing them to activate motor nuclei that control eyeblinks. This disinhibition also causes inhibition of the inferior olive (IO), via the nucleo-olivary pathway (N-O). Activation of the IO, which relays the unconditional stimulus (US) to the cortex, elicits characteristic complex spikes in Purkinje cells. Although Purkinje cell activity, as well as stimulation of the CN, is known to influence IO activity, much remains to be learned about the way that learned changes in simple spike firing affects the IO. In the present study, we analyzed changes in simple and complex spike firing, in extracellular Purkinje cell records, from the C3 zone, in decerebrate ferrets undergoing training in a conditioning paradigm. In agreement with the N-O feedback hypothesis, acquisition resulted in a gradual decrease in complex spike activity during the conditioned stimulus, with a delay that is consistent with the long N-O latency. Also supporting the feedback hypothesis, training with a short interstimulus interval (ISI), which does not lead to acquisition of a Purkinje cell CR, did not cause a suppression of complex spike activity. In contrast, observations that extinction did not lead to a recovery in complex spike activity and the irregular patterns of simple and complex spike activity after the conditioned stimulus are less conclusive. PMID:25140129

  4. DNA binding, nuclease activity, DNA photocleavage and cytotoxic properties of Cu(II) complexes of N-substituted sulfonamides.

    PubMed

    García-Giménez, José Luis; Hernández-Gil, Javier; Martínez-Ruíz, Aloma; Castiñeiras, Alfonso; Liu-González, Malva; Pallardó, Federico V; Borrás, Joaquín; Alzuet Piña, Gloria

    2013-04-01

    Ternary copper(II) complexes [Cu(NST)2(phen)] (1) and [Cu(NST)2(NH3)2]·H2O (2) [HNST=N-(4,5-dimethylthiazol-2-yl)naphthalene-1-sulfonamide] were prepared and characterized by physico-chemical techniques. Both 1 and 2 were structurally characterized by X-ray crystallography. The crystal structures show the presence of a distorted square planar CuN4 geometry in which the deprotonated sulfonamide, acting as monodentate ligand, binds to the metal ion through the thiazole N atom. Both complexes present intermolecular π-π stacking interactions between phenanthroline rings (compound 1) and between naphthalene rings (compound 2). The interaction of the complexes with CT DNA was studied by means of thermal denaturation, viscosity measurements and fluorescence spectroscopy. The complexes display good binding propensity to the calf thymus DNA giving the order: 1>2. Complex 1, which has a higher capability for binding to DNA, showed better nuclease activity than 2 in the presence of ascorbate/H2O2. Both the kinetics and the mechanism of the DNA cleavage reaction were investigated. Furthermore, complex 1 showed efficient photo-induced DNA cleavage activity on irradiation with UV light in the absence of any external reagent. The UV light induced DNA cleavage follows a photo-redox pathway with generation of hydroxyl radicals as reactive species. In addition, the cytotoxic properties of both complexes (1 and 2) were evaluated in human cancer cells (HeLa, Caco-2 and MDA-468). The low IC50 values, in particular those against Caco-2, have indicated that the compounds can be considered as promising chemotherapeutic agents. PMID:23384854

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

    SciTech Connect

    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.

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

    DOE PAGESBeta

    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, increasedmore » 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.« less

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

    PubMed

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

    2015-01-01

    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. PMID:26041586

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

    PubMed Central

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

    2015-01-01

    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. PMID:26041586

  9. Anticancer activity assessment of two novel binuclear platinum (II) complexes.

    PubMed

    Shahsavani, Mohammad Bagher; Ahmadi, Shamseddin; Aseman, Marzieh Dadkhah; Nabavizadeh, S Masoud; Rashidi, Mehdi; Asadi, Zahra; Erfani, Nasrollah; Ghasemi, Atiyeh; Saboury, Ali Akbar; Niazi, Ali; Bahaoddini, Aminollah; Yousefi, Reza

    2016-08-01

    In the current study, two binuclear Pt (II) complexes, containing cis, cis-[Me2Pt (μ-NN) (μ-dppm) PtMe2] (1), and cis,cis-[Me2Pt(μ-NN)(μ dppm) Pt((CH2)4)] (2) in which NN=phthalazine and dppm=bis (diphenylphosphino) methane were evaluated for their anticancer activities and DNA/purine nucleotide binding properties. These Pt (II) complexes, with the non-classical structures, demonstrated a significant anticancer activity against Jurkat and MCF-7 cancer cell lines. The results of ethidium bromide/acridine orange staining and Caspase-III activity suggest that these complexes were capable to stimulate an apoptotic mechanism of cell death in the cancer cells. Using different biophysical techniques and docking simulation analysis, we indicated that these complexes were also capable to interact efficiently with DNA via a non-intercalative mechanism. According to our results, substitution of cyclopentane (in complex 2) with two methyl groups (in complex 1) results in significant improvement of the complex ability to interact with DNA and subsequently to induce the anticancer activity. Overall, these binuclear Pt (II) complexes are promising group of the non-classical potential anticancer agents which can be considered as molecular templates in designing of highly efficient platinum anticancer drugs. PMID:27289447

  10. 17beta-estradiol-induced activation of ERK1/2 through endogenous androgen receptor-estradiol receptor alpha-Src complex in human prostate cells.

    PubMed

    Chieffi, Paolo; Kisslinger, Annamaria; Sinisi, Antonio A; Abbondanza, Ciro; Tramontano, Donatella

    2003-09-01

    We examined the effect of estrogens on mitogen-activated protein kinase (MAPK) in EPN cells, a line of epithelial cells derived from human normal prostate. 17beta-estradiol (E2) caused a rapid and transient activation of MAPK (ERK1/2) within 5 min. This effect was counteracted by the anti-estrogen ICI 182-780 and by MEK inhibitor PD098059. The activation of ERK1/2 through 17beta-estradiol triggered simultaneous association of endogenous androgen receptor, estrogen receptor alpha and Src. In addition, E2 stimulated the proliferation of EPN cells, suggesting that the formation of the ternary complex and the consequent activation of ERKs are implicated in the mechanism regulating proliferation of epithelial prostate cells. PMID:12888920

  11. A unique dinuclear mixed V(V) oxo-peroxo complex in the structural speciation of the ternary V(V)-peroxo-citrate system. potential mechanistic and structural insight into the aqueous synthetic chemistry of dinuclear V(V)-citrate species with H2O2.

    PubMed

    Kaliva, M; Gabriel, C; Raptopoulou, C P; Terzis, A; Voyiatzis, G; Zervou, M; Mateescu, C; Salifoglou, A

    2011-11-21

    Diverse vanadium biological activities entail complex interactions with physiological target ligands in aqueous media and constitute the crux of the undertaken investigation at the synthetic level. Facile aqueous redox reactions, as well as nonredox reactions, of V(III) and V(V) with physiological citric acid and hydrogen peroxide, under pH-specific conditions, led to the synthesis and isolation of a well-formed crystalline material upon the addition of ethanol as the precipitating solvent. Elemental analysis pointed to the molecular formulation (NH4)4[(VO2){VO(O2)}(C6H5O7)2]·1.5H2O (1). Complex 1 was further characterized by Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR), Raman spectroscopy, cyclic voltammetry, and X-ray crystallography. The crystallographic structure of 1 reveals the presence of the first dinuclear V(V)-citrate complex with non-peroxo- and peroxo-containing V(V) ions, concurrently present within the basic VV2O2 core. The nonperoxo unit VO2+ and the peroxo unit VO(O2)+ are each coordinated to a triply deprotonated citrate ligand in a distinct coordination mode and coordination geometry around the V(V) ions. These units are similar to those in homodinuclear complexes bearing oxo or peroxo groups. The unique assembly of both units in the anion of 1 renders the latter as a potential intermediate in the peroxidation process, from [V2O4(C6H5O7)2]4– to [V2O2(O2)2(C6H6O7)2]2–. The transformation reactions of 1 establish its connection with several V(V) and V(IV) dinuclear species present in the aqueous distribution of the V(IV,V)-citrate systems. The shown position of 1 as an intermediate in the mechanism of H2O2 addition to dinuclear V(V)-citrate species portends its role in the complex aqueous distribution of species in the ternary V(V)-peroxo-citrate system and its potential reactivity in (bio)chemically relevant media. PMID:22029259

  12. Structure of an argonaute silencing complex with a seed-containing guide DNA and target RNA duplex

    SciTech Connect

    Wang, Yanli; Juranek, Stefan; Li, Haitao; Sheng, Gang; Tuschl, Thomas; Patel, Dinshaw J.

    2009-01-08

    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 formation 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.

  13. Antifungal and Antioxidant Activities of Pyrrolidone Thiosemicarbazone Complexes

    PubMed Central

    Al-Amiery, Ahmed A.; Kadhum, Abdul Amir H.; Mohamad, Abu Bakar

    2012-01-01

    Metal complexes of (Z)-2-(pyrrolidin-2-ylidene)hydrazinecarbothioamide (L) with Cu(II), Co(II), and Ni(II) chlorides were tested against selected types of fungi and were found to have significant antifungal activities. The free-radical-scavenging ability of the metal complexes was determined by their interaction with the stable free radical 2,2′′-diphenyl-1-picrylhydrazyl, and all the compounds showed encouraging antioxidant activities. DFT calculations of the Cu complex were performed using molecular structures with optimized geometries. Molecular orbital calculations provide a detailed description of the orbitals, including spatial characteristics, nodal patterns, and the contributions of individual atoms. PMID:22400016

  14. Using activity theory to study cultural complexity in medical education.

    PubMed

    Frambach, Janneke M; Driessen, Erik W; van der Vleuten, Cees P M

    2014-06-01

    There is a growing need for research on culture, cultural differences and cultural effects of globalization in medical education, but these are complex phenomena to investigate. Socio-cultural activity theory seems a useful framework to study cultural complexity, because it matches current views on culture as a dynamic process situated in a social context, and has been valued in diverse fields for yielding rich understandings of complex issues and key factors involved. This paper explains how activity theory can be used in (cross-)cultural medical education research. We discuss activity theory's theoretical background and principles, and we show how these can be applied to the cultural research practice by discussing the steps involved in a cross-cultural study that we conducted, from formulating research questions to drawing conclusions. We describe how the activity system, the unit of analysis in activity theory, can serve as an organizing principle to grasp cultural complexity. We end with reflections on the theoretical and practical use of activity theory for cultural research and note that it is not a shortcut to capture cultural complexity: it is a challenge for researchers to determine the boundaries of their study and to analyze and interpret the dynamics of the activity system. PMID:24590549

  15. 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

  16. Preferential selection of isomer binding from chiral mixtures: alternate binding modes observed for the E and Z isomers of a series of 5-substituted 2,4-diaminofuro[2,3-d]pyrimidines as ternary complexes with NADPH and human dihydrofolate reductase

    SciTech Connect

    Cody, Vivian; Piraino, Jennifer; Pace, Jim; Li, Wei; Gangjee, Aleem

    2010-12-01

    The structures of six chirally mixed E/Z-isomers of 5-substituted 2,4-diaminofuro[2,3-d]pyrimidines reveals only one isomer is bound in the active site of human DHFR. The configuration of all but one C9-analogue is observed as the E-isomer. The crystal structures of six human dihydrofolate reductase (hDHFR) ternary complexes with NADPH and a series of mixed E/Z isomers of 5-substituted 5-[2-(2-methoxyphenyl)-prop-1-en-1-yl]furo[2,3-d]pyrimidine-2,4-diamines substituted at the C9 position with propyl, isopropyl, cyclopropyl, butyl, isobutyl and sec-butyl (E2–E7, Z3) were determined and the results were compared with the resolved E and Z isomers of the C9-methyl parent compound. The configuration of all of the inhibitors, save one, was observed as the E isomer, in which the binding of the furopyrimidine ring is flipped such that the 4-amino group binds in the 4-oxo site of folate. The Z3 isomer of the C9-isopropyl analog has the normal 2,4-diaminopyrimidine ring binding geometry, with the furo oxygen near Glu30 and the 4-amino group interacting near the cofactor nicotinamide ring. Electron-density maps for these structures revealed the binding of only one isomer to hDHFR, despite the fact that chiral mixtures (E:Z ratios of 2:1, 3:1 and 3:2) of the inhibitors were incubated with hDHFR prior to crystallization. Superposition of the hDHFR complexes with E2 and Z3 shows that the 2′-methoxyphenyl ring of E2 is perpendicular to that of Z3. The most potent inhibitor in this series is the isopropyl analog Z3 and the least potent is the isobutyl analog E6, consistent with data that show that the Z isomer makes the most favorable interactions with the active-site residues. The isobutyl moiety of E6 is observed in two orientations and the resultant steric crowding of the E6 analog is consistent with its weaker activity. The alternative binding modes observed for the furopyrimidine ring in these E/Z isomers suggest that new templates can be designed to probe these binding

  17. Ternary generalization of Heisenberg's algebra

    NASA Astrophysics Data System (ADS)

    Kerner, Richard

    2015-06-01

    A concise study of ternary and cubic algebras with Z3 grading is presented. We discuss some underlying ideas leading to the conclusion that the discrete symmetry group of permutations of three objects, S3, and its abelian subgroup Z3 may play an important role in quantum physics. We show then how most of important algebras with Z2 grading can be generalized with ternary composition laws combined with a Z3 grading. We investigate in particular a ternary, Z3-graded generalization of the Heisenberg algebra. It turns out that introducing a non-trivial cubic root of unity, , one can define two types of creation operators instead of one, accompanying the usual annihilation operator. The two creation operators are non-hermitian, but they are mutually conjugate. Together, the three operators form a ternary algebra, and some of their cubic combinations generate the usual Heisenberg algebra. An analogue of Hamiltonian operator is constructed by analogy with the usual harmonic oscillator, and some properties of its eigenfunctions are briefly discussed.

  18. New dirhodium complex with activity towards colorectal cancer.

    PubMed

    Frade, Raquel F M; Candeias, Nuno R; Duarte, Catarina M M; André, Vânia; Duarte, M Teresa; Gois, Pedro M P; Afonso, Carlos A M

    2010-06-01

    A novel dirhodium complex (Rh(2)(L-PheAla)(2)(OAc)(2) is reported with strong activity towards human colon adenocarcinoma cells. Its effect was not accompanied by generation of reactive oxygen species (ROS) neither by activation of caspase-3. PMID:20434912

  19. Origin of Active Oxygen in a Ternary CuOx /Co3O4–CeO 2 Catalyst for CO Oxidation

    SciTech Connect

    Liu, Zhigang; Wu, Zili; Peng, Xihong; Binder, Andrew; Chai, Songhai; Dai, Sheng

    2014-11-14

    In this paper, we have studied CO oxidation over a ternary CuOx/Co3O4-CeO2 catalyst and employed the techniques of N2 adsorption/desporption, XRD, TPR, TEM, in situ DRIFTS and QMS (Quadrupole mass spectrometer) to explore the origin of active oxygen. DRIFTS-QMS results with labeled 18O2 indicate that the origin of active oxygens in CuOx/Co3O4-CeO2 obeys a model, called as queue mechanism. Namely gas-phase molecular oxygens are dissociated to atomic oxygens and then incorporate in oxygen vacancies located at the interface of Co3O4-CeO2 to form active crystalline oxygens, and these active oxygens diffuse to the CO-Cu+ sites thanks to the oxygen vacancy concentration magnitude and react with the activated CO to form CO2. This process, obeying a queue rule, provides active oxygens to form CO2 from gas-phase O2 via oxygen vacancies and crystalline oxygen at the interface of Co3O4-CeO2.

  20. Antiparasitic activities of novel ruthenium/lapachol complexes.

    PubMed

    Barbosa, Marília I F; Corrêa, Rodrigo S; de Oliveira, Katia Mara; Rodrigues, Claudia; Ellena, Javier; Nascimento, Otaciro R; Rocha, Vinícius P C; Nonato, Fabiana R; Macedo, Taís S; Barbosa-Filho, José Maria; Soares, Milena B P; Batista, Alzir A

    2014-07-01

    The present study describes the synthesis, characterization, antileishmanial and antiplasmodial activities of novel diimine/(2,2'-bipyridine (bipy), 1,10-phenanthroline (phen), 4,4'-methylbipyridine (Me-bipy) and 4,4'-methoxybipyridine (MeO-bipy)/phosphine/ruthenium(II) complexes containing lapachol (Lap, 2-hydroxy-3-(3-33 methyl-2-buthenyl)-1,4-naphthoquinone) as bidentate ligand. The [Ru(Lap)(PPh3)2(bipy)]PF6 (1), [Ru(Lap)(PPh3)2(Me-bipy)]PF6 (2), [Ru(Lap)(PPh3)2(MeO-bipy)]PF6(3) and[Ru(Lap)(PPh3)2(phen)]PF6 (4) complexes, PPh3=triphenylphospine, were synthesized from the reactions of cis-[RuCl2(PPh3)2(X-bipy)] or cis-[RuCl2(PPh3)2(phen)], with lapachol. The [RuCl2(Lap)(dppb)] (5) [dppb=1,4-bis(diphenylphosphine)butane] was synthesized from the mer-[RuCl3(dppb)(H2O)] complex. The complexes were characterized by elemental analysis, molar conductivity, infrared and UV-vis spectroscopy, (31)P{(1)H} and (1)H NMR, and cyclic voltammetry. The Ru(III) complex, [RuCl2(Lap)(dppb)], was also characterized by the EPR technique. The structure of the complexes [Ru(Lap)(PPh3)2(bipy)]PF6 and [RuCl2(Lap)(dppb)] was elucidated by X-ray diffraction. The evaluation of the antiparasitic activities of the complexes against Leishmania amazonensis and Plasmodium falciparum demonstrated that lapachol-ruthenium complexes are more potent than the free lapachol. The [RuCl2(Lap)(dppb)] complex is the most potent and selective antiparasitic compound among the five new ruthenium complexes studied in this work, exhibiting an activity comparable to the reference drugs. PMID:24727183

  1. The Structure of the GM-CSF Receptor Complex Reveals a Distinct Mode of Cytokine Receptor Activation

    SciTech Connect

    Hansen, Guido; Hercus, Timothy R.; McClure, Barbara J.; Stomski, Frank C.; Dottore, Mara; Powell, Jason; Ramshaw, Hayley; Woodcock, Joanna M.; Xu, Yibin; Guthridge, Mark; McKinstry, William J.; Lopez, Angel F.; Parker, Michael W.

    2008-08-11

    Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic cytokine that controls the production and function of blood cells, is deregulated in clinical conditions such as rheumatoid arthritis and leukemia, yet offers therapeutic value for other diseases. Its receptors are heterodimers consisting of a ligand-specific {alpha} subunit and a {beta}c subunit that is shared with the interleukin (IL)-3 and IL-5 receptors. How signaling is initiated remains an enigma. We report here the crystal structure of the human GM-CSF/GM-CSF receptor ternary complex and its assembly into an unexpected dodecamer or higher-order complex. Importantly, mutagenesis of the GM-CSF receptor at the dodecamer interface and functional studies reveal that dodecamer formation is required for receptor activation and signaling. This unusual form of receptor assembly likely applies also to IL-3 and IL-5 receptors, providing a structural basis for understanding their mechanism of activation and for the development of therapeutics.

  2. Rhenium complexes with visible-light-induced anticancer activity.

    PubMed

    Kastl, Anja; Dieckmann, Sandra; Wähler, Kathrin; Völker, Timo; Kastl, Lena; Merkel, Anna Lena; Vultur, Adina; Shannan, Batool; Harms, Klaus; Ocker, Matthias; Parak, Wolfgang J; Herlyn, Meenhard; Meggers, Eric

    2013-06-01

    Shedding light on the matter: Rhenium(I) indolato complexes with highly potent visible-light-triggered antiproliferative activity (complex 1: EC50 light=0.1 μM vs EC50 dark=100 μM) in 2D- and 3D-organized cancer cells are reported and can be traced back to an efficient generation of singlet oxygen, causing rapid morphological changes and an induction of apoptosis. PMID:23568508

  3. Synthesis of Optically Active Polystyrene Catalyzed by Monophosphine Pd Complexes.

    PubMed

    Jouffroy, Matthieu; Armspach, Dominique; Matt, Dominique; Osakada, Kohtaro; Takeuchi, Daisuke

    2016-07-11

    Cationic Pd(II) monophosphine complexes derived from α- and β-cyclodextrins (CDs) promote the homopolymerization of styrene under carbon monoxide pressure. Although reversible CO coordination takes place under catalytic conditions according to (13) C NMR studies with (13) C-enriched CO, both complexes catalyze the formation of CO-free styrene polymers. These macromolecules display optical activity as a result of the presence of stereoregular sequences within the overall atactic polymer. PMID:27218801

  4. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

    DOE PAGESBeta

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; et al

    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

  5. Why are the 2-oxoacid dehydrogenase complexes so large? Generation of an active trimeric complex.

    PubMed

    Marrott, Nia L; Marshall, Jacqueline J T; Svergun, Dmitri I; Crennell, Susan J; Hough, David W; van den Elsen, Jean M H; Danson, Michael J

    2014-11-01

    The four-component polypeptides of the 2-oxoacid dehydrogenase complex from the thermophilic archaeon Thermoplasma acidophilum assemble to give an active multienzyme complex possessing activity with the branched-chain 2-oxoacids derived from leucine, isoleucine and valine, and with pyruvate. The dihydrolipoyl acyl-transferase (E2) core of the complex is composed of identical trimer-forming units that assemble into a novel 42-mer structure comprising octahedral and icosahedral geometric aspects. From our previously determined structure of this catalytic core, the inter-trimer interactions involve a tyrosine residue near the C-terminus secured in a hydrophobic pocket of an adjacent trimer like a ball-and-socket joint. In the present study, we have deleted the five C-terminal amino acids of the E2 polypeptide (IIYEI) and shown by equilibrium centrifugation that it now only assembles into a trimeric enzyme. This was confirmed by SAXS analysis, although this technique showed the presence of approximately 20% hexamers. The crystal structure of the trimeric truncated E2 core has been determined and shown to be virtually identical with the ones observed in the 42-mer, demonstrating that removal of the C-terminal anchor does not significantly affect the individual monomer or trimer structures. The truncated E2 is still able to bind both 2-oxoacid decarboxylase (E1) and dihydrolipoamide dehydrogenase (E3) components to give an active complex with catalytic activity similar to the native multienzyme complex. This is the first report of an active mini-complex for this enzyme, and raises the question of why all 2-oxoacid dehydrogenase complexes assemble into such large structures. PMID:25088564

  6. Active mixing of complex fluids at the microscale

    PubMed Central

    Ober, Thomas J.; Foresti, Daniele; Lewis, Jennifer A.

    2015-01-01

    Mixing of complex fluids at low Reynolds number is fundamental for a broad range of applications, including materials assembly, microfluidics, and biomedical devices. Of these materials, yield stress fluids (and gels) pose the most significant challenges, especially when they must be mixed in low volumes over short timescales. New scaling relationships between mixer dimensions and operating conditions are derived and experimentally verified to create a framework for designing active microfluidic mixers that can efficiently homogenize a wide range of complex fluids. Active mixing printheads are then designed and implemented for multimaterial 3D printing of viscoelastic inks with programmable control of local composition. PMID:26396254

  7. Ternary Fission Studies by Correlation Measurements with Ternary Particles

    NASA Astrophysics Data System (ADS)

    Mutterer, Manfred

    2011-10-01

    The rare ternary fission process has been studied mainly by inclusive measurements of the energy distributions and fractional yields of the light charged particles (LCPs) from fission, or by experiments on the angular and energy correlation between LCPs and fission fragments (FFs). The present contribution presents a brief overview of more elaborate correlation measurements that comprise the emission of neutrons and γ rays with LCPs and FFs, or the coincident registration of two LCPs. These measurements have permitted identification of new modes of particle-accompanied fission, such as the population of excited states in LCPs, the formation of neutron-unstable nuclei as short-lived intermediate LCPs, as well as the sequential decay of particle-unstable LCPs and quaternary fission. Furthermore, the neutron multiplicity numbers bar ν (A) and distributions of fragment masses A, measured for the ternary fission modes with various LCP isotopes, give a valuable hint of the role played by nuclear shell structure in the fission process near scission. Finally, two different hitherto unknown asymmetries in ternary α-particle emission with respect to the fission axis, called the TRI and ROT effect, were studied in fission reactions induced by polarised cold neutrons.

  8. Water-soluble ruthenium complexes bearing activity against protozoan parasites.

    PubMed

    Sarniguet, Cynthia; Toloza, Jeannette; Cipriani, Micaella; Lapier, Michel; Vieites, Marisol; Toledano-Magaña, Yanis; García-Ramos, Juan Carlos; Ruiz-Azuara, Lena; Moreno, Virtudes; Maya, Juan Diego; Azar, Claudio Olea; Gambino, Dinorah; Otero, Lucía

    2014-06-01

    Parasitic illnesses are major causes of human disease and misery worldwide. Among them, both amebiasis and Chagas disease, caused by the protozoan parasites, Entamoeba histolytica and Trypanosoma cruzi, are responsible for thousands of annual deaths. The lack of safe and effective chemotherapy and/or the appearance of current drug resistance make the development of novel pharmacological tools for their treatment relevant. In this sense, within the framework of the medicinal inorganic chemistry, metal-based drugs appear to be a good alternative to find a pharmacological answer to parasitic diseases. In this work, novel ruthenium complexes [RuCl2(HL)(HPTA)2]Cl2 with HL=bioactive 5-nitrofuryl containing thiosemicarbazones and PTA=1,3,5-triaza-7-phosphaadamantane have been synthesized and fully characterized. PTA was included as co-ligand in order to modulate complexes aqueous solubility. In fact, obtained complexes were water soluble. Their activity against T. cruzi and E. histolytica was evaluated in vitro. [RuCl2(HL4)(HPTA)2]Cl2 complex, with HL4=N-phenyl-5-nitrofuryl-thiosemicarbazone, was the most active compound against both parasites. In particular, it showed an excellent activity against E. histolytica (half maximal inhibitory concentration (IC50)=5.2 μM), even higher than that of the reference drug metronidazole. In addition, this complex turns out to be selective for E. histolytica (selectivity index (SI)>38). The potential mechanism of antiparasitic action of the obtained ruthenium complexes could involve oxidative stress for both parasites. Additionally, complexes could interact with DNA as second potential target by an intercalative-like mode. Obtained results could be considered a contribution in the search for metal compounds that could be active against multiple parasites. PMID:24740394

  9. CURRENT AND KINETIC HELICITY OF LONG-LIVED ACTIVITY COMPLEXES

    SciTech Connect

    Komm, Rudolf; Gosain, Sanjay

    2015-01-01

    We study long-lived activity complexes and their current helicity at the solar surface and their kinetic helicity below the surface. The current helicity has been determined from synoptic vector magnetograms from the NSO/SOLIS facility, and the kinetic helicity of subsurface flows has been determined with ring-diagram analysis applied to full-disk Dopplergrams from NSO/GONG and SDO/HMI. Current and kinetic helicity of activity complexes follow the hemispheric helicity rule with mainly positive values (78%; 78%, respectively, with a 95% confidence level of 31%) in the southern hemisphere and negative ones (80%; 93%, respectively, with a 95% confidence level of 22% and 14%, respectively) in the northern hemisphere. The locations with the dominant sign of kinetic helicity derived from Global Oscillation Network Group (GONG) and SDO/HMI data are more organized than those of the secondary sign even if they are not part of an activity complex, while locations with the secondary sign are more fragmented. This is the case for both hemispheres even for the northern one where it is not as obvious visually due to the large amount of magnetic activity present as compared to the southern hemisphere. The current helicity shows a similar behavior. The dominant sign of current helicity is the same as that of kinetic helicity for the majority of the activity complexes (83% with a 95% confidence level of 15%). During the 24 Carrington rotations analyzed here, there is at least one longitude in each hemisphere where activity complexes occur repeatedly throughout the epoch. These ''active'' longitudes are identifiable as locations of strong current and kinetic helicity of the same sign.

  10. Binuclear Rhodium(II) Complexes With Selective Antibacterial Activity.

    PubMed

    Bień, M; Lachowicz, T M; Rybka, A; Pruchnik, F P; Trynda, L

    1997-01-01

    Binuclear rhodium(II) complexes [Rh(2)Cl(2)(mu-OOCR)(2)(N-N)(2)] {R = H, Me; N-N = 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen)} and [Rh(2)(mu-OOCR)(2)(N-N)(2)(H(2)O)(2)](RCOO)(2) (R = Me, Et;) have been synthesized and their structure and properties have been studied by electronic, IR and (1)H NMR spectroscopy. Antibacterial activity of these complexes against Escherichia coli and Staphylococcus aureus has been investigated. The most active antibacterial agents against E. coli were [Rh(2)Cl(2)(mu-OOCR)(2)(N-N)(2)] and [Rh(2)(mu-OOCR)(2)(N-N)(2)(H(2)O)(2)](RCOO)(2) {R = H and Me} which were considerably more active than the appropriate nitrogen ligands. The complexes show low activity against S. aureus. The activity of the complexes [Rh(2)(OOCR)(2)(N-N)(2)(H(2)O)(2)](OOCR)(2) against E. coli decreases in the series: R=H congruent withCH(3)>C(2)H(5)>C(3)H(7) congruent withC(4)H(9). The reverse order was found in the case of S. aureus. PMID:18475773

  11. Models for the Binary Complex of Bacteriophage T4 Gp59 Helicase Loading Protein. GP32 Single-Stranded DNA-Binding Protein and Ternary Complex with Pseudo-Y Junction DNA

    SciTech Connect

    Hinerman, Jennifer M.; Dignam, J. David; Mueser, Timothy C.

    2012-04-05

    The bacteriophage T4 gp59 helicase assembly protein (gp59) is required for loading of gp41 replicative helicase onto DNA protected by gp32 single-stranded DNA-binding protein. The gp59 protein recognizes branched DNA structures found at replication and recombination sites. Binding of gp32 protein (full-length and deletion constructs) to gp59 protein measured by isothermal titration calorimetry demonstrates that the gp32 protein C-terminal A-domain is essential for protein-protein interaction in the absence of DNA. Sedimentation velocity experiments with gp59 protein and gp32ΔB protein (an N-terminal B-domain deletion) show that these proteins are monomers but form a 1:1 complex with a dissociation constant comparable with that determined by isothermal titration calorimetry. Small angle x-ray scattering (SAXS) studies indicate that the gp59 protein is a prolate monomer, consistent with the crystal structure and hydrodynamic properties determined from sedimentation velocity experiments. SAXS experiments also demonstrate that gp32ΔB protein is a prolate monomer with an elongated A-domain protruding from the core. Moreover, fitting structures of gp59 protein and the gp32 core into the SAXS-derived molecular envelope supports a model for the gp59 protein-gp32ΔB protein complex. Our earlier work demonstrated that gp59 protein attracts full-length gp32 protein to pseudo-Y junctions. A model of the gp59 protein-DNA complex, modified to accommodate new SAXS data for the binary complex together with mutational analysis of gp59 protein, is presented in the accompanying article (Dolezal, D., Jones, C. E., Lai, X., Brister, J. R., Mueser, T. C., Nossal, N. G., and Hinton, D. M. (2012) J. Biol. Chem. 287, 18596–18607).

  12. Equal area rule methods for ternary systems

    SciTech Connect

    Shyu, G.S.; Hanif, N.S.M.; Alvarado, J.F.J.; Hall, K.R.; Eubank, P.T.

    1995-12-01

    The phase equilibrium behavior of fluid mixtures is an important design consideration for both chemical processes and oil production. Eubank and Hall have recently shown the equal area rule (EAR) applies to the composition derivative of the Gibbs energy of a binary system at fixed pressure and temperature regardless of derivative continuity. A sufficient condition for equilibria, EAR is faster and simpler than either the familiar tangent-line method or the area method of Eubank et al. Here, the authors show that EAR can be extended to ternary systems exhibiting one, two, or three phases at equilibrium. A single directional vector is searched in composition space; at equilibrium, this vector is the familiar tie line. A sensitive criterion for equilibrium under EAR is equality of orthogonal derivatives such as ({partial_derivative}g/{partial_derivative}x{sub 1}){sub x{sub 2}P,T} at the end points ({alpha} and {beta}), where g {equivalent_to} ({Delta}{sub m}G/RT). Repeated use of the binary algorithm published in the first reference allows rapid, simple solution of ternary problems, even with hand-held calculations for cases where the background model is simple (e.g., activity coefficient models) and the derivative continuous.

  13. Comparison of Solar Active Region Complexity Andgeomagnetic Activity from 1996 TO 2014

    NASA Astrophysics Data System (ADS)

    Tanskanen, E. I.; Nikbakhsh, S.; Perez-Suarez, D.; Hackman, T.

    2015-12-01

    We have studied the influence of magnetic complexity of solar Active Regions (ARs)on geomagnetic activity from 1996 to 2014. Sunspots are visual indicators of ARswhere the solar magnetic field is disturbed. We have used International, American,Space Environment Service Center (SESC) and Space Weather Prediction Center(SWPC) sunspot numbers to examine ARs. Major manifestations of solar magneticactivity, such as flares and Coronal Mass Ejections (CMEs), are associated withARs. For this study we chose the Mount Wilson scheme. It classifies ARs in terms oftheir magnetic topology from the least complex (?) to the most complex one ( ?).Several cases have been found where the more complex structures produce strongerflares and CMEs than the less complex ones. We have a list of identified substormsavailable with different phases and their durations. This will be compared to ourmagnetic complexity data to analyse the effects of active region magnetic complexityto the magnetic activity on the vicinity of the Earth.

  14. Nucleation and interfacial adsorption in ternary systems.

    PubMed

    Philippe, T

    2015-03-01

    Nucleation is studied in incompressible ternary fluids by examining the topology of the overall landscape of the energy surface. Minimum free energy paths for nucleation (MFEPs) of a single nucleus in an infinite matrix are computed with the string method in the framework of the continuum theory of nucleation for the regular solution. Properties of the critical nucleus are compared with the predictions of the classical nucleation theory. MFEPs are found to exhibit complex nucleation pathways with non-monotonic variations of compositions in the interfacial region, specifically adsorption of a component. In the symmetric regular solution, the minority component is found to segregate at the interface during nucleation with a concomitant depletion of the nucleus core, resulting in unpredicted partition of the non-selective component. Despite increasing the gradient energy, such inhomogeneity in composition is shown to lower the nucleation barrier. PMID:25747088

  15. Efficient Management of Complex Striped Files in Active Storage

    SciTech Connect

    Piernas Canovas, Juan; Nieplocha, Jaroslaw

    2008-08-25

    Active Storage provides an opportunity for reducing the band- width requirements between the storage and compute elements of cur- rent supercomputing systems, and leveraging the processing power of the storage nodes used by some modern file systems. To achieve both objec- tives, Active Storage allows certain processing tasks to be performed directly on the storage nodes, near the data they manage. However, Active Storage must also support key requirements of scientific applications. In particular, Active Storage must be able to support striped files and files with complex formats (e.g., netCDF). In this paper, we describe how these important requirements can be addressed. The experimental results on a Lustre file system not only show that our proposal can re- duce the network traffic to near zero and scale the performance with the number of storage nodes, but also that it provides an efficient treatment of striped files and can manage files with complex data structures.

  16. Environmental layout complexity affects neural activity during navigation in humans.

    PubMed

    Slone, Edward; Burles, Ford; Iaria, Giuseppe

    2016-05-01

    Navigating large-scale surroundings is a fundamental ability. In humans, it is commonly assumed that navigational performance is affected by individual differences, such as age, sex, and cognitive strategies adopted for orientation. We recently showed that the layout of the environment itself also influences how well people are able to find their way within it, yet it remains unclear whether differences in environmental complexity are associated with changes in brain activity during navigation. We used functional magnetic resonance imaging to investigate how the brain responds to a change in environmental complexity by asking participants to perform a navigation task in two large-scale virtual environments that differed solely in interconnection density, a measure of complexity defined as the average number of directional choices at decision points. The results showed that navigation in the simpler, less interconnected environment was faster and more accurate relative to the complex environment, and such performance was associated with increased activity in a number of brain areas (i.e. precuneus, retrosplenial cortex, and hippocampus) known to be involved in mental imagery, navigation, and memory. These findings provide novel evidence that environmental complexity not only affects navigational behaviour, but also modulates activity in brain regions that are important for successful orientation and navigation. PMID:26990572

  17. Surface Segregation in Ternary Alloys

    NASA Technical Reports Server (NTRS)

    Good, Brian; Bozzolo, Guillermo H.; Abel, Phillip B.

    2000-01-01

    Surface segregation profiles of binary (Cu-Ni, Au-Ni, Cu-Au) and ternary (Cu-Au-Ni) alloys are determined via Monte Carlo-Metropolis computer simulations using the BFS method for alloys for the calculation of the energetics. The behavior of Cu or Au in Ni is contrasted with their behavior when both are present. The interaction between Cu and Au and its effect on the segregation profiles for Cu-Au-Ni alloys is discussed.

  18. Activation of the C-H bond by metal complexes

    NASA Astrophysics Data System (ADS)

    Shilov, Aleksandr E.; Shul'pin, Georgiy B.

    1990-09-01

    Reactions involving the cleavage of C-H bonds by metal complexes in saturated and aromatic hydrocarbons and also in other compounds are examined. Some of these processes occur with formation of a carbon-metal bond, whilst in others the interaction of the complexes with the hydrocarbon takes place without direct contact between the metal atom and the C-H bonds. Metal compounds are widely used as initiators of the liquid-phase oxidation of hydrocarbons at relatively low temperatures. There is a prospect of creating new technologies for the chemical processing of petroleum and gas hydrocarbons, whereby they can be converted into valuable products, for example, into alcohols, ketones, and carboxylic acids, on the basis of processes involving metal complexes. The study of the metal complex activation of the C-H bond also makes it possible to understand and model the metalloenzyme-catalysed hydrocarbon oxidation reactions in the living cell. The bibliography includes 340 references.

  19. C-H bond activation by f-block complexes.

    PubMed

    Arnold, Polly L; McMullon, Max W; Rieb, Julia; Kühn, Fritz E

    2015-01-01

    Most homogeneous catalysis relies on the design of metal complexes to trap and convert substrates or small molecules to value-added products. Organometallic lanthanide compounds first gave a tantalizing glimpse of their potential for catalytic C-H bond transformations with the selective cleavage of one C-H bond in methane by bis(permethylcyclopentadienyl)lanthanide methyl [(η(5) -C5 Me5 )2 Ln(CH3 )] complexes some 25 years ago. Since then, numerous metal complexes from across the periodic table have been shown to selectively activate hydrocarbon C-H bonds, but the challenges of closing catalytic cycles still remain; many f-block complexes show great potential in this important area of chemistry. PMID:25384554

  20. Synthesis, characterization and antioxidant activity copper-quercetin complex

    NASA Astrophysics Data System (ADS)

    Bukhari, S. Birjees; Memon, Shahabuddin; Mahroof-Tahir, M.; Bhanger, M. I.

    2009-01-01

    Quercetin (3,3',4',5,7-pentahydroxyflavone) one of the most abundant dietary flavonoids, has been investigated in the presence of Cu(II) in methanol. The spectroscopic studies (UV-vis, 1H NMR and IR) were useful to assess the relevant interaction of Quercetin with Cu(II) ions, the chelation sites and dependence of the complex structure from the metal/ligand ratio. A 1:2 (L:M) complex was indicated by Job's method of continuous variation, which was applied to ascertain the stoichiometric composition of the complex. The antioxidant activities of the compounds were evaluated by using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. The complexed flavonoid was much more effective free radical scavengers than the free flavonoids.

  1. Local Activity Principle:. the Cause of Complexity and Symmetry Breaking

    NASA Astrophysics Data System (ADS)

    Mainzer, Klaus

    2013-01-01

    The principle of local activity is precisely the missing concept to explain the emergence of complex patterns in a homogeneous medium. Leon O. Chua discovered and defined this principle in the theory of nonlinear electronic circuits in a mathematically rigorous way. The local principle can be generalized and proven at least for the class of nonlinear reaction-diffusion systems in physics, chemistry, biology and brain research. Recently, it was realized by memristors for nanoelectronic device applications in technical brains. In general, the emergence of complex patterns and structures is explained by symmetry breaking in homogeneous media. The principle of local activity is the cause of symmetry breaking in homogeneous media. We argue that the principle of local activity is really fundamental in science and can even be identified in quantum cosmology as symmetry breaking of local gauge symmetries generating the complexity of matter and forces in our universe. Finally, we consider applications in economic, financial, and social systems with the emergence of equilibrium states, symmetry breaking at critical points of phase transitions and risky acting at the edge of chaos. In any case, the driving causes of symmetry breaking and the emergence of complexity are locally active elements, cells, units, or agents.

  2. Immersion freezing of ice nucleating active protein complexes

    NASA Astrophysics Data System (ADS)

    Hartmann, S.; Augustin, S.; Clauss, T.; Voigtländer, J.; Niedermeier, D.; Wex, H.; Stratmann, F.

    2012-08-01

    Biological particles, e.g. bacteria and their Ice Nucleating Active (INA) protein complexes, might play an important role for the ice formation in atmospheric mixed-phase clouds. Therefore, the immersion freezing behavior of INA protein complexes generated from a SnomaxTM solution/suspension was investigated as function of temperature in a range of -5 °C to -38 °C at the Leipzig Aerosol Cloud Interaction Simulator (LACIS). The immersion freezing of droplets containing small numbers of INA protein complexes occurs in a temperature range of -7 °C and -10 °C. The experiments performed in the lower temperature range, where all droplets freeze which contain at least one INA protein complex, are used to determine the average number of INA protein complexes present, assuming that the INA protein complexes are Poisson distributed over the droplet ensemble. Knowing the average number of INA protein complexes, the heterogeneous ice nucleation rate and rate coefficient of a single INA protein complex is determined by using the newly-developed CHESS model (stoCHastic model of idEntical poiSSon distributed ice nuclei). Therefore, we assume the ice nucleation process to be of stochastic nature, and a parameterization of the INA protein complex's nucleation rate. Analyzing the results of immersion freezing experiments from literature (SnomaxTM and Pseudomonas syringae bacteria), to results gained in this study, demonstrates that first, a similar temperature dependence of the heterogeneous ice nucleation rate for a single INA protein complex was found in all experiments, second, the shift of the ice fraction curves to higher temperatures can be explained consistently by a higher average number of INA protein complexes being present in the droplet ensemble, and finally the heterogeneous ice nucleation rate of one single INA protein complex might be also applicable for intact Pseudomonas syringae bacteria cells. The results obtained in this study allow a new perspective on the

  3. 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.

  4. Similar Biological Activities of Two Isostructural Ruthenium and Osmium Complexes

    SciTech Connect

    Maksimoska,J.; Williams, D.; Atilla-Gokcumen, G.; Smalley, K.; Carroll, P.; Webster, R.; Filippakopoulos, P.; Knapp, S.; Herlyn, M.; Meggers, E.

    2008-01-01

    In this study, we probe and verify the concept of designing unreactive bioactive metal complexes, in which the metal possesses a purely structural function, by investigating the consequences of replacing ruthenium in a bioactive half-sandwich kinase inhibitor scaffold by its heavier congener osmium. The two isostructural complexes are compared with respect to their anticancer properties in 1205?Lu melanoma cells, activation of the Wnt signaling pathway, IC50 values against the protein kinases GSK-3? and Pim-1, and binding modes to the protein kinase Pim-1 by protein crystallography. It was found that the two congeners display almost indistinguishable biological activities, which can be explained by their nearly identical three-dimensional structures and their identical mode of action as protein kinase inhibitors. This is a unique example in which the replacement of a metal in an anticancer scaffold by its heavier homologue does not alter its biological activity.

  5. Superoxide scavenging activity of pirfenidone-iron complex

    SciTech Connect

    Mitani, Yoshihiro; Sato, Keizo Muramoto, Yosuke; Karakawa, Tomohiro; Kitamado, Masataka; Iwanaga, Tatsuya; Nabeshima, Tetsuji; Maruyama, Kumiko; Nakagawa, Kazuko; Ishida, Kazuhiko; Sasamoto, Kazumi

    2008-07-18

    Pirfenidone (PFD) is focused on a new anti-fibrotic drug, which can minimize lung fibrosis etc. We evaluated the superoxide (O{sub 2}{sup {center_dot}}{sup -}) scavenging activities of PFD and the PFD-iron complex by electron spin resonance (ESR) spectroscopy, luminol-dependent chemiluminescence assay, and cytochrome c reduction assay. Firstly, we confirmed that the PFD-iron complex was formed by mixing iron chloride with threefold molar PFD, and the complex was stable in distillated water and ethanol. Secondary, the PFD-iron complex reduced the amount of O{sub 2}{sup {center_dot}}{sup -} produced by xanthine oxidase/hypoxanthine without inhibiting the enzyme activity. Thirdly, it also reduced the amount of O{sub 2}{sup {center_dot}}{sup -} released from phorbor ester-stimulated human neutrophils. PFD alone showed few such effects. These results suggest the possibility that the O{sub 2}{sup {center_dot}}{sup -} scavenging effect of the PFD-iron complex contributes to the anti-fibrotic action of PFD used for treating idiopathic pulmonary fibrosis.

  6. Metal biosorption equilibria in a ternary system

    SciTech Connect

    Chong, K.H.; Volesky, B.

    1996-03-20

    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 and with conclusions postulated from the three possible binary subsystems.

  7. Genome-wide activities of Polycomb complexes control pervasive transcription.

    PubMed

    Lee, Hun-Goo; Kahn, Tatyana G; Simcox, Amanda; Schwartz, Yuri B; Pirrotta, Vincenzo

    2015-08-01

    Polycomb group (PcG) complexes PRC1 and PRC2 are well known for silencing specific developmental genes. PRC2 is a methyltransferase targeting histone H3K27 and producing H3K27me3, essential for stable silencing. Less well known but quantitatively much more important is the genome-wide role of PRC2 that dimethylates ∼70% of total H3K27. We show that H3K27me2 occurs in inverse proportion to transcriptional activity in most non-PcG target genes and intergenic regions and is governed by opposing roaming activities of PRC2 and complexes containing the H3K27 demethylase UTX. Surprisingly, loss of H3K27me2 results in global transcriptional derepression proportionally greatest in silent or weakly transcribed intergenic and genic regions and accompanied by an increase of H3K27ac and H3K4me1. H3K27me2 therefore sets a threshold that prevents random, unscheduled transcription all over the genome and even limits the activity of highly transcribed genes. PRC1-type complexes also have global roles. Unexpectedly, we find a pervasive distribution of histone H2A ubiquitylated at lysine 118 (H2AK118ub) outside of canonical PcG target regions, dependent on the RING/Sce subunit of PRC1-type complexes. We show, however, that H2AK118ub does not mediate the global PRC2 activity or the global repression and is predominantly produced by a new complex involving L(3)73Ah, a homolog of mammalian PCGF3. PMID:25986499

  8. A Fractal Dimension Survey of Active Region Complexity

    NASA Technical Reports Server (NTRS)

    McAteer, R. T. James; Gallagher, Peter; Ireland, Jack

    2005-01-01

    A new approach to quantifying the magnetic complexity of active regions using a fractal dimension measure is presented. This fully-automated approach uses full disc MDI magnetograms of active regions from a large data set (2742 days of the SoHO mission; 9342 active regions) to compare the calculated fractal dimension to both Mount Wilson classification and flare rate. The main Mount Wilson classes exhibit no distinct fractal dimension distribution, suggesting a self-similar nature of all active regions. Solar flare productivity exhibits an increase in both the frequency and GOES X-ray magnitude of flares from regions with higher fractal dimensions. Specifically a lower threshold fractal dimension of 1.2 and 1.25 exists as a necessary, but not sufficient, requirement for an active region to produce M- and X-class flares respectively .

  9. Geometric complexity identifies platelet activation in familial hypercholesterolemic patients.

    PubMed

    Bianciardi, Giorgio; Aglianò, Margherita; Volpi, Nila; Stefanutti, Claudia

    2015-06-01

    Familial hypercholesterolemia (FH), a genetic disease, is associated with a severe incidence of athero-thrombotic events, related, also, to platelet hyperreactivity. A plethora of methods have been proposed to identify those activated circulating platelets, none of these has proved really effective. We need efficient methods to identify the circulating platelet status in order to follow the patients after therapeutic procedures. We propose the use of computerized fractal analysis for an objective characterization of the complexity of circulating platelet shapes observed by means of transmission electron microscopy in order to characterize the in vivo hyperactivated platelets of familial hypercholesterolemic patients, distinguishing them from the in vivo resting platelets of healthy individuals. Platelet boundaries were extracted by means of automatically image analysis. Geometric complexity (fractal dimension, D) by box counting was automatically calculated. The platelet boundary observed by electron microscopy is fractal, the shape of the circulating platelets is more complex in FH (n = 6) than healthy subjects (n = 5, P < 0.01), with 100% correct classification in selected individuals. In vitro activated platelets from healthy subjects show an analogous increase of D. The observed high D in the platelet boundary in FH originates from the in vivo platelet activation. Computerized fractal analysis of platelet shape observed by transmission electron microscopy can provide accurate, quantitative data to study platelet activation in familial hypercholesterolemia and after administration of drugs or other therapeutic procedures. PMID:25877374

  10. The antimicrobial and antibiofilm activities of copper(II) complexes.

    PubMed

    Beeton, Michael L; Aldrich-Wright, Janice R; Bolhuis, Albert

    2014-11-01

    Biofilm-related bacterial infections pose a significant problem, as they are generally more tolerant to antibiotics and the immune system. Development of novel compounds with antibiofilm activity is therefore paramount. In this study we have analysed metal complexes of the general structure [M(IL)(AL)](2+) (where IL represents functionalised 1,10-phenanthrolines and AL represents 1S,2S- or 1R,2R-diaminocyclohexane) and [Cu(IL)3](2+). Antimicrobial activity was tested on a number of bacterial strains, showing that copper(II) compounds were active against both Gram-positive and Gram-negative bacteria, albeit that activity was generally higher for the former. The antibiofilm activity was then determined against a clinical isolate of meticillin-resistant Staphylococcus aureus (MRSA). Strikingly, the copper complexes tested showed significant activity against biofilms, and were better in the removal of biofilms than vancomycin, an antibiotic that is currently used in the treatment of MRSA infections. PMID:25124857

  11. Active control technique of fractional-order chaotic complex systems

    NASA Astrophysics Data System (ADS)

    Mahmoud, Gamal M.; Ahmed, Mansour E.; Abed-Elhameed, Tarek M.

    2016-06-01

    Several kinds of synchronization of fractional-order chaotic complex systems are challenging research topics of current interest since they appear in many applications in applied sciences. Our main goal in this paper is to introduce the definition of modified projective combination-combination synchronization (MPCCS) of some fractional-order chaotic complex systems. We show that our systems are chaotic by calculating their Lyapunov exponents. The fractional Lyapunov dimension of the chaotic solutions of these systems is computed. A scheme is introduced to calculate MPCCS of four different (or identical) chaotic complex systems using the active control technique. Special cases of this type, which are projective and anti C-C synchronization, are discussed. Some figures are plotted to show that MPCCS is achieved and its errors approach zero.

  12. Preparation of meloxicam-β-cyclodextrin-polyethylene glycol 6000 ternary system: characterization, in vitro and in vivo bioavailability.

    PubMed

    Radia, Ourezki; Rogalska, Ewa; Moulay-Hassane, Guermouche

    2012-01-01

    Ternary complexes of meloxicam (ML), a poorly water-soluble anti-inflammatory drug, with β-cyclodextrin (βCD) and polyethylene glycol (PEG) 6000 were prepared from an equimolar (ML-βCD) and 10% of PEG. Characterization of the ternary complex was carried out by differential scanning calorimetry and X-ray diffractometry. The solubility of ML increased as a function of increasing the concentration of βCD and PEG 6000. Ternary system increased significantly ML solubility in water. Ternary complexes improved drug release compared with ML and ML-βCD. The oral bioavailability of ML-βCD-PEG was investigated by administration to rat and compared with ML and ML-βCD. The results confirmed that the oral bioavailability of ML was significantly improved by complexation with βCD in the presence of PEG. PMID:21428700

  13. Comparison of catalytic activities for photocatalytic and sonocatalytic degradation of organic dye in the presence of ternary Fe3O4/ZnO/CuO magnetic heteregenous nanocatalyst

    NASA Astrophysics Data System (ADS)

    Taufik, Ardiansyah; Saleh, Rosari

    2016-04-01

    The Fe3O4/ZnO/CuO nanocatalyst with various CuO loading were synthesized by sol-gel method and were characterized by powder X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV-Vis spectroscopy, and vibrating sample magnetometry. The findings demonstrate that all samples exhibit ferromagnetic behavior at room temperatureand containa well-crystalline ternary oxide nanocatalyst. Methylene blue was taken as the model of organic dye to evaluate its photocatalytic and sonocatalytic degradation in the presence of Fe3O4/ZnO/CuO nanocatalyst. The observed degradation activity indicate that the order of degradation of methylene blue issonocatalysis> photocatalysis. Fe3O4/ZnO/CuO nanocatalyst with the lowest CuO loading exhibit the highest rate of degradation of methylene blue during the sono- and photocatalytic processes. The experimental data shows that holes are the predominant oxidative species involved in the sono- and photodegradation of methylene blue.

  14. Geometric complexity is increased in in vitro activated platelets.

    PubMed

    Bianciardi, Giorgio

    2015-06-01

    This article investigates the use of computerized fractal analysis for objective characterization of the complexity of platelets in vitro stimulated by low level thrombin (0.02 U mL(-1) ), collected from healthy individuals and observed by means of transmission electron microscopy. Platelet boundaries were extracted by means of automatically image analysis. Local fractal dimension was evaluated by the box-counting technique (measure of geometric complexity of the platelet outline). The results showed that the platelet boundary is fractal when observed by transmission electron microscopy and that, after an in vitro platelet activation test, the shape of platelets present increased geometric complexity in comparison to the no stimulated platelets (P < 0.001), with 100% correct classification. Computerized fractal analysis of platelet shape by transmission electron microscopy can provide accurate, quantitative, data to study platelet activation. The results may play important roles in the evaluation of the platelets status in pathological conditions, like as atherosclerosis and diabetes mellitus, where in in vivo activated platelets have been described. PMID:25808036

  15. Distinct TFIID complexes mediate the effect of different transcriptional activators.

    PubMed Central

    Brou, C; Chaudhary, S; Davidson, I; Lutz, Y; Wu, J; Egly, J M; Tora, L; Chambon, P

    1993-01-01

    Multiple chromatographically separable complexes containing the TATA binding protein (TBP), which exhibit different functional properties, exist in HeLa cells. At least three distinct subpopulations of such complexes can be functionally defined as TFIID since they function with RNA polymerase II. Using a partially reconstituted HeLa cell in vitro transcription system and immunoprecipitation with a monoclonal antibody directed against TBP, we show that stimulation of transcription by the chimeric activators GAL-VP16, GAL-TEF-1 and GAL-ER(EF) requires the presence of factors which are tightly associated with these TFIID complexes. Moreover, the activity of GAL-TEF-1 appears to be mediated by at least two chromatographically distinct populations of TFIID. The factor(s) associated with one of these populations is also required for the activity of GAL-ER (EF) and GAL-VP16, while the factor(s) associated with the other population functions selectively with GAL-TEF-1. These two TFIID populations are composed of both common and unique TBP associated factors (TAFs). Images PMID:8440239

  16. Interaction energy in pairs of phthalazinium dibenzoylmethylid (PDBM)-protic solvent molecules estimated in the limits of the cell ternary solution model, by spectral means

    NASA Astrophysics Data System (ADS)

    Nicoleta, Melniciuc-Puica; Mihaela, Avadanei; Maria, Caprosu; Dana Ortansa, Dorohoi

    2012-10-01

    The dipolar compound Phthalazinium-dibenzoylmethylid (PDBM) was used as spectrally active molecule in order to analyze the molecular interactions in ternary solutions containing at least one protic solvent. In PDBM + protic solvent (1) + aprotic solvent (2) ternary solutions, PDBM can be involved both in universal and specific interactions reflected in solvatochromic effects. The protic solvent (or the solvent with the higher electric permittivity) was considered as being active from the interactions point of view. The content of the first solvation sphere of the studied ylid has been established on the basis of the statistical cell model of ternary solutions. The active solvent molecules are dominant in the first solvation sphere of the PDBM molecules. The difference between the interaction energies in the PDBM-active solvent (1) and PDBM-inactive solvent (2) molecular pairs has been determined for three binary solvents water + ethanol (W + E), propionic acid + chloroform (PA + C) and octanol + 1,2 dichloroethane (O + DCE). The hydrogen bond formation energy of the PDBM-protic solvent complex has been estimated in the binary solvents PA + C and O + DCE containing one protic (PA and O, respectively) and one aprotic solvent with close electro-optical parameters refractive index and electric permittivity of the components.

  17. Mixed ternary heterojunction solar cell

    DOEpatents

    Chen, Wen S.; Stewart, John M.

    1992-08-25

    A thin film heterojunction solar cell and a method of making it has a p-type layer of mixed ternary I-III-VI.sub.2 semiconductor material in contact with an n-type layer of mixed binary II-VI semiconductor material. The p-type semiconductor material includes a low resistivity copper-rich region adjacent the back metal contact of the cell and a composition gradient providing a minority carrier mirror that improves the photovoltaic performance of the cell. The p-type semiconductor material preferably is CuInGaSe.sub.2 or CuIn(SSe).sub.2.

  18. Reconfigurable ternary optical processor based on row operation unit

    NASA Astrophysics Data System (ADS)

    Kai, SONG; LiPing, YAN

    2015-09-01

    In order to eliminate the difference between the data bits and the pixel bits of the processors in the logic operation of Ternary Optical Computer (TOC), and to make the reconfiguration of the processors more convenient and efficient, while extending the research ideas of TOC, the paper presents a new typical optical component, which is row operation unit (ROU). The features, circuit implementations, and commands for the reconfiguration of ROU are also discussed in detail. On this basis, the reconfigurable ternary optical processor (RTOP) was designed and achieved, which reduces the complexity of the processor management software. Finally, the experiments of reconfigurable ROU are performed, which shows that the principles of RTOP are correct, and all 81 commands for the reconfiguration are effective. Each of the two-input, tri-valued logic operations with thousands of data bits can be concurrently achieved in RTOP.

  19. Activities of topoisomerase I in its complex with SRSF1.

    PubMed

    Ishikawa, Takao; Krzysko, Krystiana A; Kowalska-Loth, Barbara; Skrajna, Aleksandra M; Czubaty, Alicja; Girstun, Agnieszka; Cieplak, Maja K; Lesyng, Bogdan; Staron, Krzysztof

    2012-02-28

    Human DNA topoisomerase I (topo I) catalyzes DNA relaxation and phosphorylates SRSF1. Whereas the structure of topo I complexed with DNA has been resolved, the structure of topo I in the complex with SRSF1 and structural determinants of topo I activities in this complex are not known. The main obstacle to resolving the structure is a contribution of unfolded domains of topo I and SRSF1 in formation of the complex. To overcome this difficulty, we employed a three-step strategy: identifying the interaction regions, modeling the complex, and validating the model with biochemical methods. The binding sites in both topo I and SRSF1 are localized in the structured regions as well as in the unfolded domains. One observes cooperation between the binding sites in topo I but not in SRSF1. Our results indicate two features of the unfolded RS domain of SRSF1 containing phosphorylated residues that are critical for the kinase activity of topo I: its spatial arrangement relative to topo I and the organization of its sequence. The efficiency of phosphorylation of SRSF1 depends on the length and flexibility of the spacer between the two RRM domains that uniquely determine an arrangement of the RS domain relative to topo I. The spacer also influences inhibition of DNA nicking, a prerequisite for DNA relaxation. To be phosphorylated, the RS domain has to include a short sequence recognized by topo I. A lack of this sequence in the mutants of SRSF1 or its spatial inaccessibility in SRSF9 makes them inadequate as topo I/kinase substrates. PMID:22320324

  20. Metal-dithiocarbamate complexes: chemistry and biological activity.

    PubMed

    Hogarth, Graeme

    2012-10-01

    Dithiocarbamates are highly versatile mono-anionic chelating ligands which form stable complexes with all the transition elements and also the majority of main group, lanthanide and actinide elements. They are easily prepared from primary or secondary amines and depending upon the nature of the cation can show good solubility in water or organic solvents. They are related to the thiuram disulfides by a one-electron redox process (followed by dimerisation via sulfur-sulfur bond formation) which is easily carried out upon addition of iodide or ferric salts. Dithiocarbamates are lipophilic and generally bind to metals in a symmetrical chelate fashion but examples of other coordination modes are known, the monodentate and anisobidentate modes being most prevalent. They are planar sterically non-demanding ligands which can be electronically tuned by judicious choice of substituents. They stabilize metals in a wide range of oxidation states, this being attributed to the existence of soft dithiocarbamate and hard thioureide resonance forms, the latter formally resulting from delocalization of the nitrogen lone pair onto the sulfurs, and consequently their complexes tend to have a rich electrochemistry. Tetraethyl thiuramdisulfide (disulfiram or antabuse) has been used as a drug since the 1950s but it is only recently that dithiocarbamate complexes have been explored within the medicinal domain. Over the past two decades anti-cancer activity has been noted for gold and copper complexes, technetium and copper complexes have been used in PET-imaging, dithiocarbamates have been used to treat acute cadmium poisoning and copper complexes also have been investigated as SOD inhibitors. PMID:22931592

  1. Phase transformations in ternary monotectic aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gröbner, Joachim; Schmid-Fetzer, Rainer

    2005-09-01

    Monotectic aluminum alloys are of interest for the development of new alloys for technological applications such as self-lubricating bearings. In contrast to the well-known binary phase diagrams, many of the ternary systems are not well established. Moreover, in a ternary monotectic alloy one may encounter the four-phase equilibrium L‧+L″+solid1+solid2, whereas in a binary system only a three-phase equilibrium L‧+L″+solid1 is possible. This opens a window for generating entirely new monotectic microstructures. The basis for such developments is the knowledge of the ternary phase diagrams and the conditions under which such four-phase reactions or different extensions of the binary monotectic reactions may form. This work presents a systematic classification of monotectic ternary aluminum alloys, illustrated by real systems. The study employs thermodynamic calculations of the ternary phase diagrams.

  2. Synthesis, structure, DNA binding and DNA cleavage activity of oxovanadium(IV) N-salicylidene-S-methyldithiocarbazate complexes of phenanthroline bases.

    PubMed

    Sasmal, Pijus K; Patra, Ashis K; Chakravarty, Akhil R

    2008-07-01

    Ternary oxovanadium(IV) complexes [VO(salmdtc)(B)] (1-3), where salmdtc is dianionic N-salicylidene-S-methyldithiocarbazate and B is N,N-donor phenanthroline bases like 1,10-phenanthroline (phen, 1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 2) and dipyrido[3,2-a:2',3'-c]phenazine (dppz, 3), are prepared, characterized and their DNA binding and DNA cleavage activity studied. Complex 3 is structurally characterized by single-crystal X-ray crystallography. The molecular structure shows the presence of a vanadyl group in six-coordinate VN(3)O(2)S coordination geometry. The S-methyldithiocarbazate Schiff base acts as a tridentate NSO-donor ligand in a meridional binding mode. The N,N-donor heterocyclic base displays a chelating mode of binding with an N-donor site trans to the vanadyl oxo-group. The complexes show a d-d band in the range of 675-707 nm in DMF. They exhibit an irreversible oxidative cyclic voltammetric response near 0.9 V due to the V(V)/V(IV) couple and a quasi-reversible reductive V(IV)/V(III) redox couple near -1.0 V vs. SCE in DMF-0.1M TBAP. The complexes show good binding propensity to calf thymus DNA giving binding constant values in the range of 7.4 x 10(4)-2.3 x 10(5)M(-1). The thermal denaturation and viscosity binding data suggest DNA surface and/or groove binding nature of the complexes. The complexes show poor chemical nuclease activity in dark in the presence of 3-mercaptopropionic acid (MPA) or hydrogen peroxide. The dpq and dppz complexes show efficient DNA cleavage activity in UV-A light of 365 nm via a type-II mechanistic pathway involving formation of singlet oxygen ((1)O(2)) as the reactive species. PMID:18279964

  3. Integrin activation and focal complex formation in cardiac hypertrophy

    NASA Technical Reports Server (NTRS)

    Laser, M.; Willey, C. D.; Jiang, W.; Cooper, G. 4th; Menick, D. R.; Zile, M. R.; Kuppuswamy, D.

    2000-01-01

    Cardiac hypertrophy is characterized by both remodeling of the extracellular matrix (ECM) and hypertrophic growth of the cardiocytes. Here we show increased expression and cytoskeletal association of the ECM proteins fibronectin and vitronectin in pressure-overloaded feline myocardium. These changes are accompanied by cytoskeletal binding and phosphorylation of focal adhesion kinase (FAK) at Tyr-397 and Tyr-925, c-Src at Tyr-416, recruitment of the adapter proteins p130(Cas), Shc, and Nck, and activation of the extracellular-regulated kinases ERK1/2. A synthetic peptide containing the Arg-Gly-Asp (RGD) motif of fibronectin and vitronectin was used to stimulate adult feline cardiomyocytes cultured on laminin or within a type-I collagen matrix. Whereas cardiocytes under both conditions showed RGD-stimulated ERK1/2 activation, only collagen-embedded cells exhibited cytoskeletal assembly of FAK, c-Src, Nck, and Shc. In RGD-stimulated collagen-embedded cells, FAK was phosphorylated only at Tyr-397 and c-Src association occurred without Tyr-416 phosphorylation and p130(Cas) association. Therefore, c-Src activation is not required for its cytoskeletal binding but may be important for additional phosphorylation of FAK. Overall, our study suggests that multiple signaling pathways originate in pressure-overloaded heart following integrin engagement with ECM proteins, including focal complex formation and ERK1/2 activation, and many of these pathways can be activated in cardiomyocytes via RGD-stimulated integrin activation.

  4. GT-CATS: Tracking Operator Activities in Complex Systems

    NASA Technical Reports Server (NTRS)

    Callantine, Todd J.; Mitchell, Christine M.; Palmer, Everett A.

    1999-01-01

    Human operators of complex dynamic systems can experience difficulties supervising advanced control automation. One remedy is to develop intelligent aiding systems that can provide operators with context-sensitive advice and reminders. The research reported herein proposes, implements, and evaluates a methodology for activity tracking, a form of intent inferencing that can supply the knowledge required for an intelligent aid by constructing and maintaining a representation of operator activities in real time. The methodology was implemented in the Georgia Tech Crew Activity Tracking System (GT-CATS), which predicts and interprets the actions performed by Boeing 757/767 pilots navigating using autopilot flight modes. This report first describes research on intent inferencing and complex modes of automation. It then provides a detailed description of the GT-CATS methodology, knowledge structures, and processing scheme. The results of an experimental evaluation using airline pilots are given. The results show that GT-CATS was effective in predicting and interpreting pilot actions in real time.

  5. Bioreducible polyether-based pDNA ternary polyplexes: Balancing particle stability and transfection efficiency

    PubMed Central

    Lai, Tsz Chung; Kataoka, Kazunori; Kwon, Glen S.

    2016-01-01

    Polyplex particles formed with plasmid DNA (pDNA) and Pluronic P85-block-poly{N-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} (P85-b-P[Asp(DET)]) demonstrated highly effective transfection ability compared to PEG-based block cationomer, PEG-b-P[Asp(DET)]. Ternary polyplexes comprising PEG-b-P[Asp(DET)], poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)-b-P[Asp(DET)] (P(EPE)-b-P[Asp(DET)]) used as an analog of P85-b-P[Asp(DET)], and pDNA were prepared in this work aiming at maintaining adequate transfection efficiency while solving the stability issues of the P85-b-P[Asp(DET)] polyplexes. Furthermore, a bioreducible P(EPE)-SS-P[Asp(DET)] possessing a redox potential-sensitive disulfide linkage between the P(EPE) polymer and the cationic block was used as a substitute for P(EPE)-b-P[Asp(DET)] during ternary complex formation to investigate whether the trans-fection ability of the ternary polyplex system could be enhanced by triggered release of P(EPE) polymers from the polyplexes. The ternary complexes showed significant improvement in terms of stability against salt-induced aggregation compared to binary complexes, although the gene delivery ability dropped with the amount of PEG-b-P[Asp(DET)] used for complexation. By manipulating the difference in redox potential between the extracellular and intracellular environments, the reducible ternary complexes achieved higher transfection compared to the non-reducible polyplexes; moreover, the reducible poly-plexes exhibited comparable stability to the non-reducible ones. These results suggest that reducible ternary complexes could provide satisfactory transfection efficiency without comprising the colloidal stability of the particles. PMID:22000077

  6. Immersion freezing of ice nucleation active protein complexes

    NASA Astrophysics Data System (ADS)

    Hartmann, S.; Augustin, S.; Clauss, T.; Wex, H.; Šantl-Temkiv, T.; Voigtländer, J.; Niedermeier, D.; Stratmann, F.

    2013-06-01

    Utilising the Leipzig Aerosol Cloud Interaction Simulator (LACIS), the immersion freezing behaviour of droplet ensembles containing monodisperse particles, generated from a Snomax™ solution/suspension, was investigated. Thereto ice fractions were measured in the temperature range between -5 °C to -38 °C. Snomax™ is an industrial product applied for artificial snow production and contains Pseudomonas syringae} bacteria which have long been used as model organism for atmospheric relevant ice nucleation active (INA) bacteria. The ice nucleation activity of such bacteria is controlled by INA protein complexes in their outer membrane. In our experiments, ice fractions increased steeply in the temperature range from about -6 °C to about -10 °C and then levelled off at ice fractions smaller than one. The plateau implies that not all examined droplets contained an INA protein complex. Assuming the INA protein complexes to be Poisson distributed over the investigated droplet populations, we developed the CHESS model (stoCHastic modEl of similar and poiSSon distributed ice nuclei) which allows for the calculation of ice fractions as function of temperature and time for a given nucleation rate. Matching calculated and measured ice fractions, we determined and parameterised the nucleation rate of INA protein complexes exhibiting class III ice nucleation behaviour. Utilising the CHESS model, together with the determined nucleation rate, we compared predictions from the model to experimental data from the literature and found good agreement. We found that (a) the heterogeneous ice nucleation rate expression quantifying the ice nucleation behaviour of the INA protein complex is capable of describing the ice nucleation behaviour observed in various experiments for both, Snomax™ and P. syringae bacteria, (b) the ice nucleation rate, and its temperature dependence, seem to be very similar regardless of whether the INA protein complexes inducing ice nucleation are attached

  7. Active Printed Materials for Complex Self-Evolving Deformations

    PubMed Central

    Raviv, Dan; Zhao, Wei; McKnelly, Carrie; Papadopoulou, Athina; Kadambi, Achuta; Shi, Boxin; Hirsch, Shai; Dikovsky, Daniel; Zyracki, Michael; Olguin, Carlos; Raskar, Ramesh; Tibbits, Skylar

    2014-01-01

    We propose a new design of complex self-evolving structures that vary over time due to environmental interaction. In conventional 3D printing systems, materials are meant to be stable rather than active and fabricated models are designed and printed as static objects. Here, we introduce a novel approach for simulating and fabricating self-evolving structures that transform into a predetermined shape, changing property and function after fabrication. The new locally coordinated bending primitives combine into a single system, allowing for a global deformation which can stretch, fold and bend given environmental stimulus. PMID:25522053

  8. Active printed materials for complex self-evolving deformations.

    PubMed

    Raviv, Dan; Zhao, Wei; McKnelly, Carrie; Papadopoulou, Athina; Kadambi, Achuta; Shi, Boxin; Hirsch, Shai; Dikovsky, Daniel; Zyracki, Michael; Olguin, Carlos; Raskar, Ramesh; Tibbits, Skylar

    2014-01-01

    We propose a new design of complex self-evolving structures that vary over time due to environmental interaction. In conventional 3D printing systems, materials are meant to be stable rather than active and fabricated models are designed and printed as static objects. Here, we introduce a novel approach for simulating and fabricating self-evolving structures that transform into a predetermined shape, changing property and function after fabrication. The new locally coordinated bending primitives combine into a single system, allowing for a global deformation which can stretch, fold and bend given environmental stimulus. PMID:25522053

  9. Esterase activity of BSA-ZnO nanoparticle complex

    NASA Astrophysics Data System (ADS)

    Bhogale, A.; Nair, A.; Patel, N.; Miotello, A.; Kothari, D. C.

    2014-04-01

    The effect of Zinc Oxide Nanoparticles (ZnO NPs) on functional properties of Bovine Serum Albumin (BSA) protein was studied. ZnO NPs were synthesized with average size of ˜7.5 nm as obtained from TEM analysis. The catalytic conversion of p-nitrophenylacetate (PNPA) to p-nitrophenol in the presence of BSA attached with ZnO NPs was examined by UV-Vis spectroscopy at room temperature. The result suggests that esterase activity of BSA is significantly enhanced (6 times) due to the ground state BSA-ZnO complex formation.

  10. High activity of carbon nanotubes supported binary and ternary Pd-based catalysts for methanol, ethanol and formic acid electro-oxidation

    NASA Astrophysics Data System (ADS)

    Zhu, Fuchun; Ma, Guanshui; Bai, Zhongchao; Hang, Ruiqiang; Tang, Bin; Zhang, Zhonghua; Wang, Xiaoguang

    2013-11-01

    In this study, we have synthesized a series of multi-walled carbon nanotubes supported Pd, PdCu(molar ratio 1:1), PdSn(1:1) and PdCuSn(1:1:1) catalysts by chemical reduction with NaBH4 as a reducing agent. These catalysts are characterized using X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry and chronoamperometry. During the potential cycling activation, it is found that the additive Cu is prone to suffer leaching while the dissolution of Sn rarely occurs. Electrochemical measurements demonstrate that, the co-alloying of Pd with Cu and Sn can trigger the best catalytic activity enhancement as compared with the binary PdCu/CNTs, PdSn/CNTs and mono-component Pd/CNTs catalysts. The PdCuSn/CNTs reveals the most excellent activities toward methanol, ethanol and formic acid electro-oxidation and the corresponding mass activity can attain to 395.94, 872.70 and 534.83 mA mg-1 Pd, respectively. The possible promotion effect of additive Sn or/and Cu on the electrocatalytic activity improvement is also analyzed.

  11. Supramolecular coordination and antimicrobial activities of constructed mixed ligand complexes

    NASA Astrophysics Data System (ADS)

    El-Sonbati, A. Z.; Diab, M. A.; El-Bindary, A. A.; Abou-Dobara, M. I.; Seyam, H. A.

    2013-03-01

    A novel series of copper(II) and palladium(II) with 4-derivatives benzaldehyde pyrazolone (Ln) were synthesized. The mixed ligand complexes were prepared by using 1,10-phenanthroline (Phen) as second ligand. The structure of these complexes was identified and confirm by elemental analysis, molar conductivity, UV-Vis, IR and 1H NMR spectroscopy and magnetic moment measurements as well as thermal analysis. The ligand behaves as a neutral bidentate ligand through ON donor sites. ESR spectra show the simultaneous presence of a planar trans and a nearly planar cis isomers in the 1:2 ratio for all N,O complexes [Cu(Ln)2]Cl2ṡ2H2O. Schiff bases (Ln) were tested against bacterial species; namely two Gram positive bacteria (Staphylococcus aureus and Bacillus cereus) and two Gram negative bacteria (Escherichia coli and Klebsiella pneumoniae) and fungal species (Aspergillus niger, Fusarium oxysporium, Penicillium italicum and Alternaria alternata). The tested compounds have antibacterial activity against S. aureus, B. cereus and K. pneumoniae.

  12. Development and application of high strength ternary boride base cermets

    SciTech Connect

    Takagi, Ken-ichi . E-mail: u4381@toyokohan.co.jp

    2006-09-15

    Reaction boronizing sintering is a novel strategy to form a ternary boride coexisting with a metal matrix in a cermet during liquid phase sintering. This new sintering technique has successfully developed world first ternary boride base cermets with excellent mechanical properties such as Mo{sub 2}FeB{sub 2}, Mo{sub 2}NiB{sub 2} and WCoB base ones. In these cermets Mo{sub 2}FeB{sub 2} and Mo{sub 2}NiB{sub 2} base ones consist of a tetragonal M {sub 3}B{sub 2} (M: metal)-type complex boride as a hard phase and a transition metal base matrix. The cermets have already been applied to wear resistant applications such as injection molding machine parts, can making tools, and hot copper extruding dies, etc. This paper focuses on the characteristics, effects of the additional elements on the mechanical properties and structure, and practical applications of the ternary boride base cermets. - Graphical abstract: TRS and hardness of Ni-5B-51Mo-17.5Cr and Ni-5B-51Mo-12.5Cr-5V-xMn mass% cermets as functions of Mn content (Fig. 17)

  13. Multifractality as a Measure of Complexity in Solar Flare Activity

    NASA Astrophysics Data System (ADS)

    Sen, Asok K.

    2007-03-01

    In this paper we use the notion of multifractality to describe the complexity in H α flare activity during the solar cycles 21, 22, and 23. Both northern and southern hemisphere flare indices are analyzed. Multifractal behavior of the flare activity is characterized by calculating the singularity spectrum of the daily flare index time series in terms of the Hölder exponent. The broadness of the singularity spectrum gives a measure of the degree of multifractality or complexity in the flare index data. The broader the spectrum, the richer and more complex is the structure with a higher degree of multifractality. Using this broadness measure, complexity in the flare index data is compared between the northern and southern hemispheres in each of the three cycles, and among the three cycles in each of the two hemispheres. Other parameters of the singularity spectrum can also provide information about the fractal properties of the flare index data. For instance, an asymmetry to the left or right in the singularity spectrum indicates a dominance of high or low fractal exponents, respectively, reflecting a relative abundance of large or small fluctuations in the total energy emitted by the flares. Our results reveal that in the even (22nd) cycle the singularity spectra are very similar for the northern and southern hemispheres, whereas in the odd cycles (21st and 23rd) they differ significantly. In particular, we find that in cycle 21, the northern hemisphere flare index data have higher complexity than its southern counterpart, with an opposite pattern prevailing in cycle 23. Furthermore, small-scale fluctuations in the flare index time series are predominant in the northern hemisphere in the 21st cycle and are predominant in the southern hemisphere in the 23rd cycle. Based on these findings one might suggest that, from cycle to cycle, there exists a smooth switching between the northern and southern hemispheres in the multifractality of the flaring process. This new

  14. Activation of signalling by the activin receptor complex.

    PubMed Central

    Attisano, L; Wrana, J L; Montalvo, E; Massagué, J

    1996-01-01

    Activin exerts its effects by simultaneously binding to two types of p rotein serine/threonine kinase receptors, each type existing in various isoforms. Using the ActR-IB and ActR-IIB receptor isoforms, we have investigated the mechanism of activin receptor activation. ActR-IIB are phosphoproteins with demonstrable affinity for each other. However, activin addition strongly promotes an interaction between these two proteins. Activin binds directly to ActR-IIB, and this complex associates with ActR-IB, which does not bind ligand on its own. In the resulting complex, ActR-IB becomes hyperphosphorylated, and this requires the kinase activity of ActR-IIB. Mutation of conserved serines and threonines in the GS domain, a region just upstream of the kinase domain in ActR-IB, abrogates both phosphorylation and signal propagation, suggesting that this domain contains phosphorylation sites required for signalling. ActR-IB activation can be mimicked by mutation of Thr-206 to aspartic acid, which yields a construct, ActR-IB(T206D), that signals in the absence of ligand. Furthermore, the signalling activity of this mutant construct is undisturbed by overexpression of a dominant negative kinase-defective ActR-IIB construct, indicating that ActR-IB(T206D) can signal independently of ActR-IIB. The evidence suggests that ActR-IIB acts as a primary activin receptor and ActR-IB acts as a downstream transducer of activin signals. PMID:8622651

  15. Performance Assessment Assistance Activities in the DOE Complex - 12325

    SciTech Connect

    Seitz, Roger R.; Phifer, Mark A.; Letourneau, Martin J.

    2012-07-01

    The United States Department of Energy Office of Environmental Management (DOE-EM) has established a Performance Assessment Community of Practice (PA CoP) to foster the sharing of information among performance assessment (PA) and risk assessment practitioners, regulators and oversight personnel. The general intent is to contribute to continuous improvement in the consistency, technical adequacy and quality of implementation of PAs and risk assessments around the DOE Complex. The PA CoP activities have involved commercial disposal facilities and international participants to provide a global perspective. The PA CoP has also sponsored annual technical exchanges as a means to foster improved communication and to share lessons learned from on-going modelling activities. The PA CoP encourages activities to provide programmatic and technical assistance in the form of sharing experience and lessons learned with practitioners during the development of PAs and risk assessments. This assistance complements DOE-EM reviews through the Low-Level Waste Disposal Facility Federal Review Group (LFRG) that are conducted after modelling efforts are completed. Such up-front assistance is providing additional value in terms of improving consistency and sharing of information. There has been a substantial increase in the amount of assistance being provided. The assistance has been well received by practitioners and regulators that have been involved. The paper highlights assistance and sharing of information that has been conducted in the last two years to support activities underway in support of proposed disposal facilities at Paducah, Portsmouth, and the Idaho National Laboratory and tank closure at Hanford. DOE-EM established the PA CoP to help improve the consistency and quality of implementation of modelling activities around the DOE Complex. The PA CoP has sponsored annual technical exchanges as a means to foster improved communication and to share lessons learned from ongoing

  16. TERNARY ALLOY-CONTAINING PLUTONIUM

    DOEpatents

    Waber, J.T.

    1960-02-23

    Ternary alloys of uranium and plutonium containing as the third element either molybdenum or zirconium are reported. Such alloys are particularly useful as reactor fuels in fast breeder reactors. The alloy contains from 2 to 25 at.% of molybdenum or zirconium, the balance being a combination of uranium and plutonium in the ratio of from 1 to 9 atoms of uranlum for each atom of plutonium. These alloys are prepared by melting the constituent elements, treating them at an elevated temperature for homogenization, and cooling them to room temperature, the rate of cooling varying with the oomposition and the desired phase structure. The preferred embodiment contains 12 to 25 at.% of molybdenum and is treated by quenching to obtain a body centered cubic crystal structure. The most important advantage of these alloys over prior binary alloys of both plutonium and uranium is the lack of cracking during casting and their ready machinability.

  17. All-optical symmetric ternary logic gate

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay

    2010-09-01

    Symmetric ternary number (radix=3) has three logical states (1¯, 0, 1). It is very much useful in carry free arithmetical operation. Beside this, the logical operation using this type of number system is also effective in high speed computation and communication in multi-valued logic. In this literature all-optical circuits for three basic symmetrical ternary logical operations (inversion, MIN and MAX) are proposed and described. Numerical simulation verifies the theoretical model. In this present scheme the different ternary logical states are represented by different polarized state of light. Terahertz optical asymmetric demultiplexer (TOAD) based interferometric switch has been used categorically in this manuscript.

  18. Applications of ternary systems in specific cosmetic formulations.

    PubMed

    Comelles, F; Megias, V; Sánchez, J; Parra, J L; Coll, J; Balaguer, F; Pelejero, C

    1989-02-01

    Synopsis The study of ternary systems leads to the understanding of the physico-chemical aspect and allows the contribution of the different components to a cosmetic formulation to be developed. The present investigation was centred in the zone of transparent get belonging to a previously studied ternary system containing a broad variety of different structural compositions. The possibility of including an active sunscreen as well as the ability to increase the water content of the gel was studied. The microscopical study of the compositions with polarized light allowed us to assign the corresponding different structures. A correlation between these structures and their physico-chemical properties, with special emphasis to rheology, has been established. PMID:19456930

  19. Lunar granites with unique ternary feldspars

    NASA Technical Reports Server (NTRS)

    Ryder, G.; Stoeser, D. B.; Marvin, U. B.; Bower, J. F.

    1975-01-01

    An unusually high concentration of granitic fragments, with textures ranging from holocrystalline to glassy, occurs throughout Boulder 1, a complex breccia of highland rocks from Apollo 17, Station 2. Among the minerals included in the granites are enigmatic K-Ca-rich feldspars that fall in the forbidden region of the ternary diagram. The great variability in chemistry and texture is probably the result of impact degradation and melting of a granitic source-rock. Studies of the breccia matrix suggest that this original granitic source-rock may have contained more pyroxenes and phosphates than most of the present clasts contain. Petrographic observations on Apollo 15 KREEP basalts indicate that granitic liquids may be produced by differentiation without immiscibility, and the association of the granites with KREEP-rich fragments in the boulder suggests that the granites represent a residual liquid from the plutonic fractional crystallization of a KREEP-rich magma. Boulder 1 is unique among Apollo 17 samples in its silica-KREEP-rich composition. We conclude that the boulder represents a source-rock unlike the bedrock of South Massif.

  20. Mechanical and water barrier properties of agar/κ-carrageenan/konjac glucomannan ternary blend biohydrogel films.

    PubMed

    Rhim, Jong-Whan; Wang, Long-Feng

    2013-07-01

    Multicomponent hydrogel films composed of agar, κ-carrageenan, konjac glucomannan powder, and nanoclay (Cloisite(®) 30B) were prepared and their mechanical and water barrier properties such as water vapor permeability (WVP), water contact angle (CA), water solubility (WS), water uptake ratio (WUR), water vapor uptake ratio (WVUR) were determined. Mechanical, water vapor barrier, and water resistance properties of the ternary blend film exhibited middle range of individual component films, however, they increased significantly after formation of nanocomposite with the clay. Especially, the water holding capacity of the ternary blend biopolymer films increased tremendously, from 800% to 1681% of WUR for agar and κ-carrageenan films up to 5118% and 5488% of WUR for the ternary blend and ternary blend nanocomposite films, respectively. Water vapor adsorption behavior of films was also tested by water vapor adsorption kinetics and water vapor adsorption isotherms test. Preliminary test result for fresh spinach packaging revealed that the ternary blend biohydrogel films had a high potential for the use as an antifogging film for packaging highly respiring agricultural produce. In addition, the ternary blend nanocomposite film showed an antimicrobial activity against Gram-positive bacteria, Listeria monocytogenes. PMID:23688456

  1. Mitogen activated protein kinase at the nuclear pore complex

    PubMed Central

    Faustino, Randolph S; Maddaford, Thane G; Pierce, Grant N

    2011-01-01

    Abstract Mitogen activated protein (MAP) kinases control eukaryotic proliferation, and import of kinases into the nucleus through the nuclear pore complex (NPC) can influence gene expression to affect cellular growth, cell viability and homeostatic function. The NPC is a critical regulatory checkpoint for nucleocytoplasmic traffic that regulates gene expression and cell growth, and MAP kinases may be physically associated with the NPC to modulate transport. In the present study, highly enriched NPC fractions were isolated and investigated for associated kinases and/or activity. Endogenous kinase activity was identified within the NPC fraction, which phosphorylated a 30 kD nuclear pore protein. Phosphomodification of this nucleoporin, here termed Nup30, was inhibited by apigenin and PD-98059, two MAP kinase antagonists as well as with SB-202190, a pharmacological blocker of p38. Furthermore, high throughput profiling of enriched NPCs revealed constitutive presence of all members of the MAP kinase family, extracellular regulated kinases (ERK), p38 and Jun N-terminal kinase. The NPC thus contains a spectrum of associated MAP kinases that suggests an intimate role for ERK and p38 in regulation of nuclear pore function. PMID:20497490

  2. Ternary Kv4.2 channels recapitulate voltage-dependent inactivation kinetics of A-type K+ channels in cerebellar granule neurons

    PubMed Central

    Amarillo, Yimy; De Santiago-Castillo, Jose A; Dougherty, Kevin; Maffie, Jonathon; Kwon, Elaine; Covarrubias, Manuel; Rudy, Bernardo

    2008-01-01

    Kv4 channels mediate most of the somatodendritic subthreshold operating A-type current (ISA) in neurons. This current plays essential roles in the regulation of spike timing, repetitive firing, dendritic integration and plasticity. Neuronal Kv4 channels are thought to be ternary complexes of Kv4 pore-forming subunits and two types of accessory proteins, Kv channel interacting proteins (KChIPs) and the dipeptidyl-peptidase-like proteins (DPPLs) DPPX (DPP6) and DPP10. In heterologous cells, ternary Kv4 channels exhibit inactivation that slows down with increasing depolarization. Here, we compared the voltage dependence of the inactivation rate of channels expressed in heterologous mammalian cells by Kv4.2 proteins with that of channels containing Kv4.2 and KChIP1, Kv4.2 and DPPX-S, or Kv4.2, KChIP1 and DPPX-S, and found that the relation between inactivation rate and membrane potential is distinct for these four conditions. Moreover, recordings from native neurons showed that the inactivation kinetics of the ISA in cerebellar granule neurons has voltage dependence that is remarkably similar to that of ternary Kv4 channels containing KChIP1 and DPPX-S proteins in heterologous cells. The fact that this complex and unique behaviour (among A-type K+ currents) is observed in both the native current and the current expressed in heterologous cells by the ternary complex containing Kv4, DPPX and KChIP proteins supports the hypothesis that somatically recorded native Kv4 channels in neurons include both types of accessory protein. Furthermore, quantitative global kinetic modelling showed that preferential closed-state inactivation and a weakly voltage-dependent opening step can explain the slowing of the inactivation rate with increasing depolarization. Therefore, it is likely that preferential closed-state inactivation is the physiological mechanism that regulates the activity of both ternary Kv4 channel complexes and native ISA-mediating channels. PMID:18276729

  3. Varying modulation of HIV-1 LTR activity by Baf complexes.

    PubMed

    Van Duyne, Rachel; Guendel, Irene; Narayanan, Aarthi; Gregg, Edward; Shafagati, Nazly; Tyagi, Mudit; Easley, Rebecca; Klase, Zachary; Nekhai, Sergei; Kehn-Hall, Kylene; Kashanchi, Fatah

    2011-08-19

    The human immunodeficiency virus type 1 (HIV-1) long terminal repeat is present on both ends of the integrated viral genome and contains regulatory elements needed for transcriptional initiation and elongation. Post-integration, a highly ordered chromatin structure consisting of at least five nucleosomes, is found at the 5' long terminal repeat, the location and modification state of which control the state of active viral replication as well as silencing of the latent HIV-1 provirus. In this context, the chromatin remodeling field rapidly emerges as having a critical role in the control of viral gene expression. In the current study, we focused on unique Baf subunits that are common to the most highly recognized of chromatin remodeling proteins, the SWI/SNF (switching-defective-sucrose non-fermenting) complexes. We find that at least two Baf proteins, Baf53 and Baf170, are highly regulated in HIV-1-infected cells. Previously, studies have shown that the depletion of Baf53 in uninfected cells leads to the expansion of chromosomal territories and the decompaction of the chromatin. Baf53, in the presence of HIV-1 infection, co-elutes off of a chromatographic column as a different-sized complex when compared to uninfected cells and appears to be predominantly phosphorylated. The innate function of Baf53-containing complexes appears to be transcriptionally suppressive, in that knocking down Baf53 increases viral gene expression from cells both transiently and chronically infected with HIV-1. Additionally, cdk9/cyclin T in the presence of Tat is able to phosphorylate Baf53 in vitro, implying that this posttranslationally modified form relieves the suppressive effect and allows for viral transcription to proceed. PMID:21699904

  4. Ternary Copper(II) Complexes With Indomethacin, a Potent Non-Steroidal Antiinflammatory Drug. Crystal Structure of Bis (Dimethylformamide)-Tetrakis[1-(4-Chlorobenzoyl)-5-Methoxy-2-Methyl-1-H-Indole-3-Acetato]Dicopper(II). Antiinflammatory Properties and Prevention of Gastrointestinal Side Effects by Nanocapsules

    PubMed Central

    Guessous, Fadila; Daran, Jean-Claude; Viossat, Bernard; Morgant, Georges; Labouze, Xavier; Leroy, Anne Laure; Roch-Arveiller, Monique

    1998-01-01

    Two ternary copper(ll) complexes of indomethacin [1-(4-chlorobenzoyl)-5-methoxy-2- methyl-1-H-indole-3-acetic acid] called hereafter lndo, were prepared and characterized by single crystal X-ray diffraction. The first complex Cu2(Indo)4(DMF)2 I crystallizes in space group P-1 (a = 10.829(2), b = 13.379(2), c = 16.491(3) Å; α = 105.58(2), β = 101.06(2), γ = 106.96(2)°; V= 2104.6(6) Å3, Z= 1). The title molecule is a centrosymmetric binuclear complex, with Cu atoms bridged by the carboxylate moieties of four indomethacinate ligands. The four nearest O atoms around each Cu atom form a square planar arrangement with the square pyramidal coordination completed by the O atom of N,N′-dimethylformamide. Daily administration for seven days of 1 mg/kg of indomethacin, I and I encapsulated into liposomes induces a weak inflammation of rat gastrointestinal tract. I was less inflammatory than indomethacin but the better protection was brought by encapsulation of the compound. This might be of interest in sustained therapies of chronic inflammatory diseases. PMID:18475870

  5. Anticancer Activity of Metal Complexes: Involvement of Redox Processes

    PubMed Central

    Jungwirth, Ute; Kowol, Christian R.; Keppler, Bernhard K.; Hartinger, Christian G.; Berger, Walter; Heffeter, Petra

    2012-01-01

    Cells require tight regulation of the intracellular redox balance and consequently of reactive oxygen species for proper redox signaling and maintenance of metal (e.g., of iron and copper) homeostasis. In several diseases, including cancer, this balance is disturbed. Therefore, anticancer drugs targeting the redox systems, for example, glutathione and thioredoxin, have entered focus of interest. Anticancer metal complexes (platinum, gold, arsenic, ruthenium, rhodium, copper, vanadium, cobalt, manganese, gadolinium, and molybdenum) have been shown to strongly interact with or even disturb cellular redox homeostasis. In this context, especially the hypothesis of “activation by reduction” as well as the “hard and soft acids and bases” theory with respect to coordination of metal ions to cellular ligands represent important concepts to understand the molecular modes of action of anticancer metal drugs. The aim of this review is to highlight specific interactions of metal-based anticancer drugs with the cellular redox homeostasis and to explain this behavior by considering chemical properties of the respective anticancer metal complexes currently either in (pre)clinical development or in daily clinical routine in oncology. PMID:21275772

  6. Natural lecithin promotes neural network complexity and activity.

    PubMed

    Latifi, Shahrzad; Tamayol, Ali; Habibey, Rouhollah; Sabzevari, Reza; Kahn, Cyril; Geny, David; Eftekharpour, Eftekhar; Annabi, Nasim; Blau, Axel; Linder, Michel; Arab-Tehrany, Elmira

    2016-01-01

    Phospholipids in the brain cell membranes contain different polyunsaturated fatty acids (PUFAs), which are critical to nervous system function and structure. In particular, brain function critically depends on the uptake of the so-called "essential" fatty acids such as omega-3 (n-3) and omega-6 (n-6) PUFAs that cannot be readily synthesized by the human body. We extracted natural lecithin rich in various PUFAs from a marine source and transformed it into nanoliposomes. These nanoliposomes increased neurite outgrowth, network complexity and neural activity of cortical rat neurons in vitro. We also observed an upregulation of synapsin I (SYN1), which supports the positive role of lecithin in synaptogenesis, synaptic development and maturation. These findings suggest that lecithin nanoliposomes enhance neuronal development, which may have an impact on devising new lecithin delivery strategies for therapeutic applications. PMID:27228907

  7. Natural lecithin promotes neural network complexity and activity

    PubMed Central

    Latifi, Shahrzad; Tamayol, Ali; Habibey, Rouhollah; Sabzevari, Reza; Kahn, Cyril; Geny, David; Eftekharpour, Eftekhar; Annabi, Nasim; Blau, Axel; Linder, Michel; Arab-Tehrany, Elmira

    2016-01-01

    Phospholipids in the brain cell membranes contain different polyunsaturated fatty acids (PUFAs), which are critical to nervous system function and structure. In particular, brain function critically depends on the uptake of the so-called “essential” fatty acids such as omega-3 (n-3) and omega-6 (n-6) PUFAs that cannot be readily synthesized by the human body. We extracted natural lecithin rich in various PUFAs from a marine source and transformed it into nanoliposomes. These nanoliposomes increased neurite outgrowth, network complexity and neural activity of cortical rat neurons in vitro. We also observed an upregulation of synapsin I (SYN1), which supports the positive role of lecithin in synaptogenesis, synaptic development and maturation. These findings suggest that lecithin nanoliposomes enhance neuronal development, which may have an impact on devising new lecithin delivery strategies for therapeutic applications. PMID:27228907

  8. Sphingosine Facilitates SNARE Complex Assembly and Activates Synaptic Vesicle Exocytosis

    PubMed Central

    Darios, Frédéric; Wasser, Catherine; Shakirzyanova, Anastasia; Giniatullin, Artur; Goodman, Kerry; Munoz-Bravo, Jose L.; Raingo, Jesica; Jorgačevski, Jernej; Kreft, Marko; Zorec, Robert; Rosa, Juliana M.; Gandia, Luis; Gutiérrez, Luis M.; Binz, Thomas; Giniatullin, Rashid; Kavalali, Ege T.; Davletov, Bazbek

    2009-01-01

    Summary Synaptic vesicles loaded with neurotransmitters fuse with the plasma membrane to release their content into the extracellular space, thereby allowing neuronal communication. The membrane fusion process is mediated by a conserved set of SNARE proteins: vesicular synaptobrevin and plasma membrane syntaxin and SNAP-25. Recent data suggest that the fusion process may be subject to regulation by local lipid metabolism. Here, we have performed a screen of lipid compounds to identify positive regulators of vesicular synaptobrevin. We show that sphingosine, a releasable backbone of sphingolipids, activates synaptobrevin in synaptic vesicles to form the SNARE complex implicated in membrane fusion. Consistent with the role of synaptobrevin in vesicle fusion, sphingosine upregulated exocytosis in isolated nerve terminals, neuromuscular junctions, neuroendocrine cells and hippocampal neurons, but not in neurons obtained from synaptobrevin-2 knockout mice. Further mechanistic insights suggest that sphingosine acts on the synaptobrevin/phospholipid interface, defining a novel function for this important lipid regulator. PMID:19524527

  9. Dinitrogen activation upon reduction of a triiron(II) complex.

    PubMed

    Lee, Yousoon; Sloane, Forrest T; Blondin, Geneviève; Abboud, Khalil A; García-Serres, Ricardo; Murray, Leslie J

    2015-01-26

    Reaction of a trinuclear iron(II) complex, Fe3 Br3 L (1), with KC8 under N2 leads to dinitrogen activation products (2) from which Fe3 (NH)3 L (2-1; L is a cyclophane bridged by three β-diketiminate arms) was characterized by X-ray crystallography. (1) H NMR spectra of the protonolysis product of 2 synthesized under (14) N2 and (15) N2 confirm atmospheric N2 reduction, and ammonia is detected by the indophenol assay (yield ∼30 %). IR and Mössbauer spectroscopy, and elemental analysis on 2 and 2-1 as well as the tri(amido)triiron(II) 3 and tri(methoxo)triiron 4 congeners support our assignment of the reduction product as containing protonated N-atom bridges. PMID:25504859

  10. 75 FR 77047 - Statement on Sound Practices Concerning Elevated Risk Complex Structured Finance Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-10

    ... Finance Activities AGENCY: Office of Thrift Supervision (OTS), Treasury. ACTION: Notice and request for.... Title of Proposal: Statement on Sound Practices Concerning Elevated Risk Complex Structured Finance... Elevated Risk Complex Structured Finance Activities describes the types of internal controls and...

  11. Highly active carbon supported ternary PdSnPtx (x=0.1-0.7) catalysts for ethanol electro-oxidation in alkaline and acid media.

    PubMed

    Wang, Xiaoguang; Zhu, Fuchun; He, Yongwei; Wang, Mei; Zhang, Zhonghua; Ma, Zizai; Li, Ruixue

    2016-04-15

    A series of trimetallic PdSnPtx (x=0.1-0.7)/C catalysts with varied Pt content have been synthesized by co-reduction method using NaBH4 as a reducing agent. These catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and chronoamperometry (CA). The electrochemical results show that, after adding a minor amount of Pt dopant, the resultant PdSnPtx/C demonstrated more superior catalytic performance toward ethanol oxidation as compared with that of mono-/bi-metallic Pd/C or PdSn/C in alkaline solution and the PdSnPt0.2/C with optimal molar ratio reached the best. In acid solution, the PdSnPt0.2/C also depicted a superior catalytic activity relative to the commercial Pt/C catalyst. The possible enhanced synergistic effect between Pd, Sn/Sn(O) and Pt in an alloyed state should be responsible for the as-revealed superior ethanol electro-oxidation performance based upon the beneficial electronic effect and bi-functional mechanism. It implies the trimetallic PdSnPt0.2/C with a low Pt content has a promising prospect as anodic electrocatalyst in fields of alkali- and acid-type direct ethanol fuel cells. PMID:26851453

  12. Activating and Elucidating Metabolism of Complex Sugars in Yarrowia lipolytica.

    PubMed

    Ryu, Seunghyun; Hipp, Julie; Trinh, Cong T

    2016-02-01

    The oleaginous yeast Yarrowia lipolytica is an industrially important host for production of organic acids, oleochemicals, lipids, and proteins with broad biotechnological applications. Albeit known for decades, the unique native metabolism of Y. lipolytica for using complex fermentable sugars, which are abundant in lignocellulosic biomass, is poorly understood. In this study, we activated and elucidated the native sugar metabolism in Y. lipolytica for cell growth on xylose and cellobiose as well as their mixtures with glucose through comprehensive metabolic and transcriptomic analyses. We identified 7 putative glucose-specific transporters, 16 putative xylose-specific transporters, and 4 putative cellobiose-specific transporters that are transcriptionally upregulated for growth on respective single sugars. Y. lipolytica is capable of using xylose as a carbon source, but xylose dehydrogenase is the key bottleneck of xylose assimilation and is transcriptionally repressed by glucose. Y. lipolytica has a set of 5 extracellular and 6 intracellular β-glucosidases and is capable of assimilating cellobiose via extra- and intracellular mechanisms, the latter being dominant for growth on cellobiose as a sole carbon source. Strikingly, Y. lipolytica exhibited enhanced sugar utilization for growth in mixed sugars, with strong carbon catabolite activation for growth on the mixture of xylose and cellobiose and with mild carbon catabolite repression of glucose on xylose and cellobiose. The results of this study shed light on fundamental understanding of the complex native sugar metabolism of Y. lipolytica and will help guide inverse metabolic engineering of Y. lipolytica for enhanced conversion of biomass-derived fermentable sugars to chemicals and fuels. PMID:26682853

  13. Activating and Elucidating Metabolism of Complex Sugars in Yarrowia lipolytica

    PubMed Central

    Ryu, Seunghyun; Hipp, Julie

    2015-01-01

    The oleaginous yeast Yarrowia lipolytica is an industrially important host for production of organic acids, oleochemicals, lipids, and proteins with broad biotechnological applications. Albeit known for decades, the unique native metabolism of Y. lipolytica for using complex fermentable sugars, which are abundant in lignocellulosic biomass, is poorly understood. In this study, we activated and elucidated the native sugar metabolism in Y. lipolytica for cell growth on xylose and cellobiose as well as their mixtures with glucose through comprehensive metabolic and transcriptomic analyses. We identified 7 putative glucose-specific transporters, 16 putative xylose-specific transporters, and 4 putative cellobiose-specific transporters that are transcriptionally upregulated for growth on respective single sugars. Y. lipolytica is capable of using xylose as a carbon source, but xylose dehydrogenase is the key bottleneck of xylose assimilation and is transcriptionally repressed by glucose. Y. lipolytica has a set of 5 extracellular and 6 intracellular β-glucosidases and is capable of assimilating cellobiose via extra- and intracellular mechanisms, the latter being dominant for growth on cellobiose as a sole carbon source. Strikingly, Y. lipolytica exhibited enhanced sugar utilization for growth in mixed sugars, with strong carbon catabolite activation for growth on the mixture of xylose and cellobiose and with mild carbon catabolite repression of glucose on xylose and cellobiose. The results of this study shed light on fundamental understanding of the complex native sugar metabolism of Y. lipolytica and will help guide inverse metabolic engineering of Y. lipolytica for enhanced conversion of biomass-derived fermentable sugars to chemicals and fuels. PMID:26682853

  14. Antiherpetic activity of the traditionally used complex essential oil Olbas.

    PubMed

    Heidary Navid, M; Reichling, J; Schnitzler, P

    2013-08-01

    Essential oils of medicinal plants are increasingly of interest as novel drugs for antiherpetic agents, since herpes simplex virus (HSV) might develop resistance to commonly used antiviral drugs. The antiviral effect of Olbas, a traditionally used complex essential oil, and of cajuput oil, a major constitutent of Olbas, against HSV type 1 was examined. The antiviral activity of these essential oils was tested in vitro on monkey kidney cells using a plaque reduction assay. The 50% inhibitory concentration (IC50) of Olbas and cajuput oil for herpes simplex virus plaque formation was determined at 1.8 microg/ml and 7.5 microg/ml, respectively. At noncytotoxic concentrations of these oils, plaque formation was significantly reduced by 99% for Olbas and 66% for cajuput oil. The selectivity index of 150 for Olbas against herpes simplex virus was superior to a rather low selectivity index for cajuput oil. The mode of antiviral action of these essential oils was assessed by time-on-addition assays. Herpesvirus was significantly inhibited by pretreatment with Olbas essential oil prior to infection of cells. These results indicate that Olbas affected the virus before adsorption, but not after penetration into the host cell, thus Olbas exerted a direct antiviral effect on HSV. A clearly time-dependent antiviral activity for Olbas and cajuput oil could be demonstrated. Considering the lipophilic nature of the Olbas complex essential oil mixture, which enables it to penetrate the skin, and a high selectivity index, Olbas might be suitable for topical treatment of herpetic infections. PMID:24020128

  15. Patterns of Neural Activity in Networks with Complex Connectivity

    NASA Astrophysics Data System (ADS)

    Solla, Sara A.

    2008-03-01

    An understanding of emergent dynamics on complex networks requires investigating the interplay between the intrinsic dynamics of the node elements and the connectivity of the network in which they are embedded. In order to address some of these questions in a specific scenario of relevance to the dynamical states of neural ensembles, we have studied the collective behavior of excitable model neurons in a network with small-world topology. The small-world network has local lattice order, but includes a number of randomly placed connections that may provide connectivity shortcuts. This topology bears a schematic resemblance to the connectivity of the cerebral cortex, in which neurons are most strongly coupled to nearby cells within fifty to a hundred micrometers, but also make projections to cells millimeters away. We find that the dynamics of this small-world network of excitable neurons depend mostly on both the density of shortcuts and the delay associated with neuronal projections. In the regime of low shortcut density, the system exhibits persistent activity in the form of propagating waves, which annihilate upon collision and are spawned anew via the re-injection of activity through shortcut connections. As the density of shortcuts reaches a critical value, the system undergoes a transition to failure. The critical shortcut density results from matching the time associated with a recurrent path through the network to an intrinsic recovery time of the individual neurons. Furthermore, if the delay associated with neuronal interactions is sufficiently long, activity reemerges above the critical density of shortcuts. The activity in this regime exhibits long, chaotic transients composed of noisy, large-amplitude population bursts.

  16. PERFORMANCE ASSESSMENT ASSISTANCE ACTIVITIES IN THE DOE COMPLEX

    SciTech Connect

    Seitz, R.

    2012-01-23

    The United States Department of Energy Office of Environmental Management (DOE-EM) has established a Performance Assessment Community of Practice (PA CoP) to foster the sharing of information among performance assessment (PA) and risk assessment practitioners, regulators and oversight personnel. The general intent is to contribute to continuous improvement in the consistency, technical adequacy and quality of implementation of PAs and risk assessments around the DOE Complex. The PA CoP activities have involved commercial disposal facilities and international participants to provide a global perspective. The PA CoP has also sponsored annual technical exchanges as a means to foster improved communication and to share lessons learned from on-going modelling activities. The PA CoP encourages activities to provide programmatic and technical assistance in the form of sharing experience and lessons learned with practitioners during the development of PAs and risk assessments. This assistance complements DOE-EM reviews through the Low-Level Waste Disposal Facility Federal Review Group (LFRG) that are conducted after modelling efforts are completed. Such up-front assistance is providing additional value in terms of improving consistency and sharing of information. There has been a substantial increase in the amount of assistance being provided. The assistance has been well received by practitioners and regulators that have been involved. The paper highlights assistance and sharing of information that has been conducted in the last two years to support activities underway in support of proposed disposal facilities at Paducah, Portsmouth, and the Idaho National Laboratory and tank closure at Hanford.

  17. Electroless ternary NiCeP coatings: Preparation and characterisation

    NASA Astrophysics Data System (ADS)

    Balaraju, J. N.; Chembath, Manju

    2012-10-01

    Electroless ternary NiCeP deposits were prepared from alkaline citrate bath containing nickel sulphate, cerium chloride and sodium hypophosphite. Concentration of rare earth cerium was varied from 1 to 2 g/L to obtain ternary deposits containing variable Ce and P contents. The influence of cerium on the deposit properties was analysed. The deposit exhibited a maximum cerium content of 6.2 ± 0.1 wt.% when the cerium chloride concentration was 2 g/L. The result of the Pd stability test showed that the stability of the bath was reduced due to Ce salt addition. The microhardness measurements made on both as-plated and heat treated samples exhibited a peak hardness of 1006 ± 11 VHN for cerium concentration of 1.5 g/L. The concept of kinetic strength analysis was proved to be applicable only for binary and not for ternary alloys due to multistep deposition mechanism with different kinetic energies. X-ray diffraction (XRD) patterns of as-plated and heat treated samples revealed peaks corresponding to Ni (1 1 1) and nickel phosphide (Ni3P). Higher amount of Ce incorporation in NiP matrix increased the crystallisation temperature of the deposit which could be due to the suppression of nickel crystallisation prior to Ni3P compound formation and thus increasing the activation energy for the formation of stable phases. Surface compositional analysis using X-ray photoelectron spectroscopy (XPS) carried out on as-plated NiCeP-2 deposit showed a prominent peak of P existing in +1 oxidation state as higher alkalinity favoured hypophosphite deposition in the ternary alloy coating. It was observed that the co-deposition of Ce in NiP matrix improved the continuous salt spray exposure for 168 h.

  18. Density functional for ternary non-additive hard sphere mixtures.

    PubMed

    Schmidt, Matthias

    2011-10-19

    Based on fundamental measure theory, a Helmholtz free energy density functional for three-component mixtures of hard spheres with general, non-additive interaction distances is constructed. The functional constitutes a generalization of the previously given theory for binary non-additive mixtures. The diagrammatic structure of the spatial integrals in both functionals is of star-like (or tree-like) topology. The ternary diagrams possess a higher degree of complexity than the binary diagrams. Results for partial pair correlation functions, obtained via the Ornstein-Zernike route from the second functional derivatives of the excess free energy functional, agree well with Monte Carlo simulation data. PMID:21946780

  19. Transition metal complexes of neocryptolepine analogues. Part I: Synthesis, spectroscopic characterization, and invitro anticancer activity of copper(II) complexes

    NASA Astrophysics Data System (ADS)

    Emam, Sanaa Moustafa; El Sayed, Ibrahim El Tantawy; Nassar, Nagla

    2015-03-01

    New generation of copper(II) complexes with aminoalkylaminoneocryptolepine as bidentate ligands has been synthesized and it is characterized by elemental analyses, magnetic moment, spectra (IR, UV-Vis, 1H NMR and ESR) and thermal studies. The IR data suggest the coordination modes for ligands which behave as a bidentate with copper(II) ion. Based on the elemental analysis, magnetic studies, electronic and ESR data, binuclear square planar geometry was proposed for complexes 7a, 7b, square pyramidal for 9a, 9b and octahedral for 8a, 8b, 10a, 10b. The molar conductance in DMF solution indicates that all complexes are electrolyte except 7a and 7b. The ESR spectra of solid copper(II) complexes in powder form showed an axial symmetry with 2B1g as a ground state and hyperfine structure. The thermal stability and degradation of the ligands and their metal complexes were studied employing DTA and TG methods. The metal-free ligands and their copper(II) complexes were tested for their in vitro anticancer activity against human colon carcinoma (HT-29). The results showed that the synthesized copper(II) complexes exhibited higher anticancer activity than their free ligands. Of all the studied copper(II) complexes, the bromo-substituted complex 9b exhibited high anticancer activity at low micromolar inhibitory concentrations (IC50 = 0.58 μM), compared to the other complexes and the free ligands.

  20. Active Learning for Directed Exploration of Complex Systems

    NASA Technical Reports Server (NTRS)

    Burl, Michael C.; Wang, Esther

    2009-01-01

    Physics-based simulation codes are widely used in science and engineering to model complex systems that would be infeasible to study otherwise. Such codes provide the highest-fidelity representation of system behavior, but are often so slow to run that insight into the system is limited. For example, conducting an exhaustive sweep over a d-dimensional input parameter space with k-steps along each dimension requires k(sup d) simulation trials (translating into k(sup d) CPU-days for one of our current simulations). An alternative is directed exploration in which the next simulation trials are cleverly chosen at each step. Given the results of previous trials, supervised learning techniques (SVM, KDE, GP) are applied to build up simplified predictive models of system behavior. These models are then used within an active learning framework to identify the most valuable trials to run next. Several active learning strategies are examined including a recently-proposed information-theoretic approach. Performance is evaluated on a set of thirteen synthetic oracles, which serve as surrogates for the more expensive simulations and enable the experiments to be replicated by other researchers.

  1. Bioengineered nisin derivatives with enhanced activity in complex matrices.

    PubMed

    Rouse, Susan; Field, Des; Daly, Karen M; O'Connor, Paula M; Cotter, Paul D; Hill, Colin; Ross, R Paul

    2012-07-01

    Nisin A is the best known and most extensively characterized lantibiotic. As it is ribosomally synthesized, bioengineering-based strategies can be used to generate variants. We have previously demonstrated that bioengineering of the hinge region of nisin A can result in the generation of variants with enhanced anti-microbial activity against Gram-positive pathogens. Here we created a larger bank of hinge variant producers and screened for producers that exhibit enhanced bioactivity as assessed by agar-based assays against a selection of target strains. Further analysis of 12 'lead' variants reveals that in many cases enhanced bioactivity is not attributable to enhanced specific activity but is instead as a consequence of an enhanced ability to diffuse through complex polymers. In the case of two variants, which contain the residues SVA and NAK, respectively, within the hinge region, we demonstrate that this enhanced trait enables the peptides to dramatically outperform nisin A with respect to controlling Listeria monocytogenes in commercially produced chocolate milk that contains carrageenan as a stabilizer. PMID:22260415

  2. ON MAGNETIC ACTIVITY BAND OVERLAP, INTERACTION, AND THE FORMATION OF COMPLEX SOLAR ACTIVE REGIONS

    SciTech Connect

    McIntosh, Scott W.; Leamon, Robert J.

    2014-11-20

    Recent work has revealed a phenomenological picture of the how the ∼11 yr sunspot cycle of the Sun arises. The production and destruction of sunspots is a consequence of the latitudinal-temporal overlap and interaction of the toroidal magnetic flux systems that belong to the 22 yr magnetic activity cycle and are rooted deep in the Sun's convective interior. We present a conceptually simple extension of this work, presenting a hypothesis on how complex active regions can form as a direct consequence of the intra- and extra-hemispheric interaction taking place in the solar interior. Furthermore, during specific portions of the sunspot cycle, we anticipate that those complex active regions may be particularly susceptible to profoundly catastrophic breakdown, producing flares and coronal mass ejections of the most severe magnitude.

  3. Serum-resistant complex nanoparticles functionalized with imidazole-rich polypeptide for gene delivery to pulmonary metastatic melanoma.

    PubMed

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

    2014-01-30

    To enhance serum-resistance and overcome the lysosomal barrier are effective and feasible strategies to increase the transfection efficiency of non-viral gene delivery system. For the systemic delivery of therapeutic gene, we previously developed self-assemble carboxymethyl poly(l-histidine) (CM-PLH)/poly(β-amino ester) (PbAE)/pDNA ternary complex nanoparticles based on electrostatic coating as an effective pDNA carrier. Recharging cationic PbAE/pDNA polyplexes with CM-PLH was a promising method to reduce the cytotoxicity and enhance the stability in vivo of positive charged polyplexes. In the present study, the transfection activities of ternary complex nanoparticles were further evaluated in vitro and in vivo. The transfection efficiency of ternary complex nanoparticles showed significant serum-resistance (CM-PLH-containing (51.9±4.35)% in 50% FBS>CM-PLH-free (14.7±5.66)% in 50% FBS), cell line dependent (HEK293>MCF-7>COS7>B16F10>A549>Hela>SPC-A1>CHO>SKOV3) and incubation period dependent (24 h, 20 h, 16 h>12 h>8 h>4 h>2 h>1 h>0.5 h). After transfected with ternary complex nanoparticles loading pGV240-MDA-7/IL-24, the B16F10 cells exhibited significant apoptosis and proliferation inhibition due to the expression of IL-24. Moreover, in the pulmonary metastatic melanoma model, ternary complex nanoparticles loading pGV240-MDA-7/IL-24 showed significant antitumor therapeutic efficacy in vivo. These results suggested that CM-PLH/PbAE/pDNA ternary complex nanoparticles were promising and challenging gene vector for practical application. PMID:24370843

  4. Thermodiffusion in binary and ternary nonpolar hydrocarbon + alcohol mixtures

    NASA Astrophysics Data System (ADS)

    Eslamian, Morteza; Saghir, M. Ziad

    2012-12-01

    Thermodiffusion in complex mixtures, such as associating, molten metal, and polymer mixtures is difficult to model usually owing to the occurrence of a sign change in the thermodiffusion coefficient when the mixture concentration and temperature change. A mixture comprised of a nonpolar hydrocarbon and an alcohol is a complex and highly non-ideal mixture. In this paper an existing binary non-equilibrium thermodynamics model (Eslamian and Saghir, Physical Review E 80, 061201, 2009) developed for aqueous mixtures of alcohols is examined against the experimental data of binary nonpolar hydrocarbon and alcohol mixtures. For ternary mixtures, non-equilibrium thermodynamic expressions developed by the authors for aqueous mixtures of alcohols (Eslamian and Saghir, Canadian Journal of Chemical Engineering, DOI 10.1002/cjce.20581) is used to predict thermodiffusion coefficients of ternary nonpolar hydrocarbon and alcohol mixtures. The rationale behind the sign change is elucidated and attributed to an anomalous change in the molecular structure and therefore viscosity of such mixtures. Model predictions of thermodiffusion coefficients of binary mixtures predict a sign change consistent with the experimental data although the model is still too primitive to capture all structural complexities. For instance, in the methanol-benzene mixture where the model predictions are poorest, the viscosity data show that when concentration varies, the mixture's molecular structure experiences a severe change twice, the first major change leading to a maximum in the thermodiffusion coefficient, whereas the second change causes a sign change.

  5. A Molecular Platform for Multistate Near-Infrared Electrochromism and Flip-Flop, Flip-Flap-Flop, and Ternary Memory.

    PubMed

    Cui, Bin-Bin; Tang, Jian-Hong; Yao, Jiannian; Zhong, Yu-Wu

    2015-08-01

    A diruthenium complex with a redox-active amine bridge has been designed, synthesized, and studied by single-crystal X-ray analysis and DFT and TDDFT calculations. It shows three well-separated redox processes with exclusive near-infrared (NIR) absorbance at each redox state. The electropolymerized film of a related vinyl-functionalized complex displays multistate NIR electrochromism with low operational potential, good contrast ratio, and long retention time. Flip-flop, flip-flap-flop, and ternary memories have been realized by using the obtained film (ca. 15-20 nm thick) with three electrochemical inputs and three NIR optical outputs that each displays three levels of signal intensity. PMID:26138863

  6. High resolution studies of complex solar active regions

    NASA Astrophysics Data System (ADS)

    Deng, Na

    Flares and Coronal Mass Ejections (CMEs) are energetic events, which can even impact the near-Earth environment and are the principal source of space weather. Most of them originate in solar active regions. The most violent events are produced in sunspots with a complex magnetic field topology. Studying their morphology and dynamics is helpful in understanding the energy accumulation and release mechanisms for flares and CMEs, which are intriguing problems in solar physics. The study of complex active regions is based on high-resolution observations from space missions and new instruments at the Big Bear Solar Observatory (BBSO). Adaptive optics (AO) in combination with image restoration techniques (speckle masking imaging) can achieve improved image quality and a spatial resolution (about 100 km on the solar surface) close to the diffraction limit of BBSO's 65 cm vacuum telescope. Dopplergrams obtained with a two-dimensional imaging spectrometer combined with horizontal flow maps derived with Local Correlation Tracking (LCT) provide precise measurements of the three-dimensional velocity field in sunspots. Magnetic field measurements from ground- and space-based instruments complement these data. At the outset of this study, the evolution and morphology of a typical round sunspot are described in some detail. The sunspot was followed from disk center to the limb, thus providing some insight into the geometry of the magnetic flux system. Having established a benchmark for a stable sunspot, the attention is turned to changes of the sunspot structure associated with flares and CMEs. Rapid penumbral decay and the strengthening of sunspot umbrae are manifestations of photospheric magnetic field changes after a flare. These sudden intensity changes are interpreted as a result of magnetic reconnection during the flare, which causes the magnetic field lines to be turned from more inclined to more vertical. Strong photospheric shear flows along the flaring magnetic

  7. Complexation study and anticellular activity enhancement by doxorubicin-cyclodextrin complexes on a multidrug-resistant adenocarcinoma cell line.

    PubMed

    Al-Omar, A; Abdou, S; De Robertis, L; Marsura, A; Finance, C

    1999-04-19

    Ability of molecular complexes of [Doxorubicin (DX)-cyclodextrin (Cd)] to enhance the anticellular activity of antineoplastic drug Doxorubicin and to reverse its multidrug resistance has been investigated. A spectroscopic study of the alpha, beta, and gamma-[DX-Cds] complexes has been investigated in relation to their biological effects on a multidrug resistant (MDR) human rectal adenocarcinoma cell line (HRT-18). A ten fold enhancement of DX anticellular activity in presence of beta-cyclodextrin alone was detected. PMID:10328296

  8. 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

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

    PubMed

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

    2016-01-01

    Complexin regulates spontaneous and activates Ca(2+)-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. PMID:27253060

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

    SciTech Connect

    Tamm, Artur; Aabloo, Alvo; Klintenberg, Mattias; Stocks, Malcolm; Caro, Alfredo

    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 for 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.

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

    DOE PAGESBeta

    Tamm, Artur; Aabloo, Alvo; Klintenberg, Mattias; Stocks, Malcolm; Caro, Alfredo

    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

  12. Activation of cutaneous immune responses in complex regional pain syndrome

    PubMed Central

    Birklein, Frank; Drummond, Peter D.; Li, Wenwu; Schlereth, Tanja; Albrecht, Nahid; Finch, Philip M.; Dawson, Linda F.; Clark, J. David; Kingery, Wade S.

    2014-01-01

    The pathogenesis of complex regional pain syndrome (CRPS) is unresolved, but TNF-α and IL-6 are elevated in experimental skin blister fluid from CRPS affected limbs, as is tryptase, a marker for mast cells. In the rat fracture model of CRPS exaggerated sensory and sympathetic neural signaling stimulate keratinocyte and mast cell proliferation, causing the local production of high levels of inflammatory cytokines leading to pain behavior. The current investigation used CRPS patient skin biopsies to determine whether keratinocyte and mast cell proliferation occur in CRPS skin and to identify the cellular source of the up-regulated TNF-α, IL-6, and tryptase observed in CRPS experimental skin blister fluid. Skin biopsies were collected from the affected skin and the contralateral mirror site in 55 CRPS patients and the biopsy sections were immunostained for keratinocyte, cell proliferation, mast cell markers, TNF-α, and IL-6. In early CRPS keratinocytes were activated in the affected skin, resulting in proliferation, epidermal thickening, and up-regulated TNF-α and IL-6 expression. In chronic CRPS there was reduced keratinocyte proliferation with epidermal thinning in the affected skin. Acute CRPS patients also had increased mast cell accumulation in the affected skin, but there was no increase in mast cell numbers in chronic CRPS. PMID:24462502

  13. Aminoglycoside activity observed on single pre-translocation ribosome complexes

    PubMed Central

    Feldman, Michael B; Terry, Daniel S; Altman, Roger B; Blanchard, Scott C

    2010-01-01

    Aminoglycoside-class antibiotics bind directly to ribosomal RNA, imparting pleiotropic effects on ribosome function. Despite in-depth structural investigations of aminoglycoside–RNA oligonucleotide and aminoglycoside-ribosome interactions, mechanisms explaining the unique ribosome inhibition profiles of chemically similar aminoglycosides remain elusive. Here, using single-molecule fluorescence resonance energy transfer (smFRET) methods, we show that high-affinity aminoglycoside binding to the conserved decoding site region of the functional pre-translocation ribosome complex specifically remodels the nature of intrinsic dynamic processes within the particle. The extents of these effects, which are distinct for each member of the aminoglycoside class, strongly correlate with their inhibition of EF-G–catalyzed translocation. Neomycin, a 4,5-linked amino-glycoside, binds with lower affinity to one or more secondary binding sites, mediating distinct structural and dynamic perturbations that further enhance translocation inhibition. These new insights help explain why closely related aminoglycosides elicit pleiotropic translation activities and demonstrate the potential utility of smFRET as a tool for dissecting the mechanisms of antibiotic action. PMID:19946275

  14. Characterisation of the active/de-active transition of mitochondrial complex I☆

    PubMed Central

    Babot, Marion; Birch, Amanda; Labarbuta, Paola; Galkin, Alexander

    2014-01-01

    Oxidation of NADH in the mitochondrial matrix of aerobic cells is catalysed by mitochondrial complex I. The regulation of this mitochondrial enzyme is not completely understood. An interesting characteristic of complex I from some organisms is the ability to adopt two distinct states: the so-called catalytically active (A) and the de-active, dormant state (D). The A-form in situ can undergo de-activation when the activity of the respiratory chain is limited (i.e. in the absence of oxygen). The mechanisms and driving force behind the A/D transition of the enzyme are currently unknown, but several subunits are most likely involved in the conformational rearrangements: the accessory subunit 39 kDa (NDUFA9) and the mitochondrially encoded subunits, ND3 and ND1. These three subunits are located in the region of the quinone binding site. The A/D transition could represent an intrinsic mechanism which provides a fast response of the mitochondrial respiratory chain to oxygen deprivation. The physiological role of the accumulation of the D-form in anoxia is most probably to protect mitochondria from ROS generation due to the rapid burst of respiration following reoxygenation. The de-activation rate varies in different tissues and can be modulated by the temperature, the presence of free fatty acids and divalent cations, the NAD+/NADH ratio in the matrix, the presence of nitric oxide and oxygen availability. Cysteine-39 of the ND3 subunit, exposed in the D-form, is susceptible to covalent modification by nitrosothiols, ROS and RNS. The D-form in situ could react with natural effectors in mitochondria or with pharmacological agents. Therefore the modulation of the re-activation rate of complex I could be a way to ameliorate the ischaemia/reperfusion damage. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Guest Editors: Manuela Pereira and Miguel Teixeira. PMID:24569053

  15. Insights into COPll Coat Nucleation from the Structure of Sec23 Sar1 Complexed with the Active Fragment of Sec31

    SciTech Connect

    Bi,X.; Mancias, J.; Goldberg, J.

    2007-01-01

    The COPII vesicular coat forms on the endoplasmic reticulum from Sar1-GTP, Sec23/24 and Sec13/31 protein subunits. Here, we define the interaction between Sec23/24{center_dot}Sar1 and Sec13/31, involving a 40 residue Sec31 fragment. In the crystal structure of the ternary complex, Sec31 binds as an extended polypeptide across a composite surface of the Sec23 and Sar1-GTP molecules, explaining the stepwise character of Sec23/24{center_dot}Sar1 and Sec13/31 recruitment to the membrane. The Sec31 fragment stimulates GAP activity of Sec23/24, and a convergence of Sec31 and Sec23 residues at the Sar1 GTPase active site explains how GTP hydrolysis is triggered leading to COPII coat disassembly. The Sec31 active fragment is accommodated in a binding groove supported in part by Sec23 residue Phe380. Substitution of the corresponding residue F382L in human Sec23A causes cranio-lenticulo-sutural dysplasia, and we suggest that this mutation disrupts the nucleation of COPII coat proteins at endoplasmic reticulum exit sites.

  16. Formation of a Trimeric Xpo1-Ran[GTP]-Ded1 Exportin Complex Modulates ATPase and Helicase Activities of Ded1.

    PubMed

    Hauk, Glenn; Bowman, Gregory D

    2015-01-01

    The DEAD-box RNA helicase Ded1, which is essential in yeast and known as DDX3 in humans, shuttles between the nucleus and cytoplasm and takes part in several basic processes including RNA processing and translation. A key interacting partner of Ded1 is the exportin Xpo1, which together with the GTP-bound state of the small GTPase Ran, facilitates unidirectional transport of Ded1 out of the nucleus. Here we demonstrate that Xpo1 and Ran[GTP] together reduce the RNA-stimulated ATPase and helicase activities of Ded1. Binding and inhibition of Ded1 by Xpo1 depend on the affinity of the Ded1 nuclear export sequence (NES) for Xpo1 and the presence of Ran[GTP]. Association with Xpo1/Ran[GTP] reduces RNA-stimulated ATPase activity of Ded1 by increasing the apparent KM for the RNA substrate. Despite the increased KM, the Ded1:Xpo1:Ran[GTP] ternary complex retains the ability to bind single stranded RNA, suggesting that Xpo1/Ran[GTP] may modulate the substrate specificity of Ded1. These results demonstrate that, in addition to transport, exportins such as Xpo1 also have the capability to alter enzymatic activities of their cargo. PMID:26120835

  17. Ternary Composite of Hemin, Gold Nanoparticles and Graphene for Highly Efficient Decomposition of Hydrogen Peroxide

    PubMed Central

    Lv, Xincong; Weng, Jian

    2013-01-01

    A ternary composite of hemin, gold nanoparticles and graphene is prepared by a two-step process. Firstly, graphene-hemin composite is synthesized through π-π interaction and then hydrogen tetracholoroauric acid is reduced in situ by ascorbic acid. This ternary composite shows a higher catalytic activity for decomposition of hydrogen peroxide than that of three components alone or the mixture of three components. The Michaelis constant of this composite is 5.82 times lower and the maximal reaction velocity is 1.81 times higher than those of horseradish peroxidase, respectively. This composite also shows lower apparent activation energy than that of other catalysts. The excellently catalytic performance could be attributed to the fast electron transfer on the surface of graphene and the synergistic interaction of three components, which is further confirmed by electrochemical characterization. The ternary composite has been used to determine hydrogen peroxide in three real water samples with satisfactory results. PMID:24257652

  18. Ternary fission induced by polarized neutrons

    NASA Astrophysics Data System (ADS)

    Gönnenwein, Friedrich

    2013-12-01

    Ternary fission of (e,e) U- and Pu- isotopes induced by cold polarized neutrons discloses some new facets of the process. In the so-called ROT effect shifts in the angular distributions of ternary particles relative to the fission fragments show up. In the so-called TRI effect an asymmetry in the emission of ternary particles relative to a plane formed by the fragment momentum and the spin of the neutron appear. The two effects are shown to be linked to the components of angular momentum perpendicular and parallel to the fission axis at the saddle point of fission. Based on theoretical models the spectroscopic properties of the collective transitional states at the saddle point are inferred from experiment.

  19. Optimal Symmetric Ternary Quantum Encryption Schemes

    NASA Astrophysics Data System (ADS)

    Wang, Yu-qi; She, Kun; Huang, Ru-fen; Ouyang, Zhong

    2016-07-01

    In this paper, we present two definitions of the orthogonality and orthogonal rate of an encryption operator, and we provide a verification process for the former. Then, four improved ternary quantum encryption schemes are constructed. Compared with Scheme 1 (see Section 2.3), these four schemes demonstrate significant improvements in term of calculation and execution efficiency. Especially, under the premise of the orthogonal rate ɛ as secure parameter, Scheme 3 (see Section 4.1) shows the highest level of security among them. Through custom interpolation functions, the ternary secret key source, which is composed of the digits 0, 1 and 2, is constructed. Finally, we discuss the security of both the ternary encryption operator and the secret key source, and both of them show a high level of security and high performance in execution efficiency.

  20. Electrically active sulfur-defect complexes in sulfur implanted diamond

    NASA Astrophysics Data System (ADS)

    Kalish, R.; Uzan-Saguy, C.; Walker, R.; Prawer, S.

    2003-09-01

    Single crystal type IIa <100> diamonds were implanted with sulfur, phosphorus, and argon ions under different implantation and annealing conditions. Shallow (sub-MeV) as well as deep (MeV) implantations into samples held at low (liquid nitrogen) ambient (room temperature) and high (400 °C) temperatures were employed. The implanted samples were subjected to postimplantation annealing up to 1000 °C. Following each processing step the samples were subjected to (i) Raman spectroscopy, in order to investigate the implantation related residual defects, and (ii) electrical (resistivity and sometimes Hall effect) measurements as function of temperature. The correlation between the results of these structural and electrical measurements and the comparison of results obtained under identical processing conditions for possible n-type dopant ion-implantations (S and P) and inert (Ar) ion-implantations, as controls, leads to the following conclusions: (a) Sulfur implanted samples always exhibit at least one order of magnitude higher conductivity than Ar control implanted samples. The activation energy associated with the S related conductivity is 0.32-0.37 eV whereas that of the Ar control is 0.5 to 0.6 eV. Hall effect shows, for selected cases, n-type conductivity with low carrier concentration and mobility. (b) Although the presence of some residual defects (mainly split interstitials) seems to accompany the appearance of the S related electrical activity, the level of residual damage in the S implanted samples is always less than that of the Ar control. (c) The electrical effects due to the implantation of S vanish upon annealing at temperatures in access of 800 °C. (d) No significant difference in the electrical properties between P and control Ar implantations are evident. It is concluded that a sulfur-defect related complex, which decomposes at T>800 °C, is responsible for the electrical effects in S implanted diamond. The presence of B contamination which has

  1. Alkene to carbyne: tandem Lewis acid activation and dehydrogenation of a molybdenum ethylene complex.

    PubMed

    Stennett, Tom E; Haddow, Mairi F; Wass, Duncan F

    2013-10-18

    Carbyne formation: Treatment of a molybdenum ethylene complex with B(C6 F5 )3 induces ditopic activation of an ethylene ligand and acceptor-assisted ethane elimination to generate a novel type of zwitterionic carbyne complex. PMID:24038792

  2. Ternary fission of nuclei into comparable fragments

    SciTech Connect

    Karpeshin, F. F.

    2015-07-15

    The problem of nuclear fission into three comparable fragments is considered. A mechanism of true ternary fission is proposed. In contrast to sequential fission, where the three fragments arise upon two sequential events of binary fission, the mechanism in question relies on a scenario that originally involves fission into three fragments. This mechanism is driven by a hexadecapole deformation of the fissioning nucleus, in contrast to binary fission associated with quadrupole vibrations of the nuclear surface. The fragment-mass ratios are estimated. The dynamics of formation of collinear fragments and their subsequent motion in opposite directions is traced. The calculated probability of true ternary fission complies with observed values.

  3. 75 FR 61857 - Statement on Sound Practices Concerning Elevated Risk Complex Structured Finance Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-06

    ... Finance Activities AGENCY: Office of Thrift Supervision (OTS), Treasury. ACTION: Notice and request for... Elevated Risk Complex Structured Finance Activities. OMB Number: 1550-0111. Form Number: N/A. Description: Statement on Sound Practices Concerning Elevated Risk Complex Structured Finance Activities describes...

  4. Complex explosive volcanic activity on the Moon within Oppenheimer crater

    NASA Astrophysics Data System (ADS)

    Bennett, Kristen A.; Horgan, Briony H. N.; Gaddis, Lisa R.; Greenhagen, Benjamin T.; Allen, Carlton C.; Hayne, Paul O.; Bell, James F.; Paige, David A.

    2016-07-01

    Oppenheimer crater is a floor-fractured crater located within the South Pole-Aitken basin on the Moon, and exhibits more than a dozen localized pyroclastic deposits associated with the fractures. Localized pyroclastic volcanism on the Moon is thought to form as a result of intermittently explosive Vulcanian eruptions under low effusion rates, in contrast to the higher-effusion rate, Hawaiian-style fire fountaining inferred to form larger regional deposits. We use Lunar Reconnaissance Orbiter Camera images and Diviner Radiometer mid-infrared data, Chandrayaan-1 orbiter Moon Mineralogy Mapper near-infrared spectra, and Clementine orbiter Ultraviolet/visible camera images to test the hypothesis that the pyroclastic deposits in Oppenheimer crater were emplaced via Vulcanian activity by constraining their composition and mineralogy. Mineralogically, we find that the deposits are variable mixtures of orthopyroxene and minor clinopyroxene sourced from the crater floor, juvenile clinopyroxene, and juvenile iron-rich glass, and that the mineralogy of the pyroclastics varies both across the Oppenheimer deposits as a whole and within individual deposits. We observe similar variability in the inferred iron content of pyroclastic glasses, and note in particular that the northwest deposit, associated with Oppenheimer U crater, contains the most iron-rich volcanic glass thus far identified on the Moon, which could be a useful future resource. We propose that this variability in mineralogy indicates variability in eruption style, and that it cannot be explained by a simple Vulcanian eruption. A Vulcanian eruption should cause significant country rock to be incorporated into the pyroclastic deposit; however, large areas within many of the deposits exhibit spectra consistent with high abundances of juvenile phases and very little floor material. Thus, we propose that at least the most recent portion of these deposits must have erupted via a Strombolian or more continuous fire

  5. Microstructural Investigations On Ni-Ta-Al Ternary Alloys

    SciTech Connect

    Negache, M.; Souami, N.

    2010-01-05

    The Ni-Al-Ta ternary alloys in the Ni-rich part present complex microstructures. They are composed of multiple phases that are formed according to the nominal composition of the alloy, primary Ni(gamma), Ni{sub 3}Al(gamma'), Ni{sub 6}AlTa(tau{sub 3}), Ni{sub 3}Ta(delta) or in equilibrium: two solid phases (gamma'-tau{sub 3}), (tau{sub 3}-delta), (tau{sub 3}-gamma), (gamma-delta) or three solid phases (gamma'-tau{sub 3}-delta). The nature and the volume fraction of these phases give these alloys very interesting properties at high temperature, and this makes them attractive for specific applications. We have developed a series of ternary alloys in electric arc furnace, determining their solidification sequences using Differential Thermal Analysis (DTA), characterized by SEM-EDS, X-ray diffraction and by a microhardness tests. The follow-up results made it possible to make a correlation between the nature of the formed phases and their solidifying way into the Ni{sub 75}Al{sub x}Ta{sub y} (x+y = 25at.%) system, which are varied and complex. In addition to the solid solution Ni (gamma), the formed intermetallics compounds (gamma', tau{sub 3} and delta) has been identified and correlated with a complex balance between phases.We noticed that the hardness increases with the tantalum which has a hardening effect and though the compound Ni{sub 3}Ta(delta) is the hardest. The below results provide a better understanding of the complex microstructure of these alloys.

  6. Tailoring fly ash activated with bentonite as adsorbent for complex wastewater treatment

    NASA Astrophysics Data System (ADS)

    Visa, Maria

    2012-12-01

    Used as adsorbent, alkali fly ash represents a low cost solution for advanced wastewater treatment. The alkali treatment raises sustainability issues therefore, in this research we aim to replace alkali fly ash with washed fly ash (FAw). For improving the adsorption capacity of washed fly ash, bentonite powder (B) was added, as a natural adsorbent with a composition almost identical to the fly ash. The new adsorbent was characterized by AFM, XRD, FTIR, SEM, EDS and the surface energy was evaluated by contact angle measurements. For understanding the complex adsorption process on this mixed substrate, preliminary tests were developed on synthetic wastewaters containing a single pollutant system (heavy metal), binary (two-heavy metals) and ternary (dye and two heavy metals) systems. Experiments were done on synthetic wastewaters containing methylene blue, cadmium and copper, using FAw, B and their powder mixtures. The pseudo-second order kinetics could well model all the processes, indicating a good adsorbent material which can be used for the pollutants removal from wastewater. After adsorption the substrates loaded with pollutants, annealed at 500 °C can be reused for padding in stone blocks.

  7. Ternary rare earth-lanthanide sulfides

    DOEpatents

    Takeshita, Takuo; Gschneidner JR., Karl A.; Beaudry, Bernard J.

    1987-01-06

    A new ternary rare earth sulfur compound having the formula: where M is a rare earth element selected from the group europium, samarium and ytterbium and x=0.15 to 0.8. The compound has good high-temperature thermoelectric properties and exhibits long-term structural stability up to 1000.degree. C.

  8. Ternary Dy-Er-Al magnetic refrigerants

    DOEpatents

    Gschneidner, Jr., Karl A.; Takeya, Hiroyuki

    1995-07-25

    A ternary magnetic refrigerant material comprising (Dy.sub.1-x Er.sub.x)Al.sub.2 for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant.

  9. Ternary Dy-Er-Al magnetic refrigerants

    DOEpatents

    Gschneidner, K.A. Jr.; Takeya, Hiroyuki

    1995-07-25

    A ternary magnetic refrigerant material comprising (Dy{sub 1{minus}x}Er{sub x})Al{sub 2} for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant. 29 figs.

  10. Does Science Also Prefer a Ternary Pattern?

    ERIC Educational Resources Information Center

    Pogliani, L.; Klein, D. J.; Balaban, A. T.

    2006-01-01

    Through the importance of the number three in our culture and the strange preference for a ternary pattern of our nature one can perceive how and why number theory degraded to numerology. The strong preference of our minds for simple patterns can be read as the key to understanding not only the development of numerology, but also why scientists…

  11. TERNARY ALLOYS OF URANIUM, COLUMBIUM, AND ZIRCONIUM

    DOEpatents

    Foote, F.G.

    1960-08-01

    Ternary alloys of uranium are described which are useful as neutron- reflecting materials in a fast neutron reactor. They are especially resistant to corrosion caused by oxidative processes of gascous or aqueous origin and comprise uranium as the predominant metal with zirconiunn and niobium wherein the total content of the minor alloying elements is between 2 and 8% by weight.

  12. Binding Energy Calculations for Novel Ternary Ionic Lattices

    NASA Astrophysics Data System (ADS)

    Rodríguez-Mijangos, Ricardo; Vazquez-Polo, Gustavo

    2002-03-01

    Theoretical calculations for the binding energy between metalic ions and negative ions on a novel ternary ionic lattice is carried out for several solid solutions prepared with different concentrations and characterized recently (1). The ternary lattices that reach a good miscibility are: KCl(x)KBr(y)RbCl(z) in three different concentrations: (x=y=z=0.33), (x=0.5, y=0.25, z=0.25) and (x=0.33, y=0.07, z=0.60). The binding energy for these novel structures is calculated from the lattice constants obtained by X ray diffractometry analysis performed on the samples and the Vegard law (2). For the repulsive force exponent m, an average of the m values was considered. The energy values obtained by the Born´expression are compared with corresponding energy values from the lattice with more complex expressions, such as the Born Mayer, Born-Van der Walls. There is a good aggreement between all these calculations. (1)R. R. Mijangos, A. Cordero-Borboa, E. Alvarez, M. Cervantes, Physics Letters A 282 (2001) 195-200. (2) G. Vazquez-Polo, R. R. Mijangos et al. Revista Mexicana de Fisica, 47, Diciembre 2001. In Press.

  13. Activated sampling in complex materials at finite temperature: The properly obeying probability activation-relaxation technique

    NASA Astrophysics Data System (ADS)

    Vocks, Henk; Chubynsky, M. V.; Barkema, G. T.; Mousseau, Normand

    2005-12-01

    While the dynamics of many complex systems is dominated by activated events, there are very few simulation methods that take advantage of this fact. Most of these procedures are restricted to relatively simple systems or, as with the activation-relaxation technique (ART), sample the conformation space efficiently at the cost of a correct thermodynamical description. We present here an extension of ART, the properly obeying probability ART (POP-ART), that obeys detailed balance and samples correctly the thermodynamic ensemble. Testing POP-ART on two model systems, a vacancy and an interstitial in crystalline silicon, we show that this method recovers the proper thermodynamical weights associated with the various accessible states and is significantly faster than molecular dynamics in the simulations of a vacancy below 700 K.

  14. Activated sampling in complex materials at finite temperature: the properly obeying probability activation-relaxation technique.

    PubMed

    Vocks, Henk; Chubynsky, M V; Barkema, G T; Mousseau, Normand

    2005-12-22

    While the dynamics of many complex systems is dominated by activated events, there are very few simulation methods that take advantage of this fact. Most of these procedures are restricted to relatively simple systems or, as with the activation-relaxation technique (ART), sample the conformation space efficiently at the cost of a correct thermodynamical description. We present here an extension of ART, the properly obeying probability ART (POP-ART), that obeys detailed balance and samples correctly the thermodynamic ensemble. Testing POP-ART on two model systems, a vacancy and an interstitial in crystalline silicon, we show that this method recovers the proper thermodynamical weights associated with the various accessible states and is significantly faster than molecular dynamics in the simulations of a vacancy below 700 K. PMID:16396563

  15. Synthesis, characterization, and molecular structures of binary and ternary copper (I) complexes with 1,5-cyclooctadiene (cod): (Cu(cod) sub 2 )ClO sub 4 and (Cu(cod)(2,2 prime -bipyridine))PF sub 6

    SciTech Connect

    Munakata, Megumu; Kitagawa, Susumu; Shimono, Hisao; Masuda, Hideki )

    1991-06-12

    Binary and ternary copper (I) complexes with 1,5-cyclooctadiene (cod), (Cu(cod){sub 2})ClO{sub 4} (1) and (Cu(cod)(bpy))PF{sub 6} (2) (bpy = 2,2{prime}-bipyridine) have been prepared. The crystal structures have been determined by using single-crystal X-ray diffraction methods. The geometry about the Cu atom coordinated to the four olefinic moieties of the two cod molecules is quasi-tetrahedral in 1. The Cu-C(olefin) distances of 2,27 {angstrom} (average) are significantly longer than those found for copper (I) olefin complexes, and the C{double bond}C bond distances of 1.33 {angstrom} (average) of the coordinated cod are almost the same that of free cod. On the basis of the C{double bond}C distance, the stretching frequencies of the C{double bond}C bonds and the {sup 1}H NMR chemical shifts of the olefinia protons, the Cu-olefin bonds in 1 were concluded to be dominated by {sigma} donation from the olefinic moiety to the copper. The geometry about the Cu atom coordinated to two nitrogen atoms of boy and two olefinic moiety of the cod molecule are significantly shorter than those of the other olefinic moiety (2.44 {angstrom} (average). In response to this, the C{double bond}C distance (1.36 (1) {angstrom}) of the former is longer than that (1.33) (1) {angstrom}) of the latter. 32 refs., 5 figs., 6 tabs.

  16. Recent Progress in Some Active Topics on Complex Networks

    NASA Astrophysics Data System (ADS)

    Gu, J.; Zhu, Y.; Guo, L.; Jiang, J.; Chi, L.; Li, W.; Wang, Q. A.; Cai, X.

    2015-04-01

    Complex networks have been extensively studied across many fields, especially in interdisciplinary areas. It has since long been recognized that topological structures and dynamics are important aspects for capturing the essence of complex networks. The recent years have also witnessed the emergence of several new elements which play important roles in network study. By combining the results of different research orientations in our group, we provide here a review of the recent advances in regards to spectral graph theory, opinion dynamics, interdependent networks, graph energy theory and temporal networks. We hope this will be helpful for the newcomers of those fields to discover new intriguing topics.

  17. Synergistic Effects of Morphological Control and Complementary Absorption in Efficient All-Small-Molecule Ternary-Blend Solar Cells.

    PubMed

    Farahat, Mahmoud E; Patra, Dhananjaya; Lee, Chih-Hao; Chu, Chih-Wei

    2015-10-14

    In this study, we combined two small-molecule donors-a diketopyrrolopyrrole-based small molecule (SMD) and a benzodithiophene-based molecule (BDT6T)-with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) to form ternary blend solar cells. The power conversion efficiency of the binary SMD:PC61BM bulk heterojunction solar cell improved from 4.57 to 6.28% after adding an appropriate amount BDT6T as a guest. We attribute this 37% improvement in device performance to the complementary absorption behavior of BDT6T and SMD, as evidenced by the increase in the short circuit current. After addition of BDT6T to form the ternary blend, the crystallinity and morphology of the active layer were enhanced. For example, the features observed in the ternary active layers were finer than those in the binary blends. This means that BDT6T as a third component in the ternary blend has effective role on both the absorption and the morphology. In addition, adding BDT6T to form the ternary blend also led to an increase in the open-circuit voltage. Our findings suggest that the preparation of such simple all-small-molecule ternary blends can be an effective means of improving the efficiency of photovoltaic devices. PMID:26389528

  18. Design of a novel quantum reversible ternary up-counter

    NASA Astrophysics Data System (ADS)

    Houshmand, Pouran; Haghparast, Majid

    2015-08-01

    Reversible logic has been recently considered as an interesting and important issue in designing combinational and sequential circuits. The combination of reversible logic and multi-valued logic can improve power dissipation, time and space utilization rate of designed circuits. Only few works have been reported about sequential reversible circuits and almost there are no paper exhibited about quantum ternary reversible counter. In this paper, first we designed 2-qutrit and 3-qutrit quantum reversible ternary up-counters using quantum ternary reversible T-flip-flop and quantum reversible ternary gates. Then we proposed generalized quantum reversible ternary n-qutrit up-counter. We also introduced a new approach for designing any type of n-qutrit ternary and reversible counter. According to the results, we can conclude that applying second approach quantum reversible ternary up-counter is better than the others.

  19. Quantification of Outer-Sphere Macrochelate Formation in the Ternary cis-Diammine-Platinum(II)-Bis-2'-deoxyguanosine 5'-Monophosphate Complex, cis-(NH(3))(2)Pt(dGMP)(2)(2)(-), and Formation of Quaternary Mixed Metal Ion Species with Magnesium(II), Copper(II), or Zinc(II) in Aqueous Solution.

    PubMed

    Song, Bin; Oswald, Gerda; Zhao, Jing; Lippert, Bernhard; Sigel, Helmut

    1998-09-21

    The acid-base properties of cis-(NH(3))(2)Pt(dG)(2)(2)(-), where both dG(2)(-) (=2'-deoxyguanosine 5'-monophosphate) are N7-coordinated to the same Pt(II) [the complex is abbreviated as Pt(dG)(2)(2)(-)], are summarized [on the basis of potentiometric pH titration data from B. Song et al. (Metal-Based Drugs 1996, 3, 131-141)] and a micro acidity constant scheme is developed which allows quantification of the intrinsic acidity of the two P(O)(2)(OH)(-) groups present in this ternary complex (I = 0.1 M, NaNO(3); 25 degrees C). On the basis of comparisons with the corresponding acid-base properties of cis-(NH(3))(2)Pt(dCMP.H-N3)(2) [(dCMP.H)(-) = phosphate-monoprotonated 2'-deoxycytidine 5'-monophosphate] it is concluded that intramolecular, outer-sphere macrochelates form via Pt(NH(3)).O(3)P hydrogen bonds. The formation degree of these macrochelates is quantified; it amounts in aqueous solution in each case (in its lower limit) to about 40% for the various possibilities which exist for the formation of these chelates in the cis-(NH(3))(2)Pt(dG)(2) complexes. The stability constants of the mixed metal ion complexes, M[Pt(H;dG)(dG)](+) and M[Pt(dG)(2)], were also determined via potentiometric pH titrations. On the basis of previous measurements with simple phosphate monoesters and phosphonate derivatives, i.e., R-PO(3)(2)(-) with R being a noncoordinating residue (Sigel, H.; et al., Helv. Chim. Acta 1992, 75, 2634-2656), it is shown that the stability of the two mixed metal ion complexes is largely governed by the basicity of the phosphate groups (as quantified via the mentioned microconstants) indicating that the effect of the N7-bound Pt(II) on the phosphate-metal ion binding properties is relatively small. These results suggest that, e.g., a metal ion bound to a nucleobase residue in a nucleotide or in a nucleic acid affects only slightly the metal ion binding capabilities of its phosphate residue or its phosphate backbone. PMID:11670649

  20. Ternary NiFeMn layered double hydroxides as highly-efficient oxygen evolution catalysts.

    PubMed

    Lu, Zhiyi; Qian, Li; Tian, Yang; Li, Yaping; Sun, Xiaoming; Duan, Xue

    2016-01-18

    Layered double hydroxides (LDHs) are a family of layer materials that receive heightened attention. Herein a ternary NiFeMn-LDH is investigated with superior oxygen evolution activity, which is attributed to the Mn(4+) doping in the intralayer, which modifies the electronic structure and improves the conductivity of the electrocatalyst. PMID:26579843

  1. Active Site Structure and Peroxidase Activity of Oxidatively Modified Cytochrome c Species in Complexes with Cardiolipin.

    PubMed

    Capdevila, Daiana A; Oviedo Rouco, Santiago; Tomasina, Florencia; Tortora, Verónica; Demicheli, Verónica; Radi, Rafael; Murgida, Daniel H

    2015-12-29

    We report a resonance Raman and UV-vis characterization of the active site structure of oxidatively modified forms of cytochrome c (Cyt-c) free in solution and in complexes with cardiolipin (CL). The studied post-translational modifications of Cyt-c include methionine sulfoxidation and tyrosine nitration, which lead to altered heme axial ligation and increased peroxidase activity with respect to those of the wild-type protein. In spite of the structural and activity differences between the protein variants free in solution, binding to CL liposomes induces in all cases the formation of a spectroscopically identical bis-His axial coordination conformer that more efficiently promotes lipid peroxidation. The spectroscopic results indicate that the bis-His form is in equilibrium with small amounts of high-spin species, thus suggesting a labile distal His ligand as the basis for the CL-induced increase in enzymatic activity observed for all protein variants. For Cyt-c nitrated at Tyr74 and sulfoxidized at Met80, the measured apparent binding affinities for CL are ∼4 times larger than for wild-type Cyt-c. On the basis of these results, we propose that these post-translational modifications may amplify the pro-apoptotic signal of Cyt-c under oxidative stress conditions at CL concentrations lower than for the unmodified protein. PMID:26620444

  2. Immune complexes that contain HIV antigens activate peripheral blood T cells.

    PubMed

    Korolevskaya, L B; Shmagel, K V; Saidakova, E V; Shmagel, N G; Chereshnev, V A

    2016-07-01

    Uninfected donor T cells were treated in vitro by model immune complexes that contained either HIV or hepatitis C virus (HCV) antigens. Unlike HCV antigen-containing complexes, the immune complexes that contained HIV antigens have been shown to activate peripheral blood T cells of uninfected donors under in vitro conditions. Both the antiviral antibodies and HIV antigen were involved in the activation process. The unique properties of the immune complexes formed by HIV antigens and antiviral antibodies are believed to result from the virus-specific antibody properties and molecular conformation of the antigen-antibody complex. PMID:27595830

  3. Fast isolation of highly active photosystem II core complexes from spinach.

    PubMed

    Wang, Zhao-Gai; Xu, Tian-Hua; Liu, Cheng; Yang, Chun-Hong

    2010-09-01

    Purification of photosystem II (PSII) core complexes is a time-consuming and low-efficiency process. In order to isolate pure and active PSII core complexes in large amounts, we have developed a fast method to isolate highly active monomeric and dimeric PSII core complexes from spinach leaves by using sucrose gradient ultracentrifugation. By using a vertical rotor the process was completed significantly faster compared with a swing-out rotor. In order to keep the core complexes in high activity, the whole isolation procedure was performed in the presence of glycine betain and pH at 6.3. The isolated pigment-protein complexes were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, absorption spectroscopy, 77 K fluorescence spectroscopy and high performance liquid chromatography. Our results show that this method is a better choice for quick and efficient isolation of functionally active PSII core complexes. PMID:20738723

  4. Characterization and Antioxidant Activity of Quercetin/Methyl-β-Cyclodextrin Complexes.

    PubMed

    Güleç, Kadri; Demirel, Müzeyyen

    2016-01-01

    Quercetin (Qu), a polyphenolic flavonoid, is one of the most effective plant originated antioxidants. Despite the potential use of Qu in clinical trials, low water solubility, stability problems and the scarcity of cellular bioavailability limit its applications. The purpose of this study was to enhance aqueous solubility, dissolution rate and antioxidant activity of Qu by complexation with Methyl-β- cyclodextrin (M-β-CD). Analyses results showed that the aqueous solubility, dissolution rate and antioxidant activity of the complex were increased 254-fold, ~3-fold and 10% respectively compared to the pure Qu. Complexes were prepared by freeze-drying and evaporation method. The characteristics of the complexes were evaluated by DSC, XRD, (1)H-NMR, FT-IR, SEM, encapsulation efficacy, in-vitro dissolution rate analyses. Antioxidant activity studies on complexes carried out with DPPH tests. Analyses results showed that the formation of the complexes resulted in enhanced solubility with increased its antioxidant activity of Qu. PMID:26521654

  5. Antimalarial, antimicrobial, cytotoxic, DNA interaction and SOD like activities of tetrahedral copper(II) complexes.

    PubMed

    Mehta, Jugal V; Gajera, Sanjay B; Patel, Mohan N

    2014-11-01

    The mononuclear copper(II) complexes with P, O-donor ligand and different fluoroquinolones have been synthesized and characterized by elemental analysis, electronic spectra, TGA, EPR, FT-IR and LC-MS spectroscopy. An antimicrobial efficiency of the complexes has been tested against five different microorganisms in terms of minimum inhibitory concentration (MIC) and displays very good antimicrobial activity. The binding strength and binding mode of the complexes with Herring Sperm DNA (HS DNA) have been investigated by absorption titration and viscosity measurement studies. The studies suggest the classical intercalative mode of DNA binding. Gel electrophoresis assay determines the ability of the complexes to cleave the supercoiled form of pUC19 DNA. Synthesized complexes have been tested for their SOD mimic activity using nonenzymatic NBT/NADH/PMS system and found to have good antioxidant activity. All the complexes show good cytotoxic and in vitro antimalarial activities. PMID:25467683

  6. Antimalarial, antimicrobial, cytotoxic, DNA interaction and SOD like activities of tetrahedral copper(II) complexes

    NASA Astrophysics Data System (ADS)

    Mehta, Jugal V.; Gajera, Sanjay B.; Patel, Mohan N.

    2015-02-01

    The mononuclear copper(II) complexes with P, O-donor ligand and different fluoroquinolones have been synthesized and characterized by elemental analysis, electronic spectra, TGA, EPR, FT-IR and LC-MS spectroscopy. An antimicrobial efficiency of the complexes has been tested against five different microorganisms in terms of minimum inhibitory concentration (MIC) and displays very good antimicrobial activity. The binding strength and binding mode of the complexes with Herring Sperm DNA (HS DNA) have been investigated by absorption titration and viscosity measurement studies. The studies suggest the classical intercalative mode of DNA binding. Gel electrophoresis assay determines the ability of the complexes to cleave the supercoiled form of pUC19 DNA. Synthesized complexes have been tested for their SOD mimic activity using nonenzymatic NBT/NADH/PMS system and found to have good antioxidant activity. All the complexes show good cytotoxic and in vitro antimalarial activities.

  7. Antimalarial and antimicrobial activities of 8-Aminoquinoline-Uracils metal complexes

    PubMed Central

    Phopin, Kamonrat; Sinthupoom, Nujarin; Treeratanapiboon, Lertyot; Kunwittaya, Sarun; Prachayasittikul, Supaluk; Ruchirawat, Somsak; Prachayasittikul, Virapong

    2016-01-01

    8-Aminoquinoline (8AQ) derivatives have been reported to have antimalarial, anticancer, and antioxidant activities. This study investigated the potency of 8AQ-5-substituted (iodo and nitro) uracils metal (Mn, Cu, Ni) complexes (1-6) as antimalarial and antimicrobial agents. Interestingly, all of these metal complexes (1-6) showed fair antimalarial activities. Moreover, Cu complexes 2 (8AQ-Cu-5Iu) and 5 (8AQ-Cu-5Nu) exerted antimicrobial activities against Gram-negative bacteria including P. shigelloides and S. dysenteriae. The results reveal application of 8AQ and its metal complexes as potential compounds to be further developed as novel antimalarial and antibacterial agents. PMID:27103894

  8. Plasticity of TOM complex assembly in skeletal muscle mitochondria in response to chronic contractile activity.

    PubMed

    Joseph, Anna-Maria; Hood, David A

    2012-03-01

    We investigated the assembly of the TOM complex within skeletal muscle under conditions of chronic contractile activity-induced mitochondrial biogenesis. Tom40 import into mitochondria was increased by chronic contractile activity, as was its time-dependent assembly into the TOM complex. These changes coincided with contractile activity-induced augmentations in the expression of key protein import machinery components Tim17, Tim23, and Tom22, as well as the cytosolic chaperone Hsp90. These data indicate the adaptability of the TOM protein import complex and suggest a regulatory role for the assembly of this complex in exercise-induced mitochondrial biogenesis. PMID:22142511

  9. Antileishmanial activity of ruthenium(II)tetraammine nitrosyl complexes.

    PubMed

    Pereira, José Clayston Melo; Carregaro, Vanessa; Costa, Diego Luís; da Silva, João Santana; Cunha, Fernando Q; Franco, Douglas Wagner

    2010-09-01

    The complexes trans-[Ru(NO)(NH(3))(4)L](X)(3) (X = BF(4)(-), PF(6)(-) or Cl(-) and L = N-heterocyclic ligands, P(OEt)(3), SO(3)(-2)), and [Ru(NO)Hedta)] were shown to exhibit IC(50pro) in the range of 36 (L = imN) to 5000 microM (L = imC). The inhibitory effects of trans-[Ru(NO)(NH(3))(4)imN](BF(4))(3) and of the Angeli's salt on the growth of the intramacrophage amastigote form studied were found to be similar while the trans-[Ru(NH(3))(4)imN(H(2)O)](2+) complex was found not to exhibit any substantial antiamastigote effect. The trans-[Ru(NO)(NH(3))(4)imN](BF(4))(3) compound, administered (500 nmol kg(-1) day(-1)) in BALB/c mice infected with Leishmania major, was found to exhibit a 98% inhibition on the parasite growth. Furthermore, this complex proved to be at least 66 times more efficient than glucantime in in vivo experiments. PMID:20598778

  10. Generalization of the Activated Complex Theory of Reaction Rates. I. Quantum Mechanical Treatment

    DOE R&D Accomplishments Database

    Marcus, R. A.

    1964-01-01

    In its usual form activated complex theory assumes a quasi-equilibrium between reactants and activated complex, a separable reaction coordinate, a Cartesian reaction coordinate, and an absence of interaction of rotation with internal motion in the complex. In the present paper a rate expression is derived without introducing the Cartesian assumption. The expression bears a formal resemblance to the usual one and reduces to it when the added assumptions of the latter are introduced.

  11. Modeling complexity in pathologist workload measurement: the Automatable Activity-Based Approach to Complexity Unit Scoring (AABACUS).

    PubMed

    Cheung, Carol C; Torlakovic, Emina E; Chow, Hung; Snover, Dale C; Asa, Sylvia L

    2015-03-01

    Pathologists provide diagnoses relevant to the disease state of the patient and identify specific tissue characteristics relevant to response to therapy and prognosis. As personalized medicine evolves, there is a trend for increased demand of tissue-derived parameters. Pathologists perform increasingly complex analyses on the same 'cases'. Traditional methods of workload assessment and reimbursement, based on number of cases sometimes with a modifier (eg, the relative value unit (RVU) system used in the United States), often grossly underestimate the amount of work needed for complex cases and may overvalue simple, small biopsy cases. We describe a new approach to pathologist workload measurement that aligns with this new practice paradigm. Our multisite institution with geographically diverse partner institutions has developed the Automatable Activity-Based Approach to Complexity Unit Scoring (AABACUS) model that captures pathologists' clinical activities from parameters documented in departmental laboratory information systems (LISs). The model's algorithm includes: 'capture', 'export', 'identify', 'count', 'score', 'attribute', 'filter', and 'assess filtered results'. Captured data include specimen acquisition, handling, analysis, and reporting activities. Activities were counted and complexity units (CUs) generated using a complexity factor for each activity. CUs were compared between institutions, practice groups, and practice types and evaluated over a 5-year period (2008-2012). The annual load of a clinical service pathologist, irrespective of subspecialty, was ∼40,000 CUs using relative benchmarking. The model detected changing practice patterns and was appropriate for monitoring clinical workload for anatomical pathology, neuropathology, and hematopathology in academic and community settings, and encompassing subspecialty and generalist practices. AABACUS is objective, can be integrated with an LIS and automated, is reproducible, backwards compatible

  12. Recognizing Complex Upper Extremity Activities Using Body Worn Sensors

    PubMed Central

    Lemmens, Ryanne J. M.; Janssen-Potten, Yvonne J. M.; Timmermans, Annick A. A.; Smeets, Rob J. E. M.; Seelen, Henk A. M.

    2015-01-01

    To evaluate arm-hand therapies for neurological patients it is important to be able to assess actual arm-hand performance objectively. Because instruments that measure the actual quality and quantity of specific activities in daily life are lacking, a new measure needs to be developed. The aims of this study are to a) elucidate the techniques used to identify upper extremity activities, b) provide a proof-of-principle of this method using a set of activities tested in a healthy adult and in a stroke patient, and c) provide an example of the method’s applicability in daily life based on readings taken from a healthy adult. Multiple devices, each of which contains a tri-axial accelerometer, a tri-axial gyroscope and a tri-axial magnetometer were attached to the dominant hand, wrist, upper arm and chest of 30 healthy participants and one stroke patient, who all performed the tasks ‘drinking’, ‘eating’ and ‘brushing hair’ in a standardized environment. To establish proof-of-principle, a prolonged daily life recording of 1 participant was used to identify the task ‘drinking’. The activities were identified using multi-array signal feature extraction and pattern recognition algorithms and 2D-convolution. The activities ‘drinking’, ‘eating’ and ‘brushing hair’ were unambiguously recognized in a sequence of recordings of multiple standardized daily activities in a healthy participant and in a stroke patient. It was also possible to identify a specific activity in a daily life recording. The long term aim is to use this method to a) identify arm-hand activities that someone performs during daily life, b) determine the quantity of activity execution, i.e. amount of use, and c) determine the quality of arm-hand skill performance. PMID:25734641

  13. Tracking Activities in Complex Settings Using Smart Environment Technologies

    PubMed Central

    Singla, Geetika; Cook, Diane J.; Schmitter-Edgecombe, Maureen

    2009-01-01

    The pervasive sensing technologies found in smart homes offer unprecedented opportunities for providing health monitoring and assistance to individuals experiencing difficulties living independently at home. A primary challenge that needs to be tackled to meet this need is the ability to recognize and track functional activities that people perform in their own homes and everyday settings. In this paper we look at approaches to perform real-time recognition of Activities of Daily Living. We enhance other related research efforts to develop approaches that are effective when activities are interrupted and interleaved. To evaluate the accuracy of our recognition algorithms we assess them using real data collected from participants performing activities in our on-campus smart apartment testbed. PMID:20019890

  14. Synthesis, crystal structure, DNA binding and photo-induced DNA cleavage activity of (S-methyl-L-cysteine)copper(II) complexes of heterocyclic bases.

    PubMed

    Patra, Ashis K; Nethaji, Munirathinam; Chakravarty, Akhil R

    2007-02-01

    Ternary S-methyl-L-cysteine (SMe-l-cys) copper(II) complexes [Cu(SMe-L-cys)(B)(H(2)O)](X) (1-4), where the heterocyclic base B is 2,2'-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2), dipyridoquinoxaline (dpq, 3) and dipyridophenazine (dppz, 4), and X is ClO(4)(-) (1-3) or NO(3)(-) (4), are prepared and their DNA binding and cleavage properties studied. Complexes 2 and 4 are structurally characterized by X-ray crystallography. Both the crystal structures show distorted square-pyramidal (4+1) CuN(3)O(2) coordination geometry of the complexes in which the N,O-donor S-methyl-L-cysteine and N,N-donor heterocyclic base bind at the basal plane with a water molecule as the axial ligand. In addition, the dppz structure shows the presence of a 1D-chain formed due to covalent linkage of the carboxylate oxygen atom belonging to another molecule at the elongated axial site. The crystal structures show chemically significant non-covalent interactions like hydrogen bonding involving the axial aqua ligand and pi-pi interactions between dppz ligands. The complexes display a d-d band in the range of 605-654 nm in aqueous dimethylformamide (DMF) solution (9:1 v/v). The redox active complexes show quasireversible cyclic voltammetric response near 0.1 V in DMF assignable to the Cu(II)/Cu(I) couple. The complexes show good binding affinity to calf thymus (CT) DNA giving the order: 4 (dppz)>3 (dpq)>2 (phen)>1 (bpy). The intrinsic binding constants, obtained from UV-visible spectroscopic studies, are 1.3x10(4) and 2.15 x 10(4) M(-1) for 3 and 4, respectively. Control DNA cleavage experiments using pUC19 supercoiled (SC) DNA and minor groove binder distamycin suggest major groove binding propensity for the dppz complex, while the phen and dpq complexes bind at the minor groove of DNA. Complexes 2-4 show DNA cleavage activity in dark in the presence of a reducing agent 3-mercaptopropionic acid (MPA) via a mechanistic pathway involving formation of hydroxyl radical as the reactive

  15. Oxygen activation with transition metal complexes in aqueous solution

    SciTech Connect

    Bakac, Andreja

    2010-04-12

    Coordination to transition-metal complexes changes both the thermodynamics and kinetics of oxygen reduction. Some of the intermediates (superoxo, hydroperoxo, and oxo species) are close analogues of organic oxygen-centered radicals and peroxides (ROO{sm_bullet}, ROOH, and RO{sm_bullet}). Metal-based intermediates are typically less reactive, but more persistent, than organic radicals, which makes the two types of intermediates similarly effective in their reactions with various substrates. The self-exchange rate constant for hydrogen-atom transfer for the couples Cr{sub aq}OO{sup 2+}/Cr{sub aq}OOH{sup 2+} and L{sup 1}(H{sub 2}O)RhOO{sup 2+}/L{sup 1}(H{sub 2}O)RhOOH{sup 2+} was estimated to be 10{sup 1 {+-} 1} M{sup -1} s{sup -1}. The use of this value in the simplified Marcus equation for the Cr{sub aq}O{sup 2+}/Cr{sub aq}OOH{sup 2+} cross reaction provided an upper limit k{sub CrO,CrOH} {le} 10{sup (-2{+-}1)} M{sup -1} s{sup -1} for Cr{sub aq}O{sup 2+}/Cr{sub aq}OH{sup 2+} self-exchange. Even though superoxo complexes react very slowly in bimolecular self-reactions, extremely fast cross reactions with organic counterparts, i.e., acylperoxyl radicals, have been observed. Many of the intermediates generated by the interaction of O{sub 2} with reduced metal complexes can also be accessed by alternative routes, both thermal and photochemical.

  16. H2-assisted ternary recombination of H3+ with electrons at 300 K

    NASA Astrophysics Data System (ADS)

    Dohnal, Petr; Rubovič, Peter; Kálosi, Ábel; Hejduk, Michal; Plašil, Radek; Johnsen, Rainer; Glosík, Juraj

    2014-10-01

    Stationary afterglow measurements in conjunction with near-infrared absorption spectroscopy show that the recombination of the H3+ ion with electrons in ionized gas mixtures of He, Ar, and H2 at 300 K is strongly enhanced by neutral helium and by molecular hydrogen. The H2-assisted ternary recombination coefficient KH2=(8.7±1.5)×10-23cm6s-1 substantially exceeds the value measured for H3+ in ambient helium (KHe˜10-25cm6s-1) or predicted by the generally accepted classical theory of Bates and Khare (˜10-27cm6s-1) for atomic ions. Because of the extremely large value of KH2 in a hydrogen plasma the ternary recombination dominates over binary recombination already at pressures above 3 Pa. This can have consequences in plasma physics, astrophysics, recombination pumped lasers, plasma spectroscopy, plasmatic technologies, etc. The ternary processes provide a plausible explanation for the discrepancies between many earlier experimental results on H3+ recombination. The observation that the ternary process saturates at high He and H2 densities suggests that recombination proceeds by a two-step process: formation of a long-lived complex [with a rate coefficient αF=(1.5±0.1)×10-7cm3s-1] followed by collisional stabilization.

  17. Diorganotin Complexes of a Thiosemicarbazone, Synthesis: Properties, X-Ray Crystal Structure, and Antiproliferative Activity of Diorganotin Complexes

    PubMed Central

    Wiecek, Joanna; Kovala-Demertzi, Dimitra; Ciunik, Zbigniew; Zervou, Maria; Demertzis, Mavroudis A.

    2010-01-01

    The synthesis and spectral characterization of novel diorganotin complexes with 3-hydroxypyridine-2-carbaldehyde thiosemicarbazone, H2L(1), [SnMe2(L)] (2), [SnBu2(L)] (3), and [SnPh2(L)] (4) are reported. The single-crystal X-ray structure of complex [SnPh2(L)(DMSO)] (5) shows that the ligand is doubly deprotonated and is coordinated as tridentate ligand. The six coordination number is completed by two carbon atoms of phenyl groups. There are two similar monomers 5a (Sn1) and 5b (Sn51) in the asymmetric unit. The monomers 5a and 5b are linked through intermolecular hydrogen bonds of N–H–O and C–H–S type. C–H → π, intermolecular interactions, intra- and intermolecular hydrogen bonds stabilize this structure and leads to aggregation and a supramolecular assembly. The IR and NMR (1H, 13C and 119Sn) spectroscopic data of the complexes are reported. The in vitro cytotoxic activity has been evaluated against the cells of three human cancer cell lines: MCF-7 (human breast cancer cell line), T-24 (bladder cancer cell line), A-549 (nonsmall cell lung carcinoma) and a mouse L-929 (a fibroblast-like cell line cloned from strain L). Compounds 1, 3, and 4 were found active against all four cell lines. Selectivity was observed for complexes 3 and 4 which were found especially active against MCF-7 and T-24 cancer cell lines. PMID:20689713

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

    PubMed

    Bermudez, Dieldrich S; Gray, Leon E; Wilson, Vickie S

    2010-08-01

    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. However, few studies have addressed how xenoestrogens interact with endogenous estrogens. The current study was designed to characterize the individual dose-response curves of estradiol-17beta (E(2)), bisphenol A (BPA), tetrabromo-bisphenol A (TBBPA), and bisphenol AF (BPAF, 4,4'-hexafluoroisopropylidene diphenol) on estrogen-dependent luciferase expression in T47D-KBluc cells and to determine how binary (8 x 8 factorial) and ternary (4 x 4 x 4 factorial) mixtures of an endogenous estrogen (E(2)) interact with BPA and/or BPAF. Log EC(50) and hillslope values with SEs, respectively, for individual compounds were as follows: E(2), -12.10M +/- 0.06071, 0.7702 +/- 0.1739; BPA, -6.679M +/- 0.08505, 1.194 +/- 0.2137; and BPAF, -7.648M +/- 0.05527, 1.273 +/- 0.1739. TBBPA was not evaluated in mixture studies because of its minimally estrogenic response at 3 x10(-5)M and elicited cytotoxicity at higher concentrations. Both the binary mixtures of E(2) with BPA and BPAF and the ternary mixture of E(2), BPA, and BPAF behaved in an additive manner. For binary mixtures, as E(2) concentration increased, higher concentrations of BPA and BPAF were necessary to induce a significant increase in the estrogenic response. Understanding the behavior of mixture interactions of xenoestrogens, like BPA and BPAF, with endogenous estrogens will allow a better assessment of the potential risk associated with exposure to these chemicals, individually or as mixtures. PMID:20498000

  19. Modeling the Interaction of Binary and Ternary Mixtures of Estradiol with Bisphenol A and Bisphenol AF in an In Vitro Estrogen-Mediated Transcriptional Activation Assay (T47D-KBluc)

    PubMed Central

    Bermudez, Dieldrich S.; Gray, Leon E.; Wilson, Vickie S.

    2010-01-01

    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. However, few studies have addressed how xenoestrogens interact with endogenous estrogens. The current study was designed to characterize the individual dose-response curves of estradiol-17β (E2), bisphenol A (BPA), tetrabromo-bisphenol A (TBBPA), and bisphenol AF (BPAF, 4,4'-hexafluoroisopropylidene diphenol) on estrogen-dependent luciferase expression in T47D-KBluc cells and to determine how binary (8 × 8 factorial) and ternary (4 × 4 × 4 factorial) mixtures of an endogenous estrogen (E2) interact with BPA and/or BPAF. Log EC50 and hillslope values with SEs, respectively, for individual compounds were as follows: E2, −12.10M ± 0.06071, 0.7702 ± 0.1739; BPA, −6.679M ± 0.08505, 1.194 ± 0.2137; and BPAF, −7.648M ± 0.05527, 1.273 ± 0.1739. TBBPA was not evaluated in mixture studies because of its minimally estrogenic response at 3 ×10−5M and elicited cytotoxicity at higher concentrations. Both the binary mixtures of E2 with BPA and BPAF and the ternary mixture of E2, BPA, and BPAF behaved in an additive manner. For binary mixtures, as E2 concentration increased, higher concentrations of BPA and BPAF were necessary to induce a significant increase in the estrogenic response. Understanding the behavior of mixture interactions of xenoestrogens, like BPA and BPAF, with endogenous estrogens will allow a better assessment of the potential risk associated with exposure to these chemicals, individually or as mixtures. PMID:20498000

  20. Activation of isocyanate ligands in Ru25+ complexes

    NASA Astrophysics Data System (ADS)

    Barral, M. Carmen; Herrero, Santiago; Jiménez-Aparicio, Reyes; Priego, José L.; Torres, M. Rosario; Urbanos, Francisco A.

    2008-11-01

    The reaction of [Ru 2(O 2CMe)(DPhF) 3(H 2O)]BF 4 · 0.5CH 2Cl 2 (DphF dbnd N, N'-diphenylformidinate) with sodium cyanate leads to the substitution of the H 2O ligand giving Ru 2(NCO)(O 2CMe)(DPhF) 3 ( 1). In contrast, in the similar reaction of Ru 2Cl 2(DPhF) 3 with NaOCN one of the cyanate groups undergoes the addition of a MeOH molecule leading to the carbamate complex Ru 2(NCO)(NH(O)COMe)(DPhF) 3 ( 2). The spectroscopic properties of 1 and 2 are studied. Both complexes are paramagnetic showing the presence of three unpaired electrons with an important zero-field splitting and a small intermolecular antiferromagnetic interaction. The crystal structures of 1 · 3CHCl 3 and 2 · C 7H 8 · 0.5MeOH are also reported. Compound 2 represents the first example of a ruthenium paddlewheel compound with a carbamate ligand.

  1. Interaction of drug based copper(II) complexes with Herring Sperm DNA and their biological activities

    NASA Astrophysics Data System (ADS)

    Patel, Mohan N.; Patel, Chintan R.; Joshi, Hardik N.

    2012-11-01

    Square pyramidal Cu(II) complexes with NS donor ligand and ciprofloxacin have been synthesized and characterized using analytical and spectral techniques. The synthesized complexes have been tested for their antimicrobial activity using double dilution technique in terms of minimum inhibitory concentration (MIC) and colony forming unit (CFU). The DNA binding ability of the complexes with Sperm Herring DNA has been performed using absorption titration and viscosity measurement. The nuclease activity of complexes with plasmid DNA (pUC19) has been carried out using agarose gel electrophoresis technique. Synthesized complexes have been tested for their SOD mimic activity using NBT/NADH/PMS system. The cytotoxic properties of metal complexes have been evaluated using brine shrimp lethality bioassay.

  2. Interaction of drug based copper(II) complexes with Herring Sperm DNA and their biological activities.

    PubMed

    Patel, Mohan N; Patel, Chintan R; Joshi, Hardik N

    2012-11-01

    Square pyramidal Cu(II) complexes with NS donor ligand and ciprofloxacin have been synthesized and characterized using analytical and spectral techniques. The synthesized complexes have been tested for their antimicrobial activity using double dilution technique in terms of minimum inhibitory concentration (MIC) and colony forming unit (CFU). The DNA binding ability of the complexes with Sperm Herring DNA has been performed using absorption titration and viscosity measurement. The nuclease activity of complexes with plasmid DNA (pUC19) has been carried out using agarose gel electrophoresis technique. Synthesized complexes have been tested for their SOD mimic activity using NBT/NADH/PMS system. The cytotoxic properties of metal complexes have been evaluated using brine shrimp lethality bioassay. PMID:22750339

  3. Plasmonic spectral tunability of conductive ternary nitrides

    NASA Astrophysics Data System (ADS)

    Kassavetis, S.; Bellas, D. V.; Abadias, G.; Lidorikis, E.; Patsalas, P.

    2016-06-01

    Conductive binary transition metal nitrides, such as TiN and ZrN, have emerged as a category of promising alternative plasmonic materials. In this work, we show that ternary transition metal nitrides such as TixTa1-xN, TixZr1-xN, TixAl1-xN, and ZrxTa1-xN share the important plasmonic features with their binary counterparts, while having the additional asset of the exceptional spectral tunability in the entire visible (400-700 nm) and UVA (315-400 nm) spectral ranges depending on their net valence electrons. In particular, we demonstrate that such ternary nitrides can exhibit maximum field enhancement factors comparable with gold in the aforementioned broadband range. We also critically evaluate the structural features that affect the quality factor of the plasmon resonance and we provide rules of thumb for the selection and growth of materials for nitride plasmonics.

  4. Modulated Binary-Ternary Dual Semiconductor Heterostructures.

    PubMed

    Prusty, Gyanaranjan; Guria, Amit K; Mondal, Indranil; Dutta, Anirban; Pal, Ujjwal; Pradhan, Narayan

    2016-02-18

    A generic modular synthetic strategy for the fabrication of a series of binary-ternary group II-VI and group I-III-VI coupled semiconductor nano-heterostructures is reported. Using Ag2 Se nanocrystals first as a catalyst and then as sacrificial seeds, four dual semiconductor heterostructures were designed with similar shapes: CdSe-AgInSe2 , CdSe-AgGaSe2 , ZnSe-AgInSe2 , and ZnSe-AgGaSe2 . Among these, dispersive type-II heterostructures are further explored for photocatalytic hydrogen evolution from water and these are observed to be superior catalysts than the binary or ternary semi-conductors. Details of the chemistry of this modular synthesis have been studied and the photophysical processes involved in catalysis are investigated. PMID:26800297

  5. Soluble complement complex C5b-9 promotes microglia activation.

    PubMed

    Yang, Chao; Yang, Li; Liu, Yong

    2014-02-15

    Soluble C5b-9 has been described as a pro-inflammatory mediator that triggers cell activation rather than inducing cell death. Microglia is the most important immune cell involved in inflammatory response in the CNS. Although microglia activation induced by various stimuli has been well characterized, the role of C5b-9 in microglia has not been well studied. In the current experiment, we utilized assembled functional C5b-9 to treat microglia and analyzed the function. We found that soluble C5b-9 could promote microglia activation by up-regulation of costimulatory molecules and increase cytokine secretion. Our results suggested that soluble C5b-9 possessed immunoregulatory potential on microglia. PMID:24434076

  6. Ternary rare earth-lanthanide sulfides

    DOEpatents

    Takeshita, Takuo; Gschneidner, Jr., Karl A.; Beaudry, Bernard J.

    1987-01-06

    A new ternary rare earth sulfur compound having the formula: La.sub.3-x M.sub.x S.sub.4 where M is a rare earth element selected from the group europium, samarium and ytterbium and x=0.15 to 0.8. The compound has good high-temperature thermoelectric properties and exhibits long-term structural stability up to 1000.degree. C.

  7. Brains and Brawn: Complex Motor Activities to Maximize Cognitive Enhancement

    ERIC Educational Resources Information Center

    Moreau, David

    2015-01-01

    The target articles in this special issue address the timely question of embodied cognition in the classroom, and in particular the potential of this approach to facilitate learning in children. The interest for motor activities within settings that typically give little space to nontraditional content is proof of a shift from a Cartesian…

  8. Cognitive Activities in Complex Science Text and Diagrams

    ERIC Educational Resources Information Center

    Cromley, Jennifer G.; Snyder-Hogan, Lindsey E.; Luciw-Dubas, Ulana A.

    2010-01-01

    Ainsworth's (2006) DeFT framework posits that different representations may lead learners to use different strategies. We wanted to investigate whether students use different strategies, and more broadly, different cognitive activities in diagrams vs. in running text. In order to do so, we collected think-aloud protocol and other measures from 91…

  9. Antimycobacterial activity of bacteriocins and their complexes with liposomes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacteriocins (Bcn) are natural peptides that are secreted by taxonomically distinct bacteria which exert bactericidal activity against other bacterial species. Their capacity to inhibit growth of virulent Mycobacterium tuberculosis H37Rv was evaluated in this study. Five Bcn were purified from sel...

  10. Dynamic workflow model for complex activity in intensive care unit.

    PubMed

    Bricon-Souf, N; Renard, J M; Beuscart, R

    1998-01-01

    Cooperation is very important in Medical care, especially in the Intensive Care Unit (ICU) where the difficulties increase which is due to the urgency of the work. Workflow systems are considered as well adapted to modelize productive work in business process. We aim at introducing this approach in the Health Care domain. We have proposed a conversation-based Workflow in order to modelize the therapeutics plan in the ICU [1]. But in such a complex field, the flexibility of the workflow system is essential for the system to be usable. In this paper, we focus on the main points used to increase the dynamicity. We report on affecting roles, highlighting information, and controlling the system We propose some solutions and describe our prototype in the ICU. PMID:10384452

  11. B-Ring-Aryl Substituted Luotonin A Analogues with a New Binding Mode to the Topoisomerase 1-DNA Complex Show Enhanced Cytotoxic Activity

    PubMed Central

    González-Ruiz, Víctor; Pascua, Irene; Fernández-Marcelo, Tamara; Ribelles, Pascual; Bianchini, Giulia; Sridharan, Vellaisamy; Iniesta, Pilar; Ramos, M. Teresa; Olives, Ana I.; Martín, M. Antonia; Menéndez, J. Carlos

    2014-01-01

    Topoisomerase 1 inhibition is an important strategy in targeted cancer chemotherapy. The drugs currently in use acting on this enzyme belong to the family of the camptothecins, and suffer severe limitations because of their low stability, which is associated with the hydrolysis of the δ-lactone moiety in their E ring. Luotonin A is a natural camptothecin analogue that lacks this functional group and therefore shows a much-improved stability, but at the cost of a lower activity. Therefore, the development of luotonin A analogues with an increased potency is important for progress in this area. In the present paper, a small library of luotonin A analogues modified at their A and B rings was generated by cerium(IV) ammonium nitrate-catalyzed Friedländer reactions. All analogues showed an activity similar or higher than the natural luotonin A in terms of topoisomerase 1 inhibition and some compounds had an activity comparable to that of camptothecin. Furthermore, most compounds showed a better activity than luotonin A in cell cytotoxicity assays. In order to rationalize these results, the first docking studies of luotonin-topoisomerase 1-DNA ternary complexes were undertaken. Most compounds bound in a manner similar to luotonin A and to standard topoisomerase poisons such as topotecan but, interestingly, the two most promising analogues, bearing a 3,5-dimethylphenyl substituent at ring B, docked in a different orientation. This binding mode allows the hydrophobic moiety to be shielded from the aqueous environment by being buried between the deoxyribose belonging to the G(+1) guanine and Arg364 in the scissile strand and the surface of the protein and a hydrogen bond between the D-ring carbonyl and the basic amino acid. The discovery of this new binding mode and its associated higher inhibitory potency is a significant advance in the design of new topoisomerase 1 inhibitors. PMID:24830682

  12. Synthesis, characterization and investigation of antioxidant activity of cobalt quercetin complex

    NASA Astrophysics Data System (ADS)

    Birjees Bukhari, S.; Memon, Shahabuddin; Mahroof Tahir, M.; Bhanger, M. I.

    2008-12-01

    This article describes a novel synthesis of cobalt and quercetin·2H 2O complex in methanol, characterized by using elemental analysis, UV-visible, 1H NMR, TGA, DSC and IR spectrometric techniques. The formation of complex is deduced from the UV-visible spectra which shows that the successive formation of cobalt-quercetin complex occurs in a ratio of 2:1 (metal/ligand) stoichiometrically. The antioxidant activity of the complex was evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. In this work, we have shown that the metal complexed flavonoids are much more effective free radical scavengers than the free flavonoids.

  13. Predicting Water Activity for Complex Wastes with Solvation Cluster Equilibria (SCE) - 12042

    SciTech Connect

    Agnew, S.F.; Reynolds, J.G.; Johnston, C.T.

    2012-07-01

    Predicting an electrolyte mixture's water activity, i.e. the ratio of water vapor pressure over a solution with that of pure water, in principle reveals both boiling point and solubilities for that mixture. Better predictions of these properties helps support the ongoing missions to concentrate complex nuclear waste mixtures in order to conserve tank space and improved predictions of water activity will help. A new approach for predicting water activity, the solvation cluster equilibria (SCE) model, uses pure electrolyte water activities to predict water activity for a complex mixture of those electrolytes. An SCE function based on electrolyte hydration free energy and a standard Debye- Hueckel (DH) charge compression fits each pure electrolyte's water activity with three parameters. Given these pure electrolyte water activities, the SCE predicts any mixture water activity over a large range of concentration with an additional parameter for each mixture vector, the multinarity. In contrast to ionic strength, which scales with concentration, multinarity is related to the relative proportion of electrolytes in a mixture and can either increase or decrease the water activity prediction over a broad range of concentration for that mixture. The SCE model predicts water activity for complex electrolyte mixtures based on the water activities of pure electrolytes. Three parameter SCE functions fit the water activities of pure electrolytes and along with a single multinarity parameter for each mixture vector then predict the mixture water activity. Predictions of water activity can in principle predict solution electrolyte activity and this relationship will be explored in the future. Predicting electrolyte activities for complex mixtures provides a means of determining solubilities for each electrolyte. Although there are a number of reports [9, 10, 11] of water activity models for pure and binary mixtures of electrolytes, none of them compare measured versus calculated

  14. Dioxygen activation in the Cu-amyloid β complex.

    PubMed

    Mirats, Andrea; Alí-Torres, Jorge; Rodríguez-Santiago, Luis; Sodupe, Mariona; La Penna, Giovanni

    2015-11-01

    We investigate, by means of density-functional theory, the binding of dioxygen to Cu(I)-amyloid β (Aβ), one of the first steps in the oxidation of ascorbate by dioxygen. Cu, Aβ, ascorbate and dioxygen are all present in the synapse during neurodegeneration, when the above species can trigger an irreversible oxidative stress inducing the eventual death of neurons. The binding of dioxygen to Cu(I) is possible and its role in dioxygen activation of Cu ligands and of residues in the first coordination sphere is described in atomic detail. Dioxygen is activated when a micro-environment suitable for a square-planar Cu(2+) coordination is present and a negatively charged group like Asp 1 carboxylate takes part in the Cu coordination anti to O2. PMID:26427541

  15. Case study of a complex active-region filament eruption

    NASA Astrophysics Data System (ADS)

    Yan, X. L.; Qu, Z. Q.; Kong, D. F.; Deng, L. H.; Xue, Z. K.

    2013-09-01

    Context. We investigated a solar active-region filament eruption associated with a C6.6 class flare and a coronal mass ejection (CME) in NOAA active region 08858 on 2000 February 9. Aims: We aim to better understand the relationship between filament eruptions and the associated flares and CMEs. Methods: Using BBSO, SOHO/EIT, and TRACE observational data, we analyzed the process of the active-region filament eruption in the chromosphere and the corona. Using the SOHO/MDI magnetograms, we investigated the change of the magnetic fields in the photosphere. Using the GOES soft X-ray flux and the SOHO/LASCO images, we identified the flare and CME, which were associated with this active-region filament eruption. Results: The brightenings in the chromosphere are a precursor of the filament expansion. The eruption itself can be divided into four phases: In the initial phase, the intertwined bright and dark strands of the filament expand. Then, the bright strands are divided into three parts with different expansion velocity. Next, the erupting filament-carrying flux rope expands rapidly and combines with the lower part of the expanding bright strands. Finally, the filament erupts accompanied by other dark strands overlying the filament.The overlying magnetic loops and the expansion of the filament strands can change the direction of the eruption. Conclusions: The time delay between the velocity peaks of the filament and that of the two parts of the bright strands clearly demonstrates that the breakup of the bright loops tying on the filament into individual strands is important for its eruption. The eruption is a collection of multiple processes that are physically coupled rather than a single process.

  16. Reconstitution of active and stoichiometric multisubunit lysine acetyltransferase complexes in insect cells.

    PubMed

    Yan, Kezhi; Wu, Chao-Jung; Pelletier, Nadine; Yang, Xiang-Jiao

    2012-01-01

    Protein lysine acetyltransferases (KATs) catalyze acetylation of the ε-amino group on a specific lysine residue, and this posttranslational modification is important for regulating the function and activities of thousands of proteins in diverse organisms from bacteria to humans. Interestingly, many known KATs exist in multisubunit complexes and complex formation is important for their proper structure, function, and regulation. Thus, it is necessary to reconstitute enzymatically active complexes for studying the relationship between subunits and determining structures of the complexes. Due to inherent limitations of bacterial and mammalian expression systems, baculovirus-mediated protein expression in insect cells has proven useful for assembling such multisubunit complexes. Related to this, we have adopted such an approach for reconstituting active tetrameric complexes of monocytic leukemia zinc (MOZ, finger protein, recently renamed MYST3 or KAT6A) and MOZ-related factor (MORF, also known as MYST4 or KAT6B), two KATs directly linked to development of leukemia and self-renewal of stem cells. Herein, we use these complexes as examples to describe the related procedures. Similar methods have been used for reconstituting active complexes of histone deacetylases, lysine demethylases, and ubiquitin ligases, so this simple approach can be adapted for molecular dissection of various multisubunit complexes. PMID:22113293

  17. Effects of humic acid-metal complexes on hepatic carnitine palmitoyltransferase, carnitine acetyltransferase and catalase activities

    SciTech Connect

    Fungjou Lu; Youngshin Chen . Dept. of Biochemistry); Tienshang Huang . Dept. of Medicine)

    1994-03-01

    A significant increase in activities of hepatic carnitine palmitoyltransferase and carnitine acetyltransferase was observed in male Balb/c mice intraperitoneally injected for 40 d with 0.125 mg/0.1 ml/d humic acid-metal complexes. Among these complexes, the humic acid-As complex was relatively effective, whereas humic acid-25 metal complex was more effective, and humic acid-26 metal complex was most effective. However, humic acid or metal mixtures, or metal such as As alone, was not effective. Humic acid-metal complexes also significantly decreased hepatic catalase activity. A marked decrease of 60-kDa polypeptide in liver cytoplasm was also observed on SDS-polyacrylamide gel electrophoresis after the mice had been injected with the complexes. Morphological analysis of a histopathological biopsy of such treated mice revealed several changes in hepatocytes, including focal necrosis and cell infiltration, mild fatty changes, reactive nuclei, and hypertrophy. Humic acid-metal complexes affect activities of metabolic enzymes of fatty acids, and this results in accumulation of hydrogen peroxide and increase of the lipid peroxidation. The products of lipid peroxidation may be responsible for liver damage and possible carcinogenesis. Previous studies in this laboratory had shown that humic acid-metal complex altered the coagulation system and that humic acid, per se, caused vasculopathy. Therefore, humic acid-metal complexes may be main causal factors of not only so-called blackfoot disease, but also the liver cancer prevailing on the southwestern coast of Taiwan.

  18. The Crystal Structure of a Ternary Complex of Betaine Aldehyde Dehydrogenase from Pseudomonas aeruginosa Provides New Insight Into the Reaction Mechansim and Shows A Novel Binding Mode of the 2'-Phosphate of NADP+ and A Novel Cation Binding Site

    SciTech Connect

    Gonzalez-Segura, L.; Rudino-Pinera, E; Munoz-Clares, R; Horjales, E

    2009-01-01

    In the human pathogen Pseudomonas aeruginosa, the NAD(P)+-dependent betaine aldehyde dehydrogenase (PaBADH) may play the dual role of assimilating carbon and nitrogen from choline or choline precursors-abundant at infection sites-and producing glycine betaine and NADPH, potentially protective against the high-osmolarity and oxidative stresses prevalent in the infected tissues. Disruption of the PaBADH gene negatively affects the growth of bacteria, suggesting that this enzyme could be a target for antibiotic design. PaBADH is one of the few ALDHs that efficiently use NADP+ and one of the even fewer that require K+ ions for stability. Crystals of PaBADH were obtained under aerobic conditions in the presence of 2-mercaptoethanol, glycerol, NADP+ and K+ ions. The three-dimensional structure was determined at 2.1-A resolution. The catalytic cysteine (C286, corresponding to C302 of ALDH2) is oxidized to sulfenic acid or forms a mixed disulfide with 2-mercaptoethanol. The glutamyl residue involved in the deacylation step (E252, corresponding to E268 of ALDH2) is in two conformations, suggesting a proton relay system formed by two well-conserved residues (E464 and K162, corresponding to E476 and K178, respectively, of ALDH2) that connects E252 with the bulk water. In some active sites, a bound glycerol molecule mimics the thiohemiacetal intermediate; its hydroxyl oxygen is hydrogen bonded to the nitrogen of the amide groups of the side chain of the conserved N153 (N169 of ALDH2) and those of the main chain of C286, which form the 'oxyanion hole.' The nicotinamide moiety of the nucleotide is not observed in the crystal, and the adenine moiety binds in the usual way. A salt bridge between E179 (E195 of ALDH2) and R40 (E53 of ALDH2) moves the carboxylate group of the former away from the 2?-phosphate of the NADP+, thus avoiding steric clashes and/or electrostatic repulsion between the two groups. Finally, the crystal shows two K+ binding sites per subunit. One is in an

  19. Dynamic workflow model for complex activity in intensive care unit.

    PubMed

    Bricon-Souf, N; Renard, J M; Beuscart, R

    1999-01-01

    Co-operation is very important in Medical care, especially in the Intensive Care Unit (ICU) where the difficulties increase which is due to the urgency of the work. Workflow systems are considered as well adapted to modelize productive work in business process. We aim at introducing this approach in the Health Care domain. We have proposed a conversation-based workflow in order to modelize the therapeutics plan in the ICU [1]. But in such a complex field, the flexibility of the workflow system is essential for the system to be usable. We have concentrated on three main points usually proposed in the workflow models, suffering from a lack of dynamicity: static links between roles and actors, global notification of information changes, lack of human control on the system. In this paper, we focus on the main points used to increase the dynamicity. We report on affecting roles, highlighting information, and controlling the system. We propose some solutions and describe our prototype in the ICU. PMID:10193884

  20. Active listening for spatial orientation in a complex auditory scene.

    PubMed

    Moss, Cynthia F; Bohn, Kari; Gilkenson, Hannah; Surlykke, Annemarie

    2006-04-01

    To successfully negotiate a complex environment, an animal must control the timing of motor behaviors in coordination with dynamic sensory information. Here, we report on adaptive temporal control of vocal-motor behavior in an echolocating bat, Eptesicus fuscus, as it captured tethered insects close to background vegetation. Recordings of the bat's sonar vocalizations were synchronized with high-speed video images that were used to reconstruct the bat's three-dimensional flight path and the positions of target and vegetation. When the bat encountered the difficult task of taking insects as close as 10-20 cm from the vegetation, its behavior changed significantly from that under open room conditions. Its success rate decreased by about 50%, its time to initiate interception increased by a factor of ten, and its high repetition rate "terminal buzz