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Sample records for acid side groups

  1. [New approach to the study of interaction of amino acid side groups with aryl azides].

    PubMed

    Knorre, D G; Bichenkova, E V; Koval', V V; Alekseev, P V; Knorre, V D; Nordhoff, E; Godovikova, T S

    1998-09-01

    A new approach to the study of the interaction of amino acid side chains with photoreactive aryl azides was proposed. This approach was based on the drawing together of the reacting groups by the attachment of the reacting compounds to complementary oligonucleotides. Cystamine, histamine, and 1,6-hexamethylenediamine mimicking the cystine, histidine, and lysine residues, respectively, were attached to the 3'-terminal phosphate of the oligonucleotide GGTATCp through a phosphamide bond and used as the targets for photomodification. Derivatives of the oligonucleotide pGATACCAA with the fragment N3C6H4NH- attached directly to its 5'-end by a phosphamide bond or through the spacer -(CH2)nNH- (where n is 2, 4, and 6) were used as photoreagents. Their derivatives containing the same spacer and the N3C6F4CO-NH(CH2)3NH- or 2-N3,5-NO2-C6H3CO-NH(CH2)3NH- residues were also used. The duplexes were photomodified by irradiation with 300-350 nm wavelength light. The maximal yields of the photo-cross-linking were from 22 to 68%. The reagents containing p-azidoaniline residue were found to be the most effective toward the targets. The maximum yields of the photomodification products modeling the side chains of cysteine and lysine were found to vary from 40 to 67% and to depend on the length and the structure of the spacers used. The duplex with the target bearing the imidazole residue (the histidine model) manifested a yield decreased to 25%. This fact was in a good agreement with the data of computer modeling that indicated an unfavorable mutual displacement of the imidazole residue and the photoreactive group.

  2. Local softness, softness dipole, and polarizabilities of functional groups: Application to the side chains of the 20 amino acids

    NASA Astrophysics Data System (ADS)

    Krishtal, Alisa; Senet, Patrick; Van Alsenoy, Christian

    2009-07-01

    The values of molecular polarizabilities and softnesses of the 20 amino acids were computed ab initio (MP2). By using the iterative Hirshfeld scheme to partition the molecular electronic properties, we demonstrate that the values of the softness of the side chain of the 20 amino acids are clustered in groups reflecting their biochemical classification, namely: aliphatic, basic, acidic, sulfur containing, and aromatic amino acids. The present findings are in agreement with previous results using different approximations and partitioning schemes [P. Senet and F. Aparicio, J. Chem. Phys. 126, 145105 (2007)]. In addition, we show that the polarizability of the side chain of an amino acid depends mainly on its number of electrons (reflecting its size) and consequently cannot be used to cluster the amino acids in different biochemical groups, in contrast to the local softness. Our results also demonstrate that the global softness is not simply proportional to the global polarizability in disagreement with the intuition that "a softer moiety is also more polarizable." Amino acids with the same softness may have a polarizability differing by a factor as large as 1.7. This discrepancy can be understood from first principles as we show that the molecular polarizability depends on a "softness dipole vector" and not simply on the global softness.

  3. The darker side of groups.

    PubMed

    Thomas, Mike; Hynes, Celia

    2007-05-01

    This paper examines the role of group interaction in the workplace and the impact of anxiety on group cohesion. It takes a psychoanalytical perspective and highlights how early learning within a familial setting influences later attitudes and behaviour at work. In particular the article focuses on the signs of negative group anxiety and how the manager can recognise anti-group culture. By recognising the negative signs the leader can also come to understand how the anti-group develops and thereby prevent the resulting disruptive behaviour. In some instances the perception of anti-group feelings and behaviour can also be altered so that the team leader can reach a positive outcome for the group dynamic and resultant team cohesion and collaboration.

  4. [Side Effects of Occupational Group Therapy].

    PubMed

    Flöge, B; Fay, D; Jöbges, M; Linden, M; Muschalla, B

    2016-12-01

    Background: Occupational therapy is an important co-therapy in psychiatric therapy. It is a common belief that no risks are associated with occupational therapy. Negative effects caused by group therapy, especially occupational therapy, have not been in the focus of research yet. In this study we want to illustrate possible types and intensities of group side effects through occupational therapy. Patients and Methods: Patients of an inpatient rehabilitation facility filled out the Adverse Treatment Reaction Group Checklist. The checklist contains 47 items divided in six dimensions: group size, content, group participants, group outcome and global. The self-rating used a 5-point likert scale (0 = not at all; 4 = very much, extremely stressful) and gives information about types and intensities of the side effects. Results: 88.9 % of 45 patients reported negative effects of occupational group therapy. 28.9 % of the patients rated the side effect as at least severe. Discussion: Occupational therapy is associated with side effects as every other group therapy. Possible side effects caused by group therapy should be considered while planning and implementing occupational therapy.

  5. Influence of Side-Groups on Thermotropic Behavior of Polyorganophosphazenes

    DTIC Science & Technology

    1988-07-08

    Rather, these correlations depict how steric interactions associated with side group chemistry and dimensions influence the conformation of side groups ...OFFICE OF NAVAL RESEARCH Contract N00014-85-K-0358 Technical Report No. 8 INFLUENCE OF SIDE- GROUPS ON . j * ’A..,.. -Ti-ERMOTROPIC BEHAVIOR OF...5..i. * I L OFFICE OF NAVAL RESEARCH Contract N00014-85-K-0358 Technical Report No. 8 INFLUENCE OF SIDE- GROUPS ON THERMOTROPIC BEHAVIOR OF

  6. The Shadow Side of Regressive Groups.

    ERIC Educational Resources Information Center

    McClure, Bud A.

    1994-01-01

    Contends that inability of groups to address conflict, encourage dissenting views, and face their negative characteristics can result in destructive behavior toward others that remains largely outside awareness of individual members. Examines regressive group characteristics; behavior of United States during Persian Gulf War is used to highlight…

  7. 2. ACID STORAGE SHED, FRONT AND RIGHT SIDES, LOOKING SOUTHWEST. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. ACID STORAGE SHED, FRONT AND RIGHT SIDES, LOOKING SOUTHWEST. - NIKE Missile Base C-84, Acid Storage Shed, North of launch area, northwest of earthen berm of Acid Fueling Station, Barrington, Cook County, IL

  8. Nanoparticles made of multi-block copolymer of lactic acid and ethylene glycol containing periodic side-chain carboxyl groups for oral delivery of cyclosporine A

    PubMed Central

    Ankola, D. D.; Battisti, A.; Solaro, R.; Kumar, M. N. V. Ravi

    2010-01-01

    The purpose of this study was to evaluate the potential of new carboxylated multi-block copolymer of lactic acid and ethylene glycol (EL14) for nanoparticle (NP) formation and their ability to deliver high molecular weight hydrophobic drug—cyclosporine A (CsA). CsA-loaded EL14 NPs were compared with traditional poly(lactide-co-glycolide) (PLGA) NPs, both prepared by emulsion–diffusion–evaporation process. On the one hand, the increase in drug payload from 10 to 30 per cent for EL14 NPs showed no difference in particle size, however the entrapment efficiency tends to decrease from 50 to 43 per cent; on the other hand, the more hydrophobic PLGA showed an increasing trend in entrapment efficiency from 20 to 62 per cent with increasing particle size. Over 90 per cent of CsA was released in vitro from both the nanoparticulates; however, the release was much slower in the case of more hydrophobic PLGA. On in vivo evaluation in rats, the NPs made of EL14 showed a higher Cmax, a faster Tmax and enhanced tissue levels to that of PLGA that are crucial for CsA's activity and toxicity; however, the overall bioavailability of the nanoparticulates was similar and higher than Neoral. Together these data demonstrate the feasibility of NPs made of low molecular weight, hydrophilic polymer EL14 for efficient delivery of CsA. PMID:20504806

  9. 129. VIEW OF WEST SIDE OF ACID TRUCK ROOM (113), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    129. VIEW OF WEST SIDE OF ACID TRUCK ROOM (113), LSB (BLDG. 770). BAY DOOR OPENS TO FUEL APRON ON WEST SIDE. BRICK FLOOR DATES FROM AGENA PERIOD WHEN ACID WAS STORED IN THE ROOM. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  10. 25. SECOND FLOOR EAST SIDE APARTMENT KITCHEN INTERIOR SHOWING GROUP ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. SECOND FLOOR EAST SIDE APARTMENT KITCHEN INTERIOR SHOWING GROUP OF THREE 6-LIGHT WOOD-FRAME CASEMENT WINDOWS OVER THE SINK, AND OPEN DOORWAY TO TOP OF EXTERIOR STAIR LANDING AND WALKWAY AT REAR OF HOUSE. WALKWAY IS VISIBLE THROUGH KITCHEN WINDOWS. VIEW TO SOUTH. - Lee Vining Creek Hydroelectric System, Triplex Cottage, Lee Vining Creek, Lee Vining, Mono County, CA

  11. Strengths of hydrogen bonds involving phosphorylated amino acid side chains.

    PubMed

    Mandell, Daniel J; Chorny, Ilya; Groban, Eli S; Wong, Sergio E; Levine, Elisheva; Rapp, Chaya S; Jacobson, Matthew P

    2007-01-31

    Post-translational phosphorylation plays a key role in regulating protein function. Here, we provide a quantitative assessment of the relative strengths of hydrogen bonds involving phosphorylated amino acid side chains (pSer, pAsp) with several common donors (Arg, Lys, and backbone amide groups). We utilize multiple levels of theory, consisting of explicit solvent molecular dynamics, implicit solvent molecular mechanics, and quantum mechanics with a self-consistent reaction field treatment of solvent. Because the approximately 6 pKa of phosphate suggests that -1 and -2 charged species may coexist at physiological pH, hydrogen bonds involving both protonated and deprotonated phosphates for all donor-acceptor pairs are considered. Multiple bonding geometries for the charged-charged interactions are also considered. Arg is shown to be capable of substantially stronger salt bridges with phosphorylated side chains than Lys. A pSer hydrogen-bond acceptor tends to form more stable interactions than a pAsp acceptor. The effect of phosphate protonation state on the strengths of the hydrogen bonds is remarkably subtle, with a more pronounced effect on pAsp than on pSer.

  12. Order, Disorder and Stretching of a Smectic Elastomer with ‘side-on’ Mesogenic Side Groups

    SciTech Connect

    de Jeu, W.; Komp, A; Obraztsov, E; Ostrovskii, B; Finkelmann, H

    2009-01-01

    We report an X-ray study of the order in a 'side-on' smectic-A elastomer in which both the polymer backbone and the mesogenic side groups are, on average, parallel to the smectic layer normal. The present system shows in all phases locally correlated structures as evidenced by systematic diffuse scattering at small angles, attributed to the fluorinated end groups of the mesogens. The elastomer shows order of the smectic layers over a limited range in spite of the relatively low crosslink concentration (4%). Upon stretching along the layer normal we find a linear increase of the smectic layer period for small loading (elastic regime). These changes parallel the stress variation for the elastic part of the macroscopic stress-strain curve and saturate at larger strains. The attendant increase in the width of the X-ray peaks indicates a decrease of the average domain dimensions. In the plastic regime no distortion of the smectic monodomain structure or layer rotation is observed. Instead the stress is relieved by 'melting' of the layer structure giving rise to a nematic-like state with short-range layer correlations: at the final stage about four smectic layers.

  13. Electronic properties of amino acid side chains: quantum mechanics calculation of substituent effects

    PubMed Central

    Dwyer, Donard S

    2005-01-01

    Background Electronic properties of amino acid side chains such as inductive and field effects have not been characterized in any detail. Quantum mechanics (QM) calculations and fundamental equations that account for substituent effects may provide insight into these important properties. PM3 analysis of electron distribution and polarizability was used to derive quantitative scales that describe steric factors, inductive effects, resonance effects, and field effects of amino acid side chains. Results These studies revealed that: (1) different semiempirical QM methods yield similar results for the electronic effects of side chain groups, (2) polarizability, which reflects molecular deformability, represents steric factors in electronic terms, and (3) inductive effects contribute to the propensity of an amino acid for α-helices. Conclusion The data provide initial characterization of the substituent effects of amino acid side chains and suggest that these properties affect electron density along the peptide backbone. PMID:16078995

  14. Aggregation Behavior of Dendritic Side Group Luminescent Polymers

    NASA Astrophysics Data System (ADS)

    Rothberg, Lewis

    2002-03-01

    We study the behavior of dendritic side group poly(p-phenylenevinylene)s upon deliberate aggregation in poor solvents. Using this strategy, we are able to reproduce film spectra and excited state decay dynamics in solution [1,2]. We show that these data can be accounted for using a model that assumes the polymer assumes essentially only two conformations [3]. This picture explains a wide variety of phenomena observed in the optical behavior that have in some cases been incorrectly attributed to other physics. We have also used the dendritic substitutions to separate the polymer backbones and investigate the efficacy of this approach to increase solid state luminescence yields. Finally, we have shear aligned these polymers to make oriented films and studied the anisotropy of the photophysics. [1] R. Jakubiak, Z. Bao and L. Rothberg, “Dendritic sidegroups as three-dimensional barriers to aggregation quenching of conjugated polymer fluorescence”, Synth. Met. 114, 61-64 (2000). [2] R. Jakubiak, Z. Bao and L.J. Rothberg, “Photoluminescence decay dynamics of dendritically substituted conjugated polymers”, Synth. Met. 116, 41-44 (2001). [3] C.J. Collison, L.J. Rothberg, V. Treemaneekarn and Y. Li, “Conformational effects on the photophysics of conjugated polymers: A two species model for MEH-PPV spectroscopy and dynamics”, Macromols. 34, 2346-2352 (2001).

  15. DNA-Templated Polymerization of Side-Chain-Functionalized Peptide Nucleic Acid Aldehydes

    PubMed Central

    Kleiner, Ralph E.; Brudno, Yevgeny; Birnbaum, Michael E.; Liu, David R.

    2009-01-01

    The DNA-templated polymerization of synthetic building blocks provides a potential route to the laboratory evolution of sequence-defined polymers with structures and properties not necessarily limited to those of natural biopolymers. We previously reported the efficient and sequence-specific DNA-templated polymerization of peptide nucleic acid (PNA) aldehydes. Here, we report the enzyme-free, DNA-templated polymerization of side-chain-functionalized PNA tetramer and pentamer aldehydes. We observed that the polymerization of tetramer and pentamer PNA building blocks with a single lysine-based side chain at various positions in the building block could proceed efficiently and sequence-specifically. In addition, DNA-templated polymerization also proceeded efficiently and in a sequence-specific manner with pentamer PNA aldehydes containing two or three lysine side chains in a single building block to generate more densely functionalized polymers. To further our understanding of side-chain compatibility and expand the capabilities of this system, we also examined the polymerization efficiencies of 20 pentamer building blocks each containing one of five different side-chain groups and four different side-chain regio- and stereochemistries. Polymerization reactions were efficient for all five different side-chain groups and for three of the four combinations of side-chain regio- and stereochemistries. Differences in the efficiency and initial rate of polymerization correlate with the apparent melting temperature of each building block, which is dependent on side-chain regio- and stereochemistry, but relatively insensitive to side-chain structure among the substrates tested. Our findings represent a significant step towards the evolution of sequence-defined synthetic polymers and also demonstrate that enzyme-free nucleic acid-templated polymerization can occur efficiently using substrates with a wide range of side-chain structures, functionalization positions within each

  16. Influence of Reversibly Associating Side Group Bond Strength on Viscoelastic Properties of Polymer Melts

    NASA Astrophysics Data System (ADS)

    Lewis, Christopher; Stewart, Kathleen; Anthamatten, Mitchell

    2013-03-01

    Reversible hydrogen-bonding between side-groups of linear polymers can sharply influence a material's dynamic mechanical behavior, giving rise to valuable shape memory and self-healing properties. Here, we investigate how bond-strength affects the bulk rheological behavior of functional poly(n-butyl acrylate) (PBA) melts. A series of random copolymers containing three different reversibly bonding groups (aminopyridine, carboxylic acid, and ureidopyrimidinone) were synthesized to systematically vary the side-group hydrogen bond strength (~26, 40, 70 kJ/mol). The materials' volumetric hydrogen-bond energy densities can be tuned by adjusting the side-group composition. By comparing the viscoelastic behavior of materials containing an equivalent bond energy density, with different bonding groups, the efficacy and cooperativity of reversible binding can be directly examined. Melt rheology results are interpreted using a state-of-ease model that assumes continuous mechanical equilibrium between applied stress and resistive stresses of entropic origin arising from a network of reversible bonds. The authors acknowledge support from funding provided by the National Science Foundation under Grant DMR-0906627

  17. Synthesis of waterborne polyurethane containing alkoxysilane side groups and the properties of the hybrid coating films

    NASA Astrophysics Data System (ADS)

    Li, Qi; Guo, Longhai; Qiu, Teng; Xiao, Weidong; Du, Dianxing; Li, Xiaoyu

    2016-07-01

    A series of waterborne polyurethane (WPU) containing alkoxysilane side groups were synthesized by using the dihydroxy functionalized alkoxysilane. The diol with trimethoxysilane groups at the side chains was synthesized via Michael addition between 3-(methacryloxypropyl)trimethoxysilane (MAPTS) and diethanolamine (DEA). The silane diol was applied as the chain extender for the NCO-endcapped prepolymer of isophorone diisocyanate, polycarbonate diol, 2,2-bis(hydroxymethyl) butyric acid and 1,4-butanediol. The products with the silane content varied from 1.2 to 16.5 wt% were dispersed in water after neutralization. The effect of the silane diol on the particle size and morphology of the WPU dispersion was studied by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. X-ray photoelectron spectroscopy (XPS) characterization was carried out on the coating film of the WPU, revealing that the long flexible side chain is favorable for the silane components to emigrate toward the film surface and crosslink during the film formation process. As a result, both the surface contact angle to water and water adsorption of the WPU coating films increased with the silane content. Furthermore, the mechanical properties including the modulus and tensile strength of the films were also improved by the incorporation of silane diol.

  18. Temperature dependence of amino acid side chain IR absorptions in the amide I' region.

    PubMed

    Anderson, Benjamin A; Literati, Alex; Ball, Borden; Kubelka, Jan

    2014-05-01

    Amide I' IR spectra are widely used for studies of structural changes in peptides and proteins as a function of temperature. Temperature dependent absorptions of amino acid side-chains that overlap the amide I' may significantly complicate the structural analyses. While the side-chain IR spectra have been investigated previously, thus far their dependence on temperature has not been reported. Here we present the study of the changes in the IR spectra with temperature for side-chain groups of aspartate, glutamate, asparagine, glutamine, arginine, and tyrosine in the amide I' region (in D2O). Band fitting analysis was employed to extract the temperature dependence of the individual spectral parameters, such as peak frequency, integrated intensity, band width, and shape. As expected, the side-chain IR bands exhibit significant changes with temperature. The majority of the spectral parameters, particularly the frequency and intensity, show linear dependence on temperature, but the direction and magnitude vary depending on the particular side-chain group. The exception is arginine, which exhibits a distinctly nonlinear frequency shift with temperature for its asymmetric CN3H5(+) bending signal, although a linear fit can account for this change to within ~1/3 cm(-1). The applicability of the determined spectral parameters for estimations of temperature-dependent side-chain absorptions in peptides and proteins are discussed.

  19. Hydrogen bonding motifs of protein side chains: descriptions of binding of arginine and amide groups.

    PubMed Central

    Shimoni, L.; Glusker, J. P.

    1995-01-01

    The modes of hydrogen bonding of arginine, asparagine, and glutamine side chains and of urea have been examined in small-molecule crystal structures in the Cambridge Structural Database and in crystal structures of protein-nucleic acid and protein-protein complexes. Analysis of the hydrogen bonding patterns of each by graph-set theory shows three patterns of rings (R) with one or two hydrogen bond acceptors and two donors and with eight, nine, or six atoms in the ring, designated R2(2)(8), R2(2)(9), and R1(2)(6). These three patterns are found for arginine-like groups and for urea, whereas only the first two patterns R2(2)(8) and R2(2)(9) are found for asparagine- and glutamine-like groups. In each case, the entire system is planar within 0.7 A or less. On the other hand, in macromolecular crystal structures, the hydrogen bonding patterns in protein-nucleic acid complexes between the nucleic acid base and the protein are all R2(2)(9), whereas hydrogen bonding between Watson-Crick-like pairs of nucleic acid bases is R2(2)(8). These two hydrogen bonding arrangements [R2(2)(9)] and R2(2)(8)] are predetermined by the nature of the groups available for hydrogen bonding. The third motif identified, R1(2)(6), involves hydrogen bonds that are less linear than in the other two motifs and is found in proteins. PMID:7773178

  20. Theoretical Studies of Interactions between O-Phosphorylated and Standard Amino-Acid Side-Chain Models in Water

    PubMed Central

    Wiśniewska, Marta; Sobolewski, Emil; Ołdziej, Stanisław; Liwo, Adam; Scheraga, Harold A.; Makowski, Mariusz

    2015-01-01

    Phosphorylation is a common post-translational modification of the amino-acid side chains (serine, tyrosine, and threonine) that contain hydroxyl groups. The transfer of the negatively charged phosphate group from an ATP molecule to such amino-acid side chains leads to changes in the local conformations of proteins and the pattern of interactions with other amino-acid side-chains. A convenient characteristic of the side chain–side chain interactions in the context of an aqueous environment is the potential of mean force (PMF) in water. A series of umbrella-sampling molecular dynamic (MD) simulations with the AMBER force field were carried out for pairs of O-phosphorylated serine (pSer), threonine (pThr), and tyrosine, (pTyr) with natural amino acids in a TIP3P water model as a solvent at 298 K. The weighted-histogram analysis method was used to calculate the four-dimensional potentials of mean force. The results demonstrate that the positions and depths of the contact minima and the positions and heights of the desolvation maxima, including their dependence on the relative orientation depend on the character of the interacting pairs. More distinct minima are observed for oppositely charged pairs such as, e.g., O-phosphorylated side-chains and positively charged ones, such as the side-chains of lysine and arginine. PMID:26100791

  1. Application of palladium-catalyzed carboxyl anhydride-boronic acid cross coupling in the synthesis of novel bile acids analogs with modified side chains.

    PubMed

    Mayorquín-Torres, Martha C; Flores-Álamo, Marcos; Iglesias-Arteaga, Martin A

    2015-09-01

    Palladium-catalyzed cross coupling of 4-methoxycarbonyl phenyboronic acid with acetylated bile acids in which the carboxyl functions was activated by formation of a mixed anhydride with pivalic anhydride afforded the cross coupled compounds, which were converted in novel side chain modified bile acids by one pot carbonyl reduction/removal of the protecting acetyl groups by Wolff-Kishner reduction. Unambiguous assignments of the NMR signals and crystal characterization of the heretofore unknown compounds are provided.

  2. Photo-Crosslinkable Shape-Memory Elastomers Containing Hydrogen-Bonding Side-Groups

    NASA Astrophysics Data System (ADS)

    Li, Jiahui; Lewis, Christopher; Anthamatten, Mitchell

    2010-03-01

    Lightly crosslinked poly(butyl acrylate) networks containing self-complementary hydrogen bonding side-groups (e.g. ureidopyrimidinones) can exhibit unique shape-memory effects. Conventional free-radical solution polymerization of monomer mixtures offers a simple approach to achieving these networks, but presents the following limitations: (i) the H-bonding side- group content is limited by its solubility; (ii) prepared networks can only be studied in their crosslinked form; and (iii) upon solvent removal, intrinsic stress is generated making shape-memory responses difficult to interpret. Here, photo-polymerization of linear prepolymers is reported as an approach to overcome these limitations. A series of linear poly (butyl acrylate)s containing light-sensitive benzophenone side- groups and H-bonding side-groups were prepared using free radical polymerization. These pre-polymers can be fully characterized in solution (NMR, GPC). Moreover, following solvent removal, they can be molded into any desired shape and subsequently photo-crosslinked to form shape-memory elastomers. The impact of H-bonding side-group content and the benzophenone side-group content on the mechanical properties of the photo-crosslinked polymer will be discussed. A constitutive model is also developed to interpret the mechanical response of these shape-memory elastomers.

  3. Formation of catechols via removal of acid side chains from ibuprofen and related aromatic acids.

    PubMed

    Murdoch, Robert W; Hay, Anthony G

    2005-10-01

    Although ibuprofen [2-(4-isobutylphenyl)-propionic acid] is one of the most widely consumed drugs in the world, little is known regarding its degradation by environmental bacteria. Sphingomonas sp. strain Ibu-2 was isolated from a wastewater treatment plant based on its ability to use ibuprofen as a sole carbon and energy source. A slight preference toward the R enantiomer was observed, though both ibuprofen enantiomers were metabolized. A yellow color, indicative of meta-cleavage, accumulated transiently in the culture supernatant when Ibu-2 was grown on ibuprofen. When and only when 3-flurocatechol was used to poison the meta-cleavage system, isobutylcatechol was identified in the culture supernatant via gas chromatography-mass spectrometry analysis. Ibuprofen-induced washed-cell suspensions also metabolized phenylacetic acid and 2-phenylpropionic acid to catechol, while 3- and 4-tolylacetic acids and 2-(4-tolyl)-propionic acid were metabolized to the corresponding methyl catechols before ring cleavage. These data suggest that, in contrast to the widely distributed coenzyme A ligase, homogentisate, or homoprotocatechuate pathway for metabolism of phenylacetic acid and similar compounds, Ibu-2 removes the acidic side chain of ibuprofen and related compounds prior to ring cleavage.

  4. A Semiautomated Assignment Protocol for Methyl Group Side Chains in Large Proteins.

    PubMed

    Kim, Jonggul; Wang, Yingjie; Li, Geoffrey; Veglia, Gianluigi

    2016-01-01

    The developments of biosynthetic specific labeling strategies for side-chain methyl groups have allowed structural and dynamic characterization of very large proteins and protein complexes. However, the assignment of the methyl-group resonances remains an Achilles' heel for NMR, as the experiments designed to correlate side chains to the protein backbone become rather insensitive with the increase of the transverse relaxation rates. In this chapter, we outline a semiempirical approach to assign the resonances of methyl-group side chains in large proteins. This method requires a crystal structure or an NMR ensemble of conformers as an input, together with NMR data sets such as nuclear Overhauser effects (NOEs) and paramagnetic relaxation enhancements (PREs), to be implemented in a computational protocol that provides a probabilistic assignment of methyl-group resonances. As an example, we report the protocol used in our laboratory to assign the side chains of the 42-kDa catalytic subunit of the cAMP-dependent protein kinase A. Although we emphasize the labeling of isoleucine, leucine, and valine residues, this method is applicable to other methyl group side chains such as those of alanine, methionine, and threonine, as well as reductively methylated cysteine side chains.

  5. The Influence of Side Group Modification in Polyphosphazenes on Hydrolysis and Cell Adhesion of Blends with PLGA

    PubMed Central

    Krogman, Nicholas R.; Weikel, Arlin L.; Kristhart, Katherine A.; Nukavaropu, Syam P.; Deng, Meng; Nair, Lakshmi S.; Laurencin, Cato T.; Allcock, Harry R.

    2009-01-01

    Polyphosphazenes have been synthesized with tris(hydroxymethyl)amino methane (THAM) side groups and with co-substituents glycine ethyl ester and alanine ethyl ester. The THAM side group was linked to the polyphosphazene backbone via the amino function. The three pendent hydroxyl functions on each THAM side group were utilized for hydrogen bonding association with poly(glycolic-lactic acid) (PLGA). Co-substitution of the polyphosphazene with both THAM and glycine or alanine ethyl esters was employed to avoid the insolubility of the single-substituent THAM -substituted polyphosphazenes. Both poly[(tris(hydroxymethyl)aminomethane)(ethyl glycinato)phosphazene] and poly[(tris(hydroxymethyl)aminomethane)(ethyl alanato)phosphazene] (1:1 ratio of side groups) were blended with PLGA (50:50) or PLGA (85:15). DSC analysis indicated miscible blend formation, irrespective of the detailed molecular structure of the polyphosphazene or the composition of PLGA in the blend. Hydrolysis studies of the polyphosphazene:PLGA (50:50) blends indicated that the PLGA component hydrolyzed more rapidly than the polyphosphazene. Primary osteoblast cell studies showed good cell adhesion to the polymer blends during 14 days, but subsequent limited cell spreading due to increased surface roughness as the two polymers eroded at different rates. PMID:19345410

  6. In Vitro Enzymatic Synthesis of New Penicillins Containing Keto Acids as Side Chains

    PubMed Central

    Ferrero, Miguel A.; Reglero, Angel; Martínez-Blanco, Honorina; Fernández-Valverde, Martiniano; Luengo, Jose M.

    1991-01-01

    Seven different penicillins containing α-ketobutyric, β-ketobutyric, γ-ketovaleric, α-ketohexanoic, δ-ketohexanoic, ε-ketoheptanoic, and α-ketooctanoic acids as side chains have been synthesized in vitro by incubating the enzymes phenylacetyl coenzyme A (CoA) ligase from Pseudomonas putida and acyl-CoA:6-aminopenicillanic acid acyltransferase from Penicillium chrysogenum with CoA, ATP, Mg2+, dithiothreitol, 6-aminopenicillanic acid, and the corresponding side chain precursor. PMID:1952871

  7. Phosphazenes with Olefinic Side Groups: Proton Abstraction Reactions of Fluoroalkoxy Derivatives.

    DTIC Science & Technology

    1982-06-24

    OPh) (OC(Li)=CF2) 13 and [NP(OC(Li)CF2)2]3 1 respectively. These species are stable in solution at -78*C, but react with electrophiles such as 2...an -OCH2CF3 side group to generate an -OC(M)-CF2 unit. Subsequent treatment with an electrophile was designed to yield an -OC(R)-CF2 side group...resonances for the fluorine atoms in 2 and 5 appeared as multiplets due to the slight differences in chemical shift between the cis and trans

  8. From labdanes to drimanes. Degradation of the side chain of dihydrozamoranic acid.

    PubMed

    Rodilla, Jesús M L; Díez, D; Urones, J G; Rocha, Pedro M

    2004-04-30

    A new route for the degradation of the saturated side chain of dihydrozamoranic acid has been devised, giving an advanced intermediate, compound 14, useful for the synthesis of insect antifeedants such as warburganal and polygodial.

  9. A new classification of the amino acid side chains based on doublet acceptor energy levels.

    PubMed Central

    Sneddon, S F; Morgan, R S; Brooks, C L

    1988-01-01

    We describe a new classification of the amino acid side chains based on the potential energy level at which each will accept an extra (doublet) electron. The doublet acceptor energy level, and the doublet acceptor orbital were calculated using semiempirical INDO/2-UHF molecular orbital theory. The results of these calculations show that the side chains fall into four groups. We have termed these groups repulsive, insulating, semiconducting, and attractive in accordance with where each lies on the relative energy scale. We use this classification to examine the role of residues between the donor and acceptor in modulating the rate and mechanism of electron transfer in proteins. With the calculated acceptor levels, we construct a potential barrier for those residues between the donor and acceptor. It is the area beneath this barrier that determines the decay of electronic coupling between donor and acceptor, and thus the transfer rate. We have used this schematic approach to characterize the four electron transfer pathways in myoglobin recently studied by Mayo et al. (Mayo, S.L., W.R. Ellis, R.J. Crutchley, and H.B. Gray. 1986. Science [Wash. DC]. 233:948-952). PMID:3342271

  10. Cephalosporins. II. 7-(O-Aminomethyl-phnylacetamido) cephalosporanic acids with six membered heterocycles in the C-3 side chain.

    PubMed

    Naito, T; Okumura, J; Kasai K-I; Masuko, K; Hoshi, H

    1977-09-01

    7-(o-Aminomethylphenylacetamido)cephalosporanic acids with six-membered heterocycles in the C-3 side chain were prepared by nucleophillic substitution of 7-ACA at the C-3 acetoxy group followed by N-acylation of the 7-amino group. The 7-side chain acid, o-aminomethylphenylacetic acid (5), was prepared by two new convenient routes, which involved Schmidt reaction of indanone (2) followed by cleavage of the lactam ring or reduction of o-cyanophenylacetic acid (10) starting from o-nitrotoluene. The antibacterial activity of the cephalosporins in this series depends on the heterocycle in the C-3 side chain. In general pyridazines gave cephalosporin derivatives possessing better activity than those with a pyridine or pyrimidine ring. The most active member of the new cephalosporins was 7-(o-aminomethylphenylacetamido)-3-(6-hydroxypyridazin-3-ylthilmethyl)-3-cephem-4-carboxylic acid (BB-S 150) (1g) which has in vitro antibacterial activity superior to cephalothin and cefazolin against both gram-negative and gram-positive organisms. The in vitro activity of BB-S 150 determined in mice was superior to cephalothin and comparable to cefazolin.

  11. Arabidopsis GUX Proteins Are Glucuronyltransferases Responsible for the Addition of Glucuronic Acid Side Chains onto Xylan

    EPA Science Inventory

    Xylan, the second most abundant cell wall polysaccharide, is composed of a linear backbone of β-(1,4)-linked xylosyl residues that are often substituted with sugar side chains, such as glucuronic acid (GlcA) and methylglucuronic acid (MeGlcA). It has recently been shown that muta...

  12. Methoxymethyl (MOM) group nitrogen protection of pyrimidines bearing C-6 acyclic side-chains.

    PubMed

    Kraljević, Tatjana Gazivoda; Petrović, Martina; Krištafor, Svjetlana; Makuc, Damjan; Plavec, Janez; Ross, Tobias L; Ametamey, Simon M; Raić-Malić, Silvana

    2011-06-20

    Novel N-methoxymethylated (MOM) pyrimidine (4-13) and pyrimidine-2,4-diones (15-17) nucleoside mimetics in which an isobutyl side-chain is attached at the C-6 position of the pyrimidine moiety were synthesized. Synthetic methods via O-persilylated or N-anionic uracil derivatives have been evaluated for the synthesis of N-1- and/or N-3-MOM pyrimidine derivatives with C-6 acyclic side-chains. A synthetic approach using an activated N-anionic pyrimidine derivative afforded the desired N,N-1,3-diMOM and N-1-MOM pyrimidines 4 and 5 in good yield. Introduction of fluorine into the side-chain was performed with DAST as the fluorinating reagent to give a N,N-1,3-diMOM pyrimidine 13 with a 1-fluoro-3-hydroxyisobutyl moiety at C-6. Conformational study of the monotritylated N-1-MOM pyrimidine 12 by the use of the NOE experiments revealed the predominant conformation of the compound to be one where the hydroxymethyl group in the C-6 side-chain is close to the N-1-MOM moiety, while the OMTr is in proximity to the CH(3)-5 group. Contrary to this no NOE enhancements between the N-1-MOM group and hydroxymethyl or fluoromethyl protons in 13 were observed, which suggested a nonrestricted rotation along the C-6 side-chain. Fluorinated N,N-1,3-diMOM pyrimidine 13 emerged as a model compound for development of tracer molecules for non-invasive imaging of gene expression using positron emission tomography (PET).

  13. Synthesis and photophysical properties of polyfluorene with dipicolylamine groups on the side chain: highly selective and sensitive detection of histidine.

    PubMed

    Zhang, Wenjun; Qin, Jingui; Yang, Chuluo

    2013-01-25

    Two new polyfluorenes with dipicolylamine (DPA) pendant, PF-TDPA and PF-HDPA, are designed and synthesized by pre- and post-functionalization, respectively. PF-TDPA with a rigid side chain shows a selective fluorescence quenching upon the addition of Cu(2+) in a mixture solution of tetrahydrofuran and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer. What is more, the PF-TDPA/Cu(2+) complex can selectively detect histidine over other amino acids with a fluorescence recovery. In contrast, PF-HDPA with a flexible spacer exhibits a fluorescence quenching to Cu(2+) but slightly fluorescence recovery after the addition of histidine. This indicates that the proper distance between the two DPA groups play an important role in the detection of histidine.

  14. Novel method for the preparation of polymethacrylates with nonlinear optically active side groups

    NASA Astrophysics Data System (ADS)

    Strohriegl, Peter; Mueller, Harry; Nuyken, Oskar

    1993-01-01

    Because of their excellent optical properties, a variety of polymethacrylates with pendant NLO-chromophores has been prepared and investigated by different research groups. The method normally used for the synthesis of these polymers is the free radical polymerization of the corresponding methacrylates with NLO-active side groups. However, the NLO- chromophores, usually large conjugated molecules with an electron donor and an electron acceptor substituent, often contain a number of functional groups, e.g., nitro- or azo groups. These may act as retarders or inhibitors in a free radical polymerization. So in many cases the yields are not quantitative and the molecular weights are quite low. We present an alternative method for the preparation of polymethacrylates with pendant NLO-chromophores, the polymeranalogous esterification of poly(methacryloyl chloride). In a first step, reactive prepolymers are prepared by the free radical polymerization of methacryloyl chloride (MAC1) or by copolymerization of MAC1 with methyl methacrylate (MMA). These prepolymers are esterified using NLO-active side groups with a hydroxy-terminated spacer. Well defined, high molecular weight polymethacrylates with high dye contents can be prepared by this method. A copolymer with 19 mole% of azochromophores exhibits an electro-optical coefficient of 9 pm/V at 1300 mm after poling, whereas 19 pm/V (1500 nm) were measured for a polymer with 90 mole% of NLO active azobenzene side groups. In addition, the novel method provides easy access to some novel copolymers with both NLO-active azobenzene units and photocrosslinkable cinnamoyl groups.

  15. THERMAL AND SPECTROSCOPIC ANALYSES OF CAUSTIC SIDE SOLVENT EXTRACTION SOLVENT CONTACTED WITH 1 MOLARAND 3 MOLAR NITRIC ACID

    SciTech Connect

    Fondeur, F; David Hobbs, D; Samuel Fink, S

    2007-07-23

    Thermal and spectroscopic analyses were performed on multiple layers formed from contacting Caustic Side Solvent Extraction (CSSX) solvent with 1 M or 3 M nitric acid. A slow chemical reaction occurs (i.e., over several weeks) between the solvent and 1 M or 3 M nitric acid as evidenced by color changes and the detection of nitro groups in the infrared spectrum of the aged samples. Thermal analysis revealed that decomposition of the resulting mixture does not meet the definition of explosive or deflagrating material.

  16. Solvation thermodynamics of amino acid side chains on a short peptide backbone

    SciTech Connect

    Hajari, Timir; Vegt, Nico F. A. van der

    2015-04-14

    The hydration process of side chain analogue molecules differs from that of the actual amino acid side chains in peptides and proteins owing to the effects of the peptide backbone on the aqueous solvent environment. A recent molecular simulation study has provided evidence that all nonpolar side chains, attached to a short peptide backbone, are considerably less hydrophobic than the free side chain analogue molecules. In contrast to this, the hydrophilicity of the polar side chains is hardly affected by the backbone. To analyze the origin of these observations, we here present a molecular simulation study on temperature dependent solvation free energies of nonpolar and polar side chains attached to a short peptide backbone. The estimated solvation entropies and enthalpies of the various amino acid side chains are compared with existing side chain analogue data. The solvation entropies and enthalpies of the polar side chains are negative, but in absolute magnitude smaller compared with the corresponding analogue data. The observed differences are large; however, owing to a nearly perfect enthalpy-entropy compensation, the solvation free energies of polar side chains remain largely unaffected by the peptide backbone. We find that a similar compensation does not apply to the nonpolar side chains; while the backbone greatly reduces the unfavorable solvation entropies, the solvation enthalpies are either more favorable or only marginally affected. This results in a very small unfavorable free energy cost, or even free energy gain, of solvating the nonpolar side chains in strong contrast to solvation of small hydrophobic or nonpolar molecules in bulk water. The solvation free energies of nonpolar side chains have been furthermore decomposed into a repulsive cavity formation contribution and an attractive dispersion free energy contribution. We find that cavity formation next to the peptide backbone is entropically favored over formation of similar sized nonpolar side

  17. Structure-activity relationship study of vitamin D analogs with oxolane group in their side chain.

    PubMed

    Belorusova, Anna Y; Martínez, Andrea; Gándara, Zoila; Gómez, Generosa; Fall, Yagamare; Rochel, Natacha

    2017-04-02

    Synthetic analogs of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) have been developed with the goal of improving the biological profile of the natural hormone for therapeutic applications. Derivatives of 1,25(OH)2D3 with the oxolane moiety branched in the side chain at carbon C20, act as Vitamin D nuclear Receptor (VDR) superagonists being several orders of magnitude more active than the natural ligand. Here, we describe the synthesis and biological evaluation of three diastereoisomers of (1S, 3R)-Dihydroxy-(20S)-[(2″-hydroxy-2″-propyl)-tetrahydrofuryl]-22,23,24,25,26,27-hexanor-1α-hydroxyvitamin D3, with different stereochemistry at positions C2 and C5 of the oxolane ring branched at carbon C22 (1, C2RC5S; 2, C2SC5R; 3, C2SC5S). These compounds act as weak VDR agonist in transcriptional assays with compound 3 being the most active. X-ray crystallographic analysis of the VDR ligand-binding domain accommodating the three compounds indicates that the oxolane group branched at carbon C22 is not constrained as in case of compound with oxolane group branched at C20 leading to the loss of interactions of the triene group and increased flexibility of the C/D-rings and of the side chain.

  18. Molecularly oriented surface relief formation in polymethacrylates comprising N-benzylideneaniline derivative side groups

    NASA Astrophysics Data System (ADS)

    Kawatsuki, Nobuhiro; Hosoda, Risa; Kondo, Mizuho; Sasaki, Tomoyuki; Ono, Hiroshi

    2014-12-01

    Molecularly oriented surface relief (SR) formation in polymethacrylates with N-benzylideneaniline (NBA) derivative side groups is investigated by holographic exposure using a 325 nm He-Cd laser. Because the NBA moieties show a photoinduced orientation perpendicular to the polarization of light, polarization holography successfully forms a molecularly oriented SR structure in accordance with the polarization distribution that includes p-polarized components. Although intensity holography induces molecular orientation, it does not generate a satisfactory SR structure. In all the holographic modes, the SR depth depends on the direction of the C=N bonds in the NBA moieties and the photoproducts affect the SR formation ability.

  19. Supramolecular control of self-assembling terthiophene-peptide conjugates through the amino acid side chain

    SciTech Connect

    Lehrman, Jessica A.; Cui, Honggang; Tsai, Wei-Wen; Moyer, Tyson J.; Stupp, Samuel I.

    2013-07-30

    The self-assembly of oligothiophene–peptide conjugates can be directed through the systematic variation of the peptide sequence into different nanostructures, including flat spicules, nanotubes, spiral sheets, and giant, flat sheets. Furthermore, the assembly of these molecules is not controlled by steric interactions between the amino acid side chains.

  20. Side Group Addition to the PAH Coronene by UV Photolysis in Cosmic Ice Analogs

    NASA Technical Reports Server (NTRS)

    Bernstein, Max P.; Elsila, Jamie E.; Dworkin, Jason P.; Sandford, Scott A.; Allamandola, Louis J.; Zare, Richard N.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    Ultraviolet photolysis of various ice mixtures at low temperature and pressure caused the addition of amino (-NH2), methyl (-CH3), methoxy (-OCH3), and cyano (-CN) functional groups to the polycyclic aromatic hydrocarbon (PAH) coronene (C22H12). The implications of these results for interstellar and meteoritic chemistry are discussed. Previously only simple PAH photo-oxidation had been reported. This work represents the first experimental evidence that ice photochemistry may have contributed to aromatics bearing carbon and nitrogen containing side groups that are detected in primitive meteorites and interplanetary dust particles. Furthermore, these results suggest a wider range of modified PAHs should be expected in interstellar lees and materials predating solar system formation.

  1. Synthesis and Characterization of Poly(hydroxyethyl methacrylate) Hydrogels Bearing Reversibly Associating Side Groups

    NASA Astrophysics Data System (ADS)

    Lewis, Christopher; Li, Jiahui; Anthamatten, Mitchell

    2012-02-01

    Poly(hydroxyethyl methacrylate) (poly(HEMA)) is a technologically important hydrogel that can be processed into different shapes and is best known for its role in contact lenses. However, applications of water swollen polyHEMA are limited by its poor mechanical properties. We are studying the influence of reversibly associating side groups on the behavior of poly(HEMA) hydrogels. In non-polar media, it is well known that ureidopyrimidinone (UPy) groups self-associate to form hydrogen bonded dimers (DDAA); however their behavior in water-swollen hydrogels is unclear. A series of poly(HEMA) linear polymers of controlled molecular weight with varying UPy content have been prepared using a reversible addition-fragmentation chain transfer (RAFT) polymerization technique. UPy content significantly reduces water swelling and improves mechanical properties. The degree of hydrogen bonding within water swollen hydrogels is studied, and properties of functional hydrogel polymers and networks are compared to an unswollen hydrophobic analog.

  2. Two groups challenge US acid rain efforts

    SciTech Connect

    Not Available

    1987-11-01

    In its report, Acid Rain Invades Our National Parks, the National Parks and Conservation Association (NPCA) says acid rain is being detected at all 27 national park monitoring sites. In 1980, 87 national parks expressed concern in a NPCA survey over acid rain. Repolled in 1986, more than half of the respondents reported that no research on acid rain was under way. The NPCA report concludes that the alarm that was sounded in 1980 fell largely on deaf ears, and calls for the structural and scientific reorganization of the National Park Service. The National Audubon Society shares NPCA's dissatisfaction with federal efforts to tackle the problem of acid rain and has taken testing into its own hands. Through its Citizens Acid Rain Monitoring Network, Audubon volunteers have collected readings of acidity at 64 monitoring stations in 31 states since July.

  3. Mechanical Properties and Osteocompatibility of Novel Biodegradable Alanine Based Polyphosphazenes: Side Group Effects

    PubMed Central

    Sethuraman, Swaminathan; Nair, Lakshmi S.; El-Amin, Saadiq; Nguyen, My-Tien; Singh, Anurima; Krogman, Nick; Greish, Yaser E.; Allcock, Harry R.; Brown, Paul W.; Laurencin, Cato T.

    2010-01-01

    The versatility of polymers for tissue regeneration lies in the feasibility to modulate the physical and biological properties by varying the side groups grafted to the polymers. Biodegradable polyphosphazenes are high molecular weight polymers with alternating nitrogen and phosphorus atoms in the backbone. This study is the first of its kind to systematically investigate the effect of side group structure on the compressive strength of novel biodegradable polyphosphazene based polymers as potential materials for tissue regeneration. The alanine polyphosphazene based polymers, poly[bis(ethyl alanato) phosphazene] (PNEA), poly[(50% ethyl alanato) (50% methyl phenoxy) phosphazene] (PNEA50mPh50), poly[(50% ethyl alanato) (50% phenyl phenoxy) phosphazene] (PNEA50PhPh50) where investigated to demonstrate their mechanical properties and osteocompatibility. Results of mechanical testing studies demonstrated the nature and the ratio of the pendent groups attached to the polymer backbone play a significant role in determining the mechanical properties of the resulting polymer. The compressive strength of PNEA50PhPh50 was significantly higher than poly(lactide-co-glycolide) (85:15 PLAGA) (p<0.05). Additional studies evaluated the cellular response and gene expression of primary rat osteoblast cells on PNEA, PNEA50mPh50 and PNEA50PhPh50 films as candidates for bone tissue engineering applications. Results of the in vitro osteocompatibility evaluation demonstrated that cells adhere, proliferate, and maintain their phenotype when seeded directly on the surface of PNEA, PNEA50mPh50, and PNEA50PhPh50 Moreover cells on the surface of the polymers expressed type I collagen, alkaline phosphatase, osteocalcin, osteopontin, and bone sialoprotein which are characteristic genes for osteoblast maturation, differentiation, and mineralization. PMID:20004751

  4. Modeling of recognition sites of nucleic acid bases aaand amide side chains of amino acids. Combination of experimental and theoretical approaches

    NASA Astrophysics Data System (ADS)

    Shelkovsky, V. S.; Stepanian, S. G.; Galetich, I. K.; Kosevich, M. V.; Adamowicz, L.

    2002-09-01

    A combined experimental-theoretical approach to modeling of building blocks of recognition complexes formed by nucleic acid bases and the amino-acids side-chain amino group is reviewed. The approach includes the temperature dependent field-ionization mass spectrometry and ab initio quantum chemical calculations. The mass spectrometric technique allows determination of interaction enthalpies of biomolecules in the gas phase, and the results it produces are directly comparable to the results obtained through theoretical modeling. In our works we have analyzed both thermodynamic and structural aspects of the recognition complexes of four canonical nucleic acid bases and acrylamide, which models the side chain of asparagine and glutamine. It has been shown that all bases can interact with amide group of the amino acids via their Watson-Crick sites when being incorporated into a single strand DNA or RNA. Stability of the complexes studied, expressed as -Δ H (kJ mole^{-1}) decreases as: m^9Gua (-59.5) > m^1Cyt (-57.0) > m^9Ade (-52.0) gg m^1Ura (-40.6). We have determined that in the double stranded DNA only purine bases can be recognized.

  5. Dielectric relaxation and molecular dynamics of liquid crystalline side-chain oligoacrylates with 4-cyanazobensene side mesogenic groups in external electric or mechanical fields

    NASA Astrophysics Data System (ADS)

    Nikonorova, N. A.; Borisova, T. I.; Stakhanov, A. I.; Shibaev, Valery P.

    1998-01-01

    Dielectric relaxation and molecular mobility have ben investigated over the frequency range 60Hz-1MHz between 160 degrees C and 150 degrees C for smectic side-chain oligoacrylates with 4-cyanazobenzene mesogenic side groups and methylene spacers of different length. The studied oligomers were oriented by electric or mechanic fields. In the range of subglass temperatures two dielectric processes were observed - the (gamma) 1 and the (beta) . The (gamma) 1 process reflects the local motion of the spacer groups and the (beta) process is connected with the local motion of the mesogenic moieties. the molecular mobility of the (gamma) 1 process increases with the spacer lengthening but at the same time in the case of the (beta) process the mobility is not changed. In LC state near Tg transition, the temperature-frequency dependencies of dielectric losses show two cooperative processes, the (alpha) - an the (delta) , related to the reorientation of the transverse or longitudinal components of the dipole moment of the mesogenic group, correspondingly. The preliminary orientation in external electric or mechanic fields leads to the establishment of planar or homeotropic orientation of the side mesogenic groups. The order parameters of oriented films were calculated. It was shown the planar or homeotropic orientation of mesogenic groups did not influence on relaxation times of the observed dielectric processes.

  6. Neighbouring group participation in the unblocking of phosphotriesters of nucleic acids.

    PubMed Central

    de Rooij, J F; Wille-Hazeleger, G; Burgers, P M; van Boom, J H

    1979-01-01

    Two examples of neighbouring group participation during the removal of protecting groups from phosphotriesters of partially or fully protected intermediates of nucleic acids are presented. The first example shows that ammonolysis of aryl groups from phosphotriesters of partially protected - 5'- hydroxy free - nucleic acids (e.g., 4b approximately to; Ar=2C1C 6H4) gives rise to the formation of unnatural nucleic acids (e.g., 7 approximately to and 8 approximately to). The second one illustrates that fluoride ion promoted hydrolysis of 2,2,2-trichloroethyl groups from phosphotriesters of fully protected nucleic acids (e.g., 18a approximately to), having t-butyldimethylsilyl groups at the 2'-positions, leads to the formation of a considerable amount of side-products (e.g., 20 approximately to and 21 approximately to). PMID:461188

  7. Integrated process of distillation with side reactors for synthesis of organic acid esters

    DOEpatents

    Panchal, Chandrakant B; Prindle, John C; Kolah, Aspri; Miller, Dennis J; Lira, Carl T

    2015-11-04

    An integrated process and system for synthesis of organic-acid esters is provided. The method of synthesizing combines reaction and distillation where an organic acid and alcohol composition are passed through a distillation chamber having a plurality of zones. Side reactors are used for drawing off portions of the composition and then recycling them to the distillation column for further purification. Water is removed from a pre-reactor prior to insertion into the distillation column. An integrated heat integration system is contained within the distillation column for further purification and optimizing efficiency in the obtaining of the final product.

  8. Functionalization of metal-organic frameworks through the postsynthetic transformation of olefin side groups.

    PubMed

    Hindelang, Konrad; Kronast, Alexander; Vagin, Sergei I; Rieger, Bernhard

    2013-06-17

    For the first time, the adaptability of the C=C double bond as a versatile precursor for the postsynthetic modification (PSM) of microporous materials was extensively investigated and evaluated. Therefore, an olefin-tagged 4,4'-bipyridine linker was synthesized and successfully introduced as pillar linker within a 9,10-triptycenedicarboxylate (TDC) zinc paddle-wheel metal-organic framework (MOF) through microwave-assisted synthesis. Different reactions, predominately used in organic chemistry, were tested, leading to the development of new postsynthetic reactions for the functionalization of solid materials. The postsynthetic oxidation of the olefin side groups applying osmium tetroxide (OsO₄) as a catalyst led to the formation of a microporous material with free vicinal diol functionalities. The epoxidation with dimethyldioxirane (DMDO) enabled the synthesis of epoxy-functionalized MOFs. In addition to that, reaction procedures for a postsynthetic hydroboration with borane dimethyl sulfide as well as a photoinduced thiol-ene click reaction with ethyl mercaptan were developed. For all of these PSMs, yields of more than 90% were obtained, entirely maintaining the crystallinity of the MOFs. Since the direct introduction of the corresponding groups by means of pre-synthetic approaches is hardly possible, these new PSMs are useful tools for the functionalization of porous solids towards applications such as selective adsorption, separation, and catalysis.

  9. Controlling Miscibility in Polyethylene-Polynorbornene Block Copolymers via Side-Group Chemistry

    NASA Astrophysics Data System (ADS)

    Mulhearn, William; Register, Richard

    Block copolymers containing a crystallizable block, such as polyethylene (PE), and an amorphous block with high glass transition temperature (Tg) are an interesting class of materials since the rigid glassy block can improve the mechanical response of the article under strain by reinforcing the crystal fold surface. However, to prepare an easily processable PE-containing block copolymer it is necessary to avoid microphase separation in the melt by selection of amorphous blocks with weak repulsive interactions against PE (low Flory interaction parameter χ or interaction energy density X) . Most such low- χ polymers are chemically similar to PE, such as copolymers of ethylene and a small amount of an α-olefin, and therefore exhibit similarly low glass transition temperatures. This work investigates a series of low- and high-Tg polymers based on substituted norbornene monomers, polymerized via ring-opening metathesis polymerization (ROMP). Hydrogenated polynorbornene derivatives possess a wide range of glass transition temperatures, and miscibility with PE can be readily tuned by the choice of substituents on the monomers (e.g. aromatic vs. aliphatic groups). Two species investigated, hydrogenated poly(cyclohexyl norbornene) and hydrogenated poly(norbornyl norbornene), have high Tg and also remain miscible with polyethylene to high molecular weight. Furthermore, we develop a set of mixing rules to qualitatively predict the solubility behavior of substituted ROMP polynorbornenes as a function of their side-groups.

  10. Effect of Mesophase Order on the Dynamics of Side Group Liquid Crystalline Polymers

    SciTech Connect

    Auad, M.L.; Kempe, M.D.; Kornfield, J.A.; Rendon, S.; Burghardt, W.R.; Yoon, K.

    2010-07-13

    Rheology and X-ray scattering were employed to probe the viscoelastic properties and structural transitions of model cyano-biphenyl-based side-group liquid-crystalline polymers (SGLCPs) with molecular weights ranging from 91 to 1900 kg/mol. Temperature-dependent rheological data show a rapid change in dynamics over a small temperature range. Small-angle X-ray scattering reveals these changes to be associated with an isotropic to smectic transition with an appreciable biphasic region. The presence of a biphasic region is attributed to inhomogeneity in chain structure resulting from incomplete attachment of mesogens to every monomeric unit in the SGLCP polymer. While isotropic and smectic phase data may be separately time-temperature shifted to create master curves for the individual phases, we argue against attempts to achieve superposition between the two phases in the high-frequency regime, since smectic ordering may not simply slow the dynamics but also increase the modulus of the sample. Molecular weight has a strong influence on rheology in the isotropic phase, where an entanglement plateau emerges; however, the smectic-phase rheology is dominated by the layer structure and is fairly insensitive to molecular weight.

  11. Observation of the side chain O-methylation of glutamic acid or aspartic acid containing model peptides by electrospray ionization-mass spectrometry.

    PubMed

    Atik, A Emin; Guray, Melda Z; Yalcin, Talat

    2017-03-15

    O-methylation of the side chains of glutamic acid (E) and aspartic acid (D) residues is generally observed modification when an acidified methanol/water (MeOH/dH2O) mixture is used as a solvent system during sample preparation for proteomic research. This chemical modification may result misidentification with endogenous protein methylation; therefore, a special care should be taken during sample handling prior to mass spectrometric analysis. In the current study, we systematically examined the extent of E/D methylation and C-terminus carboxyl group of synthetic model peptides in terms of different incubation temperatures, storage times, and added acid types as well as its percentages. To monitor these effects, C-terminus amidated and free acid forms of synthetic model peptides comprised of E or D residue(s) have been analyzed by electrospray ionization-mass spectrometry (ESI-MS). Additionally, LC-MS/MS experiments were performed to confirm the formation of methylated peptide product. The results showed that the rate of methylation was increased as the temperature increases along with prolong incubation times. Moreover, the extent of methylation was remarkably high when formic acid (FA) used as a protonation agent instead of acetic acid (AA). In addition, it was found that the degree of methylation was significantly decreased by lowering acid percentages in ESI solution. More than one acidic residue containing model peptides have been also used to explore the extent of multiple methylation reaction. Lastly, the ethanol (EtOH) and isopropanol (iPrOH) have been substituted separately with MeOH in sample preparation step to investigate the extent of esterification reaction under the same experimental conditions. However, in the positive perspective of view, this method can be used as a simple, rapid and cheap method for methylation of acidic residues under normal laboratory conditions.

  12. Stabilization Effect of Amino Acid Side Chains in Peptide Assemblies on Graphite Studied by Scanning Tunneling Microscopy.

    PubMed

    Guo, Yuanyuan; Hou, Jingfei; Zhang, Xuemei; Yang, Yanlian; Wang, Chen

    2017-02-03

    An analysis is presented of the effects of amino acid side chains on peptide assemblies in ambient conditions on a graphite surface. The molecularly resolved assemblies of binary peptides are examined with scanning tunneling microscopy. A comparative analysis of the assembly structures reveals that the lamellae width has an appreciable dependence on the peptide sequence, which could be considered as a manifestation of a stabilizing effect of side-chain moieties of amino acids with high (phenylalanine) and low (alanine, asparagine, histidine and aspartic acid) propensities for aggregation. These amino acids are representative for the chemical structures involving the side chains of charged (histidine and aspartic acid), aromatic (phenylalanine), hydrophobic (alanine), and hydrophilic (asparagine) amino acids. These results might provide useful insight for understanding the effects of sequence on the assembly of surface-bound peptides.

  13. Entropy and enthalpy of interaction between amino acid side chains in nanopores

    SciTech Connect

    Vaitheeswaran, S.; Thirumalai, D.

    2014-12-14

    Understanding the stabilities of proteins in nanopores requires a quantitative description of confinement induced interactions between amino acid side chains. We use molecular dynamics simulations to study the nature of interactions between the side chain pairs ALA-PHE, SER-ASN, and LYS-GLU in bulk water and in water-filled nanopores. The temperature dependence of the bulk solvent potentials of mean force and the interaction free energies in cylindrical and spherical nanopores is used to identify the corresponding entropic and enthalpic components. The entropically stabilized hydrophobic interaction between ALA and PHE in bulk water is enthalpically dominated upon confinement depending on the relative orientations between the side chains. In the case of SER-ASN, hydrogen bonded configurations that are similar in bulk water are thermodynamically distinct in a cylindrical pore, thus making rotamer distributions different from those in the bulk. Remarkably, salt bridge formation between LYS-GLU is stabilized by entropy in contrast to the bulk. Implications of our findings for confinement-induced alterations in protein stability are briefly outlined.

  14. Model photo-responsive elastomers based on the self-assembly of side group liquid crystal triblock copolymers (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Kurji, Zuleikha; Kornfield, Julia A.; Kuzyk, Mark G.

    2015-10-01

    We report the synthesis of azobenzene-containing coil-liquid crystal-coil triblock copolymers that form uniform and highly reproducible elastomers by self-assembly. To serve as actuators to (non-invasively) steer a fiber optic, for example in deep brain stimulation, the polymers are designed to become monodomain "single liquid crystal" elastomers during the fiber-draw process and to have a large stress/strain response to stimulation with either light or heat. A fundamental scientific question that we seek to answer is how the interplay between the concentration of photoresponsive mesogens and the proximity to the nematic-isotropic transition governs the sensitivity of the material to stimuli. Specifically, a matched pair of polymers, one with ~5% azobenzene-containing side groups (~95% cyanobiphenyl side groups) and the other with 100% cyanobiphenyl side groups were synthesized from identical triblock pre-polymers (with polystyerene end blocks and 1,2-polybutadiene midblocks). These can be blended in various ratios to prepare a series of elastomers that are precisely matched in terms of the backbone length between physical crosslinks (because each polymer is derived from the same pre-polymer), while differing in % azobenzene side groups, allowing the effect of concentration of photoresponsive groups to be unambiguously determined.

  15. Amino acids from the late Precambrian Thule group, Greenland.

    PubMed

    Akiyama, M; Shimoyama, A; Ponnamperuma, C

    1982-06-01

    Amino acids were recovered at concentration level of 10-9 M/g from the interior of chert and dolomite of the Late Precambrian Thule Group. Examination of the stability of amino acids in chert under dry-heating conditions suggests that these amino acids have been preserved with a predominance of L-enantiomers in the precambrian chert. Enantiomer analysis of amino acids in dolomite showed a thermal effect resulting from a late precambrian igneous intrusion. This evidence indicates that the amino acids isolated from the Thule samples were chemical fossils and not recent contaminants.

  16. NMR Scalar Couplings across Intermolecular Hydrogen Bonds between Zinc-Finger Histidine Side Chains and DNA Phosphate Groups.

    PubMed

    Chattopadhyay, Abhijnan; Esadze, Alexandre; Roy, Sourav; Iwahara, Junji

    2016-10-10

    NMR scalar couplings across hydrogen bonds represent direct evidence for the partial covalent nature of hydrogen bonds and provide structural and dynamic information on hydrogen bonding. In this article, we report heteronuclear (15)N-(31)P and (1)H-(31)P scalar couplings across the intermolecular hydrogen bonds between protein histidine (His) imidazole and DNA phosphate groups. These hydrogen-bond scalar couplings were observed for the Egr-1 zinc-finger-DNA complex. Although His side-chain NH protons are typically undetectable in heteronuclear (1)H-(15)N correlation spectra due to rapid hydrogen exchange, this complex exhibited two His side-chain NH signals around (1)H 14.3 ppm and (15)N 178 ppm at 35 °C. Through various heteronuclear multidimensional NMR experiments, these signals were assigned to two zinc-coordinating His side chains in contact with DNA phosphate groups. The data show that the Nδ1 atoms of these His side chains are protonated and exhibit the (1)H-(15)N cross-peaks. Using heteronuclear (1)H, (15)N, and (31)P NMR experiments, we observed the hydrogen-bond scalar couplings between the His (15)Nδ1/(1)Hδ1 and DNA phosphate (31)P nuclei. These results demonstrate the direct involvement of the zinc-coordinating His side chains in the recognition of DNA by the Cys2His2-class zinc fingers in solution.

  17. Comparing Amino Acid Abundances and Distributions Across Carbonaceous Chondrite Groups

    NASA Technical Reports Server (NTRS)

    Burton, Aaron S.; Callahan, Michael P.; Glavin, Daniel P.; Elsila, Jamie E.; Dworkin, Jason P.

    2012-01-01

    Meteorites are grouped according to bulk properties such as chemical composition and mineralogy. These parameters can vary significantly among the different carbonaceous chondrite groups (CI, CM, CO, CR, CH, CB, CV and CK). We have determined the amino acid abundances of more than 30 primary amino acids in meteorites from each of the eight groups, revealing several interesting trends. There are noticeable differences in the structural diversity and overall abundances of amino acids between meteorites from the different chondrite groups. Because meteorites may have been an important source of amino acids to the prebiotic Earth and these organic compounds are essential for life as we know it, the observed variations of these molecules may have been important for the origins of life.

  18. Crystalline arrays of side chain modified bile acids derivatives. Two novel self-assemblies based on π-π and belly-to-belly interactions.

    PubMed

    Mayorquín-Torres, Martha C; Arcos-Ramos, Rafael; Flores-Álamo, Marcos; Iglesias-Arteaga, Martín A

    2016-11-01

    Crystalline derivatives of side chain modified bile acids were efficiently prepared from the naturally occurring steroids by palladium-catalyzed cross coupling reaction as a key step. The solvent-free crystalline bile acids derivatives 2b-e are readily accessed by slow evaporation from selected solvents. A variety of steroidal scaffolds were found and elucidated by SXRD studies. The crystal packing of the title compounds are dominated by hydrogen-bonding interactions established between differently positioned acetyl protecting groups, which in the case of 2b and 2e take advantage of the facial amphiphilicity producing two novel steroidal supramolecular self-assemblies combining π-π and strong facial interactions. Thus, these crystalline arrays of side chain modified bile acids represent promising scaffolds for research and implementation in biomolecular materials or inclusion phenomena.

  19. An Analysis of Group-Oriented Contingencies and Associated Side Effects in Preschool Children

    ERIC Educational Resources Information Center

    Payne, Steven W.; Dozier, Claudia L.; Briggs, Adam M.; Newquist, Matthew H.

    2017-01-01

    Group-oriented contingencies are arranged to target the behavior of a group of people simultaneously. Overall, group-oriented contingencies have been shown to be effective in both decreasing problem behavior and increasing appropriate behavior. However, results are mixed regarding which type(s) of group-oriented contingency is most effective for…

  20. New pyridinium-based fluorescent dyes: A comparison of symmetry and side-group effects on G-Quadruplex DNA binding selectivity and application in live cell imaging.

    PubMed

    Lu, Yu-Jing; Hu, Dong-Ping; Zhang, Kun; Wong, Wing-Leung; Chow, Cheuk-Fai

    2016-07-15

    A series of C1-, C2-and C3-symmetric pyridinium conjugates with different styrene-like side groups were synthesized and were utilized as G-quadruplex selective fluorescent probes. The new compounds were well-characterized. Their selectivity, sensitivity, and stability towards G-quadruplex were studied by fluorescence titration, native PAGE experiments, FRET and circular dichroism (CD) analyses. These new compounds investigated in the fluorescence assays were preferentially bound with G-quadruplex DNA compared with other type of nucleic acids and it is fascinating to realize the effects of molecular symmetry and associated side groups showing unexpectedly great influence on the fluorescent signal enhancement for the discrimination of G-quadruplexes DNA from other nucleic acids. This may correlate with the pocket symmetry and shape of the G-quadruplex DNA inherently. Among the compounds, a C2-symmetric dye (2,6-bis-((E)-2-(1H-indol-3-yl)-vinyl)-1-methylpyridin-1-ium iodide) with indolyl-groups substituted was screened out from the series giving the best selectivity and sensitivity towards G-quadruplexes DNA, particularly telo21, due to its high equilibrium binding constant (K=2.17×10(5)M(-1)). In addition, the limit of detection (LOD) of the dye to determine telo21 DNA in bioassays was found as low as 33nM. The results of the study give insight and certain crucial factors, such as molecular symmetry and the associated side groups, on developing of effective fluorescent dyes for G-quadruplex DNA applications including G-quadruplex structure stabilization, biosensing and clinical applications. The compound was also demonstrated as a very selective G-quadruplex fluorescent agent for living cell staining and imaging.

  1. Protein Crosslinking by Genetically Encoded Noncanonical Amino Acids with Reactive Aryl Carbamate Side Chains.

    PubMed

    Xuan, Weimin; Shao, Sida; Schultz, Peter G

    2017-04-03

    The use of genetically encoded noncanonical amino acids (ncAAs) to construct crosslinks within or between proteins has emerged as a useful method to enhance protein stability, investigate protein-protein interactions, and improve the pharmacological properties of proteins. We report ncAAs with aryl carbamate side chains (PheK and FPheK) that can react with proximal nucleophilic residues to form intra- or intermolecular protein crosslinks. We evolved a pyrrolysyl-tRNA synthetase that incorporates site-specifically PheK and FPheK into proteins in both E. coli and mammalian cells. PheK and FPheK when incorporated into proteins showed good stability during protein expression and purification. FPheK reacted with adjacent Lys, Cys, and Tyr residues in thioredoxin in high yields. In addition, crosslinks could be formed between FPheK and Lys residue of two interacting proteins, including the heavy chain and light chain of an antibody Fab.

  2. (-)-UB006: A new fatty acid synthase inhibitor and cytotoxic agent without anorexic side effects.

    PubMed

    Makowski, Kamil; Mir, Joan Francesc; Mera, Paula; Ariza, Xavier; Asins, Guillermina; Hegardt, Fausto G; Herrero, Laura; García, Jordi; Serra, Dolors

    2017-05-05

    C75 is a synthetic anticancer drug that inhibits fatty acid synthase (FAS) and shows a potent anorexigenic side effect. In order to find new cytotoxic compounds that do not impact food intake, we synthesized a new family of C75 derivatives. The most promising anticancer compound among them was UB006 ((4SR,5SR)-4-(hydroxymethyl)-3-methylene-5-octyldihydrofuran-2(3H)-one). The effects of this compound on cytotoxicity, food intake and body weight were studied in UB006 racemic mixture and in both its enantiomers separately. The results showed that both enantiomers inhibit FAS activity and have potent cytotoxic effects in several tumour cell lines, such as the ovarian cell cancer line OVCAR-3. The (-)-UB006 enantiomer's cytotoxic effect on OVCAR-3 was 40-fold higher than that of racemic C75, and 2- and 38-fold higher than that of the racemic mixture and its opposite enantiomer, respectively. This cytotoxic effect on the OVCAR-3 cell line involves mechanisms that reduce mitochondrial respiratory capacity and ATP production, DDIT4/REDD1 upregulation, mTOR activity inhibition, and caspase-3 activation, resulting in apoptosis. In addition, central and peripheral administration of (+)-UB006 or (-)-UB006 into rats and mice did not affect food intake or body weight. Altogether, our data support the discovery of a new potential anticancer compound (-)-UB006 that has no anorexigenic side effects.

  3. Tuning the role of charge-transfer states in intramolecular singlet exciton fission through side-group engineering.

    PubMed

    Lukman, Steven; Chen, Kai; Hodgkiss, Justin M; Turban, David H P; Hine, Nicholas D M; Dong, Shaoqiang; Wu, Jishan; Greenham, Neil C; Musser, Andrew J

    2016-12-07

    Understanding the mechanism of singlet exciton fission, in which a singlet exciton separates into a pair of triplet excitons, is crucial to the development of new chromophores for efficient fission-sensitized solar cells. The challenge of controlling molecular packing and energy levels in the solid state precludes clear determination of the singlet fission pathway. Here, we circumvent this difficulty by utilizing covalent dimers of pentacene with two types of side groups. We report rapid and efficient intramolecular singlet fission in both molecules, in one case via a virtual charge-transfer state and in the other via a distinct charge-transfer intermediate. The singlet fission pathway is governed by the energy gap between singlet and charge-transfer states, which change dynamically with molecular geometry but are primarily set by the side group. These results clearly establish the role of charge-transfer states in singlet fission and highlight the importance of solubilizing groups to optimize excited-state photophysics.

  4. Tuning the role of charge-transfer states in intramolecular singlet exciton fission through side-group engineering

    NASA Astrophysics Data System (ADS)

    Lukman, Steven; Chen, Kai; Hodgkiss, Justin M.; Turban, David H. P.; Hine, Nicholas D. M.; Dong, Shaoqiang; Wu, Jishan; Greenham, Neil C.; Musser, Andrew J.

    2016-12-01

    Understanding the mechanism of singlet exciton fission, in which a singlet exciton separates into a pair of triplet excitons, is crucial to the development of new chromophores for efficient fission-sensitized solar cells. The challenge of controlling molecular packing and energy levels in the solid state precludes clear determination of the singlet fission pathway. Here, we circumvent this difficulty by utilizing covalent dimers of pentacene with two types of side groups. We report rapid and efficient intramolecular singlet fission in both molecules, in one case via a virtual charge-transfer state and in the other via a distinct charge-transfer intermediate. The singlet fission pathway is governed by the energy gap between singlet and charge-transfer states, which change dynamically with molecular geometry but are primarily set by the side group. These results clearly establish the role of charge-transfer states in singlet fission and highlight the importance of solubilizing groups to optimize excited-state photophysics.

  5. Absence of hematological side effects in acute and subacute nasal dosing of erythropoietin with a low content of sialic acid.

    PubMed

    Lagarto, Alicia; Bueno, Viviana; Guerra, Isbel; Valdés, Odalys; Couret, Micaela; López, Raisel; Vega, Yamile

    2011-09-01

    The use of human recombinant erythropoietin (EPO) as a neuroprotective agent is limited due to its hematological side effects. An erythropoietin along with a low content of sialic acid (rhEPOb), similar to that produced in the brain during hypoxia, may be used as a neuroprotective agent without risk of thrombotic events. The objective of this investigation was to assess the toxicological potential of a nasal formulation with rhEPOb in acute, subacute and nasal irritation assays in rats. Healthy Wistar rats (Cenp:Wistar) were used for the assays. In an irritation test, animals received 15 μl of rhEPOb into the right nostril. Rats were sacrificed after 24 h and slides of the nasal mucosa tissues were examined. Control and treated groups showed signs of a minimal irritation consisting of week edema and vascular congestion in all animals. In the acute toxicity test, the dose of 47,143 UI/kg was administered by nasal route. Hematological patterns, body weight, relative organ weight, and organ integrity were not affected by single dosing with rhEPOb. In the subacute toxicity test, Wistar rats of both sexes received 6,600 UI/kg/day for 14 days. The toxicological endpoints examined included animal body weight, food consumption, hematological and biochemical patterns, selected tissue weights, and histopathological examinations. An increase of lymphocytes was observed in males that was considered to reflect an immune response to treatment. Histopathological examination of organs and tissues did not reveal treatment-induced changes. The administration of rhEPOb at daily doses of 6,600 UI/kg during 14 days did not produce hematological side effects. These results suggest that rhEPOb could offer the same neuroprotection as EPO, without hematological side effects.

  6. Microbial biodegradation of aromatic alkanoic naphthenic acids is affected by the degree of alkyl side chain branching

    PubMed Central

    Johnson, Richard J; Smith, Ben E; Sutton, Paul A; McGenity, Terry J; Rowland, Steven J; Whitby, Corinne

    2011-01-01

    Naphthenic acids (NAs) occur naturally in oil sands and enter the environment through natural and anthropogenic processes. NAs comprise toxic carboxylic acids that are difficult to degrade. Information on NA biodegradation mechanisms is limited, and there are no studies on alkyl branched aromatic alkanoic acid biodegradation, despite their contribution to NA toxicity and recalcitrance. Increased alkyl side chain branching has been proposed to explain NA recalcitrance. Using soil enrichments, we examined the biodegradation of four aromatic alkanoic acid isomers that differed in alkyl side chain branching: (4′-n-butylphenyl)-4-butanoic acid (n-BPBA, least branched); (4′-iso-butylphenyl)-4-butanoic acid (iso-BPBA); (4′-sec-butylphenyl)-4-butanoic acid (sec-BPBA) and (4′-tert-butylphenyl)-4-butanoic acid (tert-BPBA, most branched). n-BPBA was completely metabolized within 49 days. Mass spectral analysis confirmed that the more branched isomers iso-, sec- and tert-BPBA were transformed to their butylphenylethanoic acid (BPEA) counterparts at 14 days. The BPEA metabolites were generally less toxic than BPBAs as determined by Microtox assay. n-BPEA was further transformed to a diacid, showing that carboxylation of the alkyl side chain occurred. In each case, biodegradation of the carboxyl side chain proceeded through beta-oxidation, which depended on the degree of alkyl side chain branching, and a BPBA degradation pathway is proposed. Comparison of 16S rRNA gene sequences at days 0 and 49 showed an increase and high abundance at day 49 of Pseudomonas (sec-BPBA), Burkholderia (n-, iso-, tert-BPBA) and Sphingomonas (n-, sec-BPBA). PMID:20962873

  7. Microbial biodegradation of aromatic alkanoic naphthenic acids is affected by the degree of alkyl side chain branching.

    PubMed

    Johnson, Richard J; Smith, Ben E; Sutton, Paul A; McGenity, Terry J; Rowland, Steven J; Whitby, Corinne

    2011-03-01

    Naphthenic acids (NAs) occur naturally in oil sands and enter the environment through natural and anthropogenic processes. NAs comprise toxic carboxylic acids that are difficult to degrade. Information on NA biodegradation mechanisms is limited, and there are no studies on alkyl branched aromatic alkanoic acid biodegradation, despite their contribution to NA toxicity and recalcitrance. Increased alkyl side chain branching has been proposed to explain NA recalcitrance. Using soil enrichments, we examined the biodegradation of four aromatic alkanoic acid isomers that differed in alkyl side chain branching: (4'-n-butylphenyl)-4-butanoic acid (n-BPBA, least branched); (4'-iso-butylphenyl)-4-butanoic acid (iso-BPBA); (4'-sec-butylphenyl)-4-butanoic acid (sec-BPBA) and (4'-tert-butylphenyl)-4-butanoic acid (tert-BPBA, most branched). n-BPBA was completely metabolized within 49 days. Mass spectral analysis confirmed that the more branched isomers iso-, sec- and tert-BPBA were transformed to their butylphenylethanoic acid (BPEA) counterparts at 14 days. The BPEA metabolites were generally less toxic than BPBAs as determined by Microtox assay. n-BPEA was further transformed to a diacid, showing that carboxylation of the alkyl side chain occurred. In each case, biodegradation of the carboxyl side chain proceeded through beta-oxidation, which depended on the degree of alkyl side chain branching, and a BPBA degradation pathway is proposed. Comparison of 16S rRNA gene sequences at days 0 and 49 showed an increase and high abundance at day 49 of Pseudomonas (sec-BPBA), Burkholderia (n-, iso-, tert-BPBA) and Sphingomonas (n-, sec-BPBA).

  8. Temporal characteristics of polarization holographic gratings formed in a photosensitive polymeric film containing N-benzylideneaniline derivative side groups

    NASA Astrophysics Data System (ADS)

    Sasaki, Tomoyuki; Shoho, Takashi; Noda, Kohei; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2014-04-01

    A polarization holographic grating was recorded in a transparent thin film formed from polymethacrylate with N-benzylideneaniline (NBA) derivative side groups. We measured the real time diffraction properties. The data were analyzed based on a theoretical model that accounted for the distribution of optical anisotropy caused by molecular reorientation as well as for surface relief (SR) deformation caused by molecular motion. Optical anisotropy rapidly increased and then slowly decreased, with increasing recording time. This phenomenon was described based on photoisomerization and photocleavage reactions of the NBA side groups. SR deformation was also induced in the film by polarization holographic recording, without any subsequent processes. The photoinduced optical anisotropy and SR deformation were retained after the recording was turned off.

  9. Temporal characteristics of polarization holographic gratings formed in a photosensitive polymeric film containing N-benzylideneaniline derivative side groups

    SciTech Connect

    Sasaki, Tomoyuki Shoho, Takashi; Noda, Kohei; Ono, Hiroshi; Kawatsuki, Nobuhiro

    2014-04-21

    A polarization holographic grating was recorded in a transparent thin film formed from polymethacrylate with N-benzylideneaniline (NBA) derivative side groups. We measured the real time diffraction properties. The data were analyzed based on a theoretical model that accounted for the distribution of optical anisotropy caused by molecular reorientation as well as for surface relief (SR) deformation caused by molecular motion. Optical anisotropy rapidly increased and then slowly decreased, with increasing recording time. This phenomenon was described based on photoisomerization and photocleavage reactions of the NBA side groups. SR deformation was also induced in the film by polarization holographic recording, without any subsequent processes. The photoinduced optical anisotropy and SR deformation were retained after the recording was turned off.

  10. Are Student Groups Dysfunctional? Perspectives from Both Sides of the Classroom

    ERIC Educational Resources Information Center

    Chapman, Kenneth J.; Meuter, Matthew L.; Toy, Daniel; Wright, Lauren K.

    2010-01-01

    In today's business world, the ability to work efficiently and effectively in a team is mandatory to a business student's success. Many employers rank "ability to work with a group" as one of the most important attributes for hiring business school graduates. Although an abundance of research has investigated group processes and dynamics during…

  11. Benzylidene Acetal Protecting Group as Carboxylic Acid Surrogate: Synthesis of Functionalized Uronic Acids and Sugar Amino Acids.

    PubMed

    Banerjee, Amit; Senthilkumar, Soundararasu; Baskaran, Sundarababu

    2016-01-18

    Direct oxidation of the 4,6-O-benzylidene acetal protecting group to C-6 carboxylic acid has been developed that provides an easy access to a wide range of biologically important and synthetically challenging uronic acid and sugar amino acid derivatives in good yields. The RuCl3 -NaIO4 -mediated oxidative cleavage method eliminates protection and deprotection steps and the reaction takes place under mild conditions. The dual role of the benzylidene acetal, as a protecting group and source of carboxylic acid, was exploited in the efficient synthesis of six-carbon sialic acid analogues and disaccharides bearing uronic acids, including glycosaminoglycan analogues.

  12. Large birefringence and polarization holographic gratings formed in photocross-linkable polymer liquid crystals comprising bistolane mesogenic side groups

    SciTech Connect

    Emoto, Akira; Matsumoto, Taro; Shioda, Tatsutoshi; Ono, Hiroshi; Yamashita, Ayumi; Kawatsuki, Nobuhiro

    2009-10-01

    Polarization gratings with large birefringence are formed in photoreactive polymer liquid crystals with bistolane moiety and terminal cinnamic acid moiety by the use of polarized ultraviolet interference light and subsequent annealing. The polarized ultraviolet light causes the axis-selective photoreaction between the cinnamic acid groups and subsequent annealing induce the reorientation of peripheral molecules without cross-linking along the cross-linked groups. Long bistolane mesogenic moiety exhibits large birefringence in comparison with a biphenyl mesogenic moiety, the value of the induced birefringence in the bistolane mesogenic liquid crystalline (LC) polymer is strongly dependent on both the grating constant and the wavelength of the reconstruction light.

  13. Nucleic acid chemistry in the organic phase: from functionalized oligonucleotides to DNA side chain polymers.

    PubMed

    Liu, Kai; Zheng, Lifei; Liu, Qing; de Vries, Jan Willem; Gerasimov, Jennifer Y; Herrmann, Andreas

    2014-10-08

    DNA-incorporating hydrophobic moieties can be synthesized by either solid-phase or solution-phase coupling. On a solid support the DNA is protected, and hydrophobic units are usually attached employing phosphoramidite chemistry involving a DNA synthesizer. On the other hand, solution coupling in aqueous medium results in low yields due to the solvent incompatibility of DNA and hydrophobic compounds. Hence, the development of a general coupling method for producing amphiphilic DNA conjugates with high yield in solution remains a major challenge. Here, we report an organic-phase coupling strategy for nucleic acid modification and polymerization by introducing a hydrophobic DNA-surfactant complex as a reactive scaffold. A remarkable range of amphiphile-DNA structures (DNA-pyrene, DNA-triphenylphosphine, DNA-hydrocarbon, and DNA block copolymers) and a series of new brush-type DNA side-chain homopolymers with high DNA grafting density are produced efficiently. We believe that this method is an important breakthrough in developing a generalized approach to synthesizing functional DNA molecules for self-assembly and related technological applications.

  14. Differentiating amino acid residues and side chain orientations in peptides using scanning tunneling microscopy.

    PubMed

    Claridge, Shelley A; Thomas, John C; Silverman, Miles A; Schwartz, Jeffrey J; Yang, Yanlian; Wang, Chen; Weiss, Paul S

    2013-12-11

    Single-molecule measurements of complex biological structures such as proteins are an attractive route for determining structures of the large number of important biomolecules that have proved refractory to analysis through standard techniques such as X-ray crystallography and nuclear magnetic resonance. We use a custom-built low-current scanning tunneling microscope to image peptide structures at the single-molecule scale in a model peptide that forms β sheets, a structural motif common in protein misfolding diseases. We successfully differentiate between histidine and alanine amino acid residues, and further differentiate side chain orientations in individual histidine residues, by correlating features in scanning tunneling microscope images with those in energy-optimized models. Beta sheets containing histidine residues are used as a model system due to the role histidine plays in transition metal binding associated with amyloid oligomerization in Alzheimer's and other diseases. Such measurements are a first step toward analyzing peptide and protein structures at the single-molecule level.

  15. D-Side: A Facility and Workforce Planning Group Multi-criteria Decision Support System for Johnson Space Center

    NASA Technical Reports Server (NTRS)

    Tavana, Madjid

    2005-01-01

    "To understand and protect our home planet, to explore the universe and search for life, and to inspire the next generation of explorers" is NASA's mission. The Systems Management Office at Johnson Space Center (JSC) is searching for methods to effectively manage the Center's resources to meet NASA's mission. D-Side is a group multi-criteria decision support system (GMDSS) developed to support facility decisions at JSC. D-Side uses a series of sequential and structured processes to plot facilities in a three-dimensional (3-D) graph on the basis of each facility alignment with NASA's mission and goals, the extent to which other facilities are dependent on the facility, and the dollar value of capital investments that have been postponed at the facility relative to the facility replacement value. A similarity factor rank orders facilities based on their Euclidean distance from Ideal and Nadir points. These similarity factors are then used to allocate capital improvement resources across facilities. We also present a parallel model that can be used to support decisions concerning allocation of human resources investments across workforce units. Finally, we present results from a pilot study where 12 experienced facility managers from NASA used D-Side and the organization's current approach to rank order and allocate funds for capital improvement across 20 facilities. Users evaluated D-Side favorably in terms of ease of use, the quality of the decision-making process, decision quality, and overall value-added. Their evaluations of D-Side were significantly more favorable than their evaluations of the current approach. Keywords: NASA, Multi-Criteria Decision Making, Decision Support System, AHP, Euclidean Distance, 3-D Modeling, Facility Planning, Workforce Planning.

  16. Synthesis of a Homologous Series of Side Chain Extended Orthogonally-Protected Aminooxy-Containing Amino Acids

    PubMed Central

    Liu, Fa; Thomas, Joshua; Burke, Terrence R.

    2008-01-01

    Practical methodology is reported for the synthesis of a homologous series of side chain extended amino acids containing aminooxy functionality bearing orthogonal protection suitable for Fmoc peptide synthesis. These reagents may be useful for the preparation of libraries containing fragments joined by peptide linkers. PMID:19122755

  17. Another side of the oxazaphospholidine oxide chiral ortho-directing group.

    PubMed

    Martins, Nelson; Mateus, Nuno; Vinci, Daniele; Saidi, Ourida; Brigas, Amadeu; Bacsa, John; Xiao, Jianliang

    2012-05-28

    A new ferrocenyl oxazaphospholidine oxide 3 was synthesized together with its P-epimer 2 in the reaction of ferrocene lithium with phosphoramidite chloride 1. 3 was successfully derivatized into planar chiral 1,2-ferrocenes, including phosphine ligands, via highly diastereoselective ortho-lithiation and subsequent functionalization; these compounds display opposite planar chirality to those obtained from 2. Some of these 1,2-ferrocenes were further lithiated, allowing for the introduction of a free phosphine group at the oxazaphospholidine ring. The X-ray structures of the compounds 2 and 3 as well as those of the new 1,2-ferrocenes 4 and 7 have been determined.

  18. Tuning the role of charge-transfer states in intramolecular singlet exciton fission through side-group engineering

    PubMed Central

    Lukman, Steven; Chen, Kai; Hodgkiss, Justin M.; Turban, David H. P.; Hine, Nicholas D. M.; Dong, Shaoqiang; Wu, Jishan; Greenham, Neil C.; Musser, Andrew J.

    2016-01-01

    Understanding the mechanism of singlet exciton fission, in which a singlet exciton separates into a pair of triplet excitons, is crucial to the development of new chromophores for efficient fission-sensitized solar cells. The challenge of controlling molecular packing and energy levels in the solid state precludes clear determination of the singlet fission pathway. Here, we circumvent this difficulty by utilizing covalent dimers of pentacene with two types of side groups. We report rapid and efficient intramolecular singlet fission in both molecules, in one case via a virtual charge-transfer state and in the other via a distinct charge-transfer intermediate. The singlet fission pathway is governed by the energy gap between singlet and charge-transfer states, which change dynamically with molecular geometry but are primarily set by the side group. These results clearly establish the role of charge-transfer states in singlet fission and highlight the importance of solubilizing groups to optimize excited-state photophysics. PMID:27924819

  19. K+ conductance modified by a titratable group accessible to protons from the intracellular side of the squid axon membrane.

    PubMed Central

    Wanke, E; Carbone, E; Testa, P L

    1979-01-01

    In the range of pH examined (5.2-10), variations of internal pH from high to low values result in a reversible decrease of the conductance of the open K channels, without significantly affecting the kinetics parameters. A linear plot of the conductance versus internal pH suggests the existence of a titratable group that has an apparent pKa of about 6.9, and that is accessible to protons only from the intracellular side of the membrane. PMID:45399

  20. Gas-phase reactivity of carboxylic acid functional groups with carbodiimides.

    PubMed

    Prentice, Boone M; Gilbert, Joshua D; Stutzman, John R; Forrest, William P; McLuckey, Scott A

    2013-01-01

    Gas-phase modification of carboxylic acid functionalities is performed via ion/ion reactions with carbodiimide reagents [N-cyclohexyl-N'-(2-morpholinoethyl)carbodiimide (CMC) and [3-(3-Ethylcarbodiimide-1-yl)propyl]trimethylaminium (ECPT)]. Gas-phase ion/ion covalent chemistry requires the formation of a long-lived complex. In this instance, the complex is stabilized by an electrostatic interaction between the fixed charge quaternary ammonium group of the carbodiimide reagent cation and the analyte dianion. Subsequent activation results in characteristic loss of an isocyanate derivative from one side of the carbodiimide functionality, a signature for this covalent chemistry. The resulting amide bond is formed on the analyte at the site of the original carboxylic acid. Reactions involving analytes that do not contain available carboxylic acid groups (e.g., they have been converted to sodium salts) or reagents that do not have the carbodiimide functionality do not undergo a covalent reaction. This chemistry is demonstrated using PAMAM generation 0.5 dendrimer, ethylenediaminetetraacetic acid (EDTA), and the model peptide DGAILDGAILD. This work demonstrates the selective gas-phase covalent modification of carboxylic acid functionalities.

  1. Understanding the effect of side groups in ionic liquids on carbon-capture properties: a combined experimental and theoretical effort

    SciTech Connect

    Yan, Fangyong; Lartey, Michael; Damodaran, Krishnan; Albenze, Erik; Thompson, Robert L.; Kim, Jihan; Harancyzk, Maciel; Nulwala, Hunaid B.; Luebke, David R.; Smit, Berend

    2013-01-01

    Ionic liquids are an emerging class of materials with applications in a variety of fields. Steady progress has been made in the creation of ionic liquids tailored to specific applications. However, the understanding of the underlying structure–property relationships has been slower to develop. As a step in the effort to alleviate this deficiency, the influence of side groups on ionic liquid properties has been studied through an integrated approach utilizing synthesis, experimental determination of properties, and simulation techniques. To achieve this goal, a classical force field in the framework of OPLS/Amber force fields has been developed to predict ionic liquid properties accurately. Cu(I)-catalyzed click chemistry was employed to synthesize triazolium-based ionic liquids with diverse side groups. Values of densities were predicted within 3% of experimental values, whereas self-diffusion coefficients were underestimated by about an order of magnitude though the trends were in excellent agreement, the activation energy calculated in simulation correlates well with experimental values. The predicted Henry coefficient for CO{sub 2} solubility reproduced the experimentally observed trends. This study highlights the importance of integrating experimental and computational approaches in property prediction and materials development, which is not only useful in the development of ionic liquids for CO{sub 2} capture but has application in many technological fields.

  2. Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 1. Minor structures

    USGS Publications Warehouse

    Leenheer, J.A.; Wershaw, R. L.; Reddy, M.M.

    1995-01-01

    An investigation of the strong-acid characteristics (pKa 3.0 or less) of fulvic acid from the Suwannee River, Georgia, was conducted. Quantitative determinations were made for amino acid and sulfur-containing acid structures, oxalate half-ester structures, malonic acid structures, keto acid structures, and aromatic carboxyl-group structures. These determinations were made by using a variety of spectrometric (13C-nuclear magnetic resonance, infrared, and ultraviolet spectrometry) and titrimetric characterizations on fulvic acid or fulvic acid samples that were chemically derivatized to indicate certain functional groups. Only keto acid and aromatic carboxyl-group structures contributed significantly to the strong-acid characteristics of the fulvic acid; these structures accounted for 43% of the strong-acid acidity. The remaining 57% of the strong acids are aliphatic carboxyl groups in unusual and/or complex configurations for which limited model compound data are available.

  3. THERMAL AND SPECTROSCOPIC ANALYSES OF NEXT GENERATION CAUSTIC SIDE SOLVENT EXTRACTION SOLVENT CONTACTED WITH 3, 8, AND 16 MOLAR NITRIC ACID

    SciTech Connect

    Fondeur, F.; Fink, S.

    2011-09-30

    A new solvent system referred to as Next Generation Solvent or NGS, has been developed at Oak Ridge National Laboratory for the removal of cesium from alkaline solutions in the Caustic Side Solvent Extraction process. NGS is proposed for deployment at MCU and at the Salt Waste Processing Facility. This work investigated the chemical compatibility between NGS and 16 M, 8 M, and 3 M nitric acid from contact that may occur in handling of analytical samples from MCU or, for 3 M acid, which may occur during contactor cleaning operations at MCU. This work shows that reactions occurred between NGS components and the high molarity nitric acid. In the case of 16 M and 8 M nitric acid, initially organo-nitrate groups are generated and attach to the modifier and that with time oxidation reactions convert the modifier into a tarry substance with gases (NO{sub x} and possibly CO) evolving. Calorimetric analysis of the organonitrate revealed the reaction products are not explosive nor will they deflagrate. NGS exposure to 3 M nitric acid resulted in much slower reaction kinetics and that the generated products were not energetic. We recommended conducting Accelerated Rate calorimetry on the materials generated in the 16 M and 8 M nitric acid test. Also, we recommend continue monitoring of the samples contacting NGS with 3 M nitric acid.

  4. Solvation free energies of amino acid side chain analogs for common molecular mechanics water models

    NASA Astrophysics Data System (ADS)

    Shirts, Michael R.; Pande, Vijay S.

    2005-04-01

    Quantitative free energy computation involves both using a model that is sufficiently faithful to the experimental system under study (accuracy) and establishing statistically meaningful measures of the uncertainties resulting from finite sampling (precision). In order to examine the accuracy of a range of common water models used for protein simulation for their solute/solvent properties, we calculate the free energy of hydration of 15 amino acid side chain analogs derived from the OPLS-AA parameter set with the TIP3P, TIP4P, SPC, SPC/E, TIP3P-MOD, and TIP4P-Ew water models. We achieve a high degree of statistical precision in our simulations, obtaining uncertainties for the free energy of hydration of 0.02-0.06kcal/mol, equivalent to that obtained in experimental hydration free energy measurements of the same molecules. We find that TIP3P-MOD, a model designed to give improved free energy of hydration for methane, gives uniformly the closest match to experiment; we also find that the ability to accurately model pure water properties does not necessarily predict ability to predict solute/solvent behavior. We also evaluate the free energies of a number of novel modifications of TIP3P designed as a proof of concept that it is possible to obtain much better solute/solvent free energetic behavior without substantially negatively affecting pure water properties. We decrease the average error to zero while reducing the root mean square error below that of any of the published water models, with measured liquid water properties remaining almost constant with respect to our perturbations. This demonstrates there is still both room for improvement within current fixed-charge biomolecular force fields and significant parameter flexibility to make these improvements. Recent research in computational efficiency of free energy methods allows us to perform simulations on a local cluster that previously required large scale distributed computing, performing four times as much

  5. A dynamic and ultrafast group delay tuning mechanism in two microcavities side-coupled with a waveguide system

    SciTech Connect

    Wang, Boyun; Wang, Tao Tang, Jian; Li, Xiaoming; Zhu, Youjiang

    2014-10-07

    We theoretically propose a dynamic and ultrafast group delay tuning mechanism in two microcavities side-coupled to a waveguide system through external optical pump beams. The optical Kerr effect modulation method is applied to improve tuning rate with response time of subpicoseconds or even femtoseconds. The group delay of an all-optical analog to electromagnetically induced transparency effect can be controlled by tuning either the frequency of photonic crystal microcavities or the propagation phase of line waveguide. Group delay is controlled between 5.88 and 70.98 ps by dynamically tuning resonant frequencies of the microcavities. Alternatively, the group delay is controlled between 1.86 and 12.08 ps by dynamically tuning the propagation phase of line waveguide. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and coupled-mode formalism. Results show a new direction toward microstructure integration optical pulse trapping and all-optical dynamical storage of light devices in optical communication and quantum information processing.

  6. Ascorbic acid oxidation of thiol groups from dithiotreitol is mediated by its conversion to dehydroascorbic acid

    PubMed Central

    Barbosa, Nilda B.V.; Lissner, Leandro A.; Klimaczewski, Cláudia V.; Colpo, Elisangela; Rocha, Joao B.T.

    2012-01-01

    The aim of the present study was to investigate whether the in vitro pro-oxidant effect of ascorbic acid towards thiol groups could be mediated by free radicals formed during its auto-oxidation and/or by a direct oxidation of -SH groups by its oxidized form (dehydroascorbic acid). This hypothesis was examined by measuring the rate of AA (ascorbic acid) oxidation in MOPS (3-morpholinepropanesulfonic acid buffer) and phosphate buffer (PB). Here we have used dithiothreitol (DTT) as model of vicinal thiol-containing enzymes, namely δ-aminolevulinate dehydratase. The rate of AA and DTT oxidation was more pronounced in the presence of PB than in the MOPS. AA oxidation induced by iron/EDTA complex was significantly reduced by addition of superoxide dismutase, catalase and DTT to the reaction medium. H2O2 alone did not stimulate the oxidation of AA; however, AA oxidation was enhanced significantly with the addition of crescent concentrations of iron. Conversely, in DTT oxidation assay (without AA) the addition of iron, EDTA and H2O2, did not promote the oxidation of -SH groups. Our findings suggest that in the presence of physiological concentrations of AA and thiols, the oxidation of -SH groups is mediated by AA conversion to dehydroascorbic acid with the participation of iron. Furthermore, free radical species formed during the auto-oxidation of AA apparently did not oxidize thiol groups to a significant extent. PMID:27847448

  7. Tetrahydrofuranyl and Tetrahydropyranyl Protection of Amino Acid Side-Chains Enables Synthesis of a Hydroxamate-Containing Aminoacylated tRNA†

    PubMed Central

    Lambert, Lester J.; Miller, Marvin J.; Huber, Paul W.

    2015-01-01

    The ability to specifically engineer metal binding sites into target proteins has far-reaching consequences ranging from the development of new biocatalysts and imaging reagents to the production of proteins with increased stability. We report the efficient tRNA-mediated incorporation of the hydroxamate containing amino acid, Nε-acetyl-Nε-hydroxy-l-lysine, into a transcription factor (TFIIIA). Because this amino acid is compact, hydrophilic, and uncharged at physiological pH, it should have little or no effect on protein folding or solubility. The Nε-hydroxy group of the hydroxamate is refractory to photodeprotection and required the identification of reagents for O-protection that are compatible with the synthesis of acylated tRNA. Tetrahydrofuranyl and tetrahydropyranyl O-protecting groups can be removed using mild acid conditions and allowed for an orthogonal protection strategy in which deprotection of the amino acid side chain precedes ligation of an acylated dinucleotide to a truncated suppressor tRNA. These protecting groups will provide a valuable alternative for O-protection, especially in cases where photodeprotection cannot be used. PMID:25562392

  8. Side-chain conformational thermodynamics of aspartic acid residue in the peptides and achatin-I in aqueous solution.

    PubMed

    Kimura, Tomohiro; Matubayasi, Nobuyuki; Nakahara, Masaru

    2004-02-01

    Sequence-position dependence of the side-chain conformational equilibrium of aspartic acid (Asp) residue is investigated for both model Asp peptides (di- to tetra-) and neuropeptide achatin-I (Gly--Phe-Ala-Asp) in aqueous solution. The trans-to-gauche conformational changes on the dihedral angle of C-C(alpha)-C(beta)-C are analyzed in terms of the standard free energy DeltaG(0), enthalpy DeltaH(0), and entropy -TDeltaS(0). The thermodynamic quantities are obtained by measuring the dihedral-angle-dependent vicinal (1)H-(1)H coupling constants in nuclear magnetic resonance over a wide temperature range. When the carboxyl groups of Asp are ionized, DeltaG(0) in the aqueous phase depends by approximately 1-2 kJ mol(-1) on the sequence position, whereas the energy change in the gas phase (absence of solvent) depends by tens of kJ mol(-1). Therefore, the weak position dependence of DeltaG(0) is a result of the compensation for the intramolecular effect by the hydration (= DeltaG(0)-). The DeltaH(0) and -TDeltaS(0) components, on the other hand, exhibit a notable trend at the C-terminus. The C-terminal DeltaH(0) is larger than the N- and nonterminal DeltaH(0) values due to the intramolecular repulsion between alpha- and beta-. The C-terminal -TDeltaS(0) is negative and larger in magnitude than the others, and an attractive solute-solvent interaction at the C-terminus serves as a structure breaker of the water solvent.

  9. Introduction of the (-)-berkelic acid side chain and assignment of the C-22 stereochemistry.

    PubMed

    Wu, Xiaoxing; Zhou, Jingye; Snider, Barry B

    2009-08-21

    A Kiyooka aldol condensation of an aldehyde with a trimethylsilyl ketene acetal and the oxazaborolidinone prepared from N-Ts-(S)-valine gives two of the four possible aldol adducts, which were oxidized and deprotected to complete the synthesis of (-)-berkelic acid and (-)-22-epi-berkelic acid. This synthesis establishes the absolute stereochemistry and assigns the stereochemistry at C-22. A biosynthetic pathway is proposed that is consistent with the known absolute stereochemistry at the quaternary carbon of spiciferone A, spicifernin, and berkelic acid and provides a simple explanation for the differing stereochemistry at C-18 and C-19 of spicifernin and berkelic acid.

  10. Structure-activity relationships of nonisomerizable derivatives of tamoxifen: importance of hydroxyl group and side chain positioning for biological activity.

    PubMed

    Murphy, C S; Parker, C J; McCague, R; Jordan, V C

    1991-03-01

    other substitutions produced either estrogenic compounds or less potent antiestrogens. The hydroxyl group appears to be critical to locate the alkyl aminoethoxy side chain in the correct position in the steroid-binding site to block estrogen action. Novel antiestrogens were identified that could have been predicted based upon earlier drug-receptor models for the ER.

  11. Morphology and electrochemical properties of perfluorosulfonic acid ionomers for vanadium flow battery applications: effect of side-chain length.

    PubMed

    Ding, Cong; Zhang, Huamin; Li, Xianfeng; Zhang, Hongzhang; Yao, Chuan; Shi, Dingqin

    2013-07-01

    Perfluorosulfonic acid ionomers (PFSI) with different side-chain lengths have been investigated with respect to their morphology and electrochemical properties in vanadium flow batteries (VFB). The results indicated that the membrane with the shortest side chains (SSC-M2) displayed small ion clusters and a low degree of hydrophobic-hydrophilic separation, which is favourable to reduce the cross-over of vanadium ions in the VFB. SSC-M2 shows a similar proton conductivity to Nafion, which carries longer ionic side chains but with much lower ion permeability. As a result, the VFB assembled with SSC-M2 exhibited a superior coulombic efficiency and a voltage efficiency close to that of Nafion115. In situ mass transfer revealed that SSC-M2 had a remarkably low degree of vanadium and water transfer across the membrane, which resulted in lower capacity fading than in the case of Nafion115. These results indicate that a membrane with short side chains is an ideal option in the fabrication of high-performance VFBs with low capacity loss.

  12. The effect of glutamic acid side chain on acidity constant of lysine in beta-sheet: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Sargolzaei, M.; Afshar, M.; Sadeghi, M. S.; Kavee, M.

    2014-07-01

    In this work, the possibility of proton transfer between side chain of lysine and glutamic acid in peptide of Glu--Ala-Lys+ was demonstrated using density functional theory (DFT). We have shown that the proton transfer takes place between side chain of glutamic and lysine residues through the hydrogen bond formation. The structures of transition state for proton transfer reaction were detected in gas and solution phases. Our kinetic studies show that the proton transfer reaction rate in gas phase is higher than solution phase. The ionization constant (p K a) value of lysine residue in peptide was estimated 1.039 which is lower than intrinsic p K a of lysine amino acid.

  13. Destruxin analogs: variations of the alpha-hydroxy acid side chain.

    PubMed

    Cavelier, F; Jacquier, R; Mercadier, J L; Verducci, J; Traris, M; Vey, A

    1997-08-01

    This work describes the synthesis of three destruxin E cyclodepsipeptidic analogs. These compounds have an identical amino acid sequence but differ by the nature of the hydroxy acid residue with is 2-hydroxy-3-phenylpropionic (Hpp), 2-hydroxy-5-trimethylsilyl-4-pentynoic (Hpy-TMS) and 2-hydroxy-4-pentynoic (Hpy) acid, respectively. The insecticidal properties on the Galleria mellonella larvae (paralysis and lethal effect) of these analogs are presented in comparison with the natural destruxin E. All these compounds have toxic effects, the most potent being Hpy that induces the same effect as destruxin E.

  14. Amino Acid Side Chains Buried along Intersubunit Interfaces in a Viral Capsid Preserve Low Mechanical Stiffness Associated with Virus Infectivity.

    PubMed

    Carrillo, Pablo José P; Medrano, María; Valbuena, Alejandro; Rodríguez-Huete, Alicia; Castellanos, Milagros; Pérez, Rebeca; Mateu, Mauricio G

    2017-02-28

    Single-molecule experimental techniques and theoretical approaches reveal that important aspects of virus biology can be understood in biomechanical terms at the nanoscale. A detailed knowledge of the relationship in virus capsids between small structural changes caused by single-point mutations and changes in mechanical properties may provide further physics-based insights into virus function; it may also facilitate the engineering of viral nanoparticles with improved mechanical behavior. Here, we used the minute virus of mice to undertake a systematic experimental study on the contribution to capsid stiffness of amino acid side chains at interprotein interfaces and the specific noncovalent interactions they establish. Selected side chains were individually truncated by introducing point mutations to alanine, and the effects on local and global capsid stiffness were determined using atomic force microscopy. The results revealed that, in the natural virus capsid, multiple, mostly hydrophobic, side chains buried along the interfaces between subunits preserve a comparatively low stiffness of most (S2 and S3) regions. Virtually no point mutation tested substantially reduced stiffness, whereas most mutations increased stiffness of the S2/S3 regions. This stiffening was invariably associated with reduced virus yields during cell infection. The experimental evidence suggests that a comparatively low stiffness at S3/S2 capsid regions may have been biologically selected because it facilitates capsid assembly, increasing infectious virus yields. This study demonstrated also that knowledge of individual amino acid side chains and biological pressures that determine the physical behavior of a protein nanoparticle may be used for engineering its mechanical properties.

  15. α-Ketoheterocycle Inhibitors of Fatty Acid Amide Hydrolase: Exploration of Conformational Constraints in the Acyl Side Chain

    PubMed Central

    Duncan, Katharine K.; Otrubova, Katerina; Boger, Dale L.

    2014-01-01

    A series of α-ketooxazoles containing heteroatoms embedded within conformational constraints in the C2 acyl side chain of 2 (OL-135) were synthesized and evaluated as inhibitors of fatty acid amide hydrolase (FAAH). The studies reveal that the installation of a heteroatom (O) in the conformational constraint is achievable, although the potency of these novel derivatives is reduced slightly relative to 2 and the analogous 1,2,3,4-tetrahydronaphthalene series. Interestingly, both enantiomers (R and S) of the candidate inhibitors bearing a chiral center adjacent to the electrophilic carbonyl were found to effectively inhibit FAAH. PMID:24690529

  16. Hydrated arrays of acidic surface groups as model systems for interfacial structure and mechanisms in PEMs.

    PubMed

    Roudgar, A; Narasimachary, S P; Eikerling, M

    2006-10-19

    We utilize ab initio quantum mechanical calculations in order to explore structural conformations and cooperative mechanisms at a minimally hydrated 2D array of flexible acidic surface groups. This system serves as a model for rationalizing interactions and correlations of protons and water with ionized side chains that are affixed to hydrophobic polymer aggregates in polymer electrolyte membranes (PEMs). The model exhibits two basic minimum energy configurations upon varying the separation of surface groups from 5 to 12 A. In the "upright" structure at small separation, surface groups are fully dissociated and oriented perpendicular to the basal plane. Together with hydronium ions (H3O+) they form a highly ordered network with long-range correlations. At larger separations we found the transition to a "tilted" structure with cluster-like conformation of surface groups. This structure retains only short-range correlations. Moreover, we investigated the strength of water binding to the minimally hydrated structures. At small separations between surface groups, an additional water molecule interacts only weakly with the minimally hydrated array (binding energy < 0.1 eV) while the energy needed to remove one water molecule exceeds 1 eV. This shows that the minimally hydrated systems are very stable. Ideally, these studies would expedite the design of cheap, highly performing PEMs for fuel cells, with a major focus on membranes that could operate stably at minimal hydration and elevated temperatures (>120 degrees C).

  17. Fatty acid methyl esters with two vicinal alkylthio side chains and their NMR characterization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The addition reaction of dimethyl disulfide (DMDS) to double bonds in alkenes and monounsaturated fatty acid esters in the presence of iodine or other catalysts to give bis(methylthio) derivatives has largely served analytical purposes in mass spectrometry with scattered reports on the addition of o...

  18. Energetics of side-chain snorkeling in transmembrane helices probed by nonproteinogenic amino acids.

    PubMed

    Öjemalm, Karin; Higuchi, Takashi; Lara, Patricia; Lindahl, Erik; Suga, Hiroaki; von Heijne, Gunnar

    2016-09-20

    Cotranslational translocon-mediated insertion of membrane proteins into the endoplasmic reticulum is a key process in membrane protein biogenesis. Although the mechanism is understood in outline, quantitative data on the energetics of the process is scarce. Here, we have measured the effect on membrane integration efficiency of nonproteinogenic analogs of the positively charged amino acids arginine and lysine incorporated into model transmembrane segments. We provide estimates of the influence on the apparent free energy of membrane integration (ΔGapp) of "snorkeling" of charged amino acids toward the lipid-water interface, and of charge neutralization. We further determine the effect of fluorine atoms and backbone hydrogen bonds (H-bonds) on ΔGapp These results help establish a quantitative basis for our understanding of membrane protein assembly in eukaryotic cells.

  19. Energetics of side-chain snorkeling in transmembrane helices probed by nonproteinogenic amino acids

    PubMed Central

    Öjemalm, Karin; Higuchi, Takashi; Lara, Patricia; Lindahl, Erik; Suga, Hiroaki

    2016-01-01

    Cotranslational translocon-mediated insertion of membrane proteins into the endoplasmic reticulum is a key process in membrane protein biogenesis. Although the mechanism is understood in outline, quantitative data on the energetics of the process is scarce. Here, we have measured the effect on membrane integration efficiency of nonproteinogenic analogs of the positively charged amino acids arginine and lysine incorporated into model transmembrane segments. We provide estimates of the influence on the apparent free energy of membrane integration (ΔGapp) of “snorkeling” of charged amino acids toward the lipid–water interface, and of charge neutralization. We further determine the effect of fluorine atoms and backbone hydrogen bonds (H-bonds) on ΔGapp. These results help establish a quantitative basis for our understanding of membrane protein assembly in eukaryotic cells. PMID:27601675

  20. Site-specific protonation kinetics of acidic side chains in proteins determined by pH-dependent carboxyl (13)C NMR relaxation.

    PubMed

    Wallerstein, Johan; Weininger, Ulrich; Khan, M Ashhar I; Linse, Sara; Akke, Mikael

    2015-03-04

    Proton-transfer dynamics plays a critical role in many biochemical processes, such as proton pumping across membranes and enzyme catalysis. The large majority of enzymes utilize acid-base catalysis and proton-transfer mechanisms, where the rates of proton transfer can be rate limiting for the overall reaction. However, measurement of proton-exchange kinetics for individual side-chain carboxyl groups in proteins has been achieved in only a handful of cases, which typically have involved comparative analysis of mutant proteins in the context of reaction network modeling. Here we describe an approach to determine site-specific protonation and deprotonation rate constants (kon and koff, respectively) of carboxyl side chains, based on (13)C NMR relaxation measurements as a function of pH. We validated the method using an extensively studied model system, the B1 domain of protein G, for which we measured rate constants koff in the range (0.1-3) × 10(6) s(-1) and kon in the range (0.6-300) × 10(9) M(-1) s(-1), which correspond to acid-base equilibrium dissociation constants (Ka) in excellent agreement with previous results determined by chemical shift titrations. Our results further reveal a linear free-energy relationship between log kon and pKa, which provides information on the free-energy landscape of the protonation reaction, showing that the variability among residues in these parameters arises primarily from the extent of charge stabilization of the deprotonated state by the protein environment. We find that side-chain carboxyls with extreme values of koff or kon are involved in hydrogen bonding, thus providing a mechanistic explanation for the observed stabilization of the protonated or deprotonated state.

  1. In situ amination and side group effect of multifunctional heterocyclic thione ligand toward discrete and polymeric cluster constructions.

    PubMed

    Hu, Sheng; Yu, Fang-Yong; Zhang, Peng; Lin, Dian-Rong

    2013-06-07

    Three metal complexes [Cu(I)6(atdm)6] (1), [Cu(I)(Hatd)(H2atd)] (2) and [H3O][Co(II)4Co(III)2Cl3(atd)6]·H2O (3) [atdm = 4-dimethylamino-6-anilino-1,3,5-triazine-2-thiolate, H2atd = 6-anilino-1,3,5-triazine-2,4-dithiol, atdH2 = 6-anilino-1,3,5-triazine-2,4(1H,3H)-dithione] have been solvothermally synthesized. The luminescent complexes 1 and 2 provide remarkable structural diversity depending on different reaction solutions. Complex 1 consists of a discrete pseudohexagonal prismatic [Cu6S6] core that can be described as two stacked, chair-shaped [Cu3S3] rings bound together by the C-N bridges of the atdm ligands, in which the atdm ligand was generated via in situ amination of H2atd in the presence of DMF solution. Whereas complex 2 is a 2D (4,4) net based on single node Cu(I) ions crystallized in acetonitrile, in which H2atd ligands exist in the thione form atdH2 and the partially deprotonated form atdH. Complex 3 has a two-fold interpenetrated (10,3)-a topological network based on unprecedented cobalt-centered trigonal-bipyramidal [Co6(atd)6] building blocks, linked by Cl(-) double-bridges and showing oriented effects of aniline side groups. IR spectra, elemental analyses and XRD analyses confirmed the phase-purities of the as-synthesized complexes. The photoluminescence properties of 1 and 2 in the solid state and the magnetic properties of 3 are investigated. A discussion of the crystal structures, as well as the coordination properties of the multifunctional sulfur-containing ligands upon different geometries of the central units, is also provided.

  2. Influence of the degree of unsaturation of the acyl side chain upon the interaction of analogues of 1-arachidonoylglycerol with monoacylglycerol lipase and fatty acid amide hydrolase.

    PubMed

    Vandevoorde, Séverine; Saha, Bijali; Mahadevan, Anu; Razdan, Raj K; Pertwee, Roger G; Martin, Billy R; Fowler, Christopher J

    2005-11-11

    Little is known as to the structural requirements of the acyl side chain for interaction of acylglycerols with monoacylglycerol lipase (MAGL), the enzyme chiefly responsible for the metabolism of the endocannabinoid 2-arachidonoylglycerol (2-AG) in the brain. In the present study, a series of twelve analogues of 1-AG (the more stable regioisomer of 2-AG) were investigated with respect to their ability to inhibit the metabolism of 2-oleoylglycerol by cytosolic and membrane-bound MAGL. In addition, the ability of the compounds to inhibit the hydrolysis of anandamide by fatty acid amide hydrolase (FAAH) was investigated. For cytosolic MAGL, compounds with 20 carbon atoms in the acyl chain and 2-5 unsaturated bonds inhibited the hydrolysis of 2-oleoylglycerol with similar potencies (IC50 values in the range 5.1-8.2 microM), whereas the two compounds with a single unsaturated bond were less potent (IC50 values 19 and 21 microM). The fully saturated analogue 1-monoarachidin did not inhibit the enzyme, whereas the lower side chain analogues 1-monopalmitin and 1-monomyristin inhibited the enzyme with IC50 values of 12 and 32 microM, respectively. The 22-carbon chain analogue of 1-AG was also potent (IC50 value 4.5 microM). Introduction of an alpha-methyl group for the C20:4, C20:3, and C22:4 compounds did not affect potency in a consistent manner. For the FAAH and the membrane-bound MAGL, there was no obvious relationship between the degree of unsaturation of the acyl side chain and the ability to inhibit the enzymes. It is concluded that increasing the number of unsaturated bonds on the acyl side chain of 1-AG from 1 to 5 has little effect on the affinity of acylglycerols for cytosolic MAGL.

  3. Characterization of novel perylene diimides containing aromatic amino acid side chains

    PubMed Central

    Farooqi, Mohammed J.; Penick, Mark A.; Burch, Jessica; Negrete, George R.; Brancaleon, Lorenzo

    2015-01-01

    Perylene diimide derivatives have attracted initial interest as industrial dyes. Recently, much attention has been focused on their strong π–π stacks resulting from the large PDI aromatic core. These PDI stacks have distinct optical properties, and provide informative models that could mimic light-harvesting systems and initial charge transfer typical of photosynthetic systems. The absorption property of PDI derivatives may be tuned from visible to near-infrared region by peripheral substitution. We have studied a new class of PDI derivatives with aryl substituents derived from the side chains of aromatic aminoacids (Tyrosine, Tryptophan and Phenylalanine). We have investigated their absorption and the fluorescence properties in a set of organic solvents and established their different tendencies to aggregate in solution despite their solubility. Most aggregation appears to be unordered. One PDI analogue (the one formed from Tyr) in Methanol, however, appears to form J-type aggregates. Based on our results the compounds appear to be promising for future investigations regarding the interaction of these dyes with biomolecules. PMID:26298679

  4. Fluorescence properties of a novel side-chain polymer based on polyamic acid

    NASA Astrophysics Data System (ADS)

    Lu, Jianmei; Yao, Shechun; Tang, Xiubo; Sun, Ming; Zhu, Xiulin

    2004-05-01

    The p-π conjugated polyamic acid (PAA) had been synthesized through 1,4-diaminoanthraquinone (DAAQ) and pyromellitic dianhydride (PMDA) under microwave irradiation. The graft PAAs were obtained by toluene-2,4-diisocyanate (TDI) derivatives having different straight-chain alkyl. The resulted graft polymers had good dissolution capabilities, film-forming capabilities and strong fluorescence. We investigated some factors influencing fluorescence performance on graft PAA and found that with increasing chain length of the straight-chain alkyl or increasing graft degree, the fluorescence intensity and quantum efficiency will be enhanced markedly.

  5. Side effects assessment in glicolyc acid peelings in patients with acne type I.

    PubMed

    Perić, Sanja; Bubanj, Maja; Bubanj, Saša; Jančić, Snežana

    2011-02-01

    Chemical peeling implies the application of a chemical agent to the skin, which causes controlled destruction of a part or the entire epidermis, with or without the dermis, leading to exfoliation and removal of superficial lesions, followed by regeneration of new epidermal and dermal tissues. The present study was directed toward safety concerns associated with superficial chemical peeling with glycolic acid (GA) in different concentrations at patients with acne tip I. A sample of 90 patients of either sex, aged between 17 to 21 years, were included in the study and submitted to superficial chemical peeling for acne vulgaris. The study lasted eight weeks and peeling sessions were carried out in each patient. Tolerance to the procedure and any undesirable effects noted during these sessions were recorded. For data statistical analysis and interpretation of results, software program "SPSS version 13" was used. Results were expressed through the descriptive statistics, as simple frequencies and percentages, while for establishing of statistically significant differences, in use was Friedman's test of significance. Almost all the patients tolerated the procedure well. Of totally 90 patients, only six, at the end of therapy experienced hard erythema, only ten, at the end of therapy experienced hard desquamation and only eleven, at the end of therapy experienced hard sensation of pulling of facial skin. Chemical peeling with glycolic acid is a well tolerated and safe treatment modality in acne type I.

  6. N-acetyl-L-aspartic acid-N'-methylamide with side-chain orientation capable of external hydrogen bonding . Backbone and side-chain folding, studied at the DFT level of quantum theory

    NASA Astrophysics Data System (ADS)

    Koo, J. C. P.; Chass, G. A.; Perczel, A.; Farkas, Ö.; Varro, A.; Torday, L. L.; Papp, J. Gy.; Csizmadia, I. G.

    2002-09-01

    In this study, we generated and analyzed the side-chain conformational potential energy hypersurfaces for each of the nine possible backbone conformers for N-acetyl-L-aspartic acid-N' methylamide. We found a total of 27 out of the 81 possible conformers optimized at the B3LYP/6-31G(d) level of theory. The relative energies, as well as the stabilization energies exerted by the side-chain on the backbone, have been calculated for each of the 27 optimized conformers at this level of theory. Various backbone-backbone (N H{\\cdot}{\\cdot}{\\cdot}O=C) and backbone-side-chain (N H{\\cdot}{\\cdot}{\\cdot}O=C; N H{\\cdot}{\\cdot}{\\cdot}OH) hydrogen bonds were analyzed. The appearance of the notoriously absent \\varepsilon_L backbone conformer may be attributed to such side-chain-backbone (SC/BB) and backbone-backbone (BB/BB) hydrogen bonds.

  7. Roles of the methyl and methylene groups of mercapto acids in the photoluminescence efficiency and carrier trapping dynamics of CdTe QDs.

    PubMed

    Chandra Sekhar, M; De, Apurba; Hossain, Sk Saddam; Samanta, Anunay

    2017-01-04

    Surface protection using an appropriate ligand is essential for controlling the size, stability and luminescence properties of the quantum dots (QDs). Though 3-mercaptopropanoic acid (3-MPA) is regarded as the most suitable protecting ligand among the mercapto acids for water soluble CdTe QDs, one receives a different picture from recent studies, which report a much higher luminescence efficiency of 3-mercaptobutyric acid (3-MBA) capped QDs compared with those capped by 3-MPA and attribute the observation to the influence of the side methyl group of mercapto acids. Herein we report the luminescence properties and carrier trapping dynamics of four different, but structurally related mercapto acid capped CdTe QDs prepared using a different method. The results show that these QDs are much more fluorescent than those prepared directly in an aqueous environment and surprisingly, no enhanced luminescence for the QDs capped by mercapto acids containing a side methyl group is observed. Ultrafast pump-probe measurements confirm these results in addition to providing insight into the carrier trapping dynamics of these systems. It is shown that our findings, which appear to be in conflict with the recent literature, can be rationalized and the exact role of the side methyl group of the mercapto acids can be understood by careful analysis of the results taking into consideration the difference in the methods of preparation of the QDs in the two cases.

  8. Conformational analysis of short polar side-chain amino-acids through umbrella sampling and DFT calculations.

    PubMed

    Ramos, Javier; Cruz, Victor L

    2016-11-01

    Molecular and quantum mechanics calculations were carried out in a series of tripeptides (GXG, where X = D, N and C) as models of the unfolded states of proteins. The selected central amino acids, especially aspartic acid (D) and asparagine (N) are known to present significant average conformations in partially allowed areas of the Ramachandran plot, which have been suggested to be important in unfolded protein regions. In this report, we present the calculation of the propensity values through an umbrella sampling procedure in combination with the calculation of the NMR J-coupling constants obtained by a DFT model. The experimental NMR observations can be reasonably explained in terms of a conformational distribution where PPII and β basins sum up propensities above 0.9. The conformational analysis of the side chain dihedral angle (χ1), along with the computation of (3)J(H(α)H(β)), revealed a preference for the g - and g + rotamers. These may be connected with the presence of intermolecular H-bonding and carbonyl-carbonyl interactions sampled in the PPII and β basins. Taking into account all those results, it can be established that these residues show a similar behavior to other amino acids in short peptides regarding backbone φ,ψ dihedral angle distribution, in agreement with some experimental analysis of capped dipeptides.

  9. Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 2. Major structures

    USGS Publications Warehouse

    Leenheer, J.A.; Wershaw, R. L.; Reddy, M.M.

    1995-01-01

    Polycarboxylic acid structures that account for the strong-acid characteristics (pKa1 near 2.0) were examined for fulvic acid from the Suwannee River. Studies of model compounds demonstrated that pKa values near 2.0 occur only if the ??-ether or ??-ester groups were in cyclic structures with two to three additional electronegative functional groups (carboxyl, ester, ketone, aromatic groups) at adjacent positions on the ring. Ester linkage removal by alkaline hydrolysis and destruction of ether linkages through cleavage and reduction with hydriodic acid confirmed that the strong carboxyl acidity in fulvic acid was associated with polycarboxylic ??-ether and ??-ester structures. Studies of hypothetical structural models of fulvic acid indicated possible relation of these polycarboxylic structures with the amphiphilic and metal-binding properties of fulvic acid.

  10. Poly(organophosphazenes) with azolylmethylphenoxy and pyridinoxy side groups to be used as proton exchange membranes in fuel cells

    NASA Astrophysics Data System (ADS)

    Ekanayake, Sujeewani K.

    2011-12-01

    Proton Exchange Membrane Fuel Cells (PEMFCs) are of great importance to many stationary and portable applications. The development of a more efficient, high-temperature tolerant membrane with a high protonic conductivity has become critical to the better performance of PEMFCs. Consequently, the focus of current research is more focused on synthesizing membranes which can function at a non-humidified high temperature environment. Because N-heterocycles such as azoles substituted on a polyphosphazene backbone have been found to be one of the best polymers in this regard, the focus of this dissertation is primarily on developing PEMs (proton exchange membranes) based on azole and pyridine substituted phosphazenes. In Chapter 1, an overview on PEMFCs as well as PEMs that have been synthesized to date is presented. The first part of the introduction is devoted to sulfonated fluorocarbon-based membrane, NafionRTM. Then the focus slowly shifts towards PEMs based on hydrocarbon polymers. The rest of Chapter 1 mainly revolves around polyphosphazene based PEMs. Chapter 2 describes the synthesis of trimeric, small-molecule, model compounds for high polymers. A series of hexakis(azolylmethylphenoxy)cyclotriphosphazenes where the azolyl groups are pyrazol, 1,2,4-triazol and 5-methyltetrazol and all three isomers of hexakis(pyridinoxy)cyclotriphosphazenes have been synthesized and characterized. The focus of Chapter 3 is on the synthesis of poly(dichlorophosphazene) by modifying a literature procedure reported by Wang (Macromolecules 2005, 38, 643--645) via one-pot in situ polycondensation. Chapter 3 also presents a preliminary study on ring opening polymerization. The focus of Chapter 4 is completely on the synthesis and characterization of azole and pyridine substituted polyphosphazenes. Chapter 5 includes film casting studies from both triazolphenol trimer and polymer to obtain corresponding composites and blends by mixing with commercially available poly(PMDA-ODA) amic acid

  11. UV-Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 2: selected applications.

    PubMed

    Antosiewicz, Jan M; Shugar, David

    In Part 2 we discuss application of several different types of UV-Vis spectroscopy, such as normal, difference, and second-derivative UV absorption spectroscopy, fluorescence spectroscopy, linear and circular dichroism spectroscopy, and Raman spectroscopy, of the side-chain of tyrosine residues in different molecular environments. We review the ways these spectroscopies can be used to probe complex protein structures.

  12. Side-Chain Conformational Thermodynamics of Aspartic Acid Residue in the Peptides and Achatin-I in Aqueous Solution

    PubMed Central

    Kimura, Tomohiro; Matubayasi, Nobuyuki; Nakahara, Masaru

    2004-01-01

    Sequence-position dependence of the side-chain conformational equilibrium of aspartic acid (Asp) residue is investigated for both model Asp peptides (di- to tetra-) and neuropeptide achatin-I (Gly-𝒟-Phe-Ala-Asp) in aqueous solution. The trans-to-gauche conformational changes on the dihedral angle of C–Cα–Cβ–C are analyzed in terms of the standard free energy ΔG0, enthalpy ΔH0, and entropy −TΔS0. The thermodynamic quantities are obtained by measuring the dihedral-angle-dependent vicinal 1H-1H coupling constants in nuclear magnetic resonance over a wide temperature range. When the carboxyl groups of Asp are ionized, ΔG0 in the aqueous phase depends by ∼1–2 kJ mol−1 on the sequence position, whereas the energy change \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\Delta}E_{{\\mathrm{gas}}}^{0}\\end{equation*}\\end{document} in the gas phase (absence of solvent) depends by tens of kJ mol−1. Therefore, the weak position dependence of ΔG0 is a result of the compensation for the intramolecular effect \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\Delta}E_{{\\mathrm{gas}}}^{0}\\end{equation*}\\end{document} by the hydration \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\Delta}G_{{\\mathrm{hyd}}}^{0}\\end{equation*}\\end{document} (= ΔG0–\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage

  13. Investigation of nonfouling polypeptides of poly(glutamic acid) with lysine side chains synthesized by EDC·HCl/HOBt chemistry.

    PubMed

    Yang, Qinghua; Li, Wenchen; Wang, Longgang; Wang, Guangzhi; Wang, Zhen; Liu, Lingyun; Chen, Shengfu

    2014-01-01

    Nonfouling polypeptides with homogenous alternating charges draw peoples' attentions for their potential capability in biodegradation. Homogenous glutamic acid (E) and lysine (K) polypeptides were proposed and synthesized before. In this work, a new polypeptide formed by poly(glutamic acid) with lysine side chains (poly(E)-K) was synthesized by facile EDC·HCl/HOBt chemistry and investigated. Results show that these polypeptides also have good nonspecific protein resistance determined by enzyme-linked immunosorbent assay. The lowest nonspecific adsorption of the model proteins, anti-IgG and fibrinogen (Fg), on the self-assembling monolayers (SAMs) surface of poly(E)-K was only 3.3 ± 1.8 and 4.4 ± 1.6%, respectively, when protein adsorption on tissue culture polystyrene surface was set as 100%. And, the relative nonspecific protein adsorption increases when the polypeptide molecular weight increases due to the repression of low density polymer brushes. Moreover, almost no obvious cytotoxicity and hemolytic activity in vitro were detected. This work suggests that polypeptides with various formats of homogenous balanced charges could achieve excellent nonspecific protein resistance, which might be the intrinsic reason for the coexistence of high concentration serum proteins in blood.

  14. Effects of new fish oil derivative on fatty acid phospholipid-membrane pattern in a group of Crohn's disease patients.

    PubMed

    Belluzzi, A; Brignola, C; Campieri, M; Camporesi, E P; Gionchetti, P; Rizzello, F; Belloli, C; De Simone, G; Boschi, S; Miglioli, M

    1994-12-01

    Fish oil has been recently proposed as a possible effective treatment in inflammatory bowel disease (IBD); however, a lot of annoying side effects (ie, belching, halitosis, diarrhea, etc) affect patient compliance. We carried out a study of patient tolerance in a group of Crohn's disease (CD) patients with a new fish oil derivative consisting of 500-mg capsules of eicosapentaenoic-docosahexaenoic (EPA 40%-DHA 20%), a free fatty acid mixture (Purepa), and we also evaluated its incorporation into phospholipids, both in plasma and in red cell membranes. Five groups of 10 CD patients in remission received nine Purepa capsules daily in four different preparations (A: uncoated, B: coated, pH 5.5; C: coated, pH 5.5, 60 min time release; D: coated, pH 6.9) and 12 x 1-g capsules daily of a triglyceride preparation (Max-EPA, EPA 18%-DHA 10%), respectively. We coated three of the four Purepa preparations in order to delay the release of contents in an attempt to minimize the side effects. After six weeks of treatment, the group taking Purepa capsules, coated, pH 5.5, 60 min time release (group C) showed the best incorporation of EPA and DHA in red blood cell phospholipid membranes (EPA from 0.2 to 4.4%, DHA from 3.7 to 6.3%), and no side effects were registered, whereas in all other groups side effects were experienced in 50% or more of subjects. This new preparation will make it possible to treat patients for long periods.

  15. Characterization and diagenesis of strong-acid carboxyl groups in humic substances

    USGS Publications Warehouse

    Leenheer, J.A.; Wershaw, R. L.; Brown, G.K.; Reddy, M.M.

    2003-01-01

    A small fraction of carboxylic acid functional groups in humic substances are exceptionally acidic with pKa values as low as 0.5. A review of acid-group theory eliminated most models and explanations for these exceptionally acidic carboxyl groups. These acidic carboxyl groups in Suwannee River fulvic acid were enriched by a 2-stage fractionation process and the fractions were characterized by elemental, molecular-weight, and titrimetric analyses, and by infrared and 13C- and 1H-nuclear magnetic resonance spectrometry. An average structural model of the most acidic fraction derived from the characterization data indicated a high density of carboxyl groups clustered on oxygen-heterocycle alicyclic rings. Intramolecular H-bonding between adjacent carboxyl groups in these ring structures enhanced stabilization of the carboxylate anion which results in low pKa1 values. The standard, tetrahydrofuran tetracarboxylic acid, was shown to have similar acidity characteristics to the highly acidic fulvic acid fraction. The end products of 3 known diagenetic pathways for the formation of humic substances were shown to result in carboxyl groups clustered on oxygen-heterocycle alicyclic rings.

  16. Oxidoreduction of different hydroxyl groups in bile acids during their enterohepatic circulation in man

    SciTech Connect

    Bjoerkhem, I.L.; Liljeqvist, L.; Nilsell, K.; Einarsson, K.

    1986-02-01

    The extent of oxidoreduction of the 3 alpha-, 7 alpha- and 12 alpha-hydroxyl groups in bile acids during the enterohepatic circulation in man was studied with the use of (3 beta-/sup 3/H)-labeled deoxycholic acid and cholic acid, (7 beta-/sup 3/H)-labeled cholic acid, and (12 beta-/sup 3/H)-labeled deoxycholic acid and cholic acid. Each (/sup 3/H)-labeled bile acid was given per os to healthy volunteers, together with the corresponding (24-/sup 14/C)-labeled bile acid. The rate of oxidoreduction was calculated from the decrease in the ratio between /sup 3/H and /sup 14/C in the respective bile acid isolated from duodenal contents collected at different time intervals after administration of the labeled bile acids. The mean fractional conversion rate was found to be 0.29 day-1 for the 3 alpha-hydroxyl group in deoxycholic acid (n = 2), 0.18 day-1 for the 12 alpha-hydroxyl group in deoxycholic acid (n = 6), 0.09 day-1 for the 3 alpha-hydroxyl group in cholic acid (n = 3), 0.05 day-1 for the 7 alpha-hydroxyl group in cholic acid (n = 2), and 0.03 day-1 for the 12 alpha-hydroxyl group in cholic acid (n = 2). The extent of oxidoreduction of the 12 alpha-hydroxyl group in (12 beta-/sup 3/H)-labeled deoxycholic acid given to two patients operated with subtotal colectomy and ileostomy was markedly reduced (less than 20% of normal).

  17. Splitting failure in side walls of a large-scale underground cavern group: a numerical modelling and a field study.

    PubMed

    Wang, Zhishen; Li, Yong; Zhu, Weishen; Xue, Yiguo; Yu, Song

    2016-01-01

    Vertical splitting cracks often appear in side walls of large-scale underground caverns during excavations owing to the brittle characteristics of surrounding rock mass, especially under the conditions of high in situ stress and great overburden depth. This phenomenon greatly affects the integral safety and stability of the underground caverns. In this paper, a transverse isotropic constitutive model and a splitting failure criterion are simultaneously proposed and secondly programmed in FLAC3D to numerically simulate the integral stability of the underground caverns during excavations in Dagangshan hydropower station in Sichuan province, China. Meanwhile, an in situ monitoring study on the displacement of the key points of the underground caverns has also been carried out, and the monitoring results are compared with the numerical results. From the comparative analysis, it can be concluded that the depths of splitting relaxation area obtained by numerical simulation are almost consistent with the actual in situ monitoring values, as well as the trend of the displacement curves, which shows that the transverse isotropic constitutive model combining with the splitting failure criterion is appropriate for investigating the splitting failure in side walls of large-scale underground caverns and it will be a helpful guidance of predicting the depths of splitting relaxation area in surrounding rock mass.

  18. Efficient photosensitization of terbium ions enabled by hydrolysis of siloxy groups in ligands with specific side-chains.

    PubMed

    Wang, QianMing; Ogawa, Keishiro; Li, Yan; Tamiaki, Hitoshi

    2011-01-01

    We have demonstrated the first observable case of efficient energy transfer from poly-ligands to terbium ions through cross-linked siloxane in solution. The intensification of green luminescence was easily perceived by the naked eye under UV-254 nm illumination, where even the terbium dopants reached 0.1 μM. Moreover, the nano-scale fibrous structure (diameter 100-200 nm) aggregated to a micro-meter size round plate (diameter 1.1 μm). In addition, compound 1 equipped with three long tetradecyl chains in gels gained more of an advantage over the doubly tetradecylated compounds 2 and 3 in terms of energy migration to terbium ions due to side chain effects.

  19. Insights into genetic diversity, parentage, and group composition of Atlantic white-sided dolphins (Lagenorhynchus acutus) off the west of Ireland based on nuclear and mitochondrial genetic markers.

    PubMed

    Mirimin, Luca; Banguera-Hinestroza, Eulalia; Dillane, Eileen; Hoelzel, Alan R; Cross, Tom F; Rogan, Emer

    2011-01-01

    The analysis of stranding events and the application of molecular markers can be powerful tools to study cryptic biological aspects of delphinid species that occur mainly in open ocean habitat. In the present study, we investigated nuclear and mitochondrial genetic variability of Atlantic white-sided dolphins that stranded from 1990 to 2006 (n = 42) along the west coast of Ireland, using 8 microsatellite loci and 599 bp of the mitochondrial DNA control region. Results from both classes of markers are concordant with the hypothesis of a large random-mating population of white-sided dolphins along the west coast of Ireland. In addition, the analyses of 2 live mass stranding events (19 and 5 individuals, respectively) revealed that dolphins within each group were mainly unrelated to each other, suggesting dispersal of both sexes from the natal group (i.e., no natal phylopatry). Parentage analyses allowed the identification of mother-offspring pairs but ruled out all adult males as possible fathers. In combination with data on age of individuals, these results confirmed previous knowledge on life-history parameters, with sexually mature females ranging between 11 and 15 years of age and an interbirth interval of at least 2 years. The present study provides novel information on population and group composition of Atlantic white-sided dolphins along the west coast of Ireland, where population and social structure of the species are still poorly understood.

  20. Enhancement of 5-aminolevulinic acid-based fluorescence detection of side population-defined glioma stem cells by iron chelation

    PubMed Central

    Wang, Wenqian; Tabu, Kouichi; Hagiya, Yuichiro; Sugiyama, Yuta; Kokubu, Yasuhiro; Murota, Yoshitaka; Ogura, Shun-ichiro; Taga, Tetsuya

    2017-01-01

    Cancer stem cells (CSCs) are dominantly responsible for tumor progression and chemo/radio-resistance, resulting in tumor recurrence. 5-aminolevulinic acid (ALA) is metabolized to fluorescent protoporphyrin IX (PpIX) specifically in tumor cells, and therefore clinically used as a reagent for photodynamic diagnosis (PDD) and therapy (PDT) of cancers including gliomas. However, it remains to be clarified whether this method could be effective for CSC detection. Here, using flow cytometry-based analysis, we show that side population (SP)-defined C6 glioma CSCs (GSCs) displayed much less 5-ALA-derived PpIX fluorescence than non-GSCs. Among the C6 GSCs, cells with ultralow PpIX fluorescence exhibited dramatically higher tumorigenicity when transplanted into the immune-deficient mouse brain. We further demonstrated that the low PpIX accumulation in the C6 GSCs was enhanced by deferoxamine (DFO)-mediated iron chelation, not by reserpine-mediated inhibition of PpIX-effluxing ABCG2. Finally, we found that the expression level of the gene for heme oxygenase-1 (HO-1), a heme degradation enzyme, was high in C6 GSCs, which was further up-regulated when treated with 5-ALA. Our results provide important new insights into 5-ALA-based PDD of gliomas, particularly photodetection of SP-defined GSCs by iron chelation based on their ALA-PpIX-Heme metabolism. PMID:28169355

  1. Interaction of charged amino-acid side chains with ions: an optimization strategy for classical force fields.

    PubMed

    Kahlen, Jens; Salimi, Leila; Sulpizi, Marialore; Peter, Christine; Donadio, Davide

    2014-04-10

    Many well-established classical biomolecular force fields, fitted on the solvation properties of single ions, do not necessarily describe all the details of ion pairing accurately, especially for complex polyatomic ions. Depending on the target application, it might not be sufficient to reproduce the thermodynamics of ion pairing, but it may also be necessary to correctly capture structural details, such as the coordination mode. In this work, we analyzed how classical force fields can be optimized to yield a realistic description of these different aspects of ion pairing. Given the prominent role of the interactions of negatively charged amino-acid side chains and divalent cations in many biomolecular systems, we chose calcium acetate as a benchmark system to devise a general optimization strategy that we applied to two popular force fields, namely, GROMOS and OPLS-AA. Using experimental association constants and first-principles molecular dynamics simulations as a reference, we found that small modifications of the van der Waals ion-ion interaction parameters allow a systematic improvement of the essential thermodynamic and structural properties of ion pairing.

  2. Probing the effects of the ester functional group, alkyl side chain length and anions on the bulk nanostructure of ionic liquids: a computational study.

    PubMed

    Fakhraee, Mostafa; Gholami, Mohammad Reza

    2016-04-14

    The effects of ester addition on nanostructural properties of biodegradable ILs composed of 1-alkoxycarbonyl-3-alkyl-imidazolium cations ([C1COOCnC1im](+), n = 1, 2, 4) combined with [Br](-), [NO3](-), [BF4](-), [PF6](-), [TfO](-), and [Tf2N](-) were explored by using the molecular dynamics (MD) simulations and quantum theory of atoms in molecules (QTAIM) analysis at 400 K. Various thermodynamic properties of these ILs were extensively computed in our earlier work (Ind. Eng. Chem. Res., 2015, 54, 11678-11700). Nano-scale segregation analysis demonstrates the formation of a small spherical island-like hydrocarbon within the continuous ionic domain for ILs with short alkyl side chain ([C1COOC1C1im]), and a sponge-like nanostructure for the compound with long alkyl side chain ([C1COOC4C1im]). Ester-functionalized ILs with ethyl side chain ([C1COOC2C1im]) are the turning point between two different morphologies. Non-polar channels were observed for [C1COOC4C1im] ILs composed of smaller anions such as [Br] and [NO3], whereas clustering organization was found for the other anions. Formation of the spherical micelle-like nanostructure was seen for lengthened cations. Finally, the incorporation of an ester group into the alkyl side chain of the cation leads to stronger segregation between charged and uncharged networks, which consequently increased the possibility of self-assembly and micelle formation.

  3. Enhanced phagocytosis of group A streptococci M type 6 by oleic acid

    SciTech Connect

    Speert, D.P.; Quie, P.G.; Wannamaker, L.W.

    1981-04-01

    M protein, located on the surface fimbriae of group A streptococci, is antiphagocytic by unknown means. It is known that oleic acid kills group A streptococci and distorts the fimbriae. The effect of oleic acid on phagocytosis of group A streptococci was examined. Phagocytosis of a strain possessing M protein (M+) and its M- variant was assessed by uptake of radiolabeled bacteria and by chemiluminescence. The M- but not the M+ streptococci were well phagocytized and induced chemiluminescence. Oleic acid-killed and heat-killed streptococci (both M+ and M-) were readily phagocytized and induced sustained chemiluminescence. M+ streptococci killed by ultraviolet irradiation were inefficiently phagocytized and did not induce chemiluminescence. Oleic acid-killed M+ streptococci absorbed type-specific antibody. An extract of M protein reduced the bactericidal capacity of oleic acid. It is proposed that oleic acid may bind to and alter the M protein of group A streptococci and thereby enhance phagocytosis.

  4. The methyl group as a source of structural diversity in heterocyclic chemistry: side chain functionalization of picolines and related heterocycles.

    PubMed

    Mamane, Victor; Aubert, Emmanuel; Fort, Yves

    2007-09-14

    The reaction of 2-picoline at the methyl group with NDA and KDA followed by dimethyldisulfide trapping furnished, respectively, dithioacetals and trithioortho esters with high selectivity. The method was successfully applied to other methyl-substituted pyridines, quinolines, and pyrazines. Dithioketals were prepared by a one-pot procedure involving the reaction of metalated 2-picoline with 2 equiv of dimethyldisulfide followed by in situ trapping with a second electrophile. All of the generated thio-substituted compounds were efficiently transformed in presence of mercury salts or under oxidizing conditions to other functional groups comprising aldehydes, ketones, ketals, thiol esters, orthoesters, and esters.

  5. MAPPING THE DARK SIDE WITH DEIMOS: GLOBULAR CLUSTERS, X-RAY GAS, AND DARK MATTER IN THE NGC 1407 GROUP

    SciTech Connect

    Romanowsky, Aaron J.; Strader, Jay; Brodie, Jean P.; Johnson, Ria; Ponman, Trevor

    2009-06-15

    NGC 1407 is the central elliptical in a nearby evolved group of galaxies apparently destined to become a galaxy cluster core. We use the kinematics of globular clusters (GCs) to probe the dynamics and mass profile of the group's center, out to a radius of 60 kpc ({approx}10 galaxy effective radii)-the most extended data set to date around an early-type galaxy. This sample consists of 172 GC line-of-sight velocities, most of them newly obtained using Keck/DEIMOS, with a few additional objects identified as dwarf-globular transition objects or as intragroup GCs. We find weak rotation for the outer parts of the GC system (v/{sigma} {approx} 0.2), with a rotational misalignment between the metal-poor and metal-rich GCs. The velocity dispersion profile declines rapidly to a radius of {approx}20 kpc, and then becomes flat or rising to {approx}60 kpc. There is evidence that the GC orbits have a tangential bias that is strongest for the metal-poor GCs-in possible contradiction to theoretical expectations. We construct cosmologically motivated galaxy+dark halo dynamical models and infer a total mass within 60 kpc of {approx}3 x 10{sup 12} M {sub sun}, which extrapolates to a virial mass of {approx}6 x 10{sup 13} M {sub sun} for a typical lambda cold dark matter ({lambda}CDM) halo-in agreement with results from kinematics of the group galaxies. We present an independent Chandra-based analysis, whose relatively high mass at {approx}20 kpc disagrees strongly with the GC-based result unless the GCs are assumed to have a peculiar orbit distribution, and we therefore discuss more generally some comparisons between X-ray and optical results. The group's B-band mass-to-light ratio of {approx}800 (uncertain by a factor of {approx}2) in Solar units is extreme even for a rich galaxy cluster, much less a poor group-placing it among the most dark matter (DM) dominated systems in the universe, and also suggesting a massive reservoir of baryons lurking in an unseen phase, in addition to

  6. Inversion of the stereochemistry around the sulfur atom of the axial methionine side chain through alteration of amino acid side chain packing in Hydrogenobacter thermophilus cytochrome C552 and its functional consequences.

    PubMed

    Tai, Hulin; Tonegawa, Ken; Shibata, Tomokazu; Hemmi, Hikaru; Kobayashi, Nagao; Yamamoto, Yasuhiko

    2013-07-16

    In cytochrome c, the coordination of the axial Met Sδ atom to the heme Fe atom occurs in one of two distinctly different stereochemical manners, i.e., R and S configurations, depending upon which of the two lone pairs of the Sδ atom is involved in the bond; hence, the Fe-coordinated Sδ atom becomes a chiral center. In this study, we demonstrated that an alteration of amino acid side chain packing induced by the mutation of a single amino acid residue, i.e., the A73V mutation, in Hydrogenobacter thermophilus cytochrome c552 (HT) forces the inversion of the stereochemistry around the Sδ atom from the R configuration [Travaglini-Allocatelli, C., et al. (2005) J. Biol. Chem. 280, 25729-25734] to the S configuration. Functional comparison between the wild-type HT and the A73V mutant possessing the R and S configurations as to the stereochemistry around the Sδ atom, respectively, demonstrated that the redox potential (Em) of the mutant at pH 6.00 and 25 °C exhibited a positive shift of ∼20 mV relative to that of the wild-type HT, i.e., 245 mV, in an entropic manner. Because these two proteins have similar enthalpically stabilizing interactions, the difference in the entropic contribution to the Em value between them is likely to be due to the effect of the conformational alteration of the axial Met side chain associated with the inversion of the stereochemistry around the Sδ atom due to the effect of mutation on the internal mobility of the loop bearing the axial Met. Thus, the present study demonstrated that the internal mobility of the loop bearing the axial Met, relevant to entropic control of the redox function of the protein, is affected quite sensitively by the contextual stereochemical packing of amino acid side chains in the proximity of the axial Met.

  7. Identification of Oxygenated Fatty Acid as a Side Chain of Lipo-Alkaloids in Aconitum carmichaelii by UHPLC-Q-TOF-MS and a Database.

    PubMed

    Liang, Ying; Wu, Jian-Lin; Leung, Elaine Lai-Han; Zhou, Hua; Liu, Zhongqiu; Yan, Guanyu; Liu, Ying; Liu, Liang; Li, Na

    2016-03-31

    Lipo-alkaloid is a kind of C19-norditerpenoid alkaloid usually found in Aconitum species. Structurally, they contain an aconitane skeleton and one or two fatty acid moieties of 3-25 carbon chains with 1-6 unsaturated degrees. Analysis of the lipo-alkaloids in roots of Aconitum carmichaelii resulted in the isolation of six known pure lipo-alkaloids (A1-A6) and a lipo-alkaloid mixture (A7). The mixture shared the same aconitane skeleton of 14-benzoylmesaconine, but their side chains were determined to be 9-hydroxy-octadecadienoic acid, 13-hydroxy-octadecadienoic acid and 10-hydroxy-octadecadienoic acid, respectively, by MS/MS analysis after alkaline hydrolysis. To our knowledge, this is the first time of the reporting of the oxygenated fatty acids as the side chains in naturally-occurring lipo-alkaloids. In order to identify more lipo-alkaloids, a compound database was established based on various combinations between the aconitane skeleton and the fatty acid chain, and then, the identification of lipo-alkaloids was conducted using the database, UHPLC-Q-TOF-MS and MS/MS. Finally, 148 lipo-alkaloids were identified from A. carmichaelii after intensive MS/MS analysis, including 93 potential new compounds and 38 compounds with oxygenated fatty acid moieties.

  8. Fluorescent macrocyclic probes with pendant functional groups as markers of acidic organelles within live cells.

    PubMed

    Wadhavane, Prashant D; Izquierdo, M Ángeles; Lutters, Dennis; Burguete, M Isabel; Marín, María J; Russell, David A; Galindo, Francisco; Luis, Santiago V

    2014-02-07

    A new family of acidity sensitive fluorescent macrocycles has been synthesized and fully characterized. Their photophysical properties including emission quantum yield and fluorescence lifetime have been determined. The acid-base properties of the new molecules can be tuned by the incorporation of pendant functional groups. The nature of such functional groups (carboxylic acid or ester) influences dramatically the pKa of the probes, two compounds of which exhibit low values. Preliminary intracellular studies using confocal microscopy together with emission spectra of the probes from the cellular environment have shown that the synthesized fluorescent macrocycles mark the acidic organelles of RAW 264.7 macrophage cells.

  9. Modulating the self-assembly of rigid "clicked" dendrimers at the solid-liquid interface by tuning non-covalent interactions between side groups.

    PubMed

    Cadeddu, Andrea; Ciesielski, Artur; El Malah, Tamer; Hecht, Stefan; Samorì, Paolo

    2011-10-14

    First generation poly(triazole-phenylene) dendrimers equipped with peripheral alkyl or carboxylic acid groups to engage in van der Waals and hydrogen-bonding interactions, respectively, assemble into distinct two-dimensional nano-structures at the solid-liquid interface as revealed by high resolution STM investigations.

  10. Polylactide block copolymers using trimethylene carbonate with methoxyethoxy side groups for dual modification of hydrophilicity and biodegradability.

    PubMed

    Ajiro, Hiroharu; Takahashi, Yoshikazu; Akashi, Mitsuru; Fujiwara, Tomoko

    2012-10-01

    Novel block copolymers using the monomers 5-(2-methoxyethyoxymethyl)-5-methyl-[1,3]-dioxa-2-one (TMCM-MOE1OM) as a hydrophilic segment and lactides as a hydrophobic segment were designed in order to prepare controllable degradation polymers by dynamic polymer rearrangement based on the hydrophilicity. When the copolymer film contacted water, the hydrophobic polylactide (PLA) segments tend to be buried under the TMCM-MOE1OM segments due to the hydrophilicity of the methoxyethoxy groups. The copolymers were hardly degraded by both proteinase K and lipase, while both of their homopolymers, poly(trimethylene carbonate) and PLA, were degraded, which suggests that the rearrangement of the TMCM-MOE1OM segments at the outermost surface significantly improved the degradation ratio.

  11. Electroactive self-doped poly(amic acid) with oligoaniline and sulfonic acid groups: synthesis and electrochemical properties.

    PubMed

    Chi, Maoqiang; Wang, Shutao; Liang, Yuan; Chao, Danming; Wang, Ce

    2014-06-01

    A novel poly(amic acid) with pendant aniline tetramer and sulfonic acid groups (ESPAA) was synthesized by ternary polymerization and characterized by Fourier-transform infrared spectra, ((1))H NMR and gel permeation chromatography. The polymer showed good thermal stability and excellent solubility in the common organic solvents. The electrochemical properties were investigated carefully on a CHI 660A Electrochemical Workstation. The polymer displayed good electroactivity in acid, neutral and even in alkaline solutions (pH=1-10) due to the self-doping effect between aniline tetramer and sulfonic/carboxylic acid groups. It also exhibited satisfactory electrochromic performance with high contrast value, acceptable coloration efficiency and fast switching time in the range of pH=1-9.

  12. Parameterization of the Hamiltonian Dielectric Solvent (HADES) Reaction-Field Method for the Solvation Free Energies of Amino Acid Side-Chain Analogs.

    PubMed

    Zachmann, Martin; Mathias, Gerald; Antes, Iris

    2015-06-08

    Optimization of the Hamiltonian dielectric solvent (HADES) method for biomolecular simulations in a dielectric continuum is presented with the goal of calculating accurate absolute solvation free energies while retaining the model's accuracy in predicting conformational free-energy differences. The solvation free energies of neutral and polar amino acid side-chain analogs calculated by using HADES, which may optionally include nonpolar contributions, were optimized against experimental data to reach a chemical accuracy of about 0.5 kcal mol(-1). The new parameters were evaluated for charged side-chain analogs. The HADES results were compared with explicit-solvent, generalized Born, Poisson-Boltzmann, and QM-based methods. The potentials of mean force (PMFs) between pairs of side-chain analogs obtained by using HADES and explicit-solvent simulations were used to evaluate the effects of the improved parameters optimized for solvation free energies on intermolecular potentials.

  13. Using amino acids for the chromatofocusing of metal ions on silica with bonded tetraethylenepentamine groups

    NASA Astrophysics Data System (ADS)

    Ivanov, A. V.

    2014-09-01

    Amino acid-based eluents are used for the chromatofocusing of metal ions on Tetren-SiO2 chelating sorbent (silica with bonded tetraethylenepentamine groups) for the first time. The smoothest quasilinear pH gradients form for eluents based on glutamic and aspartic acids. The separation of Mn2+, Cr3+, Co2+, Ni2+, and Cu2+ is achieved.

  14. Mouse Siglec-1 Mediates trans-Infection of Surface-bound Murine Leukemia Virus in a Sialic Acid N-Acyl Side Chain-dependent Manner.

    PubMed

    Erikson, Elina; Wratil, Paul R; Frank, Martin; Ambiel, Ina; Pahnke, Katharina; Pino, Maria; Azadi, Parastoo; Izquierdo-Useros, Nuria; Martinez-Picado, Javier; Meier, Chris; Schnaar, Ronald L; Crocker, Paul R; Reutter, Werner; Keppler, Oliver T

    2015-11-06

    Siglec-1 (sialoadhesin, CD169) is a surface receptor on human cells that mediates trans-enhancement of HIV-1 infection through recognition of sialic acid moieties in virus membrane gangliosides. Here, we demonstrate that mouse Siglec-1, expressed on the surface of primary macrophages in an interferon-α-responsive manner, captures murine leukemia virus (MLV) particles and mediates their transfer to proliferating lymphocytes. The MLV infection of primary B-cells was markedly more efficient than that of primary T-cells. The major structural protein of MLV particles, Gag, frequently co-localized with Siglec-1, and trans-infection, primarily of surface-bound MLV particles, efficiently occurred. To explore the role of sialic acid for MLV trans-infection at a submolecular level, we analyzed the potential of six sialic acid precursor analogs to modulate the sialylated ganglioside-dependent interaction of MLV particles with Siglec-1. Biosynthetically engineered sialic acids were detected in both the glycolipid and glycoprotein fractions of MLV producer cells. MLV released from cells carrying N-acyl-modified sialic acids displayed strikingly different capacities for Siglec-1-mediated capture and trans-infection; N-butanoyl, N-isobutanoyl, N-glycolyl, or N-pentanoyl side chain modifications resulted in up to 92 and 80% reduction of virus particle capture and trans-infection, respectively, whereas N-propanoyl or N-cyclopropylcarbamyl side chains had no effect. In agreement with these functional analyses, molecular modeling indicated reduced binding affinities for non-functional N-acyl modifications. Thus, Siglec-1 is a key receptor for macrophage/lymphocyte trans-infection of surface-bound virions, and the N-acyl side chain of sialic acid is a critical determinant for the Siglec-1/MLV interaction.

  15. Mouse Siglec-1 Mediates trans-Infection of Surface-bound Murine Leukemia Virus in a Sialic Acid N-Acyl Side Chain-dependent Manner*

    PubMed Central

    Erikson, Elina; Wratil, Paul R.; Frank, Martin; Ambiel, Ina; Pahnke, Katharina; Pino, Maria; Azadi, Parastoo; Izquierdo-Useros, Nuria; Martinez-Picado, Javier; Meier, Chris; Schnaar, Ronald L.; Crocker, Paul R.; Reutter, Werner; Keppler, Oliver T.

    2015-01-01

    Siglec-1 (sialoadhesin, CD169) is a surface receptor on human cells that mediates trans-enhancement of HIV-1 infection through recognition of sialic acid moieties in virus membrane gangliosides. Here, we demonstrate that mouse Siglec-1, expressed on the surface of primary macrophages in an interferon-α-responsive manner, captures murine leukemia virus (MLV) particles and mediates their transfer to proliferating lymphocytes. The MLV infection of primary B-cells was markedly more efficient than that of primary T-cells. The major structural protein of MLV particles, Gag, frequently co-localized with Siglec-1, and trans-infection, primarily of surface-bound MLV particles, efficiently occurred. To explore the role of sialic acid for MLV trans-infection at a submolecular level, we analyzed the potential of six sialic acid precursor analogs to modulate the sialylated ganglioside-dependent interaction of MLV particles with Siglec-1. Biosynthetically engineered sialic acids were detected in both the glycolipid and glycoprotein fractions of MLV producer cells. MLV released from cells carrying N-acyl-modified sialic acids displayed strikingly different capacities for Siglec-1-mediated capture and trans-infection; N-butanoyl, N-isobutanoyl, N-glycolyl, or N-pentanoyl side chain modifications resulted in up to 92 and 80% reduction of virus particle capture and trans-infection, respectively, whereas N-propanoyl or N-cyclopropylcarbamyl side chains had no effect. In agreement with these functional analyses, molecular modeling indicated reduced binding affinities for non-functional N-acyl modifications. Thus, Siglec-1 is a key receptor for macrophage/lymphocyte trans-infection of surface-bound virions, and the N-acyl side chain of sialic acid is a critical determinant for the Siglec-1/MLV interaction. PMID:26370074

  16. Role of Side Chains in β-Sheet Self-Assembly into Peptide Fibrils. IR and VCD Spectroscopic Studies of Glutamic Acid-Containing Peptides.

    PubMed

    Tobias, Fernando; Keiderling, Timothy A

    2016-05-10

    Poly(glutamic acid) at low pH self-assembles after incubation at higher temperature into fibrils composed of antiparallel sheets that are stacked in a β2-type structure whose amide carbonyls have bifurcated H-bonds involving the side chains from the next sheet. Oligomers of Glu can also form such structures, and isotope labeling has provided insight into their out-of-register antiparallel structure [ Biomacromolecules 2013 , 14 , 3880 - 3891 ]. In this paper we report IR and VCD spectra and transmission electron micrograph (TEM) images for a series of alternately sequenced oligomers, Lys-(Aaa-Glu)5-Lys-NH2, where Aaa was varied over a variety of polar, aliphatic, or aromatic residues. Their spectral and TEM data show that these oligopeptides self-assemble into different structures, both local and morphological, that are dependent on both the nature of the Aaa side chains and growth conditions employed. Such alternate peptides substituted with small or polar residues, Ala and Thr, do not yield fibrils; but with β-branched aliphatic residues, Val and Ile, that could potentially pack with Glu side chains, these oligopeptides do show evidence of β2-stacking. By contrast, for Leu, with longer side chains, only β1-stacking is seen while with even larger Phe side chains, either β-form can be detected separately, depending on preparation conditions. These structures are dependent on high temperature incubation after reducing the pH and in some cases after sonication of initial fibril forms and reincubation. Some of these fibrillar peptides, but not all, show enhanced VCD, which can offer evidence for formation of long, multistrand, often twisted structures. Substitution of Glu with residues having selected side chains yields a variety of morphologies, leading to both β1- and β2-structures, that overall suggests two different packing modes for the hydrophobic side chains depending on size and type.

  17. Adherence of group B streptococci to adult and neonatal epithelial cells mediated by lipoteichoic acid.

    PubMed Central

    Teti, G; Tomasello, F; Chiofalo, M S; Orefici, G; Mastroeni, P

    1987-01-01

    We have investigated the role of lipoteichoic acid in mediating the adherence of different serotypes of group B streptococci to human adult and neonatal epithelial cells. Pretreatment of neonatal buccal and vaginal epithelial cells with lipoteichoic acid, but not with deacylated lipoteichoic acid, induced a marked inhibition in the adherence of all strains tested. Pretreatment of bacteria with substances known to bind lipoteichoic acid, such as monoclonal and polyclonal antipolyglycerophosphate antibodies and albumin, also resulted in adherence inhibition. Group B streptococci adhered in 6- to 10-fold-higher numbers to buccal epithelial cells from neonates older than 3 days than to those from neonates less than 1 day old. This increase in receptiveness for group B streptococci was paralleled by an increased ability of epithelial cells from older neonates to bind group B streptococcal lipoteichoic acid. These data suggest a role for the lipid portion of lipoteichoic acid in the adherence of different serotypes of group B streptococci to vaginal and neonatal epithelial cells. PMID:3316030

  18. Reduction of the 20-Carbonyl Group of C-21 Steroids by Spores of Fusarium solani and Other Microorganisms. I. Side-Chain Degradation, Epoxide Cleavage, and Substrate Specificity

    PubMed Central

    Plourde, Rosaire; El-Tayeb, Ossama M.; Hafez-Zedan, Hamdallah

    1972-01-01

    The spores of Fusarium solani reduced the C2-carbonyl group, 1-dehydrogenated ring „A” and cleaved the side chain of 16α, 17α-oxidopregn-4-ene-3, 20-dione (16α, 17α-oxidoprogesterone)(I) to give the following products: 20α-hydroxy-16α, 17α-oxidopregn-4-en-3-one(II); 20α-hydroxy-16α, 17α-oxidopregna-1, 4-dien-3-one(III); 16α-hydroxy-17a-oxa-androsta-1, 4-diene-3, 17-dione (16α-hydroxy-1-dehydrotestololactone)(IV); and 16α, 17β-dihydroxy-androsta-1, 4-dien-3-one (16α-hydroxy-1-dehydrotestosterone)(V). When II was used as a substrate, it was metabolized into III, IV, and V at a slower rate than I. Furthermore, 16α-hydroxy-androst-4-ene-3, 17-dione (16α-hydroxyandrostenedione)(X) was transformed into IV and V. Pregn-4-ene-3, 20-dione (progesterone)(XII) was transformed into androsta-1, 4-diene-3, 17-dione (androstadienedione)(VIII) and 17a-oxa-androsta-1, 4-diene-3, 17-dione (1-dehydrotestololactone)(IX), while 17α-hydroxy-pregn-4-ene-3, 20-dione (17α-hydroxyprogesterone)(VI) was converted into its 1-dehydro analogue (VII) without accumulation of any 20-dihydro compounds. Substrate specificity in the 20-reductase system of F. solani, Cylindrocarpon radicicola, Septomyxa affinis, Bacillus lentus, and three strains of B. sphaericus are demonstrated. The 20-reductase is active only on steroids having the 16α, 17α-oxido, and Δ4-3-keto functions. Evidence of competition between side-chain degrading enzymes and the 20-reductase for the steroid molecule and evidence of side-chain degradation followed by epoxide cleavage (and not the reverse) are presented. A mechanism for the epoxide opening by nongerminating spores of F. solani is postulated. PMID:5021973

  19. Synthesis, characterization and catalytic activity of acid-base bifunctional materials through protection of amino groups

    SciTech Connect

    Shao, Yanqiu; Liu, Heng; Yu, Xiaofang; Guan, Jingqi; Kan, Qiubin

    2012-03-15

    Graphical abstract: Acid-base bifunctional mesoporous material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized under low acidic medium through protection of amino groups. Highlights: Black-Right-Pointing-Pointer The acid-base bifunctional material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized through protection of amino groups. Black-Right-Pointing-Pointer The obtained bifunctional material was tested for aldol condensation. Black-Right-Pointing-Pointer The SO{sub 3}H-SBA-15-NH{sub 2} catalyst containing amine and sulfonic acid groups exhibited excellent acid-basic properties. -- Abstract: Acid-base bifunctional mesoporous material SO{sub 3}H-SBA-15-NH{sub 2} was successfully synthesized under low acidic medium through protection of amino groups. X-ray diffraction (XRD), N{sub 2} adsorption-desorption, transmission electron micrographs (TEM), back titration, {sup 13}C magic-angle spinning (MAS) NMR and {sup 29}Si magic-angle spinning (MAS) NMR were employed to characterize the synthesized materials. The obtained bifunctional material was tested for aldol condensation reaction between acetone and 4-nitrobenzaldehyde. Compared with monofunctional catalysts of SO{sub 3}H-SBA-15 and SBA-15-NH{sub 2}, the bifunctional sample of SO{sub 3}H-SBA-15-NH{sub 2} containing amine and sulfonic acid groups exhibited excellent acid-basic properties, which make it possess high activity for the aldol condensation.

  20. Solving nucleic acid structures by molecular replacement: examples from group II intron studies

    SciTech Connect

    Marcia, Marco Humphris-Narayanan, Elisabeth; Keating, Kevin S.; Somarowthu, Srinivas; Rajashankar, Kanagalaghatta; Pyle, Anna Marie

    2013-11-01

    Strategies for phasing nucleic acid structures by molecular replacement, using both experimental and de novo designed models, are discussed. Structured RNA molecules are key players in ensuring cellular viability. It is now emerging that, like proteins, the functions of many nucleic acids are dictated by their tertiary folds. At the same time, the number of known crystal structures of nucleic acids is also increasing rapidly. In this context, molecular replacement will become an increasingly useful technique for phasing nucleic acid crystallographic data in the near future. Here, strategies to select, create and refine molecular-replacement search models for nucleic acids are discussed. Using examples taken primarily from research on group II introns, it is shown that nucleic acids are amenable to different and potentially more flexible and sophisticated molecular-replacement searches than proteins. These observations specifically aim to encourage future crystallographic studies on the newly discovered repertoire of noncoding transcripts.

  1. Characterizing hydrophobicity of amino acid side chains in a protein environment via measuring contact angle of a water nanodroplet on planar peptide network.

    PubMed

    Zhu, Chongqin; Gao, Yurui; Li, Hui; Meng, Sheng; Li, Lei; Francisco, Joseph S; Zeng, Xiao Cheng

    2016-11-15

    Hydrophobicity of macroscopic planar surface is conventionally characterized by the contact angle of water droplets. However, this engineering measurement cannot be directly extended to surfaces of proteins, due to the nanometer scale of amino acids and inherent nonplanar structures. To measure the hydrophobicity of side chains of proteins quantitatively, numerous parameters were developed to characterize behavior of hydrophobic solvation. However, consistency among these parameters is not always apparent. Herein, we demonstrate an alternative way of characterizing hydrophobicity of amino acid side chains in a protein environment by constructing a monolayer of amino acids (i.e., artificial planar peptide network) according to the primary and the β-sheet secondary structures of protein so that the conventional engineering measurement of the contact angle of a water droplet can be brought to bear. Using molecular dynamics simulations, contact angles θ of a water nanodroplet on the planar peptide network, together with excess chemical potentials of purely repulsive methane-sized Weeks-Chandler-Andersen solute, are computed. All of the 20 types of amino acids and the corresponding planar peptide networks are studied. Expectedly, all of the planar peptide networks with nonpolar amino acids are hydrophobic due to θ [Formula: see text] 90°, whereas all of the planar peptide networks of the polar and charged amino acids are hydrophilic due to θ [Formula: see text] 90°. Planar peptide networks of the charged amino acids exhibit complete-wetting behavior due to θ [Formula: see text] 0°. This computational approach for characterization of hydrophobicity can be extended to artificial planar networks of other soft matter.

  2. Hydrogen-bond acidic functionalized carbon nanotubes (CNTs) with covalently-bound hexafluoroisopropanol groups

    SciTech Connect

    Fifield, Leonard S.; Grate, Jay W.

    2010-06-01

    Fluorinated hydrogen-bond acidic groups are directly attached to the backbone of single walled carbon nanotubes (SWCNTs) without the introduction of intermediate electron donating surface groups. Hexafluoroalcohol functional groups are exceptionally strong hydrogen bond acids, and are added to the nanotube surface using the aryl diazonium approach to create hydrogen-bond acidic carbon nanotube (CNT) surfaces. These groups can promote strong hydrogen-bonding interactions with matrix materials in composites or with molecular species to be concentrated and sensed. In the latter case, this newly developed material is expected to find useful application in chemical sensors and in CNT-based preconcentrator devices for the detection of pesticides, chemical warfare agents and explosives.

  3. Thermal And Spectroscopic Analyses Of Next Generation Caustic Side Solvent Extraction Solvent Contacted With 3, 8, And 16 Molar Nitric Acid

    SciTech Connect

    Fondeur, F. F.; Fink, S. D.

    2011-12-07

    A new solvent system referred to as Next Generation Solvent or NGS, has been developed at Oak Ridge National Laboratory for the removal of cesium from alkaline solutions in the Caustic Side Solvent Extraction process. The NGS is proposed for deployment at MCU{sup a} and at the Salt Waste Processing Facility. This work investigated the chemical compatibility between NGS and 16 M, 8 M, and 3 M nitric acid from contact that may occur in handling of analytical samples from MCU or, for 3 M acid, which may occur during contactor cleaning operations at MCU. This work shows that reactions occurred between NGS components and the high molarity nitric acid. Reaction rates are much faster in 8 M and 16 M nitric acid than in 3 M nitric acid. In the case of 16 M and 8 M nitric acid, the nitric acid reacts with the extractant to produce initially organo-nitrate species. The reaction also releases soluble fluorinated alcohols such as tetrafluoropropanol. With longer contact time, the modifier reacts to produce a tarry substance with evolved gases (NO{sub x} and possibly CO). Calorimetric analysis of the reaction product mixtures revealed that the organo-nitrates reaction products are not explosive and will not deflagrate.

  4. Discovery of 2-azetidinone and 1H-pyrrole-2,5-dione derivatives containing sulfonamide group at the side chain as potential cholesterol absorption inhibitors.

    PubMed

    Yuan, Xinrui; Lu, Peng; Xue, Xiaojian; Qin, Hui; Fan, Chen; Wang, Yubin; Zhang, Qi

    2016-02-01

    Cholesterol absorption inhibitor (CAI) targeting Niemann-Pick C1-like1 protein was developed for the treatment of hyperlipidaemia and only ezetimibe was approved so far. For developing novel CAIs, we synthesized sixteen 2-azetidinone derivatives and thirteen 1H-pyrrole-2,5-dione derivatives containing sulfonamide group at the side chain, and their inhibitory activity of cholesterol absorption was evaluated in Caco-2 cell line in vitro. Furthermore, top six compounds were measured by cytotoxicity and partition coefficient, and 2-azetidinone analogue 9e was selected for in vivo study. Finally, 9e considerably reduced total cholesterol, LDL-C, FFA and triglyceride in the serum and increased the rate of HDL-C to total cholesterol, suggesting it could regulate the lipid metabolism and act as a potent CAI.

  5. Alcohol- and water-soluble bis(tpy)quaterthiophenes with phosphonium side groups: new conjugated units for metallo-supramolecular polymers.

    PubMed

    Štenclová, P; Šichová, K; Šloufová, I; Zedník, J; Vohlídal, J; Svoboda, J

    2016-01-21

    Bis(tpy)quaterthiophenes with symmetrically distributed two and four 6-bromohexyl side groups were prepared and modified by the reaction with triethylphosphine to give the corresponding ionic species. Both ionic and non-ionic bis(tpy)quaterthiophenes (unimers) were assembled with Zn(2+) and Fe(2+) ions to conjugated metallo-supramolecular polymers (MSPs), of which the ionic ones are soluble in alcohols and those derived from tetrasubstituted unimers are soluble even in water. The differences in assembly are specified between systems with (i) ionic and non-ionic unimers, (ii) Zn(2+) and Fe(2+) ion couplers, and (iii) methanol and water solvents. A substantial decrease in the stability of Fe-MSPs and a surprisingly high red shift of the luminescence band of Zn-MSPs were observed on going from methanol to aqueous solutions.

  6. The role of water and K + ion in the charge transfer between PO4- groups of DNA and the lysine + and arginine + side chains of histone proteins

    NASA Astrophysics Data System (ADS)

    Bende, A.; Bogár, F.; Ladik, J.

    2008-09-01

    We have calculated the charge transfer (CT) between the PO4- group of DNA and the lysine (Lys) and arginine (Arg) positive side chains of histones in presence of water and K + ions. The calculations were performed at the HF + MP2 level, using the TZVP basis set. The calculations were corrected for basis set superposition error and besides Mulliken's population analysis we have introduced the - for charged systems more reliable - natural population analysis. The results show that the bare PO4--Lys and the PO4--Arg interactions become weaker, mainly, due to the presence of the K + ion. We have found 0.067 e CT for Lys and 0.050 e for Arg.

  7. Simple physics-based analytical formulas for the potentials of mean force for the interaction of amino acid side chains in water. 3. Calculation and parameterization of the potentials of mean force of pairs of identical hydrophobic side chains.

    PubMed

    Makowski, Mariusz; Sobolewski, Emil; Czaplewski, Cezary; Liwo, Adam; Ołdziej, Stanisław; No, Joo Hwan; Scheraga, Harold A

    2007-03-22

    The potentials of mean force of homodimers of the molecules modeling hydrophobic amino acid side chains (ethane (for alanine), propane (for proline), isobutane (for valine), isopentane (for leucine and isoleucine), ethylbenzene (for phenylalanine), and methyl propyl sulfide (for methionine)) were determined by umbrella-sampling molecular dynamics simulations in explicit water as functions of distance and orientation. Analytical expressions consisting of the Gay-Berne term to represent effective van der Waals interactions and the cavity term derived in paper 1 of this series were fitted to the potentials of mean force. The positions and depths of the contact minima and the positions and heights of the desolvation maxima, including their dependence on the orientation of the molecules, were well represented by the analytical expressions for all systems, which justifies use of such potentials in coarse-grain protein-folding simulations.

  8. The Synthesis of a Dipeptide from its Component Amino Acids: Protecting Groups in the Elementary Organic Laboratory.

    ERIC Educational Resources Information Center

    Young, Paul E.; Campbell, Andrew

    1982-01-01

    A simple, three-step procedure for synthesizing a dipeptide from its component amino acids is described. The dipeptide synthesized uses inexpensive amino acids having hydrocarbon side-chains and can be observed in E/Z forms by nuclear magnetic resonance spectroscopy. Each step in the synthesis produces white crystalline products using standard…

  9. Biochemical engineering of the N-acyl side chain of sialic acids alters the kinetics of a glycosylated potassium channel Kv3.1.

    PubMed

    Hall, M Kristen; Reutter, Werner; Lindhorst, Thisbe; Schwalbe, Ruth A

    2011-10-20

    The sialic acid of complex N-glycans can be biochemically engineered by substituting the physiological precursor N-acetylmannosamine with non-natural N-acylmannosamines. The Kv3.1 glycoprotein, a neuronal voltage-gated potassium channel, contains sialic acid. Western blots of the Kv3.1 glycoprotein isolated from transfected B35 neuroblastoma cells incubated with N-acylmannosamines verified sialylated N-glycans attached to the Kv3.1 glycoprotein. Outward ionic currents of Kv3.1 transfected B35 cells treated with N-pentanoylmannosamine or N-propanoylmannosamine had slower activation and inactivation rates than those of untreated cells. Therefore, the N-acyl side chain of sialic acid is intimately connected with the activation and inactivation rates of this glycosylated potassium channel.

  10. Calculation of the water-cyclohexane transfer free energies of neutral amino acid side-chain analogs using the OPLS all-atom force field.

    PubMed

    MacCallum, Justin L; Tieleman, D Peter

    2003-11-30

    We calculated the free energy of solvation of the neutral analogs of 18 amino acid side-chains (not including glycine and proline) using the OPLS all-atom force field in TIP4P water, SPC water, and cyclohexane by molecular dynamics simulation and thermodynamic integration. The average unsigned errors in the free energies of solvation in TIP4P, SPC, and cyclohexane are 4.4, 4.9, and 2.1 kJ/mol respectively. Most of the calculated hydration free energies are not favorable enough compared to experiment. The largest errors are found for tryptophan, histidine, glutamic acid, and glutamine. The average unsigned errors in the free energy of transfer from TIP4P to cyclohexane and from SPC to cyclohexane are 4.0 and 4.1 kJ/mol, respectively. The largest errors, of more than 7.5 kJ/mol, are found for histidine, glutamine, and glutamatic acid.

  11. Facile fabrication of siloxane @ poly (methylacrylic acid) core-shell microparticles with different functional groups

    NASA Astrophysics Data System (ADS)

    Zhao, Zheng-Bai; Tai, Li; Zhang, Da-Ming; Jiang, Yong

    2017-02-01

    Siloxane @ poly (methylacrylic acid) core-shell microparticles with functional groups were prepared by a facile hydrolysis-condensation method in this work. Three different silane coupling agents 3-methacryloxypropyltrimethoxysilane (MPS), 3-triethoxysilylpropylamine (APTES), and 3-glycidoxypropyltrimethoxysilane (GPTMS) were added along with tetraethoxysilane (TEOS) into the polymethylacrylic acid (PMAA) microparticle ethanol dispersion to form the Si@PMAA core-shell microparticles with different functional groups. The core-shell structure and the surface special functional groups of the resulting microparticles were measured by transmission electron microscopy and FTIR. The sizes of these core-shell microparticles were about 350-400 nm. The corresponding preparation conditions and mechanism were discussed in detail. This hydrolysis-condensation method also could be used to functionalize other microparticles which contain active groups on the surface. Meanwhile, the Si@PMAA core-shell microparticles with carbon-carbon double bonds and amino groups have further been applied to prepare hydrophobic coatings.

  12. Solving nucleic acid structures by molecular replacement: examples from group II intron studies

    PubMed Central

    Marcia, Marco; Humphris-Narayanan, Elisabeth; Keating, Kevin S.; Somarowthu, Srinivas; Rajashankar, Kanagalaghatta; Pyle, Anna Marie

    2013-01-01

    Structured RNA molecules are key players in ensuring cellular viability. It is now emerging that, like proteins, the functions of many nucleic acids are dictated by their tertiary folds. At the same time, the number of known crystal structures of nucleic acids is also increasing rapidly. In this context, molecular replacement will become an increasingly useful technique for phasing nucleic acid crystallographic data in the near future. Here, strategies to select, create and refine molecular-replacement search models for nucleic acids are discussed. Using examples taken primarily from research on group II introns, it is shown that nucleic acids are amenable to different and potentially more flexible and sophisticated molecular-replacement searches than proteins. These observations specifically aim to encourage future crystallographic studies on the newly discovered repertoire of noncoding transcripts. PMID:24189228

  13. The 4-pyridylmethyl ester as a protecting group for glutamic and aspartic acids: 'flipping' peptide charge states for characterization by positive ion mode ESI-MS.

    PubMed

    Garapati, Sriramya; Burns, Colin S

    2014-03-01

    Use of the 4-pyridylmethyl ester group for side-chain protection of glutamic acid residues in solid-phase peptide synthesis enables switching of the charge state of a peptide from negative to positive, thus making detection by positive ion mode ESI-MS possible. The pyridylmethyl ester moiety is readily removed from peptides in high yield by hydrogenation. Combining the 4-pyridylmethyl ester protecting group with benzyl ester protection reduces the number of the former needed to produce a net positive charge and allows for purification by RP HPLC. This protecting group is useful in the synthesis of highly acidic peptide sequences, which are often beset by problems with purification by standard RP HPLC and characterization by ESI-MS.

  14. Diagrammatic restored section of the Inyan Kara group, Morrison formation, and Unkpapa sandstone of the western side of the Black Hills, Wyoming and South Dakota

    USGS Publications Warehouse

    Mapel, W.J.; Gott, G.B.

    1959-01-01

    The Inyan Kara group of Early Creaceous age and the underlying Morrison formation and Unkapa sandstone of Late Jurassic age comprise about 300 to 850 feet of gently dipping predominantly nonmarine rocks that crop out along the flanks of the Black Hills in northeastern Wyoming and western South Dakota. Terailed mapping and stratigraphic studies of these rocks were made from 1952 to 1957 by the U.S. Geological Survey on behalf of the Division of Raw Materials of the U.S. Atomic Energy Commission. One of the results of the studies is a correlation of formational and informational units along the western side of the Black Hills for a distance of about 140 miles. The generalized section above, which has a greatly exaggerated vertical scale, shoes the main lithologic units that have been traced and correlated, and  the stratigraphic position of uranium deposits in various parts of the Black Hills in relation to these units. Geologists who have this sheet and the areas for which each is responsible are shown on the accompanying map. The brief text below summarizes some of the broad stratigraphic relations within the Inyan Kara group and underlying formations.

  15. A novel branched side-chain-type sulfonated polyimide membrane with flexible sulfoalkyl pendants and trifluoromethyl groups for vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Li, Jinchao; Liu, Suqin; He, Zhen; Zhou, Zhi

    2017-04-01

    A novel branched side-chain-type sulfonated polyimide (6F-s-bSPI) membrane with accessible branching agents of melamine, hydrophobic trifluoromethyl groups (sbnd CF3), and flexible sulfoalkyl pendants is prepared by a high-temperature polycondensation and post-sulfonation method for use in vanadium redox flow batteries (VRFBs). The chemical structure of the 6F-s-bSPI membrane is confirmed by ATR-FTIR and 1H NMR spectra. The physico-chemical properties of the as-prepared 6F-s-bSPI membrane are systematically investigated and found to be strongly related to the specially designed structure. The 6F-s-bSPI membrane offers a reduced cost and possesses a significantly lowered vanadium ion permeability (1.18 × 10-7 cm2 min-1) compared to the linear SPI (2.25 × 10-7 cm2 min-1) and commercial Nafion 115 (1.36 × 10-6 cm2 min-1) membranes, prolonging the self-discharge duration of the VRFBs. In addition, the VRFB assembled with a 6F-s-bSPI membrane shows higher coulombic (98.3%-99.7%) and energy efficiencies (88.4%-66.12%) than that with a SPI or Nafion 115 membrane under current densities ranging from 20 to 100 mA cm-2. Moreover, the VRFB with a 6F-s-bSPI membrane delivers a stable cycling performance over 100 cycles with no decline in coulombic and energy efficiencies. These results show that the branched side-chain-type structure is a promising design to prepare excellent proton conductive membranes.

  16. Potentiation of acid-sensing ion channel activity by peripheral group I metabotropic glutamate receptor signaling.

    PubMed

    Gan, Xiong; Wu, Jing; Ren, Cuixia; Qiu, Chun-Yu; Li, Yan-Kun; Hu, Wang-Ping

    2016-05-01

    Glutamate activates peripheral group I metabotropic glutamate receptors (mGluRs) and contributes to inflammatory pain. However, it is still not clear the mechanisms are involved in group I mGluR-mediated peripheral sensitization. Herein, we report that group I mGluRs signaling sensitizes acid-sensing ion channels (ASICs) in dorsal root ganglion (DRG) neurons and contributes to acidosis-evoked pain. DHPG, a selective group I mGluR agonist, can potentiate the functional activity of ASICs, which mediated the proton-induced events. DHPG concentration-dependently increased proton-gated currents in DRG neurons. It shifted the proton concentration-response curve upwards, with a 47.3±7.0% increase of the maximal current response to proton. Group I mGluRs, especially mGluR5, mediated the potentiation of DHPG via an intracellular cascade. DHPG potentiation of proton-gated currents disappeared after inhibition of intracellular Gq/11 proteins, PLCβ, PKC or PICK1 signaling. Moreover, DHPG enhanced proton-evoked membrane excitability of rat DRG neurons and increased the amplitude of the depolarization and the number of spikes induced by acid stimuli. Finally, peripherally administration of DHPG dose-dependently exacerbated nociceptive responses to intraplantar injection of acetic acid in rats. Potentiation of ASIC activity by group I mGluR signaling in rat DRG neurons revealed a novel peripheral mechanism underlying group I mGluRs involvement in hyperalgesia.

  17. Harnessing Yeast Peroxisomes for Biosynthesis of Fatty-Acid-Derived Biofuels and Chemicals with Relieved Side-Pathway Competition.

    PubMed

    Zhou, Yongjin J; Buijs, Nicolaas A; Zhu, Zhiwei; Gómez, Diego Orol; Boonsombuti, Akarin; Siewers, Verena; Nielsen, Jens

    2016-11-30

    Establishing efficient synthetic pathways for microbial production of biochemicals is often hampered by competing pathways and/or insufficient precursor supply. Compartmentalization in cellular organelles can isolate synthetic pathways from competing pathways, and provide a compact and suitable environment for biosynthesis. Peroxisomes are cellular organelles where fatty acids are degraded, a process that is inhibited under typical fermentation conditions making them an interesting workhouse for production of fatty-acid-derived molecules. Here, we show that targeting synthetic pathways to peroxisomes can increase the production of fatty-acid-derived fatty alcohols, alkanes and olefins up to 700%. In addition, we demonstrate that biosynthesis of these chemicals in the peroxisomes results in significantly decreased accumulation of byproducts formed by competing enzymes. We further demonstrate that production can be enhanced up to 3-fold by increasing the peroxisome population. The strategies described here could be used for production of other chemicals, especially acyl-CoA-derived molecules.

  18. Anxiolytic and side-effect profile of LY354740: a potent, highly selective, orally active agonist for group II metabotropic glutamate receptors.

    PubMed

    Helton, D R; Tizzano, J P; Monn, J A; Schoepp, D D; Kallman, M J

    1998-02-01

    LY354740 is a conformationally constrained analog of glutamate which is a potent agonist for group II cAMP coupled metabotropic glutamate receptors (mGluRs). The discovery of this novel pharmacological agent has allowed the exploration of the functional consequences of activating group II mGluRs in vivo. In an effort to evaluate the clinical utility of LY354740 as an anxiolytic, we examined its effects in the fear potentiated startle and elevated plus maze models of anxiety and compared the results with the clinically prescribed anxiolytic diazepam. In the fear potentiated startle and elevated plus maze models, both LY354740 and diazepam produced significant anxiolytic activity (ED50 values of 0.3 and 0.4 mg/kg p. o. for fear potentiated startle and 0.2 and 0.5 mg/kg for the elevated plus maze, respectively). The duration of pharmacological effect for LY354740 in the efficacy models was 4 to 8 hr. In contrast to diazepam, acute administration of LY354740 did not produce sedation, cause deficits in neuromuscular coordination, interact with central nervous system depressants, produce memory impairment or change convulsive thresholds at doses 100- to 1000-fold the efficacious doses in animal models of anxiety. Thus, LY354740 has anxiolytic activity in animal models that are sensitive to benzodiazepines such as diazepam. However, at anxiolytic doses in these models, LY354740 produced none of the unwanted secondary pharmacology associated with diazepam. These data indicate a functional role for group II mGluRs in fear/anxiety responses in animals and suggest that compounds in this class may be beneficial in the treatment of anxiety-related disorders in humans without the side effects seen with currently prescribed medications.

  19. Neogene transpressional foreland basin development on the north side of the central alaska range, usibelli group and nenana gravel, tanana basin

    USGS Publications Warehouse

    Ridgway, K.D.; Thoms, E.E.; Layer, P.W.; Lesh, M.E.; White, J.M.; Smith, S.V.

    2007-01-01

    Neogene strata of the Tanana basin provide a long-term record of a northwardpropagating, transpressional foreland-basin system related to regional shortening of the central Alaska Range and strike-slip displacement on the Denali fault system. These strata are ???2 km thick and have been deformed and exhumed in thrust faults that form the foothills on the north side of the Alaska Range. The lower part of the sedimentary package, the Usibelli Group, consists of 800 m of mainly Miocene strata that were deposited in fluvial, lacustrine, and peat bog environments of the foredeep depozone of the foreland-basin system. Compositional data from conglomerate and sandstone, as well as recycled Upper Cretaceous palynomorphs, indicate that the Miocene foreland-basin system was supplied increasing amounts of sediment from lithologies currently exposed in thrust sheets located south of the basin. The upper part of the sedimentary package, the Nenana Gravel, consists of 1200 m of mainly Pliocene strata that were deposited in alluvial-fan and braidplain environments in the wedge-top depozone of the foreland-basin system. Compositional data from conglomerate and sandstone, as well as 40Ar/39Ar dating of detrital feldspars in sandstone and from granitic clasts in conglomerate, indicate that lithologies exposed in the central Alaska Range provided most of the detritus to the Pliocene foreland-basin system. 40Ar/39Ar dates from detrital feldspar grains also show that two main suites of plutons contributed sediment to the Nenana Gravel. Detrital feldspars with an average age of 56 Ma are interpreted to have been derived from the McKinley sequence of plutons located south of the Denali fault. Detrital feldspars with an average age of 34 Ma are interpreted to have been derived from plutons located north of the Denali fault. Plutons located south of the Denali fault provided detritus for the lower part of the Nenana Gravel, whereas plutons located north of the Denali fault began to

  20. A new sesquiterpene lactone with sulfonic acid group from Saussurea lappa.

    PubMed

    Yin, Hong-Quan; Hua, Hui-Ming; Fu, Hong-Wei; Qi, Xiu-Lan; Li, Wen; Sha, Yi; Pei, Yue-Hu

    2007-01-01

    A new sesquiterpene lactone with an unusual sulfonic acid group, 13-sulfo-dihydrodehydrocostus lactone (1), was isolated from the roots of Saussurea lappa C. (Compositae), together with a known lignan (2). The structure of 1 was characterized on the basis of spectral evidence including 2DNMR studies. Compound 2 was obtained from this plant for the first time.

  1. Two new sesquiterpene lactones with the sulfonic acid group from Saussurea lappa.

    PubMed

    Yin, Hong-quan; Fu, Hong-wei; Hua, Hui-ming; Qi, Xiu-lan; Li, Wen; Sha, Yi; Pei, Yue-hu

    2005-07-01

    Two new sesquiterpene lactones with the unusual sulfonic acid group, 13-sulfo-dihydrosantamarine (1) and 13-sulfo-dihydroreynosin (2), have been isolated from the roots of Saussurea lappa C. Their structures, including the absolute configurations, were elucidated by spectroscopic methods.

  2. Development of Acid Functional Groups and Lactones During the Thermal Degradation of Wood and Wood Components

    USGS Publications Warehouse

    Rutherford, David W.; Wershaw, Robert L.; Reeves, James B.

    2008-01-01

    Black carbon (pyrogenic materials including chars) in soils has been recognized as a substantial portion of soil organic matter, and has been shown to play a vital role in nutrient cycling; however, little is known concerning the properties of this material. Previous studies have largely been concerned with the creation of high-surface-area materials for use as sorbents. These materials have been manufactured at high temperature and have often been activated. Chars occurring in the environment can be formed over a wide range of temperature. Because it is extremely difficult to isolate black carbon once it has been incorporated in soils, chars produced in the laboratory under controlled conditions can be used to investigate the range of properties possible for natural chars. This report shows that charring conditions (temperature and time) have substantial impact on the acid functional group and lactone content of chars. Low temperatures (250?C) and long charring times (greater than 72 hours) produce chars with the highest acid functional group and lactone content. The charring of cellulose appears to be responsible for the creation of the acid functional group and lactones. The significance of this study is that low-temperature chars can have acid functional group contents comparable to humic materials (as high as 8.8 milliequivalents per gram). Acid functional group and lactone content decreases as charring temperature increases. The variation in formation conditions expected under natural fire conditions will result in a wide range of sorption properties for natural chars which are an important component of soil organic matter. By controlling the temperature and duration of charring, it is possible to tailor the sorption properties of chars, which may be used as soil amendments.

  3. Binding of amino acid side chains to preformed cavities: interaction of serine proteinases with turkey ovomucoid third domains with coded and noncoded P1 residues.

    PubMed Central

    Bigler, T. L.; Lu, W.; Park, S. J.; Tashiro, M.; Wieczorek, M.; Wynn, R.; Laskowski, M.

    1993-01-01

    In the association of serine proteinases with their cognate substrates and inhibitors an important interaction is the fitting of the P1 side chain of the substrate or inhibitor into a preformed cavity of the enzyme called the S1 pocket. In turkey ovomucoid third domain, which is a canonical protein proteinase inhibitor, the P1 residue is Leu18. Here we report the values of equilibrium constants, Ka, for turkey ovomucoid third domain and 13 additional Leu18X variants with six serine proteinases: bovine alpha chymotrypsin A, porcine pancreatic elastase, subtilisin Carlsberg, Streptomyces griseus proteinases A and B, and human leukocyte elastase. Eight of the Xs are coded amino acids: Ala, Ser, Val, Met, Gln, Glu, Lys, and Phe, and five are noncoded: Abu, Ape, Ahx, Ahp, and Hse. They were chosen to simplify the interamino acid comparisons. In the homologous series of straight-chain side chains Ala, Abu, Ape, Ahx, Ahp, free energy of binding decreases monotonically with the side-chain length for chymotrypsin with large binding pocket, but even for this enzyme shows curvature. For the two S. griseus enzymes a minimum appears to be reached at Ahp. A minimum is clearly evident for the two elastases, where increasing the side-chain length from Ahx to Ahp greatly weakens binding, but much more so for the apparently more rigid pancreatic enzyme than for the more flexible leukocyte enzyme. beta-Branching (Ape/Val) is very deleterious for five of the six enzymes; it is only slightly deleterious for the more flexible human leukocyte elastase. The effect of gamma-branching (Ahx/Leu), of introduction of heteroatoms (Abu/Ser), (Ape/Hse), and (Ahx/Met), and of introduction of charge (Gln/Glu) and (Ahp/Lys) are tabulated and discussed. An important component of the free energy of interaction is the distortion of the binding pocket by bulky or branched side chains. Most of the variants studied were obtained by enzymatic semisynthesis. X18 variants of the 6-18 peptide GlyNH2 were

  4. Association between the frequency of meals combining "Shushoku, Shusai, and Hukusai" (Staple food, main dish, and side dish) and intake of nutrients and food groups among Japanese young adults aged 18-24 years: a cross-sectional study.

    PubMed

    Kakutani, Yuya; Kamiya, Saori; Omi, Naomi

    2015-01-01

    "Shushoku," "Shusai," and "Hukusai" are staple food, main dish, and side dish, respectively. The recommended meal in Japan is a combination of "Shushoku," "Shusai," and "Hukusai"; however, it remains unclear whether there is an association between the frequency of these meals and intake of nutrients and food groups. This cross-sectional study examined the association between the frequency of meals combining "Shushoku, Shusai, and Hukusai" and intake of nutrients and food groups among 664 Japanese young adults aged 18-24 y. The dietary habits of the subjects during the preceding month were assessed using a validated brief-type self-administered diet history questionnaire. The frequency of meals combining "Shushoku, Shusai, and Hukusai" was self-reported according to four categories: "less than 1 d or 1 d/wk," "2 or 3 d/wk," "4 or 5 d/wk," and "every day." In both women and men, there was an association between the higher frequency of these meals and higher intake of the following food groups: pulses, green and yellow vegetables, other vegetables, mushrooms, seaweeds, fish and shellfish, and eggs. Moreover, there was an association with higher intake of protein, polyunsaturated fat, n-6 and n-3 polyunsaturated fat, total dietary fiber, soluble and insoluble dietary fiber, β-carotene, α-tocopherol, vitamin K, thiamin, riboflavin, folate, pantothenic acid, vitamin C, potassium, calcium, magnesium, iron, and copper, and lower intake of carbohydrate in both women and men. Our findings support the hypothesis that the meals combining "Shushoku, Shusai, and Hukusai" may be associated with intake of many food groups and nutrients among Japanese young adults.

  5. The role of the amino acid-derived side chain in the preorganization of C₂-symmetric pseudopeptides: effect on S(N)2 macrocyclization reactions.

    PubMed

    Martí-Centelles, Vicente; Burguete, M Isabel; Cativiela, Carlos; Luis, Santiago V

    2014-01-17

    A family of pseudopeptidic macrocycles containing non-natural amino acids have been synthesized. The macrocyclization reaction has been studied experimentally and computationally, demonstrating the key role of both the amino acid side chain and the catalytic bromide anion. The bromide anion acts as an external template assisting the folding of the open-chain precursor in a proper conformation. Computations revealed that in the presence of the anion, the effect of the side chain on the energy barrier for the macrocyclization is very small. However, the effect on the conformational equilibria of the open-chain precursors is very important. Overall, the stabilization of those conformation(s) in which the two reactive ends of the open-chain intermediate are located at short distances from each other with the correct orientation is the critical parameter defining the success of the macrocyclization. The best yield was found for the compound containing cyclohexylalanine, for which the computationally-predicted most stable conformer in the presence of Br(-) has a proper preorganization for cyclization. The remarkable agreement obtained between experiments and theory reveals that the computational approach here considered can be of great utility for the prediction of the behavior of other related systems and for the design of appropriate synthetic routes to new macrocyclic compounds.

  6. Predicting the acidity constant of a goethite hydroxyl group from first principles

    NASA Astrophysics Data System (ADS)

    Leung, Kevin; Criscenti, Louise J.

    2012-03-01

    Accurate predictions of the acid-base behavior of hydroxyl groups at mineral surfaces are critical for understanding the trapping of toxic and radioactive ions in soil samples. In this work, we apply ab initio molecular dynamics (AIMD) simulations and potential-of-mean-force techniques to calculate the pKa of a doubly protonated oxygen atom bonded to a single Fe atom (FeIOH2) on the goethite (101) surface. Using formic acid as a reference system, pKa = 7.0 is predicted, suggesting that isolated, positively charged groups of this type are marginally stable at neutral pH. Similarities and differences between AIMD and the more empirical multi-site complexation methodology are highlighted, particularly with respect to the treatment of hydrogen bonding with water and proton sharing among surface hydroxyl groups. We also highlight the importance of an electronic structure method that can accurately predict transition metal ion properties for goethite pKa calculations.

  7. Solid phase synthesis of partially protected tocinoic acid: optimization with respect to resin and protecting groups.

    PubMed

    Hlavácek, J; Ragnarsson, U

    2001-07-01

    A few solid phase and solution approaches of good repute were applied in parallel with the aim to provide optimized routes to Boc- and Fmoc-tocinoic acid (3a and 3c) and the corresponding Tyr(Bu(t)) derivatives (3b and 3d). Boc-tocinoic acid is known to couple with tripeptide amides to give substituted oxytocin precursors in high yields, requiring only Boc-cleavage to furnish the corresponding hormone analogs with minimal loss of material. For comparison, two protected linear hexapeptides (2a and 2b) were prepared on three polystyrene supports, two with acid-labile handles and one a conventional chloromethylated resin, in yields of 62-82 and 58-76%, respectively. The intermediate 2a could be converted to 3a with physical data in agreement with those earlier reported. Similarly, the intermediate 2b was converted to 3b. The highest yields for both 2a and 2b were obtained with a 2-chlorotrityl chloride resin, which in addition provided advantages with respect to overall speed and convenience. Additional syntheses of 3c and 3d on this and of 3c on SASRIN resin, in conjunction with trityl instead of benzyl for side-chain protection of cysteine, were also elaborated.

  8. Full Fatty Acid Amide Hydrolase Inhibition Combined with Partial Monoacylglycerol Lipase Inhibition: Augmented and Sustained Antinociceptive Effects with Reduced Cannabimimetic Side Effects in Mice

    PubMed Central

    Ghosh, Sudeshna; Kinsey, Steven G.; Liu, Qing-song; Hruba, Lenka; McMahon, Lance R.; Grim, Travis W.; Merritt, Christina R.; Wise, Laura E.; Abdullah, Rehab A.; Selley, Dana E.; Sim-Selley, Laura J.; Cravatt, Benjamin F.

    2015-01-01

    Inhibition of fatty acid amide hydrolase (FAAH) or monoacylglycerol lipase (MAGL), the primary hydrolytic enzymes for the respective endocannabinoids N-arachidonoylethanolamine (AEA) and 2-arachidonylglycerol (2-AG), produces antinociception but with minimal cannabimimetic side effects. Although selective inhibitors of either enzyme often show partial efficacy in various nociceptive models, their combined blockade elicits augmented antinociceptive effects, but side effects emerge. Moreover, complete and prolonged MAGL blockade leads to cannabinoid receptor type 1 (CB1) receptor functional tolerance, which represents another challenge in this potential therapeutic strategy. Therefore, the present study tested whether full FAAH inhibition combined with partial MAGL inhibition would produce sustained antinociceptive effects with minimal cannabimimetic side effects. Accordingly, we tested a high dose of the FAAH inhibitor PF-3845 (N-​3-​pyridinyl-​4-​[[3-​[[5-​(trifluoromethyl)-​2-​pyridinyl]oxy]phenyl]methyl]-​1-​piperidinecarboxamide; 10 mg/kg) given in combination with a low dose of the MAGL inhibitor JZL184 [4-nitrophenyl 4-(dibenzo[d][1,3]dioxol-5-yl(hydroxy)methyl)piperidine-1-carboxylate] (4 mg/kg) in mouse models of inflammatory and neuropathic pain. This combination of inhibitors elicited profound increases in brain AEA levels (>10-fold) but only 2- to 3-fold increases in brain 2-AG levels. This combination produced significantly greater antinociceptive effects than single enzyme inhibition and did not elicit common cannabimimetic effects (e.g., catalepsy, hypomotility, hypothermia, and substitution for Δ9-tetrahydrocannabinol in the drug-discrimination assay), although these side effects emerged with high-dose JZL184 (i.e., 100 mg/kg). Finally, repeated administration of this combination did not lead to tolerance to its antiallodynic actions in the carrageenan assay or CB1 receptor functional tolerance. Thus, full FAAH inhibition combined

  9. Rh(III)-catalyzed synthesis of sultones through C-H activation directed by a sulfonic acid group.

    PubMed

    Qi, Zisong; Wang, Mei; Li, Xingwei

    2014-09-04

    A new rhodium-catalyzed synthesis of sultones via the oxidative coupling of sulfonic acids with internal alkynes is described. The reaction proceeds via aryl C-H activation assisted by a sulfonic acid group.

  10. Activation of carboxyl group with cyanate: peptide bond formation from dicarboxylic acids.

    PubMed

    Danger, Grégoire; Charlot, Solenne; Boiteau, Laurent; Pascal, Robert

    2012-06-01

    The reaction of cyanate with C-terminal carboxyl groups of peptides in aqueous solution was considered as a potential pathway for the abiotic formation of peptide bonds under the condition of the primitive Earth. The catalytic effect of dicarboxylic acids on cyanate hydrolysis was definitely attributed to intramolecular nucleophilic catalysis by the observation of the 1H-NMR signal of succinic anhydride when reacting succinic acid with KOCN in aqueous solution (pH 2.2-5.5). The formation of amide bonds was noticed when adding amino acids or amino acid derivatives into the solution. The reaction of N-acyl aspartic acid derivatives was observed to proceed similarly and the scope of the cyanate-promoted reaction was analyzed from the standpoint of prebiotic peptide formation. The role of cyanate in activating peptide C-terminus constitutes a proof of principle that intramolecular reactions of adducts of peptides C-terminal carboxyl groups with activating agents represent a pathway for peptide activation in aqueous solution, the relevance of which is discussed in connexion with the issue of the emergence of homochirality.

  11. Main Group Lewis Acid-Mediated Transformations of Transition-Metal Hydride Complexes.

    PubMed

    Maity, Ayan; Teets, Thomas S

    2016-08-10

    This Review highlights stoichiometric reactions and elementary steps of catalytic reactions involving cooperative participation of transition-metal hydrides and main group Lewis acids. Included are reactions where the transition-metal hydride acts as a reactant as well as transformations that form the metal hydride as a product. This Review is divided by reaction type, illustrating the diverse roles that Lewis acids can play in mediating transformations involving transition-metal hydrides as either reactants or products. We begin with a discussion of reactions where metal hydrides form direct adducts with Lewis acids, elaborating the structure and dynamics of the products of these reactions. The bulk of this Review focuses on reactions where the transition metal and Lewis acid act in cooperation, and includes sections on carbonyl reduction, H2 activation, and hydride elimination reactions, all of which can be promoted by Lewis acids. Also included is a section on Lewis acid-base secondary coordination sphere interactions, which can influence the reactivity of hydrides. Work from the past 50 years is included, but the majority of this Review focuses on research from the past decade, with the intent of showcasing the rapid emergence of this field and the potential for further development into the future.

  12. In silico modification of Zn2+ binding group of suberoylanilide hydroxamic acid (SAHA) by organoselenium compounds as Homo sapiens class II HDAC inhibitor of cervical cancer

    NASA Astrophysics Data System (ADS)

    Sumo Friend Tambunan, Usman; Bakri, Ridla; Aditya Parikesit, Arli; Ariyani, Titin; Dyah Puspitasari, Ratih; Kerami, Djati

    2016-02-01

    Cervical cancer is the most common cancer in women, and ranks seventh of all cancers worldwide, with 529000 cases in 2008 and more than 85% cases occur in developing countries. One way to treat this cancer is through the inhibition of HDAC enzymes which play a strategic role in the regulation of gene expression. Suberoyl Anilide Hydroxamic Acid (SAHA) or Vorinostat is a drug which commercially available to treat the cancer, but still has some side effects. This research present in silico SAHA modification in Zinc Binding Group (ZBG) by organoselenium compound to get ligands which less side effect. From molecular docking simulation, and interaction analysis, there are five best ligands, namely CC27, HA27, HB28, IB25, and KA7. These five ligands have better binding affinity than the standards, and also have interaction with Zn2+ cofactor of inhibited HDAC enzymes. This research is expected to produce more potent HDAC inhibitor as novel drug for cervical cancer treatment.

  13. Boronic Acid Group: A Cumbersome False Negative Case in the Process of Drug Design.

    PubMed

    Katsamakas, Sotirios; Papadopoulos, Anastasios G; Hadjipavlou-Litina, Dimitra

    2016-09-07

    Herein we present, an exhaustive docking analysis considering the case of autotaxin (ATX). HA155, a small molecule inhibitor of ATX, is co-crystallized. In order to further extract conclusions on the nature of the bond formed between the ligands and the amino acid residues of the active site, density functional theory (DFT) calculations were undertaken. However, docking does not provide reproducible results when screening boronic acid derivatives and their binding orientations to protein drug targets. Based on natural bond orbital (NBO) calculations, the formed bond between Ser/Thr residues is characterized more accurately as a polar covalent bond instead of a simple nonpolar covalent one. The presented results are acceptable and could be used in screening as an active negative filter for boron compounds. The hydroxyl groups of amino acids are bonded with the inhibitor's boron atom, converting its hybridization to sp³.

  14. Conjugation of bioactive groups to poly(lactic acid) and poly[(lactic acid)-co-(glycolic acid)] films.

    PubMed

    Prime, Emma L; Cooper-White, Justin J; Qiao, Greg G

    2007-12-06

    A novel PLA-based polymer containing reactive pendent ketone or hydroxyl groups was synthesized by the copolymerization of L-lactide with epsilon-caprolactone-based monomers. The polymer was activated with NPC, resulting in an amine-reactive polymer which was then cast into thin polymeric films, either alone or as part of a blend with PLGA, before immersion into a solution of the cell adhesion peptide GRGDS in PBS buffer allowed for conjugation of GRGDS to the film surfaces. Subsequent 3T3 fibroblast cell adhesion studies demonstrated an increase in cellular adhesion and spreading over films cast from unmodified PLGA. Hence the new polymer can be used to obtain covalent linkage of amine-containing molecules to polymer surfaces.

  15. H-binding groups in lignite vs. soil humic acids: NICA-Donnan and spectroscopic parameters

    SciTech Connect

    Drosos, M.; Jerzykiewicz, M.; Deligiannakis, Y.

    2009-04-15

    A comparative study has been carried out for two sets of humic acids isolated from lignites and soils. H-binding data were analyzed using the NICA-Donnan model, for three Greek lignite humic acids (HA) plus IHSS Leonardite reference HA, and five Greek soil HAs plus a commercial peat HA. {sup 13}C-CP-MAS NMR and H-binding data provide quantitative estimates for functional groups, showing that lignite HAs of diverse origin have strikingly homogeneous properties, while the H-binding structural units of soil HAs are characterized by a large degree of variability. Consistent differences between soil HA vs. lignite HA are revealed at the level of functional groups' concentrations. In the pH range 4 to 10, soil HA showed a charge variation < 3 (equiv kg{sup -1}) while lignite HAs showed a higher charge variation > 3.5 (equiv kg{sup -1}).

  16. Block copolymer micelles with acid-labile ortho ester side-chains: Synthesis, characterization, and enhanced drug delivery to human glioma cells.

    PubMed

    Tang, Rupei; Ji, Weihang; Panus, David; Palumbo, R Noelle; Wang, Chun

    2011-04-10

    A new type of block copolymer micelles for pH-triggered delivery of poorly water-soluble anticancer drugs has been synthesized and characterized. The micelles were formed by the self-assembly of an amphiphilic diblock copolymer consisting of a hydrophilic poly(ethylene glycol) (PEG) block and a hydrophobic polymethacrylate block (PEYM) bearing acid-labile ortho ester side-chains. The diblock copolymer was synthesized by atom transfer radical polymerization (ATRP) from a PEG macro-initiator to obtain well-defined polymer chain-length. The PEG-b-PEYM micelles assumed a stable core-shell structure in aqueous buffer at physiological pH with a low critical micelle concentration as determined by proton NMR and pyrene fluorescence spectroscopy. The hydrolysis of the ortho ester side-chain at physiological pH was minimal yet much accelerated at mildly acidic pHs. Doxorubicin (Dox) was successfully loaded into the micelles at pH 7.4 and was released at a much higher rate in response to slight acidification to pH 5. Interestingly, the release of Dox at pH 5 followed apparently a biphasic profile, consisting of an initial fast phase of several hours followed by a sustained release period of several days. Dox loaded in the micelles was rapidly taken up by human glioma (T98G) cells in vitro, accumulating in the endolysosome and subsequently in the nucleus in a few hours, in contrast to the very low uptake of free drug at the same dose. The dose-dependent cytotoxicity of the Dox-loaded micelles was determined by the MTT assay and compared with that of the free Dox. While the empty micelles themselves were not toxic, the IC(50) values of the Dox-loaded micelles were approximately ten-times (by 24h) and three-times (by 48h) lower than the free drug. The much enhanced potency in killing the multi-drug-resistant human glioma cells by Dox loaded in the micelles could be attributed to high intracellular drug concentration and the subsequent pH-triggered drug release. These results

  17. Removal of transition metals from dilute aqueous solution by carboxylic acid group containing absorbent polymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new carboxylic acid group containing resin with cation exchange capacity, 12.67 meq/g has been used to remove Cu2+, Co2+ and Ni2+ ions from dilute aqueous solution. The resin has Cu2+, Co2+ and Ni2+ removal capacity, 216 mg/g, 154 mg/g and 180 mg/g, respectively. The selectivity of the resin to ...

  18. Photoinduced electron transfer involving eosin-tryptophan conjugates. Long-lived radical pair states for systems incorporating aromatic amino acid side chains

    SciTech Connect

    Jones, G. II; Farahat, C.W.; Oh, C. )

    1994-07-14

    The electron-transfer photochemistry of the covalent derivatives of the dye eosin, in which the xanthene dye is covalently attached to the amino acid L-tryptophan via the thiohydantoin derivative, the tryptophan dipeptide, and an ethyl ester derivative, has been investigated. The singlet excited state of the dye is significantly quenched on attachment of the aromatic amino acid residue. Dye triplet states are also intercepted through intramolecular interaction of excited dye and amino acid pendants. Flash photolysis experiments verify that this interaction involves electron transfer from the indole side chains of tryptophan. Rate constants for electron transfer are discussed in terms of the distance relationships for the eosin chromophore and aromatic redox sites on peptide derivatives, the pathway for [sigma]-[pi] through-bond interaction between redox sites, and the multiplicity and state of protonation for electron-transfer intermediates. Selected electron-transfer photoreactions were studied under conditions of binding of the peptide derivatives in a high molecular weight, water-soluble, globular polymer, poly(vinyl-2-pyrrolidinone). 28 refs., 4 figs., 1 tab.

  19. Rh(III)-catalyzed decarboxylative ortho-heteroarylation of aromatic carboxylic acids by using the carboxylic acid as a traceless directing group.

    PubMed

    Qin, Xurong; Sun, Denan; You, Qiulin; Cheng, Yangyang; Lan, Jingbo; You, Jingsong

    2015-04-03

    Highly selective decarboxylative ortho-heteroarylation of aromatic carboxylic acids with various heteroarenes has been developed through Rh(III)-catalyzed two-fold C-H activation, which exhibits a wide substrate scope of both aromatic carboxylic acids and heteroarenes. The use of naturally occurring carboxylic acid as the directing group avoids troublesome extra steps for installation and removal of an external directing group.

  20. Active-Site Engineering of ω-Transaminase for Production of Unnatural Amino Acids Carrying a Side Chain Bulkier than an Ethyl Substituent

    PubMed Central

    Han, Sang-Woo; Park, Eul-Soo; Dong, Joo-Young

    2015-01-01

    ω-Transaminase (ω-TA) is a promising enzyme for use in the production of unnatural amino acids from keto acids using cheap amino donors such as isopropylamine. The small substrate-binding pocket of most ω-TAs permits entry of substituents no larger than an ethyl group, which presents a significant challenge to the preparation of structurally diverse unnatural amino acids. Here we report on the engineering of an (S)-selective ω-TA from Ochrobactrum anthropi (OATA) to reduce the steric constraint and thereby allow the small pocket to readily accept bulky substituents. On the basis of a docking model in which l-alanine was used as a ligand, nine active-site residues were selected for alanine scanning mutagenesis. Among the resulting variants, an L57A variant showed dramatic activity improvements in activity for α-keto acids and α-amino acids carrying substituents whose bulk is up to that of an n-butyl substituent (e.g., 48- and 56-fold increases in activity for 2-oxopentanoic acid and l-norvaline, respectively). An L57G mutation also relieved the steric constraint but did so much less than the L57A mutation did. In contrast, an L57V substitution failed to induce the improvements in activity for bulky substrates. Molecular modeling suggested that the alanine substitution of L57, located in a large pocket, induces an altered binding orientation of an α-carboxyl group and thereby provides more room to the small pocket. The synthetic utility of the L57A variant was demonstrated by carrying out the production of optically pure l- and d-norvaline (i.e., enantiomeric excess [ee] > 99%) by asymmetric amination of 2-oxopantanoic acid and kinetic resolution of racemic norvaline, respectively. PMID:26231640

  1. Mathematical Characterization of Protein Sequences Using Patterns as Chemical Group Combinations of Amino Acids.

    PubMed

    Das, Jayanta Kumar; Das, Provas; Ray, Korak Kumar; Choudhury, Pabitra Pal; Jana, Siddhartha Sankar

    2016-01-01

    Comparison of amino acid sequence similarity is the fundamental concept behind the protein phylogenetic tree formation. By virtue of this method, we can explain the evolutionary relationships, but further explanations are not possible unless sequences are studied through the chemical nature of individual amino acids. Here we develop a new methodology to characterize the protein sequences on the basis of the chemical nature of the amino acids. We design various algorithms for studying the variation of chemical group transitions and various chemical group combinations as patterns in the protein sequences. The amino acid sequence of conventional myosin II head domain of 14 family members are taken to illustrate this new approach. We find two blocks of maximum length 6 aa as 'FPKATD' and 'Y/FTNEKL' without repeating the same chemical nature and one block of maximum length 20 aa with the repetition of chemical nature which are common among all 14 members. We also check commonality with another motor protein sub-family kinesin, KIF1A. Based on our analysis we find a common block of length 8 aa both in myosin II and KIF1A. This motif is located in the neck linker region which could be responsible for the generation of mechanical force, enabling us to find the unique blocks which remain chemically conserved across the family. We also validate our methodology with different protein families such as MYOI, Myosin light chain kinase (MLCK) and Rho-associated protein kinase (ROCK), Na+/K+-ATPase and Ca2+-ATPase. Altogether, our studies provide a new methodology for investigating the conserved amino acids' pattern in different proteins.

  2. Preparation of the very acid-sensitive Fmoc-Lys(Mtt)-OH. Application in the synthesis of side-chain to side-chain cyclic peptides and oligolysine cores suitable for the solid-phase assembly of MAPs and TASPs.

    PubMed

    Aletras, A; Barlos, K; Gatos, D; Koutsogianni, S; Mamos, P

    1995-05-01

    N alpha-9-Fluorenylmethoxycarbonyl-N epsilon-4=methyltrityl-lysine, [Fmoc-Lys(Mtt)-OH], was prepared in two steps from lysine, in 42% overall yield. The N epsilon-Mtt function can be quantitatively removed upon treatment with 1% TFA in dichloromethane or with a 1:2:7 mixture of acetic acid/trifluoroethanol/dichloromethane for 30 min and 1 h at room temperature, respectively. Under these conditions, groups of the tert-butyl type and peptide ester bonds to TFA-labile resins, such as the 2-chlorodiphenylmethyl- and the Wang-resin, remained intact. The utility of the new derivative in peptide synthesis has been exemplified with the synthesis of a cyclic cholecystokinin analog. As an example of further application, five types of lysine cores suitable for the solid-phase synthesis of one, two or three epitopes containing antigenic peptides or template-assembled synthetic proteins have been synthesized on Merrifield, Wang and 2-chlorodiphenylmethyl resin.

  3. Lactic acid bacteria producing B-group vitamins: a great potential for functional cereals products.

    PubMed

    Capozzi, Vittorio; Russo, Pasquale; Dueñas, María Teresa; López, Paloma; Spano, Giuseppe

    2012-12-01

    Wheat contains various essential nutrients including the B group of vitamins. However, B group vitamins, normally present in cereals-derived products, are easily removed or destroyed during milling, food processing or cooking. Lactic acid bacteria (LAB) are widely used as starter cultures for the fermentation of a large variety of foods and can improve the safety, shelf life, nutritional value, flavor and overall quality of the fermented products. In this regard, the identification and application of strains delivering health-promoting compounds is a fascinating field. Besides their key role in food fermentations, several LAB found in the gastrointestinal tract of humans and animals are commercially used as probiotics and possess generally recognized as safe status. LAB are usually auxotrophic for several vitamins although certain strains of LAB have the capability to synthesize water-soluble vitamins such as those included in the B group. In recent years, a number of biotechnological processes have been explored to perform a more economical and sustainable vitamin production than that obtained via chemical synthesis. This review article will briefly report the current knowledge on lactic acid bacteria synthesis of vitamins B2, B11 and B12 and the potential strategies to increase B-group vitamin content in cereals-based products, where vitamins-producing LAB have been leading to the elaboration of novel fermented functional foods. In addition, the use of genetic strategies to increase vitamin production or to create novel vitamin-producing strains will be also discussed.

  4. Carboxylic acid functional group analysis using constant neutral loss scanning-mass spectrometry.

    PubMed

    Dron, Julien; Eyglunent, Gregory; Temime-Roussel, Brice; Marchand, Nicolas; Wortham, Henri

    2007-12-12

    The present study describes the development of a new analytical technique for the functional group determination of the carboxylic moiety using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS/MS) operated in the constant neutral loss scanning (CNLS) mode. Carboxylic groups were first derivatized into their corresponding methyl esters by reacting with BF3/methanol mix and the reaction mixture was then directly injected into the APCI chamber. The loss of methanol (m/z = 32 amu) resulting from the fragmentation of the protonated methyl esters was then monitored. Applying this method together with a statistical approach to reference mixtures containing 31 different carboxylic acids at randomly calculated concentrations demonstrated its suitability for quantitative functional group measurements with relative standard deviations below 15% and a detection limit of 0.005 mmol L(-1). Its applicability to environmental matrices was also shown through the determination of carboxylic acid concentrations inside atmospheric aerosol samples. To the best of our knowledge, it is the first time that the tandem mass spectrometry was successfully applied to functional group analysis, offering great perspectives in the characterization of complex mixtures which are prevailing in the field of environmental analysis as well as in the understanding of the chemical processes occurring in these matrices.

  5. Partial amino acid sequences around sulfhydryl groups of soybean beta-amylase.

    PubMed

    Nomura, K; Mikami, B; Morita, Y

    1987-08-01

    Sulfhydryl (SH) groups of soybean beta-amylase were modified with 5-(iodoaceto-amidoethyl)aminonaphthalene-1-sulfonate (IAEDANS) and the SH-containing peptides exhibiting fluorescence were purified after chymotryptic digestion of the modified enzyme. The sequence analysis of the peptides derived from the modification of all SH groups in the denatured enzyme revealed the existence of six SH groups, in contrast to five reported previously. One of them was found to have extremely low reactivity toward SH-reagents without reduction. In the native state, IAEDANS reacted with 2 mol of SH groups per mol of the enzyme (SH1 and SH2) accompanied with inactivation of the enzyme owing to the modification of SH2 located near the active site of this enzyme. The selective modification of SH2 with IAEDANS was attained after the blocking of SH1 with 5,5'-dithiobis-(2-nitrobenzoic acid). The amino acid sequences of the peptides containing SH1 and SH2 were determined to be Cys-Ala-Asn-Pro-Gln and His-Gln-Cys-Gly-Gly-Asn-Val-Gly-Asp-Ile-Val-Asn-Ile-Pro-Ile-Pro-Gln-Trp, respectively.

  6. The GH67 α-glucuronidase of Paenibacillus curdlanolyticus B-6 removes hexenuronic acid groups and facilitates biodegradation of the model xylooligosaccharide hexenuronosyl xylotriose.

    PubMed

    Septiningrum, Krisna; Ohi, Hiroshi; Waeonukul, Rattiya; Pason, Patthra; Tachaapaikoon, Chakrit; Ratanakhanokchai, Khanok; Sermsathanaswadi, Junjarus; Deng, Lan; Prawitwong, Panida; Kosugi, Akihiko

    2015-04-01

    4-O-Methylglucuronic acid (MeGlcA) side groups attached to the xylan backbone through α-1,2 linkages are converted to hexenuronic acid (HexA) during alkaline pulping. α-Glucuronidase (EC 3.2.1.139) hydrolyzes 1,2-linked MeGlcA from xylooligosaccharides. To determine whether α-glucuronidase can also hydrolyze HexA-decorated xylooligosaccharides, a gene encoding α-glucuronidase (AguA) was cloned from Paenibacillus curdlanolyticus B-6. The purified protein degraded hexenuronosyl xylotriose (ΔX3), a model substrate prepared from kraft pulp. AguA released xylotriose and HexA from ΔX3, but the Vmax and kcat values for ΔX3 were lower than those for MeGlcA, indicating that HexA side groups may affect the hydrolytic activity. To explore the potential for biological bleaching, ΔX3 degradation was performed using intracellular extract from P. curdlanolyticus B-6. The intracellular extract, with synergistic α-glucuronidase and β-xylosidase activities, degraded ΔX3 to xylose and HexA. These results indicate that α-glucuronidase can be used to remove HexA from ΔX3 derived from pulp, reducing the need for chemical treatments in the pulping process.

  7. Synthesis and Monolayer Behaviors of Succinic Acid-Type Gemini Surfactants Containing Semifluoroalkyl Groups.

    PubMed

    Kawase, Tokuzo; Nagase, Youhei; Oida, Tatsuo

    2016-01-01

    In this work, novel succinic acid-type gemini surfactants containing semifluoroalkyl groups, dl- and meso-2,3-bis[Rf-(CH2)n]-succinic acids (Rf = C4F9, C6F13, C8F17; n = 2, 9), were successfully synthesized, and the effects of Rf, methylene chain length (n), and stereochemistry on their monolayer behaviors were studied. Critical micelle concentrations (CMC) of dl- and meso-2,3-bis[C4F9(CH2)9]-succinic acids were one order of magnitude smaller than that of the corresponding 1+1 type surfactant, C4F9(CH2)9COOH. From surface pressure-area (π-A) measurements, the lift-off areas of the geminis were found to decrease in the order C4F9 ≥ C6F13 > C8F17, regardless of methylene chain length and stereochemistry. The zero-pressure molecular areas of the geminis were twice those of the corresponding 1+1 type surfactants. Based on Gibbs compression modulus analysis, it was clarified that 2,3-bis[C8F17(CH2)n]-succinic gemini with short methylene chains (n = 2) would form more rigid monolayers than those having long methylene chains (n = 9). Unlike for 2,3-bis(alkyl)-succinic acids, the effects of stereochemistry on the monolayer behavior of semifluoroalkylated geminis were small.

  8. Simple Physics-Based Analytical Formulas for the Potentials of Mean Force of the Interaction of Amino Acid Side Chains in Water. VII. Charged-Hydrophobic/Polar and Polar-Hydrophobic/Polar Side Chains.

    PubMed

    Makowski, Mariusz; Liwo, Adam; Scheraga, Harold A

    2017-01-19

    The physics-based potentials of side-chain-side-chain interactions corresponding to pairs composed of charged and polar, polar and polar, charged and hydrophobic, and hydrophobic and hydrophobic side chains have been determined. A total of 144 four-dimensional potentials of mean force (PMFs) of all possible pairs of molecules modeling these pairs were determined by umbrella-sampling molecular dynamics simulations in explicit water as functions of distance and orientation, and the analytical expressions were then fitted to the PMFs. Depending on the type of interacting sites, the analytical approximation to the PMF is a sum of terms corresponding to van der Waals interactions and cavity-creation involving the nonpolar sections of the side chains and van der Waals, cavity-creation, and electrostatic (charge-dipole or dipole-dipole) interaction energies and polarization energies involving the charged or polar sections of the side chains. The model used in this work reproduces all features of the interacting pairs. The UNited RESidue force field with the new side-chain-side-chain interaction potentials was preliminarily tested with the N-terminal part of the B-domain of staphylococcal protein A (PDBL 1BDD ; a three-α-helix bundle) and UPF0291 protein YnzC from Bacillus subtilis (PDB: 2HEP ; an α-helical hairpin).

  9. Synthesis and DNA transfection properties of new head group modified malonic acid diamides.

    PubMed

    Wölk, Christian; Heinze, Martin; Kreideweiss, Patrick; Dittrich, Matthias; Brezesinski, Gerald; Langner, Andreas; Dobner, Bodo

    2011-05-16

    Malonic acid diamides with two long hydrophobic alkyl chains and a basic polar head group as a new class of non-viral gene transferring compounds have shown high transfection efficiency and moderate toxicity. Based on the results obtained with saturated and unsaturated alkyl residues new derivatives with a more complex head group structure have been synthesized. For this purpose, cationic respectively basic groups were introduced by one or two lysine residues bound via tris(aminoethyl)amine spacer to the malonic acid diamide backbone. By studying in vitro gene delivery an increase of transfection efficacy was observed when using lipids with at least one unsaturated alkyl chain. This leads to cationic lipids exhibiting comparable or even higher transfection efficacies compared to the commercially available transfection agents LipofectAmine™ and SuperFect™. Phase transitions and phase structures of selected compounds have been analyzed and discussed in terms of transfection abilities. Particle size and zeta potential of liposomes and lipoplexes were also determined.

  10. Mathematical Characterization of Protein Sequences Using Patterns as Chemical Group Combinations of Amino Acids

    PubMed Central

    Choudhury, Pabitra Pal; Jana, Siddhartha Sankar

    2016-01-01

    Comparison of amino acid sequence similarity is the fundamental concept behind the protein phylogenetic tree formation. By virtue of this method, we can explain the evolutionary relationships, but further explanations are not possible unless sequences are studied through the chemical nature of individual amino acids. Here we develop a new methodology to characterize the protein sequences on the basis of the chemical nature of the amino acids. We design various algorithms for studying the variation of chemical group transitions and various chemical group combinations as patterns in the protein sequences. The amino acid sequence of conventional myosin II head domain of 14 family members are taken to illustrate this new approach. We find two blocks of maximum length 6 aa as ‘FPKATD’ and ‘Y/FTNEKL’ without repeating the same chemical nature and one block of maximum length 20 aa with the repetition of chemical nature which are common among all 14 members. We also check commonality with another motor protein sub-family kinesin, KIF1A. Based on our analysis we find a common block of length 8 aa both in myosin II and KIF1A. This motif is located in the neck linker region which could be responsible for the generation of mechanical force, enabling us to find the unique blocks which remain chemically conserved across the family. We also validate our methodology with different protein families such as MYOI, Myosin light chain kinase (MLCK) and Rho-associated protein kinase (ROCK), Na+/K+-ATPase and Ca2+-ATPase. Altogether, our studies provide a new methodology for investigating the conserved amino acids’ pattern in different proteins. PMID:27930687

  11. [Preparation, characterization and adsorption performance of mesoporous activated carbon with acidic groups].

    PubMed

    Li, Kun-Quan; Li, Ye; Zheng, Zheng; Zhang, Yu-Xuan

    2013-06-01

    Mesoporous activated carbons containing acidic groups were prepared with cotton stalk based fiber as raw materials and H3PO4 as activating agent by one step carbonization method. Effects of impregnation ratio, carbonization temperature and heat preservation time on the yield, elemental composition, oxygen-containing acid functional groups and adsorptive capacity of activated carbon were studied. The adsorption capacity of the prepared activated carbon AC-01 for p-nitroaniline and Pb(II) was studied, and the adsorption mechanism was also suggested according to the equilibrium experimental results. The maximum yield of activated carbons prepared from cotton stalk fiber reached 35.5% when the maximum mesoporous volume and BET surface area were 1.39 cm3 x g(-1) and 1 731 m2 x g(-1), respectively. The activated carbon AC-01 prepared under a H3 PO4/precursor ratio of 3:2 and activated at 900 degrees C for 90 min had a total pore volume of 1.02 cm3 x g(-1), a micoporous ratio of 31%, and a mesoporous ratio of 65%. The pore diameter of the mesoporous activated carbon was mainly distributed in the range of 2-5 nm. The Langmuir maximum adsorption capacities of Pb(II) and p-nitroaniline on cotton stalk fiber activated carbon were 123 mg x g(-1) and 427 mg x g(-1), respectively, which were both higher than those for commercial activated carbon fiber ACF-CK. The equilibrium adsorption experimental data showed that mesopore and oxygen-containing acid functional groups played an important role in the adsorption.

  12. Alternatives to Nitric Acid Stripping in the Caustic-Side Solvent Extraction (CSSX) Process for Cesium Removal from Alkaline High-Level Waste

    SciTech Connect

    Delmau, Laetitia Helene; Haverlock, Tamara; Bazelaire, Eve; Bonnesen, Peter V; Ditto, Mary E; Moyer, Bruce A

    2009-01-01

    Effective alternatives to nitric acid stripping in the Caustic-Side Solvent Extraction (CSSX) solvent have been demonstrated in this work. The CSSX solvent employs calix[4]arene-bis(tert-octylbenzo-18-crown-6) (BOBCalixC6) as the cesium extractant in a modified alkane diluent for decontamination of alkaline high-level wastes. Results reported in this paper support the idea that replacement of the nitrate anion by a much more hydrophilic anion like borate can substantially lower cesium distribution ratios on stripping. Without any other change in the CSSX flowsheet, however, the use of a boric acid stripping solution in place of the 1 mM nitric acid solution used in the CSSX process marginally, though perhaps still usefully, improves stripping. The less-than-expected improvement was explained by the carryover of nitrate from scrubbing into stripping. Accordingly, more effective stripping is obtained after a scrub of the solvent with 0.1 M sodium hydroxide. Functional alternatives to boric acid include sodium bicarbonate or cesium hydroxide as strip solutions. Profound stripping improvement is achieved when trioctylamine, one of the components of the CSSX solvent, is replaced with a commercial guanidine reagent (LIX 79). The more basic guanidine affords greater latitude in selection of aqueous conditions in that it protonates even at mildly alkaline pH values. Under process-relevant conditions, cesium distributions on stripping are decreased on the order of 100-fold compared with current CSSX performance. The extraction properties of the solvent were preserved unchanged over three successive extract-scrub-strip cycles. From the point of view of compatibility with downstream processing, boric acid represents an attractive stripping agent, as it is also a potentially ideal feed for borosilicate vitrification of the separated 137Cs product stream. Possibilities for use of these results toward a dramatically better next-generation CSSX process, possibly one employing the

  13. Evaluation of colistin and nalidixic acid in Todd-Hewitt broth for selective isolation of group B streptocci.

    PubMed

    Fenton, L J; Harper, M H

    1979-02-01

    Todd-Hewitt broth (THB) containing colistin and nalidixic acid was compared with four other media with respect to efficacy of isolation of group B streptocci. It was effective as plain THB, THB with gentamicin and nalidixic acid and blood, and THB with colistin, nalidixic acid, and blood. THB with gentamicin and nalidixic acid, but without blood, was inhibitory to group B streptocci. The value of THB with colistin and nalidixic acid lies in its ability to successfully inhibit gram-negative organisms and still promote group B streptococcal growth without the addition of blood. This greatly reduces the time and expense of media preparation and permits early determination of bacterial growth, so that other means of rapidly identifying group B streptocci can be applied at the earliest possible time.

  14. Evaluation of colistin and nalidixic acid in Todd-Hewitt broth for selective isolation of group B streptocci.

    PubMed Central

    Fenton, L J; Harper, M H

    1979-01-01

    Todd-Hewitt broth (THB) containing colistin and nalidixic acid was compared with four other media with respect to efficacy of isolation of group B streptocci. It was effective as plain THB, THB with gentamicin and nalidixic acid and blood, and THB with colistin, nalidixic acid, and blood. THB with gentamicin and nalidixic acid, but without blood, was inhibitory to group B streptocci. The value of THB with colistin and nalidixic acid lies in its ability to successfully inhibit gram-negative organisms and still promote group B streptococcal growth without the addition of blood. This greatly reduces the time and expense of media preparation and permits early determination of bacterial growth, so that other means of rapidly identifying group B streptocci can be applied at the earliest possible time. PMID:372220

  15. Synthesis and physicochemical properties of polysiloxane functionalized with aminoacetic acid groups

    NASA Astrophysics Data System (ADS)

    Lakiza, N. V.; Neudachina, L. K.

    2016-07-01

    Polysiloxane functionalized with aminoacetic acid groups was synthesized using sol-gel technology. Elemental analysis and FTIR spectroscopy were used to determine the composition of the polysiloxane show that it is a mesoporous material with a developed surface (109.4 m2/g). It was found that the selective properties of carboxymethylated polysiloxane towards transition metal ions simultaneously present in an ammonium acetate solution change in the order Zn < Cu > Ni > Co > Pb > Cd. It was shown that the sorption of copper(II) ions by carboxymethylated aminopropylpolysiloxane with particle sizes of 50-71 μm reaches its maximum level within 2 h; the rate-limiting step of the process is the chemical reaction between the ions and the polysiloxane functional groups; and the pseudo-second-order model is the best way of describing sorption.

  16. THz and mid-IR spectroscopy of interstellar ice analogs: methyl and carboxylic acid groups.

    PubMed

    Ioppolo, S; McGuire, B A; Allodi, M A; Blake, G A

    2014-01-01

    A fundamental problem in astrochemistry concerns the synthesis and survival of complex organic molecules (COMs) throughout the process of star and planet formation. While it is generally accepted that most complex molecules and prebiotic species form in the solid phase on icy grain particles, a complete understanding of the formation pathways is still largely lacking. To take full advantage of the enormous number of available THz observations (e.g., Herschel Space Observatory, SOFIA, and ALMA), laboratory analogs must be studied systematically. Here, we present the THz (0.3-7.5 THz; 10-250 cm(-1)) and mid-IR (400-4000 cm(-1)) spectra of astrophysically-relevant species that share the same functional groups, including formic acid (HCOOH) and acetic acid (CH3COOH), and acetaldehyde (CH3CHO) and acetone ((CH3)2CO), compared to more abundant interstellar molecules such as water (H2O), methanol (CH3OH), and carbon monoxide (CO). A suite of pure and mixed binary ices are discussed. The effects on the spectra due to the composition and the structure of the ice at different temperatures are shown. Our results demonstrate that THz spectra are sensitive to reversible and irreversible transformations within the ice caused by thermal processing, suggesting that THz spectra can be used to study the composition, structure, and thermal history of interstellar ices. Moreover, the THz spectrum of an individual species depends on the functional group(s) within that molecule. Thus, future THz studies of different functional groups will help in characterizing the chemistry and physics of the interstellar medium (ISM).

  17. Randomized, parallel-group, double-blind, controlled study to evaluate the efficacy and safety of carbohydrate-derived fulvic acid in topical treatment of eczema

    PubMed Central

    Gandy, Justin J; Snyman, Jacques R; van Rensburg, Constance EJ

    2011-01-01

    Background The purpose of this study was to evaluate the efficacy and safety of carbohydratederived fulvic acid (CHD-FA) in the treatment of eczema in patients two years and older. Methods In this single-center, double-blind, placebo-controlled, parallel-group comparative study, 36 volunteers with predetermined eczema were randomly assigned to receive either the study drug or placebo twice daily for four weeks. Results All safety parameters remained within normal limits, with no significant differences in either group. Significant differences were observed for both severity and erythema in the placebo and CHD-FA treated groups, and a significant difference was observed for scaling in the placebo-treated group. With regard to the investigator assessment of global response to treatment, a significant improvement was observed in the CHD-FA group when compared with the placebo group. A statistically significant decrease in visual analog scale score was observed in both groups, when comparing the baseline with the final results. Conclusion CHD-FA was well tolerated, with no difference in reported side effects other than a short-lived burning sensation on application. CHD-FA significantly improved some aspects of eczema. Investigator assessment of global response to treatment with CHD-FA was significantly better than that with emollient therapy alone. The results of this small exploratory study suggest that CHD-FA warrants further investigation in the treatment of eczema. PMID:21931500

  18. The difluoromethylene (CF2) group in aliphatic chains: Synthesis and conformational preference of palmitic acids and nonadecane containing CF2 groups.

    PubMed

    Wang, Yi; Callejo, Ricardo; Slawin, Alexandra M Z; O'Hagan, David

    2014-01-06

    The syntheses of palmitic acids and a nonadecane are reported with CF2 groups located 1,3 or 1,4 to each other along the aliphatic chain. Specifically 8,8,10,10- and 8,8,11,11-tetrafluorohexadecanoic acids (6b and 6c) are prepared as well as the singly modified analogue 8,8-difluorohexadecanoic acid (6a). Also 8,8,11,11-tetrafluorononadecane (27) is prepared as a pure hydrocarbon containing a 1,4-di-CF2 motif. The modified palmitic acids are characterized by differential scanning calorimetry (DSC) to determine melting points and phase behaviour relative to palmitic acid (62.5 °C). It emerges that 6c, with the CF2 groups placed 1,4- to each other, has a significantly higher melting point (89.9 °C) when compared to the other analogues and palmitic acid itself. It is a crystalline compound and the structure reveals an extended anti-zig-zag chain. Similarly 8,8,11,11-tetrafluorononadecane (27) adopts an extended anti-zig-zag structure. This is rationalized by dipolar relaxation between the two CF2 groups placed 1,4 to each other in the extended anti-zig-zag chain and suggests a design modification for long chain aliphatics which can introduce conformational stability.

  19. Protodeboronation of ortho- and para-phenol boronic acids and application to ortho and meta functionalization of phenols using boronic acids as blocking and directing groups.

    PubMed

    Lee, Chun-Young; Ahn, Su-Jin; Cheon, Cheol-Hong

    2013-12-06

    The first metal-free thermal protodeboronation of ortho- and para-phenol boronic acids in DMSO was developed. The protodeboronation was successfully applied to the synthesis of ortho- and meta-functionalized phenols using the boronic acid moiety as a blocking group and a directing group, respectively. Mechanistic studies suggested that this protodeboronation proceeds through the coordination of water to the boron atom followed by σ-bond metathesis.

  20. Strategy to improve photovoltaic performance of DSSC sensitized by zinc prophyrin using salicylic acid as a tridentate anchoring group.

    PubMed

    Gou, Faliang; Jiang, Xu; Fang, Ran; Jing, Huanwang; Zhu, Zhenping

    2014-05-14

    Three new zinc porphyrin dyes attached to ethynyl benzoic acid as an electron transmission and anchoring group have been designed, synthesized, and well-characterized. The performances of their sensitized solar cells have been investigated by optical, photovoltaic, and electrochemical methods. The photoelectric conversion efficiency of the solar cells sensitized by the dye with salicylic acid as an anchoring group demonstrated obvious enhancement when compared with that sensitized by the dye with carboxylic acid as an anchoring group. The density functional theory calculations and the electrochemical impedance spectroscopies revealed that tridentate binding modes could increase the efficiency of electron injection from dyes to the TiO2 nanoparticles by more electron pathways.

  1. Intrinsic Amino Acid Side-Chain Hydrophilicity/Hydrophobicity Coefficients Determined by Reversed-Phase High-Performance Liquid Chromatography of Model Peptides: Comparison with Other Hydrophilicity/Hydrophobicity Scales

    PubMed Central

    Mant, Colin T.; Kovacs, James M.; Kim, Hyun-Min; Pollock, David D.; Hodges, Robert S.

    2009-01-01

    An accurate determination of the intrinsic hydrophilicity/hydrophobicity of amino acid side-chains in peptides and proteins is fundamental in understanding many areas, including protein folding and stability, peptide and protein function, protein-protein interactions and peptide/protein oligomerization, as well as the design of protocols for purification and characterization of peptides and proteins. Our definition of intrinsic hydrophilicity/hydrophobicity of side-chains is the maximum possible hydrophilicity/hydrophobicity of side-chains in the absence of any nearest-neighbor effects and/or any conformational effects of the polypeptide chain that prevent full expression of side-chain hydrophilicity/hydrophobicity. In this review, we have compared an experimentally-derived intrinsic side-chain hydrophilicity/hydrophobicity scale generated from RP-HPLC retention behavior of de novo designed synthetic model peptides at pH 2 and pH 7 with other RP-HPLC-derived scales, as well as scales generated from classic experimental and calculation-based methods of octanol/water partitioning of Nα-acetyl-amino-acid amides or free energy of transfer of free amino acids. Generally poor correlation was found with previous RP-HPLC-derived scales, likely due to the random nature of the peptide mixtures in terms of varying peptide size, conformation and frequency of particular amino acids. In addition, generally poor correlation with the classical approaches served to underline the importance of the presence of a polypeptide backbone when generating intrinsic values. We have shown that the intrinsic scale determined here is in full agreement with the structural characteristics of amino acid side-chains. PMID:19795449

  2. Are carboxyl groups the most acidic sites in amino acids? Gas-phase acidities, photoelectron spectra, and computations on tyrosine, p-hydroxybenzoic acid, and their conjugate bases.

    PubMed

    Tian, Zhixin; Wang, Xue-Bin; Wang, Lai-Sheng; Kass, Steven R

    2009-01-28

    Deprotonation of tyrosine in the gas phase was found to occur preferentially at the phenolic site, and the conjugate base consists of a 70:30 mixture of phenoxide and carboxylate anions at equilibrium. This result was established by developing a chemical probe for differentiating these two isomers, and the presence of both ions was confirmed by photoelectron spectroscopy. Equilibrium acidity measurements on tyrosine indicated that deltaG(acid)(o) = 332.5 +/- 1.5 kcal mol(-1) and deltaH(acid)(o) = 340.7 +/- 1.5 kcal mol(-1). Photoelectron spectra yielded adiabatic electron detachment energies of 2.70 +/- 0.05 and 3.55 +/- 0.10 eV for the phenoxide and carboxylate anions, respectively. The H/D exchange behavior of deprotonated tyrosine was examined using three different alcohols (CF3CH2OD, C6H5CH2OD, and CH3CH2OD), and incorporation of up to three deuterium atoms was observed. Two pathways are proposed to account for these results, and all of the experimental findings are supplemented with B3LYP/aug-cc-pVDZ and G3B3 calculations. In addition, it was found that electrospray ionization of tyrosine from a 3:1 (v/v) CH3OH/H2O solution using a commercial source produces a deprotonated [M-H]- anion with the gas-phase equilibrium composition rather than the structure of the ion that exists in aqueous media. Electrospray ionization from acetonitrile, however, leads largely to the liquid-phase (carboxylate) structure. A control molecule, p-hydroxybenzoic acid, was found to behave in a similar manner. Thus, the electrospray conditions that are employed for the analysis of a compound can alter the isomeric composition of the resulting anion.

  3. Non-pore lining amino acid side chains influence anion selectivity of the human CFTR Cl− channel expressed in mammalian cell lines

    PubMed Central

    Linsdell, Paul; Zheng, Shu-Xian; Hanrahan, John W

    1998-01-01

    The effects of individually mutating two adjacent threonine residues in the sixth membrane-spanning region (TM6) of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel on permeation properties were examined using patch clamp recording from mammalian cell lines stably expressing human CFTR.A number of mutations of T338 significantly affected the permeation properties of the channel. Increases and decreases in single channel conductance were observed for different mutants. Anion selectivity was strongly affected, with no two channel variants sharing the same selectivity sequence. Several mutations led to strong inward rectification of the macroscopic current-voltage relationship. The effects of these mutations on permeation properties were correlated with the size of the amino acid side chain substituted, rather than its chemical nature.Most mutations of T339 resulted in a lack of functional channel expression and apparent misprocessing of the protein. One mutant, T339V, was characterized in detail; its permeation properties were significantly altered, although these effects were not as strong as for T338 mutations.These results suggest an important role for T338 in controlling the permeation properties of the CFTR Cl− channel. It is suggested that mutation of this residue alters the interaction between permeating anions and the channel pore via an indirect effect on the orientation of the TM6 helix. PMID:9729613

  4. [Amino acid and peptide derivatives of the tylosin family of macrolide antibiotics modified at the aldehyde group].

    PubMed

    Sumbatian, N V; Kuznetsova, I V; Karpenko, V V; Fedorova, N V; Chertkov, V A; Korshunova, G A; Bogdanov, A A

    2010-01-01

    Fourteen new functionally active amino acid and peptide derivatives of the antibiotics tylosin, desmycosin, and 5-O-mycaminosyltylonolide were synthesized in order to study the interaction of the growing polypeptide chain with the ribosomal tunnel. The conjugation of various amino acids and peptides with a macrolide aldehyde group was carried out by two methods: direct reductive amination with the isolation of the intermediate Schiff bases or through binding via oxime using the preliminarily obtained derivatives of 2-aminooxyacetic acid.

  5. Bimane: A Visible Light Induced Fluorescent Photoremovable Protecting Group for the Single and Dual Release of Carboxylic and Amino Acids.

    PubMed

    Chaudhuri, Amrita; Venkatesh, Yarra; Behara, Krishna Kalyani; Singh, N D Pradeep

    2017-03-10

    A series of ester conjugates of carboxylic and amino acids were synthesized based on bimane fluorescent photoremovable protecting group (FPRPG). The photorelease of single and dual (same as well as different) carboxylic and amino acids is demonstrated from a single bimane molecule on irradiation with visible light (λ ≥ 410 nm). The detailed mechanistic study of photorelease revealed that the release of two caged acids is simultaneous but in a stepwise pathway.

  6. Click with a boronic acid handle: a neighboring group-assisted click reaction that allows ready secondary functionalization.

    PubMed

    Draganov, Alexander B; Wang, Ke; Holmes, Jalisa; Damera, Krishna; Wang, Danzhu; Dai, Chaofeng; Wang, Binghe

    2015-10-21

    The feasibility of a neighboring boronic acid-facilitated facile condensation of an aldehyde is described. This reaction is bio-orthogonal, complete at room temperature within minutes, and suitable for bioconjugation chemistry. The boronic acid group serves the dual purpose of catalyzing the condensation reaction and being a handle for secondary functionalization.

  7. Intrinsic acidity of aluminum, chromium (III) and iron (III) μ 3-hydroxo functional groups from ab initio electronic structure calculations

    NASA Astrophysics Data System (ADS)

    Rustad, James R.; Dixon, David A.; Felmy, Andrew R.

    2000-05-01

    Density functional calculations are performed on M 3(OH) 7(H 2O) 62+ and M 3O(OH) 6(H 2O) 6+ clusters for MAl, Cr(III), and Fe(III), allowing determination of the relative acidities of the μ 3-hydroxo and aquo functional groups. Contrary to previous predictions and rationalizations, Fe 3OH and Al 3OH groups have nearly the same intrinsic acidity, while Cr 3OH groups are significantly more acidic. The gas-phase acidity of the Fe 3OH site is in good agreement with the value predicted by the molecular mechanics model previously used to estimate the relative acidities of surface sites on iron oxides. [ J. R. Rustad et al. (1996)Geochim. Cosmochim. Acta 60, 1563]. Acidities of aquo functional groups were also computed for Al and Cr. The AlOH 2 site is more acidic than the Al 3OH site, whereas the Cr 3OH site is more acidic than the CrOH 2 site. These findings predict that the surface charging behavior of chromium oxides/oxyhydroxides should be distinguishable from their Fe, Al counterparts. The calculations also provide insight into why the lepidocrocite/boehmite polymorph is not observed for CrOOH.

  8. Evaluation of the cyclopentane-1,2-dione as a potential bio-isostere of the carboxylic acid functional group.

    PubMed

    Ballatore, Carlo; Gay, Bryant; Huang, Longchuan; Robinson, Katie Herbst; James, Michael J; Trojanowski, John Q; Lee, Virginia M-Y; Brunden, Kurt R; Smith, Amos B

    2014-09-01

    Cycloalkylpolyones hold promise in drug design as carboxylic acid bio-isosteres. To investigate cyclopentane-1,2-diones as potential surrogates of the carboxylic acid functional group, the acidity, tautomerism, and geometry of hydrogen bonding of representative compounds were evaluated. Prototypic derivatives of the known thromboxane A2 prostanoid (TP) receptor antagonist, 3-(3-(2-((4-chlorophenyl)sulfonamido)-ethyl)phenyl)propanoic acid, in which the carboxylic acid moiety is replaced by the cyclopentane-1,2-dione unit, were synthesized and evaluated as TP receptor antagonists. Cyclopentane-1,2-dione derivative 9 was found to be a potent TP receptor antagonist with an IC50 value comparable to that of the parent carboxylic acid. These results indicate that the cyclopentane-1,2-dione may be a potentially useful carboxylic acid bio-isostere.

  9. A simple colorimetric chemosensor bearing a carboxylic acid group with high selectivity for CN-

    NASA Astrophysics Data System (ADS)

    Park, Gyeong Jin; Choi, Ye Won; Lee, Dongkuk; Kim, Cheal

    2014-11-01

    A new simple ‘naked eye' chemosensor 1 (sodium (E)-2-((2-(3-hydroxy-2-naphthoyl)hydrazono)methyl)benzoate) has been synthesized for detection of CN- in a mixture of DMF/H2O (9:1). The sensor 1 comprises of a naphthoic hydrazide as efficient hydrogen bonding donor group and a benzoic acid as the moiety with the water solubility. The receptor 1 showed high selectivity toward cyanide ions in a 1:1 stoichiometric manner, which induces a fast color change from colorless to yellow for CN- over other anions. Therefore, receptor 1 could be useful for cyanide detection in aqueous environment, displaying a high distinguishable selectivity from hydrogen bonded anions and being clearly visible to the naked eye.

  10. Type II phosphoinositide 5-phosphatases have unique sensitivities towards fatty acid composition and head group phosphorylation.

    PubMed

    Schmid, Annette C; Wise, Helen M; Mitchell, Christina A; Nussbaum, Robert; Woscholski, Rüdiger

    2004-10-08

    The catalytic properties of the type II phosphoinositide 5-phosphatases of Lowe's oculocerebrorenal syndrome, INPP5B, Synaptojanin1, Synaptojanin2 and SKIP were analysed with respect to their substrate specificity and enzymological properties. Our data reveal that all phosphatases have unique substrate specificities as judged by their corresponding KM and VMax values. They also possessed an exclusive sensitivity towards fatty acid composition, head group phosphorylation and micellar presentation. Thus, the biological function of these enzymes will not just be determined by their corresponding regulatory domains, but will be distinctly influenced by their catalytic properties as well. This suggests that the phosphatase domains fulfil a unique catalytic function that cannot be fully compensated by other phosphatases.

  11. Amino Acid Derivatives as New Zinc Binding Groups for the Design of Selective Matrix Metalloproteinase Inhibitors

    PubMed Central

    Giustiniano, Mariateresa; Agamennone, Mariangela; Rossello, Armando; Gomez-Monterrey, Isabel; Novellino, Ettore; Campiglia, Pietro; Vernieri, Ermelinda; Bertamino, Alessia; Carotenuto, Alfonso

    2013-01-01

    A number of matrix metalloproteinases (MMPs) are important medicinal targets for conditions ranging from rheumatoid arthritis to cardiomyopathy, periodontal disease, liver cirrhosis, multiple sclerosis, and cancer invasion and metastasis, where they showed to have a dual role, inhibiting or promoting important processes involved in the pathology. MMPs contain a zinc (II) ion in the protein active site. Small-molecule inhibitors of these metalloproteins are designed to bind directly to the active site metal ions. In an effort to devise new approaches to selective inhibitors, in this paper, we describe the synthesis and preliminary biological evaluation of amino acid derivatives as new zinc binding groups (ZBGs). The incorporation of selected metal-binding functions in more complex biphenyl sulfonamide moieties allowed the identification of one compound able to interact selectively with different MMP enzymatic isoforms. PMID:23555050

  12. Copoly(arlene ether)s containing pendant sulfonic acid groups as proton exchange membrane

    SciTech Connect

    Kim, Yu Seung; Kim, Dae Sik; Robertson, Gilles; Guiver, Michael

    2008-01-01

    A copoly(arylene ether) (PAE) with high fluorine content and a copoly(arylene ether nitrile) (PAEN) with high nitrile content, each containing pendant phenyl sulfonic acids were synthesized. The P AE and PAEN were prepared from decafluorobiphenyl (DFBP) and difluorobenzonitrile (DFBN) respectively, by polycondensation with 2-phenylhydroquinone (PHQ) by conventional aromatic nucleophilic substitution reactions. The sulfonic acid groups were introduced by mild post-sulfonation exclusively on the para-position of the pendant phenyl ring in PHQ. The membrane properties of the resulting sulfonated copolymers sP AE and sP AEN were compared for fuel cell applications. The copolymers sPAE and sPAEN, each having a degree of sulfonation (DS) of 1.0 had high ion exchange capacities (IEC{sub v}(wet) (volume-based, wet state)) of 1.77 and 2.55 meq./cm{sup 3}, high proton conductivities of 135.4 and 140.1 mS/cm at 80 C, and acceptable volume-based water uptake of 44.5-51.9 vol% at 80 C, respectively, compared to Nafion. The data points of these copolymer membranes are located in the area of outstanding properties in the trade-off plot of alternative hydrocarbon polyelectrolyte membranes (PEM) for the relationship between proton conductivity versus water uptake (weight based or volume based). Furthermore, the relative selectivity derived from proton conductivity and methanol permeability is higher than that of Nafion.

  13. Amino acid ester prodrugs conjugated to the α-carboxylic acid group do not display affinity for the L-type amino acid transporter 1 (LAT1).

    PubMed

    Rautio, Jarkko; Kärkkäinen, Jussi; Huttunen, Kristiina M; Gynther, Mikko

    2015-01-23

    L-type amino acid transporter (LAT1) is an intriguing target for carrier-mediated transport of drugs as it is highly expressed in the blood-brain barrier and also in various types of cancer. Several studies have proposed that in order for compounds to act as LAT1 substrates they should possess both negatively charged α-carboxyl and positively charged α-amino groups. However, in some reports, such as in two recent publications describing an isoleucine-quinidine ester prodrug (1), compounds having no free α-carboxyl group have been reported to exhibit high affinity for LAT1 in vitro. In the present study, 1 was synthesized and its affinity for LAT1 was evaluated both with an in situ rat brain perfusion technique and in the human breast cancer cell line MCF-7 in vitro. 1 showed no affinity for LAT1 in either model nor did it show any affinity for LAT2 in an in vitro study. Our results confirm the earlier reported requirements for LAT1 substrates. Thus drugs or prodrugs with substituted α-carboxyl group cannot bind to LAT with high affinity.

  14. THE SMALL ACID SOLUBLE PROTEINS (SASP α and SASP β) OF BACILLUS WEIHENSTEPHANENSIS AND B. MYCOIDES GROUP 2 ARE THE MOST DISTINCT AMONG THE B. CEREUS GROUP

    PubMed Central

    Callahan, Courtney; Fox, Karen; Fox, Alvin

    2009-01-01

    The Bacillus cereus group includes Bacillus anthracis, Bacillus cereus, Bacillus thuringiensis, Bacillus mycoides and Bacillus weihenstephanensis. The small acid-soluble spore protein (SASP) β has been previously demonstrated to be among the biomarkers differentiating B. anthracis and B. cereus; SASP β of B. cereus most commonly exhibits one or two amino acid substitutions when compared to B. anthracis. SASP α is conserved in sequence among these two species. Neither SASP α nor β for B. thuringiensis, B. mycoides and B. weihenstephanensis have been previously characterized as taxonomic discriminators. In the current work molecular weight (MW) variation of these SASPs were determined by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) for representative strains of the 5 species within the B. cereus group. The measured MWs also correlate with calculated MWs of translated amino acid sequences generated from whole genome sequencing projects. SASP α and β demonstrated consistent MW among B. cereus, B. thuringiensis, and B. mycoides strains (group 1). However B. mycoides (group 2) and B. weihenstephanensis SASP α and β were quite distinct making them unique among the B. cereus group. Limited sequence changes were observed in SASP α (at most 3 substitutions and 2 deletions) indicating it is a more conserved protein than SASP β (up to 6 substitutions and a deletion). Another even more conserved SASP, SASP α-β type, was described here for the first time. PMID:19616612

  15. Synthesis and luminescence properties of polymeric complexes of Cu(II), Zn(II) and Al(III) with 8-hydroxyquinoline side group-containing polystyrene

    NASA Astrophysics Data System (ADS)

    Gao, Baojiao; Wei, Xiaopeng; Zhang, Yanyan

    2013-01-01

    Three kinds of metalloquinolate-containing polystyrene were prepared via a polymer reaction and a coordination reaction. 5-Chloromethyl-8-hydroxyquinoline (CHQ) was first prepared through the chloromethylation reaction of 8-hydroxyquinoline (HQ) with 1,4-bichloromethoxy-butane as chloromethylation reagent. A polymer reaction, Friedel-Crafts alkylation reaction, was carried out between polystyrene (PS) and CHQ in the presence of Lewis catalyst, and HQ was bonded onto the side chains of PS, obtaining 8-hydroxyquinoline-functionalized Polystyrene, HQ-PS. And then, by using one-pot method with two-stage procedures, the coordination reaction of HQ-PS and small molecule HQ with metal ions including Al(III), Zn(II) and Cu(II) ions, was allowed to be carried out, and three polymeric metalloquinolates, AlQ3-PS, ZnQ2-PS and CuQ2-PS, were successfully prepared, respectively. In the chemical structures of these polymeric metalloquinolates, metalloquinolates were chemically attached onto the side chains of PS. HQ-PS and three polymeric metalloquinolates were fully characterized by FTIR, 1H NMR and TGA. The luminescence properties of the three polymeric metalloquinolates were mainly investigated by UV/Vis absorption spectra and fluorescence emission spectra in solutions and in solid film states. When excited by the ray at about 365 nm, the three polymeric metalloquinolates have blue-green luminescence, and the main emission peaks in the DMF solutions are located at 490, 482 and 502 nm for AlQ3-PS, ZnQ2-PS and CuQ2-PS, respectively. As compared with their emissions in solutions, the emissions in solid film states are red-shifted to some extent, and the main emission peaks are located at 500, 488 and 510 nm for AlQ3-PS, ZnQ2-PS and CuQ2-PS, respectively. Besides, these polymeric metalloquinolates have higher thermal stability than PS as polymeric skeleton.

  16. Acidity enhancement of unsaturated bases of group 15 by association with borane and beryllium dihydride. Unexpected boron and beryllium Brønsted acids.

    PubMed

    Martín-Sómer, Ana; Mó, Otilia; Yáñez, Manuel; Guillemin, Jean-Claude

    2015-01-21

    The intrinsic acidity of CH2[double bond, length as m-dash]CHXH2, HC[triple bond, length as m-dash]CXH2 (X = N, P, As, Sb) derivatives and of their complexes with BeH2 and BH3 has been investigated by means of high-level density functional theory and molecular orbital ab initio calculations, using as a reference the ethyl saturated analogues. The acidity of the free systems steadily increases down the group for the three series of derivatives, ethyl, vinyl and ethynyl. The association with both beryllium dihydride and borane leads to a very significant acidity enhancement, being larger for BeH2 than for BH3 complexes. This acidity enhancement, for the unsaturated compounds, is accompanied by a change in the acidity trends down the group, which do not steadily decrease but present a minimum value for both the vinyl- and the ethynyl-phosphine. When the molecule acting as the Lewis acid is beryllium dihydride, the π-type complexes in which the BeH2 molecules interact with the double or triple bond are found, in some cases, to be more stable, in terms of free energies, than the conventional complexes in which the attachment takes place at the heteroatom, X. The most important finding, however, is that P, As, and Sb ethynyl complexes with BeH2 do not behave as P, As, or Sb Brønsted acids, but unexpectedly as Be acids.

  17. Electro-oxidation of methanol in sulfuric acid electrolyte on platinized-carbon electrodes with several functional-group characteristics

    SciTech Connect

    Shukla, A.K.; Ravikumar, M.K.; Roy, A.; Barman, S.R.; Sarma, D.D. . Solid State and Structural Chemistry Unit)

    1994-06-01

    The effect of acid/base functional-groups associated with platinized-carbon electrodes on their catalytic activity toward electro-oxidation of methanol in sulfuric acid electrolyte at 60 C is studied. Platinized-carbon electrodes with small amounts of functional groups exhibit higher catalytic activity compared to those with large concentration of acidic/basic surface functionalities. The overpotential for methanol oxidation is minimum on electrodes of platinized carbons with pHzpc values between 6 and 7. An X-ray photoelectron spectroscopic study of various platinized carbons suggests that the acid/base surface function-groups produce ample amounts of surface Pt-oxides and a consequent decrease in activity toward methanol oxidation.

  18. Molecular glass positive i-line photoresist materials containing 2,1,4-DNQ and acid labile group

    NASA Astrophysics Data System (ADS)

    Wang, Liyuan; Yu, Jinxing; Xu, Na

    2010-04-01

    Recent years increasing attention has been given to molecular glass resist materials. In this paper, maleopimaric acid, cycloaddition reaction product of rosin with maleic anhydride, was reacted with hydroxylamine and then further esterified with 2-diazo-1-naphthoquinone-4-sulfonyl chloride to give N-hydroxy maleopimarimide sulfonate. The carboxylic acid group of the compound was then protected by the reaction of this compound with vinyl ethyl ether or dihydropyran. Thus obtained compounds were amorphous. When irradiated with i-line light, the 2,1,4-DNQ group undergo photolysis not only to give off nitrogen gas but also generate sulfonic acid which can result in the decomposition of the acid labile group. So, a novel chemically amplified positive i-line molecular glass photoresists can be formed by the compound and other acidolytic molecular glass compounds. The lithographic performance of the resist materials is evaluated.

  19. Evidence for a Morin Type Intramolecular Cyclization of an Alkene with a Phenylsulfenic Acid Group in Neutral Aqueous Solution

    PubMed Central

    Keerthi, Kripa; Sivaramakrishnan, Santhosh; Gates, Kent S.

    2009-01-01

    Sulfenic acids (RSOH) are among the most common sulfur-centered reactive intermediates generated in biological systems. Given the biological occurrence of sulfenic acids, it is important to explore the reactivity of these intermediates under physiological conditions. The Morin rearrangement is a synthetic process developed for the conversion of penicillin derivatives into cephalosporins that proceeds via nucleophilic attack of an alkene on a sulfenic acid intermediate. In its classic form, the Morin reaction involves initial elimination of a sulfenic acid from a cyclic sulfoxide, followed by intramolecular cyclization of the resulting alkene and sulfenic acid groups to generate an episulfonium ion intermediate that undergoes further reaction to yield ring-expanded products. On the basis of the existing literature, it is difficult to assess whether the reaction between an alkene and a sulfenic group can occur under mild conditions because the conditions required to generate the sulfenic acid from the sulfoxide precursor in the Morin reaction typically involve high temperatures and strong acid. In the work described here, β-sulfinylketone precursors were used to generate a “Morin type” sulfenic acid intermediate under mild conditions. This approach made it possible to demonstrate that the intramolecular cyclization of an alkene with a phenylsulfenic acid to generate an episulfonium ion intermediate can occur in neutral aqueous solution at room temperature. PMID:18500784

  20. Intermediate temperature proton conductors for PEM fuel cells based on phosphonic acid as protogenic group: a progress report.

    PubMed

    Steininger, H; Schuster, M; Kreuer, K D; Kaltbeitzel, A; Bingöl, B; Meyer, W H; Schauff, S; Brunklaus, G; Maier, J; Spiess, H W

    2007-04-21

    The melting behaviour and transport properties of straight chain alkanes mono- and difunctionalized with phosphonic acid groups have been investigated as a function of their length. The increase of melting temperature and decrease of proton conductivity with increasing chain length is suggested to be the consequence of an increasing ordering of the alkane segments which constrains the free aggregation of the phosphonic acid groups. However, the proton mobility is reduced to a greater extent than the proton diffusion coefficient indicating an increasing cooperativity of proton transport with increasing length of the alkane segment. The results clearly indicate that the "spacer concept", which had been proven successful in the optimization of the proton conductivity of heterocycle based systems, fails in the case of phosphonic acid functionalized polymers. Instead, a very high concentration of phosphonic acid functional groups forming "bulky" hydrogen bonded aggregates is suggested to be essential for obtaining very high proton conductivity. Aggregation is also suggested to reduce condensation reactions generally observed in phosphonic acid containing systems. On the basis of this understanding, the proton conductivities of poly(vinyl phosphonic acid) and poly(meta-phenylene phosphonic acid) are discussed. Though both polymers exhibit a substantial concentration of phosphonic acid groups, aggregation seems to be constrained to such an extent that intrinsic proton conductivity is limited to values below sigma = 10(-3) S cm(-1) at T = 150 degrees C. The results suggest that different immobilization concepts have to be developed in order to minimize the conductivity reduction compared to the very high intrinsic proton conductivity of neat phosphonic acid under quasi dry conditions. In the presence of high water activities, however, (as usually present in PEM fuel cells) the very high ion exchange capacities (IEC) possible for phosphonic acid functionalized ionomers (IEC

  1. Optimal conjugation of catechol group onto hyaluronic acid in coronary stent substrate coating for the prevention of restenosis

    PubMed Central

    Lih, Eugene; Choi, Seul Gi; Ahn, Dong June; Joung, Yoon Ki; Han, Dong Keun

    2016-01-01

    Although endovascular stenting has been used as an interventional therapy to treat cardio- and cerebro-vascular diseases, it is associated with recurrent vascular diseases following stent thrombosis and in-stent restenosis. In this study, a metallic stent was coated with dopamine-conjugated hyaluronic acid with different ratios of catechol group to improve hemocompatibility and re-endothelialization. Especially, we were interested in how much amount of catechol group is appropriate for the above-mentioned purposes. Therefore, a series of dopamine-conjugated hyaluronic acid conjugates with different ratios of catechol group were synthesized via a carbodiimide coupling reaction. Dopamine-conjugated hyaluronic acid conjugates were characterized with 1H-nuclear magnetic resonance and Fourier transform infrared spectroscopy, and the amount of catechol group in dopamine-conjugated hyaluronic acid was measured by ultraviolet spectrometer. Co-Cr substrates were polished and coated with various dopamine-conjugated hyaluronic acid conjugates under pH 8.5. Dopamine-conjugated hyaluronic acid amounts on the substrate were quantified by micro-bicinchoninic acid assay. Surface characteristics of dopamine-conjugated hyaluronic-acid-coated Co-Cr were evaluated by water contact angle, scanning electron microscopy, and atomic force microscopy. The hemocompatibility of the surface-modified substrates was assessed by protein adsorption and platelet adhesion tests. Adhesion and activation of platelets were confirmed with scanning electron microscopy and lactate dehydrogenase assay. Human umbilical vein endothelial cells were cultured on the substrates, and the viability, adhesion, and proliferation were investigated through cell counting kit-8 assay and fluorescent images. Obtained results demonstrated that optimal amounts of catechol group (100 µmol) in the dopamine-conjugated hyaluronic acid existed in terms of various properties such as hemocompatibility and cellular responses

  2. Optimal conjugation of catechol group onto hyaluronic acid in coronary stent substrate coating for the prevention of restenosis.

    PubMed

    Lih, Eugene; Choi, Seul Gi; Ahn, Dong June; Joung, Yoon Ki; Han, Dong Keun

    2016-01-01

    Although endovascular stenting has been used as an interventional therapy to treat cardio- and cerebro-vascular diseases, it is associated with recurrent vascular diseases following stent thrombosis and in-stent restenosis. In this study, a metallic stent was coated with dopamine-conjugated hyaluronic acid with different ratios of catechol group to improve hemocompatibility and re-endothelialization. Especially, we were interested in how much amount of catechol group is appropriate for the above-mentioned purposes. Therefore, a series of dopamine-conjugated hyaluronic acid conjugates with different ratios of catechol group were synthesized via a carbodiimide coupling reaction. Dopamine-conjugated hyaluronic acid conjugates were characterized with (1)H-nuclear magnetic resonance and Fourier transform infrared spectroscopy, and the amount of catechol group in dopamine-conjugated hyaluronic acid was measured by ultraviolet spectrometer. Co-Cr substrates were polished and coated with various dopamine-conjugated hyaluronic acid conjugates under pH 8.5. Dopamine-conjugated hyaluronic acid amounts on the substrate were quantified by micro-bicinchoninic acid assay. Surface characteristics of dopamine-conjugated hyaluronic-acid-coated Co-Cr were evaluated by water contact angle, scanning electron microscopy, and atomic force microscopy. The hemocompatibility of the surface-modified substrates was assessed by protein adsorption and platelet adhesion tests. Adhesion and activation of platelets were confirmed with scanning electron microscopy and lactate dehydrogenase assay. Human umbilical vein endothelial cells were cultured on the substrates, and the viability, adhesion, and proliferation were investigated through cell counting kit-8 assay and fluorescent images. Obtained results demonstrated that optimal amounts of catechol group (100 µmol) in the dopamine-conjugated hyaluronic acid existed in terms of various properties such as hemocompatibility and cellular responses.

  3. On the Other Side of the Fence: Effects of Social Categorization and Spatial Grouping on Memory and Attention for Own-Race and Other-Race Faces

    PubMed Central

    Kloth, Nadine; Shields, Susannah E.; Rhodes, Gillian

    2014-01-01

    The term “own-race bias” refers to the phenomenon that humans are typically better at recognizing faces from their own than a different race. The perceptual expertise account assumes that our face perception system has adapted to the faces we are typically exposed to, equipping it poorly for the processing of other-race faces. Sociocognitive theories assume that other-race faces are initially categorized as out-group, decreasing motivation to individuate them. Supporting sociocognitive accounts, a recent study has reported improved recognition for other-race faces when these were categorized as belonging to the participants' in-group on a second social dimension, i.e., their university affiliation. Faces were studied in groups, containing both own-race and other-race faces, half of each labeled as in-group and out-group, respectively. When study faces were spatially grouped by race, participants showed a clear own-race bias. When faces were grouped by university affiliation, recognition of other-race faces from the social in-group was indistinguishable from own-race face recognition. The present study aimed at extending this singular finding to other races of faces and participants. Forty Asian and 40 European Australian participants studied Asian and European faces for a recognition test. Faces were presented in groups, containing an equal number of own-university and other-university Asian and European faces. Between participants, faces were grouped either according to race or university affiliation. Eye tracking was used to study the distribution of spatial attention to individual faces in the display. The race of the study faces significantly affected participants' memory, with better recognition of own-race than other-race faces. However, memory was unaffected by the university affiliation of the faces and by the criterion for their spatial grouping on the display. Eye tracking revealed strong looking biases towards both own-race and own-university faces

  4. On the other side of the fence: effects of social categorization and spatial grouping on memory and attention for own-race and other-race faces.

    PubMed

    Kloth, Nadine; Shields, Susannah E; Rhodes, Gillian

    2014-01-01

    The term "own-race bias" refers to the phenomenon that humans are typically better at recognizing faces from their own than a different race. The perceptual expertise account assumes that our face perception system has adapted to the faces we are typically exposed to, equipping it poorly for the processing of other-race faces. Sociocognitive theories assume that other-race faces are initially categorized as out-group, decreasing motivation to individuate them. Supporting sociocognitive accounts, a recent study has reported improved recognition for other-race faces when these were categorized as belonging to the participants' in-group on a second social dimension, i.e., their university affiliation. Faces were studied in groups, containing both own-race and other-race faces, half of each labeled as in-group and out-group, respectively. When study faces were spatially grouped by race, participants showed a clear own-race bias. When faces were grouped by university affiliation, recognition of other-race faces from the social in-group was indistinguishable from own-race face recognition. The present study aimed at extending this singular finding to other races of faces and participants. Forty Asian and 40 European Australian participants studied Asian and European faces for a recognition test. Faces were presented in groups, containing an equal number of own-university and other-university Asian and European faces. Between participants, faces were grouped either according to race or university affiliation. Eye tracking was used to study the distribution of spatial attention to individual faces in the display. The race of the study faces significantly affected participants' memory, with better recognition of own-race than other-race faces. However, memory was unaffected by the university affiliation of the faces and by the criterion for their spatial grouping on the display. Eye tracking revealed strong looking biases towards both own-race and own-university faces

  5. Effect of acid labile ether protecting groups on the oxide etch resistance and lithographic performance of 248-nm resists

    NASA Astrophysics Data System (ADS)

    Varanasi, Pushkara R.; Cornett, Kathleen M.; Lawson, Margaret C.

    2000-06-01

    In our attempts to develop etch resistance 248 nm positive resists, we have designed and synthesized thermally stable and acid sensitive methylbenzyl ether (MBE) protected poly(hydroxystyrene) derivatives. Results presented in this paper clearly illustrate that the MBE protecting group provides superior etch resistance to conventional carbonate, ester and acetal/ketal based protecting groups. It is also shown that the MBE protecting group is thermally stable and undergoes acid catalyzed deprotection leading to preferential rearrangement products due to electrophilic ring substitution. Such a rearrangement is shown to provide a unique mechanism to reduce/eliminate resist shrinkage and improve lithographic performance.

  6. A combination of omega-3 fatty acids, folic acid and B-group vitamins is superior at lowering homocysteine than omega-3 alone: A meta-analysis.

    PubMed

    Dawson, Samantha Loren; Bowe, Steven John; Crowe, Timothy Charles

    2016-06-01

    The aim of the study was to assess whether omega-3 polyunsaturated fatty acid supplementation alone or in combination with folic acid and B-group vitamins is effective in lowering homocysteine. The Medline Ovid, Embase and Cochrane databases were searched for randomized-controlled trial studies that intervened with omega-3 supplementation (with or without folic acid) and measured changes in homocysteine concentration. Studies were pooled using a random effects model for meta-analysis. Three different models were analyzed: all trials combined, omega-3 polyunsaturated fatty acid trials, and omega-3 polyunsaturated fatty acids with folic acid and B-group vitamin trials. Nineteen studies were included, consisting of 3267 participants completing 21 trials. Studies were heterogeneous; varying by dose, duration and participant health conditions. Across all trials, omega-3 supplementation was effective in lowering homocysteine by an average of 1.18μmol/L (95%CI: (-1.89, -0.48), P=.001). The average homocysteine-lowering effect was greater when omega-3 supplementation was combined with folic acid and B-group vitamins (-1.37μmol/L, 95%CI: (-2.38, -0.36), P<.01) compared to omega-3 supplementation alone (-1.09μmol/L 95%CI: (-2.04, -0.13), P=.03). Omega-3 polyunsaturated fatty acid supplementation was associated with a modest reduction in homocysteine. For the purposes of reducing homocysteine, a combination of omega-3s (0.2-6g/day), folic acid (150 - 2500μg/day) and vitamins B6 and B12 may be more effective than omega-3 supplementation alone.

  7. Copoly(arylene ether)s containing pendant sulfonic acid groups as proton exchange membranes

    SciTech Connect

    Dae Sik, Kim; Yu Seung, Kim; Gilles, Robertson; Guiver, Michael D

    2009-01-01

    A copoly(arylene ether) (PAE) with high fluorine content and a copoly(arylene ether nitrile) (PAEN) with high nitrile content, each containing pendant phenyl sulfonic acids were synthesized. The PAE and P AEN were prepared from decafluorobiphenyl (DFBP) and difluorobenzonitrile (DFBN) respectively, by polycondensation with 2phenylhydroquinone (PHQ) by conventional aromatic nucleophilic substitution reactions. sulfonic acid groups were introduced by mild post-sulfonation exclusively on the para-position of the pendant phenyl ring in PHQ. The membrane properties of the resulting sulfonated copolymers sPAE and sPAEN were compared for fuel cell applications. The copolymers sPAE and sPAEN, each having a degree of sulfonation (OS) of 1.0 had high ion exchange capacities (IEC{sub v})(wet) (volume-based, wet state) of 1.77 and 2.55 meq./cm3, high proton conductivities of 135.4 and 140.1 mS/cm at 80 C, and acceptable volume-based water uptake of 44.5 -51.9 vol% at 80 C, respectively, compared to Nafion. The data points of these copolymer membranes are located in the upper left-hand corner in the trade-off plot of alternative hydrocarbon polyelectrolyte membranes (PEM) for the relationship between proton conductivity versus water uptake (weight based or volume based), i.e., high proton conductivity and low water uptake. Furthermore, the relative selectivity derived from proton conductivity and methanol permeability is higher than that of Nafion.

  8. Molecular Structures, Acid-Base Properties, and Formation of Group 6 Transition Metal Hydroxides

    SciTech Connect

    Li, Shenggang; Guenther, Courtney L.; Kelley, Matthew S.; Dixon, David A.

    2011-04-28

    Density functional theory (DFT) and coupled cluster theory (CCSD(T)) were used to study the group 6 metal (M = Cr, Mo, W) hydroxides: MO3-m(OH)2m (m = 1-3), M2O6-m(OH)2m (m = 1-5), M3O9-m(OH)2m (m = 1, 2), and M4O11(OH)2. The calculations were done up to the complete basis set (CBS) limit for the CCSD(T) method. Molecular structures of many low-energy conformers/isomers were located. Brønsted acidities in the gas phase and pKa values in aqueous solution were predicted for MO3-m(OH)2m (m = 1-3) and MnO3n-1(OH)2 (n = 2-4). In addition, Brønsted basicities and Lewis acidities (fluoride affinities) were predicted for MO3-m(OH)2m (m = 1-3) as well as the metal oxide clusters MnO3n (n = 1-3). The metal hydroxides were predicted to be strong Brønsted acids and weak to modest Brønsted bases and Lewis acids. The pKa values can have values as negative as -31. Potential energy surfaces for the hydrolysis of the MnO3n (n = 1-4) clusters were calculated. Heats of formation of the metal hydroxides were predicted from the calculated reaction energies, and the agreement with the limited available experimental data is good. The first hydrolysis step leading to the formation of MnO3n-1(OH)2 was predicted to be exothermic, with the exothermicity becoming less negative as n increases and essentially converged at n = 3. Reaction rate constants for the hydrogen transfer steps were calculated using transition state theory and RRKM theory. Further hydrolysis of MnO3n-1(OH)2 tends to be endothermic especially for M = Cr. Fifty-five DFT exchange-correlation functionals were benchmarked for the calculations of the reaction energies, complexation energies, and reaction barriers by comparing to our CCSD(T) results. Overall, the DFT results for the potential energy surfaces are semiquantitatively correct, but no single functional works for all processes and all three metals. Among the functionals benchmarked, the wB97, wB97X, B1B95, B97-1, mPW1LYP, and X3LYP functionals have the best

  9. Number of free hydroxyl groups on bile acid phospholipids determines the fluidity and hydration of model membranes.

    PubMed

    Sreekanth, Vedagopuram; Bajaj, Avinash

    2013-10-10

    Interactions of synthetic phospholipids with model membranes determines the drug release capabilities of phospholipid vesicles at diseased sites. We performed 1,6-diphenyl-1,3,5-hexatriene (DPH)-based fluorescence anisotropy, Laurdan-based membrane hydration, and differential scanning calorimetry (DSC) studies to cognize the interactions of three bile acid phospholipids, lithocholic acid-phosphocholine (LCA-PC), deoxycholic acid-phosphocholine (DCA-PC), and cholic acid-phosphocholine (CA-PC) with model membranes. These studies revealed that bile acid phospholipids increases membrane fluidity in DCA-PC > CA-PC > LCA-PC order, indicating that induction of membrane fluidity is contingent on the number and positioning of free hydroxyl groups on bile acids. Similarly, DCA-PC causes maximum membrane perturbations due to the presence of a free hydroxyl group, whereas LCA-PC induces gel phase in membranes due to hydrophobic bile acid acyl chain interactions. These DCA-PC-induced membrane perturbations induce a drastic decrease in phase transition temperature (Tm) as determined by calorimetric studies, whereas doping of LCA-PC causes phase transition broadening without change in Tm. Doping of CA-PC induces membrane perturbations and membrane hydration like DCA-PC but sharpening of phase transition at higher doping suggests self-association of CA-PC molecules. Therefore these differential mode of interactions between bile acid phospholipids and model membranes would help in the future for their use in drug delivery.

  10. Evaluation of the number of ionogenic groups of inulinase by acid-base titration.

    PubMed

    Kovaleva, T A; Holyavka, M G; Rezvan, S G; Kozhedub, S V

    2008-06-01

    Acid base titration showed that Aspergillus awamori inulinase includes 178 asparaginic and glutamic acid residues, 20 histidine, 10 serine, and 34 lysine and tyrosine residues. Denaturation temperature for this enzyme was calculated using analysis of the proportion of stabilizing and destabilizing amino acids in the molecule.

  11. Fecal microbes, short chain fatty acids, and colorectal cancer across racial/ethnic groups

    PubMed Central

    Hester, Christina M; Jala, Venkatakrishna R; Langille, Morgan GI; Umar, Shahid; Greiner, K Allen; Haribabu, Bodduluri

    2015-01-01

    AIM: To investigate differences in microbes and short chain fatty acid (SCFA) levels in stool samples from Hispanic and non-Hispanic African American, American Indian, and White participants. METHODS: Stool samples from twenty participants were subjected to analysis for relative levels of viable bacteria and for SCFA levels. Additionally, the samples were subjected to 16S rRNA gene pyrosequencing for identification of bacteria present in the stool. We used a metagenome functional prediction technique to analyze genome copy numbers and estimate the abundance of butyrate kinase in all samples. RESULTS: We found that African Americans had significantly lower levels of acetate, butyrate, and total SCFAs than all other racial/ethnic groups. We also found that participant microbial profiles differed by racial/ethnic group. African Americans had significantly more Firmicutes than Whites, with enriched Ruminococcaceae. The Firmicutes/Bacteroidetes ratio was also significantly higher for African Americans than for Whites (P = 0.049). We found Clostridium levels to be significantly and inversely related to total SCFA levels (P = 0.019) and we found Bacteroides to be positively associated (P = 0.027) and Clostridium to be negatively associated (P = 0.012) with levels of butyrate. We also identified a correlation between copy number for a butyrate kinase predicted from 16S rRNA gene abundance and levels of butyrate in stool. CONCLUSION: The identified differences in gut flora and SCFA levels may relate to colorectal cancer mortality differentials and may be useful as targets for future clinical and behavioral interventions. PMID:25759547

  12. Removal of textile dyes and metallic ions using polyelectrolytes and macroelectrolytes containing sulfonic acid groups.

    PubMed

    Caldera Villalobos, M; Peláez Cid, A A; Herrera González, Ana M

    2016-07-15

    This work reports the removal of textile dyes and metallic ions by means of adsorption and coagulation-flocculation using two polyelectrolytes and two macroelectrolytes containing sulfonic acid groups. The adsorption of textile dyes was studied in aqueous solutions containing cationic dyes and in wastewater containing a vat dye. Also, removal of vat and naphthol dyes was studied using the process of coagulation-flocculation. The results show these materials possess elevated adsorption capacity, and they accomplished removal rates above 97% in aqueous solutions. The removal of the vat dye improved the quality of the wastewater notably, and an uncolored effluent was obtained at the end of the treatment. The treatment using adsorption decreased the values for coloration, conductivity, suspended solids, and pH. The removal of vat and naphthol dyes by means of coagulation-flocculation was studied as well, and removal rates of 90% were obtained. The polyelectrolytes and macroelectrolytes also proved effective in the adsorption of metallic ions in wastewater. The treatment using adsorption accomplished high removal rates of metallic ions, and it showed greater selectivity towards Cu(2+), Fe(3+) and Pb(2+). A decrease in the content of solids as well as the values for COD and conductivity was observed in the wastewater as well. The analyses of FT-IR indicated that cationic dyes and metallic ions were chemisorbed by means of ionic exchange.

  13. Community Genomic and Proteomic Analyses of Chemoautotrophic Iron-Oxidizing "Leptospirillum rubarum" (Group II) and "Leptospirillum ferrodiazotrophum" (Group III) Bacteria in Acid Mine Drainage Biofilms

    SciTech Connect

    Goltsman, Daniela; Denef, Vincent; Singer, Steven; Verberkmoes, Nathan C; Lefsrud, Mark G; Mueller, Ryan; Dick, Gregory J.; Sun, Christine; Wheeler, Korin; Zelma, Adam; Baker, Brett J.; Hauser, Loren John; Land, Miriam L; Shah, Manesh B; Thelen, Michael P.; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2009-01-01

    We analyzed near-complete population (composite) genomic sequences for coexisting acidophilic iron-oxidizing Leptospirillum group II and III bacteria (phylum Nitrospirae) and an extrachromosomal plasmid from a Richmond Mine, Iron Mountain, CA, acid mine drainage biofilm. Community proteomic analysis of the genomically characterized sample and two other biofilms identified 64.6% and 44.9% of the predicted proteins of Leptospirillum groups II and III, respectively, and 20% of the predicted plasmid proteins. The bacteria share 92% 16S rRNA gene sequence identity and >60% of their genes, including integrated plasmid-like regions. The extrachromosomal plasmid carries conjugation genes with detectable sequence similarity to genes in the integrated conjugative plasmid, but only those on the extrachromosomal element were identified by proteomics. Both bacterial groups have genes for community-essential functions, including carbon fixation and biosynthesis of vitamins, fatty acids, and biopolymers (including cellulose); proteomic analyses reveal these activities. Both Leptospirillum types have multiple pathways for osmotic protection. Although both are motile, signal transduction and methyl-accepting chemotaxis proteins are more abundant in Leptospirillum group III, consistent with its distribution in gradients within biofilms. Interestingly, Leptospirillum group II uses a methyl-dependent and Leptospirillum group III a methyl-independent response pathway. Although only Leptospirillum group III can fix nitrogen, these proteins were not identified by proteomics. The abundances of core proteins are similar in all communities, but the abundance levels of unique and shared proteins of unknown function vary. Some proteins unique to one organism were highly expressed and may be key to the functional and ecological differentiation of Leptospirillum groups II and III.

  14. Equilibrium adsorption of caffeic, chlorogenic and rosmarinic acids on cationic cross-linked starch with quaternary ammonium groups.

    PubMed

    Simanaviciute, Deimante; Klimaviciute, Rima; Rutkaite, Ramune

    2017-02-01

    In the present study, the equilibrium adsorption of caffeic acid (CA) and its derivatives, namely, chlorogenic (CGA) and rosmarinic (RA) acids on cationic cross-linked starch (CCS) with degree of substitution of quaternary ammonium groups of 0.42 have been investigated in relation to the structure and acidity of phenolic acids. The Langmuir, Freundlich and Dubinin-Radushkevich adsorption models have been used to describe the equilibrium adsorption of CA, CGA and RA from their initial solutions and solutions having the equimolar amount of NaOH at different temperatures. In the case of adsorption from the initial solutions of acids the values of adsorption parameters were closely related to the dissociation constants of investigated acids. According to the increasing effectiveness of adsorption, phenolic acids could be arranged in the following order: CAacids solutions changed their sorption properties which became mostly related to the acids structure.

  15. Synthesis and properties of novel 2'-C,4'-C-ethyleneoxy-bridged 2'-deoxyribonucleic acids with exocyclic methylene groups.

    PubMed

    Osawa, Takashi; Obika, Satoshi; Hari, Yoshiyuki

    2016-10-12

    Three 2'-C,4'-C-ethyleneoxy-bridged 2'-deoxyribonucleic acids possessing six-membered bridges with 6'-oxygen and 8'-exocyclic methylene groups (methylene-EoDNAs) were designed and synthesized in nine to ten steps from 5-methyluridine. The methylene-EoDNA-modified oligonucleotides showed excellent binding affinity with target ssRNA and extremely high nuclease resistance compared with natural oligonucleotides. These results proved the potential of methylene-EoDNAs for nucleic acid based technology.

  16. Community genomic and proteomic analysis of chemoautotrophic, iron-oxidizing "Leptospirillum rubarum" (Group II) and Leptospirillum ferrodiazotrophum (Group III) in acid mine drainage biofilms

    SciTech Connect

    Goltsman, Daniela; Denef, Vincent; Singer, Steven; Verberkmoes, Nathan C; Lefsrud, Mark G; Mueller, Ryan; Dick, Gregory J.; Sun, Christine; Wheeler, Korin; Zelma, Adam; Baker, Brett J.; Hauser, Loren John; Land, Miriam L; Shah, Manesh B; Thelen, Michael P.; Hettich, Robert {Bob} L; Banfield, Jillian F.

    2009-01-01

    We analyzed near-complete population (composite) genomic sequences for coexisting acidophilic iron-oxidizing Leptospirillum Groups II and III bacteria (phylum Nitrospirae) and an extrachromosomal plasmid from a Richmond Mine, CA acid mine drainage (AMD) biofilm. Community proteomic analysis of the genomically characterized sample and two other biofilms identified 64.6% and 44.9% of the predicted proteins of Leptospirillum Groups II and III, respectively and 20% of the predicted plasmid proteins. The bacteria share 92% 16S rRNA gene sequence identity and > 60% of their genes, including integrated plasmid-like regions. The extrachromosomal plasmid encodes conjugation genes with detectable sequence similarity to genes in the integrated conjugative plasmid, but only those on the extrachromosomal element were identified by proteomics. Both bacteria have genes for community-essential functions, including carbon fixation, biosynthesis of vitamins, fatty acids and biopolymers (including cellulose); proteomic analyses reveal these activities. Both Leptospirillum types have multiple pathways for osmotic protection. Although both are motile, signal transduction and methyl-accepting chemotaxis proteins are more abundant in Leptospirillum Group III, consistent with its distribution in gradients within biofilms. Interestingly, Leptospirillum Group II uses a methyl-dependent and Leptospirillum Group III a methyl-independent response pathway. Although only Leptospirillum Group III can fix nitrogen, these proteins were not identified by proteomics. Abundances of core proteins are similar in all communities, but abundance levels of unique and shared proteins of unknown function vary. Some proteins unique to one organism were highly expressed and may be key to the functional and ecological differentiation of Leptospirillum Groups II and III.

  17. Characterization of acid functional groups of carbon dots by nonlinear regression data fitting of potentiometric titration curves

    NASA Astrophysics Data System (ADS)

    Alves, Larissa A.; de Castro, Arthur H.; de Mendonça, Fernanda G.; de Mesquita, João P.

    2016-05-01

    The oxygenated functional groups present on the surface of carbon dots with an average size of 2.7 ± 0.5 nm were characterized by a variety of techniques. In particular, we discussed the fit data of potentiometric titration curves using a nonlinear regression method based on the Levenberg-Marquardt algorithm. The results obtained by statistical treatment of the titration curve data showed that the best fit was obtained considering the presence of five Brønsted-Lowry acids on the surface of the carbon dots with constant ionization characteristics of carboxylic acids, cyclic ester, phenolic and pyrone-like groups. The total number of oxygenated acid groups obtained was 5 mmol g-1, with approximately 65% (∼2.9 mmol g-1) originating from groups with pKa < 6. The methodology showed good reproducibility and stability with standard deviations below 5%. The nature of the groups was independent of small variations in experimental conditions, i.e. the mass of carbon dots titrated and initial concentration of HCl solution. Finally, we believe that the methodology used here, together with other characterization techniques, is a simple, fast and powerful tool to characterize the complex acid-base properties of these so interesting and intriguing nanoparticles.

  18. Synthesis and solid-state NMR characterization of cubic mesoporous silica SBA-1 functionalized with sulfonic acid groups.

    PubMed

    Tsai, Hui-Hsu Gavin; Chiu, Po-Jui; Jheng, Guang-Liang; Ting, Chun-Chiang; Pan, Yu-Chi; Kao, Hsien-Ming

    2011-07-01

    Well-ordered cubic mesoporous silicas SBA-1 functionalized with sulfonic acid groups have been synthesized through in situ oxidation of mercaptopropyl groups with H(2)O(2) via co-condensation of tetraethoxysilane (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) templated by cetyltriethylammonium bromide (CTEABr) under strong acidic conditions. Various synthesis parameters such as the amounts of H(2)O(2) and MPTMS on the structural ordering of the resultant materials were systematically investigated. The materials thus obtained were characterized by a variety of techniques including powder X-ray diffraction (XRD), multinuclear solid-state Nuclear Magnetic Resonance (NMR) spectroscopy, (29)Si{(1)H} 2D HETCOR (heteronuclear correlation) NMR spectroscopy, thermogravimetric analysis (TGA), and nitrogen sorption measurements. By using (13)C CPMAS NMR technique, the status of the incorporated thiol groups and their transformation to sulfonic acid groups can be monitored and, as an extension, to define the optimum conditions to be used for the oxidation reaction to be quantitative. In particular, (29)Si{(1)H} 2D HETCOR NMR revealed that the protons in sulfonic acid groups are in close proximity to the silanol Q(3) species, but not close enough to form a hydrogen bond.

  19. Looking at Their Side of the Conflict? Effects of Single versus Multiple Perspective History Teaching on Jewish and Arab Adolescents' Attitude to Out-Group Narratives and In-Group Responsibility

    ERIC Educational Resources Information Center

    Goldberg, Tsafrir

    2014-01-01

    In the last decade, the issue of teaching the Palestinian perspective on the Jewish-Arab conflict in Israeli schools gave rise to considerable debate and competing curricula. A quasi-experimental study compared the effects of these competing approaches on learners' attitudes to out-group narratives and perceived in-group responsibility (IR). A…

  20. Elucidating and Regulating the Acetoin Production Role of Microbial Functional Groups in Multispecies Acetic Acid Fermentation

    PubMed Central

    Lu, Zhen-Ming; Liu, Na; Wang, Li-Juan; Wu, Lin-Huan; Gong, Jin-Song; Yu, Yong-Jian; Li, Guo-Quan; Shi, Jin-Song

    2016-01-01

    ABSTRACT Acetoin (3-hydroxy-2-butanone) formation in vinegar microbiota is crucial for the flavor quality of Zhenjiang aromatic vinegar, a traditional vinegar produced from cereals. However, the specific microorganisms responsible for acetoin formation in this centuries-long repeated batch fermentation have not yet been clearly identified. Here, the microbial distribution discrepancy in the diacetyl/acetoin metabolic pathway of vinegar microbiota was revealed at the species level by a combination of metagenomic sequencing and clone library analysis. The results showed that Acetobacter pasteurianus and 4 Lactobacillus species (Lactobacillus buchneri, Lactobacillus reuteri, Lactobacillus fermentum, and Lactobacillus brevis) might be functional producers of acetoin from 2-acetolactate in vinegar microbiota. Furthermore, A. pasteurianus G3-2, L. brevis 4-22, L. fermentum M10-3, and L. buchneri F2-5 were isolated from vinegar microbiota by a culture-dependent method. The acetoin concentrations in two cocultures (L. brevis 4-22 plus A. pasteurianus G3-2 and L. fermentum M10-3 plus A. pasteurianus G3-2) were obviously higher than those in monocultures of lactic acid bacteria (LAB), while L. buchneri F2-5 did not produce more acetoin when coinoculated with A. pasteurianus G3-2. Last, the acetoin-producing function of vinegar microbiota was regulated in situ via augmentation with functional species in vinegar Pei. After 72 h of fermentation, augmentation with A. pasteurianus G3-2 plus L. brevis 4-22, L. fermentum M10-3, or L. buchneri F2-5 significantly increased the acetoin content in vinegar Pei compared with the control group. This study provides a perspective on elucidating and manipulating different metabolic roles of microbes during flavor formation in vinegar microbiota. IMPORTANCE Acetoin (3-hydroxy-2-butanone) formation in vinegar microbiota is crucial for the flavor quality of Zhenjiang aromatic vinegar, a traditional vinegar produced from cereals. Thus, it is of

  1. Poly(ester amide)s based on (L)-lactic acid oligomers and α-amino acids: influence of the α-amino acid side chain in the poly(ester amide)s properties.

    PubMed

    Fonseca, Ana C; Coelho, Jorge F J; Valente, Joana F A; Correia, Tiago R; Correia, Ilídio J; Gil, Maria H; Simões, Pedro N

    2013-01-01

    Novel biodegradable and low cytotoxic poly(ester amide)s (PEAs) based on α-amino acids and (L)-lactic acid (L-LA) oligomers were successfully synthesized by interfacial polymerization. The chemical structure of the new polymers was confirmed by spectroscopic analyses. Further characterization suggests that the α-amino acid plays a critical role on the final properties of the PEA. L-phenylalanine provides PEAs with higher glass transition temperature, whereas glycine enhances the crystallinity. The hydrolytic degradation in PBS (pH = 7.4) at 37 °C also depends on the α-amino acid, being faster for glycine-based PEAs. The cytotoxic profiles using fibroblast human cells indicate that the PEAs did not elicit an acute cytotoxic effect. The strategy presented in this work opens the possibility of synthesizing biodegradable PEAs with low citotoxicity by an easy and fast method. It is worth to mention also that the properties of these materials can be fine-tuned only by changing the α-amino acid.

  2. Iron binding efficiency of polyphenols: Comparison of effect of ascorbic acid and ethylenediaminetetraacetic acid on catechol and galloyl groups.

    PubMed

    Tamilmani, Poonkodi; Pandey, Mohan Chandra

    2016-04-15

    Dietary polyphenols are markedly studied for their antioxidant activity. They also have a negative impact on nutrition whereby they interfere with iron absorption. Common dietary polyphenols include: catechins, flavonols, flavanols, flavones, anthocyanins, proanthocyanidins and phenolic acids. Ascorbic acid (AA) and Ethylenediaminetetraacetic acid (EDTA) are commonly used to counter act this reaction and increase iron bioavailability. This study was aimed at determining the effect of AA and EDTA on the catechol or galloyl iron binding ability of pure phenolics, coffee and tea. Phenolic concentrations of 40, 80, 610, 240, 320, 400, 520 and 900 μg/ml were tested against six levels of AA and EDTA. These effects were studied in detail using Multivariate Analysis of Variance (MANOVA) with the hypothesis that there would be one or more mean differences between the ratio of enhancer and the different concentrations of samples tested. AA was found to be more efficient than EDTA in a way that lesser quantity is required for completely overcoming negative iron binding effects of polyphenols and similar samples.

  3. Methylation of acidic moieties in poly(methyl methacrylate-co-methacrylic acid) copolymers for end-group characterization by tandem mass spectrometry.

    PubMed

    Giordanengo, Rémi; Viel, Stéphane; Hidalgo, Manuel; Allard-Breton, Béatrice; Thévand, André; Charles, Laurence

    2010-07-30

    The complete structural characterization of a copolymer composed of methacrylic acid (MAA) and methyl methacrylate (MMA) units was achieved using tandem mass spectrometry. In a first step, collision-induced dissociation (CID) of sodiated MAA-MMA co-oligomers allowed us to determine the co-monomeric composition, the random nature of the copolymer and the sum of the end-group masses. However, dissociation reactions of MAA-based molecules mainly involve the acidic pendant groups, precluding individual characterization of the end groups. Therefore, methylation of all the acrylic acid moieties was performed to transform the MAA-MMA copolymer into a PMMA homopolymer, for which CID mainly proceeds via backbone cleavages. Using trimethylsilyldiazomethane as a derivatization agent, this methylation reaction was shown to be complete without affecting the end groups. Using fragmentation rules established for PMMA polymers together with accurate mass measurements of the product ions and knowledge of reagents used for the studied copolymer synthesis, a structure could be proposed for both end groups and it was found to be consistent with signals obtained in nuclear magnetic resonance spectra.

  4. The Origin of Homochirality in Amino Acids Through Weak Neutral Currents and Ortho:Para Disequilibrium in the Amino Group

    NASA Astrophysics Data System (ADS)

    Popa, R.; Cimpoiasu, V. M.; Scorei, R. I.

    2010-04-01

    We report finding chiral disruption in the amino acid Asparagine. Our model is based on weak neutral currents from the chiral center producing L-D-asymmetric organization of the amino group. This effect is measurable by H217O-TD-1HNMR.

  5. Voltammetric Detection of Oxalic Acid by Using Glassy Carbon Electrodes with Covalently Attached Nitrogen-containing Functional Groups.

    PubMed

    Matsuura, Hiroaki; Akabe, Syuhei; Kitamura, Tsubasa; Takahashi, Takuto; Uchiyama, Shunichi

    2015-01-01

    We report on a novel voltammetric detection of oxalic acid by using glassy carbon electrodes with covalently attached nitrogen-containing functional groups prepared by stepwise electrolysis. A glassy carbon electrode electrooxidized in an ammonium carbamate solution was electroreduced at -1.0 V (vs. Ag/AgCl) in 1.0 M sulfuric acid for a long time. We found that the electrocatalytic oxidation wave of oxalic acid obtained by this modified glassy carbon electrode was moved to a more negative potential region than that obtained by a platinum electrode in an acidic medium. A good linearity for the peak current signals was observed in the concentration range from 0.1 to 50 mM.

  6. Pristine environments harbor a new group of oligotrophic 2,4-dichlorophenoxyacetic acid-degrading bacteria.

    PubMed Central

    Kamagata, Y; Fulthorpe, R R; Tamura, K; Takami, H; Forney, L J; Tiedje, J M

    1997-01-01

    2,4-Dichlorophenoxyacetic acid (2,4-D)-degrading bacteria were isolated from pristine environments which had no history of 2,4-D exposure. By using 2,4-D dye indicator medium or 14C-labeled 2,4-D medium, six strains were isolated from eight enrichment cultures capable of degrading 2,4-D. Phylogenetic analyses based on 16S ribosomal DNA (rDNA) sequencing and physiological properties revealed that one isolate from Hawaiian volcanic soil could be classified in the genus Variovorax (a member of the beta subdivision of the class Proteobacteria) and that the other five isolates from Hawaiian volcanic soils, Saskatchewan forest soil, and Chilean forest soil have 16S rDNAs with high degrees of similarity to those of the Bradyrhizobium group (a member of the alpha subdivision of the class Proteobacteria). All the isolates grow slowly on either nutrient media (0.1 x Bacto Peptone-tryptone-yeast extract-glucose [PTYG] or 0.1 x Luria broth [LB] medium) or 2,4-D medium, with mean generation times of 16 to 30 h, which are significantly slower than previously known 2,4-D degraders. Nutrient-rich media such as full-strength PTYG and LB medium did not allow their growth. PCR amplification using internal consensus sequences of tfdA (a gene encoding an enzyme for the first step of 2,4-D mineralization, found in pJP4 of Alcaligenes eutrophus JMP134 and some other 2,4-D-degrading bacteria) as primers and Southern hybridization with pJP4-tfdA as a probe revealed that the isolate belonging to the genus Variovorax carried the tfdA gene. This gene was transmissible to A. eutrophus JMP228 carrying a plasmid with a mutant tfdA gene. The other five isolates did not appear to carry tfdA, and 2,4-D-specific alpha-ketoglutarate-dependent dioxygenase activity could not be detected in cell lysates. These results indicate that 2,4-D-degrading bacteria in pristine environments are slow-growing bacteria and that most of their phylogenies and catabolic genes differ from those of 2,4-D degraders

  7. 5'to 3' nucleic acid synthesis using 3'-photoremovable protecting group

    DOEpatents

    Pirrung, Michael C.; Shuey, Steven W.; Bradley, Jean-Claude

    1999-01-01

    The present invention relates, in general, to a method of synthesizing a nucleic acid, and, in particular, to a method of effecting 5' to 3' nucleic acid synthesis. The method can be used to prepare arrays of oligomers bound to a support via their 5' end. The invention also relates to a method of effecting mutation analysis using such arrays. The invention further relates to compounds and compositions suitable for use in such methods.

  8. 5[prime] to 3[prime] nucleic acid synthesis using 3[prime]-photoremovable protecting group

    DOEpatents

    Pirrung, M.C.; Shuey, S.W.; Bradley, J.C.

    1999-06-01

    The present invention relates, in general, to a method of synthesizing a nucleic acid, and, in particular, to a method of effecting 5[prime] to 3[prime] nucleic acid synthesis. The method can be used to prepare arrays of oligomers bound to a support via their 5[prime] end. The invention also relates to a method of effecting mutation analysis using such arrays. The invention further relates to compounds and compositions suitable for use in such methods.

  9. Changes in conformational dynamics of basic side chains upon protein–DNA association

    PubMed Central

    Esadze, Alexandre; Chen, Chuanying; Zandarashvili, Levani; Roy, Sourav; Pettitt, B. Montgometry; Iwahara, Junji

    2016-01-01

    Basic side chains play major roles in recognition of nucleic acids by proteins. However, dynamic properties of these positively charged side chains are not well understood. In this work, we studied changes in conformational dynamics of basic side chains upon protein–DNA association for the zinc-finger protein Egr-1. By nuclear magnetic resonance (NMR) spectroscopy, we characterized the dynamics of all side-chain cationic groups in the free protein and in the complex with target DNA. Our NMR order parameters indicate that the arginine guanidino groups interacting with DNA bases are strongly immobilized, forming rigid interfaces. Despite the strong short-range electrostatic interactions, the majority of the basic side chains interacting with the DNA phosphates exhibited high mobility, forming dynamic interfaces. In particular, the lysine side-chain amino groups exhibited only small changes in the order parameters upon DNA-binding. We found a similar trend in the molecular dynamics (MD) simulations for the free Egr-1 and the Egr-1–DNA complex. Using the MD trajectories, we also analyzed side-chain conformational entropy. The interfacial arginine side chains exhibited substantial entropic loss upon binding to DNA, whereas the interfacial lysine side chains showed relatively small changes in conformational entropy. These data illustrate different dynamic characteristics of the interfacial arginine and lysine side chains. PMID:27288446

  10. Acetic acid bacteria: A group of bacteria with versatile biotechnological applications.

    PubMed

    Saichana, Natsaran; Matsushita, Kazunobu; Adachi, Osao; Frébort, Ivo; Frebortova, Jitka

    2015-11-01

    Acetic acid bacteria are gram-negative obligate aerobic bacteria assigned to the family Acetobacteraceae of Alphaproteobacteria. They are members of the genera Acetobacter, Gluconobacter, Gluconacetobacter, Acidomonas, Asaia, Kozakia, Swaminathania, Saccharibacter, Neoasaia, Granulibacter, Tanticharoenia, Ameyamaea, Neokomagataea, and Komagataeibacter. Many strains of Acetobacter and Komagataeibacter have been known to possess high acetic acid fermentation ability as well as the acetic acid and ethanol resistance, which are considered to be useful features for industrial production of acetic acid and vinegar, the commercial product. On the other hand, Gluconobacter strains have the ability to perform oxidative fermentation of various sugars, sugar alcohols, and sugar acids leading to the formation of several valuable products. Thermotolerant strains of acetic acid bacteria were isolated in order to serve as the new strains of choice for industrial fermentations, in which the cooling costs for maintaining optimum growth and production temperature in the fermentation vessels could be significantly reduced. Genetic modifications by adaptation and genetic engineering were also applied to improve their properties, such as productivity and heat resistance.

  11. Orientation Preferences of Backbone Secondary Amide Functional Groups in Peptide Nucleic Acid Complexes: Quantum Chemical Calculations Reveal an Intrinsic Preference of Cationic D-Amino Acid-Based Chiral PNA Analogues for the P-form

    SciTech Connect

    Smith, Jeremy C; Topham, Christopher

    2007-01-01

    Geometric descriptions of nonideal interresidue hydrogen bonding and backbone-base water bridging in the minor groove are established in terms of polyamide backbone carbonyl group orientation from analyses of residue junction conformers in experimentally determined peptide nucleic acid (PNA) complexes. Two types of interresidue hydrogen bonding are identified in PNA conformers in heteroduplexes with nucleic acids that adopt A-like base pair stacking. Quantum chemical calculations on the binding of a water molecule to an O2 base atom in glycine-based PNA thymine dimers indicate that junctions modeled with P-form backbone conformations are lower in energy than a dimer comprising the predominant conformation observed in A-like helices. It is further shown in model systems that PNA analogs based on D-lysine are better able to preorganize in a conformation exclusive to P-form helices than is glycine-based PNA. An intrinsic preference for this conformation is also exhibited by positively charged chiral PNA dimers carrying 3-amino-D-alanine or 4-aza-D-leucine residue units that provide for additional rigidity by side-chain hydrogen bonding to the backbone carbonyl oxygen. Structural modifications stabilizing P-form helices may obviate the need for large heterocycles to target DNA pyrimidine bases via PNADNA-PNA triplex formation. Quantum chemical modeling methods are used to propose candidate PNA Hoogsteen strand designs.

  12. A Clostridium Group IV Species Dominates and Suppresses a Mixed Culture Fermentation by Tolerance to Medium Chain Fatty Acids Products

    PubMed Central

    Andersen, Stephen J.; De Groof, Vicky; Khor, Way Cern; Roume, Hugo; Props, Ruben; Coma, Marta; Rabaey, Korneel

    2017-01-01

    A microbial community is engaged in a complex economy of cooperation and competition for carbon and energy. In engineered systems such as anaerobic digestion and fermentation, these relationships are exploited for conversion of a broad range of substrates into products, such as biogas, ethanol, and carboxylic acids. Medium chain fatty acids (MCFAs), for example, hexanoic acid, are valuable, energy dense microbial fermentation products, however, MCFA tend to exhibit microbial toxicity to a broad range of microorganisms at low concentrations. Here, we operated continuous mixed population MCFA fermentations on biorefinery thin stillage to investigate the community response associated with the production and toxicity of MCFA. In this study, an uncultured species from the Clostridium group IV (related to Clostridium sp. BS-1) became enriched in two independent reactors that produced hexanoic acid (up to 8.1 g L−1), octanoic acid (up to 3.2 g L−1), and trace concentrations of decanoic acid. Decanoic acid is reported here for the first time as a possible product of a Clostridium group IV species. Other significant species in the community, Lactobacillus spp. and Acetobacterium sp., generate intermediates in MCFA production, and their collapse in relative abundance resulted in an overall production decrease. A strong correlation was present between the community composition and both the hexanoic acid concentration (p = 0.026) and total volatile fatty acid concentration (p = 0.003). MCFA suppressed species related to Clostridium sp. CPB-6 and Lactobacillus spp. to a greater extent than others. The proportion of the species related to Clostridium sp. BS-1 over Clostridium sp. CPB-6 had a strong correlation with the concentration of octanoic acid (p = 0.003). The dominance of this species and the increase in MCFA resulted in an overall toxic effect on the mixed community, most significantly on the Lactobacillus spp., which resulted in a decrease in total

  13. Phytochemical Analysis, Antioxidant Activity, Fatty Acids Composition, and Functional Group Analysis of Heliotropium bacciferum

    PubMed Central

    Ahmad, Sohail; Ahmad, Shabir; Bibi, Ahtaram; Ishaq, Muhammad Saqib; Afridi, Muhammad Siddique; Kanwal, Farina; Zakir, Muhammad; Fatima, Farid

    2014-01-01

    Heliotropium bacciferum is paramount in medicinal perspective and belongs to Boraginaceae family. The crude and numerous fractions of leaves, stem, and roots of the plant were investigated for phytochemical analysis and DPPH radical scavenging activity. Phytochemical analysis of crude and fractions of the plant revealed the presence of alkaloids, saponins, tannins, steroids, terpenoids, flavonoids, glycosides, and phenols. The antioxidant (free radical scavenging) activity of various extracts of the Heliotropium bacciferum was resolute against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical with the avail of UV spectrophotometer at 517 nm. The stock solution (1000 mg/mL) and then several dilutions (50, 100, 150, 200, and 250 mg/mL) of the crude and fractions were prepared. Ascorbic acid was used as a standard. The plant leaves (52.59 ± 0.84 to 90.74 ± 1.00), stem (50.19 ± 0.92 to 89.42 ± 1.10), and roots extracts (49.19 ± 0.52 to 90.01 ± 1.02) divulged magnificent antioxidant activities. For the ascertainment of the fatty acid constituents a gas chromatograph hyphenated to mass spectrometer was used. The essential fatty acids for growth maintenance such as linoleic acid (65.70%), eicosadienoic acid (15.12%), oleic acid (8.72%), and palmitic acid (8.14%) were found in high percentage. The infrared spectra of all extracts of the plant were recorded by IR Prestige-21 FTIR model. PMID:25489605

  14. Adducts of hexamethylenetetramine with ferrocenecarboxylic acid and ferrocene-1,1'-dicarboxylic acid: multiple disorder in space groups Fmm2 and Cmcm.

    PubMed

    Zakaria, Choudhury M; Ferguson, George; Lough, Alan J; Glidewell, Christopher

    2003-07-01

    Hexamethylenetetramine, C(6)H(12)N(4), and ferrocenecarboxylic acid, C(11)H(10)FeO(2), form a 1:2 adduct, (I), which is a salt, viz. hexamethylenetetraminium(2+) bis(ferrocenecarboxylate), (C(6)H(14)N(4))[Fe(C(5)H(5))(C(6)H(4)O(2))](2). The dication in (I) is disordered with two orientations at a site of mm2 symmetry in space group Fmm2, while the anion lies across a mirror plane with its unsubstituted cyclopentadienyl ring disordered over two sets of sites. With ferrocene-1,1'-dicarboxylic acid, C(12)H(10)FeO(4), hexamethylenetetramine forms a 1:1 adduct, (II), in which both components are neutral, viz. hexamethylenetetramine-ferrocene-1,1'-dicarboxylic acid (1/1), [Fe(C(6)H(5)O(2))(2)].C(6)H(12)N(4). The amine component in (II) is disordered with two orientations at a site of mm2 symmetry in space group Cmcm, while the acid component is disordered with two orientations at a site of 2/m symmetry. The components in (I) are linked into a finite three-ion aggregate by a single N-H.O hydrogen bond, while the components of (II) are linked into continuous chains by a single O-H.N hydrogen bond.

  15. How the extra methylene group affects the ligation properties of Glu vs. Asp and Gln vs. Asn amino acids: a DFT/PCM study.

    PubMed

    Dudev, Todor; Doudeva, Lyudmila

    2017-02-01

    The effect of the extra methylene group on the ligation properties of glutamic (Glu) vs. aspartic (Asp) acid, and glutamine (Gln) vs. asparagine (Asn) amino acids-two pairs of protein building blocks differing by the length of their side chains-has been studied by employing DFT calculations combined with polarizable continuum model (PCM) computations. Complexes of the nominal species with partner ligands of various structures, charge states, and degree of solvent exposure have been examined. The results obtained reveal that the difference in the alkyl chain length of these amino acid residues does not affect the mode of their binding. This, however, influences the thermodynamics of the ligand-ligand and ligand-metal recognition thus bestowing unique ligation characteristics on the competing entities. The calculations reveal that the competition between the longer-chain and shorter-chain analogs is entropy driven and that the differential electronic effects are of minor importance for the process. Thus, the outcome of the rivalry between Asp and Glu, and Asn and Gln is almost unaffected by the nature of the partner ligand, its charge state and, in most cases, the dielectric properties of the binding site. The longer-chain Glu, as opposed to its shorter-chain Asp counterpart, is the preferred partner ligand in various protein binding sites. Contrariwise, the shorter-chain Asn binds more favorably to the respective binding sites than its longer-chain Gln analog. The results obtained shed additional light on the intimate mechanism of the ligand-ligand and ligand-metal recognition in proteins and could be employed as guidelines in protein engineering and design.

  16. Synthesis of polyphosphazenes with sulfonimide side groups

    DOEpatents

    Allcock, Harry R.; Hofmann,; Michael A.; Ambler, Catherine M.; Andrew, Maher E.; Wood, Richard M.; Welna, Daniel T.

    2010-07-27

    The invention relates to sulfonimide bearing phenolic compounds and the use of those compounds to produce polyphosphazenes functionalized by one or more of those compounds alone, or in combination with cosubstituents. The invention also relates to blends of sulfonimide functionalized phosphazene polymers with other polymers, membranes formed of the functionalized polymers, and the use of those membranes in devices such as fuel cells.

  17. Carboxylic acids as traceless directing groups for the rhodium(III)-catalyzed decarboxylative C-H arylation of thiophenes.

    PubMed

    Zhang, Yuanfei; Zhao, Huaiqing; Zhang, Min; Su, Weiping

    2015-03-16

    A rhodium(III)-catalyzed carboxylic acid directed decarboxylative C-H/C-H cross-coupling of carboxylic acids with thiophenes has been developed. With a slight adjustment of the reaction conditions based on the nature of the substrates, aryl carboxylic acids with a variety of substituents could serve as suitable coupling partners, and a broad variety of functional groups were tolerated. This method provides straightforward access to biaryl scaffolds with diverse substitution patterns, many of which have conventionally been synthesized through lengthy synthetic sequences. An illustrative example is the one-step gram-scale synthesis of a biologically active 3,5-substituted 2-arylthiophene by way of the current method.

  18. Hydrogen-bond acidity of OH groups in various molecular environments (phenols, alcohols, steroid derivatives, and amino acids structures): experimental measurements and density functional theory calculations.

    PubMed

    Graton, Jérôme; Besseau, François; Brossard, Anne-Marie; Charpentier, Eloïse; Deroche, Arnaud; Le Questel, Jean-Yves

    2013-12-12

    The hydrogen-bond (H-bond) donating strengths of a series of 36 hydroxylic H-bond donors (HBDs) with N-methylpyrrolidinone have been measured in CCl4 solution by FTIR spectrometry. These data allow the definition of a H-bond acidity scale named pKAHY covering almost three pK units, corresponding to 16 kJ mol(-1). These results are supplemented by equilibrium constants determined in CH2Cl2 for one-third of the data set to study compounds showing a poor solubility in CCl4. A systematic comparison of these experimental results with theoretical data computed in the gas phase using DFT (density functional theory) calculations has also been carried out. Quantum electrostatic parameters appear to accurately describe the H-bond acidity of the hydroxyl group, whereas partial atomic charges according to the Merz-Singh-Kollman and CHelpG schemes are not suitable for this purpose. A substantial decrease of the H-bond acidity of the OH group is pointed out when the hydroxyl moiety is involved in intramolecular H-bond interactions. In such situations, the interactions are further characterized through AIM and NBO analyses, which respectively allow localizing the corresponding bond critical point and the quantification of a significant charge transfer from the available lone pair to the σ*OH antibonding orbital. Eventually, the H-bond ability of the hydroxyl groups of steroid derivatives and of lateral chains of amino acids are evaluated on the basis of experimental and/or theoretical data.

  19. Effect of Strong Acid Functional Groups on Electrode Rise Potential in Capacitive Mixing by Double Layer Expansion

    SciTech Connect

    Hatzell, Marta C.; Raju, Muralikrishna; Watson, Valerie J.; Stack, Andrew G.; van Duin, Adri C. T.; Logan, Bruce E.

    2014-11-03

    We report that the amount of salinity-gradient energy that can be obtained through capacitive mixing based on double layer expansion depends on the extent the electric double layer (EDL) is altered in a low salt concentration (LC) electrolyte (e.g., river water). We show that the electrode-rise potential, which is a measure of the EDL perturbation process, was significantly (P = 10–5) correlated to the concentration of strong acid surface functional groups using five types of activated carbon. Electrodes with the lowest concentration of strong acids (0.05 mmol g–1) had a positive rise potential of 59 ± 4 mV in the LC solution, whereas the carbon with the highest concentration (0.36 mmol g–1) had a negative rise potential (₋31 ± 5 mV). Chemical oxidation of a carbon (YP50) using nitric acid decreased the electrode rise potential from 46 ± 2 mV (unaltered) to ₋6 ± 0.5 mV (oxidized), producing a whole cell potential (53 ± 1.7 mV) that was 4.4 times larger than that obtained with identical electrode materials (from 12 ± 1 mV). Changes in the EDL were linked to the behavior of specific ions in a LC solution using molecular dynamics and metadynamics simulations. The EDL expanded in the LC solution when a carbon surface (pristine graphene) lacked strong acid functional groups, producing a positive-rise potential at the electrode. In contrast, the EDL was compressed for an oxidized surface (graphene oxide), producing a negative-rise electrode potential. In conclusion, these results established the linkage between rise potentials and specific surface functional groups (strong acids) and demonstrated on a molecular scale changes in the EDL using oxidized or pristine carbons.

  20. Effect of strong acid functional groups on electrode rise potential in capacitive mixing by double layer expansion.

    PubMed

    Hatzell, Marta C; Raju, Muralikrishna; Watson, Valerie J; Stack, Andrew G; van Duin, Adri C T; Logan, Bruce E

    2014-12-02

    The amount of salinity-gradient energy that can be obtained through capacitive mixing based on double layer expansion depends on the extent the electric double layer (EDL) is altered in a low salt concentration (LC) electrolyte (e.g., river water). We show that the electrode-rise potential, which is a measure of the EDL perturbation process, was significantly (P = 10(–5)) correlated to the concentration of strong acid surface functional groups using five types of activated carbon. Electrodes with the lowest concentration of strong acids (0.05 mmol g(–1)) had a positive rise potential of 59 ± 4 mV in the LC solution, whereas the carbon with the highest concentration (0.36 mmol g(–1)) had a negative rise potential (−31 ± 5 mV). Chemical oxidation of a carbon (YP50) using nitric acid decreased the electrode rise potential from 46 ± 2 mV (unaltered) to −6 ± 0.5 mV (oxidized), producing a whole cell potential (53 ± 1.7 mV) that was 4.4 times larger than that obtained with identical electrode materials (from 12 ± 1 mV). Changes in the EDL were linked to the behavior of specific ions in a LC solution using molecular dynamics and metadynamics simulations. The EDL expanded in the LC solution when a carbon surface (pristine graphene) lacked strong acid functional groups, producing a positive-rise potential at the electrode. In contrast, the EDL was compressed for an oxidized surface (graphene oxide), producing a negative-rise electrode potential. These results established the linkage between rise potentials and specific surface functional groups (strong acids) and demonstrated on a molecular scale changes in the EDL using oxidized or pristine carbons.

  1. Effect of Strong Acid Functional Groups on Electrode Rise Potential in Capacitive Mixing by Double Layer Expansion

    DOE PAGES

    Hatzell, Marta C.; Raju, Muralikrishna; Watson, Valerie J.; ...

    2014-11-03

    We report that the amount of salinity-gradient energy that can be obtained through capacitive mixing based on double layer expansion depends on the extent the electric double layer (EDL) is altered in a low salt concentration (LC) electrolyte (e.g., river water). We show that the electrode-rise potential, which is a measure of the EDL perturbation process, was significantly (P = 10–5) correlated to the concentration of strong acid surface functional groups using five types of activated carbon. Electrodes with the lowest concentration of strong acids (0.05 mmol g–1) had a positive rise potential of 59 ± 4 mV in themore » LC solution, whereas the carbon with the highest concentration (0.36 mmol g–1) had a negative rise potential (₋31 ± 5 mV). Chemical oxidation of a carbon (YP50) using nitric acid decreased the electrode rise potential from 46 ± 2 mV (unaltered) to ₋6 ± 0.5 mV (oxidized), producing a whole cell potential (53 ± 1.7 mV) that was 4.4 times larger than that obtained with identical electrode materials (from 12 ± 1 mV). Changes in the EDL were linked to the behavior of specific ions in a LC solution using molecular dynamics and metadynamics simulations. The EDL expanded in the LC solution when a carbon surface (pristine graphene) lacked strong acid functional groups, producing a positive-rise potential at the electrode. In contrast, the EDL was compressed for an oxidized surface (graphene oxide), producing a negative-rise electrode potential. In conclusion, these results established the linkage between rise potentials and specific surface functional groups (strong acids) and demonstrated on a molecular scale changes in the EDL using oxidized or pristine carbons.« less

  2. Metal-organic coordination architectures of azole heterocycle ligands bearing acetic acid groups: Synthesis, structure and magnetic properties

    SciTech Connect

    Hu Bowen; Zhao Jiongpeng; Yang Qian; Hu Tongliang; Du Wenping; Bu Xianhe

    2009-10-15

    Four new coordination complexes with azole heterocycle ligands bearing acetic acid groups, [Co(L{sup 1}){sub 2}]{sub n} (1), [CuL{sup 1}N{sub 3}]{sub n} (2), [Cu(L{sup 2}){sub 2}.0.5C{sub 2}H{sub 5}OH.H{sub 2}O]{sub n} (3) and [Co(L{sup 2}){sub 2}]{sub n} (4) (here, HL{sup 1}=1H-imidazole-1-yl-acetic acid, HL{sup 2}=1H-benzimidazole-1-yl-acetic acid) have been synthesized and structurally characterized. Single-crystal structure analysis shows that 3 and 4 are 2D complexes with 4{sup 4}-sql topologies, while another 2D complex 1 has a (4{sup 3}){sub 2}(4{sup 6})-kgd topology. And 2 is a 3D complex composed dinuclear mu{sub 1,1}-bridging azido Cu{sup II} entities with distorted rutile topology. The magnetic properties of 1 and 2 have been studied. - Graphical Abstract: The synthesis, crystal structure, and magnetic properties of the new coordination complexes with azole heterocycle ligands bearing acetic acid groups are reported.

  3. Synthesis and bioactivities of Phenazine-1-carboxylic acid derivatives based on the modification of PCA carboxyl group.

    PubMed

    Xiong, Zhipeng; Niu, Junfan; Liu, Hao; Xu, Zhihong; Li, Junkai; Wu, Qinglai

    2017-03-08

    Phenazine-1-carboxylic acid (PCA) as a natural product widely exists in microbial metabolites of Pseudomonads and Streptomycetes and has been registered for the fungicide against rice sheath blight in China. To find higher fungicidal activities compounds and study the effects on fungicidal activities after changing the carboxyl group of PCA, we synthesized a series of PCA derivatives by modifying the carboxyl group of PCA and their structures were confirmed by (1)H NMR and HRMS. Most compounds exhibited significant fungicidal activities in vitro. In particular, compound 6 exhibited inhibition effect against Rhizoctonia solani with EC50 values of 4.35mg/L and compound 3b exhibited effect against Fusarium graminearum with EC50 values of 8.30mg/L, compared to the positive control PCA with its EC50 values of 7.88mg/L (Rhizoctonia solani) and 127.28mg/L (Fusarium graminearum), respectively. The results indicated that the carboxyl group of PCA could be modified to be amide group, acylhydrazine group, ester group, methyl, hydroxymethyl, chloromethyl and ether group etc. And appropriate modifications on carboxyl group of PCA were useful to extend the fungicidal scope.

  4. Identification and Analysis of a Novel Group of Bacteriophages Infecting the Lactic Acid Bacterium Streptococcus thermophilus

    PubMed Central

    McDonnell, Brian; Mahony, Jennifer; Neve, Horst; Hanemaaijer, Laurens; Noben, Jean-Paul; Kouwen, Thijs

    2016-01-01

    ABSTRACT We present the complete genome sequences of four members of a novel group of phages infecting Streptococcus thermophilus, designated here as the 987 group. Members of this phage group appear to have resulted from genetic exchange events, as evidenced by their “hybrid” genomic architecture, exhibiting DNA sequence relatedness to the morphogenesis modules of certain P335 group Lactococcus lactis phages and to the replication modules of S. thermophilus phages. All four identified members of the 987 phage group were shown to elicit adsorption affinity to both their cognate S. thermophilus hosts and a particular L. lactis starter strain. The receptor binding protein of one of these phages (as a representative of this novel group) was defined using an adsorption inhibition assay. The emergence of a novel phage group infecting S. thermophilus highlights the continuous need for phage monitoring and development of new phage control measures. IMPORTANCE Phage predation of S. thermophilus is an important issue for the dairy industry, where viral contamination can lead to fermentation inefficiency or complete fermentation failure. Genome information and phage-host interaction studies of S. thermophilus phages, particularly those emerging in the marketplace, are an important part of limiting the detrimental impact of these viruses in the dairy environment. PMID:27316953

  5. Trivalent chromium removal from aqueous solutions by a sol–gel synthesized silica adsorbent functionalized with sulphonic acid groups

    SciTech Connect

    Gomez-Gonzalez, Sergio Efrain; Carbajal-Arizaga, Gregorio Guadalupe; Manriquez-Gonzalez, Ricardo; De la Cruz-Hernandez, Wencel; Gomez-Salazar, Sergio

    2014-11-15

    Highlights: • Corpuscular sulphonic acid-functionalized silica holds improved uptake of chromium. • Mesopores on adsorbent facilitate (CH{sub 3}COO){sub 2}Cr{sup +} ion uptake on sulphonate sites. • Formation of chromium acetate sulphonate complex proposed from XPS results. • Fixed bed chromium uptake results suggest potential industrial use. - Abstract: A high capacity hybrid silica adsorbent was synthesized via sol–gel processing with sulphonic acid groups as trivalent chromium complex ions chelators from aqueous solutions. The synthesis included co-condensation of tetraethoxysilane (TEOS) with 3-(mercaptopropyl)trimethoxysilane (MPS), and oxidation of thiol to sulphonic acid groups. Chromium uptake kinetic, batch and fixed-bed experiments were performed to assess the removal of this metal from aqueous solutions. {sup 13}C, {sup 29}Si CPMAS NMR, FTIR, XPS were used to characterize the adsorbent structure and the nature of chromium complexes on the adsorbent surface. Chromium maximum uptake was obtained at pH 3 (72.8 mg/g). Elemental analysis results showed ligand density of 1.48 mmol sulphonic groups/g. About 407 mL of Cr(III) solution (311 mg/L) were treated to breakthrough point reaching ≤0.06 mg/L at the effluent. These results comply with USEPA regulation for chromium concentration in drinking water (≤0.1 mg/L). The adsorbent shows potential to be used in chromium separations to the industrial level.

  6. Hyaluronic acid nanogels with enzyme-sensitive cross-linking group for drug delivery.

    PubMed

    Yang, Chenchen; Wang, Xin; Yao, Xikuang; Zhang, Yajun; Wu, Wei; Jiang, Xiqun

    2015-05-10

    A methacrylation strategy was employed to functionalize hyaluronic acid and prepare hyaluronic acid (HA) nanogels. Dynamic light scattering, zeta potential analyzer and electron microscopy were utilized to characterize the nanogels and their enzyme-degradability in vitro. It was found that these nanogels had a spherical morphology with the diameter of about 70nm, and negative surface potential. When doxorubicin (DOX) was loaded into the nanogels, the diameter decreased to approximately 50nm with a drug loading content of 16% and encapsulation efficiency of 62%. Cellular uptake examinations showed that HA nanogels could be preferentially internalized by two-dimensional (2D) cells and three-dimensional (3D) multicellular spheroids (MCs) which both overexpress CD44 receptor. Near-infrared fluorescence imaging, biodistribution and penetration examinations in tumor tissue indicated that the HA nanogels could efficiently accumulate and penetrate the tumor matrix. In vivo antitumor evaluation found that DOX-loaded HA nanogels exhibited a significantly superior antitumor effect.

  7. Synthesis and evaluation of novel dental monomer with branched carboxyl acid group

    PubMed Central

    Song, Linyong; Ye, Qiang; Ge, Xueping; Misra, Anil; Laurence, Jennifer S.; Berrie, Cynthia L.; Spencer, Paulette

    2014-01-01

    To enhance the water miscibility and increase the mechanical properties of dentin adhesives, a new glycerol-based monomer with vinyl and carboxylic acid, 4-((1,3-bis(-methacryloyloxy)propan-2-yl)oxy)-2-methylene-4-oxobutanoic acid (BMPMOB), was synthesized and characterized. Dentin adhesive formulations containing 2-hydroxyethyl methacrylate (HEMA), 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (BisGMA), and BMPMOB were characterized with regard to real-time photopolymerization behavior, water sorption, dynamic mechanical analysis, and microscale three-dimensional internal morphologies and compared with HEMA/BisGMA controls. The experimental adhesive copolymers showed higher glass transition temperature and rubbery moduli, as well as improved water miscibility compared to the controls. The enhanced properties of the adhesive copolymers indicated that BMPMOB is a promising comonomer for dental restorative materials. PMID:24596134

  8. Nucleic acids encoding modified human immunodeficiency virus type 1 (HIV-1) group M consensus envelope glycoproteins

    DOEpatents

    Haynes, Barton F [Durham, NC; Gao, Feng [Durham, NC; Korber, Bette T [Los Alamos, NM; Hahn, Beatrice H [Birmingham, AL; Shaw, George M [Birmingham, AL; Kothe, Denise [Birmingham, AL; Li, Ying Ying [Hoover, AL; Decker, Julie [Alabaster, AL; Liao, Hua-Xin [Chapel Hill, NC

    2011-12-06

    The present invention relates, in general, to an immunogen and, in particular, to an immunogen for inducing antibodies that neutralizes a wide spectrum of HIV primary isolates and/or to an immunogen that induces a T cell immune response. The invention also relates to a method of inducing anti-HIV antibodies, and/or to a method of inducing a T cell immune response, using such an immunogen. The invention further relates to nucleic acid sequences encoding the present immunogens.

  9. Saxitoxins and okadaic acid group: accumulation and distribution in invertebrate marine vectors from Southern Chile.

    PubMed

    García, Carlos; Pérez, Francisco; Contreras, Cristóbal; Figueroa, Diego; Barriga, Andrés; López-Rivera, Américo; Araneda, Oscar F; Contreras, Héctor R

    2015-01-01

    Harmful algae blooms (HABs) are the main source of marine toxins in the aquatic environment surrounding the austral fjords in Chile. Huichas Island (Aysén) has an history of HABs spanning more than 30 years, but there is limited investigation of the bioaccumulation of marine toxins in the bivalves and gastropods from the Region of Aysén. In this study, bivalves (Mytilus chilenses, Choromytilus chorus, Aulacomya ater, Gari solida, Tagelus dombeii and Venus antiqua) and carnivorous gastropods (Argobuccinum ranelliformes and Concholepas concholepas) were collected from 28 sites. Researchers analysed the accumulation of STX-group toxins using a LC with a derivatisation post column (LC-PCOX), while lipophilic toxins (OA-group, azapiracids, pectenotoxins and yessotoxins) were analysed using LC-MS/MS with electrospray ionisation (+/-) in visceral (hepatopancreas) and non-visceral tissues (mantle, adductor muscle, gills and foot). Levels of STX-group and OA-group toxins varied among individuals from the same site. Among all tissue samples, the highest concentrations of STX-group toxins were noted in the hepatopancreas in V. antiqua (95 ± 0.1 μg STX-eq 100 g(-1)), T. dombeii (148 ± 1.4 μg STX-eq 100 g(-1)) and G. solida (3232 ± 5.2 μg STX-eq 100 g(-1); p < 0.05); in the adductor muscle in M. chilensis (2495 ± 6.4 μg STX-eq 100 g(-1); p < 0.05) and in the foot in C. concholepas (81 ± 0.7 μg STX-eq 100 g(-1)) and T. dombeii (114 ± 1.2 μg STX-eq 100 g(-1)). The highest variability of toxins was detected in G. solida, where high levels of carbamate derivatives were identified (GTXs, neoSTX and STX). In addition to the detected hydrophilic toxins, OA-group toxins were detected (OA and DTX-1) with an average ratio of ≈1:1. The highest levels of OA-group toxins were in the foot of C. concholepas, with levels of 400.3 ± 3.6 μg OA eq kg(-1) (p < 0.05) and with a toxic profile composed of 90% OA. A wide range of OA-group toxins was detected in M. chilensis with a

  10. Synthesis of side chain N,N'-diaminoalkylated derivatives of basic amino acids for application in solid-phase peptide synthesis.

    PubMed

    Pitteloud, Jean-Philippe; Bionda, Nina; Cudic, Predrag

    2013-01-01

    Despite the enormous therapeutic potential, the clinical use of peptides has been limited by their poor bioavailability and low stability under physiological conditions. Hence, efforts have been undertaken to alter peptide structure in ways to improve their pharmacological properties. Inspired by the importance of basic amino acids in biological systems and the remarkable versatility displayed by lysine during the synthesis of complex peptide scaffolds, this chapter describes a simple procedure that enables rapid access to protected N,N'-diaminoalkylated basic amino acid building blocks suitable for standard solid-phase peptide synthesis. This procedure allows preparation of symmetrical, as well as unsymmetrical, dialkylated amino acid derivatives that can be further modified, enhancing their synthetic utility. The suitability of the synthesized branched basic amino acid building blocks for use in standard solid-phase peptide synthesis has been demonstrated by synthesis of an indolicidin analog in which the lysine residue was substituted with its synthetic polyamino derivate. The substitution provided indolicidin analog with increase net positive charge, more ordered secondary structure in biological membranes mimicking conditions, and enhanced antibacterial activity without altering hemolytic activity. Taking into consideration the increasing interest for peptides with unusual structural features due to their improved biological properties, the described synthesis of polyfunctional amino acid building blocks is of particular practical value.

  11. Effect of the Methylation and N-H Acidic Group on the Physicochemical Properties of Imidazolium-Based Ionic Liquids.

    PubMed

    Rodrigues, Ana S M C; Rocha, Marisa A A; Almeida, Hugo F D; Neves, Catarina M S S; Lopes-da-Silva, José A; Freire, Mara G; Coutinho, João A P; Santos, Luís M N B F

    2015-07-16

    This work presents and highlights the differentiation of the physicochemical properties of the [C1Him][NTf2], [C2Him][NTf2], [(1)C1(2)C1Him][NTf2], and [(1)C4(2)C1(3)C1im][NTf2] that is related with the strong bulk interaction potential, which highlights the differentiation on the physicochemical arising from the presence of the acidic group (N-H) as well as the methylation in position 2, C(2), of the imidazolium ring. Densities, viscosities, refractive indices, and surface tensions in a wide range of temperatures, as well as isobaric heat capacities at 298.15 K, for this IL series are presented and discussed. It was found that the volumetric properties are barely affected by the geometric and structural isomerization, following a quite regular trend. A linear correlation between the glass transition temperature, Tg, and the alkyl chain size was found; however, ILs with the acidic N-H group present a significant higher Tg than the [(1)CN-1(3)C1im][NTf2] and [(1)CN(3)CNim][NTf2] series. It was found that the most viscous ILs, ([(1)C1Him][NTf2], [(1)C2Him][NTf2], and [(1)C1(2)C1Him][NTf2]) have an acidic N-H group in the imidazolium ring in agreement with the observed increase of energy barrier of flow. The methylation in position 2, C(2), as well as the N-H acidic group in the imidazolium ring contribute to a significant variation in the cation-anion interactions and their dynamics, which is reflected in their charge distribution and polarizability leading to a significant differentiation of the refractive indices, surface tension, and heat capacities. The observed differentiation of the physicochemical properties of the [(1)C1Him][NTf2], [(1)C2Him][NTf2], [(1)C1(2)C1Him][NTf2], and [(1)C4(2)C1(3)C1im][NTf2] are an indication of the stronger bulk interaction potential, which highlights the effect that arises from the presence of the acidic group (N-H) as well as the methylation in position 2 of the imidazolium ring.

  12. NMR chemical shifts in amino acids: Effects of environments, electric field, and amine group rotation

    SciTech Connect

    Yoon, Young-Gui; Pfrommer, Bernd G.; Louie, Steven G.; Canning, Andrew

    2002-03-03

    The authors present calculations of NMR chemical shifts in crystalline phases of some representative amino acids such as glycine, alanine, and alanyl-alanine. To get an insight on how different environments affect the chemical shifts, they study the transition from the crystalline phase to completely isolated molecules of glycine. In the crystalline limit, the shifts are dominated by intermolecular hydrogen-bonds. In the molecular limit, however, dipole electric field effects dominate the behavior of the chemical shifts. They show that it is necessary to average the chemical shifts in glycine over geometries. Tensor components are analyzed to get the angle dependent proton chemical shifts, which is a more refined characterization method.

  13. Group 11 complexes with amino acid derivatives: Synthesis and antitumoral studies.

    PubMed

    Ortego, Lourdes; Meireles, Margarida; Kasper, Cornelia; Laguna, Antonio; Villacampa, M Dolores; Gimeno, M Concepción

    2016-03-01

    Gold(I), gold(III), silver(I) and copper(I) complexes with modified amino acid esters and phosphine ligands have been prepared in order to test their cytotoxic activity. Two different phosphine fragments, PPh3 and PPh2py (py=pyridine), have been used. The amino acid esters have been modified by introducing an aromatic amine as pyridine that coordinates metal fragments through the nitrogen atom, giving complexes of the type [M(L)(PR3)](+) or [AuCl3(L)] (L=l-valine-N-(4-pyridylcarbonyl) methyl ester (L1), l-alanine-N-(4-pyridylcarbonyl) methyl ester (L2), l-phenylalanine-N-(4-pyridylcarbonyl) methyl-ester) (L3); M=Au(I), Ag(I), Cu(I), PR3=PPh3, PPh2py). The in vitro cytotoxic activity of metal complexes was tested against four tumor human cell lines and one tumor mouse cell line. A metabolic activity test (3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide, MTT) was used and IC50 values were compared with those obtained for cisplatin. Several complexes displayed significant cytotoxic activities. In order to determine whether antiproliferation and cell death are associated with apoptosis, NIH-3T3 cells were exposed to five selected complexes (Annexin V+ FITC, PI) and analyzed by flow cytometry. These experiments showed that the mechanism by which the complexes inhibit cell proliferation inducing cell death in NIH-3T3 cells is mainly apoptotic.

  14. Correlation of secondary-side IGA/SCC degradation of recirculating steam generator tubing with the on-line addition of boric acid

    SciTech Connect

    Partridge, M.J.; Zemitis, W.S.; Gorman, J.A. )

    1992-08-01

    A survey of field data indicates that the on-line addition of boric acid can reduce the rate of intergranular attack and stress corrosion cracking (IGA/SCC) within the hot leg tube support crevices for some PWR steam generators. However, the beneficial effect was not seen at all surveyed plants. 68 refs., 12 tabs., 12 refs.

  15. Fabrication process of intrinsic Josephson junction stacks in Bi2Sr2CaCu2O8+x crystals by double-sided patterning process using dilute hydrochloric acid

    NASA Astrophysics Data System (ADS)

    Kato, Takahiro; Ishida, Hiroki; Suematsu, Hisayuki; Yasui, Kanji; Hamasaki, Katsuyoshi

    2012-07-01

    We have developed a new double-sided patterning (DSP) process that employs dilute acid (pH = 1.65) to fabricate Bi2Sr2CaCu2O8+x (Bi-2212) stacks of intrinsic Josephson junctions. These stacks, which were fabricated from a single crystal of Bi-2212, were surrounded by an acid-treated product. The critical aspect of this process is that the Bi-2212 surrounding the photoresist pattern was converted into a transparent material, BiOCl, which was connected with the Bi-2212 crystal. Consequently, this process provides a simple way to achieve DSP of the surfaces of Bi-2212 crystals. This new DSP process realizes a remarkably improved reproducibility in fabricating Bi-2212 stacks that exhibit good current-voltage characteristics with a large hysteresis and multiple branches at T = 77 K.

  16. Highly Sensitive Thin-Film Field-Effect Transistor Sensor for Ammonia with the DPP-Bithiophene Conjugated Polymer Entailing Thermally Cleavable tert-Butoxy Groups in the Side Chains.

    PubMed

    Yang, Yang; Zhang, Guanxin; Luo, Hewei; Yao, Jingjing; Liu, Zitong; Zhang, Deqing

    2016-02-17

    The sensing and detection of ammonia have received increasing attention in recent years because of the growing emphasis on environmental and health issues. In this paper, we report a thin-film field-effect transistor (FET)-based sensor for ammonia and other amines with remarkable high sensitivity and satisfactory selectivity by employing the DPP-bithiophene conjugated polymer pDPPBu-BT in which tert-butoxycarboxyl groups are incorporated in the side chains. This polymer thin film shows p-type semiconducting property. On the basis of TGA and FT-IR analysis, tert-butoxycarboxyl groups can be transformed into the -COOH ones by eliminating gaseous isobutylene after thermal annealing of pDPPBu-BT thin film at 240 °C. The FET with the thermally treated thin film of pDPPBu-BT displays remarkably sensitive and selective response toward ammonia and volatile amines. This can be attributed to the fact that the elimination of gaseous isobutylene accompanies the formation of nanopores with the thin film, which will facilitate the diffusion and interaction of ammonia and other amines with the semiconducting layer, leading to high sensitivity and fast response for this FET sensor. This FET sensor can detect ammonia down to 10 ppb and the interferences from other volatile analytes except amines can be negligible.

  17. Electron transfer in acetohydroxy acid synthase as a side reaction of catalysis. Implications for the reactivity and partitioning of the carbanion/enamine form of (alpha-hydroxyethyl)thiamin diphosphate in a "nonredox" flavoenzyme.

    PubMed

    Tittmann, Kai; Schröder, Kathrin; Golbik, Ralph; McCourt, Jennifer; Kaplun, Alexander; Duggleby, Ronald G; Barak, Ze'ev; Chipman, David M; Hübner, Gerhard

    2004-07-13

    Acetohydroxy acid synthases (AHAS) are thiamin diphosphate- (ThDP-) and FAD-dependent enzymes that catalyze the first common step of branched-chain amino acid biosynthesis in plants, bacteria, and fungi. Although the flavin cofactor is not chemically involved in the physiological reaction of AHAS, it has been shown to be essential for the structural integrity and activity of the enzyme. Here, we report that the enzyme-bound FAD in AHAS is reduced in the course of catalysis in a side reaction. The reduction of the enzyme-bound flavin during turnover of different substrates under aerobic and anaerobic conditions was characterized by stopped-flow kinetics using the intrinsic FAD absorbance. Reduction of enzyme-bound FAD proceeds with a net rate constant of k' = 0.2 s(-1) in the presence of oxygen and approximately 1 s(-1) under anaerobic conditions. No transient flavin radicals are detectable during the reduction process while time-resolved absorbance spectra are recorded. Reconstitution of the binary enzyme-FAD complex with the chemically synthesized intermediate 2-(hydroxyethyl)-ThDP also results in a reduction of the flavin. These data provide evidence for the first time that the key catalytic intermediate 2-(hydroxyethyl)-ThDP in the carbanionic/enamine form is not only subject to covalent addition of 2-keto acids and an oxygenase side reaction but also transfers electrons to the adjacent FAD in an intramolecular redox reaction yielding 2-acetyl-ThDP and reduced FAD. The detection of the electron transfer supports the idea of a common ancestor of acetohydroxy acid synthase and pyruvate oxidase, a homologous ThDP- and FAD-dependent enzyme that, in contrast to AHASs, catalyzes a reaction that relies on intercofactor electron transfer.

  18. Modifying the OPLS-AA force field to improve hydration free energies for several amino acid side chains using new atomic charges and an off-plane charge model for aromatic residues.

    PubMed

    Xu, Zhitao; Luo, Harry H; Tieleman, D Peter

    2007-02-01

    The hydration free energies of amino acid side chains are an important determinant of processes that involve partitioning between different environments, including protein folding, protein complex formation, and protein-membrane interactions. Several recent papers have shown that calculated hydration free energies for polar and aromatic residues (Trp, His, Tyr, Asn, Gln, Asp, Glu) in several common molecular dynamics force fields differ significantly from experimentally measured values. We have attempted to improve the hydration energies for these residues by modifying the partial charges of the OPLS-AA force field based on natural population analysis of density functional theory calculations. The resulting differences between calculated hydration free energies and experimental results for the seven side chain analogs are less than 0.1 kcal/mol. Simulations of the synthetic Trp-rich peptide Trpzip2 show that the new charges lead to significantly improved geometries for interacting Trp-side chains. We also investigated an off-plane charge model for aromatic rings that more closely mimics their electronic configuration. This model results in an improved free energy of hydration for Trp and a somewhat altered benzene-sodium potential of mean force with a more favorable energy for direct benzene-sodium contact.

  19. Foldamers to nanotubes: influence of amino acid side chains in the hierarchical assembly of α,γ(4)-hybrid peptide helices.

    PubMed

    Jadhav, Sandip V; Misra, Rajkumar; Gopi, Hosahudya N

    2014-12-08

    Supramolecular assembly of various artificially folded 12-helical architectures composed of γ(4) -Val, γ(4) -Leu and γ(4) -Phe residues is investigated. In contrast to the 12-helices composed of γ(4) -Val and γ(4) -Leu residues, the helices with γ(4) -Phe residues displayed unique elongated nanotubular architectures. The elongated nanotube assembly was further explored as a template for biomineralization of silver ions to silver nanowires. A comparative study using an analogous α-peptide helix reveals the importance of the spatial arrangement of aromatic side chains along the helical cylinder in a 12-helix. These results suggested that the proteolytically and structurally stable α,γ(4) -hybrid peptide 12-helices may serve as a new generation of potential templates in the design of functional biomaterials.

  20. Comparison of the utility of the classic model (the Henderson-Hasselbach equation) and the Stewart model (Strong Ion Approach) for the diagnostics of acid-base balance disorders in dogs with right sided heart failure.

    PubMed

    Sławuta, P; Glińska-Suchocka, K

    2012-01-01

    Classically, the acid-base balance (ABB) is described by the Henderson-Hasselbach equation, where the blood pH is a result of a metabolic components--the HCO3(-) concentration and a respiratory component--pCO2. The Stewart model assumes that the proper understanding of the organisms ABB is based on an analysis of: pCO2, Strong Ion difference (SID)--the difference strong cation and anion concentrations in the blood serum, and the Acid total (Atot)--the total concentration of nonvolatile weak acids. Right sided heart failure in dogs causes serious haemodynamic disorders in the form of peripheral stasis leading to formation of transudates in body cavities, which in turn causes ABB respiratory and metabolic disorders. The study was aimed at analysing the ABB parameters with the use of the classic method and the Stewart model in dogs with the right sided heart failure and a comparison of both methods for the purpose of their diagnostic and therapeutic utility. The study was conducted on 10 dogs with diagnosed right sided heart failure. Arterial and venous blood was drawn from the animals. Analysis of pH, pCO2 and HCO3(-) was performed from samples of arterial blood. Concentrations of Na+, K+, Cl(-), P(inorganic), albumins and lactate were determined from venous blood samples and values of Strong Ion difference of Na+, K+ and Cl(-) (SID3), Strong Ion difference of Na+, K+, Cl(-) and lactate (SID4), Atot, Strong Ion difference effective (SIDe) and Strong Ion Gap (SIG4) were calculated. The conclusions are as follows: 1) diagnosis of ABB disorders on the basis of the Stewart model showed metabolic alkalosis in all dogs examined, 2) in cases of circulatory system diseases, methodology based on the Stewart model should be applied for ABB disorder diagnosis, 3) if a diagnosis of ABB disorders is necessary, determination of pH, pCO2 and HCO3(-) as well as concentrations of albumins and P(inorganic) should be determined on a routine basis, 4) for ABB disorder diagnosis, the

  1. The Parmotrema acid test: a look at species delineation in the P. perforatum group 40 y later.

    PubMed

    Lendemer, James C; Allen, Jessica L; Noell, Nastassja

    2015-01-01

    Parmotrema perforatum and its relatives form a morphologically distinctive group of species, most of which are common and endemic to eastern North America. Species delimitation in this ecologically important group was the subject of extensive inquiry before the advent of molecular systematics and computationally intensive niche modeling. As part of a large-scale lichen biodiversity inventory of the Mid-Atlantic Coastal Plain, we used ITS sequence data to examine the utility of characters (morphological, chemical, reproductive, ecological) in circumscribing four species in this group (P. hypoleucinum, P. hypotropum, P. perforatum, P. subrigidum). We found that P. hypoleucinum and P. subrigidum as currently circumscribed are monophyletic and the latter comprises two chemotypes differing in the presence or absence of norstictic acid in addition to alectoronic acid. The sequences of P. hypotropum and P. perforatum, which are chemically identical species and differ only in reproductive mode, were intermixed in a single, well-supported clade. The two chemotypes of P. subrigidum are partially allopatric and their sequences are >99% identical. Nonetheless, niche modeling suggests they occupy significantly different ecological niches. These results provide a new perspective on much-debated questions on species circumscription in lichens and suggest new avenues for genetic, ecological and systematic research.

  2. Phylogenetic group- and species-specific oligonucleotide probes for single-cell detection of lactic acid bacteria in oral biofilms

    PubMed Central

    2011-01-01

    Background The purpose of this study was to design and evaluate fluorescent in situ hybridization (FISH) probes for the single-cell detection and enumeration of lactic acid bacteria, in particular organisms belonging to the major phylogenetic groups and species of oral lactobacilli and to Abiotrophia/Granulicatella. Results As lactobacilli are known for notorious resistance to probe penetration, probe-specific assay protocols were experimentally developed to provide maximum cell wall permeability, probe accessibility, hybridization stringency, and fluorescence intensity. The new assays were then applied in a pilot study to three biofilm samples harvested from variably demineralized bovine enamel discs that had been carried in situ for 10 days by different volunteers. Best probe penetration and fluorescent labeling of reference strains were obtained after combined lysozyme and achromopeptidase treatment followed by exposure to lipase. Hybridization stringency had to be established strictly for each probe. Thereafter all probes showed the expected specificity with reference strains and labeled the anticipated morphotypes in dental plaques. Applied to in situ grown biofilms the set of probes detected only Lactobacillus fermentum and bacteria of the Lactobacillus casei group. The most cariogenic biofilm contained two orders of magnitude higher L. fermentum cell numbers than the other biofilms. Abiotrophia/Granulicatella and streptococci from the mitis group were found in all samples at high levels, whereas Streptococcus mutans was detected in only one sample in very low numbers. Conclusions Application of these new group- and species-specific FISH probes to oral biofilm-forming lactic acid bacteria will allow a clearer understanding of the supragingival biome, its spatial architecture and of structure-function relationships implicated during plaque homeostasis and caries development. The probes should prove of value far beyond the field of oral microbiology, as many of

  3. Acidity of the amidoxime functional group in aqueous solution. A combined experimental and computational study

    SciTech Connect

    Mehio, Nada; Lashely, Mark A.; Nugent, Joseph W.; Tucker, Lyndsay; Correia, Bruna; Do-Thanh, Chi-Linh; Dai, Sheng; Hancock, Robert D.; Bryantsev, Vyacheslav S.

    2015-01-26

    Poly(acrylamidoxime) adsorbents are often invoked in discussions of mining uranium from seawater. It has been demonstrated repeatedly in the literature that the success of these materials is due to the amidoxime functional group. While the amidoxime-uranyl chelation mode has been established, a number of essential binding constants remain unclear. This is largely due to the wide range of conflicting pKa values that have been reported for the amidoxime functional group in the literature. To resolve this existing controversy we investigated the pKa values of the amidoxime functional group using a combination of experimental and computational methods. Experimentally, we used spectroscopic titrations to measure the pKa values of representative amidoximes, acetamidoxime and benzamidoxime. Computationally, we report on the performance of several protocols for predicting the pKa values of aqueous oxoacids. Calculations carried out at the MP2 or M06-2X levels of theory combined with solvent effects calculated using the SMD model provide the best overall performance with a mean absolute error of 0.33 pKa units and 0.35 pKa units, respectively, and a root mean square deviation of 0.46 pKa units and 0.45 pKa units, respectively. Finally, we employ our two best methods to predict the pKa values of promising, uncharacterized amidoxime ligands. Hence, our study provides a convenient means for screening suitable amidoxime monomers for future generations of poly(acrylamidoxime) adsorbents used to mine uranium from seawater.

  4. Acidity of the amidoxime functional group in aqueous solution. A combined experimental and computational study

    DOE PAGES

    Mehio, Nada; Lashely, Mark A.; Nugent, Joseph W.; ...

    2015-01-26

    Poly(acrylamidoxime) adsorbents are often invoked in discussions of mining uranium from seawater. It has been demonstrated repeatedly in the literature that the success of these materials is due to the amidoxime functional group. While the amidoxime-uranyl chelation mode has been established, a number of essential binding constants remain unclear. This is largely due to the wide range of conflicting pKa values that have been reported for the amidoxime functional group in the literature. To resolve this existing controversy we investigated the pKa values of the amidoxime functional group using a combination of experimental and computational methods. Experimentally, we used spectroscopicmore » titrations to measure the pKa values of representative amidoximes, acetamidoxime and benzamidoxime. Computationally, we report on the performance of several protocols for predicting the pKa values of aqueous oxoacids. Calculations carried out at the MP2 or M06-2X levels of theory combined with solvent effects calculated using the SMD model provide the best overall performance with a mean absolute error of 0.33 pKa units and 0.35 pKa units, respectively, and a root mean square deviation of 0.46 pKa units and 0.45 pKa units, respectively. Finally, we employ our two best methods to predict the pKa values of promising, uncharacterized amidoxime ligands. Hence, our study provides a convenient means for screening suitable amidoxime monomers for future generations of poly(acrylamidoxime) adsorbents used to mine uranium from seawater.« less

  5. Pressure-dependent studies on hydration of the C-H group in formic acid

    NASA Astrophysics Data System (ADS)

    Chang, Hai-Chou; Jiang, Jyh-Chiang; Chao, Ming-Chi; Lin, Ming-Shan; Lin, Sheng Hsien; Chen, Hsin-Yen; Hsueh, Hung-Chung

    2001-11-01

    The infrared spectroscopic profiles of HCOOD/D2O mixtures were measured as a function of pressure and concentration. The C-H bond of HCOOD shortens as the pressure is elevated, while the increase in C-H bond length upon diluting HCOOD with D2O was observed. Based on the experimental results, the shift in frequency of C-H stretching band is concluded to relate to the mechanism of the hydration of the C-H group and the water structure in the vicinity of the C-H group. The pressure-dependent results can be attributed to the strengthening of C-H---O electrostatic/dispersion interaction upon increasing pressure. The observations are in accord with ab initio calculation forecasting a blueshift of the C-H stretching mode via C-H---O interaction in HCOOD-water/(HCOOD)2-(D2O) complexes relative to the noninteracting monomer/dimer. Hydrogen-bonding nonadditivity and the size of water clusters are suggested to be responsible to cause the redshift in C-H stretching mode upon dilution HCOOD with D2O.

  6. Emotional Side Effects

    MedlinePlus

    ... En Español Category Treatment & Support Treatments and Side Effects Coping with Cancer In this section you can ... Finding and Paying for Treatment Treatments and Side Effects Survivorship: During and After Treatment Caregivers and Family ...

  7. Side Effects (Management)

    MedlinePlus

    ... Cancer is Treated Side Effects Dating, Sex, and Reproduction Advanced Cancer For Children For Teens For Young ... Cancer is Treated Side Effects Dating, Sex, and Reproduction Advanced Cancer For Children For Teens For Young ...

  8. Guanidinium groups act as general-acid catalysts in phosphoryl transfer reactions: a two-proton inventory on a model system.

    PubMed

    Piatek, Anna M; Gray, Mark; Anslyn, Eric V

    2004-08-18

    Cleavage/transesterification of phosphodiesters is catalyzed by various acidic groups in solution and with enzymes. General-acid catalysts can transfer protons to the developing phosphorane intermediate, resulting in a monoprotic-monoanionic intermediate, giving the so-called "triester mechanism". Using a proton inventory on a model compound (1) possessing an intramolecular hydrogen bond between a phosphodiester and a guanidinium group, we find that two protons move in the rate-determining step for cleavage/transesterification. In contrast, HPNP shows a single-proton inventory and is a substrate well accepted to react with the movement of only one proton at the transition state. We therefore propose a mechanism for 1 that involves general-acid catalysis by the guanidinium group. This leads one to conclude that other, more acidic groups, such as ammonium and imidazolium, would also act as general-acid catalysts.

  9. Investigation of Humidity Dependent Surface Morphology and Proton Conduction in Multi-Acid Side Chain Membranes by Conductive Probe Atomic Force Microscopy.

    PubMed

    Economou, Nicholas J; Barnes, Austin M; Wheat, Andrew J; Schaberg, Mark S; Hamrock, Steven J; Buratto, Steven K

    2015-11-05

    In this report, we employ phase-contrast tapping mode and conductive probe atomic force microscopy (cp-AFM) as tools to investigate the nanoscale morphology and proton conductance of a 3M perfluoro-imide acid (PFIA) membrane (625 EW) over a large range of relative humidity (3-95% RH). As a point of comparison, we also investigate 3M perfluorosulfonic acid (PFSA) (825 EW) and Nafion 212. With AFM, we assess the membrane's water retention and mechanical stability at low RH and high RH, respectively. Cp-AFM allows us to spatially resolve the hydrophilic and electrochemically active domains under a similar set of conditions and observe directly the ties between membrane morphology and proton conductance. From our data, we are able to correlate the improved water retention indicated by the size of the hydrophilic domains with the proton conductance in the PFIA membrane at elevated temperature and compare the result with that observed for the PFSA and Nafion. At high RH conditions, we see evidence of a nearly continuous hydrophilic phase, which indicates a high degree of swelling.

  10. Prediction of intramuscular fat content and major fatty acid groups of lamb M. longissimus lumborum using Raman spectroscopy.

    PubMed

    Fowler, Stephanie M; Ponnampalam, Eric N; Schmidt, Heinar; Wynn, Peter; Hopkins, David L

    2015-12-01

    A hand held Raman spectroscopic device was used to predict intramuscular fat (IMF) levels and the major fatty acid (FA) groups of fresh intact ovine M. longissimus lumborum (LL). IMF levels were determined using the Soxhlet method, while FA analysis was conducted using a rapid (KOH in water, methanol and sulphuric acid in water) extraction procedure. IMF levels and FA values were regressed against Raman spectra using partial least squares regression and against each other using linear regression. The results indicate that there is potential to predict PUFA (R(2)=0.93) and MUFA (R(2)=0.54) as well as SFA values that had been adjusted for IMF content (R(2)=0.54). However, this potential was significantly reduced when correlations between predicted and observed values were determined by cross validation (R(2)cv=0.21-0.00). Overall, the prediction of major FA groups using Raman spectra was more precise (relative reductions in error of 0.3-40.8%) compared to the null models.

  11. Vaccines containing de-N-acetyl sialic acid elicit antibodies protective against Neisseria meningitidis group B and C1

    PubMed Central

    Moe, Gregory R.; Bhandari, Tamara S.; Flitter, Becca A.

    2009-01-01

    Murine monoclonal antibodies (mAbs) that were produced by immunization with a vaccine containing the N-propionyl derivative of Neisseria meningitidis group B (MenB) capsular polysaccharide (NPr MBPS) mediate protective responses against MenB but were not reactive with unmodified MBPS or chemically identical human polysialic acid (PSA). Recently, we showed that some of the mAbs were reactive with MBPS derivatives that contain de-N-acetyl sialic acid residues (Moe et al. 2005, Infect Immun 73:2123–2128). In this study we evaluated the immunogenicity of de-N-acetyl sialic acid-containing derivatives of PSA (de-N-acetyl PSA) in mice. Four de-N-acetyl PSA antigens were prepared and conjugated to tetanus toxoid, including completely de-N-acetylated PSA. All of the vaccines elicited anti-de-N-acetyl PSA responses (titers ≥1:10,000) but only vaccines enriched for non-reducing end de-N-acetyl residues by treatment with exoneuraminidase or complete de-N-acetylation elicited high titers against the homologous antigen. Also, non-reducing end de-N-acetyl residue-enriched vaccines elicited IgM and IgG antibodies of all subclasses that could bind to MenB. The results suggest that the zwitterionic characteristic of neuraminic acid, particularly at the non-reducing end may be important for processing and presentation mechanisms that stimulate T cells. Antibodies elicited by all four vaccines were able to activate deposition of human complement proteins and passively protect against challenge by MenB in the infant rat model of meningococcal bacteremia. Some vaccine antisera mediated bactericidal activity against a MenC strain with human complement. Thus, de-N-acetyl PSA antigens are immunogenic and elicit antibodies that can be protective against MenB and C strains. PMID:19414816

  12. The nature of peptide interactions with acid end-group PLGAs and facile aqueous-based microencapsulation of therapeutic peptides

    PubMed Central

    Sophocleous, Andreas M.; Desai, Kashappa-Goud H.; Mazzara, J. Maxwell; Tong, Ling; Cheng, Ji-Xin; Olsen, Karl F.; Schwendeman, Steven P.

    2013-01-01

    An important poorly understood phenomenon in controlled-release depots involves the strong interaction between common cationic peptides and low Mw free acid end-group poly(lactic-co-glycolic acids) (PLGAs) used to achieve continuous peptide release kinetics. The kinetics of peptide sorption to PLGA was examined by incubating peptide solutions of 0.2-4 mM octreotide or leuprolide acetate salts in 0.1 M HEPES buffer, pH 7.4, with polymer particles or films at 4-37 °C for 24 h. The extent of absorption/loading of peptides in PLGA particles/films was assayed by two-phase extraction and amino acid analysis. Confocal Raman microspectroscopy and stimulated Raman scattering (SRS) and laser scanning confocal imaging techniques were used to examine peptide penetration in the polymer phase. The release of sorbed peptide from leuprolide-PLGA particles was evaluated both in vitro (PBST + 0.02% sodium azide, 37 °C) and in vivo (male Sprague-Dawley rats). We found that when the PLGA-COOH chains are sufficiently mobilized, therapeutic peptides not only bind at the surface, a common belief to date, but can also internalized and distributed throughout the polymer phase at physiological temperature forming a salt with low-molecular weight PLGA-COOH. Importantly, absorption of leuprolide into low MW PLGA-COOH particles yielded ~17 wt% leuprolide loading in the polymer (i.e., ~70% of PLGA-COOH acids occupied), and the absorbed peptide was released from the polymer for > 2 weeks in a controlled fashion in vitro and as indicated by sustained testosterone suppression in male Sprague-Dawley rats. This new approach, which bypasses the traditional encapsulation method and associated production cost, opens up the potential for facile production of low-cost controlled-release injectable depots for leuprolide and related peptides. PMID:24021356

  13. Group X Secreted Phospholipase A2 Releases ω3 Polyunsaturated Fatty Acids, Suppresses Colitis, and Promotes Sperm Fertility*

    PubMed Central

    Murase, Remi; Sato, Hiroyasu; Yamamoto, Kei; Ushida, Ayako; Nishito, Yasumasa; Ikeda, Kazutaka; Kobayashi, Tetsuyuki; Yamamoto, Toshinori; Taketomi, Yoshitaka; Murakami, Makoto

    2016-01-01

    Within the secreted phospholipase A2 (sPLA2) family, group X sPLA2 (sPLA2-X) has the highest capacity to hydrolyze cellular membranes and has long been thought to promote inflammation by releasing arachidonic acid, a precursor of pro-inflammatory eicosanoids. Unexpectedly, we found that transgenic mice globally overexpressing human sPLA2-X (PLA2G10-Tg) displayed striking immunosuppressive and lean phenotypes with lymphopenia and increased M2-like macrophages, accompanied by marked elevation of free ω3 polyunsaturated fatty acids (PUFAs) and their metabolites. Studies using Pla2g10-deficient mice revealed that endogenous sPLA2-X, which is highly expressed in the colon epithelium and spermatozoa, mobilized ω3 PUFAs or their metabolites to protect against dextran sulfate-induced colitis and to promote fertilization, respectively. In colitis, sPLA2-X deficiency increased colorectal expression of Th17 cytokines, and ω3 PUFAs attenuated their production by lamina propria cells partly through the fatty acid receptor GPR120. In comparison, cytosolic phospholipase A2 (cPLA2α) protects from colitis by mobilizing ω6 arachidonic acid metabolites, including prostaglandin E2. Thus, our results underscore a previously unrecognized role of sPLA2-X as an ω3 PUFA mobilizer in vivo, segregated mobilization of ω3 and ω6 PUFA metabolites by sPLA2-X and cPLA2α, respectively, in protection against colitis, and the novel role of a particular sPLA2-X-driven PUFA in fertilization. PMID:26828067

  14. Group X Secreted Phospholipase A2 Releases ω3 Polyunsaturated Fatty Acids, Suppresses Colitis, and Promotes Sperm Fertility.

    PubMed

    Murase, Remi; Sato, Hiroyasu; Yamamoto, Kei; Ushida, Ayako; Nishito, Yasumasa; Ikeda, Kazutaka; Kobayashi, Tetsuyuki; Yamamoto, Toshinori; Taketomi, Yoshitaka; Murakami, Makoto

    2016-03-25

    Within the secreted phospholipase A2(sPLA2) family, group X sPLA2(sPLA2-X) has the highest capacity to hydrolyze cellular membranes and has long been thought to promote inflammation by releasing arachidonic acid, a precursor of pro-inflammatory eicosanoids. Unexpectedly, we found that transgenic mice globally overexpressing human sPLA2-X (PLA2G10-Tg) displayed striking immunosuppressive and lean phenotypes with lymphopenia and increased M2-like macrophages, accompanied by marked elevation of free ω3 polyunsaturated fatty acids (PUFAs) and their metabolites. Studies usingPla2g10-deficient mice revealed that endogenous sPLA2-X, which is highly expressed in the colon epithelium and spermatozoa, mobilized ω3 PUFAs or their metabolites to protect against dextran sulfate-induced colitis and to promote fertilization, respectively. In colitis, sPLA2-X deficiency increased colorectal expression of Th17 cytokines, and ω3 PUFAs attenuated their production by lamina propria cells partly through the fatty acid receptor GPR120. In comparison, cytosolic phospholipase A2(cPLA2α) protects from colitis by mobilizing ω6 arachidonic acid metabolites, including prostaglandin E2 Thus, our results underscore a previously unrecognized role of sPLA2-X as an ω3 PUFA mobilizerin vivo, segregated mobilization of ω3 and ω6 PUFA metabolites by sPLA2-X and cPLA2α, respectively, in protection against colitis, and the novel role of a particular sPLA2-X-driven PUFA in fertilization.

  15. Quantification of glycated N-terminal peptide of hemoglobin using derivatization for multiple functional groups of amino acids followed by liquid chromatography/tandem mass spectrometry.

    PubMed

    Sakaguchi, Yohei; Kinumi, Tomoya; Yamazaki, Taichi; Takatsu, Akiko

    2016-02-01

    A novel method of amino acid analysis using derivatization of multiple functional groups (amino, carboxyl, and phenolic hydroxyl groups) was applied to measure glycated amino acids in order to quantify glycated peptides and evaluate the degree of glycation of peptide. Amino and carboxyl groups of amino acids were derivatized with 1-bromobutane so that the hydrophobicities and basicities of the amino acids, including glycated amino acids, were improved. These derivatized amino acids could be detected with high sensitivity using LC-MS/MS. In this study, 1-deoxyfructosyl-VHLTPE and VHLTPE, which are N-terminal peptides of the β-chains of hemoglobin, were selected as target compounds. After reducing the peptide sample solution with sodium borohydride, the obtained peptides were hydrolyzed with hydrochloric acid. The released amino acids were then derivatized with 1-bromobutane and analyzed with LC-MS/MS. The derivatized amino acids, including glycated amino acids, could be separated using an octadecyl silylated silica column and good sharp peaks were detected. We show a confirmatory experiment that the proposed method can be applied to evaluate the degree of glycation of peptides, using mixtures of glycated and non-glycated peptide.

  16. Control of the Position of Oxygen Delivery in Soybean Lipoxygenase-1 by Amino Acid Side Chains within a Gas Migration Channel.

    PubMed

    Collazo, Lara; Klinman, Judith P

    2016-04-22

    Understanding gas migration pathways is critical to unraveling structure-function relationships in enzymes that process gaseous substrates such as O2, H2, and N2 This work investigates the role of a defined pathway for O2 in regulating the peroxidation of linoleic acid by soybean lipoxygenase 1. Computational and mutagenesis studies provide strong support for a dominant delivery channel that shuttles molecular oxygen to a specific region of the active site, thereby ensuring the regio- and stereospecificity of product. Analysis of reaction kinetics and product distribution in channel mutants also reveals a plasticity to the gas migration pathway. The findings show that a single site mutation (I553W) limits oxygen accessibility to the active site, greatly increasing the fraction of substrate that reacts with oxygen free in solution. They also show how a neighboring site mutation (L496W) can result in a redirection of oxygen toward an alternate position of the substrate, changing the regio- and stereospecificity of peroxidation. The present data indicate that modest changes in a protein scaffold may modulate the access of small gaseous molecules to enzyme-bound substrates.

  17. Natural and non-natural amino-acid side-chain substitutions: affinity and diffraction studies of meditope–Fab complexes

    PubMed Central

    Bzymek, Krzysztof P.; Avery, Kendra A.; Ma, Yuelong; Horne, David A.; Williams, John C.

    2016-01-01

    Herein, multiple crystal structures of meditope peptide derivatives incorporating natural and unnatural amino acids bound to the cetuximab Fab domain are presented. The affinity of each derivative was determined by surface plasmon resonance and correlated to the atomic structure. Overall, it was observed that the hydrophobic residues in the meditope peptide, Phe3, Leu5 and Leu10, could accommodate a number of moderate substitutions, but these invariably reduced the overall affinity and half-life of the interaction. In one case, the substitution of Phe3 by histidine led to a change in the rotamer conformation, in which the imidazole ring flipped to a solvent-exposed position. Based on this observation, Phe3 was substituted by diphenylalanine and it was found that the phenyl rings in this variant mimic the superposition of the Phe3 and His3 structures, producing a moderate increase, of 1.4-fold, in the half-life of the complex. In addition, it was observed that substitution of Leu5 by tyrosine and glutamate strongly reduced the affinity, whereas the substitution of Leu5 by diphenyl­alanine moderately reduced the half-life (by approximately fivefold). Finally, it was observed that substitution of Arg8 and Arg9 by citrulline dramatically reduced the overall affinity, presumably owing to lost electrostatic interactions. Taken together, these studies provide insight into the meditope–cetuximab interaction at the atomic level. PMID:27834791

  18. Effects of crystalline structures and surface functional groups on the adsorption of haloacetic acids by inorganic materials.

    PubMed

    Punyapalakul, Patiparn; Soonglerdsongpha, Suwat; Kanlayaprasit, Chutima; Ngamcharussrivichai, Chawalit; Khaodhiar, Sutha

    2009-11-15

    The effects of the crystalline structure and surface functional groups of porous inorganic materials on the adsorption of dichloroacetic acid (DCAA) were evaluated by using hexagonal mesoporous silicates (HMS), two surface functional group (3-aminopropyltriethoxy- and 3-mercaptopropyl-) modified HMSs, faujasite Y zeolite and activated alumina as adsorbents, and compared with powdered activated carbon (PAC). Selective adsorption of HAA(5) group was studied by comparing single and multiple-solute solution, including effect of common electrolytes in tap water. Adsorption capacities were significantly affected by the crystalline structure. Hydrogen bonding is suggested to be the most important attractive force. Decreasing the pH lower than the pH(zpc) increased the DCAA adsorption capacities of these adsorbents due to electrostatic interaction and hydrogen bonding caused by protonation of the hydronium ion. Adsorption capacities of HAA(5) on HMS did not relate to molecular structure of HAA(5). Common electrolytes did not affect the adsorption capacities and selectivity of HMS for HAA5, while they affected those of PAC.

  19. Anhydrous proton-conducting electrolyte membranes based on hyperbranched polymer with phosphonic acid groups for high-temperature fuel cells

    NASA Astrophysics Data System (ADS)

    Itoh, Takahito; Hirai, Keita; Tamura, Masashi; Uno, Takahiro; Kubo, Masataka; Aihara, Yuichi

    The two different molecular weight hyperbranched polymers (HBP(L)-PA-Ac and HBP(H)-PA-Ac) with both phosphonic acid group as a functional group and acryloyl group as a cross-linker at the chain ends were successfully synthesized as a new thermally stable proton-conducting electrolyte. The cross-linked electrolyte membranes (CL-HBP-PA) were prepared by their thermal polymerizations using benzoyl peroxide and their ionic conductivities under dry condition and thermal properties were investigated. The ionic conductivities of the low molecular weight CL-HBP(L)-PA membrane and the high molecular weight CL-HBP(H)-PA membrane were found to be 1.2 × 10 -5 and 2.6 × 10 -6 S cm -1, respectively, at 150 °C under dry condition, and showed the Vogel-Tamman-Fulcher (VTF) type temperature dependence. Both membranes were thermally stable up to 300 °C, and they had suitable thermal stability as electrolyte membranes for the high-temperature fuel cells under dry condition. Fuel cell measurements using a single membrane electrode assembly cell with both cross-linked membranes were successfully performed.

  20. [Degradation of L-phenylalanine and of aromatic carboxylic acids by chloridazon-degrading bacteria. Combination of side chain degradation and dioxygenase pathway].

    PubMed

    Wegst, W; Lingens, F

    1981-09-01

    Strain N of Chloridazon-degrading bacteria degrades phenylalanine via cis-2,3-dihydro-2,3-dihydroxyphenylalanine,2,3-dihydroxyphenylalanine aspartate and 4-hydroxy-2-oxovalerate [Hoppe-Seyler's Z. Physiol. Chem. 360, 957--969, (1979); Biochem. J. 194, 679--684 (1981)]. cis-2,3-Dihydro-2,3-dihydroxyphenylalanine and 2,3-dihydroxyphenylalanine as well as phenylpyruvate, cis-2,3-dihydro-2,3-dihydroxyphenylpyruvate, 2,3-dihydroxyphenylpyruvate, cis-2,3-dihydro-2,3-dihydroxyphenylacetate, 2,3-dihydroxyphenylacetate and 2,3-dihydroxybenzaldehyde are detectable in the medium of strain E during growth on phenylalanine. Incubation with phenylacetate, 3-phenylpropionate or 4-phenylbutyrate leads to the accumulation of the corresponding cis-2,3-dihydro-2,3-dihydroxyphenyl derivatives. These compounds are transformed with dihydrodiol dehydrogenase to 2,3-dihydroxyphenylacetate, 3-(2,3-dihydroxyphenyl)propionate and 4-(2,3-dihydroxyphenyl)-butyrate, 3-(2,3-dihydroxyphenyl)propionate is attacked by a catechol 2,3-dioxygenase and the meta-cleavage product is again cleaved by a hydrolase yielding succinate. In a similar reaction sequence the degradation of 4-phenylbutyrate leads to the formation of glutarate. From the growth medium of strain E on phenylacetate also small amounts of 2-, 3- and 4-hydroxyphenylacetate were isolated. Resting cells were shown to metabolize 3- and 4-hydroxyphenylacetate via homogentisate and 3,4-dihydroxyphenylacetate. In the culture medium of strain K2AP benzoate could be detected. Pathways for the degradation of phenylalanine and aromatic carboxylic acids in chloridazon degrading bacteria are proposed.

  1. Functionalisation of mesoporous silica gel with 2-[(phosphonomethyl)-amino]acetic acid functional groups. Characterisation and application

    NASA Astrophysics Data System (ADS)

    Caldarola, Dario; Mitev, Dimitar P.; Marlin, Lucile; Nesterenko, Ekaterina P.; Paull, Brett; Onida, Barbara; Bruzzoniti, Maria Concetta; Carlo, Rosa Maria De; Sarzanini, Corrado; Nesterenko, Pavel N.

    2014-01-01

    A new complexing adsorbent was prepared by chemical modification of mesoporous silica Kieselgel 60 (dp = 37-63 μm, average pore size 6 nm, specific surface area 425 m2 g-1) with 3-glycidoxypropyltrimethoxysilane and 2-[(phosphonomethyl)amino]acetic acid (PMA), commonly known as glyphosate. The prepared adsorbent was fully characterised using elemental analysis, thermal gravimetric analysis (TGA), acid-base potentiometric titration, Fourier Transform Infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption isotherms at 77 K (BET), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). The concentration of bonded PMA groups calculated from the nitrogen content was 0.38 mmol per gram. The adsorption of transition metal ions on PMA functionalised silica (HEPMAS) was studied from aqueous solutions having different pH and the following selectivity was established, Zn(II) < Co(II) < Cd(II) < Mn(II) < Ni(II) < Cu(II). The calculated values of distribution coefficients D for the adsorption of ecotoxic metal ions on HEPMAS are 5.0 × 104, 4.9 × 105 and 2.6 × 104 for Zn(II), Pb(II) and Cd(II), respectively.

  2. Evidence for an initiation of the methanol-to-olefin process by reactive surface methoxy groups on acidic zeolite catalysts.

    PubMed

    Wang, Wei; Buchholz, Andreas; Seiler, Michael; Hunger, Michael

    2003-12-10

    Recent progress reveals that, in the methanol-to-olefin (MTO) process on acidic zeolites, the conversion of an equilibrium mixture of methanol and DME is dominated by a "hydrocarbon pool" mechanism. However, the initial C-C bond formation, that is, the chemistry during the kinetic "induction period" leading to the reactive hydrocarbon pool, still remains unclear. With the application of a stopped-flow protocol, in the present work, pure surface methoxy groups [SiO(CH(3))Al] were prepared on various acidic zeolite catalysts (H-Y, H-ZSM-5, H-SAPO-34) at temperatures lower than 473 K, and the further reaction of these methoxy species was investigated by in situ (13)C MAS NMR spectroscopy. By using toluene and cyclohexane as probe molecules which are possibly involved in the MTO process, we show the high reactivity of surface methoxy species. Most importantly, the formation of hydrocarbons from pure methoxy species alone is demonstrated for the first time. It was found that (i) surface methoxy species react at room temperature with water to methanol, indicating the occurrence of a chemical equilibrium between these species at low temperatures. In the presence of aromatics and alkanes, (ii) the reactivity of surface methoxy groups allows a methylation of these organic compounds at reaction temperatures of ca. 433 and 493 K, respectively. In the absence of water and other organic species, that is, under flow conditions and on partially methylated catalysts, (iii) a conversion of pure methoxy groups alone to hydrocarbons was observed at temperatures of T >/= 523 K. This finding indicates a possible formation of the first hydrocarbons during the kinetic induction period of the MTO process via the conversion of pure surface methoxy species (case iii). After the first hydrocarbons are formed, or in the presence of a small amount of organic impurities, surface methoxy groups contribute to a further methylation of these organic compounds (case ii), leading to the formation of

  3. Seq2Logo: a method for construction and visualization of amino acid binding motifs and sequence profiles including sequence weighting, pseudo counts and two-sided representation of amino acid enrichment and depletion

    PubMed Central

    Thomsen, Martin Christen Frølund; Nielsen, Morten

    2012-01-01

    Seq2Logo is a web-based sequence logo generator. Sequence logos are a graphical representation of the information content stored in a multiple sequence alignment (MSA) and provide a compact and highly intuitive representation of the position-specific amino acid composition of binding motifs, active sites, etc. in biological sequences. Accurate generation of sequence logos is often compromised by sequence redundancy and low number of observations. Moreover, most methods available for sequence logo generation focus on displaying the position-specific enrichment of amino acids, discarding the equally valuable information related to amino acid depletion. Seq2logo aims at resolving these issues allowing the user to include sequence weighting to correct for data redundancy, pseudo counts to correct for low number of observations and different logotype representations each capturing different aspects related to amino acid enrichment and depletion. Besides allowing input in the format of peptides and MSA, Seq2Logo accepts input as Blast sequence profiles, providing easy access for non-expert end-users to characterize and identify functionally conserved/variable amino acids in any given protein of interest. The output from the server is a sequence logo and a PSSM. Seq2Logo is available at http://www.cbs.dtu.dk/biotools/Seq2Logo (14 May 2012, date last accessed). PMID:22638583

  4. Seq2Logo: a method for construction and visualization of amino acid binding motifs and sequence profiles including sequence weighting, pseudo counts and two-sided representation of amino acid enrichment and depletion.

    PubMed

    Thomsen, Martin Christen Frølund; Nielsen, Morten

    2012-07-01

    Seq2Logo is a web-based sequence logo generator. Sequence logos are a graphical representation of the information content stored in a multiple sequence alignment (MSA) and provide a compact and highly intuitive representation of the position-specific amino acid composition of binding motifs, active sites, etc. in biological sequences. Accurate generation of sequence logos is often compromised by sequence redundancy and low number of observations. Moreover, most methods available for sequence logo generation focus on displaying the position-specific enrichment of amino acids, discarding the equally valuable information related to amino acid depletion. Seq2logo aims at resolving these issues allowing the user to include sequence weighting to correct for data redundancy, pseudo counts to correct for low number of observations and different logotype representations each capturing different aspects related to amino acid enrichment and depletion. Besides allowing input in the format of peptides and MSA, Seq2Logo accepts input as Blast sequence profiles, providing easy access for non-expert end-users to characterize and identify functionally conserved/variable amino acids in any given protein of interest. The output from the server is a sequence logo and a PSSM. Seq2Logo is available at http://www.cbs.dtu.dk/biotools/Seq2Logo (14 May 2012, date last accessed).

  5. Assessment of the hydrolysis process for the determination of okadaic acid-group toxin ester: presence of okadaic acid 7-O-acyl-ester derivates in Spanish shellfish.

    PubMed

    Villar-González, A; Rodríguez-Velasco, M L; Ben-Gigirey, B; Yasumoto, T; Botana, L M

    2008-04-01

    The contamination of different types of shellfish by okadaic acid (OA)-group toxin esters is an important problem that presents serious risk for human health. During previous investigations carried out in our laboratory by liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS), the occurrence of a high percentage of esters in relation to the total OA equivalents has been observed in several shellfish species. The determination of these kinds of toxins using LC/MS or other chemical methods requires a hydrolysis step in order to convert the sterified compounds into the parent toxins, OA, dinophysistoxins-1 (DTX-1) and dinophysistoxins-2 (DTX-2). Most of the hydrolysis procedures are based on an alkaline hydrolysis reaction. However, despite hydrolysis being a critical step within the analysis, it has not been studied in depth up to now. The present paper reports the results obtained after evaluating the hydrolysis process of an esterified form of OA by using a standard of 7-O-acyl ester with palmitoyl as the fatty acid (palOA). Investigations were focused on checking the effectiveness of the hydrolysis for palOA using methanol as solvent standard and matrices matched standards. From the results obtained, no matrix influence on the hydrolysis process was observed and the quantity of palOA converted into OA was always above 80%. The analyses of different Spanish shellfish samples showed percentages of palOA in relation to the total OA esters ranging from 27% to 90%, depending on the shellfish specie.

  6. SKELETAL MUSCLE GROUP VIA PHOSPHOLIPASE A2 (iPLA2β): EXPRESSION AND ROLE IN FATTY ACID OXIDATION†

    PubMed Central

    Carper, Michael J.; Zhang, Sheng; Turk, John; Ramanadham, Sasanka

    2009-01-01

    Among the phospholipases A2 (PLA2s) are the Group VI Ca2+-independent PLA2s (iPLA2s) and expression of multiple transcripts of iPLA2 in skeletal muscle has been reported. In the present study, phospholipase activity and sequential ATP and calmodulin affinity column chromatography analyses reveal that skeletal muscle iPLA2 exhibits properties characteristic of the iPLA2β isoform. The phospholipase activity of iPLA2β has been demonstrated to participate in signal transduction, cell proliferation, and apoptosis. We also report here that skeletal muscle from iPLA2β-null mice, relative to wild type muscle, exhibits a reduced capacity to oxidize palmitate but not palmitoyl-CoA or acetyl-CoA in the absence of changes in fatty acid transporters CD36 and CPT1 or β-hydroxyacyl-CoA dehydrogenase activity. Recently, purified iPLA2β was demonstrated to manifest a thioesterase activity which catalyzes hydrolysis of fatty acyl-CoAs. The liberated CoA-SH facilitates fatty acid transport into the mitochondria. In this regard, we find that fractions eluted from the ATP column and containing iPLA2β phospholipase activity also contained acyl-CoA thioesterase activity that was inhibited by the bromoenol lactone (BEL) suicide inhibitor of iPLA2β. We further find that acyl-CoA thioesterase activity in skeletal muscle preparations from iPLA2β-null mice is significantly reduced, relative to WT activity. These findings suggest that the absence of acyl-CoA thioesterase activity of iPLA2β can lead to reduced fatty acyl-CoA generation and impair fatty acid oxidation in iPLA2β-null mice. Our findings therefore reveal a novel function of iPLA2β, related not to its phospholipase activity but to its thioesterase activity, which contributes to optimal fatty acid oxidation in skeletal muscle. PMID:18937505

  7. Side Effects of Chemotherapy

    MedlinePlus

    ... effects are being addressed. Many of these side effects, especially fever and inability to keep food/drink down, need to be addressed right away – don’t wait until your next appointment to tell your provider Terms ... from this article: Side Effect A problem that occurs when treatment affects tissues ...

  8. Medications and Side Effects

    MedlinePlus

    ... medication without first talking with your doctor. SIDE EFFECT Lack of energy/ fatigue/ sleepiness Dry mouth Weight gain ... 16 © 2004 Depression and Bipolar Support Alliance SIDE ... of day take medication is taken. I Go to sleep and wake up at the same time every ...

  9. [Side effects of antibiotics].

    PubMed

    Hoigné, R

    1975-03-01

    The clinically severe and newer forms of antibiotic side effects are reviewed. The study covers the following antibiotics: penicillins, cephalosporins, aminoglycosides and polymyxins, tetracyclines, chloramphenicol and thiamphenicol, macrolides and lincomycin, rifamycins and sulfonamides. Special reference is made to (1) hematologic side effects, and (2) general evaluation of drug reactions. The relationship between reaction time and clinical symptoms is of particular practical significance.

  10. Side Effects of Contingent Shock Treatment

    ERIC Educational Resources Information Center

    van Oorsouw, W. M. W. J.; Israel, M. L.; von Heyn, R. E.; Duker, P. C.

    2008-01-01

    In this study, the side effects of contingent shock (CS) treatment were addressed with a group of nine individuals, who showed severe forms of self-injurious behavior (SIB) and aggressive behavior. Side effects were assigned to one of the following four behavior categories; (a) positive verbal and nonverbal utterances, (b) negative verbal and…

  11. Interaction of bovine serum albumin with N-acyl amino acid based anionic surfactants: Effect of head-group hydrophobicity.

    PubMed

    Ghosh, Subhajit; Dey, Joykrishna

    2015-11-15

    The function of a protein depends upon its structure and surfactant molecules are known to alter protein structure. For this reason protein-surfactant interaction is important in biological, pharmaceutical, and cosmetic industries. In the present work, interactions of a series of anionic surfactants having the same hydrocarbon chain length, but different amino acid head group, such as l-alanine, l-valine, l-leucine, and l-phenylalanine with the transport protein, bovine serum albumin (BSA), were studied at low surfactant concentrations using fluorescence and circular dichroism (CD) spectroscopy, and isothermal titration calorimetry (ITC). The results of fluorescence measurements suggest that the surfactant molecules bind simultaneously to the drug binding site I and II of the protein subdomain IIA and IIIA, respectively. The fluorescence as well as CD spectra suggest that the conformation of BSA goes to a more structured state upon surfactant binding at low concentrations. The binding constants of the surfactants were determined by the use of fluorescence as well as ITC measurements and were compared with that of the corresponding glycine-derived surfactant. The binding constant values clearly indicate a significant head-group effect on the BSA-surfactant interaction and the interaction is mainly hydrophobic in nature.

  12. D-π-A dye system containing cyano-benzoic acid as anchoring group for dye-sensitized solar cells.

    PubMed

    Katono, Masataka; Bessho, Takeru; Meng, Sheng; Humphry-Baker, Robin; Rothenberger, Guido; Zakeeruddin, Shaik M; Kaxiras, Efthimios; Grätzel, Michael

    2011-12-06

    A D-π-A dye (KM-1) incorporating cyano-benzoic acid as a new acceptor/anchoring group has been synthesized for dye-sensitized solar cells (DSCs) with a high molar extinction coefficient of 66,700 M(-1) cm(-1) at 437 nm. Theoretical calculations show that the hydrogen bond between -CN and surface hydroxyl leads to the most stable configuration on the surface of TiO(2). In addition, the adsorption of the dye on TiO(2) follows a Brunauer-Emmett-Teller (BET) isotherm. Multilayer adsorption of KM-1 on TiO(2) seems to take place particularly at higher dye concentrations. DSC device using KM-1 reached a maximum incident photon-to-current conversion efficiency (IPCE) of 84%, with a solar to electric power conversion efficiency (PCE) of 3.3% at AM1.5 G illumination (100 mW cm(-2)). This new type of anchoring group paves a way to design new dyes that combine good visible light harvesting with strong binding to the metal oxide surface.

  13. Gas-phase acidities of aspartic acid, glutamic acid, and their amino acid amides

    NASA Astrophysics Data System (ADS)

    Li, Zhong; Matus, Myrna H.; Velazquez, Hector Adam; Dixon, David A.; Cassady, Carolyn J.

    2007-09-01

    Gas-phase acidities (GA or [Delta]Gacid) for the two most acidic common amino acids, aspartic acid and glutamic acid, have been determined for the first time. Because of the amide linkage's importance in peptides and as an aid in studying side chain versus main chain deprotonation, aspartic acid amide and glutamic acid amide were also studied. Experimental GA values were measured by proton transfer reactions in an electrospray ionization/Fourier transform ion cyclotron resonance mass spectrometer. Calculated GAs were obtained by density functional and molecular orbital theory approaches. The best agreement with experiment was found at the G3MP2 level; the MP2/CBS and B3LYP/aug-cc-pVDZ results are 3-4 kcal/mol more acidic than the G3MP2 results. Experiment shows that aspartic acid is more acidic than glutamic acid by ca. 3 kcal/mol whereas the G3MP2 results show a smaller acidity difference of 0.2 kcal/mol. Similarly, aspartic acid amide is experimentally observed to be ca. 2 kcal/mol more acidic than glutamic acid amide whereas the G3MP2 results show a correspondingly smaller energy difference of 0.7 kcal/mol. The computational results clearly show that the anions are all ring-like structures with strong hydrogen bonds between the OH or NH2 groups and the CO2- group from which the proton is removed. The two amino acids are main-chain deprotonated. In addition, use of the COSMO model for the prediction of the free energy differences in aqueous solution gave values in excellent agreement with the most recent experimental values for pKa. Glutamic acid is predicted to be more acidic than aspartic acid in aqueous solution due to differential solvation effects.

  14. Theoretical study of chlordecone and surface groups interaction in an activated carbon model under acidic and neutral conditions.

    PubMed

    Gamboa-Carballo, Juan José; Melchor-Rodríguez, Kenia; Hernández-Valdés, Daniel; Enriquez-Victorero, Carlos; Montero-Alejo, Ana Lilian; Gaspard, Sarra; Jáuregui-Haza, Ulises Javier

    2016-04-01

    Activated carbons (ACs) are widely used in the purification of drinking water without almost any knowledge about the adsorption mechanisms of the persistent organic pollutants. Chlordecone (CLD, Kepone) is an organochlorinated synthetic compound that has been used mainly as agricultural insecticide. CLD has been identified and listed as a persistent organic pollutant by the Stockholm Convention. The selection of the best suited AC for this type of contaminants is mainly an empirical and costly process. A theoretical study of the influence of AC surface groups (SGs) on CLD adsorption is done in order to help understanding the process. This may provide a first selection criteria for the preparation of AC with suitable surface properties. A model of AC consisting of a seven membered ring graphene sheet (coronene) with a functional group on the edge was used to evaluate the influence of the SGs over the adsorption. Multiple Minima Hypersurface methodology (MMH) coupled with PM7 semiempirical Hamiltonian was employed in order to study the interactions of the chlordecone with SGs (hydroxyl and carboxyl) at acidic and neutral pH and different hydration conditions. Selected structures were re-optimized using CAM-B3LYP to achieve a well-defined electron density to characterize the interactions by the Quantum Theory of Atoms in Molecules approach. The deprotonated form of surface carboxyl and hydroxyl groups of AC models show the strongest interactions, suggesting a chemical adsorption. An increase in carboxylic SGs content is proposed to enhance CLD adsorption onto AC at neutral pH conditions.

  15. A self-crosslinking thermosetting monomer with both epoxy and anhydride groups derived from Tung oil fatty acids: Synthesis and properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A self-crosslinking compound with epoxy groups and anhydride groups (GEMA) has been successfully synthesized from Tung oil fatty acid by reacting with maleic anhydride via the Diels-Alder reaction. GEMA has very good storage stability and can be cured with trace amounts of tertiary amine. This advan...

  16. A self-crosslinking thermosetting monomer with both epoxy and anhydride groups derived from tung oil fatty acids: Synthesis and properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A self-crosslinking compound with epoxy groups and anhydride groups (GEMA) has been successfully synthesized from tung oil fatty acid by reacting with maleic anhydride via the Diels-Alder reaction. GEMA has very good storage stability and could be cured with trace amounts of tertiary amine. This ad...

  17. The role of hydroxyl group acidity on the activity of silica-supported secondary amines for the self-condensation of n-butanal.

    PubMed

    Shylesh, Sankaranarayanapillai; Hanna, David; Gomes, Joseph; Canlas, Christian G; Head-Gordon, Martin; Bell, Alexis T

    2015-02-01

    The catalytic activity of secondary amines supported on mesoporous silica for the self-condensation of n-butanal to 2-ethylhexenal can be altered significantly by controlling the Brønsted acidity of M--OH species present on the surface of the support. In this study, M--OH (M=Sn, Zr, Ti, and Al) groups were doped onto the surface of SBA-15, a mesoporous silica, prior to grafting secondary propyl amine groups on to the support surface. The catalytic activity was found to depend critically on the synthesis procedure, the nature and amount of metal species introduced and the spatial separation between the acidic sites and amine groups. DFT analysis of the reaction pathway indicates that, for weak Brønsted acid groups, such as Si--OH, the rate-limiting step is C--C bond formation, whereas for stronger Brønsted acid groups, such as Ti and Al, hydrolysis of iminium species produced upon C--C bond formation is the rate-limiting step. Theoretical analysis shows further that the apparent activation energy decreases with increasing Brønsted acidity of the M--OH groups, consistent with experimental observation.

  18. Metabolic Glycoengineering with N-Acyl Side Chain Modified Mannosamines.

    PubMed

    Wratil, Paul R; Horstkorte, Rüdiger; Reutter, Werner

    2016-08-08

    In metabolic glycoengineering (MGE), cells or animals are treated with unnatural derivatives of monosaccharides. After entering the cytosol, these sugar analogues are metabolized and subsequently expressed on newly synthesized glycoconjugates. The feasibility of MGE was first discovered for sialylated glycans, by using N-acyl-modified mannosamines as precursor molecules for unnatural sialic acids. Prerequisite is the promiscuity of the enzymes of the Roseman-Warren biosynthetic pathway. These enzymes were shown to tolerate specific modifications of the N-acyl side chain of mannosamine analogues, for example, elongation by one or more methylene groups (aliphatic modifications) or by insertion of reactive groups (bioorthogonal modifications). Unnatural sialic acids are incorporated into glycoconjugates of cells and organs. MGE has intriguing biological consequences for treated cells (aliphatic MGE) and offers the opportunity to visualize the topography and dynamics of sialylated glycans in vitro, ex vivo, and in vivo (bioorthogonal MGE).

  19. Root Cellar: Plan, Southeast/Side Elevation, Northwest/Side Elevation, Northeast/Side Elevation, Southwest/Side ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Root Cellar: Plan, Southeast/Side Elevation, Northwest/Side Elevation, Northeast/Side Elevation, Southwest/Side Elevation - Driapsa Centennial Farm, Potts Hill European Community, 4511 Potts Hill Road, Bainbridge, Ross County, OH

  20. Molecular design of boronic acid-functionalized squarylium cyanine dyes for multiple discriminant analysis of sialic acid in biological samples: selectivity toward monosaccharides controlled by different alkyl side chain lengths.

    PubMed

    Ouchi, Kazuki; Colyer, Christa L; Sebaiy, Mahmoud; Zhou, Jin; Maeda, Takeshi; Nakazumi, Hiroyuki; Shibukawa, Masami; Saito, Shingo

    2015-02-03

    We designed a new series of boronic acid-functionalized squarylium cyanine dyes (SQ-BA) with different lengths of alkyl chain residues, suitable for multiple discriminant analysis (MDA) of sialic acid (Neu5Ac) in biological samples. The SQ-BA dyes form aggregates based on hydrophobic interactions, which result in quenched fluorescence in aqueous solutions. When the boronic acid binds with saccharides, the fluorescence intensity increases as a result of dissociation to the emissive monomeric complex. We inferred that different dye aggregate structures (H-aggregates and J-aggregates) were induced depending on the alkyl chain length, so that monosaccharides would be recognized in different ways (especially, multipoint interaction with J-aggregates). A distinctive emission enhancement of SQ-BA dyes with shorter-alkyl-chains in the presence of Neu5Ac was observed (2.4-fold fluorescence enhancement; with formation constant 10(1.7) M(-1)), with no such enhancement for SQ-BA dyes with longer-alkyl-chain. In addition, various enhancement factors for other monosaccharides were observed depending on the alkyl chain length. Detailed thermodynamic and NMR studies of the SQ-BA complexes revealed the unique recognition mechanism: the dye aggregate with a shorter-alkyl-chain causes the slipped parallel structure and forms a stable 2:1 complex with Neu5Ac, as distinct from longer-alkyl-chain dyes, which form a 1:1 monomeric complex. MDA using the four SQ-BA dyes was performed for human urine samples, resulting in the successful discrimination between normal and abnormal Neu5Ac levels characteristic of disease. Thus, we successfully controlled various responses to similar monosaccharides with a novel approach that chemically modified not the boronic acid moiety itself but the length of the alkyl chain residue attached to the dye in order to generate specificity.

  1. Electrophilic amination of amino acids with N-Boc-oxaziridines: efficient preparation of N-orthogonally diprotected hydrazino acids and piperazic acid derivatives.

    PubMed

    Hannachi, Jean-Christophe; Vidal, Joëlle; Mulatier, Jean-Christophe; Collet, André

    2004-04-02

    A general two-step preparation of enantiopure N(alpha),N(beta)-orthogonally diprotected alpha-hydrazino acids 1 is developed on a multigram scale. The key reaction is the efficient electrophilic amination of N-benzyl amino acids 6 with N-Boc-oxaziridine 7 and accommodates various functional groups encountered in side chains of amino acids. The cyclic 2,3,4,5-tetrahydro-3-pyridazine carboxylic acid (piperazic acid) derivatives 2 and 3 or the cyclic 3,4-dihydro-3-pyrazolecarboxylate 4 are conveniently prepared from glutamic acid or aspartic acid via orthogonally diprotected alpha-hydrazino acids 1m and 1n.

  2. Two Droplets Burning Side by Side

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Fiber-Supported Droplet Combustion (FSDC) experiment team got more than twice as many burns have been completed as were originally scheduled for STS-95. This image was taken July 12, 1997, MET:10/08:13 (approximate). As shown here, scientists were able to burn two droplets side by side, more closely mimicking behavior of burning fuel in an engine. This shows ignition of a single drop that subsequently burned while a fan blew through the chamber, giving the scientists data on burning with convection, but no buoyancy -- an important distinction when you're trying to solve a problem by breaking it into parts. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (1.1 MB, 11-second MPEG, screen 320 x 240 pixels; downlinked video, higher quality not available) A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300176.html.

  3. “Head-to-Side-Chain” Cyclodepsipeptides of Marine Origin

    PubMed Central

    Pelay-Gimeno, Marta; Tulla-Puche, Judit; Albericio, Fernando

    2013-01-01

    Since the late 1980s, a large number of depsipeptides that contain a new topography, referred to as “head-to-side-chain” cyclodepsipeptides, have been isolated and characterized. These peptides present a unique structural arrangement that comprises a macrocyclic region closed through an ester bond between the C-terminus and a β-hydroxyl group, and terminated with a polyketide moiety or a more simple branched aliphatic acid. This structural pattern, the presence of unique and complex residues, and relevant bioactivity are the main features shared by all the members of this new class of depsipeptides, which are reviewed herein. PMID:23697952

  4. Group A streptococcus cell-associated pathogenic proteins as revealed by growth in hyaluronic acid-enriched media.

    PubMed

    Zhang, Meng; McDonald, Fiona M; Sturrock, Shane S; Charnock, Simon J; Humphery-Smith, Ian; Black, Gary W

    2007-05-01

    Group A streptococcus (GAS), also know as Streptococcus pyogenes, is a human pathogen and can cause several fatal invasive diseases such as necrotising fasciitis, the so-called flesh-eating disease, and toxic shock syndrome. The destruction of connective tissue and the hyaluronic acid (HA) therein, is a key element of GAS pathogenesis. We therefore propagated GAS in HA-enriched growth media in an attempt to create a simple biological system that could reflect some elements of GAS pathogenesis. Our results show that several recognised virulence factors were up-regulated in HA-enriched media, including the M1 protein, a collagen-like surface protein and the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase, which has been shown to play important roles in streptococcal pathogenesis. Interestingly, two hypothetical proteins of unknown function were also up-regulated and detailed bioinformatics analysis showed that at least one of these hypothetical proteins is likely to be involved in pathogenesis. It was therefore concluded that this simple biological system provided a valuable tool for the identification of potential GAS virulence factors.

  5. Dicarboxylic acid anhydride condensation with compounds containing active methylene groups. 4: Some 4-nitrophthalic anhydride condensation reactions

    NASA Technical Reports Server (NTRS)

    Oskaja, V.; Rotberg, J.

    1985-01-01

    By 4-nitrophthalic anhydride condensation with acetoacetate in acetic anhydride and triethylamine solution with subsequent breakdown of the intermediate condensation product, 5-nitroindanedione-1,3 was obtained. A 4-nitrophthalic anhydride with acetic anhydride, according to reaction conditions, may yield two products: in the presence of potassium acetate and at high temperatures 4-(or 5-)-nitro-2-acetylbenzoic acid is formed: in the presence of triethylamine and at room temperature 5-( or 6-)-nitrophthalic acetic acid is isolated. A 4-nitrophthalic anhydride and malonic acid in pyridine solution according to temperature yield either 5-( or 6-)-nitrophthalic acetic acid or 4-(or 5-)-nitro-2-acetylbenzoic acid.

  6. Fatty acid dietary intake and the risk of ischaemic stroke: a multicentre case-control study. UFA Study Group.

    PubMed

    Ricci, S; Celani, M G; Righetti, E; Caruso, A; De Medio, G; Trovarelli, G; Romoli, S; Stragliotto, E; Spizzichino, L

    1997-06-01

    A low dietary intake of unsaturated fatty acids has been found in male patients with stroke as compared with controls in Italy, and a high consumption of meat has been associated with an increased risk of stroke in Australia. We present a case-control study, comparing the unsaturated and saturated fatty acids content of red cell membranes (which reflects the dietary intake of saturated and unsaturated fats) in 89 patients with ischaemic stroke and 89 controls matched for age and sex. In univariate analysis, besides hypertension, atrial fibrillation, ischaemic changes in ECG and hypercholesterolaemia, stroke patients showed a lower level of oleic acid (P = 0.000), but a higher level of eicosatrienoic acid (P = 0.009). Conditional logistic regression (dependent variable; being a case) showed that the best model included atrial fibrillation, hypertension, oleic acid and eicosatrienoic acids. These results confirm a possible protective role of unsaturated fatty acids against vascular diseases; however, we did not find any difference in the content of omega3 acids, which have been considered in the past to protect against coronary heart disease. We conclude that the preceding diet of patients with ischaemic stroke may be poor in unsaturated fatty acids (namely, oleic acid), and this defect is independent of other vascular risk factors. Only further studies will show whether changes in diet and/or supplement of unsaturated fatty acids might reduce the incidence of ischaemic stroke.

  7. Preparation of water-soluble hyperbranched polyester nanoparticles with sulfonic acid functional groups and their micelles behavior, anticoagulant effect and cytotoxicity.

    PubMed

    Han, Qiaorong; Chen, Xiaohan; Niu, Yanlian; Zhao, Bo; Wang, Bingxiang; Mao, Chun; Chen, Libin; Shen, Jian

    2013-07-02

    Biocompatibility of nanoparticles has been attracting great interest in the development of nanoscience and nanotechnology. Herein, the aliphatic water-soluble hyperbranched polyester nanoparticles with sulfonic acid functional groups (HBPE-SO3 NPs) were synthesized and characterized. They are amphiphilic polymeric nanoparticles with hydrophobic hyperbranched polyester (HBPE) core and hydrophilic sulfonic acid terminal groups. Based on our observations, we believe there are two forms of HBPE-SO3 NPs in water under different conditions: unimolecular micelles and large multimolecular micelles. The biocompatibility and anticoagulant effect of the HBPE-SO3 NPs were investigated using coagulation tests, hemolysis assay, morphological changes of red blood cells (RBCs), complement and platelet activation detection, and cytotoxicity (MTT). The results confirmed that the sulfonic acid terminal groups can substantially enhance the anticoagulant property of HBPE, and the HBPE-SO3 NPs have the potential to be used in nanomedicine due to their good bioproperties.

  8. Hydrogen atoms in acetylsalicylic acid (Aspirin): the librating methyl group and probing the potential well in the hydrogen-bonded dimer

    NASA Astrophysics Data System (ADS)

    Wilson, Chick C.

    2001-02-01

    The structure of acetylsalicylic acid (2-(acetoyloxy)benzoic acid; Aspirin) has been studied by variable temperature single crystal neutron diffraction. The usual large torsional librational motion of the terminal methyl group is observed and its temperature dependence analysed using a simple model for the potential, yielding the force constant and barrier height for this motion. In addition, asymmetry of the scattering density of the proton involved in the hydrogen bond forming the carboxylic acid dimer motif is observed at temperatures above 200 K. This asymmetry is discussed in terms of its possible implications for the shape of the hydrogen bonding potential well.

  9. [Psychoanalysis and Side Effect].

    PubMed

    Shirahase, Joichiro

    2015-01-01

    A study of psychoanalysis from the perspective of side effects reveals that its history was a succession of measures to deal with its own side effects. This, however, does not merely suggest that, as a treatment method, psychoanalysis is incomplete and weak: rather, its history is a record of the growth and development of psychoanalysis that discovered therapeutic significance from phenomena that were initially regarded as side effects, made use of these discoveries, and elaborated them as a treatment method. The approach of research seen during the course of these developments is linked to the basic therapeutic approach of psychoanalysis. A therapist therefore does not draw conclusions about a patient's words and behaviors from a single aspect, but continues to make efforts to actively discover a variety of meanings and values from them, and to make the patient's life richer and more productive. This therapeutic approach is undoubtedly one of the unique aspects of psychoanalysis. I discuss the issue of psychoanalysis and side effects with the aim of clarifying this unique characteristic of psychoanalysis. The phenomenon called resistance inevitably emerges during the process of psychoanalytic treatment. Resistance can not only obstruct the progress of therapy; it also carries the risk of causing a variety of disadvantages to the patient. It can therefore be seen as an adverse effect. However, if we re-examine this phenomenon from the perspective of transference, we find that resistance is in fact a crucial tool in psychoanalysis, and included in its main effect, rather than a side effect. From the perspective of minimizing the character of resistance as a side effect and maximizing its character as a main effect, I have reviewed logical organization, dynamic evaluation, the structuring of treatment, the therapist's attitudes, and the training of therapists. I conclude by stating that psychoanalysis has aspects that do not match the perspective known as a side

  10. The Penicillium chrysogenum aclA gene encodes a broad-substrate-specificity acyl-coenzyme A ligase involved in activation of adipic acid, a side-chain precursor for cephem antibiotics.

    PubMed

    Koetsier, Martijn J; Gombert, Andreas K; Fekken, Susan; Bovenberg, Roel A L; van den Berg, Marco A; Kiel, Jan A K W; Jekel, Peter A; Janssen, Dick B; Pronk, Jack T; van der Klei, Ida J; Daran, Jean-Marc

    2010-01-01

    Activation of the cephalosporin side-chain precursor to the corresponding CoA-thioester is an essential step for its incorporation into the beta-lactam backbone. To identify an acyl-CoA ligase involved in activation of adipate, we searched in the genome database of Penicillium chrysogenum for putative structural genes encoding acyl-CoA ligases. Chemostat-based transcriptome analysis was used to identify the one presenting the highest expression level when cells were grown in the presence of adipate. Deletion of the gene renamed aclA, led to a 32% decreased specific rate of adipate consumption and a threefold reduction of adipoyl-6-aminopenicillanic acid levels, but did not affect penicillin V production. After overexpression in Escherichia coli, the purified protein was shown to have a broad substrate range including adipate. Finally, protein-fusion with cyan-fluorescent protein showed co-localization with microbody-borne acyl-transferase. Identification and functional characterization of aclA may aid in developing future metabolic engineering strategies for improving the production of different cephalosporins.

  11. Comparative Study on Single-Molecule Junctions of Alkane- and Benzene-Based Molecules with Carboxylic Acid/Aldehyde as the Anchoring Groups

    NASA Astrophysics Data System (ADS)

    Chen, Fang; Peng, Lin-Lu; Hong, Ze-Wen; Mao, Jin-Chuan; Zheng, Ju-Fang; Shao, Yong; Niu, Zhen-Jiang; Zhou, Xiao-Shun

    2016-08-01

    We have measured the alkane and benzene-based molecules with aldehyde and carboxylic acid as anchoring groups by using the electrochemical jump-to-contact scanning tunneling microscopy break junction (ECSTM-BJ) approach. The results show that molecule with benzene backbone has better peak shape and intensity than those with alkane backbone. Typically, high junction formation probability for same anchoring group (aldehyde and carboxylic acid) with benzene backbone is found, which contributes to the stronger attractive interaction between Cu and molecules with benzene backbone. The present work shows the import role of backbone in junction, which can guide the design molecule to form effective junction for studying molecular electronics.

  12. Using a Macroporous Silver Shell to Coat Sulfonic Acid Group-Functionalized Silica Spheres and Their Applications in Catalysis and Surface-Enhanced Raman Scattering.

    PubMed

    Ren, Guohong; Wang, Wenqin; Shang, Mengying; Zou, Hanzhi; Cheng, Shengwei

    2015-09-29

    In this paper, novel organic sulfonic acid group-functionalized silica spheres (SiO2-SO3H) were chosen as a template for fabricating core-shell SiO2-SO3H@Ag composite spheres by the seed-mediated growth method. The SiO2-SO3H spheres could be obtained easily by oxidation of the thiol group-terminated silica spheres (SiO2-SH) with H2O2. Due to the presence of sulfonic acid groups, the [Ag(NH3)2](+) ions were captured on the surface of the silica spheres, followed by in-site reduction to silver nanoseeds for further growth of the silver shell. By this strategy, the complete silver shell could be obtained, and the surface morphologies and structures of the silver shell could be controlled by adjusting the number of sulfonic acid groups on the silica spheres. A large number of sulfonic acid groups on the SiO2-SO3H spheres favored the formation of the macroporous silver shell, which was unique and exhibited good catalytic performance and a high surface-enhanced Raman scattering (SERS) enhancement ability.

  13. Combination of Electromembrane Extraction and Liquid-Phase Microextraction in a Single Step: Simultaneous Group Separation of Acidic and Basic Drugs.

    PubMed

    Huang, Chuixiu; Seip, Knut Fredrik; Gjelstad, Astrid; Shen, Xiantao; Pedersen-Bjergaard, Stig

    2015-07-07

    Electromembrane extraction (EME) and liquid-phase microextraction (LPME) were combined in a single step for the first time to realize simultaneous and clear group separation of basic and acidic drugs. Using 2-nitrophenyl octyl ether as the supported liquid membrane (SLM) for EME and dihexyl ether as the SLM for LPME, basic and acidic drugs were extracted and separated simultaneously from a low pH sample by EME and LPME, respectively. After 15 min of extraction, basic drugs (citalopram and sertraline) were exhaustively extracted, whereas the recoveries for acidic drugs (ketoprofen and ibuprofen) were in the range of 76%-86%. Longer extraction time provided higher recoveries for the acidic drugs, but this somewhat deteriorated the group separation. Matrices effects from the coexisting acidic drugs/basic drugs were tested, and we observed that simultaneous EME/LPME was not affected by coexisting drugs at high concentration. This approach was further investigated from human plasma. Extraction recoveries were strongly dependent on dilution of plasma with buffer and on extraction time. Finally, this simultaneous EME/LPME approach was evaluated in combination with liquid chromatography (LC)-MS. The linearity ranges for the basic and acidic drugs were 10-600 ng/mL and 1-60 μg/mL, respectively, with R(2) > 0.997 for all analytes. The repeatability at three different levels for all analytes was less than 15%. The limits of quantification (LOQ, S/N = 10) were found to be 4.0-6.3 ng/mL and 0.6-0.9 μg/mL for basic and acidic drugs, respectively. Simultaneous EME/LPME enabled efficient group separation of basic and acidic analytes under optimum experimental conditions for both EME and LPME.

  14. 3. VIEW NORTH, SOUTHWEST FRONT, SOUTHEAST SIDE Front and side ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW NORTH, SOUTHWEST FRONT, SOUTHEAST SIDE Front and side elevation. Note gasoline sign post added. Flush store window not altered, 1900 clapboard siding and panelling remaining. - 510 Central Avenue (Commercial Building), Ridgely, Caroline County, MD

  15. Oblique view of east side mechanical additions and south side ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oblique view of east side mechanical additions and south side of 1955 addition, facing northwest. - Albrook Air Force Station, Dispensary, East side of Canfield Avenue, Balboa, Former Panama Canal Zone, CZ

  16. Nucleic Acids Research Group (NRG): The Importance of DNA Extraction in Metagenomics: The Gatekeeper to Accurate Results!

    PubMed Central

    Carmical, R.; Nadella, V.; Herbert, Z.; Beckloff, N.; Chittur, S.; Rosato, C.; Perera, A.; Auer, H.; Robinson, M.; Tighe, S.; Holbrook, Jennifer

    2013-01-01

    It is well recognized that the field of metagenomics is becoming a critical tool for studying previously unobtainable population dynamics at both an identification of species level and a functional or transcriptional level. Because the power to resolve microbial information is so important for identifying the components in an mixed sample, metagenomics can be used to study nearly any possible environment or system including clinical, environmental, and industrial, to name a few. Clinically, it may be used to determine sub-populations colonizing regions of the body or determining a rare infection to assist in treatment strategies. Environmentally it may be used to identify microbial populations within a soil, water or air sample, or within a bioreactor to characterize a population- based functional process. The possibilities are endless. However, the accuracy of a metagenomics dataset relies on three important “gatekeepers” including 1) The ability to effectively extract all DNA or RNA from every cell within a sample, 2) The reliability of the methods used for deep or high-throughput sequencing, and 3) The software used to analyze the data. Since DNA extraction is the first step in the technical process of metagenomics, the Nucleic Acid Research Group (NARG) conducted a study to evaluate extraction methods using a synthetic microbial sample. The synthetic microbial sample was prepared from 10 known bacteria at specific concentrations and ranging in diversity. Samples were extracted in duplicate using various popular kit based methods as well as several homebrew protocols then analyzed by NextGen sequencing on an Illumina HiSeq. Results of the study include determining the percent recovery of those organisms by comparing to the known quantity in the original synthetic mix.

  17. Elucidating the role of the phenylacetic acid metabolic complex in the pathogenic activity of Rhizoctonia solani anastomosis group 3.

    PubMed

    Bartz, Faith E; Glassbrook, Norman J; Danehower, David A; Cubeta, Marc A

    2012-01-01

    The soil fungus Rhizoctonia solani produces phytotoxic phenylacetic acid (PAA) and hydroxy (OH-) and methoxy (MeO-) derivatives of PAA. However, limited information is available on the specific role that these compounds play in the development of Rhizoctonia disease symptoms and concentration(s) required to induce a host response. Reports that PAA inhibits the growth of R. solani conflict with the established ability of the fungus to produce and metabolize PAA. Experiments were conducted to clarify the role of the PAA metabolic complex in Rhizoctonia disease. In this study the concentration of PAA and derivatives required to induce tomato root necrosis and stem canker, in the absence of the fungus, and the concentration that inhibits mycelial growth of R. solani were determined. The effect of exogenous PAA and derivatives of PAA on tomato seedling growth also was investigated. Growth of tomato seedlings in medium containing 0.1-7.5 mM PAA and derivatives induced necrosis of up to 85% of root system. Canker development resulted from injection of tomato seedling stems with 7.5 mM PAA, 3-OH-PAA, or 3-MeO-PAA. PAA in the growth medium reduced R. solani biomass, with 50% reduction observed at 7.5 mM. PAA, and derivatives were quantified from the culture medium of 14 isolates of R. solani belonging to three distinct anastomosis groups by GC-MS. The quantities ranged from below the limit of detection to 678 nM, below the concentrations experimentally determined to be phytotoxic. Correlation analyses revealed that isolates of R. solani that produced high PAA and derivatives in vitro also caused high mortality on tomato seedlings. The results of this investigation add to the body of evidence that the PAA metabolic complex is involved in Rhizoctonia disease development but do not indicate that production of these compounds is the primary or the only determinant of pathogenicity.

  18. OH-radical induced degradation of hydroxybenzoic- and hydroxycinnamic acids and formation of aromatic products—A gamma radiolysis study

    NASA Astrophysics Data System (ADS)

    Krimmel, Birgit; Swoboda, Friederike; Solar, Sonja; Reznicek, Gottfried

    2010-12-01

    The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement -OCH 3 by -OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC-UV and LC-ESI-MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed.

  19. Clinical Usefulness of Oral Supplementation with Alpha-Lipoic Acid, Curcumin Phytosome, and B-Group Vitamins in Patients with Carpal Tunnel Syndrome Undergoing Surgical Treatment

    PubMed Central

    Pajardi, Giorgio; Bortot, Paola; Ponti, Veronica; Novelli, Chiara

    2014-01-01

    We investigated the clinical usefulness of oral supplementation with a combination product containing alpha-lipoic acid, curcumin phytosome, and B-group vitamins in 180 patients with carpal tunnel syndrome (CTS), scheduled to undergo surgical decompression of the median nerve. Patients in Group A (n = 60) served as controls and did not receive any treatment either before or after surgery. Patients in Group B (n = 60) received oral supplementation twice a day for 3 months both before and after surgery (totaling 6 months of supplementation). Patients in Group C (n = 60) received oral supplementation twice a day for 3 months before surgery only. Patients in Group B showed significantly lower nocturnal symptoms scores compared with Group A subjects at both 40 days and 3 months after surgery (both P values <0.05). Moreover, patients in Group B had a significantly lower number of positive Phalen's tests at 3 months compared with the other study groups (P < 0.05). We conclude that oral supplementation with alpha-lipoic acid, curcumin phytosome, and B-group vitamins twice a day both before and after surgery is safe and effective in CTS patients scheduled to undergo surgical decompression of the median nerve. PMID:24563654

  20. Is combined topical with intravenous tranexamic acid superior than topical, intravenous tranexamic acid alone and control groups for blood loss controlling after total knee arthroplasty

    PubMed Central

    Lin, Chunmei; Qi, Yingmei; Jie, Li; Li, Hong-biao; Zhao, Xi-cheng; Qin, Lei; Jiang, Xin-qiang; Zhang, Zhen-hua; Ma, Liping

    2016-01-01

    Abstract Background: The purpose of this systematic review and meta-analysis of randomized controlled trials (RCTs) was to evaluate the efficacy and safety of combined topical with intravenous tranexamic acid (TXA) versus topical, intravenous TXA alone or control for reducing blood loss after a total knee arthroplasty (TKA). Methods: In May 2016, a systematic computer-based search was conducted in the PubMed, Embase, Cochrane Library, Web of Science, and Chinese Wanfang database. This systematic review and meta-analysis were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement criteria. Only patients prepared for primary TKA that administration combined topical with intravenous TXA with topical TXA, intravenous (IV) TXA, or control group for reducing blood loss were included. Eligible criteria were published RCTs about combined topical with intravenous TXA with topical alone or intravenous alone. The primary endpoint was the total blood loss and need for transfusion. The complications of deep venous thrombosis (DVT) were also compiled to assess the safety of combined topical TXA with intravenous TXA. Relative risks (RRs) with 95% CIs were estimated for dichotomous outcomes, and mean differences (MDs) with 95% CIs for continuous outcomes. The Cochrane risk of bias tool was used to appraise a risk of bias. Stata 12.0 software was used for meta-analysis. Results: Fifteen studies involving 1495 patients met the inclusion criteria. The pooled meta-analysis indicated that combined topical TXA with intravenous TXA can reduce the total blood loss compared with placebo with a mean of 458.66 mL and the difference is statistically significant (MD = −458.66, 95% CI: −655.40 to 261.91, P < 0.001). Compared with intravenous TXA, combined administrated TXA can decrease the total blood loss, and the difference is statistically significant (MD = −554.03, 95% CI: −1066.21 to −41.85, P = 0

  1. Biologically produced acid precipitable polymeric lignin

    DOEpatents

    Crawford, Don L.; Pometto, III, Anthony L.

    1984-01-01

    A water soluble, acid precipitable polymeric degraded lignin (APPL), having a molecular weight of at least 12,000 daltons, and comprising, by percentage of total weight, at least three times the number of phenolic hydroxyl groups and carboxylic acid groups present in native lignin. The APPL may be modified by chemical oxidation and reduction to increase its phenolic hydroxyl content and reduce the number of its antioxidant inhibitory side chains, thereby improving antioxidant properties.

  2. Transesterification catalyzed by polystyrene-supported chymotrypsin in toluene: the effect of neutralization of basic or acidic groups attaching to polystyrene resins.

    PubMed

    Ohtani, N; Inoue, Y; Kobayashi, A; Sugawara, T

    1995-10-05

    Crosslinked polystyrene resins containing a low level of either basic or acidic groups were used for supports of alpha-chymotrypsin (CT), which catalyzed the transesterification of N-acetyl-L-phenylalanine ethyl ester (AcPheOEt) with propanol in toluene. With a minimal amount of water, CT was sorbed to the resins, basic or acidic groups of which were partly or fully neutralized by several soluble acids or bases. With an increasing degree of neutralization of basic resins by free acids, the rate of disappearance of AcPheOEt was decreased, whereas the by-product formation of AcPheOH, due to hydrolysis, was considerably suppressed, compared with the ester-exchange product, AcPheOPr. The pK(a) value of the neutralizing acid was also important for both CT activity and reaction selectivity. AcPheOPr was selectively produced at a certain range of pK(a) values. On the other hand, the neutralization of acidic resins with free amines enhanced the CT activity but a strong base promoted the formation of hydrolysis product.

  3. Complexation efficiency of differently fixed 8-hydroxyquinoline and salicylic acid ligand groups for labile aluminium species determination in soils--comparison of two methods.

    PubMed

    Matús, Peter; Kubová, Jana

    2006-07-28

    Two methods utilizing the complexation of labile Al species by 8-hydroxyquinoline (HQN) and salicylic acid (SA) ligand groups were developed for aluminium operationally defined fractionation in acid soils. First, the solid phase extraction (SPE) procedure by a short-term ion-exchange batch reaction with chelating resins Iontosorb Oxin and Iontosorb Salicyl containing both ligand groups was used previously. Second, the 8-hydroxyquinoline, salicylic acid and ammonium salicylate agents with different concentrations by a single extraction protocol were applied in this paper. The flame atomic absorption spectrometry (FAAS) and optical emission spectrometry with inductively coupled plasma were used for aluminium quantification. The comparison of results from both methods show the possibility to supersede the first laborious method for the second simpler one in Al environmental risk assessment. The use of 1% 8-hydroxyquinoline in 2% acetic acid and 0.2% salicylic acid by a single extraction protocol without a need of sample filtration can supersede the SPE procedure in the Al pollution soil monitoring. Finally, the new scheme usable in a laboratory and moreover, directly in a field was proposed for Al fractionation in solid and liquid environmental samples. The labile Al species in soils and sediments are separated after their single leaching by 8-hydroxyquinoline or salicylic acid without a need of sample filtration. The labile Al species in soil solutions and natural waters are separated after their ultrafiltration followed by the SPE procedure with Iontosorb Oxin or Iontosorb Salicyl.

  4. HIV Medicines and Side Effects

    MedlinePlus

    ... on a person’s individual needs. Can HIV medicines cause side effects? HIV medicines help people with HIV live longer, healthier lives. Sometimes HIV medicines can also cause side effects. Most side effects from HIV medicines are manageable, ...

  5. Huntsville South Side Square

    NASA Technical Reports Server (NTRS)

    1940-01-01

    This 1940s photo of the South side of Square in downtown Huntsville, Alabama, looking west, shows a historical bank in the background with cars parked just South of the Courthouse (not shown in photo). (Courtesy of Huntsville/Madison County Public Library)

  6. Classification of mouse VK groups based on the partial amino acid sequence to the first invariant tryptophan: impact of 14 new sequences from IgG myeloma proteins.

    PubMed

    Potter, M; Newell, J B; Rudikoff, S; Haber, E

    1982-12-01

    Fourteen new VK sequences derived from BALB/c IgG myeloma proteins were determined to the first invariant tryptophan (Trp 35). These partial sequences were compared with 65 other published VK sequences using a computer program. The 79 sequences were organized according to the length of the sequence from the amino terminus to the first invariant tryptophan (Trp 35), into seven groups (33, 34, 35, 36, 39, 40 and 41aa). A distance matrix of all 79 sequences was then computed, i.e. the number of amino acid substitutions necessary to convert one sequence to another was determined. From these data a dendrogram was constructed. Most of the VK sequences fell into clusters or closely related groups. The definition of a sequence group is arbitrary but facilitates the classification of VK proteins. We used 12 substitutions as the basis for defining a sequence group based on the known number of substitutions that are found in the VK21 proteins. By this criterion there were 18 groups in the Trp 35 dendrogram. Twelve of the 14 new sequences fell into one of these sequence groups; two formed new sequence groups. Collective amino acid sequencing is still encountering new VK structures indicating more sequences will be required to attain an accurate estimate of the total number of VK groups. Updated dendrograms can be quickly generated to include newly generated sequences.

  7. Functional groups and activities of bacteria in a highly acidic volcanic mountain stream and lake in Patagonia, Argentina.

    PubMed

    Wendt-Potthoff, Katrin; Koschorreck, M

    2002-01-01

    Acidic volcanic waters are naturally occurring extreme habitats that are subject of worldwide geochemical research but have been little investigated with respect to their biology. To fill this gap, the microbial ecology of a volcanic acidic river (pH approximately equal to 0-1.6), Rio Agrio, and the recipient lake Caviahue in Patagonia, Argentina, was studied. Water and sediment samples were investigated for Fe(II), Fe(III), methane, bacterial abundances, biomass, and activities (oxygen consumption, iron oxidation and reduction). The extremely acidic river showed a strong gradient of microbial life with increasing values downstream and few signs of life near the source. Only sulfide-oxidizing and fermentative bacteria could be cultured from the upper part of Rio Agrio. However, in the lower part of the system, microbial biomass and oxygen penetration and consumption in the sediment were comparable to non-extreme aquatic habitats. To characterize similarities and differences of chemically similar natural and man-made acidic waters, our findings were compared to those from acidic mining lakes in Germany. In the lower part of the river and the lake, numbers of iron and sulfur bacteria and total biomass in sediments were comparable to those known from acidic mining lakes. Bacterial abundance in water samples was also very similar for both types of acidic water (around 10(5) mL(-1)). In contrast, Fe(II) oxidation and Fe(III) reduction potentials appeared to be lower despite higher biogenic oxygen consumption and higher photosynthetic activity at the sediment-water interface. Surprisingly, methanogenesis was detected in the presence of high sulfate concentrations in the profundal sediment of Lake Caviahue. In addition to supplementing microbiological knowledge on acidic volcanic waters, our study provides a new view of these extreme sites in the general context of aquatic habitats.

  8. 4. VIEW EAST, SOUTHWEST FRONT, NORTHWEST SIDE Side elevation. Note ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW EAST, SOUTHWEST FRONT, NORTHWEST SIDE Side elevation. Note the ground floor windows which were added. Siding is vinyl, but the burned area exposes asbestos siding added when the rear and upper areas were converted to living spaces. - 510 Central Avenue (Commercial Building), Ridgely, Caroline County, MD

  9. 20 CFR 619.3 - Data exchange standardization for SIDES.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... standardization for SIDES. (a) XML is the data exchange standard for SIDES. (b) This standard applies to any Federally-funded SIDES consortium, and any future agents of the Department providing vendor services for the... consortium involves a group of two or more States jointly establishing a project team to oversee the...

  10. Effect of excess dietary iron as ferrous sulfate and excess dietary ascorbic acid on liver zinc, copper and sulfhydryl groups and the ovary

    SciTech Connect

    Edwards, C.H.; Adkins, J.S.; Harrison, B.

    1986-03-05

    Female guinea pigs of the NIH 13/N strain, weighing between 475 and 512 g, were fed diets supplemented with 50 to 2500 mg of iron per kg of diet as ferrous sulfate and 0.2 to 8.0 g of ascorbic acid per kg of diet. A significant effect was observed on tissue copper and zinc, ovary weight and liver protein sulfhydryl groups. The mean ovary weight for guinea pigs fed 2500 mg of iron was significantly less than that of animals fed 50 mg of iron, 0.045 +/- 0.012 g and 0.061 +/- 0.009 g, respectively. Liver zinc content of animals fed 2500 mg of iron and 200 mg of ascorbic acid per kg of diet was significantly less than that of animals fed 50 mg of iron and 200 mg of ascorbic acid, 16.3 +/- 3.3 ..mu..g and 19.6 +/- 1.6 ..mu..g, respectively. There was no difference in liver copper due to dietary iron, but when dietary ascorbic acid was increased to 8 g per kg of diet, there was a significant decrease (from 22.8 +/- 8.1 ..mu..g to 10.5 +/- 4.8 ..mu..g) in liver copper. Excess dietary ascorbic acid decreased ovarian zinc significantly when increased to 8 g per kg of diet, 2929 +/- 919 ..mu..g vs 1661 +/- 471 ..mu..g, respectively, when compared to the control group.

  11. Simulations: The dark side

    NASA Astrophysics Data System (ADS)

    Frenkel, D.

    2013-01-01

    This paper discusses the Monte Carlo and Molecular Dynamics methods. Both methods are, in principle, simple. However, simple does not mean risk-free. In the literature, many of the pitfalls in the field are mentioned, but usually as a footnote --and these footnotes are scattered over many papers. The present paper focuses on the "dark side" of simulation: it is one big footnote. I should stress that "dark", in this context, has no negative moral implication. It just means: under-exposed.

  12. Amino Acid Mean Excitation Energies and Directional Dependencies from Core and Bond Calculations

    SciTech Connect

    Sabin, John R.; Oddershede, Jens; Sauer, Stephan P. A.

    2008-12-08

    We determine the mean excitation energies of several amino acids using a Bragg Rule developed for molecular fragments or functional groups. As the composition of the amino acids is very similar, we find that the amino acids have similar mean excitation energies (approximately 70 eV). Differences arise from variation of the side chains (-R); addition of-CH2-groups decreases the mean excitation energy. We also speculate concerning the directional dependence of the amino acid mean excitation energies.

  13. Simple introduction of sulfonic acid group onto polyethylene by radiation-induced cografting of sodium styrenesulfonate with hydrophilic monomers. [electron beam

    SciTech Connect

    Tsuneda, Satoshi; Saito, Kyoichi; Furusaki, Shintaro . Dept. of Chemical Engineering); Sugo, Takanobu; Makuuchi, Keizo . Takasaki Radiation Chemistry Research Establishment)

    1993-07-01

    The sulfonic acid (SO[sub 3]H) group was readily introduced into a polyethylene (PE) membrane by radiation-induced cografting of sodium styrenesulfonate (SSS) with hydrophilic monomers such as acrylic acid (AAc) and hydroxyethyl methacrylate (HEMA). The density of SSS grafted onto the PE membrane was determined as a function of molar ratio of hydrophilic monomer to SSS in the monomer mixture. Immersion of the electron-beam-irradiated PE membrane into the mixture of SSS and HEMA for 5 h at 323 K provided to the SO[sub 3]H density of 2.5 mol/kg of the H-type product.

  14. Design, synthesis and evaluation of polar head group containing 2-keto-oxazole inhibitors of FAAH.

    PubMed

    Rusch, Marion; Zahov, Stefan; Vetter, Ingrid R; Lehr, Matthias; Hedberg, Christian

    2012-01-15

    2-α-Keto oxazoles containing polar head groups in their C5-side chains were designed as fatty acid amide hydrolase (FAAH) inhibitors. Variation in the spacer length resulted in submicromolar α-keto-oxazole FAAH inhibitor (IC(50)=436 nM) presenting electrostatic stabilizing interactions between its polar head group contained in the C5-side chain and the hydrophilic pocket of the enzyme.

  15. The Benzyl Ester Group of Amino Acid Monomers Enhances Substrate Affinity and Broadens the Substrate Specificity of the Enzyme Catalyst in Chemoenzymatic Copolymerization.

    PubMed

    Ageitos, Jose Manuel; Yazawa, Kenjiro; Tateishi, Ayaka; Tsuchiya, Kousuke; Numata, Keiji

    2016-01-11

    The chemoenzymatic polymerization of amino acid monomers by proteases involves a two-step reaction: the formation of a covalent acyl-intermediate complex between the protease and the carboxyl ester group of the monomer and the subsequent deacylation of the complex by aminolysis to form a peptide bond. Although the initiation with the ester group of the monomer is an important step, the influence of the ester group on the polymerization has not been studied in detail. Herein, we studied the effect of the ester groups (methyl, ethyl, benzyl, and tert-butyl esters) of alanine and glycine on the synthesis of peptides using papain as the catalyst. Alanine and glycine were selected as monomers because of their substantially different affinities toward papain. The efficiency of the polymerization of alanine and glycine benzyl esters was much greater than that of the other esters. The benzyl ester group therefore allowed papain to equally polymerize alanine and glycine, even though the affinity of alanine toward papain is substantially higher. The characterization of the copolymers of alanine and glycine in terms of the secondary structure and thermal properties revealed that the thermal stability of the peptides depends on the amino acid composition and resultant secondary structure. The current results indicate that the nature of the ester group drastically affects the polymerization efficiency and broadens the substrate specificity of the protease.

  16. The effects of group III mGluR ligands on pentylenetetrazol-induced kindling of seizures and hippocampal amino acids concentration.

    PubMed

    Maciejak, Piotr; Szyndler, Janusz; Turzyńska, Danuta; Sobolewska, Alicja; Taracha, Ewa; Skórzewska, Anna; Lehner, Małgorzata; Bidziński, Andrzej; Hamed, Adam; Wisłowska-Stanek, Aleksandra; Płaźnik, Adam

    2009-07-28

    Considering the contribution of hippocampal formation and glutamate-mediated signalling to epileptogenesis, we investigated the effects of group III metabotropic glutamate receptor (mGluR)-selective ligands on the kindling of seizures. We also examined the concentration of the amino acid glutamate, GABA, alanine and taurine in the hippocampus of rats using a microdialysis technique. Pentylenetetrazol (PTZ), a non-competitive antagonist of the GABA(A) receptor, was administered intraperitoneally at 35 mg/kg body weight to induce seizures. It was determined that the kindling of PTZ-induced seizures could be attenuated by post intracerebroventricular administration of 100 nmol of the group III mGluR antagonist CPPG [(RS)-a-cyclopropyl-4-phosphonophenylglycine]. There were significant differences in tested parameters during the final stages of the kindling procedure. The group III mGluR agonist L-AP4 [L-(+)-2-amino-4-phosphonobutyric acid at 100 nmol, i.c.v.] did not significantly affect the kindling of seizures in comparison to control rats, although there was acceleration of the process as compared to CPPG treated animals. We demonstrated that the baseline concentrations of glutamate, GABA, alanine, taurine, and the glutamine/GABA ratio were elevated in the hippocampus of fully kindled rats. Intracerebroventricular administration of a single dose of CPPG increased the concentrations of glutamate in the hippocampus of control, non-kindled rats. Intracerebroventricular administration of L-AP4 did not affect the hippocampal amino acid concentration in either animal group. Overall, these data suggest that there is a shift in the balance between neurotransmitters towards increased production of excitatory amino acids, and this may be mediated by group III mGluRs during seizure kindling.

  17. Flapping propulsion with side-by-side pitching foils

    NASA Astrophysics Data System (ADS)

    Huera-Huarte, Francisco

    2016-11-01

    Fish schools are one of the most common types of collective behaviour observed in nature. One of the reasons why fish swim in groups, is to reduce the cost of transport of the school. In this work we explore the propulsive performance of two foils flapping in a symmetric configuration, i.e. with an out-of-phase flapping motion. Direct thrust measurements and Particle Image Velocimetry (PIV) allowed a detailed examination of the forces and the wake generated by the system, for different kinematics (swept angles and frequencies) and shaft separations. For certain specific cases, volumetric PIV shows major differences on how the different structures in the wake of the system evolve, depending on the imposed kinematics and the side-by-side separation between the foils. Results obtained will be compared against data produced with isolated flapping foils with similar imposed kinematics, with the aim to better understand the interactions between both and the performance of the system as a whole. The author would like to acknowledge the financial support provided by the Spanish Ministerio de Economia y competitividad (MINECO) through Grant DPI2015-71645-P.

  18. Synthesis, structural characterization and antimicrobial activities of diorganotin(IV) complexes with azo-imino carboxylic acid ligand: Crystal structure and topological study of a doubly phenoxide-bridged dimeric dimethyltin(IV) complex appended with free carboxylic acid groups

    NASA Astrophysics Data System (ADS)

    Roy, Manojit; Roy, Subhadip; Devi, N. Manglembi; Singh, Ch. Brajakishor; Singh, Keisham Surjit

    2016-09-01

    Diorganotin(IV) complexes appended with free carboxylic acids were synthesized by reacting diorganotin(IV) dichlorides [R2SnCl2; R = Me (1), Bu (2) and Ph (3)] with an azo-imino carboxylic acid ligand i.e. 2-{4-hydroxy-3-[(2-hydroxyphenylimino)methyl]phenylazo}benzoic acid in presence of triethylamine. The complexes were characterized by elemental analysis, IR and multinuclear NMR (1H, 13C and 119Sn) spectroscopy. The structure of 1 in solid state has been determined by X-ray crystallography. Crystal structure of 1 reveals that the compound crystallizes in monoclinic space group P21/c and is a dimeric dimethyltin(IV) complex appended with free carboxylic acid groups. In the structure of 1, the Sn(IV) atoms are hexacoordinated and have a distorted octahedral coordination geometry in which two phenoxy oxygen atoms and the azomethine nitrogen atom of the ligand coordinate to each tin atom. One of the phenoxy oxygen atom bridges the two tin centers resulting in a planar Sn2O2 core. Topological analysis is used for the description of molecular packing in 1. Tin NMR spectroscopy study indicates that the complexes have five coordinate geometry around tin atom in solution state. Since the complexes have free carboxylic acids, these compounds could be further used as potential metallo-ligands for the synthesis of other complexes. The synthesized diorganotin(IV) complexes were also screened for their antimicrobial activities and compound 2 showed effective antimicrobial activities.

  19. Analysis of carbon functional groups in mobile humic acid and recalcitrant calcium humate extracted from eight US soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Solid state 13C nuclear magnetic resonance (NMR) spectroscopy is a common tool to study the structure of soil humic fractions; however, knowledge regarding carbon structural relationships in humic fractions is limited. In this study, mobile humic acid (MHA) and recalcitrant calcium humate (CaHA) fr...

  20. Modification of humic acid by ether functional group as biosorbent to Au(III) adsorption in the presence of Sn(II) and Ni(II)

    NASA Astrophysics Data System (ADS)

    Yanti, Ika; Winata, Wahyu Fajar; Sudiono, Sri; Triyono

    2017-03-01

    Modification of humic acid on the phenolic functional group with dimethylsulfate (DMS) for adsorption Au(III) in the presence of Sn(II) and Ni(II) have been conducted. Ash content was analyzed and characterized by Fourier-Transform Infrared (FTIR). Determination of Au(III) adsorption in the presence of Sn(II) and Ni(II) was conducted by Atomic Adsorption Spectroscopy (AAS). The isolated humic acid has 19.8% ash content and after purification has 0.6% ash content, etherified humic acid (EHAs) has 1.4% ash content. Adsorption percentage of Au(III) in the presence of Sn(II) and Ni(II) by EHAs decreased until 4.936% and 41.782% respectively. The addition of Sn(II) and Ni(II) as competitors of Au(III) in the Au(III) adsorption by using EHAs, were affect the percentage of Au(III) adsorption.

  1. Extending cycle life of lead-acid batteries: a new separation system allows the application of pressure on the plate group

    NASA Astrophysics Data System (ADS)

    Perrin, M.; Döring, H.; Ihmels, K.; Weiss, A.; Vogel, E.; Wagner, R.

    Since 1983, it has been claimed that pressure applied on a lead-acid battery increases its cycle life. But until now, the use of pressure in production batteries was limited by the mechanical properties of the conventional separation systems (absorptive glass mat (AGM), and gel) which cannot withstand mechanical pressure. In 1997, Daramic developed the new acid jellying separator (AJS) with the aim of combining the advantages of both conventional separation systems and to allow the application of lasting plate group pressure. The new separation system was evaluated and much information was gained on the effect of pressure in a lead-acid battery, e.g. on the evolution of the mechanical pressure during one cycle and during cycle life.

  2. Cyclopropane-ring formation in the acyl groups of chlorosome glycolipids is crucial for acid resistance of green bacterial antenna systems.

    PubMed

    Mizoguchi, Tadashi; Tsukatani, Yusuke; Harada, Jiro; Takasaki, Shin; Yoshitomi, Taichi; Tamiaki, Hitoshi

    2013-07-01

    Green photosynthetic bacteria have unique light-harvesting antenna systems called chlorosomes. Chlorobaculum tepidum, a model organism of the bacteria, biosynthesized monogalactosyl- and rhamnosylgalactosyldiacylglycerides possessing a methylene-bridged palmitoleyl group characterized by a cis-substituted cyclopropane ring as the dominant glycolipids of its chlorosome surface. The formation of the cyclopropane ring was chemically inhibited by supplementation of sinefungin, an analog of S-adenosyl-L-methionine, into the bacterial cultivation. The presence of the cyclopropane ring reinforced acid resistance of the light-harvesting chlorosomes and suppressed acidic demetalation (pheophytinization) of bacteriochlorophyll-c pigments constructing the core part of chlorosomes. The ring-formation would represent direct and post-synthetic modifications of chlorosome membrane properties and was tolerant of acidic environments.

  3. Characterization of Group V Dubnium Homologs on DGA Extraction Chromatography Resin from Nitric and Hydrofluoric Acid Matrices

    SciTech Connect

    Despotopulos, J D; Sudowe, R

    2012-02-21

    somewhere between Nb and Pa. Much more recent studies have examined the properties of Db from HNO{sub 3}/HF matrices, and suggest Db forms complexes similar to those of Pa. Very little experimental work into the behavior of element 114 has been performed. Thermochromatography experiments of three atoms of element 114 indicate that the element 114 is at least as volatile as Hg, At, and element 112. Lead was shown to deposit on gold at temperatures about 1000 C higher than the atoms of element 114. Results indicate a substantially increased stability of element 114. No liquid phase studies of element 114 or its homologs (Pb, Sn, Ge) or pseudo-homologs (Hg, Cd) have been performed. Theoretical predictions indicate that element 114 is should have a much more stable +2 oxidation state and neutral state than Pb, which would result in element 114 being less reactive and less metallic than Pb. The relativistic effects on the 7p{sub 1/2} electrons are predicted to cause a diagonal relationship to be introduced into the periodic table. Therefore, 114{sup 2+} is expected to behave as if it were somewhere between Hg{sup 2+}, Cd{sup 2+}, and Pb{sup 2+}. In this work two commercially available extraction chromatography resins are evaluated, one for the separation of Db homologs and pseudo?homologs from each other as well as from potential interfering elements such as Group IV Rf homologs and actinides, and the other for separation of element 114 homologs. One resin, Eichrom's DGA resin, contains a N,N,N',N'-tetra-n-octyldiglycolamide extractant, which separates analytes based on both size and charge characteristics of the solvated metal species, coated on an inert support. The DGA resin was examined for Db chemical systems, and shows a high degree of selectivity for tri-, tetra-, and hexavalent metal ions in multiple acid matrices with fast kinetics. The other resin, Eichrom's Pb resin, contains a di-t-butylcyclohexano 18-crown-6 extractant with isodecanol solvent, which separates

  4. Dynamics of the separation of amino acid and mineral salt in the stationary dialysis of solutions with an MK-40 profiled sulfo group cation exchange membrane

    NASA Astrophysics Data System (ADS)

    Vasil'eva, V. I.; Vorob'eva, E. A.

    2012-11-01

    The conjugated diffusion transport of amino acid and mineral salt through a profiled sulfo group cation exchange membrane that simulates the extraction of amino acid from wash waters of microbiological production containing mineral components not used in synthesis is studied. The competitive nature of the conjugation of flows resulting in a decrease in the rate of the mass transfer of components and their separation factor is established from a comparative analysis of experimental data on the diffusion transfer of phenylalanine and sodium chloride in the form of hydrogen from individual and mixed solutions through a profiled sulfo group cation exchange membrane. The range of concentrations and the ratio of components in solution corresponding to the effective separation of phenylalanine and sodium chloride are determined.

  5. The cooperative effect between active site ionized groups and water desolvation controls the alteration of acid/base catalysis in serine proteases.

    PubMed

    Shokhen, Michael; Khazanov, Netaly; Albeck, Amnon

    2007-08-13

    What is the driving force that alters the catalytic function of His57 in serine proteases between general base and general acid in each step along the enzymatic reaction? The stable tetrahedral complexes (TC) of chymotrypsin with trifluoromethyl ketone transition state analogue inhibitors are topologically similar to the catalytic transition state. Therefore, they can serve as a good model to study the enzyme catalytic reaction. We used DFT quantum mechanical calculations to analyze the effect of solvation and of polar factors in the active site of chymotrypsin on the pKa of the catalytic histidine in FE (the free enzyme), EI (the noncovalent enzyme inhibitor complex), and TC. We demonstrated that the acid/base alteration is controlled by the charged groups in the active site--the catalytic Asp102 carboxylate and the oxyanion. The effect of these groups on the catalytic His is modulated by water solvation of the active site.

  6. Comparison of the influence of polyaspartic acid and polylysine functional groups on the adsorption at the Cr2O3-Aqueous polymer solution interface

    NASA Astrophysics Data System (ADS)

    Ostolska, Iwona; Wiśniewska, Małgorzata

    2014-08-01

    Polyamino acids are a group of synthesized polymers obtained by polymerization of a given kind of amino acid monomer. Because of high biodegradability of this class of polymers, they can be used as flocculation or stabilization agents in the environmental aspects. Therefore determination of their influence on the stability of the aqueous suspension of metal oxides is important. An influence of different functional groups of polyamino acids, their molecular weight and concentration on the adsorption at the chromium (III) oxide (Cr2O3)-aqueous solution interface was determined. Experiments were carried out for four values of solution pH varying from 3 to 10 (3, 4, 7.6 and 10, respectively). Two polymers were used: anionic polyaspartic acid (ASP) of 6800 and 27,000 as well as polylysine (LYS) of 4900 and 33,000 molecular weights. Changes of surface charge density of colloidal Cr2O3 in the presence and in the absence of macromolecular substances were determined using potentiometric titration. In these studies the influence of the concentration and molecular weight of the ionic polymers on the pHpzc value was determined. Additionally, due to the lack of appropriate literature data, potentiometric titration of the selected polymers was performed to determine pKa values.

  7. Synthesis and hybridization property of a boat-shaped pyranosyl nucleic acid containing an exocyclic methylene group in the sugar moiety.

    PubMed

    Mori, Kazuto; Kodama, Tetsuya; Obika, Satoshi

    2015-01-01

    A boat-shaped pyranosyl nucleic acid (BsNA) having an exocyclic methylene group in the sugar moiety was synthesized to investigate the possibility that the axial H3' of original BsNA is the cause of its duplex destabilization. The synthesized BsNA analog was chemically stable against various nucleophiles. From the thermal stability of duplex oligonucleotides including the BsNA analog, it was found that the duplex-forming ability can be sensitive to the size of functional groups at the 3'-position.

  8. Phosphorylation of lipin 1 and charge on the phosphatidic acid head group control its phosphatidic acid phosphatase activity and membrane association.

    PubMed

    Eaton, James M; Mullins, Garrett R; Brindley, David N; Harris, Thurl E

    2013-04-05

    The lipin gene family encodes a class of Mg(2+)-dependent phosphatidic acid phosphatases involved in the de novo synthesis of phospholipids and triglycerides. Unlike other enzymes in the Kennedy pathway, lipins are not integral membrane proteins, and they need to translocate from the cytosol to intracellular membranes to participate in glycerolipid synthesis. The movement of lipin 1 within the cell is closely associated with its phosphorylation status. Although cellular analyses have demonstrated that highly phosphorylated lipin 1 is enriched in the cytosol and dephosphorylated lipin 1 is found on membranes, the effects of phosphorylation on lipin 1 activity and binding to membranes has not been recapitulated in vitro. Herein we describe a new biochemical assay for lipin 1 using mixtures of phosphatidic acid (PA) and phosphatidylethanolamine that reflects its physiological activity and membrane interaction. This depends on our observation that lipin 1 binding to PA in membranes is highly responsive to the electrostatic charge of PA. The studies presented here demonstrate that phosphorylation regulates the ability of the polybasic domain of lipin 1 to recognize di-anionic PA and identify mTOR as a crucial upstream signaling component regulating lipin 1 phosphorylation. These results demonstrate how phosphorylation of lipin 1 together with pH and membrane phospholipid composition play important roles in the membrane association of lipin 1 and thus the regulation of its enzymatic activity.

  9. Human Disease Isolates of Serotype M4 and M22 Group A Streptococcus Lack Genes Required for Hyaluronic Acid Capsule Biosynthesis

    PubMed Central

    Flores, Anthony R.; Jewell, Brittany E.; Fittipaldi, Nahuel; Beres, Stephen B.; Musser, James M.

    2012-01-01

    ABSTRACT Group A streptococcus (GAS) causes human pharyngitis and invasive infections and frequently colonizes individuals asymptomatically. Many lines of evidence generated over decades have shown that the hyaluronic acid capsule is a major virulence factor contributing to these infections. While conducting a whole-genome analysis of the in vivo molecular genetic changes that occur in GAS during longitudinal human pharyngeal interaction, we discovered that serotypes M4 and M22 GAS strains lack the hasABC genes necessary for hyaluronic acid capsule biosynthesis. Using targeted PCR, we found that all 491 temporally and geographically diverse disease isolates of these two serotypes studied lack the hasABC genes. Consistent with the lack of capsule synthesis genes, none of the strains produced detectable hyaluronic acid. Despite the lack of a hyaluronic acid capsule, all strains tested multiplied extensively ex vivo in human blood. Thus, counter to the prevailing concept in GAS pathogenesis research, strains of these two serotypes do not require hyaluronic acid to colonize the upper respiratory tract or cause abundant mucosal or invasive human infections. We speculate that serotype M4 and M22 GAS have alternative, compensatory mechanisms that promote virulence. PMID:23131832

  10. Nafion-assisted cross-linking of sulfonated poly(arylene ether ketone) bearing carboxylic acid groups and their composite membranes for fuel cells

    NASA Astrophysics Data System (ADS)

    Lin, Haidan; Zhao, Chengji; Na, Hui

    In this study, a new type of cross-linked composite membrane is prepared and considered for its potential applications in direct methanol fuel cell. Nafion and sulfonated poly(arylene ether ketone) bearing carboxylic acid groups (SPAEK-C) are blended and subsequently cross-linked by a Friedel-Craft reaction using the carboxylic acid groups in the SPAEK-C to achieve lower methanol permeability. The perfluoroalkyl sulfonic acid groups of Nafion act as a benign solid catalyst, which assist the cross-linking of SPAEK-C. The physical and chemical characterizations of the cross-linked composite membranes are performed by varying the contents of SPAEK-C. The c-Nafion-15% membrane exhibits appropriate water uptake (10.49-25.22%), low methanol permeability (2.57 × 10 -7 cm 2 s -1), and high proton conductivity (0.179 S cm -1 at 80 °C). DSC and FTIR analyze suggest the cross-linking reaction. These results show that the self-cross-linking of SPAEK-C in the Nafion membrane can effectively reduce methanol permeability while maintaining high proton conductivity.

  11. The wall teichoic acids of Lactobacillus plantarum N.I.R.D. C106. Location of the phosphodiester groups and separation of the chains

    PubMed Central

    Archibald, A. R.; Coapes, Hilary E.

    1971-01-01

    1. The identities of the component glycerol glucosides of the wall teichoic acids of Lactobacillus plantarum N.I.R.D. C106 have been confirmed by methylation analysis. These glucosides are α-d-glucopyranosyl-(1→1)-l-glycerol, α-d-glucopyranosyl-(1→2)-α-d-glucopyranosyl-(1→1)-l-glycerol and α-d-glucopyranosyl-(1→3)-α-d-glucopyranosyl-(1→1)-l-glycerol. 2. These units are connected by phosphodiester groups attached to the 3(l)-hydroxyl group of glycerol and the 6-hydroxyl group of the non-reducing terminal glucose residues in the adjacent unit. 3. Concanavalin A forms a precipitate with the teichoic acid and the material so precipitated contains only the α-d-glucopyranosyl-(1→2)-α-d-glucopyranosyl -(1→1)-l-glycerol component. This unit is therefore present in a homogeneous polymer so that the teichoic acid is a mixture of this and of other possibly homogeneous chains containing the other two components. PMID:4332541

  12. 4. VIEW TO NORTH; SIDE SIDE OF RAMP IN FRONT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW TO NORTH; SIDE SIDE OF RAMP IN FRONT OF U.S. POST OFFICE TERMINAL ANNEX BUILDING (Dobson) - Los Angeles Union Passenger Terminal, Mail, Baggage, & Express Building, 800 North Alameda Street, Los Angeles, Los Angeles County, CA

  13. South (front) side. Metal railing to either side supports a ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    South (front) side. Metal railing to either side supports a door when it is open. - Fitzsimons General Hospital, Root Cellar, West Pennington Avenue, North of Building No. 121, Aurora, Adams County, CO

  14. VIEW OF FRONT SIDE OF BUILDING 23 FROM EAST SIDE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF FRONT SIDE OF BUILDING 23 FROM EAST SIDE OF COURTYARD UNDER ARCADE, FACING WEST - Roosevelt Base, Auditorium-Gymnasium, West Virginia Street between Richardson & Reeves Avenues, Long Beach, Los Angeles County, CA

  15. Front (west side) and north side of building with incinerator ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Front (west side) and north side of building with incinerator smokestack (building 615) in right background - Fitzsimons General Hospital, Incinerator Building, 540 feet East-Northeast of intersection of East Bushnell Avenue & South Van Valzah Street, Aurora, Adams County, CO

  16. 14. CO'S STATEROOM, STERN SIDE (LEFT) AND STARBOARD SIDE. NOTE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. CO'S STATEROOM, STERN SIDE (LEFT) AND STARBOARD SIDE. NOTE WOODEN WINDOW FRAMES. - U.S. Coast Guard Cutter WHITE LUPINE, U.S. Coast Guard Station Rockland, east end of Tillson Avenue, Rockland, Knox County, ME

  17. 1. SOUTH VIEW OF NORTHWEST SIDE, WITH NORTHEAST SIDE OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. SOUTH VIEW OF NORTHWEST SIDE, WITH NORTHEAST SIDE OF MINE OFFICE ON RIGHT OF PHOTO - Juniata Mill Complex, Assay Office, 22.5 miles Southwest of Hawthorne, between Aurora Crater & Aurora Peak, Hawthorne, Mineral County, NV

  18. FACILITY 858, PORTION OF NORTHEAST SIDE (APRON AVENUE SIDE), SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACILITY 858, PORTION OF NORTHEAST SIDE (APRON AVENUE SIDE), SHOWING CHEVRON DESIGN OVER FORMER PASSAGEWAY, OBLIQUE VIEW FACING WEST. - Schofield Barracks Military Reservation, Quadrangle K Barracks Type, Between Wilson Street & Capron Avenue near Williston Avenue, Wahiawa, Honolulu County, HI

  19. FACILITY 859, DETAIL OF SOUTHWEST SIDE (WILSON STREET SIDE), SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACILITY 859, DETAIL OF SOUTHWEST SIDE (WILSON STREET SIDE), SHOWING CHEVRON DESIGN OVER FORMER PASSAGEWAY, VIEW FACING NORTHEAST. - Schofield Barracks Military Reservation, Quadrangle K Barracks Type, Between Wilson Street & Capron Avenue near Williston Avenue, Wahiawa, Honolulu County, HI

  20. Rhizobins, a Group of Peptides in the Free-Amino-Acid Pool of the Soybean-Rhizobium System †

    PubMed Central

    Garay, Andrew S.; Ahlgren, Joy A.; Gonzalez, Mark A.; Stasney, Mark A.; Madtes, Paul C.

    1986-01-01

    Free-living Rhizobium (according to Bergey's Manual of Systematic Bacteriology, [1984, The Williams & Wilkins Co., Baltimore], Bradyrhizobium) japonicum was found to release a peptide into the nutrient media. Soybean nodules contained this peptide and exuded it into the soil. The name “rhizobin A” is suggested for this peptide. Nodules also contained another peptide, rhizobin B, as well as an unidentified, ninhydrin-positive compound, rhizobin C. The three peptides were confined to the free-amino-acid pool of the soluble fraction and eluted consecutively from a cation-exchange column. Rhizobin A was isolated in a highly purified form; its molecular mass was approximately 1,600 daltons as determined by Sephadex gel filtration and mass spectrometry. The amino-acid composition could be determined only approximately, because a long time was necessary for acid hydrolysis, possibly due to unusual linkages. The rhizobin concentration in soybean nodules continually increased during 50 days of growth, from 2 to approximately 400 μg/g (fresh weight). When combined nitrogen was added to nodulated soybean and subsequently removed, nitrogenase activity, nodulation, and nodule growth first decreased and then recovered. The relative amount of rhizobin A followed a similar pattern. Rhizobins were not detected in the roots, stems, and leaves of nodulated soybean plants. They were present in Lupinus nodules, but absent in alder nodules. PMID:16347004

  1. SOUTH SIDE OF SECOND STREET, LOOKING WESTSOUTHWEST FROM NORTH SIDE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SOUTH SIDE OF SECOND STREET, LOOKING WEST-SOUTHWEST FROM NORTH SIDE OF SECOND STREET NEAR INTERSECTION OF DOWELL AND SECOND STREETS - Pacific Coast Torpedo Station, Keyport Industrial District, Both sides of Second Street, between Dedrick Drive and Liberty Bay and one building west of Dedrick Drive and south of Second Street, Keyport, Kitsap County, WA

  2. SOUTH SIDE OF SECOND STREET, LOOKING WESTSOUTHWEST FROM NORTH SIDE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SOUTH SIDE OF SECOND STREET, LOOKING WEST-SOUTHWEST FROM NORTH SIDE OF SECOND STREET NEAR BUILDING 489 - Pacific Coast Torpedo Station, Keyport Industrial District, Both sides of Second Street, between Dedrick Drive and Liberty Bay and one building west of Dedrick Drive and south of Second Street, Keyport, Kitsap County, WA

  3. Night Side Jovian Aurora

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Jovian aurora on the night side of the planet. The upper bright arc is auroral emission seen 'edge on' above the planetary limb with the darkness of space as a background. The lower bright arc is seen against the dark clouds of Jupiter. The aurora is easier to see on the night side of Jupiter because it is fainter than the clouds when they are illuminated by sunlight. Jupiter's north pole is out of view to the upper right. The images were taken in the clear filter (visible light) and are displayed in shades of blue.

    As on Earth, the auroral emission is caused by electrically charged particles striking the upper atmosphere from above. The particles travel along the magnetic field lines of the planet, but their origin is not fully understood. The field lines where the aurora is most intense cross the Jovian equator at large distances (many Jovian radii) from the planet. The faint background throughout the image is scattered light in the camera. This stray light comes from the sunlit portion of Jupiter, which is out of the image to the right. In multispectral observations the aurora appears red, consistent with glow from atomic hydrogen in Jupiter's atmosphere. Galileo's unique perspective allows it to view the night side of the planet at short range, revealing details that cannot be seen from Earth. These detailed features are time dependent, and can be followed in sequences of Galileo images.

    North is at the top of the picture. A grid of planetocentric latitude and west longitude is overlain on the images. The images were taken on November 5, 1997 at a range of 1.3 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the

  4. Comparison of silatrane, phosphonic acid, and carboxylic acid functional groups for attachment of porphyrin sensitizers to TiO2 in photoelectrochemical cells.

    PubMed

    Brennan, Bradley J; Llansola Portolés, Manuel J; Liddell, Paul A; Moore, Thomas A; Moore, Ana L; Gust, Devens

    2013-10-21

    A tetra-arylporphyrin dye was functionalized with three different anchoring groups used to attach molecules to metal oxide surfaces. The physical, photophysical and electrochemical properties of the derivatized porphyrins were studied, and the dyes were then linked to mesoporous TiO2. The anchoring groups were β-vinyl groups bearing either a carboxylate, a phosphonate or a siloxy moiety. The siloxy linkages were made by treatment of the metal oxide with a silatrane derivative of the porphyrin. The surface binding and lability of the anchored molecules were studied, and dye performance was compared in a dye-sensitized solar cell (DSSC). Transient absorption spectroscopy was used to study charge recombination processes. At comparable surface concentration, the porphyrin showed comparable performance in the DSSC, regardless of the linker. However, the total surface coverage achievable with the carboxylate was about twice that obtainable with the other two linkers, and this led to higher current densities for the carboxylate DSSC. On the other hand, the carboxylate-linked dyes were readily leached from the metal oxide surface under alkaline conditions. The phosphonates were considerably less labile, and the siloxy-linked porphyrins were most resistant to leaching from the surface. The use of silatrane proved to be a practical and convenient way to introduce the siloxy linkages, which can confer greatly increased stability on dye-sensitized electrodes with photoelectrochemical performance comparable to that of the other linkers.

  5. The Effect of the Methylation and N-H Acidic Group on the Physicochemical Properties of Imidazolium-Based Ionic Liquids

    PubMed Central

    Rodrigues, Ana S.M.C.; Rocha, Marisa A. A.; Almeida, Hugo F. D.; Neves, Catarina M. S. S.; Lopes-da-Silva, José A.; Freire, Mara G.; Coutinho, João A. P.; Santos, Luís M. N. B. F.

    2017-01-01

    This work presents and highlights the differentiation of the physicochemical properties of the [C1Him][NTf2], [C2Him][NTf2], [1C12C1Him][NTf2], and [1C42C13C1im][NTf2] that are related with the strong bulk interaction potential, which highlights the differentiation on the physicochemical arising from the presence of the acidic group (N-H) as well as the methylation in position 2 (C(2)) of the imidazolium ring. Densities, viscosities, refractive indices and surface tensions in a wide range of temperatures, as well as, isobaric heat capacities at 298.15 K, for this IL series are presented and discussed. It was found that the volumetric properties are barely affected by the geometric and structural isomerization, following a quite regular trend. A linear correlation between the glass transition temperature, Tg, and the alkyl chain size was found; however, ILs with the acidic N-H group present a significant higher Tg than the [1CN-13C1im][NTf2] and [1CN3CNim][NTf2] series. It was found that the most viscous ILs, ([1C1Him][NTf2], [1C2Him][NTf2] and [1C12C1Him][NTf2]) have an acidic N-H group in the imidazolium ring in agreement with the observed increase of energy barrier of flow. The methylation in position 2, C(2), as well as, the N-H acidic group in the imidazolium ring, contribute to a significant variation in the cation-anion interactions and their dynamics, which is reflected in their charge distribution and polarizability leading to a significant differentiation of the refractive indices, surface tension and heat capacities. The observed differentiation of the physicochemical properties of the [1C1Him][NTf2], [1C2Him][NTf2], [1C12C1Him][NTf2], and [1C42C13C1im][NTf2] are an indication of the stronger bulk interaction potential, which highlights the effect that arises from the presence of the acidic group (N-H) as well as the methylation in position 2 of the imidazolium ring. PMID:26082427

  6. Managing Chemotherapy Side Effects: Pain

    MedlinePlus

    ... ational C ancer I nstitute Managing Chemotherapy Side Effects Pain It’s important to treat pain. If you ... to pay for pain medicine. Managing Chemotherapy Side Effects: Pain Keep track of the pain. Each day, ...

  7. Side to Side Esophagogastrojejunoplasty in Post-corrosive Stricture of Distal Esophagus and Proximal Stomach.

    PubMed

    Sharma, Praveen; Pancholi, Mukesh; Patel, Gulab; Sharma, Anju

    2015-12-01

    A four years old female child presented after 2 months of ingestion of battery fluid (sulfuric acid) accidently with stricture of the distal esophagus, esophagogastric junction, and fundus as well as proximal portion of the body of the stomach. Corrosive stricture involving the distal esophagus with the proximal stomach is not a frequently encountered condition. Side to side esophagogastrojejunostomy without removal of the strictured esophagus or stomach (side to side esophagogastrojejunoplasty) can be done in such patient hence preserving the stomach which is important physiologically as a reservoir and for the secretion of gastric juices. In review of literature in search engines like MD Consult, PubMed, Cochrane Library, and Embase and standard textbooks of surgery, we could not find such procedure had been performed till date, so that it is the innovative approach with support of literature and surgical principles.

  8. Novel Side-Chain Liquid Cyrstalline Polymers

    DTIC Science & Technology

    1989-01-01

    chloride was added, and the mixture was acidified with formic acid . The organic layer ..as separated, dried over anhydrous MgSO4, filtered and the...Polymers and Sequential Copolymers by Phase Transfer Catalysis , 29. Synthesis of Thermotropic Side-Chain Liquid Crystalline Polymers Containing a Poly(2,6...Western Reserve University) 00 6. C. Pugh and V. Percec Functional Polymers and Sequential Copolymers by Phase Transfer Catalysis . 30.-Synthesis of

  9. Human hepatoblastoma cells (HepG2) and rat hepatoma cells are defective in important enzyme activities in the oxidation of the C27 steroid side chain in bile acid formation.

    PubMed

    Farrants, A K; Nilsson, A; Pedersen, J I

    1993-12-01

    We have examined the ability of HepG2 human hepatoblastoma cells and 7800 C1 Morris rat hepatoma cells to convert 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid (THCA) and 3 alpha, 7 alpha-dihydroxy-5 beta-cholestanoic acid (DHCA) to cholic acid and chenodeoxycholic acid, respectively. Cell extracts from both these cell lines could neither form cholic acid from THCA nor from the activated form, THCA-CoA. This suggests that both cell lines are defective in two enzyme activities involved in the pathway, the microsomal THCA-CoA ligase and the peroxisomal THCA-CoA oxidase. Furthermore, we show that the subsequent enzymes are active in the conversion to bile acids, because the product of the THCA-CoA oxidase, 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholest-24-enoyl-coenzyme A (delta 24-THCA-CoA) or delta 24-THCA in the presence of THCA-CoA ligase, are converted to cholic acid by both cell lines. HepG2 cells were able to slowly form chenodeoxycholic acid and cholic acid from 5 beta-cholestane-3 alpha, 7 alpha-diol and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol, respectively, in 24- and 96-h incubations. The rate of cholic acid formation was lower than the rate for chenodeoxycholic acid and there was a clear accumulation of THCA. 7800 C1 Morris cells had no ability to form cholic acid or chenodeoxycholic acid after 96 h incubation. We conclude that these two cell lines have defects in two enzyme activities involved in the peroxisomal oxidation in bile acid formation, the microsomal THCA-CoA ligase and the peroxisomal THCA-CoA oxidase.

  10. A Naturally Occurring Single Amino Acid Replacement in Multiple Gene Regulator of Group A Streptococcus Significantly Increases Virulence

    PubMed Central

    Sanson, Misu; O'Neill, Brian E.; Kachroo, Priyanka; Anderson, Jeff R.; Flores, Anthony R.; Valson, Chandni; Cantu, Concepcion C.; Makthal, Nishanth; Karmonik, Christof; Fittipaldi, Nahuel; Kumaraswami, Muthiah; Musser, James M.; Olsen, Randall J.

    2016-01-01

    Single-nucleotide polymorphisms (SNPs) are the most common source of genetic variation within a species; however, few investigations demonstrate how naturally occurring SNPs may increase strain virulence. We recently used group A Streptococcus as a model pathogen to study bacteria strain genotype–patient disease phenotype relationships. Whole-genome sequencing of approximately 800 serotype M59 group A Streptococcus strains, recovered during an outbreak of severe invasive infections across North America, identified a disproportionate number of SNPs in the gene encoding multiple gene regulator of group A Streptococcus (mga). Herein, we report results of studies designed to test the hypothesis that the most commonly occurring SNP, encoding a replacement of arginine for histidine at codon 201 of Mga (H201R), significantly increases virulence. Whole transcriptome analysis revealed that the H201R replacement significantly increased expression of mga and 54 other genes, including many proven virulence factors. Compared to the wild-type strain, a H201R isogenic mutant strain caused significantly larger skin lesions in mice. Serial quantitative bacterial culture and noninvasive magnetic resonance imaging also demonstrated that the isogenic H201R strain was significantly more virulent in a nonhuman primate model of joint infection. These findings show that the H201R replacement in Mga increases the virulence of M59 group A Streptococcus and provide new insight to how a naturally occurring SNP in bacteria contributes to human disease phenotypes. PMID:25476528

  11. The effect of ω-fatty acids on the expression of phospholipase A2 group 2A in human gastric cancer patients

    PubMed Central

    Shariati, Mahboube; Aghaei, Mahmoud; Movahedian, Ahmad; Somi, Mohammad Hosein; Dolatkhah, Homayun; Aghazade, Ahmad Mirza

    2016-01-01

    Background: Studies show that polyunsaturated fatty acids (PUFAs) may have an inhibitory role in carcinogenesis. It was previously shown that PLA2 group 2A (PLA2G2A) messenger RNA (mRNA) expression is associated with less frequent metastasis and longer survival in gastric adenocarcinoma. This study intends to investigate the effect of PUFAs on the expression of PLA2G2A in patients with gastric cancer. Materials and Methods: Thirty-four patients with gastric cancer (GC) were randomly divided into two groups. The first group received cisplatin medication. The second group received cisplatin medication and supplements of ω-fatty acids for three courses. The total RNA was extracted from the tissues and cDNA was synthesized. The gene expression of PLA2G2A was evaluated by the real-time polymerase chain reaction (PCR) method. To confirm the changes in gene expression, frozen section was utilized. The frozen tissue samples were sectioned and stained using the immunohistochemistry technique. Results: After chemotherapy and chemotherapy plus supplement, the relative mean of PLA2G2A gene expression increased 1.5 ± 0.5-fold and 7.4 ± 2.6-fold, respectively (P = 0.006). The relative mean of gene expression in patients who received cisplatin and ω-fatty acids supplement increased more significantly (7.5 ± 3.3-fold) than in patients who received only cisplatin (P = 0.016). Conclusion: It was found that PUFAs increased the gene and protein expression of PLA2G2A in gastric cancer. Concerning the fact that studies reveal protective function of PLA2G2A in gastric cancer, it is suggested that increased expression of PLA2G2A is helpful. Furthermore, PUFAs can be considered as a useful therapeutic supplement for patients with gastric cancer. PMID:27904556

  12. Hyaluronic acid capsule modulates M protein-mediated adherence and acts as a ligand for attachment of group A Streptococcus to CD44 on human keratinocytes.

    PubMed Central

    Schrager, H M; Albertí, S; Cywes, C; Dougherty, G J; Wessels, M R

    1998-01-01

    We used wild-type and isogenic mutant strains of group A Streptococcus (GAS) that expressed M protein, capsule, or both to study the function of M protein and the hyaluronic acid capsular polysaccharide in attachment of GAS to human keratinocytes. Types 6 and 24, but not type 18, M protein were found to mediate attachment of GAS to soft palate or skin keratinocytes, but this interaction was prevented by the hyaluronic acid capsule on highly encapsulated, or mucoid, strains. Monoclonal antibody to CD44, the principal hyaluronic acid-binding receptor on keratinocytes, inhibited attachment of both highly encapsulated and poorly encapsulated wild type strains of GAS, but not the attachment of acapsular mutants. Transfection of K562 cells with cDNA encoding human CD44 conferred the capacity to bind each of six wild-type strains of GAS, but not to bind acapsular mutants. Because, in contrast to other potential adhesins, the group A streptococcal capsule is both highly conserved and surface-exposed, it may serve as a universal adhesin for attachment of diverse strains of GAS to keratinocytes of the pharyngeal mucosa and the skin. PMID:9541502

  13. Novel nanostructure amino acid-based poly(amide-imide)s enclosing benzimidazole pendant group in green medium: fabrication and characterization.

    PubMed

    Mallakpour, Shadpour; Dinari, Mohammad

    2012-10-01

    In the present work, several novel optically active nanostructure poly(amide-imide)s (PAI)s were synthesized via step-growth polymerization reaction of chiral diacids based on pyromellitic dianhydride-derived dicarboxylic acids containing different natural amino acids such as L-alanine, S-valine, L-leucine, L-isoleucine, L-methionine, and L-phenylalanine with 2-(3,5-diaminophenyl)-benzimidazole under green conditions using molten tetrabutylammonium bromide. The new optically active PAIs were achieved in good yields and moderate inherent viscosity up to 0.41 dL/g. The synthesized polymers were characterized with FT-IR, (1)H-NMR, X-ray diffraction, field emission scanning electron microscopy (FE-SEM), elemental and thermogravimetric analysis (TGA) techniques. These polymers show high solubility in organic polar solvents due to the presence of amino acid and benzimidazole pendant group at room temperature. FE-SEM results show that, these chiral nanostructured PAIs have spherical shapes and the particle size is around 20-80 nm. On the basis of TGA data, such PAIs are thermally stable and can be classified as self-extinguishing polymers. In addition due to the existence of amino acids in the polymer backbones, these macromolecules are not only optically active but also could be biodegradable and thus may well be classified under environmentally friendly materials.

  14. Fourth 3D structure of the chitosan molecule: conformation of chitosan in its salts with medical organic acids having a phenyl group.

    PubMed

    Kawahara, Makoto; Yui, Toshifumi; Oka, Kunio; Zugenmaier, Peter; Suzuki, Shiho; Kitamura, Shinichi; Okuyama, Kenji; Ogawa, Kozo

    2003-07-01

    Chitosan salts with two medical organic acids having phenyl groups (salicylic and gentisic acids) exhibited fiber diffraction patterns of a new type of crystal which does not compare with known types I and II. The crystals, called type III salts, showed a fiber repeat of 2.550 nm and a meridional reflection at the 5th layer line. These results coupled with a conformational analysis indicate the chain conformation of chitosan with the salts to be a 5/3 helix, this helix differing from those of type I (an extended two-fold helix) and type II (a relaxed two-fold helix or a 4/1 helix). The fiber patterns of all the type III salts were similar. This observation has also been found with type II salts and is an indication that the acid ions are not arranged in regular positions in the crystals. A comparison of solid-state 13C-NMR spectra of the gentisic acid salt and the aspirin salt, which could not be crystallized, suggests that, in the latter salt, the chitosan molecules also formed a 5/3 helix.

  15. Synthesis of quinoline derivatives containing pyrazole group and investigation of their crystal structure and spectroscopic properties in relation to acidity and alkalinity of mediums.

    PubMed

    Ren, Tiegang; Wang, Jie; Li, Guihui; Cheng, Hongbin; Li, Yongzhe

    2014-08-14

    Two series of quinoline derivatives containing pyrazole group were synthesized and characterized by means of (1)H NMR, FT-IR, MS, elemental analysis and X-ray single crystal diffraction, and their UV-vis absorption behavior and fluorescence properties were also measured. Moreover, the effects of acetic acid and triethylamine on the spectroscopic properties of synthesized products were examined with compounds 3a and 5a as examples. It has been found that all synthesized quinoline derivatives show maximum absorption peak at 303 nm and emission peaks around 445 nm. Besides, both acetic acid and triethylamine can change the acidity of the medium, thereby influencing the UV-vis absorption spectra and fluorescence spectra of synthesized products. Moreover, theoretical investigations indicate that the integration of H(+) and N atom of quinoline ring favors the formation of a new product in the presence of acetic acid, and the product obtained in this case shows a new UV-vis absorption peak at 400 nm.

  16. Synthesis of quinoline derivatives containing pyrazole group and investigation of their crystal structure and spectroscopic properties in relation to acidity and alkalinity of mediums

    NASA Astrophysics Data System (ADS)

    Ren, Tiegang; Wang, Jie; Li, Guihui; Cheng, Hongbin; Li, Yongzhe

    2014-08-01

    Two series of quinoline derivatives containing pyrazole group were synthesized and characterized by means of 1H NMR, FT-IR, MS, elemental analysis and X-ray single crystal diffraction, and their UV-vis absorption behavior and fluorescence properties were also measured. Moreover, the effects of acetic acid and triethylamine on the spectroscopic properties of synthesized products were examined with compounds 3a and 5a as examples. It has been found that all synthesized quinoline derivatives show maximum absorption peak at 303 nm and emission peaks around 445 nm. Besides, both acetic acid and triethylamine can change the acidity of the medium, thereby influencing the UV-vis absorption spectra and fluorescence spectra of synthesized products. Moreover, theoretical investigations indicate that the integration of H+ and N atom of quinoline ring favors the formation of a new product in the presence of acetic acid, and the product obtained in this case shows a new UV-vis absorption peak at 400 nm.

  17. Energetic, Structural, and Antimicrobial Analyses of [beta]-Lactam Side Chain Recognition by [beta]-Lactamases

    SciTech Connect

    Caselli, E.; Powers, R.A.; Blaszczak, L.C.; Wu, C.Y.E.; Prati, F.; Shoichet, B.K.

    2010-03-05

    Penicillins and cephalosporins are among the most widely used and successful antibiotics. The emergence of resistance to these {beta}-lactams, most often through bacterial expression of {beta}-lactamases, threatens public health. To understand how {beta}-lactamases recognize their substrates, it would be helpful to know their binding energies. Unfortunately, these have been difficult to measure because {beta}-lactams form covalent adducts with {beta}-lactamases. This has complicated functional analyses and inhibitor design. To investigate the contribution to interaction energy of the key amide (R1) side chain of {beta}-lactam antibiotics, eight acylglycineboronic acids that bear the side chains of characteristic penicillins and cephalosporins, as well as four other analogs, were synthesized. These transition-state analogs form reversible adducts with serine {beta}-lactamases. Therefore, binding energies can be calculated directly from K{sub i} values. The K{sub i} values measured span four orders of magnitude against the Group I {beta}-lactamase AmpC and three orders of magnitude against the Group II {beta}-lactamase TEM-1. The acylglycineboronic acids have K{sub i} values as low as 20 nM against AmpC and as low as 390 nM against TEM-1. The inhibitors showed little activity against serine proteases, such as chymotrypsin. R1 side chains characteristic of {beta}-lactam inhibitors did not have better affinity for AmpC than did side chains characteristic of {beta}-lactam substrates. Two of the inhibitors reversed the resistance of pathogenic bacteria to {beta}-lactams in cell culture. Structures of two inhibitors in their complexes with AmpC were determined by X-ray crystallography to 1.90 {angstrom} and 1.75 {angstrom} resolution; these structures suggest interactions that are important to the affinity of the inhibitors. Acylglycineboronic acids allow us to begin to dissect interaction energies between {beta}-lactam side chains and {beta}-lactamases. Surprisingly

  18. E-Group Arrangements

    NASA Astrophysics Data System (ADS)

    Aylesworth, Grant R.

    Group E at Uaxactún has long been considered an ancient Maya observatory in which an observer could see the sun rise along architectural alignments at the solstices and equinoxes. E-Groups named for the architectural complex list identified in Group E at Uaxactún, typically consist of a large radial pyramid on their west side and three temples on a raised platform on their east side.

  19. The influence of surface oxygen and hydroxyl groups on the dehydrogenation of ethylene, acetic acid and hydrogenated vinyl acetate on pure Pd(1 0 0): A DFT study

    NASA Astrophysics Data System (ADS)

    Huang, Yanping; Dong, Xiuqin; Yu, Yingzhe; Zhang, Minhua

    2016-12-01

    On the basis of a Langmuir-Hinshelwood-type mechanism, the dehydrogenation of ethylene, acetic acid and hydrogenated vinyl acetate (VAH) on pure Pd(1 0 0) with surface oxygen atoms (Os) and hydroxyl groups (OHs) was studied with density functional theory (DFT) method. Our calculation results show that both Os and OHs can consistently reduce the activation energies of dehydrogenation of ethylene, acetic acid and VAH to some degree with only one exception that OHs somehow increase the activation energy of VAH. Based on Langmuir-Hinshelwood mechanism, the three dehydrogenation reactions in presence of surface Os and OHs are almost consistently favored, compared with the corresponding processes on clean Pd(1 0 0) surfaces, and thus a Langmuir-Hinshelwood-type mechanism may not be excluded beforehand when investigating the microscopic performance of the oxygen-assisted vinyl acetate synthesis on Pd(1 0 0) catalysts.

  20. Electron-Withdrawing Trifluoromethyl Groups in Combination with Hydrogen Bonds in Polyols: Brønsted Acids, Hydrogen-Bond Catalysts, and Anion Receptors

    SciTech Connect

    Shokri, Alireza; Wang, Xue B.; Kass, Steven R.

    2013-06-26

    Electron withdrawing trifluoromethyl groups were characterized in combination with hydrogen bond interactions in three polyols (i.e., CF3CH(OH)CH2CH(OH)CF3, 1; (CF3)2C(OH)C(OH)(CF3)2, 2; ((CF3)2C(OH)CH2)2CHOH, 3) by pKa measurements in DMSO and H2O, negative ion photoelectron spectroscopy and binding constant determinations with Cl–. Their catalytic behavior in several reactions were also examined and compared to a BrØnsted acid (HOAc) and a commonly employed thiourea ((3,5-(CF3)3C6H3NH)2CS). The combination of inductive stabilization and hydrogen bonds was found to afford potent acids which are effective catalysts. It also appears that hydrogen bonds can transmit the inductive effect over distance even in an aqueous environment, and this has far reaching implications.

  1. Comparison of Efficacy of Side to Side Versus End to Side Arteriovenous Fistulae Formation in Chronic Renal Failure as a Permanent Hemodialysis Access

    PubMed Central

    Mozaffar, Mohammad; Fallah, Mahtab; Lotfollahzadeh, Saran; Sobhiyeh, Mohammad Reza; Gholizadeh, Barmak; Jabbehdari, Sayena; Mahdi, Zeinab

    2013-01-01

    Background In candidate patients for permanent hemodialysis or dialysis on a regular basis, an appropriate vascular access has great importance. The best permanent access is AVF (arterio venous fistula). Use of a technique to create AVF with better patency seems to be logical. Objectives The present study aimed to compare the efficacy rate of AVFs using two different anastomosis methods; Side to Side (STS) versus End to Side (ETS) and to determine whether the different approaches render any preferences or complications. Patients and Methods Sixty end stage renal disease (ESRD) patients were included in this clinical trial in two assigned groups of 30 patients. In one group end to side method to create AVF was used while in the other group Side to Side technique was applied for access in surgery. Both groups were followed for duration of 6 months to assess patency. For evaluating the quantitive variables, t-test was used while qualitative variables were measured using the chi-square and Fisher`s exact tests. Results In the 6 months duration, 6 patients (20%) in the STS (side to side) group and 5 patients (16.6%) in the ETS (end to side) group experienced a non-functional AVF. In the ETS group the failure was generally a result of thrombosed access while in the STS group, 4 out of 6 patients with complications, experienced thrombosis while the other 2 patients had venous hypertension. The total failure rate was 18.3% and during the 6 months of follow up no significant difference was detected in the efficacy rate. Nevertheless, in case of longer follow ups, different outcomes could be seen. Conclusions This study demonstrated that there was no significant statistical difference between the functional patency rates of fistulae placed by STS or ETS methods. PMID:24282794

  2. Improvement of oxygen-containing functional groups on olive stones activated carbon by ozone and nitric acid for heavy metals removal from aqueous phase.

    PubMed

    Bohli, Thouraya; Ouederni, Abdelmottaleb

    2016-08-01

    Recently, modification of surface structure of activated carbons in order to improve their adsorption performance toward especial pollutants has gained great interest. Oxygen-containing functional groups have been devoted as the main responsible for heavy metal binding on the activated carbon surface; their introduction or enhancement needs specific modification and impregnation methods. In the present work, olive stones activated carbon (COSAC) undergoes surface modifications in gaseous phase using ozone (O3) and in liquid phase using nitric acid (HNO3). The activated carbon samples were characterized using N2 adsorption-desorption isotherm, SEM, pHpzc, FTIR, and Boehm titration. The activated carbon parent (COSAC) has a high surface area of 1194 m(2)/g and shows a predominantly microporous structure. Oxidation treatments with nitric acid and ozone show a decrease in both specific surface area and micropore volumes, whereas these acidic treatments have led to a fixation of high amount of surface oxygen functional groups, thus making the carbon surface more hydrophilic. Activated carbon samples were used as an adsorbent matrix for the removal of Co(II), Ni(II), and Cu(II) heavy metal ions from aqueous solutions. Adsorption isotherms were obtained at 30 °C, and the data are well fitted to the Redlich-Peterson and Langmuir equation. Results show that oxidized COSACs, especially COSAC(HNO3), are capable to remove more Co(II), Cu(II), and Ni(II) from aqueous solution. Nitric acid-oxidized olive stones activated carbon was tested in its ability to remove metal ions from binary systems and results show an important maximum adsorbed amount as compared to single systems.

  3. A united physicochemical description of the protonation and metal ion complexation equilibria of natural organic acids (humic and fulvic acids). 2. Influence of polyelectrolyte properties and functional group heterogeneity on the protonation equilibria of fulvic acid

    USGS Publications Warehouse

    Ephraim, J.; Alegret, S.; Mathuthu, A.; Bicking, M.; Malcolm, R.L.; Marinsky, J.A.

    1986-01-01

    Potentiometric studies of the neutralization of several fulvic acid sources with standard base in aqueous and nonaqueous media have been conducted. Analysis of the results with a recently developed unified physicochemical model has shown that the protonation behavior of these fulvic acid sources is a reflection of (1) their polyelectrolyte nature and (2) their heterogeneity. It has been possible to ascribe the polyelectrolyte properties observed to a rather inflexible fulvic acid molecule whose variably charged surface is impermeable to simple electrolyte. ?? 1986 American Chemical Society.

  4. Structural and Functional Studies of a Newly Grouped Haloquadratum walsbyi Bacteriorhodopsin Reveal the Acid-resistant Light-driven Proton Pumping Activity.

    PubMed

    Hsu, Min-Feng; Fu, Hsu-Yuan; Cai, Chun-Jie; Yi, Hsiu-Pin; Yang, Chii-Shen; Wang, Andrew H-J

    2015-12-04

    Retinal bound light-driven proton pumps are widespread in eukaryotic and prokaryotic organisms. Among these pumps, bacteriorhodopsin (BR) proteins cooperate with ATP synthase to convert captured solar energy into a biologically consumable form, ATP. In an acidic environment or when pumped-out protons accumulate in the extracellular region, the maximum absorbance of BR proteins shifts markedly to the longer wavelengths. These conditions affect the light-driven proton pumping functional exertion as well. In this study, wild-type crystal structure of a BR with optical stability under wide pH range from a square halophilic archaeon, Haloquadratum walsbyi (HwBR), was solved in two crystal forms. One crystal form, refined to 1.85 Å resolution, contains a trimer in the asymmetric unit, whereas another contains an antiparallel dimer was refined at 2.58 Å. HwBR could not be classified into any existing subgroup of archaeal BR proteins based on the protein sequence phylogenetic tree, and it showed unique absorption spectral stability when exposed to low pH values. All structures showed a unique hydrogen-bonding network between Arg(82) and Thr(201), linking the BC and FG loops to shield the retinal-binding pocket in the interior from the extracellular environment. This result was supported by R82E mutation that attenuated the optical stability. The negatively charged cytoplasmic side and the Arg(82)-Thr(201) hydrogen bond may play an important role in the proton translocation trend in HwBR under acidic conditions. Our findings have unveiled a strategy adopted by BR proteins to solidify their defenses against unfavorable environments and maintain their optical properties associated with proton pumping.

  5. Structural and Functional Studies of a Newly Grouped Haloquadratum walsbyi Bacteriorhodopsin Reveal the Acid-resistant Light-driven Proton Pumping Activity*

    PubMed Central

    Hsu, Min-Feng; Fu, Hsu-Yuan; Cai, Chun-Jie; Yi, Hsiu-Pin; Yang, Chii-Shen; Wang, Andrew H.-J.

    2015-01-01

    Retinal bound light-driven proton pumps are widespread in eukaryotic and prokaryotic organisms. Among these pumps, bacteriorhodopsin (BR) proteins cooperate with ATP synthase to convert captured solar energy into a biologically consumable form, ATP. In an acidic environment or when pumped-out protons accumulate in the extracellular region, the maximum absorbance of BR proteins shifts markedly to the longer wavelengths. These conditions affect the light-driven proton pumping functional exertion as well. In this study, wild-type crystal structure of a BR with optical stability under wide pH range from a square halophilic archaeon, Haloquadratum walsbyi (HwBR), was solved in two crystal forms. One crystal form, refined to 1.85 Å resolution, contains a trimer in the asymmetric unit, whereas another contains an antiparallel dimer was refined at 2.58 Å. HwBR could not be classified into any existing subgroup of archaeal BR proteins based on the protein sequence phylogenetic tree, and it showed unique absorption spectral stability when exposed to low pH values. All structures showed a unique hydrogen-bonding network between Arg82 and Thr201, linking the BC and FG loops to shield the retinal-binding pocket in the interior from the extracellular environment. This result was supported by R82E mutation that attenuated the optical stability. The negatively charged cytoplasmic side and the Arg82–Thr201 hydrogen bond may play an important role in the proton translocation trend in HwBR under acidic conditions. Our findings have unveiled a strategy adopted by BR proteins to solidify their defenses against unfavorable environments and maintain their optical properties associated with proton pumping. PMID:26483542

  6. Recruitment of SH-containing peptides to lipid and biological membranes through the use of a palmitic acid functionalized with a maleimide group.

    PubMed

    Haralampiev, Ivan; Mertens, Monique; Schwarzer, Roland; Herrmann, Andreas; Volkmer, Rudolf; Wessig, Pablo; Müller, Peter

    2015-01-02

    This study presents a novel and easily applicable approach to recruit sulfhydryl-containing biomolecules to membranes by using a palmitic acid which is functionalized with a maleimide group. Notably, this strategy can also be employed with preformed (biological) membranes. The applicability of the assay is demonstrated by characterizing the binding of a Rhodamine-labeled peptide to lipid and cellular membranes using methods of fluorescence spectroscopy, lifetime measurement, and microscopy. Our approach offers new possibilities for preparing biologically active liposomes and manipulating living cells.

  7. One-electron oxidation of 2-(4-methoxyphenyl)-2-methylpropanoic and 1-(4-methoxyphenyl)cyclopropanecarboxylic acids in aqueous solution. the involvement of radical cations and the influence of structural effects and pH on the side-chain fragmentation reactivity.

    PubMed

    Bietti, Massimo; Capone, Alberto

    2008-01-18

    A product and time-resolved kinetic study on the one-electron oxidation of 2-(4-methoxyphenyl)-2-methylpropanoic acid (2), 1-(4-methoxyphenyl)cyclopropanecarboxylic acid (3), and of the corresponding methyl esters (substrates 4 and 5, respectively) has been carried out in aqueous solution. With 2, no direct evidence for the formation of an intermediate radical cation 2*+ but only of the decarboxylated 4-methoxycumyl radical has been obtained, indicating either that 2*+ is not formed or that its decarboxylation is too fast to allow detection under the experimental conditions employed (k > 1 x 10(7) s(-1)). With 3, oxidation leads to the formation of the corresponding radical cation 3*+ or radical zwitterion -3*+ depending on pH. At pH 1.0 and 6.7, 3*+ and -3*+ have been observed to undergo decarboxylation as the exclusive side-chain fragmentation pathway with rate constants k = 4.6 x 10(3) and 2.3 x 10(4) s(-1), respectively. With methyl esters 4 and 5, direct evidence for the formation of the corresponding radical cations 4*+ and 5*+ has been obtained. Both radical cations have been observed to display a very low reactivity and an upper limit for their decay rate constants has been determined as k < 10(3) s(-1). Comparison between the one-electron oxidation reactions of 2 and 3 shows that the replacement of the C(CH3)2 moiety with a cyclopropyl group determines a decrease in decarboxylation rate constant of more than 3 orders of magnitude. This large difference in reactivity has been qualitatively explained in terms of three main contributions: substrate oxidation potential, stability of the carbon-centered radical formed after decarboxylation, and stereoelectronic effects. In basic solution, -3*+ and 5*+ have been observed to react with -OH in a process that is assigned to the -OH-induced ring-opening of the cyclopropane ring, and the corresponding second-order rate constants (k-OH) have been obtained. With -3*+, competition between decarboxylation and -OH

  8. Characterization of N-terminal amino group-heme ligation emerging upon guanidine hydrochloric acid induced unfolding of Hydrogenobacter thermophilus ferricytochrome c552.

    PubMed

    Tai, Hulin; Kawano, Shin; Yamamoto, Yasuhiko

    2008-01-01

    Nonnative heme coordination structures emerging upon guanidine hydrochloric acid (GdnHCl) induced unfolding of Hydrogenobacter thermophilus ferricytochrome c552 were characterized by means of paramagnetic NMR. The heme coordination structure possessing the N-terminal amino group of the peptide chain in place of axial Met (His-Nterm form) was determined in the presence of GdnHCl concentrations in excess of 1.5 M at neutral pH. The stability of the His-Nterm form at pH 7.0 was found to be comparable with that of the bis-His form which has been recognized as a major nonnative heme coordination structure in cytochrome c folding/unfolding. Consequently, in addition to the bis-His form, the His-Nterm form is a substantial intermediate which affects the pathway and kinetics of the folding/unfolding of cytochromes c, of which the N-terminal amino groups are not acetylated.

  9. Activation and cleavage of the N-N bond in side-on bound [L₂M-NN-ML₂] (L = NH₂, NMe₂, N(i)Pr₂, C₅H₅, C₅Me₄H) dinitrogen complexes of transition metals from groups 4 through 9.

    PubMed

    Cavigliasso, Germán; Wilson, Laurence; McAlpine, Sarlae; Attar, Mariam; Stranger, Robert; Yates, Brian F

    2010-05-21

    The activation and cleavage of the N-N bond in side-on bound [L₂M-NN-ML₂] (L = NH₂, NMe₂, N(i)Pr₂, C₅H₅, C₅Me₄H) dinitrogen complexes of transition metals in groups 4 through 9 have been investigated using density functional theory. Emphasis has been placed on Ti, Zr, and Hf (group 4) complexes due to their experimental relevance. Calculations on these species have shown that for cases when the structural configuration corresponds to the terminal [ML₂] fragments adopting a perpendicular orientation with respect to the central [N-N] unit, a considerably higher degree of N-N activation is predicted relative to that observed in the experimentally characterized cyclopentadienyl analogues and in related systems involving end-on dinitrogen coordination. An examination of the orbital interactions between the metal-based fragments and the dinitrogen unit shows that both σ and π bonding are important in the side-on binding mode, in contrast to the end-on mode where metal-nitrogen π interactions are dominant. This analysis also reveals that the model amide systems possess the orbital properties identified as necessary for successful N-N hydrogenation. A significant result obtained for the amide complexes containing metals from groups 5 (V, Nb, Ta), 6 (Cr, Mo, W), and 7 (Mn, Tc, Re), is the presence of metal-metal bonding in configurations that are considerably distorted from planarity. As a consequence, these complexes exhibit strongly enhanced stability relative to species where metal-metal bonding is absent. In contrast, the d² metal-based configurations in the group 4 complexes of Ti, Zr, and Hf are unable to provide the six electrons required for complete reductive cleavage of the dinitrogen unit which is necessary to allow the metal centres to approach one another sufficiently for metal-metal bond formation.

  10. The DarkSide awakens

    NASA Astrophysics Data System (ADS)

    Davini, S.; Agnes, P.; Agostino, L.; Albuquerque, I. F. M.; Alexander, T.; Alton, A. K.; Arisaka, K.; Back, H. O.; Baldin, B.; Biery, K.; Bonfini, G.; Bossa, M.; Bottino, B.; Brigatti, A.; Brodsky, J.; Budano, F.; Bussino, S.; Cadeddu, M.; Cadonati, L.; Cadoni, M.; Calaprice, F.; Canci, N.; Candela, A.; Cao, H.; Cariello, M.; Carlini, M.; Catalanotti, S.; Cavalcante, P.; Chepurnov, A.; Cocco, A. G.; Covone, G.; D'Angelo, D.; D'Incecco, M.; De Cecco, S.; De Deo, M.; De Vincenzi, M.; Derbin, A.; Devoto, A.; Di Eusanio, F.; Di Pietro, G.; Edkins, E.; Empl, A.; Fan, A.; Fiorillo, G.; Fomenko, K.; Foster, G.; Franco, D.; Gabriele, F.; Galbiati, C.; Giganti, C.; Goretti, A. M.; Granato, F.; Grandi, L.; Gromov, M.; Guan, M.; Guardincerri, Y.; Hackett, B. R.; Herner, K. R.; Hungerford, E. V.; Ianni, Aldo; Ianni, Andrea; James, I.; Jollet, C.; Keeter, K.; Kendziora, C. L.; Kobychev, V.; Koh, G.; Korablev, D.; Korga, G.; Kubankin, A.; Li, X.; Lissia, M.; Lombardi, P.; Luitz, S.; Ma, Y.; Machulin, I. N.; Mandarano, A.; Mari, S. M.; Maricic, J.; Marini, L.; Martoff, C. J.; Meregaglia, A.; Meyers, P. D.; Miletic, T.; Milincic, R.; Montanari, D.; Monte, A.; Montuschi, M.; Monzani, M. E.; Mosteiro, P.; Mount, B. J.; Muratova, V. N.; Musico, P.; Napolitano, J.; Orsini, M.; Ortica, F.; Pagani, L.; Pallavicini, M.; Pantic, E.; Parmeggiano, S.; Pelczar, K.; Pelliccia, N.; Perasso, S.; Pocar, A.; Pordes, S.; Pugachev, D. A.; Qian, H.; Randle, K.; Ranucci, G.; Razeto, A.; Reinhold, B.; Renshaw, A. L.; Romani, A.; Rossi, B.; Rossi, N.; Rountree, S. D.; Sablone, D.; Saggese, P.; Saldanha, R.; Sands, W.; Sangiorgio, S.; Savarese, C.; Segreto, E.; Semenov, D. A.; Shields, E.; Singh, P. N.; Skorokhvatov, M. D.; Smirnov, O.; Sotnikov, A.; Stanford, C.; Suvorov, Y.; Tartaglia, R.; Tatarowicz, J.; Testera, G.; Tonazzo, A.; Trinchese, P.; Unzhakov, E. V.; Vishneva, A.; Vogelaar, B.; Wada, M.; Walker, S.; Wang, H.; Wang, Y.; Watson, A. W.; Westerdale, S.; Wilhelmi, J.; Wojcik, M. M.; Xiang, X.; Xu, J.; Yang, C.; Yoo, J.; Zavatarelli, S.; Zec, A.; Zhong, W.; Zhu, C.; Zuzel, G.

    2016-05-01

    The DarkSide program at LNGS aims to perform background-free WIMP searches using two phase liquid argon time projection chambers, with the ultimate goal of covering all parameters down to the so-called neutrino floor. One of the distinct features of the program is the use of underground argon with has a reduced content of the radioactive 39Ar compared to atmospheric argon. The DarkSide Collaboration is currently operating the DarkSide-50 experiment, the first such WIMP detector using underground argon. Operations with underground argon indicate a suppression of 39Ar by a factor (1.4 ± 0.2) × 103 relative to atmospheric argon. The new results obtained with DarkSide-50 and the plans for the next steps of the DarkSide program, the 20t fiducial mass DarkSide-20k detector and the 200 t fiducial Argo, are reviewed in this proceedings.

  11. Proton-bridge motions in amine conjugate acid ions having intramolecular hydrogen bonds to hydroxyl and amine groups.

    PubMed

    Ung, Hou U; Moehlig, Aaron R; Khodagholian, Sevana; Berden, Giel; Oomens, Jos; Morton, Thomas Hellman

    2013-02-14

    Vibrational spectra of two gaseous cations having NH···O intramolecular ionic hydrogen bonds and of nine protonated di- and polyamines having NH···N internal proton bridges, recorded using IR Multiple Photon Dissociation (IRMPD) of mass-selected ions, are reported. The band positions of hydroxyl stretching frequencies do not shift when a protonated amine becomes hydrogen bonded to oxygen. In three protonated diamines, lower frequency bands (550-650 cm(-1)) disappear upon isotopic substitution, as well as several bands in the 1100-1350 cm(-1) region. By treating the internal proton bridge as a linear triatomic, theory assigns the lowest frequency bands to N-H···N asymmetric stretches. A 2-dimensional model, based on quantization on a surface fit to points calculated using a double hybrid functional B2-P3LYP/cc-pVTZ//B3LYP/6-31G**, predicts their positions accurately. In at least one case, the conjugate acid of 1,5-cis-bis(dimethylamino)cyclooctane, a N-H···N bend shows up in the domain predicted by DFT normal mode calculations, but in most other cases the observed bands have frequencies 20-25% lower than expected for bending vibrations. Protonated Me(2)NCH(2)CMe(2)CH(2)CH(2)CH(2)NMe(2) shows three well-resolved bands at 620, 1200, and 1320 cm(-1), of which the lowest can be assigned to the asymmetric stretch. Other ions observed include doubly protonated 1,2,4,5-(Me(2)NCH(2))(4)-benzene and 1,2,4-(Me(2)NCH(2))(3)-benzene-5-CH(2)OH. Apart from the aforementioned rigid ion derived from the alicyclic diamine, the other ions enjoy greater conformational mobility, and coupling to low-frequency C-C bond torsions may account for the shift of vibrations with N-H···N character to lower frequencies. Low-barrier hydrogen bonding (LBHB) accounts for the fact that N-H···N asymmetric stretching vibrations of near linear proton bridges occur at frequencies below 650 cm(-1).

  12. Catechol Groups Enable Reactive Oxygen Species Scavenging-Mediated Suppression of PKD-NFkappaB-IL-8 Signaling Pathway by Chlorogenic and Caffeic Acids in Human Intestinal Cells.

    PubMed

    Shin, Hee Soon; Satsu, Hideo; Bae, Min-Jung; Totsuka, Mamoru; Shimizu, Makoto

    2017-02-20

    Chlorogenic acid (CHA) and caffeic acid (CA) are phenolic compounds found in coffee, which inhibit oxidative stress-induced interleukin (IL)-8 production in intestinal epithelial cells, thereby suppressing serious cellular injury and inflammatory intestinal diseases. Therefore, we investigated the anti-inflammatory mechanism of CHA and CA, both of which inhibited hydrogen peroxide (H₂O₂)-induced IL-8 transcriptional activity. They also significantly suppressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcriptional activity, nuclear translocation of the p65 subunit, and phosphorylation of IκB kinase (IKK). Additionally, upstream of IKK, protein kinase D (PKD) was also suppressed. Finally, we found that they scavenged H₂O₂-induced reactive oxygen species (ROS) and the functional moiety responsible for the anti-inflammatory effects of CHA and CA was the catechol group. Therefore, we conclude that the presence of catechol groups in CHA and CA allows scavenging of intracellular ROS, thereby inhibiting H₂O₂-induced IL-8 production via suppression of PKD-NF-κB signaling in human intestinal epithelial cells.

  13. Muscle antioxidant (vitamin E) and major fatty acid groups, lipid oxidation and retail colour of meat from lambs fed a roughage based diet with flaxseed or algae.

    PubMed

    Ponnampalam, Eric N; Burnett, Viv F; Norng, Sorn; Hopkins, David L; Plozza, Tim; Jacobs, Joe L

    2016-01-01

    The effect of feeding flaxseed or algae supplements to lambs on muscle antioxidant potential (vitamin E), major fatty acid groups, lipid oxidation and retail colour was investigated. Lambs (n=120) were randomly allocated to one of 4 dietary treatments according to liveweight and fed the following diets for eight weeks: Annual ryegrass hay [60%]+subterranean clover hay [40%] pellets=Basal diet; Basal diet with flaxseed (10.7%)=Flax; Basal diet with algae (1.8%)=Algae; Basal diet with flaxseed (10.7%) and algae (1.8%)=FlaxAlgae. Flaxseed or algae supplementation significantly affected major fatty acid groups in muscle. The addition of algae (average of Algae and FlaxAlgae) resulted in lower vitamin E concentration in muscle (P<0.003; 1.0 vs 1.3mg/kg of muscle) compared with lambs fed a diet without algae (average of Basal and Flax). Increasing muscle EPA+DHA by algae supplementation significantly increased lipid oxidation, but retail display colour of fresh meat was not affected.

  14. Catechol Groups Enable Reactive Oxygen Species Scavenging-Mediated Suppression of PKD-NFkappaB-IL-8 Signaling Pathway by Chlorogenic and Caffeic Acids in Human Intestinal Cells

    PubMed Central

    Shin, Hee Soon; Satsu, Hideo; Bae, Min-Jung; Totsuka, Mamoru; Shimizu, Makoto

    2017-01-01

    Chlorogenic acid (CHA) and caffeic acid (CA) are phenolic compounds found in coffee, which inhibit oxidative stress-induced interleukin (IL)-8 production in intestinal epithelial cells, thereby suppressing serious cellular injury and inflammatory intestinal diseases. Therefore, we investigated the anti-inflammatory mechanism of CHA and CA, both of which inhibited hydrogen peroxide (H2O2)-induced IL-8 transcriptional activity. They also significantly suppressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcriptional activity, nuclear translocation of the p65 subunit, and phosphorylation of IκB kinase (IKK). Additionally, upstream of IKK, protein kinase D (PKD) was also suppressed. Finally, we found that they scavenged H2O2-induced reactive oxygen species (ROS) and the functional moiety responsible for the anti-inflammatory effects of CHA and CA was the catechol group. Therefore, we conclude that the presence of catechol groups in CHA and CA allows scavenging of intracellular ROS, thereby inhibiting H2O2-induced IL-8 production via suppression of PKD-NF-κB signaling in human intestinal epithelial cells. PMID:28230729

  15. PACIFIC NORTHWEST SIDE-BY-SIDE PROTOCOL COMPARISON TEST

    EPA Science Inventory

    Eleven state, tribal, and federal agencies participated during summer 2005 in a side-by-side comparison of protocols used to measure common in-stream physical attributes to help determine which protocols are best for determining status and trend of stream/watershed condition. Th...

  16. View northeast, west side, and south side (showing National Defense ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View northeast, west side, and south side (showing National Defense University Academic Operations Center Building in background) - Fort McNair, Film Store House, Fort Lesley J. McNair, P Street between Third & Fourth Streets, Southwest, Washington, District of Columbia, DC

  17. 3. VIEW OF INTERIOR, EAST SIDE (SIDE A) OF BUILDING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW OF INTERIOR, EAST SIDE (SIDE A) OF BUILDING 883. INSTALLATION OF EQUIPMENT FOR THE MOLTEN SALT BATHS AND ROLLING MILLS PROCESSES. (4/25/57) - Rocky Flats Plant, Uranium Rolling & Forming Operations, Southeast section of plant, southeast quadrant of intersection of Central Avenue & Eighth Street, Golden, Jefferson County, CO

  18. Recent developments in fetal nucleic acids in maternal plasma: implications to noninvasive prenatal fetal blood group genotyping.

    PubMed

    Lo, Y M D

    2006-01-01

    The discovery of circulating cell-free fetal DNA in maternal plasma has opened up new possibilities for noninvasive prenatal diagnosis. Fetal DNA in maternal plasma has been used for the noninvasive prenatal determination of the RhD status of fetuses carried by RhD-negative pregnant women. In such analysis, the possible need of an internal control for the presence of detectable amounts of fetal DNA in a particular maternal plasma sample has been actively discussed. Recently, the development of a robust method for discriminating single nucleotide differences in plasma DNA using single allele base extension reaction (SABER) followed by matrix-assisted laser-desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) has opened up the possibilities of using a panel of single nucleotide polymorphisms as such a positive control. A second approach is the recent successful development of fetal epigenetic markers which can be developed into universal fetal DNA markers. These developments hold promise to allow the eventual widespread utilization of maternal plasma DNA analysis for the noninvasive prenatal diagnosis of blood group mismatches between the mother and fetus.

  19. Sorbents based on asbestos with a layer of an hydroxyethylcyclam derivative of PVC containing aquacomplexes of sulfuric acid or sodium hydroxide with aza-crown groups

    NASA Astrophysics Data System (ADS)

    Tsivadze, A. Yu.; Fridman, A. Ya.; Morozova, E. M.; Sokolova, N. P.; Voloshchuk, A. M.; Petukhova, G. A.; Bardyshev, I. I.; Gorbunov, A. M.; Polyakova, I. Ya.; Titova, V. N.; Yavich, A. A.; Novikov, A. K.; Petrova, N. V.

    2016-07-01

    Aquacomplexes of sulfuric acid and sodium hydroxide with aza-crown groups are synthesized in cavities of a sorbent from the porous layer of a PVC cyclam-derivative grafted onto fibers of asbestos fabric. The structure of sorbents with complexes is studied and their adsorption characteristics are determined. It is shown that the affinity of the developed surface toward ethanol, benzene, and hexane depends on the nature of complexes in the pore walls, and the volume of cavities formed as a result of the pores on the developed asbestos surface being coated with networks of aza-crown groups is larger than that of cavities with walls of aza-crown groups in the layers of a PVC cyclam derivative. Indicators of H+- and OH--conductivity of sorbents with complexes as electrochemical bridges are determined. It is shown that the major part of H+- and OH--ions moves through complexes with aza-crown groups in the region of cavities formed of pores on the surface of asbestos.

  20. Comparison the effectiveness of pyruvic acid 50% and salicylic acid 30% in the treatment of acne

    PubMed Central

    Jaffary, Fariba; Faghihi, Gita; Saraeian, Sara; Hosseini, Sayed Mohsen

    2016-01-01

    Background: Acne vulgaris is a chronic inflammatory disease of the pilosebaceous follicles and one of the most common skin diseases. The peeling method has been recently found to be effective for acne treatment. This study aimed to compare the efficacy of pyruvic acid 50% and salicylic acid 30% peeling in the treatment of mild to moderate acne. Materials and Methods: In a prospective single-blinded clinical trial, 86 patients with acne were randomly assigned into two groups. In both groups, the routine treatment of acne (topical solution of erythromycin 4%, triclorocarban soap, and sunscreen) were used twice a day for 8 weeks. In addition, salicylic acid 30% for the control group and pyruvic acid 50% for the case group were used. In both groups, acne severity index (ASI) was calculated before and at week 2, 4, 6, and 8 of the treatment. Patient satisfaction was assessed at the end of the treatment. Side effects were recorded using a checklist. Results: In both groups, the reduction in the number of comedones, papules, and ASI were statistically significant (P < 0.001) in the course of treatment. However, it was not significant regarding the number of pustules (P = 0.09). None of the number of comedone, papules, pustules, and ASI was statistically different between study groups. Both treatment groups had similar side effects except for scaling in the fifth session, which was significantly lower in salicylic acid – treated patients (P = 0.015). Conclusion: Both pyruvic acid 50% and salicylic acid 30% are effective in the improvement of mild to moderate acne with no significant difference in efficacy and side effects. PMID:27904577

  1. Side-chain to backbone interactions dictate the conformational preferences of a cyclopentane arginine analogue

    PubMed Central

    Revilla-López, Guillem; Torras, Juan; Jiménez, Ana I.; Cativiela, Carlos; Nussinov, Ruth; Alemán, Carlos

    2009-01-01

    The intrinsic conformational preferences of the non-proteinogenic amino acids constructed by incorporating the arginine side chain in the β position of 1-aminocyclopentane-1-carboxylic acid (either in a cis or a trans orientation relative to the amino group) have been investigated using computational methods. These compounds may be considered as constrained analogues of arginine (denoted as c5Arg) in which the orientation of the side chain is fixed by the cyclopentane moiety. Specifically, the N-acetyl-N′-methylamide derivatives of cis and trans-c5Arg have been examined in the gas phase and in solution using B3LYP/6-311+G(d,p) calculations and Molecular Dynamics simulations. Results indicate that the conformational space available to these compounds is highly restricted, their conformational preferences being dictated by the ability of the guanidinium group in the side chain to establish hydrogen-bond interactions with the backbone. A comparison with the behavior previously described for the analogous phenylalanine derivatives is presented. PMID:19236034

  2. Fructose and uric acid in diabetic nephropathy

    PubMed Central

    Bjornstad, Petter; Lanaspa, Miguel A.; Ishimoto, Takuji; Kosugi, Tomoki; Kume, Shinji; Jalal, Diana; Maahs, David M.; Snell-Bergeon, Janet K.; Johnson, Richard J.

    2016-01-01

    Clinical studies have reported associations between serum uric acid levels and the development of diabetic nephropathy, but the underlying mechanisms remain elusive. There is evidence from animal studies that blocking uric acid production protects the kidney from tubulointerstitial injury, which may suggest a causal role for uric acid in the development of diabetic tubular injury. In turn, when fructose, which is endogenously produced in diabetes via the polyol pathway, is metabolised, uric acid is generated from a side-chain reaction driven by ATP depletion and purine nucleotide turnover. For this reason, uric acid derived from endogenous fructose could cause tubulointerstitial injury in diabetes. Accordingly, our research group recently demonstrated that blocking fructose metabolism in a diabetic mouse model mitigated the development of tubulointerstitial injury by lowering tubular uric acid production. In this review we discuss the relationship between uric acid and fructose as a novel mechanism for the development of diabetic tubular injury. PMID:26049401

  3. Managing Chemotherapy Side Effects: Diarrhea

    MedlinePlus

    ... such as Pedialyte ® ••Tea (without caffeine) ••Water ••Applesauce ••Bananas ••Crackers ••Cream of wheat or rice cereal ••Eggs •• ... has a series of 18 Chemotherapy Side Effects Sheets at: www.cancer.gov/chemo-side-effects

  4. The Dark Side of Creativity

    ERIC Educational Resources Information Center

    Cropley, David H., Ed.; Cropley, Arthur J., Ed.; Kaufman, James C., Ed.; Runco, Mark A., Ed.

    2010-01-01

    With few exceptions, scholarship on creativity has focused on its positive aspects while largely ignoring its dark side. This includes not only creativity deliberately aimed at hurting others, such as crime or terrorism, or at gaining unfair advantages, but also the accidental negative side effects of well-intentioned acts. This book brings…

  5. Psychopharmaceuticals: effects and side effects

    PubMed Central

    Kline, Nathan S.

    1959-01-01

    Drugs which affect psychological behaviour are being used in vast amounts nowadays, with, in all too many cases, but scant regard for their exact uses or possible side effects. This article contains a clinical classification of these drugs, followed by an account of their principal side effects and the means of obviating them. PMID:14409889

  6. Side Group Construction in High Polymeric Phosphazenes via Lithiophenoxy Intermediates.

    DTIC Science & Technology

    1980-09-22

    the lithio- C:0 derivatives of aryloxyphosphazene high polymers . These were used as C..3 intermediates for the introduction of phosphine-, organotin ...Department of Chemistry, The Pennsylvania State University University Park, Pennsylvania 16802 ABSTRACT The new lithiophenoxyphosphazene high polymers , [NP...2 ]n or [NP (OC6H4Br-i)x- (OPh) y n at -400C to -60*C. The lithio-derivatives were used as reactive intermediates for the synthesis of polymers of

  7. Side effects of generic competition?

    PubMed

    Hellström, Jörgen; Rudholm, Niklas

    2004-10-01

    This study examined the relationship between generic drug market shares and the number of reported side effects. Yearly time-series data for the number of reported side effects and information on market shares, prices, and quantities from 1972 to 1996 were used in this study. Poisson and negative binomial regression models were used in the statistical analysis. The results show that increased generic market share increases the number of reported side effects for all estimated models. When studying the relationship at the substance level, increasing generic market shares increases the number of side effects for 7 of the 15 substances. Generic substitution laws and measures to increase generic competition may thus have unintended consequences since these results show a positive relationship between generic market shares and reported side effects.

  8. Binding of cationic pentapeptides with modified side chain lengths to negatively charged lipid membranes: Complex interplay of electrostatic and hydrophobic interactions.

    PubMed

    Hoernke, Maria; Schwieger, Christian; Kerth, Andreas; Blume, Alfred

    2012-07-01

    Basic amino acids play a key role in the binding of membrane associated proteins to negatively charged membranes. However, side chains of basic amino acids like lysine do not only provide a positive charge, but also a flexible hydrocarbon spacer that enables hydrophobic interactions. We studied the influence of hydrophobic contributions to the binding by varying the side chain length of pentapeptides with ammonium groups starting with lysine to lysine analogs with shorter side chains, namely omithine (Orn), alpha, gamma-diaminobutyric acid (Dab) and alpha, beta-diaminopropionic acid (Dap). The binding to negatively charged phosphatidylglycerol (PG) membranes was investigated by calorimetry, FT-infrared spectroscopy (FT-IR) and monolayer techniques. The binding was influenced by counteracting and sometimes compensating contributions. The influence of the bound peptides on the lipid phase behavior depends on the length of the peptide side chains. Isothermal titration calorimetry (ITC) experiments showed exothermic and endothermic effects compensating to a different extent as a function of side chain length. The increase in lipid phase transition temperature was more significant for peptides with shorter side chains. FTIR-spectroscopy revealed changes in hydration of the lipid bilayer interface after peptide binding. Using monolayer techniques, the contributions of electrostatic and hydrophobic effects could clearly be observed. Peptides with short side chains induced a pronounced decrease in surface pressure of PG monolayers whereas peptides with additional hydrophobic interactions decreased the surface pressure much less or even lead to an increase, indicating insertion of the hydrophobic part of the side chain into the lipid monolayer.

  9. Surface Propensity of Atmospherically Relevant Amino Acids Studied by XPS.

    PubMed

    Mocellin, Alexandra; Gomes, Anderson Herbert de Abreu; Araújo, Oscar Cardoso; de Brito, Arnaldo Naves; Bjorneholm, Olle

    2017-03-30

    Amino acids constitute an important fraction of the water-soluble organic nitrogen (WSON) compounds in aerosols and are involved in many processes in the atmosphere. In this work, we applied XPS to study aqueous solutions of four amino acids: glycine, alanine, valine and methionine, in their zwitterionic forms. We found that amino acids with hydrophilic side chains and smaller size, GLY and ALA, tend to stay in the bulk of the liquid, while the hydrophobic and bigger amino acids, VAL and MET, are found to concentrate more on the surface. We found experimental evidences that the amino acids have preferential orientation relative to the surface, with the hydrophobic side chain being closer to the surface than the hydrophilic carboxylate group. The observed amino acid surface propensity has implications in atmospheric science as the surface interaction play a central role in cloud droplet formation, and they should be considered in climate models.

  10. Polymethyl methacrylate-co-methacrylic acid coatings with controllable concentration of surface carboxyl groups: A novel approach in fabrication of polymeric platforms for potential bio-diagnostic devices

    NASA Astrophysics Data System (ADS)

    Hosseini, Samira; Ibrahim, Fatimah; Djordjevic, Ivan; Koole, Leo H.

    2014-05-01

    The generally accepted strategy in development of bio-diagnostic devices is to immobilize proteins on polymeric surfaces as a part of detection process for diseases and viruses through antibody/antigen coupling. In that perspective, polymer surface properties such as concentration of functional groups must be closely controlled in order to preserve the protein activity. In order to improve the surface characteristics of transparent polymethacrylate plastics that are used for diagnostic devices, we have developed an effective fabrication procedure of polymethylmetacrylate-co-metacrylic acid (PMMA-co-MAA) coatings with controlled number of surface carboxyl groups. The polymers were processed effectively with the spin-coating technique and the detailed control over surface properties is here by demonstrated through the variation of a single synthesis reaction parameter. The chemical structure of synthesized and processed co-polymers has been investigated with nuclear magnetic resonance spectroscopy (NMR) and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-ToF-MS). The surface morphology of polymer coatings have been analyzed with atomic force microscopy (AFM) and scanning electron microscopy (SEM). We demonstrate that the surface morphology and the concentration of surface -COOH groups (determined with UV-vis surface titration) on the processed PMMA-co-MAA coatings can be precisely controlled by variation of initial molar ratio of reactants in the free-radical polymerization reaction. The wettability of developed polymer surfaces also varies with macromolecular structure.

  11. Side-effects of topical steroids: A long overdue revisit

    PubMed Central

    Coondoo, Arijit; Phiske, Meghana; Verma, Shyam; Lahiri, Koushik

    2014-01-01

    The introduction of topical steroids (TS) of varying potency have rendered the therapy of inflammatory cutaneous disorders more effective and less time-consuming. However the usefulness of these has become a double edged sword with constantly rising instances of abuse and misuse leading to serious local, systemic and psychological side effects. These side effects occur more with TS of higher potency and on particular areas of the body like face and genitalia. The article reviews the side effects of TS with special mention about peadiatric age group, also includes the measures for preventing the side effects. PMID:25396122

  12. DRAMATIC IMPROVEMENTS IN CAUSTIC-SIDE SOLVENT EXTRACTION OF CESIUM THROUGH MORE EFFICIENT STRIPPING

    SciTech Connect

    Delmau, Laetitia Helene; Bazelaire, Eve; Bonnesen, Peter V; Engle, Nancy L; Gorbunova, Maryna; Haverlock, Tamara; Moyer, Bruce A; Ensor, Dale; Meadors, Viola M; Harmon, Ben; Bartsch, Richard A.; Surowiec, Malgorzata A.; Zhou, Hui

    2008-01-01

    Dramatic potential improvements to the chemistry of the Caustic-Side Solvent Extraction (CSSX) process are presented as related to enhancement of cesium stripping. The current process for removing cesium from the alkaline high-level waste (HLW) at the USDOE Savannah River Site employs acidic scrub and strip stages and shows remarkable extraction and selectivity properties for cesium. It was determined that cesium stripping can be greatly improved with caustic or near-neutral stages using sodium hydroxide and boric acid as scrub and strip solutions, respectively. Improvements can also be achieved by appending pH-sensitive functional groups to the calix[4]arene-crown-6 extractant. Addition of a proton-ionizable group to the calixarene frame leads to a dramatic "pH swing" of up to 6 orders of magnitude change in cesium distribution ratio.

  13. The ABRF Edman Sequencing Research Group 2008 Study: Investigation into Homopolymeric Amino Acid N-Terminal Sequence Tags and Their Effects on Automated Edman Degradation

    PubMed Central

    Thoma, R. S.; Smith, J. S.; Sandoval, W.; Leone, J. W.; Hunziker, P.; Hampton, B.; Linse, K. D.; Denslow, N. D.

    2009-01-01

    The Edman Sequence Research Group (ESRG) of the Association of Biomolecular Resource designs and executes interlaboratory studies investigating the use of automated Edman degradation for protein and peptide analysis. In 2008, the ESRG enlisted the help of core sequencing facilities to investigate the effects of a repeating amino acid tag at the N-terminus of a protein. Commonly, to facilitate protein purification, an affinity tag containing a polyhistidine sequence is conjugated to the N-terminus of the protein. After expression, polyhistidine-tagged protein is readily purified via chelation with an immobilized metal affinity resin. The addition of the polyhistidine tag presents unique challenges for the determination of protein identity using Edman degradation chemistry. Participating laboratories were asked to sequence one protein engineered in three configurations: with an N-terminal polyhistidine tag; with an N-terminal polyalanine tag; or with no tag. Study participants were asked to return a data file containing the uncorrected amino acid picomole yields for the first 17 cycles. Initial and repetitive yield (R.Y.) information and the amount of lag were evaluated. Information about instrumentation and sample treatment was also collected as part of the study. For this study, the majority of participating laboratories successfully called the amino acid sequence for 17 cycles for all three test proteins. In general, laboratories found it more difficult to call the sequence containing the polyhistidine tag. Lag was observed earlier and more consistently with the polyhistidine-tagged protein than the polyalanine-tagged protein. Histidine yields were significantly less than the alanine yields in the tag portion of each analysis. The polyhistidine and polyalanine protein-R.Y. calculations were found to be equivalent. These calculations showed that the nontagged portion from each protein was equivalent. The terminal histidines from the tagged portion of the protein

  14. pH-responsive ion transport in polyelectrolyte multilayers of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(4-styrenesulfonic acid-co-maleic acid) (PSS-MA) bearing strong- and weak anionic groups.

    PubMed

    Maza, Eliana; Tuninetti, Jimena S; Politakos, Nikolaos; Knoll, Wolfgang; Moya, Sergio; Azzaroni, Omar

    2015-11-28

    The layer-by-layer construction of interfacial architectures displaying stimuli-responsive control of mass transport is attracting increasing interest in materials science. In this work, we describe the creation of interfacial architectures displaying pH-dependent ionic transport properties which until now have not been observed in polyelectrolyte multilayers. We describe a novel approach to create pH-controlled ion-rectifying systems employing polyelectrolyte multilayers assembled from a copolymer containing both weakly and strongly charged pendant groups, poly(4-styrenesulfonic acid-co-maleic acid) (PSS-MA), alternately deposited with poly(diallyldimethylammonium chloride) (PDADMAC). The conceptual framework is based on the very contrasting and differential interactions of PSS and MA units with PDADMAC. In our setting, sulfonate groups play a structural role by conferring stability to the multilayer due to the strong electrostatic interactions with the polycations, while the weakly interacting MA groups remain "silent" within the film and then act as on-demand pH-responsive units. When these multilayers are combined with a strong cationic capping layer that repels the passage of cationic probes, a pH-gateable rectified transport of anions is observed. Concomitantly, we also observed that these functional properties are significantly affected when multilayers are subjected to extensive pH cycling as a consequence of irreversible morphological changes taking place in the film. We envision that the synergy derived from combining weak and strong interactions within the same multilayer will play a key role in the construction of new interfacial architectures displaying tailorable ion transport properties.

  15. 2. VIEW OF INTERIOR, EAST SIDE (SIDE A) OF BUILDING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW OF INTERIOR, EAST SIDE (SIDE A) OF BUILDING 883. INSTALLATION OF ROLLING MILLS AND MOLTEN SALT BATH EQUIPMENT FOR DEPLETED URANIUM FABRICATION. THE CRANE NEAR THE CEILING WAS USED TO INSTALL THE EQUIPMENT. BOXES ON THE FLOOR CONTAINED EQUIPMENT TO BE INSTALLED. (1/23/57) - Rocky Flats Plant, Uranium Rolling & Forming Operations, Southeast section of plant, southeast quadrant of intersection of Central Avenue & Eighth Street, Golden, Jefferson County, CO

  16. Mercapturic Acids Derived from the Toxicants Acrolein and Crotonaldehyde in the Urine of Cigarette Smokers from Five Ethnic Groups with Differing Risks for Lung Cancer

    PubMed Central

    Park, Sungshim L.; Carmella, Steven G.; Chen, Menglan; Patel, Yesha; Stram, Daniel O.; Haiman, Christopher A.; Le Marchand, Loic; Hecht, Stephen S.

    2015-01-01

    The Multiethnic Cohort epidemiology study has clearly demonstrated that, compared to Whites and for the same number of cigarettes smoked, African Americans and Native Hawaiians have a higher risk for lung cancer whereas Latinos and Japanese Americans have a lower risk. Acrolein and crotonaldehyde are two important constituents of cigarette smoke which have well documented toxic effects and could play a role in lung cancer etiology. Their urinary metabolites 3-hydroxypropylmercapturic acid (3-HPMA) and 3-hydroxy-1-methylpropylmercapturic acid (HMPMA), respectively, are validated biomarkers of acrolein and crotonaldehyde exposure. We quantified levels of 3-HPMA and HMPMA in the urine of more than 2200 smokers from these five ethnic groups, and also carried out a genome wide association study using blood samples from these subjects. After adjusting for age, sex, creatinine, and total nicotine equivalents, geometric mean levels of 3-HPMA and HMPMA were significantly different in the five groups (P<0.0001). Native Hawaiians had the highest and Latinos the lowest geometric mean levels of both 3-HPMA and HMPMA. Levels of 3-HPMA and HMPMA were 3787 and 2759 pmol/ml urine, respectively, in Native Hawaiians and 1720 and 2210 pmol/ml urine in Latinos. These results suggest that acrolein and crotonaldehyde may be involved in lung cancer etiology, and that their divergent levels may partially explain the differing risks of Native Hawaiian and Latino smokers. No strong signals were associated with 3-HPMA in the genome wide association study, suggesting that formation of the glutathione conjugate of acrolein is mainly non-enzymatic, while the top significant association with HMPMA was located on chromosome 12 near the TBX3 gene, but its relationship to HMPMA excretion is not clear. PMID:26053186

  17. Group additivity calculation of the standard molal thermodynamic properties of aqueous amino acids, polypeptides and unfolded proteins as a function of temperature, pressure and ionization state

    NASA Astrophysics Data System (ADS)

    Dick, J. M.; Larowe, D. E.; Helgeson, H. C.

    2005-10-01

    Thermodynamic calculation of the chemical speciation of proteins and the limits of protein metastability affords a quantitative understanding of the biogeochemical constraints on the distribution of proteins within and among different organisms and chemical environments. These calculations depend on accurate determination of the ionization states and standard molal Gibbs free energies of proteins as a function of temperature and pressure, which are not generally available. Hence, to aid predictions of the standard molal thermodynamic properties of ionized proteins as a function of temperature and pressure, calculated values are given below of the standard molal thermodynamic properties at 25°C and 1 bar and the revised Helgeson-Kirkham-Flowers equations of state parameters of the structural groups comprising amino acids, polypeptides and unfolded proteins. Group additivity and correlation algorithms were used to calculate contributions by ionized and neutral sidechain and backbone groups to the standard molal Gibbs free energy (Δ G°), enthalpy (Δ H°), entropy (S°), isobaric heat capacity (C°P), volume (V°) and isothermal compressibility (κ°T) of multiple reference model compounds. Experimental values of C°P, V° and κ°T at high temperature were taken from the recent literature, which ensures an internally consistent revision of the thermodynamic properties and equations of state parameters of the sidechain and backbone groups of proteins, as well as organic groups. As a result, Δ G°, Δ H°, S° C°P, V° and κ°T of unfolded proteins in any ionization state can be calculated up to T~-300°C and P~-5000 bars. In addition, the ionization states of unfolded proteins as a function of not only pH, but also temperature and pressure can be calculated by taking account of the degree of ionization of the sidechain and backbone groups present in the sequence. Calculations of this kind represent a first step in the prediction of chemical affinities of many

  18. Side Effects and Their Management

    MedlinePlus

    ... Menu Care and Treatment Newly Diagnosed Continuum of Care Brain Tumor Treatments Brain Tumor Treatment Locations Treatment Side Effects & their Management Fatigue Memory & Cognitive Changes Depression & Mood Changes Fertility Options Late ...

  19. Coping – Late Side Effects

    Cancer.gov

    Cancer treatment can cause late side effects that may not show up for months or years after treatment. These late effects may include heart and lung problems, bone loss, eye and hearing changes, lymphedema, and other problems

  20. Side Effects of Hormone Therapy

    MedlinePlus

    ... FAQs Why Give to PCF? Featured Blue Jacket Fashion Show Featured Donate Contact Us Menu Close Donate ... Featured Why Give to PCF? Featured Blue Jacket Fashion Show Contact Us Side Effects of Hormone Therapy ...

  1. Novel side branch ostial stent.

    PubMed

    Chen, Shao-Liang; Lv, Shu-Zheng; Kwan, Tak W

    2009-04-01

    Bifurcation lesions are technically challenging and plagued by a high incidence of restenosis, especially at the side branch orifice, which results in a more frequent need for revascularization during the follow-up period. This report discusses two clinical experiences with a novel side branch ostial stent, the BIGUARD stent, designed for the treatment of bifurcation lesions; procedural success with no in-hospital complications was observed in types IVb and Ia lesions.

  2. [Genetic dimorphism in beta-aminoisobutyric acid excretion in patients with atherosclerosis of the coronary artery and in groups at risk for atherosclerosis in the Lithuanian population].

    PubMed

    Spitsyn, V A; Stakishaĭtis, D V; Preĭksha, R A

    1993-11-01

    Frequency of genetic variants of excretion of beta-aminoisobutyric acid (BAIB) in the urea was examined in patients suffering from atherosclerosis of coronary arteries and in risk group for atherosclerosis: children frequently suffering from respiratory viral infection, children with insulin-dependent diabetes mellitus (IDDM) and in adults suffering from IDDM and non-insulin-dependent diabetes mellitus. With the aim to determine whether excretion of BAIB could be related with CMV persistence of with proteolytic activity of blood serum the IgG class antibodies against CMV and level of alpha 1-proteinase inhibitor (alpha 1-PI) in blood serum was tested also. Frequency of high excretors of BAIB was found significantly more often (P < 0.01) in children suffering from virus infection compared to that of population. Frequency distribution of BAIB excretion showed that "high excretors" were found significantly more often in children suffering from atherosclerosis. The difference of BAIB excretion among healthy and diabetics was not defined (P > 0.05). The changes of excretion of BAIB in urea were not related with quantity of alpha 1-PI in blood serum. Investigation reveal a possible relation between high BAIB excretor and latent CMV infection and that this may impact atherogenesis. This leads to a suggestion that children who are often ill with respiratory virus infection may constitute a risk group for coronary atherosclerosis.

  3. Systemic side effects of locally used oxymetazoline

    PubMed Central

    Dokuyucu, Recep; Gokce, Hasan; Sahan, Mustafa; Sefil, Fatih; Tas, Zeynel Abidin; Tutuk, Okan; Ozturk, Atakan; Tumer, Cemil; Cevik, Cengiz

    2015-01-01

    Objectives: The object of the study is to experimentally investigate the possible systemic side effects of Oxymetazoline including its nasal spray which has been in use for a long time both by the physicians and patients. There is no study in the literature to address the damages of oxymetazoline on the end organ. Materials and methods: The study conducted on 2 groups of rat. Group 1 (n = 8): Control; and Group 2 (n = 8): Oxymetazoline. During 4 week, the control group was applied with 2 drops of saline water on each nasal cavity 3 times a day and the other group was applied with 2 drops of oxymetazoline HCl 3 times a day. At the end of experiment, samples from mandible, parotid and tails of the rats were taken in 10% formalin for histopathological investigations. Results: In histopathological experiments, when compared with the control group, the oxymetazoline group showed significant increase in many of the histopathological parameters (ischemic changes: P = 0.0001; congestion: P = 0.0006; arterial thrombosis: P = Ns; PNL accumulations: P = 0.001; necrosis: P = 0.0001; and ulceration: P = 0.014). The results of histopathologic tests on the samples taken from mandible and parotid gland, in comparison with the control group, showed no significant increase (focal inflammation: P = Ns; and lymphocyte aggregation: P = Ns). Conclusion: Due to the damage that the long-term use of nasal spray including oxymetazoline, it may cause injury on the end organ, which we revealed in our histopathological experiments. We believe that it’s essential for the physicians to provide information on the side effects of the medicine to their patients who use for a long term. PMID:25932218

  4. Adsorption of amino acids by fullerenes and fullerene nanowhiskers

    NASA Astrophysics Data System (ADS)

    Hashizume, Hideo; Hirata, Chika; Fujii, Kazuko; Miyazawa, Kun'ichi

    2015-12-01

    We have investigated the adsorption of some amino acids and an oligopeptide by fullerene (C60) and fullerene nanowhiskers (FNWs). C60 and FNWs hardly adsorbed amino acids. Most of the amino acids used have a hydrophobic side chain. Ala and Val, with an alkyl chain, were not adsorbed by the C60 or FNWs. Trp, Phe and Pro, with a cyclic structure, were not adsorbed by them either. The aromatic group of C60 did not interact with the side chain. The carboxyl or amino group, with the frame structure of an amino acid, has a positive or negative charge in solution. It is likely that the C60 and FNWs would not prefer the charged carboxyl or amino group. Tri-Ala was adsorbed slightly by the C60 and FNWs. The carboxyl or amino group is not close to the center of the methyl group of Tri-Ala. One of the methyl groups in Tri-Ala would interact with the aromatic structure of the C60 and FNWs. We compared our results with the theoretical interaction of 20 bio-amino acids with C60. The theoretical simulations showed the bonding distance between C60 and an amino acid and the dissociation energy. The dissociation energy was shown to increase in the order, Val < Phe < Pro < Asp < Ala < Trp < Tyr < Arg < Leu. However, the simulation was not consistent with our experimental results. The adsorption of albumin (a protein) by C60 showed the effect on the side chains of Try and Trp. The structure of albumin was changed a little by C60. In our study Try and Tyr were hardly adsorbed by C60 and FNWs. These amino acids did not show a different adsorption behavior compared with other amino acids. The adsorptive behavior of mono-amino acids might be different from that of polypeptides.

  5. Interaction between two side-by-side inverted flags

    NASA Astrophysics Data System (ADS)

    Huertas-Cerdeira, Cecilia; Fan, Boyu; Barizien, Antoine; Gharib, Morteza

    2015-11-01

    The inverted flag instability occurs when an elastic plate that is free at its leading edge and clamped at its trailing edge is subjected to an axial wind. The oscillating motion that follows has received recent attention. However, previous studies have focused on the dynamics of a single flag even though these are rarely found isolated in natural phenomena, such as the fluttering of leaves in the wind. The interaction between two side-by-side inverted flags has been investigated, analyzing the effects of the distance between flags and the wind speed. Both in-phase and anti-phase coupling have been observed for different ranges of these parameters.

  6. Brushless machine having ferromagnetic side plates and side magnets

    DOEpatents

    Hsu, John S

    2012-10-23

    An apparatus is provided having a cylindrical stator and a rotor that is spaced from a stator to define an annular primary air gap that receives AC flux from the stator. The rotor has a plurality of longitudinal pole portions disposed parallel to the axis of rotation and alternating in polarity around a circumference of the rotor. Each longitudinal pole portion includes portions of permanent magnet (PM) material and at least one of the longitudinal pole portions has a first end and an opposing second end and a side magnet is disposed adjacent the first end and a side pole is disposed adjacent the second end.

  7. Activation of salicylic acid metabolism and signal transduction can enhance resistance to Fusarium wilt in banana (Musa acuminata L. AAA group, cv. Cavendish).

    PubMed

    Wang, Zhuo; Jia, Caihong; Li, Jingyang; Huang, Suzhen; Xu, Biyu; Jin, Zhiqiang

    2015-01-01

    Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. cubens (Foc) is the most serious disease that attacks banana plants. Salicylic acid (SA) can play a key role in plant-microbe interactions. Our study is the first to examine the role of SA in conferring resistance to Foc TR4 in banana (Musa acuminata L. AAA group, cv. Cavendish), which is the greatest commercial importance cultivar in Musa. We used quantitative real-time reverse polymerase chain reaction (qRT-PCR) to analyze the expression profiles of 45 genes related to SA biosynthesis and downstream signaling pathways in a susceptible banana cultivar (cv. Cavendish) and a resistant banana cultivar (cv. Nongke No. 1) inoculated with Foc TR4. The expression of genes involved in SA biosynthesis and downstream signaling pathways was suppressed in a susceptible cultivar and activated in a resistant cultivar. The SA levels in each treatment arm were measured using high-performance liquid chromatography. SA levels were decreased in the susceptible cultivar and increased in the resistant cultivar. Finally, we examined the contribution of exogenous SA to Foc TR4 resistance in susceptible banana plants. The expression of genes involved in SA biosynthesis and signal transduction pathways as well as SA levels were significantly increased. The results suggest that one reason for banana susceptibility to Foc TR4 is that expression of genes involved in SA biosynthesis and SA levels are suppressed and that the induced resistance observed in banana against Foc TR4 might be a case of salicylic acid-dependent systemic acquired resistance.

  8. D-Alanylation of Lipoteichoic Acids Confers Resistance to Cationic Peptides in Group B Streptococcus by Increasing the Cell Wall Density

    PubMed Central

    Saar-Dover, Ron; Bitler, Arkadi; Nezer, Ravit; Shmuel-Galia, Liraz; Firon, Arnaud; Shimoni, Eyal; Trieu-Cuot, Patrick; Shai, Yechiel

    2012-01-01

    Cationic antimicrobial peptides (CAMPs) serve as the first line of defense of the innate immune system against invading microbial pathogens. Gram-positive bacteria can resist CAMPs by modifying their anionic teichoic acids (TAs) with D-alanine, but the exact mechanism of resistance is not fully understood. Here, we utilized various functional and biophysical approaches to investigate the interactions of the human pathogen Group B Streptococcus (GBS) with a series of CAMPs having different properties. The data reveal that: (i) D-alanylation of lipoteichoic acids (LTAs) enhance GBS resistance only to a subset of CAMPs and there is a direct correlation between resistance and CAMPs length and charge density; (ii) resistance due to reduced anionic charge of LTAs is not attributed to decreased amounts of bound peptides to the bacteria; and (iii) D-alanylation most probably alters the conformation of LTAs which results in increasing the cell wall density, as seen by Transmission Electron Microscopy, and reduces the penetration of CAMPs through the cell wall. Furthermore, Atomic Force Microscopy reveals increased surface rigidity of the cell wall of the wild-type GBS strain to more than 20-fold that of the dltA mutant. We propose that D-alanylation of LTAs confers protection against linear CAMPs mainly by decreasing the flexibility and permeability of the cell wall, rather than by reducing the electrostatic interactions of the peptide with the cell surface. Overall, our findings uncover an important protective role of the cell wall against CAMPs and extend our understanding of mechanisms of bacterial resistance. PMID:22969424

  9. [Effect of the B-group vitamin complex on the blood content of saturated and unsaturated fatty acids in patients with ischemic heart disease and hypertension].

    PubMed

    Vodoevich, V P; Buko, V U

    1986-01-01

    Gas-liquid chromatography was used to study the blood content of saturated and unsaturated fatty acids, under the influence of the functionally-associated vitamin-B complex, in 45 patients with coronary heart disease and essential hypertension. The vitamins were given daily in the following doses: thiamine diphosphate 50 mg, riboflavine 40 mg, calcium pantothenate 200 mg, nicotinic acid 200 mg and lipoic acid 50 mg. Favourable shifts leading to positive clinical effects were recorded in the fatty acid metabolism after 10-day taking the vitamin-B complex: the content of unsaturated (linoleic and arachidonic) fatty acids increased while that of saturated (stearic and palmitic) fatty acids decreased.

  10. Anacardic acid: molluscicide in cashew nut shell liquid.

    PubMed

    Sullivan, J T; Richards, C S; Lloyd, H A; Krishna, G

    1982-03-01

    The components of anacardic acid, (a mixture of 6-n-C (15) alkylsalicylic acids whose side chains vary in degrees of unsaturation) have been isolated by high pressure liquid chromatography from a crude extract of cashew nut shell, Anacardium occidentale, and tested for toxicity to fresh water snails, Biomphalaria glabrata. The triene component is the most toxic form (LC (50) 0.35 ppm), the diene and monoene components are less toxic (LC (50) 0.9 and 1.4 ppm), and the saturated component is relatively nontoxic (LC (50) > 5 ppm). Since decarboxylated anacardic acid (cardanol) and salicylic acid do not kill snails at concentrations up to 5 ppm, it appears that both, carboxyl group and unsaturated side chain are absolutely required for molluscicidal activity. The mechanism of toxicity of anacardic acid to snails is unknown.

  11. Side predilections of offending arteries in hemifacial spasm.

    PubMed

    Chung, Moonyoung; Han, Inbo; Chung, Sang-Sup; Huh, Ryoong

    2016-07-01

    The side predilections of various offending arteries in hemifacial spasm (HFS) have not been well studied. The relationship between clinical and radiological features of HFS and offending arteries were investigated in the present study. A retrospective analysis of 370 patients who underwent microvascular decompression for HFS was performed. The patients were divided into four groups based on the offending arteries, namely anterior inferior cerebellar artery (AICA), posterior inferior cerebellar artery (PICA), vertebral artery, and multiple offending arteries. Affected side, age at onset, presence of hypertension, and sigmoid sinus area and dominance were compared between groups. The mean age of patients with a left HFS was significantly greater than that of patients with a right HFS (P=0.009). The AICA affected primarily the right side and PICA and multiple offending arteries the left side (P<0.001). Side of sigmoid sinus dominance was significantly different among groups (P<0.001). The offending arteries in HFS may be related to these differences. AICA was associated with right-sided symptoms, younger age at onset, and presence of left dominant sigmoid sinus, while PICA was associated with left-sided symptoms, older age at onset, and smaller right sigmoid sinus area.

  12. Aminated thermoresponsive microgels prepared from the Hofmann rearrangement of amides without side reactions.

    PubMed

    Wang, Zuohe; Pelton, Robert

    2014-06-17

    Thermoresponsive microgels bearing primary amine groups were prepared by the Hofmann rearrangement of methacrylamide groups present in cross-linked NIPMAM (N-isopropylmethacrylamide) microgels. Most thermoresponsive microgels are based on NIPAM (N-isopropylacrylamide). By substituting NIPMAM for NIPAM, and methacrylamide for acrylamide, side reactions and the generation of carboxyl groups were prevented during the Hofmann reaction. The Hofmann rearrangement is sufficiently slow under our conditions (1 h for a 51% conversion) to permit fine control of the primary amine contents in the microgels. When starting with PNIPMAM microgels containing both methacrylamide and acrylic acid residues, we prepared a series of amphoteric microgels spanning a range of amine contents, all from a common parent microgel. Therefore, every microgel in the series had the same microstructure, cross-link density, and molecular weight.

  13. Quantum Computational Calculations of the Ionization Energies of Acidic and Basic Amino Acids: Aspartate, Glutamate, Arginine, Lysine, and Histidine

    NASA Astrophysics Data System (ADS)

    de Guzman, C. P.; Andrianarijaona, M.; Lee, Y. S.; Andrianarijaona, V.

    An extensive knowledge of the ionization energies of amino acids can provide vital information on protein sequencing, structure, and function. Acidic and basic amino acids are unique because they have three ionizable groups: the C-terminus, the N-terminus, and the side chain. The effects of multiple ionizable groups can be seen in how Aspartate's ionizable side chain heavily influences its preferred conformation (J Phys Chem A. 2011 April 7; 115(13): 2900-2912). Theoretical and experimental data on the ionization energies of many of these molecules is sparse. Considering each atom of the amino acid as a potential departing site for the electron gives insight on how the three ionizable groups affect the ionization process of the molecule and the dynamic coupling between the vibrational modes. In the following study, we optimized the structure of each acidic and basic amino acid then exported the three dimensional coordinates of the amino acids. We used ORCA to calculate single point energies for a region near the optimized coordinates and systematically went through the x, y, and z coordinates of each atom in the neutral and ionized forms of the amino acid. With the calculations, we were able to graph energy potential curves to better understand the quantum dynamic properties of the amino acids. The authors thank Pacific Union College Student Association for providing funds.

  14. Solution of Azelaic Acid (20%), Resorcinol (10%) and Phytic Acid (6%) Versus Glycolic Acid (50%) Peeling Agent in the Treatment of Female Patients with Facial Melasma

    PubMed Central

    Faghihi, Gita; Taheri, Azam; Shahmoradi, Zabihollah; Nilforoushzadeh, Mohammad Ali

    2017-01-01

    Background: Melasma, a common acquired disorder of hyperpigmentation, especially in women, is often resistant to therapy. This study was aimed to evaluate the efficacy and safety of azelaic acid, resorcinol and phytic acid solution in chemical peeling of melasma in comparison to 50% glycolic acid. Materials and Methods: This clinical trial was performed, on 42 female patients with bilateral melasma. Severity of melasma was assessed by melasma area and severity index (MASI). Combination of (20% azelaic acid + 10% resorcinol + 6% phytic acid) was used as a new peeling agent on the right side of the face and 50% glycolic acid on the left side every 2 weeks for 6 times. Follow-up was carried out for 3 months after the last session. Any decrease in MASI score and unwanted complications following peeling were evaluated and compared during the trial. Results: Patients showed marked improvement as calculated with MASI score before and after treatment in both sides of the face. The efficacy of combination formula (azelaic acid, resorcinol and phytic acid) was similar to glycolic acid, but with fewer complications. There was no statistically difference in improvement between two groups (P > 0.05). However, the patient's discomfort following procedures was significantly lower with azelaic acid, resorcinol and phytic compared with the glycolic acid peels (P < 0.05) and there was the same duration in the beginning of the therapeutic response in both groups. Conclusion: Results showed that triple-combination was found to be an effective and safe peeling agent in the treatment of melasma and it was as effective as 50% glycolic acid peel. PMID:28299301

  15. Novel Fluorinated Polymers Containing Short Perfluorobutyl Side Chains and Their Super Wetting Performance on Diverse Substrates.

    PubMed

    Jiang, Jingxian; Zhang, Guangfa; Wang, Qiongyan; Zhang, Qinghua; Zhan, Xiaoli; Chen, Fengqiu

    2016-04-27

    Because the emission of perfluorooctanoic acid (PFOA) was completely prohibited in 2015, the widely used poly- and perfluoroalkyl substances with long perfluoroalkyl groups must be substituted by environmentally friendly alternatives. In this study, one kind of potential alternative (i.e., fluorinated polymers with short perfluorobutyl side chains) has been synthesized from the prepared monomers {i.e., (perfluorobutyl)ethyl acrylate (C4A), (perfluorobutyl)ethyl methacrylate (C4MA), 2-[[[[2-(perfluorobutyl)]sulfonyl]methyl]amino]ethyl acrylate (C4SA), and methacrylate (C4SMA)}, and the microstructure, super wetting performance, and applications of the synthesized fluorinated polymers were systematically investigated. The thermal and crystallization behaviors of the fluoropolymer films were characterized by differential scanning calorimetry and wide-angle X-ray diffraction analysis, respectively. Dynamic water-repellent models were constructed. The stable low surface energy and dynamic water- and oil-repellent properties of these synthesized fluorinated polymers with short perfluorobutyl side chains were attributed to the synergetic effect of amorphous fluorinated side chains in perfluoroalkyl acrylate and crystalline hydrocarbon pendant groups in stearyl acrylate. Outstanding water- and oil-repellent properties of fabrics and any other substrates could be achieved by a facile dip-coating treatment using a fluorinated copolymer dispersion. As a result, we believe that our prepared fluorinated copolymers are potential candidates to replace the fluoroalkylated polymers with long perfluorinated chains in nonstick and self-cleaning applications in our daily life.

  16. Predictions of Daily Milk and Fat Yields, Major Groups of Fatty Acids, and C18:1 cis-9 from Single Milking Data without a Milking Interval.

    PubMed

    Arnould, Valérie M R; Reding, Romain; Bormann, Jeanne; Gengler, Nicolas; Soyeurt, Hélène

    2015-07-31

    Reducing the frequency of milk recording would help reduce the costs of official milk recording. However, this approach could also negatively affect the accuracy of predicting daily yields. This problem has been investigated in numerous studies. In addition, published equations take into account milking intervals (MI), and these are often not available and/or are unreliable in practice. The first objective of this study was to propose models in which the MI was replaced by a combination of data easily recorded by dairy farmers. The second objective was to further investigate the fatty acids (FA) present in milk. Equations to predict daily yield from AM or PM data were based on a calibration database containing 79,971 records related to 51 traits [milk yield (expected AM, expected PM, and expected daily); fat content (expected AM, expected PM, and expected daily); fat yield (expected AM, expected PM, and expected daily; g/day); levels of seven different FAs or FA groups (expected AM, expected PM, and expected daily; g/dL milk), and the corresponding FA yields for these seven FA types/groups (expected AM, expected PM, and expected daily; g/day)]. These equations were validated using two distinct external datasets. The results obtained from the proposed models were compared to previously published results for models which included a MI effect. The corresponding correlation values ranged from 96.4% to 97.6% when the daily yields were estimated from the AM milkings and ranged from 96.9% to 98.3% when the daily yields were estimated from the PM milkings. The simplicity of these proposed models should facilitate their use by breeding and milk recording organizations.

  17. Functional Group Analysis.

    ERIC Educational Resources Information Center

    Smith, Walter T., Jr.; Patterson, John M.

    1984-01-01

    Literature on analytical methods related to the functional groups of 17 chemical compounds is reviewed. These compounds include acids, acid azides, alcohols, aldehydes, ketones, amino acids, aromatic hydrocarbons, carbodiimides, carbohydrates, ethers, nitro compounds, nitrosamines, organometallic compounds, peroxides, phenols, silicon compounds,…

  18. Radiolabeling of Poly(lactic-co-glycolic acid) (PLGA) Nanoparticles with Biotinylated F-18 Prosthetic Groups and Imaging of Their Delivery to the Brain with Positron Emission Tomography

    PubMed Central

    2015-01-01

    The avidin–biotin interaction permits rapid and nearly irreversible noncovalent linkage between biotinylated molecules and avidin-modified substrates. We designed a biotinylated radioligand intended for use in the detection of avidin-modified polymer nanoparticles in tissue with positron emission tomography (PET). Using an F-18 labeled prosthetic group, [18F]4-fluorobenzylamine, and a commercially available biotin derivate, NHS-PEG4-biotin, [18F]-fluorobenzylamide-poly(ethylene glycol)4-biotin ([18F]NPB4) was prepared with high purity and specific activity. The attachment of the [18F]NPB4 radioligand to avidin-modified poly(lactic-co-glycolic acid) (PLGA) nanoparticles was tested by using PET imaging to measure the kinetics of convection-enhanced delivery (CED) of nanoparticles of varying size to the rat brain. PET imaging enabled the direct observation of nanoparticle delivery by measurement of the spatial volume of distribution of radiolabeled nanoparticles as a function of time, both during and after the infusion. This work thus validates new methods for radiolabeling PEG-biotin derivatives and also provides insight into the fate of nanoparticles that have been infused directly into the brain. PMID:25322194

  19. CO2-Free Power Generation on an Iron Group Nanoalloy Catalyst via Selective Oxidation of Ethylene Glycol to Oxalic Acid in Alkaline Media

    NASA Astrophysics Data System (ADS)

    Matsumoto, Takeshi; Sadakiyo, Masaaki; Ooi, Mei Lee; Kitano, Sho; Yamamoto, Tomokazu; Matsumura, Syo; Kato, Kenichi; Takeguchi, Tatsuya; Yamauchi, Miho

    2014-07-01

    An Fe group ternary nanoalloy (NA) catalyst enabled selective electrocatalysis towards CO2-free power generation from highly deliverable ethylene glycol (EG). A solid-solution-type FeCoNi NA catalyst supported on carbon was prepared by a two-step reduction method. High-resolution electron microscopy techniques identified atomic-level mixing of constituent elements in the nanoalloy. We examined the distribution of oxidised species, including CO2, produced on the FeCoNi nanoalloy catalyst in the EG electrooxidation under alkaline conditions. The FeCoNi nanoalloy catalyst exhibited the highest selectivities toward the formation of C2 products and to oxalic acid, i.e., 99 and 60%, respectively, at 0.4 V vs. the reversible hydrogen electrode (RHE), without CO2 generation. We successfully generated power by a direct EG alkaline fuel cell employing the FeCoNi nanoalloy catalyst and a solid-oxide electrolyte with oxygen reduction ability, i.e., a completely precious-metal-free system.

  20. CO2-Free Power Generation on an Iron Group Nanoalloy Catalyst via Selective Oxidation of Ethylene Glycol to Oxalic Acid in Alkaline Media

    PubMed Central

    Matsumoto, Takeshi; Sadakiyo, Masaaki; Ooi, Mei Lee; Kitano, Sho; Yamamoto, Tomokazu; Matsumura, Syo; Kato, Kenichi; Takeguchi, Tatsuya; Yamauchi, Miho

    2014-01-01

    An Fe group ternary nanoalloy (NA) catalyst enabled selective electrocatalysis towards CO2-free power generation from highly deliverable ethylene glycol (EG). A solid-solution-type FeCoNi NA catalyst supported on carbon was prepared by a two-step reduction method. High-resolution electron microscopy techniques identified atomic-level mixing of constituent elements in the nanoalloy. We examined the distribution of oxidised species, including CO2, produced on the FeCoNi nanoalloy catalyst in the EG electrooxidation under alkaline conditions. The FeCoNi nanoalloy catalyst exhibited the highest selectivities toward the formation of C2 products and to oxalic acid, i.e., 99 and 60%, respectively, at 0.4 V vs. the reversible hydrogen electrode (RHE), without CO2 generation. We successfully generated power by a direct EG alkaline fuel cell employing the FeCoNi nanoalloy catalyst and a solid-oxide electrolyte with oxygen reduction ability, i.e., a completely precious-metal-free system. PMID:25004118

  1. Histidine and Aspartic Acid Residues Important for Immunoglobulin G Endopeptidase Activity of the Group A Streptococcus Opsonophagocytosis-Inhibiting Mac Protein

    PubMed Central

    Lei, Benfang; Liu, Mengyao; Meyers, Elishia G.; Manning, Heather M.; Nagiec, Michael J.; Musser, James M.

    2003-01-01

    The secreted Mac protein made by serotype M1 group A Streptococcus (GAS) (designated Mac5005) inhibits opsonophagocytosis and killing of GAS by human polymorphonuclear neutrophils. This protein also has cysteine endopeptidase activity against human immunoglobulin G (IgG). Site-directed mutagenesis was used to identify histidine and aspartic acid residues important for Mac IgG endopeptidase activity. Replacement of His262 with Ala abolished Mac5005 IgG endopeptidase activity. Asp284Ala and Asp286Ala mutant proteins had compromised enzymatic activity, whereas 21 other Asp-to-Ala mutant proteins cleaved human IgG at the apparent wild-type level. The results suggest that His262 is an active-site residue and that Asp284 and Asp286 are important for the enzymatic activity or structure of Mac protein. These Mac mutants provide new information about structure-activity relationships in this protein and will assist study of the mechanism of inhibition of opsonophagocytosis and killing of GAS by Mac. PMID:12704162

  2. Oxidative processes in the Australian marine sponge Plakinastrella clathrata: isolation of plakortolides with oxidatively modified side chains.

    PubMed

    Yong, Ken W L; Lambert, Lynette K; Hayes, Patricia Y; De Voss, James J; Garson, Mary J

    2012-03-23

    Sixteen new cyclic peroxides (1-16) with a plakortolide skeleton and the methyl ester derivative of a didehydroplakinic acid (17) were isolated from the Australian sponge Plakinastrella clathrata Kirkpatrick, 1900. Structural elucidation and configurational assignments were based on spectroscopic analysis and comparison with data for previously isolated plakortolides and revealed both phenyl- and methyl-terminating side chains attached to the plakortolide core. Plakortoperoxides A-D (5-8) each contained a second 1,2-dioxine ring; a cis configuration for the side chain endoperoxide ring was determined by a low-temperature NMR study and by comparison of chemical shift values with those of reported compounds. An enantioselective HPLC study compared natural plakortoperoxide A with a synthetic sample prepared by cyclization of plakortolide P with singlet oxygen and revealed that the natural sample was a mixture of cis diastereomers at C-15/C18. Four other cyclic peroxides (9-12) possessed a C(9)-truncated side chain terminating in a formyl or carboxylic acid functionality, suggesting that these metabolites may have been formed by oxidative cleavage of the Δ(9,10) bond of diene-functionalized plakortolides. A final group of four metabolites (13-16) with hydroxy or the rare hydroperoxy functionality unexpectedly revealed a C(8) side chain, while the ester (17) represents further structural variation within the growing family of cyclic peroxy sponge metabolites.

  3. Side-on bound diazene and hydrazine complexes of ruthenium.

    PubMed

    Field, Leslie D; Li, Hsiu L; Dalgarno, Scott J

    2010-07-05

    The reaction of cis-[RuCl(2)(PP)(2)] (PP = depe, dmpe) with hydrazine afforded end-on bound ruthenium(II) hydrazine complexes. Treatment of the hydrazine complexes with strong base afforded the side-on bound ruthenium(0) diazene complexes cis-[Ru(eta(2)-NH=NH)(PP)(2)]. Treatment of cis-[Ru(eta(2)-NH=NH)(depe)(2)] with weak acid under chloride-free conditions afforded the side-on bound hydrazine complex cis-[Ru(eta(2)-N(2)H(4))(depe)(2)](2+). These are the first reported side-on bound diazene and hydrazine complexes of ruthenium, and they have been characterized by NMR spectroscopy ((1)H, (31)P, (15)N) and by X-ray crystallography. The interconversion between the ruthenium diazene and the ruthenium hydrazine by acid-base treatment was reversible.

  4. Radiation Therapy: Preventing and Managing Side Effects

    MedlinePlus

    ... who share your problems and concerns. Will side effects limit my activity? Side effects might limit your ... that might irritate the area being treated. Side effects can vary. Your cancer care team can tell ...

  5. Side hole drilling in boreholes

    NASA Technical Reports Server (NTRS)

    Collins, Jr., Earl R. (Inventor)

    1980-01-01

    Apparatus for use in a borehole or other restricted space to bore a side hole into the strata surrounding the borehole, including a flexible shaft with a drill at its end, and two trains of sheathing members that can be progressively locked together into a rigid structure around the flexible shaft as it is directed sidewardly into the strata.

  6. The Lighter Side of Teaching.

    ERIC Educational Resources Information Center

    Bacall, Aaron

    This book presents a collection of cartoons that focus on the lighter side of teaching. In a tongue-in-cheek introduction, the book asserts that one achievable goal which should have been included in the 1994 Educate America Act is that all teachers will start each school day by reading one funny cartoon and having a good chuckle before they go to…

  7. The Human Side of Libraries.

    ERIC Educational Resources Information Center

    Surace, Cecily J.

    This paper discusses current trends in personnel management, with emphasis on performance standards and employee evaluation. Advances in personnel management from the scientific management theory to the application of the "human side of enterprise" approach should be reflected in how library managers review personnel and operate their libraries.…

  8. Side chain effects in reactions of the potassium-tyrosine charge transfer complex

    NASA Astrophysics Data System (ADS)

    da Silva, F. Ferreira; Meneses, G.; Ingólfsson, O.; Limão-Vieira, P.

    2016-10-01

    Fragmentation of transient negative ions of tyrosine formed through electron transfer in collisions with neutral potassium atoms is presented in the collision energy range from 30 to 75 eV. At low collision energies the dominating side chain channel observed corresponds to the cleavage of the bond from the para-position of the phenyl ring to the β-C of the remaining moiety, but cleavage of the Cαsbnd Cβ bond is also observed. Further fragments are formed through cleavage of the Cα bond to the carbonyl group, through decomposition of the carboxyl group or through significant decomposition of the backbone. The dehydrogenated molecular anion is also observed with appreciable intensity. These results are discussed in the context of earlier studies on dissociative electron attachment to tyrosine and other amino acids, as well as within the role of the side chain in electron induced decomposition of this aromatic amino acid. Stabilization of the temporary molecular anion in the transient collision complex is discussed and we argue that this may have significant influence on the branching ratios observed.

  9. Effect of Axonal Trauma on Nerve Regeneration in Side-to-side Neurorrhaphy: An Experimental Study

    PubMed Central

    Göransson, Harry; Taskinen, Hanna-Stiina; Paavilainen, Pasi; Vahlberg, Tero; Röyttä, Matias

    2016-01-01

    Background: Side-to-side (STS) neurorrhaphy can be performed distally to ensure timely end-organ innervation. It leaves the distal end of the injured nerve intact for further reconstruction. Despite encouraging clinical results, only few experimental studies have been published to enhance the regeneration results of the procedure. We examined the influence of different size epineural windows and degree of axonal injury of STS repair on nerve regeneration and donor nerve morbidity. Methods: Three clinically relevant repair techniques of the transected common peroneal nerve (CPN) were compared. Group A: 10-mm long epineural STS windows; group B: 2-mm long windows and partial axotomy to the donor tibial nerve; and group C: 2-mm long windows with axotomies to both nerves. Regeneration was followed by the walk track analysis, nerve morphometry, histology, and wet muscle mass calculations. Results: The results of the walk track analysis were significantly better in groups B and C compared with group A. The nerve fiber count, total fiber area, fiber density, and percentage of the fiber area values of CPN of the group C were significantly higher when compared with group A. The wet mass ratio of the CPN-innervated anterior tibial muscle was significantly higher in group C compared with group A. The wet mass ratio of the tibial nerve–innervated gastrocnemial muscle was higher in group A compared with the other groups. Conclusions: All three variations of the STS repair technique showed nerve regeneration. Deliberate donor nerve axotomy enhanced nerve regeneration. A larger epineural window did not compensate the effect of axonal trauma on nerve regeneration. PMID:28293524

  10. Exanthema medicamentosum as a side effect of promazine.

    PubMed

    Lasić, Davor; Cvitanović, Marija Zuljan; Uglešić, Boran; Višić, Vitomir; Hlevnjak, Ivana

    2011-06-01

    Dermatological side effects of psychopharmacological drugs are fortunately not so often. They are mostly presented in the group of mood stabilizers and antiepileptic drugs, particularly the carbamazepine and lamotrigine, and can be manifested through the Stevens Johnson syndrome, Toxic Epidermal Necrolysis (TEN)/Lyell's syndrome with about 30% lethality. According to the literature the group of phenothiazines is the category of drugs with rare appearances of skin reactions. Promazine, aliphatic phenothiazines antipsychotic, including less frequent side effects in the leaflet states increased skin sensitivity to sun, skin rash-associated with contact dermatitis, allergic reactions, cholestatic icterus. The only reported dermatological side effect of promazine is its metabolites deposition in the cornea. Analyzing the e-data basis we have not found references connecting the Exanthema medicamentosum as a side effect of promazine. A forty-two years old female patient was admitted to the Dermatological Clinic because of suspected exanthema, undoubtedly caused by promazine as a medication for Sy. Borderline.

  11. Air Quality Side Event Proposal November 2016 GEO XIII ...

    EPA Pesticide Factsheets

    The Group on Earth Observations (GEO), which EPA has participated in since 2003, has put out a call for Side Events for its thirteenth annual international Plenary Meeting which is in St. Petersburg, Russia this year during November, 2016. EPA has put on Side Events on Air Quality and Health observational systems at eight of the previous Plenaries. This document is a Side Event proposal regarding air quality, health and next generation monitoring and observations techniques. It is submitted to the GEO Secretariat for consideration. If accepted, there will likely be presentations by EPA and NASA, other GEO Member Countries and UNEP and other GEO Participating Organizations at the Side Event. It is an opportunity to share scientific and technological advances in this area and build partnerships and collaboration. The Group on Earth Observations (GEO), which EPA has participated in since 2003, has put out a call for Side Events for its thirteenth annual international Plenary Meeting which is in St. Petersburg, Russia this year during November, 2016. EPA has put on Side Events on Air Quality and Health observational systems at eight of the previous Plenaries. This document is a Side Event proposal regarding air quality, health and next generation monitoring and observations techniques.  It is submitted to the GEO Secretariat for consideration. If accepted, there will likely be presentations by EPA and NASA, other GEO Member Countries and UNEP and other GEO P

  12. Argentivorous molecules with two kinds of aromatic side-arms: intramolecular competition between side-arms.

    PubMed

    Habata, Yoichi; Oyama, Yosuke; Ikeda, Mari; Kuwahara, Shunsuke

    2013-06-21

    Three tetra-armed cyclens with two kinds of side-arms, 3',5'-difluorobenzyl/4'-methylbenzyl, 3',5'-difluorobenzyl/1'-naphthylmethyl, and 3',5'-difluorobenzyl/9'-anthrylmethyl groups, were prepared by reductive amination of 1,7-bis(3',5'-difluorobenzyl)-1,4,7,10-tetraazacyclododecane and the corresponding aromatic aldehydes in the presence of NaBH(OAc)3. The X-ray structures of the Ag(+) complexes and Ag(+)-ion-induced (1)H NMR spectral changes suggest that (i) the chemical shift changes of the protons at the 2'- and 6'-positions in the 3',5'-difluorobenzyl/4'-methylbenzyl side-arms are dependent on the electron density on the adjacent substituted benzenes, and (ii) in the tetra-armed cyclens with 3',5'-difluorobenzyl/1'-naphthylmethyl and 3',5'-difluorobenzyl/9'-anthrylmethyl groups as side-arms, electron-rich aromatic rings preferentially cover the Ag(+) ions incorporated into the ligand cavities, and 3',5'-difluorobenzyl groups do not participate in the Ag(+) interactions. The log K values were estimated using Ag(+)-ion-induced UV-vis spectral changes.

  13. Plasmidic Expression of nemA and yafC* Increased Resistance of Ethanologenic Escherichia coli LY180 to Nonvolatile Side Products from Dilute Acid Treatment of Sugarcane Bagasse and Artificial Hydrolysate.

    PubMed

    Shi, Aiqin; Zheng, Huabao; Yomano, Lorraine P; York, Sean W; Shanmugam, Keelnatham T; Ingram, Lonnie O

    2016-01-29

    Hydrolysate-resistant Escherichia coli SL100 was previously isolated from ethanologenic LY180 after sequential transfers in AM1 medium containing a dilute acid hydrolysate of sugarcane bagasse and was used as a source of resistance genes. Many genes that affect tolerance to furfural, the most abundant inhibitor, have been described previously. To identify genes associated with inhibitors other than furfural, plasmid clones were selected in an artificial hydrolysate that had been treated with a vacuum to remove furfural. Two new resistance genes were discovered from Sau3A1 libraries of SL100 genomic DNA: nemA (N-ethylmaleimide reductase) and a putative regulatory gene containing a mutation in the coding region, yafC*. The presence of these mutations in SL100 was confirmed by sequencing. A single mutation was found in the upstream regulatory region of nemR (nemRA operon) in SL100. This mutation increased nemA activity 20-fold over that of the parent organism (LY180) in AM1 medium without hydrolysate and increased nemA mRNA levels >200-fold. Addition of hydrolysates induced nemA expression (mRNA and activity), in agreement with transcriptional control. NemA activity was stable in cell extracts (9 h, 37°C), eliminating a role for proteinase in regulation. LY180 with a plasmid expressing nemA or yafC* was more resistant to a vacuum-treated sugarcane bagasse hydrolysate and to a vacuum-treated artificial hydrolysate than LY180 with an empty-vector control. Neither gene affected furfural tolerance. The vacuum-treated hydrolysates inhibited the reduction of N-ethylmaleimide by NemA while also serving as substrates. Expression of the nemA or yafC* plasmid in LY180 doubled the rate of ethanol production from the vacuum-treated sugarcane bagasse hydrolysate.

  14. Dipeptides as effective prodrugs of the unnatural amino acid (+)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (LY354740), a selective group II metabotropic glutamate receptor agonist.

    PubMed

    Bueno, Ana Belén; Collado, Iván; de Dios, Alfonso; Domínguez, Carmen; Martín, José Alfredo; Martín, Luisa M; Martínez-Grau, María Angeles; Montero, Carlos; Pedregal, Concepción; Catlow, John; Coffey, D Scott; Clay, Michael P; Dantzig, Anne H; Lindstrom, Terry; Monn, James A; Jiang, Haiyan; Schoepp, Darryle D; Stratford, Robert E; Tabas, Linda B; Tizzano, Joseph P; Wright, Rebecca A; Herin, Marc F

    2005-08-11

    (+)-2-Aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (1), also known as LY354740, is a highly potent and selective agonist for group II metabotropic glutamate receptors (mGlu receptors 2 and 3) tested in clinical trials. It has been shown to block anxiety in the fear-potentiated startle model. Its relatively low bioavailability in different animal species drove the need for an effective prodrug form that would produce a therapeutic response at lower doses for the treatment of anxiety disorders. We have investigated the increase of intestinal absorption of this compound by targeting the human peptide transporter hPepT1 for active transport of di- and tripeptides derived from 1. We have found that oral administration of an N dipeptide derivative of 1 (12a) in rats shows up to an 8-fold increase in drug absorption and a 300-fold increase in potency in the fear-potentiated startle model in rats when compared with the parent drug 1.

  15. Electrospray ionization tandem mass spectrometric study of salt cluster ions: part 2--salts of polyatomic acid groups and of multivalent metals.

    PubMed

    Hao, C; March, R E

    2001-05-01

    these four salts of polyatomic acid groups indicate that changes in pH occur in both directions during the electrospray process principally by solvent evaporation; the pH value of the acidic solution became lower and that of the basic solution higher.

  16. Predictions of Daily Milk and Fat Yields, Major Groups of Fatty Acids, and C18:1 cis-9 from Single Milking Data without a Milking Interval

    PubMed Central

    Arnould, Valérie M. R.; Reding, Romain; Bormann, Jeanne; Gengler, Nicolas; Soyeurt, Hélène

    2015-01-01

    Simple Summary Reducing the frequency of milk recording decreases the costs of official milk recording. However, this approach can negatively affect the accuracy of predicting daily yields. Equations to predict daily yield from morning or evening data were developed in this study for fatty milk components from traits recorded easily by milk recording organizations. The correlation values ranged from 96.4% to 97.6% (96.9% to 98.3%) when the daily yields were estimated from the morning (evening) milkings. The simplicity of the proposed models which do not include the milking interval should facilitate their use by breeding and milk recording organizations. Abstract Reducing the frequency of milk recording would help reduce the costs of official milk recording. However, this approach could also negatively affect the accuracy of predicting daily yields. This problem has been investigated in numerous studies. In addition, published equations take into account milking intervals (MI), and these are often not available and/or are unreliable in practice. The first objective of this study was to propose models in which the MI was replaced by a combination of data easily recorded by dairy farmers. The second objective was to further investigate the fatty acids (FA) present in milk. Equations to predict daily yield from AM or PM data were based on a calibration database containing 79,971 records related to 51 traits [milk yield (expected AM, expected PM, and expected daily); fat content (expected AM, expected PM, and expected daily); fat yield (expected AM, expected PM, and expected daily; g/day); levels of seven different FAs or FA groups (expected AM, expected PM, and expected daily; g/dL milk), and the corresponding FA yields for these seven FA types/groups (expected AM, expected PM, and expected daily; g/day)]. These equations were validated using two distinct external datasets. The results obtained from the proposed models were compared to previously published results for

  17. Assessment of a new lateral flow immunochromatographic (LFIC) assay for the okadaic acid group of toxins using naturally contaminated bivalve shellfish from the Portuguese coast.

    PubMed

    Vale, P; Gomes, S S; Lameiras, J; Rodrigues, S M; Botelho, M J; Laycock, M V

    2009-02-01

    A new rapid assay for the okadaic acid group of toxins, based on lateral flow immunochromatographic (LFIC) test strips developed by Jellett Rapid Testing Ltd., was assessed on naturally contaminated bivalves from the Portuguese coast. One prototype was evaluated using samples harvested during 2005, extracted with 80% methanol, followed by dilution with the running buffer of a methanolic extract after alkaline hydrolysis for esters. The second prototype was assessed using samples harvested during 2006, extracted with 100% methanol and, after alkaline hydrolysis, the methanol was evaporated by a nitrogen stream followed by re-suspension with the running buffer. The first prototype failed to detect 20% of samples that were positive by LC-MS in the range 160-480 microg kg(-1), and were classified as negative or trace level by LFIC. The presence of methanol in the extracts made correct detection of toxins more difficult. The second prototype classified as positive all samples above 160 microg kg(-1), as confirmed by LC-MS. However, in the second prototype, matrix effects were a major drawback and led to 45% false positives, particularly for mussels, due to compounds in shellfish extracts interfering with the antibodies and reducing the test line intensity. Extraction with a higher percentage of methanol was thought responsible for these matrix effects. Regarding sample migration, both prototypes needed one hour before reading. In an attempt to speed-up sample preparation, a direct digestion of bivalve tissues with sodium hydroxide was evaluated. Low recoveries for esters were found by LC-MS with this hydrolysis technique compared to conventional hydrolysis of methanolic extracts. While prototype A was not sensitive enough, prototype B had too many false positives to be of use to the shellfish industry or in a monitoring program.

  18. (N-pyrrolyl)B(C6F5)2--a new organometallic Lewis acid for the generation of group 4 metallocene cation complexes.

    PubMed

    Kehr, G; Fröhlich, R; Wibbeling, B; Erker, G

    2000-01-01

    Treatment of the (C6F5)2BF x OEt2 (3) complex with N-pyrrolyl lithium gives bis(pentafluorophenyl)(N-pyrrolyl)borane (2), a strong organometallic Lewis acid, which was characterized by X-ray diffraction (B-N bond length: 1.401(5) A). It exhibits a columnar superstructure in the crystal and contains pi-stacks of pyrrolyl units. Compound 2 readily abstracts alkyl anions from a variety of alkyl Group 4 metallocene-type complexes and leads to the clean formation of the respective metallocene ions or ion pairs. For example, the treatment of Cp3ZrCH3 (9) with 2 transfers a methyl anion to yield the ion pair [Cp3Zr]+[(C4H4N)B(CH3)(C6F5)2]- (12). The X-ray crystal structure analysis of 12 shows a close contact between zirconium and the pyrrolyl-beta-carbon (2.641(2) A). The borane 2 adds to (butadiene)zirconocene (13) to yield the betaine system [Cp2Zr]+[(C4H6)B- (NC4H4)(C6F)2]- (15). Complex 15 contains a distorted eta3-allyl moiety inside the metallacyclic framework and it features an internal Zr+...(pyrrolyl)B- ion pair interaction with a Zr...pyrrolyl-alphacarbon separation of 2.723(3) A (determined by X-ray diffraction). From the dynamic NMR spectra of 15 the bond strength of the internal ion pair interaction was estimated to be deltaGdiss (223 K) approximately = to15 kcalmol(-1). Treatment of dimethylzirconocene (16) with 2 yields the metallocene borate salt [Cp2ZrCH3]+[(C4H4N)B(CH3)(C6F5)2]- (17), which is an active catalyst for the polymerization of ethene.

  19. The compromise of macrophage functions by hyperoxia is attenuated by ethacrynic acid via inhibition of NF-κB-mediated release of high-mobility group box-1.

    PubMed

    Wang, Mao; Gorasiya, Samir; Antoine, Daniel J; Sitapara, Ravikumar A; Wu, Wenjun; Sharma, Lokesh; Yang, Huan; Ashby, Charles R; Vasudevan, Divya; Zur, Michelle; Thomas, Douglas D; Mantell, Lin L

    2015-02-01

    The prolonged exposure to hyperoxia can compromise macrophage functions and contribute to the development of ventilator-associated pneumonia. High levels of extracellular high-mobility group box-1 (HMGB1) in the airways of mice exposed to hyperoxia can directly cause macrophage dysfunction. Hence, inhibition of the release of nuclear HMGB1 into the extracellular milieu may help to maintain macrophage functions under hyperoxic conditions. The present study investigates whether ethacrynic acid (EA) affects hyperoxia-induced HMGB1 release from macrophages and improves their functions. Macrophage-like RAW 264.7 cells and bone marrow-derived macrophages were exposed to different concentrations of EA for 24 hours in the presence of 95% O2. EA significantly decreased the accumulation of extracellular HMGB1 in cultured media. Importantly, the phagocytic activity and migration capability of macrophages were significantly enhanced in EA-treated cells. Interestingly, hyperoxia-induced NF-κB activation was also inhibited in these cells. To determine whether NF-κB plays a role in hyperoxia-induced HMGB1 release, BAY 11-7082, an inhibitor of NF-κB activation, was used. Similar to EA, BAY 11-7082 significantly inhibited the accumulation of extracellular HMGB1 and improved hyperoxia-compromised macrophage migration and phagocytic activity. Furthermore, 24-hour hyperoxic exposure of macrophages caused hyperacetylation of HMGB1 and its subsequent cytoplasmic translocation and release, which were inhibited by EA and BAY 11-7082. Together, these results suggest that EA enhances hyperoxia-compromised macrophage functions by inhibiting HMGB1 hyperacetylation and its release from macrophages, possibly through attenuation of the NF-κB activation. Therefore, the activation of NF-κB could be one of the underlying mechanisms that mediate hyperoxia-compromised macrophage functions.

  20. Metal cation dependence of interactions with amino acids: bond dissociation energies of Rb(+) and Cs(+) to the acidic amino acids and their amide derivatives.

    PubMed

    Armentrout, P B; Yang, Bo; Rodgers, M T

    2014-04-24

    Metal cation-amino acid interactions are key components controlling the secondary structure and biological function of proteins, enzymes, and macromolecular complexes comprising these species. Determination of pairwise interactions of alkali metal cations with amino acids provides a thermodynamic vocabulary that begins to quantify these fundamental processes. In the present work, we expand a systematic study of such interactions by examining rubidium and cesium cations binding with the acidic amino acids (AA), aspartic acid (Asp) and glutamic acid (Glu), and their amide derivatives, asparagine (Asn) and glutamine (Gln). These eight complexes are formed using electrospray ionization and their bond dissociation energies (BDEs) are determined experimentally using threshold collision-induced dissociation with xenon in a guided ion beam tandem mass spectrometer. Analyses of the energy-dependent cross sections include consideration of unimolecular decay rates, internal energy of the reactant ions, and multiple ion-neutral collisions. Quantum chemical calculations are conducted at the B3LYP, MP2(full), and M06 levels of theory using def2-TZVPPD basis sets, with results showing reasonable agreement with experiment. At 0 and 298 K, most levels of theory predict that the ground-state conformers for M(+)(Asp) and M(+)(Asn) involve tridentate binding of the metal cation to the backbone carbonyl, amino, and side-chain carbonyl groups, although tridentate binding to the carboxylic acid group and side-chain carbonyl is competitive for M(+)(Asn). For the two longer side-chain amino acids, Glu and Gln, multiple structures are competitive. A comparison of these results to those for the smaller alkali cations, Na(+) and K(+), provides insight into the trends in binding energies associated with the molecular polarizability and dipole moment of the side chain. For all four metal cations, the BDEs are inversely correlated with the size of the metal cation and follow the order Asp < Glu

  1. Understanding the complexity of trans fatty acid reduction in the American diet: American Heart Association Trans Fat Conference 2006: report of the Trans Fat Conference Planning Group.

    PubMed

    Eckel, Robert H; Borra, Susan; Lichtenstein, Alice H; Yin-Piazza, Shirley Y

    2007-04-24

    A 2-day forum was convened to discuss the current status and future implications of reducing trans fatty acids without increasing saturated fats in the food supply while maintaining functionality and consumer acceptance of packaged, processed, and prepared foods. Attendees represented the agriculture and oilseed industry and oil processing, food manufacturing, food service, government, food technology, and health and nutrition disciplines. Presentations included food science behind fatty acid technology, the health science of dietary fatty acids, alternatives to trans fatty acids, and the use of alternatives in food manufacturing and food service. The reduction of trans fatty acids in the food supply is a complex issue involving interdependent and interrelated stakeholders. Actions to reduce trans fatty acids need to carefully consider both intended and unintended consequences related to nutrition and public health. The unintended consequence of greatest concern is that fats and oils high in saturated fats, instead of the healthier unsaturated fats, might be used to replace fats and oils with trans fatty acids. Many different options of alternative oils and fats to replace trans fatty acids are available or in development. Decisions on the use of these alternatives need to consider availability, health effects, research and development investments, reformulated food quality and taste, supply-chain management, operational modifications, consumer acceptance, and cost. The conference demonstrated the value of collaboration between the food industry and health and nutrition professionals, and this conference model should be used to address other food development, processing, and/or technology issues.

  2. Transient Adverse Side Effects During Neurofeedback Training: A Randomized, Sham-Controlled, Double Blind Study.

    PubMed

    Rogel, Ainat; Guez, Jonathan; Getter, Nir; Keha, Eldad; Cohen, Tzlil; Amor, Tali; Todder, Doron

    2015-09-01

    The benefits of clinical neurofeedback training are well known, however, its adverse side-effects are less studied. This research focuses on the transient adverse side effects of neurofeedback training via a double-blind, sham/controlled methodology. Thirty healthy undergraduate students volunteers were randomly divided into three treatment groups: increasing a modified Sensory Motor Rhythm, increasing Upper Alpha, and Sham/control group who receive a random reward. The training sessions were administered for a total of ten sessions. Questionnaires of transient adverse side effects were completed by all volunteers before each session. The results suggest that similar to most medical treatments, neurofeedback can cause transient adverse side effects. Moreover, most participants reported experiencing some side effects. The side effects can be divided into non-specific side effect, associated with the neurofeedback training in general and specific ones associated with the particular protocol. Sensory Motor Rhythm protocol seems to be the most sensitive to side effects.

  3. [Coronary artery bypass grafting using side-to-side anastomosis].

    PubMed

    Niinami, H; Takeuchi, Y

    2000-08-01

    Recently, to obtain better long-term patency after coronary artery bypass grafting (CABG) arterial conduits such as internal mammary arteries (IMAs) and the right gastroepiploic artery have been frequently used. For coronary site anastomosis, end-to-side anastomosis is common. These conduits have a smaller diameter than the saphenous vein graft, so that, usually, longitudinal slits are made on the distal end of these grafts to obtain a more effective anastomotic orifice area. However, there is a potential for anastomotic leakage due to mismatch between the incision of the coronary artery and the arterial graft. We report here the efficacy of side-to-side anastomosis using small arterial conduits. This method has several advantages. Firstly, there is no chance of anastomotic leakage, since the coronary incision and graft incision can be perfectly matched. Secondly, if there is at least a 5-mm distance between the distal end of the graft incision and the surgical clip, the graft incision can be extended during anastomosis for adjustment. Thirdly, the distal end of the graft can be held beyond the surgical clip by forceps without damaging the arterial graft, which makes it easier for the anastomosis to be performed. Finally, the anastomosis can be checked by passing a probe through the distal end of the graft after removing the surgical clip. Also dye can be injected from the distal end of the graft at "Off Pump CABG", intraoperatively. This technique can be applied not only for distal end anastomosis, but also for proximal end, using free IMA to the ascending aorta and to make a Y-graft.

  4. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  5. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  6. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  7. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  8. 49 CFR 229.69 - Side bearings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  9. Side gear mounting for differential assembly

    SciTech Connect

    Pederson, H.

    1989-02-21

    A differential gear assembly is described of the type which includes a differential gear housing having means for receiving a pair of axle ends together with a pair of substantially axially aligned side gears coupled to the pair of axle ends for rotation therewith, the side gears having helix angles inclined in the same direction with respect to the axes of rotation thereof, characterized in that the gear assembly includes means for preventing axial thrust forces developed by one of the side gears from loading the other of the side gears. The preventing means includes means for separating the side gears such that there is no direct or indirect engagement between confronting end faces of the side gears when thrust forces of one of the side gears are directed toward the other of the side gears; and the means for axially separating the side gears includes a pair of overlapping elements associated with one of the side gears of the gear housing.

  10. Development of a complex amino acid supplement, Fatigue Reviva™, for oral ingestion: initial evaluations of product concept and impact on symptoms of sub-health in a group of males

    PubMed Central

    2013-01-01

    Background A new dietary supplement, Fatigue Reviva™, has been recently developed to address issues related to amino acid depletion following illness or in conditions of sub-health where altered amino acid homeostasis has been associated with fatigue. Complex formulations of amino acids present significant challenges due to solubility and taste constraints. This initial study sets out to provide an initial appraisal of product palatability and to gather pilot evidence for efficacy. Methods Males reporting symptoms of sub-health were recruited on the basis of being free from any significant medical or psychological condition. Each participant took an amino acid based dietary supplement (Fatigue Reviva™) daily for 30 days. Comparisons were then made between pre- and post-supplement general health symptoms and urinary amino acid profiles. Results Seventeen men took part in the study. Following amino acid supplementation the total Chalder fatigue score improved significantly (mean ± SEM, 12.5 ± 0.9 versus 10.0 ± 1.0, P<0.03). When asked whether they thought that the supplement had improved their health, 65% of participants responded positively. A subgroup of participants reported gastrointestinal symptoms which were attributed to the supplement and which were believed to result from the component fructooligosaccharide. Analysis of urinary amino acids revealed significant alterations in the relative abundances of a number of amino acids after supplementation including an increase in valine, isoleucine and glutamic acid and reduced levels of glutamine and ornithine. Discriminant function analysis of the urinary amino acid data revealed significant differences between the pre- and post-supplement urine excretion profiles. Conclusions The results indicated that Fatigue Reviva™ was palatable and that 65% of the study group reported that they felt the product had improved their health. The product could provide an effective tool for the management of unexplained

  11. Two Droplets Burning Side by Side on MSL-1R

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Fiber-Supported Droplet Combustion (FSDC) experiment team got more than twice as many burns have been completed as were originally scheduled for STS-95. This image was taken July 12, 1997, MET:10/08:13 (approximate). As shown here, scientists were able to burn two droplets side by side, more closely mimicking behavior of burning fuel in an engine. This shows ignition of a single drop that subsequently burned while a fan blew through the chamber, giving the scientists data on burning with convection, but no buoyancy -- an important distinction when you're trying to solve a problem by breaking it into parts. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (200KB JPEG, 1171 x 1319 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300177.html.

  12. Determinants of protein side-chain packing.

    PubMed Central

    Tanimura, R.; Kidera, A.; Nakamura, H.

    1994-01-01

    The problem of protein side-chain packing for a given backbone trace is investigated using 3 different prediction models. The first requires an exhaustive search of all possible combinations of side-chain conformers, using the dead-end elimination theorem. The second considers only side-chain-backbone interactions, whereas the third neglects side-chain-backbone interactions and instead keeps side-chain-side-chain interactions. Predictions of side-chain conformations for 11 proteins using all 3 models show that removal of side-chain-side-chain interactions does not cause a large decrease in the prediction accuracy, whereas the model having only side-chain-side-chain interactions still retains a significant level of accuracy. These results suggest that the 2 classes of interactions, side-chain-backbone and side-chain-side-chain, are consistent with each other and work concurrently to stabilize the native conformations. This is confirmed by analyses of energy spectra of the side-chain conformations derived from the fourth prediction model, the Independent model, which gives almost the same quality of the prediction as the dead-end elimination. The analyses indicate that the 2 classes of interactions simultaneously increase the energy difference between the native and nonnative conformations. PMID:7756990

  13. Side effects of stimulant use.

    PubMed

    Levy, F

    1993-08-01

    The current literature on side effects of central nervous system (CNS) stimulant medications used in the treatment of attention deficit hyperactivity disorder (ADHD) is reviewed, with particular emphasis on dose-response effects on differing behavioural systems. The reasons for variation in findings may lie in individual differences in children, or in differing responses of target behavioural systems. These may be understood in terms of underlying pharmacological mechanisms. Social, educational and philosophical issues relating to medication use are discussed, and the need for ongoing critical clinical and research approaches, rather than polarization of professional attitudes, is emphasized.

  14. Demand Side Bidding. Final Report

    SciTech Connect

    Spahn, Andrew

    2003-12-31

    This document sets forth the final report for a financial assistance award for the National Association of Regulatory Utility Commissioners (NARUC) to enhance coordination between the building operators and power system operators in terms of demand-side responses to Location Based Marginal Pricing (LBMP). Potential benefits of this project include improved power system reliability, enhanced environmental quality, mitigation of high locational prices within congested areas, and the reduction of market barriers for demand-side market participants. NARUC, led by its Committee on Energy Resources and the Environment (ERE), actively works to promote the development and use of energy efficiency and clean distributive energy policies within the framework of a dynamic regulatory environment. Electric industry restructuring, energy shortages in California, and energy market transformation intensifies the need for reliable information and strategies regarding electric reliability policy and practice. NARUC promotes clean distributive generation and increased energy efficiency in the context of the energy sector restructuring process. NARUC, through ERE's Subcommittee on Energy Efficiency, strives to improve energy efficiency by creating working markets. Market transformation seeks opportunities where small amounts of investment can create sustainable markets for more efficient products, services, and design practices.

  15. Preparation of Two New Diasteromeric Chiral Stationary Phases Based on (+)-(18-Crown-6)-2,3,11,12-tetracarboxylic Acid and (R)- or (S)-1-(1-Naphthyl)ethylamine and Chiral Tethering Group Effect on the Chiral Recognition.

    PubMed

    Agneeswari, Rajalingam; Sung, Ji Yeong; Jo, Eun Sol; Jeon, Hee Young; Tamilavan, Vellaiappillai; Hyun, Myung Ho

    2016-08-12

    Two new diastereomeric chiral stationary phases (CSPs) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid as a chiral tethering group and a Π-basic chiral unit such as (R)-1-(1-naphthyl)ethylamine (CSP 1) or (S)-1-(1-naphthyl)ethylamine (CSP 2) were prepared. The two CSPs were applied to the enantiomeric separation of N-(3,5-dinitrobenzoyl)-1-phenylalkylamines and N-(3,5-dinitrobenzoyl)-α-amino acid derivatives using 20% isopropyl alcohol in hexane as a normal mobile phase. To elucidate the effect of the two chiral units on the chiral recognition, the chiral recognition abilities of the two CSPs were compared with each other and with that of a CSP (CSP 3) based on (R)-1-(1-naphthyl)ethylamine. From the chromatographic chiral recognition results, (R)-1-(1-naphthyl)ethylamine and (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid constituting CSP 1 were concluded to show a cooperative ("matched") effect on the chiral recognition while (S)-1-(1-naphthyl)ethylamine and (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid constituting CSP 2 were concluded to show an uncooperative ("mismatched") effect on the chiral recognition. From these results, it was concluded that (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid can be successfully used as a chiral tethering group for the preparation of new CSPs.

  16. 5. West SideElevated Tank Structure with fume exhaust system and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. West Side-Elevated Tank Structure with fume exhaust system and support structure in foreground. - Mare Island Naval Shipyard, Acid Mixing Facility, California Avenue & E Street, Vallejo, Solano County, CA

  17. Synthesis and Electrochemical and Photophysical Characterization of New 4,4'-π-Conjugated 2,2'-Bipyridines that are End-Capped with Cyanoacrylic Acid/Ester Groups.

    PubMed

    Fingerhut, Anja; Wu, Yanlin; Kahnt, Axel; Bachmann, Julien; Tsogoeva, Svetlana B

    2016-04-20

    Two new functionalized 4,4'-disubstituted 2,2'-bipyridines that were end-capped with cyanoacrylic acid or cyanoacrylic acid ester anchoring groups, which might allow their efficient functionalization on TiO2 or other metal-oxide semiconductor surfaces, have been synthesized and characterized by electrochemical, photophysical, and spectroscopic measurements. The electrochemical and photophysical properties of these 4,4'-disubstituted 2,2'-bipyridines with extended π systems, in particular their LUMO energies, make them promising candidates to build up inorganic-organic hybrid photosensitizers for the sensitization of metal-oxide semiconductors (e.g., TiO2 nanoparticles and/or nanotubes).

  18. Comparison of Peripheral Nerve Regeneration with Side-to-side, End-to-side, and End-to-end Repairs: An Experimental Study

    PubMed Central

    Göransson, Harry; Taskinen, Hanna-Stiina; Paavilainen, Pasi; Vahlberg, Tero; Röyttä, Matias

    2016-01-01

    Background: The present study was conducted to find out a tool to enable improved functional recovery with proximal nerve injury. In this experimental study, nerve regeneration was compared between side-to-side (STS), end-to-side (ETS), and end-to-end repairs. Methods: The walk track analysis was used as an outcome of functional recovery. Nerve regeneration was studied with morphometry and histology 6 or 26 weeks postoperatively. Results: All 3 repair techniques showed regeneration of the nerve. From 12 weeks onward, the functional results of the 3 intervention groups were significantly better compared with the unrepaired control group. End-to-end repair was significantly better when compared with the STS and ETS groups. At 26 weeks, the functional and morphometric results and histologic findings did not differ between the STS and ETS groups. The functional results correlated with the morphometric findings in all <