Science.gov

Sample records for alkyl chain branching

  1. Mössbauer study of novel iron(II)-dioxime complexes with branched alkyl chains

    NASA Astrophysics Data System (ADS)

    Kuzmann, E.; Lengyel, A.; Homonnay, Z.; Várhelyi, Cs.; Klencsár, Z.; Kubuki, S.; Szalay, R.

    2014-04-01

    Novel iron(II) oxime complexes with dimethyl-glyoxime, methyl-ethyl-glyoxime, methyl-isopropyl-glyoxime, [Fe(DioxH)2L2] with and without axial ligands have been synthesized. 57Fe Mössbauer spectroscopy showed different spin states in complexes with short alkyl chain and with branched alkyl chain, respectively. It was shown that the asymmetry observed in the doublet line intensity of iron-bis-glyoximes is due to the texture effect. The effect of back-coordination was also studied in the case of iron-bis-dioxime complexes with branched alkyl chains, having different axial ligands.

  2. Activated-sludge nitrification in the presence of linear and branched-chain alkyl benzene sulfonates.

    PubMed

    Baillod, C R; Boyle, W C

    1968-01-01

    The effects of biodegradable linear alkyl benzene sulfonate and branched-chain alkyl benzene sulfonate detergents on activated-sludge nitrification were investigated by administering a synthetic waste containing up to 23 mg of each detergent per liter to eight bench-scale, batch, activated-sludge units. It was found that both detergents tended to promote complete oxidation of ammonia to nitrate, whereas control units produced approximately equal amounts of nitrite and nitrate. Various hypotheses are offered to explain the phenomenon.

  3. 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

  4. Bis(thienothiophenyl) diketopyrrolopyrrole-based conjugated polymers with various branched alkyl side chains and their applications in thin-film transistors and polymer solar cells.

    PubMed

    Shin, Jicheol; Park, Gi Eun; Lee, Dae Hee; Um, Hyun Ah; Lee, Tae Wan; Cho, Min Ju; Choi, Dong Hoon

    2015-02-11

    New thienothiophene-flanked diketopyrrolopyrrole and thiophene-containing π-extended conjugated polymers with various branched alkyl side-chains were successfully synthesized. 2-Octyldodecyl, 2-decyltetradecyl, 2-tetradecylhexadecyl, 2-hexadecyloctadecyl, and 2-octadecyldocosyl groups were selected as the side-chain moieties and were anchored to the N-positions of the thienothiophene-flanked diketopyrrolopyrrole unit. All five polymers were found to be soluble owing to the bulkiness of the side chains. The thin-film transistor based on the 2-tetradecylhexadecyl-substituted polymer showed the highest hole mobility of 1.92 cm2 V(-1) s(-1) due to it having the smallest π-π stacking distance between the polymer chains, which was determined by grazing incidence X-ray diffraction. Bulk heterojunction polymer solar cells incorporating [6,6]-phenyl-C71-butyric acid methyl ester as the n-type molecule and the additive 1,8-diiodooctane (1 vol %) were also constructed from the synthesized polymers without thermal annealing; the device containing the 2-octyldodecyl-substituted polymer exhibited the highest power conversion efficiency of 5.8%. Although all the polymers showed similar physical properties, their device performance was clearly influenced by the sizes of the branched alkyl side-chain groups.

  5. Solubility of n-butane and 2-methylpropane (isobutane) in 1-alkyl-3-methylimidazolium-based ionic liquids with linear and branched alkyl side-chains.

    PubMed

    Pison, Laure; Shimizu, Karina; Tamas, George; Lopes, José Nuno Canongia; Quitevis, Edward L; Gomes, Margarida F Costa

    2015-11-11

    The solubility of n-butane and 2-methylpropane (isobutane) in three ionic liquids - 1-(2-methylpropyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [(2mC3)C1im][Ntf2], 1-(3-methylbutyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [(3mC4)C1im][Ntf2] and 1-methyl-3-pentylimidazolium bis(trifluoromethylsulfonyl)imide [C5C1im][Ntf2] - has been measured at atmospheric pressure from 303 to 343 K. Isobutane is less soluble than n-butane in all the ionic liquids. Henry's constant values range from 13.8 × 10(5) Pa for n-butane in [C5C1im][Ntf2] at 303 K to 64.5 × 10(5) Pa for isobutane in [(2mC3)C1im][Ntf2] at 343 K. The difference in solubility between the two gases can be explained by a more negative enthalpy of solvation for n-butane. A structural analysis of the pure solvents and of the solutions of the gases, probed by molecular dynamics simulations, could explain the differences found in the systems: (i) the nonpolar domains of the ionic liquids accommodate better the long and more flexible n-butane solute; (ii) the small differences in solubility of each gas in the ionic liquids with the same number of carbon atoms in the alkyl side-chains are explained by the absence of large structural differences in the pure solvents. In all cases, the structural analysis of the four ionic liquids confirms that the studied gases can act as probes of the molecular structure of the ionic liquids, the simulations being always compatible with the experimental solubility data.

  6. Solubility of n-butane and 2-methylpropane (isobutane) in 1-alkyl-3-methylimidazolium-based ionic liquids with linear and branched alkyl side-chains.

    PubMed

    Pison, Laure; Shimizu, Karina; Tamas, George; Lopes, José Nuno Canongia; Quitevis, Edward L; Gomes, Margarida F Costa

    2015-11-11

    The solubility of n-butane and 2-methylpropane (isobutane) in three ionic liquids - 1-(2-methylpropyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [(2mC3)C1im][Ntf2], 1-(3-methylbutyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [(3mC4)C1im][Ntf2] and 1-methyl-3-pentylimidazolium bis(trifluoromethylsulfonyl)imide [C5C1im][Ntf2] - has been measured at atmospheric pressure from 303 to 343 K. Isobutane is less soluble than n-butane in all the ionic liquids. Henry's constant values range from 13.8 × 10(5) Pa for n-butane in [C5C1im][Ntf2] at 303 K to 64.5 × 10(5) Pa for isobutane in [(2mC3)C1im][Ntf2] at 343 K. The difference in solubility between the two gases can be explained by a more negative enthalpy of solvation for n-butane. A structural analysis of the pure solvents and of the solutions of the gases, probed by molecular dynamics simulations, could explain the differences found in the systems: (i) the nonpolar domains of the ionic liquids accommodate better the long and more flexible n-butane solute; (ii) the small differences in solubility of each gas in the ionic liquids with the same number of carbon atoms in the alkyl side-chains are explained by the absence of large structural differences in the pure solvents. In all cases, the structural analysis of the four ionic liquids confirms that the studied gases can act as probes of the molecular structure of the ionic liquids, the simulations being always compatible with the experimental solubility data. PMID:26506981

  7. Molecular Packing of High-Mobility Diketo Pyrrolo-Pyrrole Polymer Semiconductors with Branched Alkyl Side Chains

    SciTech Connect

    X Zhang; L Richter; D DeLongchamp; R Kline; M Hammond; I McCulloch; M Heeney; R Ashraf; J Smith; et al.

    2011-12-31

    We describe a series of highly soluble diketo pyrrolo-pyrrole (DPP)-bithiophene copolymers exhibiting field effect hole mobilities up to 0.74 cm{sup 2} V{sup -1} s{sup -1}, with a common synthetic motif of bulky 2-octyldodecyl side groups on the conjugated backbone. Spectroscopy, diffraction, and microscopy measurements reveal a transition in molecular packing behavior from a preferentially edge-on orientation of the conjugated plane to a preferentially face-on orientation as the attachment density of the side chains increases. Thermal annealing generally reduces both the face-on population and the misoriented edge-on domains. The highest hole mobilities of this series were obtained from edge-on molecular packing and in-plane liquid-crystalline texture, but films with a bimodal orientation distribution and no discernible in-plane texture exhibited surprisingly comparable mobilities. The high hole mobility may therefore arise from the molecular packing feature common to the entire polymer series: backbones that are strictly oriented parallel to the substrate plane and coplanar with other backbones in the same layer.

  8. C18-unsaturated branched-chain fatty acid isomers: characterization and physical properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Iso-oleic acid is a mixture of C18-unsaturated branched-chain fatty acid isomers with a methyl group on various positions of the alkyl chain, which is the product of the skeletal isomerization reaction of oleic acid and is the intermediate used to make isostearic acid (C18-saturated branched-chain f...

  9. Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanide

    NASA Astrophysics Data System (ADS)

    Belloche, Arnaud; Garrod, Robin T.; Müller, Holger S. P.; Menten, Karl M.

    2014-09-01

    The largest noncyclic molecules detected in the interstellar medium (ISM) are organic with a straight-chain carbon backbone. We report an interstellar detection of a branched alkyl molecule, iso-propyl cyanide (i-C3H7CN), with an abundance 0.4 times that of its straight-chain structural isomer. This detection suggests that branched carbon-chain molecules may be generally abundant in the ISM. Our astrochemical model indicates that both isomers are produced within or upon dust grain ice mantles through the addition of molecular radicals, albeit via differing reaction pathways. The production of iso-propyl cyanide appears to require the addition of a functional group to a nonterminal carbon in the chain. Its detection therefore bodes well for the presence in the ISM of amino acids, for which such side-chain structure is a key characteristic.

  10. 40 CFR 721.10218 - 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-branched and linear alkyl esters, telomers with alkyl 2- thio]-2-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated (generic). 721.10218 Section 721.10218... 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2-...

  11. 40 CFR 721.10218 - 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-branched and linear alkyl esters, telomers with alkyl 2- thio]-2-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated (generic). 721.10218 Section 721.10218... 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2-...

  12. 40 CFR 721.10218 - 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-branched and linear alkyl esters, telomers with alkyl 2- thio]-2-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated (generic). 721.10218 Section 721.10218... 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2-...

  13. 40 CFR 721.10218 - 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-branched and linear alkyl esters, telomers with alkyl 2- thio]-2-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated (generic). 721.10218 Section 721.10218... 2-Propenoic acid, 2-mehtyl-, C12-15-branched and linear alkyl esters, telomers with alkyl 2-...

  14. Thiophene-Diketopyrrolopyrrole-Based Quinoidal Small Molecules as Solution-Processable and Air-Stable Organic Semiconductors: Tuning of the Length and Branching Position of the Alkyl Side Chain toward a High-Performance n-Channel Organic Field-Effect Transistor.

    PubMed

    Wang, Chao; Qin, Yunke; Sun, Yuanhui; Guan, Ying-Shi; Xu, Wei; Zhu, Daoben

    2015-07-29

    A series of thiophene-diketopyrrolopyrrole-based quinoidal small molecules (TDPPQ-2-TDPPQ-5) bearing branched alkyl chains with different side-chain lengths and varied branching positions are synthesized. Field-effect transistor (FET) measurement combined with thin-film characterization is utilized to systematically probe the influence of the side-chain length and branching position on the film microstructure, molecular packing, and, hence, charge-transport property. All of these TDPPQ derivatives show air-stable n-channel transporting behavior in spin-coated FET devices, which exhibit no significant decrease in mobility even after being stored in air for 2 months. Most notably, TDPPQ-3 exhibits an outstanding n-channel semiconducting property with electron mobilities up to 0.72 cm(2) V(-1) s(-1), which is an unprecedented value for spin-coated DPP-based n-type semiconducting small molecules. A balance of high crystallinity, satisfactory thickness uniformity and continuity, and strong intermolecular interaction accounts for the superior charge-transport characteristics of TDPPQ-3 films. Our study demonstrates that tuning the length and branching position of alkyl side chains of semiconducting molecules is a powerful strategy for achieving high FET performance. PMID:26134920

  15. 40 CFR 721.10143 - Amines, bis (C11-14-branched and linear alkyl).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... linear alkyl). 721.10143 Section 721.10143 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10143 Amines, bis (C11-14-branched and linear alkyl). (a) Chemical..., bis (C11-14-branched and linear alkyl) (PMN P-06-733; CAS No. 900169-60-0) is subject to...

  16. 40 CFR 721.10143 - Amines, bis (C11-14-branched and linear alkyl).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... linear alkyl). 721.10143 Section 721.10143 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10143 Amines, bis (C11-14-branched and linear alkyl). (a) Chemical..., bis (C11-14-branched and linear alkyl) (PMN P-06-733; CAS No. 900169-60-0) is subject to...

  17. 40 CFR 721.10350 - Amines, C11-14-branched and linear alkyl.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... alkyl. 721.10350 Section 721.10350 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.10350 Amines, C11-14-branched and linear alkyl. (a) Chemical substance...-branched and linear alkyl (PMN P-06-742; CAS No. 863766-30-7) is subject to reporting under this...

  18. 40 CFR 721.10143 - Amines, bis (C11-14-branched and linear alkyl).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... linear alkyl). 721.10143 Section 721.10143 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10143 Amines, bis (C11-14-branched and linear alkyl). (a) Chemical..., bis (C11-14-branched and linear alkyl) (PMN P-06-733; CAS No. 900169-60-0) is subject to...

  19. 40 CFR 721.10143 - Amines, bis (C11-14-branched and linear alkyl).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... linear alkyl). 721.10143 Section 721.10143 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10143 Amines, bis (C11-14-branched and linear alkyl). (a) Chemical..., bis (C11-14-branched and linear alkyl) (PMN P-06-733; CAS No. 900169-60-0) is subject to...

  20. 40 CFR 721.10143 - Amines, bis (C11-14-branched and linear alkyl).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... linear alkyl). 721.10143 Section 721.10143 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10143 Amines, bis (C11-14-branched and linear alkyl). (a) Chemical..., bis (C11-14-branched and linear alkyl) (PMN P-06-733; CAS No. 900169-60-0) is subject to...

  1. 40 CFR 721.10350 - Amines, C11-14-branched and linear alkyl.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... alkyl. 721.10350 Section 721.10350 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.10350 Amines, C11-14-branched and linear alkyl. (a) Chemical substance...-branched and linear alkyl (PMN P-06-742; CAS No. 863766-30-7) is subject to reporting under this...

  2. 40 CFR 721.10350 - Amines, C11-14-branched and linear alkyl.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... alkyl. 721.10350 Section 721.10350 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.10350 Amines, C11-14-branched and linear alkyl. (a) Chemical substance...-branched and linear alkyl (PMN P-06-742; CAS No. 863766-30-7) is subject to reporting under this...

  3. Preparation of quinolinium salts differing in the length of the alkyl side chain.

    PubMed

    Marek, Jan; Buchta, Vladimir; Soukup, Ondrej; Stodulka, Petr; Cabal, Jiri; Ghosh, Kallol K; Musilek, Kamil; Kuca, Kamil

    2012-05-25

    Quaternary quinolinium salts differing in alkyl chain length are members of a widespread group of cationic surfactants. These compounds have numerous applications in various branches of industry and research. In this work, the preparation of quinoline-derived cationic surface active agents differing in the length of the side alkyl chains (from C₈ to C₂₀) is described. An HPLC method was successfully developed for distinction of all members of the series of prepared long-chain quinolinium derivatives. In conclusion, some possibilities of intended tests or usage have been summarized. In vitro testing using a microdilution broth method showed good activity of a substance with a C12 chain length against Gram-positive cocci and Candida species.

  4. Melting at Alkyl Side Chain Comb Polymer Interfaces

    NASA Astrophysics Data System (ADS)

    Gautam, Keshav; Dhinojwala, Ali

    2002-03-01

    IR-visible sum-frequency generation (SFG) in combination with internal reflection geometry has been used to study structure and melting transition temperatures of alkyl side chain acrylate comb polymers at air and sapphire interfaces. At the air interface, the SFG spectra show methyl bands and two transitions are observed. The first transition from crystalline to smectic-like is near the bulk melting transition, Tm, and the second transition from smectic-like to disordered melt state is 10-20K higher than Tm. The shorter the alkyl side chain, the larger the difference between the two transition temperatures. In contrast, methylene bands are observed at sapphire interface with a single transition near Tm. These results will be discussed in context with surface freezing effects observed for n-alkanes and alcohols.

  5. Branch-Selective Alkene Hydroarylation by Cooperative Destabilization: Iridium-Catalyzed ortho-Alkylation of Acetanilides.

    PubMed

    Crisenza, Giacomo E M; Sokolova, Olga O; Bower, John F

    2015-12-01

    An iridium(I) catalyst system, modified with the wide-bite-angle and electron-deficient bisphosphine d(F) ppb (1,4-bis(di(pentafluorophenyl)phosphino)butane) promotes highly branch-selective hydroarylation reactions between diverse acetanilides and aryl- or alkyl-substituted alkenes. This provides direct and ortho-selective access to synthetically challenging anilines, and addresses long-standing issues associated with related Friedel-Crafts alkylations. PMID:26490739

  6. Branch-Selective Alkene Hydroarylation by Cooperative Destabilization: Iridium-Catalyzed ortho-Alkylation of Acetanilides

    PubMed Central

    Crisenza, Giacomo E M; Sokolova, Olga O; Bower, John F

    2015-01-01

    An iridium(I) catalyst system, modified with the wide-bite-angle and electron-deficient bisphosphine dFppb (1,4-bis(di(pentafluorophenyl)phosphino)butane) promotes highly branch-selective hydroarylation reactions between diverse acetanilides and aryl- or alkyl-substituted alkenes. This provides direct and ortho-selective access to synthetically challenging anilines, and addresses long-standing issues associated with related Friedel–Crafts alkylations. PMID:26490739

  7. Diketopyrrolopyrrole-based Conjugated Polymers Bearing Branched Oligo(Ethylene Glycol) Side Chains for Photovoltaic Devices.

    PubMed

    Chen, Xingxing; Zhang, Zijian; Ding, Zicheng; Liu, Jun; Wang, Lixiang

    2016-08-22

    Conjugated polymers are essential for solution-processable organic opto-electronic devices. In contrast to the great efforts on developing new conjugated polymer backbones, research on developing side chains is rare. Herein, we report branched oligo(ethylene glycol) (OEG) as side chains of conjugated polymers. Compared with typical alkyl side chains, branched OEG side chains endowed the resulting conjugated polymers with a smaller π-π stacking distance, higher hole mobility, smaller optical band gap, higher dielectric constant, and larger surface energy. Moreover, the conjugated polymers with branched OEG side chains exhibited outstanding photovoltaic performance in polymer solar cells. A power conversion efficiency of 5.37 % with near-infrared photoresponse was demonstrated and the device performance could be insensitive to the active layer thickness.

  8. Tunneling conductance of amine-linked alkyl chains.

    PubMed

    Prodan, Emil; Car, Roberto

    2008-06-01

    The tunneling transport theory developed in ref 9 (Phys. Rev. B 2007, 76, 115102) is applied to molecular devices made of alkyl chains linked to gold electrodes via amine groups. Using the analytic expression of the tunneling conductance derived in our previous work, we identify the key physical quantities that characterize the conductance of these devices. By investigating the transport characteristics of three devices, containing four, six, and eight methyl groups, we extract the dependence of the tunneling conductance on the chain's length, which is an exponential decay law in agreement with recent experimental data.

  9. 40 CFR 721.10025 - 10H-Phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... C8-10-branched alkyl) derivs. 721.10025 Section 721.10025 Protection of Environment ENVIRONMENTAL...-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified as 10H-phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  10. 40 CFR 721.10025 - 10H-Phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... C8-10-branched alkyl) derivs. 721.10025 Section 721.10025 Protection of Environment ENVIRONMENTAL...-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified as 10H-phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  11. 40 CFR 721.10022 - Benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... C8-10-branched alkyl) derivs. 721.10022 Section 721.10022 Protection of Environment ENVIRONMENTAL...-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  12. 40 CFR 721.10022 - Benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... C8-10-branched alkyl) derivs. 721.10022 Section 721.10022 Protection of Environment ENVIRONMENTAL...-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  13. 40 CFR 721.10025 - 10H-Phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... C8-10-branched alkyl) derivs. 721.10025 Section 721.10025 Protection of Environment ENVIRONMENTAL...-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified as 10H-phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  14. 40 CFR 721.10025 - 10H-Phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... C8-10-branched alkyl) derivs. 721.10025 Section 721.10025 Protection of Environment ENVIRONMENTAL...-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified as 10H-phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  15. 40 CFR 721.10022 - Benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... C8-10-branched alkyl) derivs. 721.10022 Section 721.10022 Protection of Environment ENVIRONMENTAL...-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  16. 40 CFR 721.10022 - Benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... C8-10-branched alkyl) derivs. 721.10022 Section 721.10022 Protection of Environment ENVIRONMENTAL...-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  17. 40 CFR 721.10025 - 10H-Phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... C8-10-branched alkyl) derivs. 721.10025 Section 721.10025 Protection of Environment ENVIRONMENTAL...-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified as 10H-phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  18. 40 CFR 721.10022 - Benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... C8-10-branched alkyl) derivs. 721.10022 Section 721.10022 Protection of Environment ENVIRONMENTAL...-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  19. Interfacial assignment of branched-alkyl benzene sulfonates: A molecular simulation

    NASA Astrophysics Data System (ADS)

    Liu, Zi-Yu; Wei, Ning; Wang, Ce; Zhou, He; Zhang, Lei; Liao, Qi; Zhang, Lu

    2015-11-01

    A molecular dynamics simulation was conducted to analyze orientations of sodium branched-alkyl benzene sulfonates molecules at nonane/water interface, which is helpful to design optimal surfactant structures to achieve ultralow interfacial tension (IFT). Through the two dimensional density profiles, monolayer collapses are found when surfactant concentration continues to increase. Thus the precise scope of monolayer is certain and orientation can be analyzed. Based on the simulated results, we verdict the interfacial assignment of branched-alkyl benzene sulfonates at the oil-water interface, and discuss the effect of hydrophobic tail structure on surfactant assignment. Bigger hydrophobic size can slow the change rate of surfactant occupied area as steric hindrance, and surfactant meta hydrophobic tails have a stronger tendency to stretch to the oil phase below the collapsed concentration. Furthermore, an interfacial model with reference to collapse, increasing steric hindrance and charge repulsive force between interfacial surfactant molecules, responsible for effecting of surfactant concentration and structure has been supposed.

  20. Radiolabeled dimethyl branched long chain fatty acid for heart imaging

    DOEpatents

    Knapp, Jr., Furn F.; Goodman, Mark M.; Kirsch, Gilbert

    1988-08-16

    A radiolabeled long chain fatty acid for heart imaging that has dimethyl branching at one of the carbons of the chain which inhibits the extent to which oxidation can occur. The closer to the carboxyl the branching is positioned, the more limited the oxidation, thereby resulting in prolonged retention of the radiolabeled compound in the heart.

  1. Growth of Highly Oriented Ultrathin Crystalline Organic Microstripes: Effect of Alkyl Chain Length.

    PubMed

    Zhu, Tao; Xiao, Chengliang; Wang, Binghao; Hu, Xiaorong; Wang, Zi; Fan, Jian; Huang, Lizhen; Yan, Donghang; Chi, Lifeng

    2016-09-13

    The growth of organic semiconductor with controllable morphology is a crucial issue for achieving high-performance devices. Here we present the systematic study of the effect of the alkyl chain attached to the functional entity on controlling the growth of oriented microcrystals by dip-coating. Alkylated DTBDT-based molecules with variable chain lengths from n-butyl to n-dodecyl formed into one-dimensional micro- or nanostripe crystals at different pulling speeds. The alignment and ordering are significantly varied with alkyl chain length, as is the transistor performance. Highly uniform oriented and higher-molecular-order crystalline stripes with improved field-effect mobility can be achieved with an alkyl-chain length of around 6. We attribute this effect to the alkyl-chain-length-dependent packing, solubility, and self-assembly behavior. PMID:27548053

  2. Confinement-induced order of tethered alkyl chains at the water/vapor interface.

    PubMed

    Fukuto, M; Heilmann, R K; Pershan, P S; Yu, S M; Soto, C M; Tirrell, D A

    2002-07-01

    Packing of tethered alkyl chains in Langmuir monolayers of a hairy-rod polypeptide poly[gamma-4-(n-hexadecyloxy)benzyl alpha,L-glutamate] on water has been studied by x-ray scattering measurements at room temperature. The rods lie parallel to the surface while the alkyl side chains segregate toward the vapor. Results indicate that the herringbone order of the alkyl chains is established initially by one-dimensionally confined chains between aligned rods and grows laterally with compression. PMID:12241332

  3. Role of mitochondrial transamination in branched chain amino acid metabolism

    SciTech Connect

    Hutson, S.M.; Fenstermacher, D.; Mahar, C.

    1988-03-15

    Oxidative decarboxylation and transamination of 1-/sup 14/C-branched chain amino and alpha-keto acids were examined in mitochondria isolated from rat heart. Transamination was inhibited by aminooxyacetate, but not by L-cycloserine. At equimolar concentrations of alpha-ketoiso(1-/sup 14/C)valerate (KIV) and isoleucine, transamination was increased by disrupting the mitochondria with detergent which suggests transport may be one factor affecting the rate of transamination. Next, the subcellular distribution of the aminotransferase(s) was determined. Branched chain aminotransferase activity was measured using two concentrations of isoleucine as amino donor and (1-/sup 14/C)KIV as amino acceptor. The data show that branched chain aminotransferase activity is located exclusively in the mitochondria in rat heart. Metabolism of extramitochondrial branched chain alpha-keto acids was examined using 20 microM (1-/sup 14/C)KIV and alpha-ketoiso(1-/sup 14/C)caproate (KIC). There was rapid uptake and oxidation of labeled branched chain alpha-keto acid, and, regardless of the experimental condition, greater than 90% of the labeled keto acid substrate was metabolized during the 20-min incubation. When a branched chain amino acid (200 microM) or glutamate (5 mM) was present, 30-40% of the labeled keto acid was transaminated while the remainder was oxidized. Provision of an alternate amino acceptor in the form of alpha-keto-glutarate (0.5 mM) decreased transamination of the labeled KIV or KIC and increased oxidation. Metabolism of intramitochondrially generated branched chain alpha-keto acids was studied using (1-/sup 14/C)leucine and (1-/sup 14/C)valine. Essentially all of the labeled branched chain alpha-keto acid produced by transamination of (1-/sup 14/C)leucine or (1-/sup 14/C)valine with a low concentration of unlabeled branched chain alpha-keto acid (20 microM) was oxidized.

  4. 40 CFR 721.10024 - 10H-Phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-branched alkyl) derivs. 721.10024 Section 721.10024 Protection of Environment ENVIRONMENTAL PROTECTION... alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 10H-phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs (PMN P-01-771; CAS...

  5. 40 CFR 721.10024 - 10H-Phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-branched alkyl) derivs. 721.10024 Section 721.10024 Protection of Environment ENVIRONMENTAL PROTECTION... alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 10H-phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs (PMN P-01-771; CAS...

  6. 40 CFR 721.10024 - 10H-Phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-branched alkyl) derivs. 721.10024 Section 721.10024 Protection of Environment ENVIRONMENTAL PROTECTION... alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 10H-phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs (PMN P-01-771; CAS...

  7. 40 CFR 721.10024 - 10H-Phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-branched alkyl) derivs. 721.10024 Section 721.10024 Protection of Environment ENVIRONMENTAL PROTECTION... alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 10H-phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs (PMN P-01-771; CAS...

  8. 40 CFR 721.10024 - 10H-Phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-branched alkyl) derivs. 721.10024 Section 721.10024 Protection of Environment ENVIRONMENTAL PROTECTION... alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 10H-phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs (PMN P-01-771; CAS...

  9. Immobilization of Lipases on Alkyl Silane Modified Magnetic Nanoparticles: Effect of Alkyl Chain Length on Enzyme Activity

    PubMed Central

    Wang, Jiqian; Meng, Gang; Tao, Kai; Feng, Min; Zhao, Xiubo; Li, Zhen; Xu, Hai; Xia, Daohong; Lu, Jian R.

    2012-01-01

    Background Biocatalytic processes often require a full recycling of biocatalysts to optimize economic benefits and minimize waste disposal. Immobilization of biocatalysts onto particulate carriers has been widely explored as an option to meet these requirements. However, surface properties often affect the amount of biocatalysts immobilized, their bioactivity and stability, hampering their wide applications. The aim of this work is to explore how immobilization of lipases onto magnetite nanoparticles affects their biocatalytic performance under carefully controlled surface modification. Methodology/Principal Findings Magnetite nanoparticles, prepared through a co-precipitation method, were coated with alkyl silanes of different alkyl chain lengths to modulate their surface hydrophobicity. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through hydrophobic interaction. Enzyme activity was assessed by catalytic hydrolysis of p-nitrophenyl acetate. The activity of immobilized lipases was found to increase with increasing chain length of the alkyl silane. Furthermore, the catalytic activities of lipases immobilized on trimethoxyl octadecyl silane (C18) modified Fe3O4 were a factor of 2 or more than the values reported from other surface immobilized systems. After 7 recycles, the activities of the lipases immobilized on C18 modified nanoparticles retained 65%, indicating significant enhancement of stability as well through hydrophobic interaction. Lipase immobilized magnetic nanoparticles facilitated easy separation and recycling with high activity retaining. Conclusions/Significance The activity of immobilized lipases increased with increasing alkyl chain length of the alkyl trimethoxy silanes used in the surface modification of magnetite nanoparticles. Lipase stability was also improved through hydrophobic interaction. Alkyl silane modified magnetite nanoparticles are thus highly attractive carriers for enzyme immobilization

  10. Unraveling heterogeneous microviscosities of the 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids with different chain lengths.

    PubMed

    Li, Boxuan; Qiu, Meng; Long, Saran; Wang, Xuefei; Guo, Qianjin; Xia, Andong

    2013-10-14

    The rotational dynamics of coumarin 153 (C153) have been investigated in a series of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids with different alkyl chain lengths (alkyl = butyl, pentyl, hexyl, heptyl, octyl) ([Cnmim][PF6], n = 4-8) to examine the alkyl chain length dependent local viscosity of the microenvironment surrounding the probe molecules. The excimer-to-monomer fluorescence emission intensity ratio (IE/IM) of a well-known microviscosity probe, 1,3-bis(1-pyrenyl)propane (BPP), is also employed to study the microviscosity of [Cnmim][PF6] as a complementary measurement. The rotational dynamics of C153 show that at a certain length of the alkyl chain there are incompact and compact domains within [Cnmim][PF6], resulting in fast and slow components of C153 rotational dynamics. The microviscosities in different structural domains of [Cnmim][PF6] with different alkyl chain lengths are investigated by studying the fluorescence anisotropy decay of probe molecules. The obtained average rotation time constants show that with an increase in the length of the alkyl chain, the microviscosity of [Cnmim][PF6] is obviously increased first and then slightly decreased. The steady state fluorescence measurements with the microviscosity probe of BPP further prove that the microviscosity is not increased as much as expected when ionic liquids [Cnmim][PF6] have a relatively long alkyl chain. The different heterogeneous structures of [Cnmim][PF6] with different lengths of the alkyl chain are proposed to interpret the unusual microviscosity behaviors.

  11. γ-Radiolysis of branched chain hydrocarbons: 2,4-dimethylpentane

    NASA Astrophysics Data System (ADS)

    Castello, Gianrico; D'Amato, Giuseppina; Tealdo, Giancarlo

    The γ-radiolysis of liquid 2,4-dimethylpentane was investigated vacuo as a function of total dose in the range 0.5-2.7 × 10 20 eV g -1. Iodine was used as a scavenger to identify the primary radicals, the alkyl iodides so formed being analysed by gas chromatography with ECD. The radiation-chemical yields of rupture of the various C-H and C-C bonds of the molecule were calculated and compared with the corresponding values for similar bonds in other branched-chain alkanes.

  12. 40 CFR 721.10441 - 1,2-Benzenedicarboxylic acid, di-C7-14-branched and linear alkyl esters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-branched and linear alkyl esters. 721.10441 Section 721.10441 Protection of Environment ENVIRONMENTAL...-branched and linear alkyl esters. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1,2-benzenedicarboxylic acid, di-C7-14-branched and linear...

  13. 40 CFR 721.10023 - Benzenamine, N-phenyl-, ar ar′-(C9-rich C88-10-branched alkyl) derivs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-rich C88-10-branched alkyl) derivs. 721.10023 Section 721.10023 Protection of Environment ENVIRONMENTAL...-10-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzenamine, N-phenyl-, ar,ar′-(C9-rich C8-10-branched...

  14. 40 CFR 721.10023 - Benzenamine, N-phenyl-, ar ar′-(C9-rich C88-10-branched alkyl) derivs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-rich C88-10-branched alkyl) derivs. 721.10023 Section 721.10023 Protection of Environment ENVIRONMENTAL...-10-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzenamine, N-phenyl-, ar,ar′-(C9-rich C8-10-branched...

  15. 40 CFR 721.10442 - 1,2-Benzenedicarboxylic acid, di-C6-14-branched and linear alkyl esters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-branched and linear alkyl esters. 721.10442 Section 721.10442 Protection of Environment ENVIRONMENTAL...-branched and linear alkyl esters. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1,2-benzenedicarboxylic acid, di-C6-14-branched and linear...

  16. 40 CFR 721.10023 - Benzenamine, N-phenyl-, ar ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-rich C8-10-branched alkyl) derivs. 721.10023 Section 721.10023 Protection of Environment ENVIRONMENTAL...-10-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzenamine, N-phenyl-, ar,ar′-(C9-rich C8-10-branched...

  17. 40 CFR 721.10023 - Benzenamine, N-phenyl-, ar ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-rich C8-10-branched alkyl) derivs. 721.10023 Section 721.10023 Protection of Environment ENVIRONMENTAL...-10-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzenamine, N-phenyl-, ar,ar′-(C9-rich C8-10-branched...

  18. 40 CFR 721.10023 - Benzenamine, N-phenyl-, ar ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-rich C8-10-branched alkyl) derivs. 721.10023 Section 721.10023 Protection of Environment ENVIRONMENTAL...-10-branched alkyl) derivs. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzenamine, N-phenyl-, ar,ar′-(C9-rich C8-10-branched...

  19. The entry of HCl through soluble surfactants on sulfuric acid: effects of chain branching.

    PubMed

    Burden, Daniel K; Johnson, Alexis M; Krier, James M; Nathanson, Gilbert M

    2014-07-17

    Gas-liquid scattering experiments are used to determine how a soluble, branched surfactant (2-ethylbutanol) controls the entry of gaseous HCl molecules into 60 and 68 wt % D2SO4 at 213 K. Short-chain alcohols spontaneously segregate to the surfaces of these sulfuric acid solutions, which are representative of aerosol droplets in the lower stratosphere. We find that 2-ethylbutanol enhances HCl entry at low surface coverages, most likely because it provides extra interfacial OH groups that aid HCl dissociation. This enhancement disappears at higher coverages as the alkyl chains crowd each other and block access to the acid. The branched alcohol impedes HCl entry more effectively than its unbranched isomer 1-hexanol, implying that the larger 2-ethybutanol footprint on the surface blocks more HCl molecules from reaching the alcohol-acid interface. This behavior contrasts sharply with gas transport through long-chain monolayers, where branching introduces gaps that allow more facile passage. The experiments suggest that short-chain surfactants with extended footprints may impede transport more effectively than their unbranched isomers. PMID:24620717

  20. Nonlinear viscoelastic properties of long-chain randomly branched polybutadiene

    SciTech Connect

    Kasehagen, L.J.; Macosko, C.W.

    1996-12-31

    The presence of long-chain random branching in polymer melts is known to have a large effect on a material`s viscoelastic properties. A hydrosilation reaction between near-monodisperse polybutadiene and a small difunctional crosslinker was used to produce polymer with well characterized random branching for rheological study. Although, previous work has characterized the branching, molecular weight distribution and linear viscoelastic properties of the system, non-linear properties are often of more importance in processing and will be reported on in this work. The shear behavior of a series of polybutadienes of varying branching content were investigated using start-up of steady shear and step shear measurements. Transient uniaxial extensional measurements were also made using a fiber-windup technique on a commercial shear rheometer. Results will be presented by comparison with the linear viscoelastic results and non-linear constitutive equations. Particular emphasis will be placed on changes in the damping function as branching content increases.

  1. Interaction between DNA and trimethyl-ammonium bromides with different alkyl chain lengths.

    PubMed

    Cheng, Chao; Ran, Shi-Yong

    2014-01-01

    The interaction between λ--DNA and cationic surfactants with varying alkyl chain lengths was investigated. By dynamic light scattering method, the trimethyl-ammonium bromides-DNA complex formation was shown to be dependent on the length of the surfactant's alkyl chain. For surfactants with sufficient long alkyl chain (CTAB, TTAB, DTAB), the compacted particles exist with a size of ~60-110 nm at low surfactant concentrations. In contrast, high concentration of surfactants leads to aggregates with increased sizes. Atomic force microscope scanning also supports the above observation. Zeta potential measurements show that the potential of the particles decreases with the increase of surfactant concentration (CTAB, TTAB, DTAB), which contributes much to the coagulation of the particles. For OTAB, the surfactant with the shortest chain in this study, it cannot fully neutralize the charges of DNA molecules; consequently, the complex is looser than other surfactant-DNA structures.

  2. Interaction between DNA and Trimethyl-Ammonium Bromides with Different Alkyl Chain Lengths

    PubMed Central

    Cheng, Chao; Ran, Shi-Yong

    2014-01-01

    The interaction between λ—DNA and cationic surfactants with varying alkyl chain lengths was investigated. By dynamic light scattering method, the trimethyl-ammonium bromides-DNA complex formation was shown to be dependent on the length of the surfactant's alkyl chain. For surfactants with sufficient long alkyl chain (CTAB, TTAB, DTAB), the compacted particles exist with a size of ~60–110 nm at low surfactant concentrations. In contrast, high concentration of surfactants leads to aggregates with increased sizes. Atomic force microscope scanning also supports the above observation. Zeta potential measurements show that the potential of the particles decreases with the increase of surfactant concentration (CTAB, TTAB, DTAB), which contributes much to the coagulation of the particles. For OTAB, the surfactant with the shortest chain in this study, it cannot fully neutralize the charges of DNA molecules; consequently, the complex is looser than other surfactant-DNA structures. PMID:24574926

  3. Dependence of micelle size and shape on detergent alkyl chain length and head group.

    PubMed

    Oliver, Ryan C; Lipfert, Jan; Fox, Daniel A; Lo, Ryan H; Doniach, Sebastian; Columbus, Linda

    2013-01-01

    Micelle-forming detergents provide an amphipathic environment that can mimic lipid bilayers and are important tools for solubilizing membrane proteins for functional and structural investigations in vitro. However, the formation of a soluble protein-detergent complex (PDC) currently relies on empirical screening of detergents, and a stable and functional PDC is often not obtained. To provide a foundation for systematic comparisons between the properties of the detergent micelle and the resulting PDC, a comprehensive set of detergents commonly used for membrane protein studies are systematically investigated. Using small-angle X-ray scattering (SAXS), micelle shapes and sizes are determined for phosphocholines with 10, 12, and 14 alkyl carbons, glucosides with 8, 9, and 10 alkyl carbons, maltosides with 8, 10, and 12 alkyl carbons, and lysophosphatidyl glycerols with 14 and 16 alkyl carbons. The SAXS profiles are well described by two-component ellipsoid models, with an electron rich outer shell corresponding to the detergent head groups and a less electron dense hydrophobic core composed of the alkyl chains. The minor axis of the elliptical micelle core from these models is constrained by the length of the alkyl chain, and increases by 1.2-1.5 Å per carbon addition to the alkyl chain. The major elliptical axis also increases with chain length; however, the ellipticity remains approximately constant for each detergent series. In addition, the aggregation number of these detergents increases by ∼16 monomers per micelle for each alkyl carbon added. The data provide a comprehensive view of the determinants of micelle shape and size and provide a baseline for correlating micelle properties with protein-detergent interactions.

  4. Novel branched-chain fatty acids in certain fish oils.

    PubMed

    Ratnayake, W M; Olsson, B; Ackman, R G

    1989-07-01

    Methyl-branched fatty acids, which are usually minor components (equal or less than 0.1%) in fish oils, were concentrated in the non-urea-complexing fraction along with polyunsaturated fatty acids during the enrichment of omega-3 fatty acids from certain fish oils via the urea complexation process. The methyl-branched fatty acids in the omega-3 polyunsaturated fatty acid concentrates, which were prepared from three fish body oils, were characterized by gas chromatography and gas chromatography/mass spectrometry. Among the major branched-chain fatty acids expected and identified were the known isoprenoid acids--mainly 4,8,12-trimethyltridecanoic, pristanic, and phytanic--and the well-known iso and anteiso structures. Two novel phytol-derived multimethyl-branched fatty acids, 2,2,6,10,14-pentamethylpentadecanoic and 2,3,7,11,15-pentamethylhexadecanoic, were identified in redfish (Sebastes sp.) oil. These two fatty acids were absent in oils from menhaden (Brevoortia tyrannus) and Pacific salmon (mixed, but mostly from sockeye, Oncorhynchus nerka). The major branched-chain fatty acid in the salmon oil, 7-methyl-7-hexadecenoic acid, was also present to a moderate extent in menhaden oil. A novel vicinal dimethyl-branched fatty acid, 7,8-dimethyl-7-hexadecenoic was detected in all of the fish oils examined, but was most important in the salmon oil. Three monomethyl-branched fatty acids, 11-methyltetradecanoic acid, and 11- and 13-methylhexadecanoic, hitherto undescribed in fish lipids, were also detected in salmon, redfish and menhaden oils. PMID:2779367

  5. Impact of the Crystalline Packing Structures on Charge Transport and Recombination via Alkyl Chain Tunability of DPP-Based Small Molecules in Bulk Heterojunction Solar Cells.

    PubMed

    Song, Chang Eun; Kim, Yu Jin; Suranagi, Sanjaykumar R; Kini, Gururaj P; Park, Sangheon; Lee, Sang Kyu; Shin, Won Suk; Moon, Sang-Jin; Kang, In-Nam; Park, Chan Eon; Lee, Jong-Cheol

    2016-05-25

    A series of small compound materials based on benzodithiophene (BDT) and diketopyrrolopyrrole (DPP) with three different alkyl side chains were synthesized and used for organic photovoltaics. These small compounds had different alkyl branches (i.e., 2-ethylhexyl (EH), 2-butyloctyl (BO), and 2-hexyldecyl (HD)) attached to DPP units. Thin films made of these compounds were characterized and their solar cell parameters were measured in order to systematically analyze influences of the different side chains of compounds on the film microstructure, molecular packing, and hence, charge-transport and recombination properties. The relatively shorter side chains in the small molecules enabled more ordered packing structures with higher crystallinities, which resulted in higher carrier mobilities and less recombination factors; the small molecule with the EH branches exhibited the best semiconducting properties with a power conversion efficiency of up to 5.54% in solar cell devices. Our study suggested that tuning the alkyl chain length of semiconducting molecules is a powerful strategy for achieving high performance of organic photovoltaics.

  6. MgO encapsulated mesoporous zeolite for the side chain alkylation of toluene with methanol.

    PubMed

    Jiang, Nanzhe; Jin, Hailian; Jeong, Eun-Young; Park, Sang-Eon

    2010-01-01

    Side chain alkylation of toluene with methanol was studied over mesoporous zeolite supported MgO catalysts. MgO were supported onto the carbon templated mesoporous silicalite-1 by direct synthesis route under microwave conditions. This direct synthesis route yields the majority of MgO highly dispersed into the mesopores of the silicalite-1 crystals. The vapor phase alkylation of toluene with methanol was performed over these catalysts under vapor phase conditions at atmospheric pressure. Mesoporous silicalite-1 supported MgO catalysts gave improved yields towards side chain alkylated products compared to the bulk MgO. The higher activity exhibited by 5% MgO supported on mesoporous silicalite compared to the one with 1% MgO can be attributed to the large number of weak basic sites observed from the CO2 TPD.

  7. Additional chain-branching pathways in the low-temperature oxidation of branched alkanes

    DOE PAGES

    Wang, Zhandong; Zhang, Lidong; Moshammer, Kai; Popolan-Vaida, Denisia M.; Shankar, Vijai Shankar Bhavani; Lucassen, Arnas; Hemken, Christian; Taatjes, Craig A.; Leone, Stephen R.; Kohse-Hoinghaus, Katharina; et al

    2015-12-31

    Chain-branching reactions represent a general motif in chemistry, encountered in atmospheric chemistry, combustion, polymerization, and photochemistry; the nature and amount of radicals generated by chain-branching are decisive for the reaction progress, its energy signature, and the time towards its completion. In this study, experimental evidence for two new types of chain-branching reactions is presented, based upon detection of highly oxidized multifunctional molecules (HOM) formed during the gas-phase low-temperature oxidation of a branched alkane under conditions relevant to combustion. The oxidation of 2,5-dimethylhexane (DMH) in a jet-stirred reactor (JSR) was studied using synchrotron vacuum ultra-violet photoionization molecular beam mass spectrometry (SVUV-PI-MBMS).more » Specifically, species with four and five oxygen atoms were probed, having molecular formulas of C8H14O4 (e.g., diketo-hydroperoxide/keto-hydroperoxy cyclic ether) and C8H16O5 (e.g., keto-dihydroperoxide/dihydroperoxy cyclic ether), respectively. The formation of C8H16O5 species involves alternative isomerization of OOQOOH radicals via intramolecular H-atom migration, followed by third O2 addition, intramolecular isomerization, and OH release; C8H14O4 species are proposed to result from subsequent reactions of C8H16O5 species. The mechanistic pathways involving these species are related to those proposed as a source of low-volatility highly oxygenated species in Earth's troposphere. At the higher temperatures relevant to auto-ignition, they can result in a net increase of hydroxyl radical production, so these are additional radical chain-branching pathways for ignition. Furthermore, the results presented herein extend the conceptual basis of reaction mechanisms used to predict the reaction behavior of ignition, and have implications on atmospheric gas-phase chemistry and the oxidative stability of organic substances.« less

  8. Conformation-specific spectroscopy of alkyl benzyl radicals: Effects of a radical center on the CH stretch infrared spectrum of an alkyl chain

    NASA Astrophysics Data System (ADS)

    Korn, Joseph A.; Tabor, Daniel P.; Sibert, Edwin L.; Zwier, Timothy S.

    2016-09-01

    An important initial step in the combustion of gasoline and diesel fuels is the abstraction of hydrogen from alkylbenzenes to form resonance-stabilized alkyl benzyl radicals. This work uses, for the first time, double resonance spectroscopy methods to explore the conformation-specific vibronic and infrared spectroscopy of the α-ethylbenzyl (αEtBz) and α-propylbenzyl (αPrBz) radicals. Local mode Hamiltonian modeling enables assignment of the alkyl CH stretch IR spectra, accounting for Fermi resonance that complicates aliphatic alkyl CH stretch IR spectroscopy. The ground state conformational preferences of the ethyl and propyl chains are changed from those in the alkylbenzenes themselves, with global minima occurring for an in-plane orientation of the alkyl chain (trans) about its first dihedral angle (ϕf123, numbers are alkyl C atoms. C1 is CH radical site). This in-plane structure is the only observed conformer for the α-EtBz radical, while two conformers, tt and tg' share this orientation at the first dihedral, but differ in the second (ϕ1234) for the αPrBz radical. The in-plane orientation lowers the local site frequencies of the CH2 group stretches immediately adjacent to the benzylic radical site by about 50 cm-1 relative to those in pure alkyl chains or alkylbenzenes. This effect of the radical site is localized on the first CH2 group, with little effect on subsequent members of the alkyl chain. In the D1 excited electronic state, an out-of-plane orientation is preferred for the alkyl chains, leading to torsional mode Franck-Condon activity in the D0-D1 spectra that is both conformer-specific and diagnostic of the conformational change.

  9. Diacyltransferase Activity and Chain Length Specificity of Mycobacterium tuberculosis PapA5 in the Synthesis of Alkyl β-Diol Lipids

    SciTech Connect

    Touchette, Megan H.; Bommineni, Gopal R.; Delle Bovi, Richard J.; Gadbery, John; Nicora, Carrie D.; Shukla, Anil K.; Kyle, Jennifer E.; Metz, Thomas O.; Martin, Dwight W.; Sampson, Nicole S.; Miller, W. T.; Tonge, Peter J.; Seeliger, Jessica C.

    2015-09-08

    Although classified as Gram-positive bacteria, Corynebacterineae possess an asymmetric outer membrane that imparts structural and thereby physiological similarity to more distantly related Gram-negative bacteria. Like lipopolysaccharide in Gram-negative bacteria, lipids in the outer membrane of Corynebacterineae have been associated with the virulence of pathogenic species such as Mycobacterium tuberculosis (Mtb). For example, Mtb strains that lack long, branched-chain alkyl esters known as dimycocerosates (DIMs) are significantly attenuated in model infections. The resultant interest in the biosynthetic pathway of these unusual virulence factors has led to the elucidation of many of the steps leading to the final esterification of the alkyl beta-diol, phthiocerol, with branched-chain fatty acids know as mycocerosates. PapA5 is an acyltransferase implicated in these final reactions. We here show that PapA5 is indeed the terminal enzyme in DIM biosynthesis by demonstrating its dual esterification activity and chain-length preference using synthetic alkyl beta-diol substrate analogues. Applying these analogues to a series of PapA5 mutants, we also revise a model for the substrate binding within PapA5. Finally, we demonstrate that the Mtb Ser/Thr kinase PknB modifies PapA5 on three Thr residues, including two (T196, T198) located on an unresolved loop. These results clarify the DIM biosynthetic pathway and suggest possible mechanisms by which DIM biosynthesis may be regulated by the post-translational modification of PapA5.

  10. Spectroscopic study on interaction between three cationic surfactants with different alkyl chain lengths and DNA.

    PubMed

    Guo, Lili; Zhang, Zhaohong; Qiao, Heng; Liu, Miao; Shen, Manli; Yuan, Tianxin; Chen, Jing; Dionysiou, Dionysios D

    2015-01-01

    In this study, the interaction between cationic surfactants with different alkyl chain lengths, such as hexyltrimethyl ammonium bromide (HTAB), dodecyltrimethyl ammonium bromide (DTAB) and cetyltrimethyl ammonium bromide (CTAB), and DNA was investigated by UV-vis spectroscopy, fluorescence spectroscopy and viscosity techniques. The results showed that these three cationic surfactants with different hydrocarbon chain lengths could all interact with DNA. Their binding modes were estimated and their interaction strength was compared. In addition, the effects of the surfactant, NaCl and phosphate ion concentrations on the interaction were reviewed. It is wished that this work would provide some valuable references to investigate the influence of cationic surfactants with different alkyl chain lengths on DNA.

  11. Cation alkyl side chain length and symmetry effects on the surface tension of ionic liquids.

    PubMed

    Almeida, Hugo F D; Freire, Mara G; Fernandes, Ana M; Lopes-da-Silva, José A; Morgado, Pedro; Shimizu, Karina; Filipe, Eduardo J M; Lopes, José N Canongia; Santos, Luís M N B F; Coutinho, João A P

    2014-06-10

    Aiming at providing a comprehensive study of the influence of the cation symmetry and alkyl side chain length on the surface tension and surface organization of ionic liquids (ILs), this work addresses the experimental measurements of the surface tension of two extended series of ILs, namely R,R'-dialkylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C(n)C(n)im][NTf2]) and R-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C(n)C(1)im][NTf2]), and their dependence with temperature (from 298 to 343 K). For both series of ILs the surface tension decreases with an increase in the cation side alkyl chain length up to aliphatic chains no longer than hexyl, here labeled as critical alkyl chain length (CACL). For ILs with aliphatic moieties longer than CACL the surface tension displays an almost constant value up to [C12C12im][NTf2] or [C16C1im][NTf2]. These constant values further converge to the surface tension of long chain n-alkanes, indicating that, for sufficiently long alkyl side chains, the surface ordering is strongly dominated by the aliphatic tails present in the IL. The enthalpies and entropies of surface were also derived and the critical temperatures were estimated from the experimental data. The trend of the derived thermodynamic properties highlights the effect of the structural organization of the IL at the surface with visible trend shifts occurring at a well-defined CACL in both symmetric and asymmetric series of ILs. Finally, the structure of a long-alkyl side chain IL at the vacuum-liquid interface was also explored using Molecular Dynamics simulations. In general, it was found that for the symmetric series of ILs, at the outermost polar layers, more cations point one of their aliphatic tails outward and the other inward, relative to the surface, than cations pointing both tails outward. The number of the former, while being the preferred conformation, exceeds the latter by around 75%.

  12. Photoinitiated electron transfer to selected physisorbed alkyl bromides: The effects of alkyl chain length on dissociation cross sections

    SciTech Connect

    Khan, K.A.; Camillone, N. III; Osgood, R.M. Jr.

    1999-06-01

    We report the results of measurements of the cross section as a function of wavelength (351, 248, and 193 nm) for photoinitiated dissociative electron attachment to three normal alkyl bromides [CH{sub 3}(CH{sub 2}){sub n{minus}1}Br, n=1, 2, and 3] physisorbed on GaAs(110). Upon UV exposure, the molecules undergo C{endash}Br bond cleavage due to a substrate-mediated electron-transfer process. The cross sections for all three molecules increase monotonically with decreasing wavelength. Our results suggest a {approximately}1 eV higher threshold for dissociation of ethyl and propyl bromide than for methyl bromide. A simple model of the electron-transfer process is employed to estimate the peak per-electron cross section for dissociative attachment in the monolayer. We find that the cross sections for the physisorbed molecules are approximately five times smaller than those for gas-phase molecules, due to a reduction in the lifetime of the molecular anion in the vicinity of the surface. In addition, we also find an increase in cross section with chain length very similar to that observed in the gas phase; the gas-phase behavior has been explained by an increase in the anion lifetime with chain length. Our results suggest that while quenching of the molecular anion at the surface is important, it does not eliminate the progression of anion lifetime with chain length. {copyright} {ital 1999 American Institute of Physics.}

  13. Effect of Alkyl Chain Length and Unsaturation of the Phospholipid on the Physicochemical Properties of Lipid Nanoparticles.

    PubMed

    Funakoshi, Yuka; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

    2015-01-01

    Previously, we developed lipid nanoparticles (LNs) containing poorly water-soluble drugs using two types of phospholipids, a neutral phospholipid (hydrogenated soybean phosphatidylcholine) and a negatively-charged phospholipid (dipalmitoylphosphatidylglycerol), with mean particle sizes of less than 100 nm. Here, we studied the effects of alkyl chain length and unsaturation of neutral and negatively-charged phospholipids on the physicochemical properties of LNs. Three neutral phospholipids, dimyristoylphosphatidylcholine, dipalmitoylphosphatidylcholine and distearoylphosphatidylcholine, having different alkyl chain lengths, were compared. The mean particle size of the LNs increased with the alkyl chain length, while the concentration of the drug entrapped in the LNs decreased. The particle size of all of the LNs could be maintained at less than 100 nm for 1 month in cool and dark conditions, with the LNs with longer alkyl chain lipids showing greater stability. In the unsaturated phospholipids, the double bond in the alkyl chain of dioleoylphosphatidylcholine and dierucoylphosphatidylcholine did not affect the physicochemical properties of the LNs. The negatively-charged phospholipids dipalmitoylphosphatidylglycerol and distearoylphosphatidylglycerol were also compared; LNs with longer alkyl chain lipids had larger particle sizes and lower drug concentrations, similar to the results for neutral phospholipids. We concluded that although some changes in physicochemical properties were observed among LNs with different phospholipid alkyl chain lengths, this methodology was general. LNs with suitable physicochemical properties could be prepared irrespective of the type of phospholipids used.

  14. Influence of the alkyl chain length on the fluorescence properties of N-alkyl-2,3-naphthalimides included in β-cyclodextrin

    NASA Astrophysics Data System (ADS)

    Vieira Ferreira, Luis Filipe; Lemos, Maria João; Wintgens, Véronique; Netto-Ferreira, José Carlos

    1999-06-01

    Absorption spectra of N-alkyl-2,3-naphthalimides (1, R=CH3; 2,: R=n-C6H13; 3, R=n-C12H25; 4, R=n-C18H37) show absorption maximum independent of the alkyl chain length but dependent on the nature of the solvent. In the polar aprotic solvent acetonitrile N-alkyl-2,3-naphthalimides 1-4 exhibit a vibrationally resolved fluorescence emission, while in polar protic solvents (methanol or water) their fluorescence is broad and shows a bathochromic shift when compared to the one in acetonitrile. This behaviour is in agreement with previously reported data on N-methyl-2,3-naphthalimide. By the addition of aqueous solutions of β-cyclodextrin (β-CD) (concentration ranging from 1×10-3 to 1×10-2 M) to an aqueous solution of the probe, a hypsochromic shift and a strong increase of the fluorescence intensity were observed for short, i.e. 1, and long alkyl chains, i.e. 2-4. From these data we can conclude that an inclusion complex between 1-4 and β-CD is formed. The inclusion geometry for these complexes is dramatically affected by the alkyl chain length. Thus, for the short chain N-alkyl-2,3-naphthalimide, 1, a broad emission is revealed, whereas for long chains, 2-4, a vibrationally structured emission was observed. This indicates a tighter geometry for the latter case, which is a consequence of the inclusion of both the naphthalimide moiety and the alkyl group into the β-CD cavity.

  15. Syn-Selective Synthesis of β-Branched α-Amino Acids by Alkylation of Glycine-Derived Imines with Secondary Sulfonates.

    PubMed

    Lou, Sha; McKenna, Grace M; Tymonko, Steven A; Ramirez, Antonio; Benkovics, Tamas; Conlon, David A; González-Bobes, Francisco

    2015-10-16

    A syn-selective synthesis of β-branched α-amino acids has been developed based on the alkylation of glycine imine esters with secondary sulfonates. The potassium counterion for the enolate, the solvent, and the leaving group on the electrophile were key levers to maximize the diasteroselectivity of the alkylation. The optimized conditions enabled a straightforward preparation of a number of β-branched α-amino acids that can be challenging to obtain.

  16. Additional chain-branching pathways in the low-temperature oxidation of branched alkanes

    SciTech Connect

    Wang, Zhandong; Zhang, Lidong; Moshammer, Kai; Popolan-Vaida, Denisia M.; Shankar, Vijai Shankar Bhavani; Lucassen, Arnas; Hemken, Christian; Taatjes, Craig A.; Leone, Stephen R.; Kohse-Hoinghaus, Katharina; Hansen, Nils; Dagaut, Philippe; Sarathy, S. Mani

    2015-12-31

    Chain-branching reactions represent a general motif in chemistry, encountered in atmospheric chemistry, combustion, polymerization, and photochemistry; the nature and amount of radicals generated by chain-branching are decisive for the reaction progress, its energy signature, and the time towards its completion. In this study, experimental evidence for two new types of chain-branching reactions is presented, based upon detection of highly oxidized multifunctional molecules (HOM) formed during the gas-phase low-temperature oxidation of a branched alkane under conditions relevant to combustion. The oxidation of 2,5-dimethylhexane (DMH) in a jet-stirred reactor (JSR) was studied using synchrotron vacuum ultra-violet photoionization molecular beam mass spectrometry (SVUV-PI-MBMS). Specifically, species with four and five oxygen atoms were probed, having molecular formulas of C8H14O4 (e.g., diketo-hydroperoxide/keto-hydroperoxy cyclic ether) and C8H16O5 (e.g., keto-dihydroperoxide/dihydroperoxy cyclic ether), respectively. The formation of C8H16O5 species involves alternative isomerization of OOQOOH radicals via intramolecular H-atom migration, followed by third O2 addition, intramolecular isomerization, and OH release; C8H14O4 species are proposed to result from subsequent reactions of C8H16O5 species. The mechanistic pathways involving these species are related to those proposed as a source of low-volatility highly oxygenated species in Earth's troposphere. At the higher temperatures relevant to auto-ignition, they can result in a net increase of hydroxyl radical production, so these are additional radical chain-branching pathways for ignition. Furthermore, the results presented herein extend the conceptual basis of reaction mechanisms used to predict the reaction behavior of ignition, and have

  17. Two-dimensional porous molecular networks of dehydrobenzo[12]annulene derivatives via alkyl chain interdigitation.

    PubMed

    Tahara, Kazukuni; Furukawa, Shuhei; Uji-i, Hiroshi; Uchino, Tsutomu; Ichikawa, Tomoyuki; Zhang, Jian; Mamdouh, Wael; Sonoda, Motohiro; De Schryver, Frans C; De Feyter, Steven; Tobe, Yoshito

    2006-12-27

    The self-assembly of a series of hexadehydrotribenzo[12]annulene (DBA) derivatives has been scrutinized by scanning tunneling microscopy (STM) at the liquid-solid interface. First, the influence of core symmetry on the network structure was investigated by comparing the two-dimensional (2D) ordering of rhombic bisDBA 1a and triangular DBA 2a (Figure 1). BisDBA 1a forms a Kagomé network upon physisorption from 1,2,4-trichlorobenzene (TCB) onto highly oriented pyrolytic graphite (HOPG). Under similar experimental conditions, DBA 2a shows the formation of a honeycomb network. The core symmetry and location of alkyl substituents determine the network structure. The most remarkable feature of the DBA networks is the interdigitation of the nonpolar alkyl chains: they connect the pi-conjugated cores and direct their orientation. As a result, 2D open networks with voids are formed. Second, the effect of alkyl chain length on the structure of DBA patterns was investigated. Upon increasing the length of the alkyl chains (DBAs 3c-e) a transition from honeycomb networks to linear networks was observed in TCB, an observation attributed to stronger molecule-substrate interactions. Third, the effect of solvent on the structure of the nonpolar DBA networks was investigated in four different solvents: TCB as a polar aromatic solvent, 1-phenyloctane as a solvent having both aromatic and aliphatic moieties, n-tetradecane as an aliphatic solvent, and octanoic acid as a polar alkylated solvent. The solvent dramatically changes the structure of the DBA networks. The solvent effects are discussed in terms of factors that influence the mobility of molecules at the liquid-solid interface such as solvation.

  18. Effects of alkyl chain length and solvents on thermodynamic dissociation constants of the ionic liquids with one carboxyl group in the alkyl chain of imidazolium cations.

    PubMed

    Chen, Yuehua; Wang, Huiyong; Wang, Jianji

    2014-05-01

    Thermodynamic dissociation constants of the Brønsted acidic ionic liquids (ILs) are important for their catalytic and separation applications. In this work, a series of imidazolium bromides with one carboxylic acid substitute group in their alkyl chain ([{(CH2)nCOOH}mim]Br, n = 1,3,5,7) have been synthesized, and their dissociation constants (pKa) at different ionic strengths have been determined in aqueous and aqueous organic solvents at 0.1 mole fraction (x) of ethanol, glycol, iso-propanol, and dimethyl sulfoxide by potentiometric titrations at 298.2 K. The standard thermodynamic dissociation constants (pKa(T)) of the ILs in these solvents were calculated from the extended Debye-Hückel equation. It was found that the pKa values increased with the increase of ionic strength of the media and of the addition of organic solvent in water. The pKa(T) values also increased with the increase of the alkyl chain length of cations of the ILs. In addition, the effect of solvent nature on pKa(T) values is interpreted from solvation of the dissociation components and their Gibbs energy of transfer from water to aqueous organic solutions. PMID:24720707

  19. Effects of alkyl chain length and solvents on thermodynamic dissociation constants of the ionic liquids with one carboxyl group in the alkyl chain of imidazolium cations.

    PubMed

    Chen, Yuehua; Wang, Huiyong; Wang, Jianji

    2014-05-01

    Thermodynamic dissociation constants of the Brønsted acidic ionic liquids (ILs) are important for their catalytic and separation applications. In this work, a series of imidazolium bromides with one carboxylic acid substitute group in their alkyl chain ([{(CH2)nCOOH}mim]Br, n = 1,3,5,7) have been synthesized, and their dissociation constants (pKa) at different ionic strengths have been determined in aqueous and aqueous organic solvents at 0.1 mole fraction (x) of ethanol, glycol, iso-propanol, and dimethyl sulfoxide by potentiometric titrations at 298.2 K. The standard thermodynamic dissociation constants (pKa(T)) of the ILs in these solvents were calculated from the extended Debye-Hückel equation. It was found that the pKa values increased with the increase of ionic strength of the media and of the addition of organic solvent in water. The pKa(T) values also increased with the increase of the alkyl chain length of cations of the ILs. In addition, the effect of solvent nature on pKa(T) values is interpreted from solvation of the dissociation components and their Gibbs energy of transfer from water to aqueous organic solutions.

  20. Temperature Induced Surface Rearrangement of Alkyl Side Chain Comb Polymers at the Polymer/Air Interface

    NASA Astrophysics Data System (ADS)

    Gautam, Keshav S.; Dhinojwala, Ali

    2001-04-01

    Monitoring the structural changes of comb polymer surfaces as a function temperature is of practical importance in order to understand the molecular rearrangement and their influence on surface properties. Sum Frequency Generation (SFG) has been employed to resolve the structural changes of alkyl side chains in these comb polymers at a molecular level. The SFG response of these side chains as a function of chain length and bulk transition temperature show strong contributions from the methyl vibrations when the side chains are in the ordered crystalline state. In the melt state, the SFG spectra show peaks corresponding to methylene vibrations. The presence of methylene peaks indicate gauche defects at the surface. The range of this order-disorder transition is shown to be much broader for polymers when compared to the low molecular weight side chain alcohols.

  1. Thermal annealing: a facile way of conferring responsivity to inert alkyl-chain-passivated nanoparticle arrays.

    PubMed

    Zhou, Jun; Song, Guoshuai; Li, Yan; Song, Youxin; Chen, Bin; Zhang, Xuemin; Wang, Tieqiang; Fu, Yu; Li, Fei

    2014-11-01

    This work demonstrates a facile post-treatment strategy, vacuum thermal annealing, to fabricate a dodecanethiol-passivated gold nanoparticle (Au NP) array with organic solvent sensitivity. Through investigating the structure change of the Au NP array, it was found that the interparticle distance decreased during vacuum heat treatment, which meant a closer arrangement of the particles and a more dense packing of the dodecanethiol ligands in the interparticle region. The condensation would increase the interaction of the alkyl chain and enhance their interdigitation. Furthermore, on the basis of the stretching of the alkyl chains in organic solvents, the thermally treated Au NP array showed a good response to organic solvent or vapor by using the interdigitated dodecanethiol network as its responsive unit. The alkyl chains stretch to different extents in different organic solvents, leading to differences in interparticle distance, which provided a distinct blue shift of maximum wavelength upon exposure to various organic solvents or vapors. All of these results indicated that thermal annealing was an efficient way to confer responsivity to inert Au NP arrays. Together with the cost-effectiveness of such NP arrays, this study has potential in the development of economical sensors for medical diagnostics, food safety screening, and environmental pollution monitoring.

  2. Thermodynamic Interactions between Polystyrene and Long-Chain Poly(n-Alkyl Acrylates) Derived from Plant Oils.

    PubMed

    Wang, Shu; Robertson, Megan L

    2015-06-10

    Vegetable oils and their fatty acids are promising sources for the derivation of polymers. Long-chain poly(n-alkyl acrylates) and poly(n-alkyl methacrylates) are readily derived from fatty acids through conversion of the carboxylic acid end-group to an acrylate or methacrylate group. The resulting polymers contain long alkyl side-chains with around 10-22 carbon atoms. Regardless of the monomer source, the presence of alkyl side-chains in poly(n-alkyl acrylates) and poly(n-alkyl methacrylates) provides a convenient mechanism for tuning their physical properties. The development of structured multicomponent materials, including block copolymers and blends, containing poly(n-alkyl acrylates) and poly(n-alkyl methacrylates) requires knowledge of the thermodynamic interactions governing their self-assembly, typically described by the Flory-Huggins interaction parameter χ. We have investigated the χ parameter between polystyrene and long-chain poly(n-alkyl acrylate) homopolymers and copolymers: specifically we have included poly(stearyl acrylate), poly(lauryl acrylate), and their random copolymers. Lauryl and stearyl acrylate were chosen as model alkyl acrylates derived from vegetable oils and have alkyl side-chain lengths of 12 and 18 carbon atoms, respectively. Polystyrene is included in this study as a model petroleum-sourced polymer, which has wide applicability in commercially relevant multicomponent polymeric materials. Two independent methods were employed to measure the χ parameter: cloud point measurements on binary blends and characterization of the order-disorder transition of triblock copolymers, which were in relatively good agreement with one another. The χ parameter was found to be independent of the alkyl side-chain length (n) for large values of n (i.e., n > 10). This behavior is in stark contrast to the n-dependence of the χ parameter predicted from solubility parameter theory. Our study complements prior work investigating the interactions between

  3. Ultrasonic Relaxation Study of 1-Alkyl-3-methylimidazolium-Based Room-Temperature Ionic Liquids: Probing the Role of Alkyl Chain Length in the Cation.

    PubMed

    Zorębski, Michał; Zorębski, Edward; Dzida, Marzena; Skowronek, Justyna; Jężak, Sylwia; Goodrich, Peter; Jacquemin, Johan

    2016-04-14

    Ultrasound absorption spectra of four 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides were determined as a function of the alkyl chain length on the cation from 1-propyl to 1-hexyl from 293.15 to 323.15 K at ambient pressure. Herein, the ultrasound absorption measurements were carried out using a standard pulse technique within a frequency range from 10 to 300 MHz. Additionally, the speed of sound, density, and viscosity have been measured. The presence of strong dissipative processes during the ultrasound wave propagation was found experimentally, i.e., relaxation processes in the megahertz range were observed for all compounds over the whole temperature range. The relaxation spectra (both relaxation amplitude and relaxation frequency) were shown to be dependent on the alkyl side chain length of the 1-alkyl-3-methylimidazolium ring. In most cases, a single-Debye model described the absorption spectra very well. However, a comparison of the determined spectra with the spectra of a few other imidazolium-based ionic liquids reported in the literature (in part recalculated in this work) shows that the complexity of the spectra increases rapidly with the elongation of the alkyl chain length on the cation. This complexity indicates that both the volume viscosity and the shear viscosity are involved in relaxation processes even in relatively low frequency ranges. As a consequence, the sound velocity dispersion is present at relatively low megahertz frequencies.

  4. Ultrasonic Relaxation Study of 1-Alkyl-3-methylimidazolium-Based Room-Temperature Ionic Liquids: Probing the Role of Alkyl Chain Length in the Cation.

    PubMed

    Zorębski, Michał; Zorębski, Edward; Dzida, Marzena; Skowronek, Justyna; Jężak, Sylwia; Goodrich, Peter; Jacquemin, Johan

    2016-04-14

    Ultrasound absorption spectra of four 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides were determined as a function of the alkyl chain length on the cation from 1-propyl to 1-hexyl from 293.15 to 323.15 K at ambient pressure. Herein, the ultrasound absorption measurements were carried out using a standard pulse technique within a frequency range from 10 to 300 MHz. Additionally, the speed of sound, density, and viscosity have been measured. The presence of strong dissipative processes during the ultrasound wave propagation was found experimentally, i.e., relaxation processes in the megahertz range were observed for all compounds over the whole temperature range. The relaxation spectra (both relaxation amplitude and relaxation frequency) were shown to be dependent on the alkyl side chain length of the 1-alkyl-3-methylimidazolium ring. In most cases, a single-Debye model described the absorption spectra very well. However, a comparison of the determined spectra with the spectra of a few other imidazolium-based ionic liquids reported in the literature (in part recalculated in this work) shows that the complexity of the spectra increases rapidly with the elongation of the alkyl chain length on the cation. This complexity indicates that both the volume viscosity and the shear viscosity are involved in relaxation processes even in relatively low frequency ranges. As a consequence, the sound velocity dispersion is present at relatively low megahertz frequencies. PMID:26982480

  5. Effect of alkyl chain length on the rotational diffusion of nonpolar and ionic solutes in 1-alkyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imides.

    PubMed

    Gangamallaiah, V; Dutt, G B

    2013-10-10

    Rotational diffusion of a nonpolar solute 9-phenylanthracene (9-PA) and a cationic solute rhodamine 110 (R110) has been examined in a series of 1-alkyl-3-methylimidazolium (alkyl = octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl) bis(trifluoromethylsulfonyl)imides to understand the influence of alkyl chain length on solute rotation. In this study, reorientation times (τr) have been measured as a function of viscosity (η) by varying the temperature (T) of the solvents. These results have been analyzed using the Stokes-Einstein-Debye (SED) hydrodynamic theory along with the ones obtained for the same solutes in 1-alkyl-3-methylimidazolium (alkyl = methyl, ethyl, propyl, butyl, and hexyl) bis(trifluoromethylsulfonyl)imides (Gangamallaiah and Dutt, J. Phys. Chem. B 2012, 116, 12819-12825). It has been noticed that the data for 9-PA and R110 follows the relation τr = A(η/T)(n) with A being the ratio of hydrodynamic volume of the solute to the Boltzmann constant and n = 1 as envisaged by the SED theory. However, upon increasing the alkyl chain length from methyl to octadecyl significant deviations from the SED theory have been observed especially from the octyl derivative onward. From methyl to octadecyl derivatives, the value of A decreases by a factor of 3 for both the solutes and n by a factor of 1.4 and 1.6 for 9-PA and R110, respectively. These observations have been rationalized by taking into consideration the organized structure of the ionic liquids, whose influence appears to be pronounced when the number of carbon atoms in the alkyl chain attached to the imidazolium cation exceeds eight.

  6. Novel Alkylsulfatases Required for Biodegradation of the Branched Primary Alkyl Sulfate Surfactant 2-Butyloctyl Sulfate

    PubMed Central

    Ellis, Andrew J.; Hales, Stephen G.; Ur-Rehman, Naheed G. A.; White, Graham F.

    2002-01-01

    Recent reports show that contrary to common perception, branched alkyl sulfate surfactants are readily biodegradable in standard biodegradability tests. We report here the isolation of bacteria capable of biodegrading 2-butyloctyl sulfate and the identification of novel enzymes that initiate the process. Enrichment culturing from activated sewage sludge yielded several strains capable of growth on 2-butyloctyl sulfate. Of these, two were selected for further study and identified as members of the genus Pseudomonas. Strain AE-A was able to utilize either sodium dodecyl sulfate (SDS) or 2-butyloctyl sulfate as a carbon and energy source for growth, but strain AE-D utilized only the latter. Depending on growth conditions, strain AE-A produced up to three alkylsulfatases, as shown by polyacrylamide gel electrophoresis zymography. Growth on either SDS or 2-butyloctyl sulfate or in nutrient broth produced an apparently constitutive, nonspecific primary alkylsulfatase, AP1, weakly active on SDS and on 2-butyloctyl sulfate. Growth on 2-butyloctyl sulfate produced a second enzyme, AP2, active on 2-butyloctyl sulfate but not on SDS, and growth on SDS produced a third enzyme, AP3, active on SDS but not on 2-butyloctyl sulfate. In contrast, strain AE-D, when grown on 2-butyloctyl sulfate (no growth on SDS), produced a single enzyme, DP1, active on 2-butyloctyl sulfate but not on SDS. DP1 was not produced in broth cultures. DP1 was induced when residual 2-butyloctyl sulfate was present in the growth medium, but the enzyme disappeared when the substrate was exhausted. Gas chromatographic analysis of products of incubating 2-butyloctyl sulfate with DP1 in gels revealed the formation of 2-butyloctanol, showing the enzyme to be a true sulfatase. In contrast, Pseudomonas sp. strain C12B, well known for its ability to degrade linear SDS, was unable to grow on 2-butyloctyl sulfate, and its alkylsulfatases responsible for initiating the degradation of SDS by releasing the parent

  7. Characterization of alkylphenol degradation gene cluster in Pseudomonas putida MT4 and evidence of oxidation of alkylphenols and alkylcatechols with medium-length alkyl chain.

    PubMed

    Takeo, Masahiro; Prabu, Subbuswamy K; Kitamura, Chitoshi; Hirai, Makoto; Takahashi, Hana; Kato, Dai-Ichiro; Negoro, Seiji

    2006-10-01

    Alkylphenols (APs) are ubiquitous contaminants in aquatic environments and have endocrine disrupting and toxic effects on aquatic organisms. To investigate biodegradation mechanisms of APs, an AP degradation gene cluster was cloned from a butylphenol (BP)-degrading bacterium, Pseudomonas putida MT4. The gene cluster consisted of 13 genes named bupBA1A2A3A4A5A6CEHIFG. From the nucleotide sequences, bupA1A2A3A4A5A6 were predicted to encode a multicomponent phenol hydroxylase (PH), whereas bupBCEHIFG were expected to encode meta-cleavage pathway enzymes. A partial sequence of a putative NtrC-type regulatory gene, bupR, was also found upstream of the gene bupB. This result indicates that APs can be initially oxidized into alkylcatechols (ACs), followed by the meta-cleavage of the aromatic rings. To confirm this pathway, AP degradation tests were carried out using the recombinant P. putida KT2440 harboring the PH genes (bupA1A2A3A4A5A6). The recombinant strain oxidized 4-n-APs with an alkyl chain of up to C7 (< or = C7) efficiently and also several BPs including those with an alkyl chain with some degree of branching. Therefore, it was found that PH had a broad substrate specificity for APs with a medium-length alkyl chain (C3-C7). Moreover, the cell extract of a recombinant Escherichia coli harboring bupB (a catechol 2,3-dioxygenase gene) converted 4-n-ACs with an alkyl chain of < or = C9 into yellow meta-cleavage products with a maximum absorbance at 379 nm, indicating that the second step enzyme in this pathway is also responsible for the degradation of ACs with a medium-length alkyl chain. These results suggest that MT4 is a very useful strain in the biodegradation of a wide range of APs with a medium-length alkyl chain, which known nonylphenol-degrading Sphingomonas strains have never degraded. PMID:17116584

  8. Diastereoselective synthesis of new O-alkylated and C-branched inositols and their corresponding fluoro analogues

    PubMed Central

    Chrétien, Françoise; Chapleur, Yves

    2016-01-01

    Summary Efficient routes were developed for the diastereoselective synthesis of new O-alkylated and C-branched inositols and their corresponding fluoro analogues. The key steps of the synthesis were the easy accessibility of different types of arms in term of configuration (myo and scyllo), the linking method and length, which could modulate the biological properties. These inositol derivatives, bearing an arm terminated either with a hydroxy group or a fluorine atom, could be interesting candidates for diastereoisomeric intermediates and biological evaluations, especially for PET imaging experiments. PMID:26977196

  9. Structure and entanglements in short chain branched polyolefin melts

    NASA Astrophysics Data System (ADS)

    Moorthi, K.; Kamio, K.; Ramos, J.; Theodorou, D. N.

    2013-02-01

    Atomistic models of short chain branched (SCB) polyethylene melts containing up to 20-40 mol% of comonomer (1-butene, 1-hexene, 1-octene or 1-decene) have been equilibrated at 450 K using a connectivity altering Monte Carlo method, and analyzed for topological constraints using Z1 and CReTA codes. The calculated tube diameters, , of SCB melts are found to scale with the backbone weight fraction, φ, as ˜φ-0.46, close to the scaling predicted by the binary contact model, ˜φ-0.5 and in disagreement with the packing model prediction ˜φ-1.27. Similar scaling relationships are observed experimentally for polymer solutions, and reproduced by the present methods.

  10. Decreased consumption of branched chain amino acids improves metabolic health

    PubMed Central

    Arriola Apelo, Sebastian I.; Neuman, Joshua C.; Kasza, Ildiko; Schmidt, Brian A.; Cava, Edda; Spelta, Francesco; Tosti, Valeria; Syed, Faizan A.; Baar, Emma L.; Veronese, Nicola; Cottrell, Sara E.; Fenske, Rachel J.; Bertozzi, Beatrice; Brar, Harpreet K.; Pietka, Terri; Bullock, Arnold D.; Figenshau, Robert S.; Andriole, Gerald L.; Merrins, Matthew J.; Alexander, Caroline M.; Kimple, Michelle E.; Lamming, Dudley W.

    2016-01-01

    Protein restricted, high carbohydrate diets improve metabolic health in rodents, yet the precise dietary components that are responsible for these effects have not been identified. Further, the applicability of these studies to humans is unclear. Here, we demonstrate in a randomized controlled trial that a moderately protein restricted (PR) diet also improves markers of metabolic health in humans. Intriguingly, we find that feeding mice a diet specifically reduced in branched chain amino acids (BCAAs) is sufficient to improve glucose tolerance and body composition equivalently to a PR diet, via metabolically distinct pathways. Our results highlight a critical role for dietary quality at the level of amino acids in the maintenance of metabolic health, and suggest that diets specifically reduced in BCAAs, or pharmacological interventions in this pathway, may offer a translatable way to achieve many of the metabolic benefits of a PR diet. PMID:27346343

  11. Improved zeolite regeneration processes for preparing saturated branched-chain fatty acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ferrierite zeolite solid is an excellent catalyst for the skeletal isomerization of unsaturated linear-chain fatty acids (i.e., oleic acid) to unsaturated branched-chain fatty acids (i.e., iso-oleic acid) follow by hydrogenation to give saturated branched-chain fatty acids (i.e., isostearic acid). ...

  12. Isostructural unbranched alkyl-chains as tools for stabilizing β-turn structure.

    PubMed

    Kaur, Rajwant; Kishore, Raghuvansh

    2013-07-01

    To investigate the structural role played by isostructural unbranched alkyl-chains on the conformational ensemble and stability of β-turn structures, the conformational properties of a designed model peptide: Plm-Pro-Gly-Pda (1, Plm: H3 C-(CH2)14-CONH-; Pda: -CONH- (CH2 )14 -CH3) have been examined and compared with the parent peptide: Boc-Pro-Gly-NHMe (2, Boc: tert-butoxycarbonyl; NHMe: N-methylamide). The characteristic (13)C NMR chemical-shifts of the Pro C(β) and C(γ) resonances ascertained the incidence of an all-trans peptide-bond in low polarity deuterochloroform solution. Using FTIR and (1) H NMR spectroscopy, we establish that apolar alkyl-chains flanking a β-turn promoting Pro-Gly sequence impart definite incremental stability to the well-defined hydrogen-bonded structure. The assessment of (1)H NMR derived thermodynamic parameters of the hydrogen-bonded amide-NHs via variable temperature indicate that much weaker hydrophobic interactions do contribute to the stability of folded reverse turn structures. The far-UV CD spectral patterns of 1 and 2 in 2,2,2-trifluoroethanol are consistent with Pro-Gly specific type II β-turn structure, concomitantly substantiate that the flanking alkyl-chains induce substantial bias in enhanced β-turn populations. In view of structural as well as functional importance of the Pro-Gly mediated secondary structures, besides biochemical and biological significance of proteins lipidation via myristoylation or palmytoilation, we highlight potential convenience of the unbranched Plm and Pda moieities not only as main-chain N- and C-terminal protecting groups but also to mimic and stabilize specific isolated secondary and supersecondary structural components frequently observed in proteins and polypeptides.

  13. Branched chain amino acid catabolism fuels adipocyte differentiation and lipogenesis

    PubMed Central

    Green, Courtney R.; Wallace, Martina; Divakaruni, Ajit S.; Phillips, Susan A.; Murphy, Anne N.; Ciaraldi, Theodore P.; Metallo, Christian M.

    2015-01-01

    Adipose tissue plays important roles in regulating carbohydrate and lipid homeostasis, though less is known about the regulation of amino acid metabolism in adipocytes. Here we applied isotope tracing to pre–adipocytes and differentiated adipocytes to quantify the contributions of different substrates to tricarboxylic acid metabolism and lipogenesis. In contrast to proliferating cells that use glucose and glutamine for acetyl–coenzyme A (AcCoA) generation, differentiated adipocytes increased branched chain amino acid (BCAA) catabolic flux such that leucine and isoleucine from media and/or protein catabolism accounted for as much as 30% of lipogenic AcCoA pools. Medium cobalamin deficiency caused methylmalonic acid accumulation and odd–chain fatty acid synthesis. B12 supplementation reduced these metabolites and altered the balance of substrates entering mitochondria. Finally, inhibition of BCAA catabolism compromised adipogenesis. These results quantitatively highlight the contribution of BCAAs to adipocyte metabolism and suggest that BCAA catabolism plays a functional role in adipocyte differentiation. PMID:26571352

  14. The effect of the cation alkyl chain length on density and diffusion in dialkylpyrrolidinium bis(mandelato)borate ionic liquids.

    PubMed

    Filippov, Andrei; Taher, Mamoun; Shah, Faiz Ullah; Glavatskih, Sergei; Antzutkin, Oleg N

    2014-12-28

    The physicochemical properties of ionic liquids are strongly affected by the selective combination of the cations and anions comprising the ionic liquid. In particular, the length of the alkyl chains of ions has a clear influence on the ionic liquid's performance. In this paper, we study the self-diffusion of ions in a series of halogen-free boron-based ionic liquids (hf-BILs) containing bis(mandelato)borate anions and dialkylpyrrolidinium cations with long alkyl chains CnH2n+1 with n from 4 to 14 within a temperature range of 293-373 K. It was found that the hf-BILs with n = 4-7 have very similar diffusion coefficients, while hf-BILs with n = 10-14 exhibit two liquid sub-phases in almost the entire temperature range studied (293-353 K). Both liquid sub-phases differ in their diffusion coefficients, while values of the slower diffusion coefficients are close to those of hf-BILs with shorter alkyl chains. To explain the particular dependence of diffusion on the alkyl chain length, we examined the densities of the hf-BILs studied here. It was shown that the dependence of the density on the number of CH2 groups in long alkyl chains of cations can be accurately described using a "mosaic type" model, where regions of long alkyl chains of cations (named 'aliphatic' regions) and the residual chemical moieties in both cations and anions (named 'ionic' regions) give additive contributions. Changes in density due to an increase in temperature and the number of CH2 groups in the long alkyl chains of cations are determined predominantly by changes in the free volume of the 'ionic' regions, while 'aliphatic' regions are already highly compressed by van der Waals forces, which results in only infinitesimal changes in their free volumes with temperature.

  15. Alkyl chain length-dependent surface reaction of dodecahydro-N-alkylcarbazoles on Pt model catalysts

    SciTech Connect

    Gleichweit, Christoph; Amende, Max; Bauer, Udo; Schernich, Stefan; Höfert, Oliver; Lorenz, Michael P. A.; Zhao, Wei; Bachmann, Philipp; Papp, Christian; Müller, Michael; Koch, Marcus; Wasserscheid, Peter; Libuda, Jörg; Steinrück, Hans-Peter

    2014-05-28

    The concept of liquid organic hydrogen carriers (LOHC) holds the potential for large scale chemical storage of hydrogen at ambient conditions. Herein, we compare the dehydrogenation and decomposition of three alkylated carbazole-based LOHCs, dodecahydro-N-ethylcarbazole (H{sub 12}-NEC), dodecahydro-N-propylcarbazole (H{sub 12}-NPC), and dodecahydro-N-butylcarbazole (H{sub 12}-NBC), on Pt(111) and on Al{sub 2}O{sub 3}-supported Pt nanoparticles. We follow the thermal evolution of these systems quantitatively by in situ high-resolution X-ray photoelectron spectroscopy. We show that on Pt(111) the relevant reaction steps are not affected by the different alkyl substituents: for all LOHCs, stepwise dehydrogenation to NEC, NPC, and NBC is followed by cleavage of the C–N bond of the alkyl chain starting at 380–390 K. On Pt/Al{sub 2}O{sub 3}, we discern dealkylation on defect sites already at 350 K, and on ordered, (111)-like facets at 390 K. The dealkylation process at the defects is most pronounced for NEC and least pronounced for NBC.

  16. Diacyltransferase Activity and Chain Length Specificity of Mycobacterium tuberculosis PapA5 in the Synthesis of Alkyl Beta-Diol Lipids

    PubMed Central

    Touchette, Megan H.; Bommineni, Gopal R.; Delle Bovi, Richard J.; Gadbery, John E.; Nicora, Carrie D.; Shukla, Anil K.; Kyle, Jennifer E.; Metz, Thomas O.; Martin, Dwight W.; Sampson, Nicole S.; Miller, W. Todd; Tonge, Peter J.; Seeliger, Jessica C.

    2015-01-01

    Although classified as Gram-positive bacteria, Corynebacterineae possess an asymmetric outer membrane that imparts structural and thereby physiological similarity to more distantly related Gram-negative bacteria. Like lipopolysaccharide in Gram-negative bacteria, lipids in the outer membrane of Corynebacterineae have been associated with the virulence of pathogenic species such as Mycobacterium tuberculosis (Mtb). For example, Mtb strains that lack long, branched-chain alkyl esters known as dimycocerosates (DIMs) are significantly attenuated in model infections. The resultant interest in the biosynthetic pathway of these unusual virulence factors has led to the elucidation of many of the steps leading to the final esterification of the alkyl beta-diol, phthiocerol, with branched-chain fatty acids known as mycocerosates. PapA5 is an acyltransferase implicated in these final reactions. We here show that PapA5 is indeed the terminal enzyme in DIM biosynthesis by demonstrating its dual esterification activity and chain-length preference using synthetic alkyl beta-diol substrate analogues. Applying these analogues to a series of PapA5 mutants, we also revise a model for the substrate binding within PapA5. Finally, we demonstrate that the Mtb Ser/Thr kinases PknB and PknE modify PapA5 on three overlapping Thr residues and a fourth Thr is unique to PknE phosphorylation. These results clarify the DIM biosynthetic pathway and indicate post-translational modifications that warrant further elucidation for their roles in regulation DIM biosynthesis. PMID:26271001

  17. Three new branched chain equations of state based on Wertheim's perturbation theory

    NASA Astrophysics Data System (ADS)

    Marshall, Bennett D.; Chapman, Walter G.

    2013-05-01

    In this work, we present three new branched chain equations of state (EOS) based on Wertheim's perturbation theory. The first represents a slightly approximate general branched chain solution of Wertheim's second order perturbation theory (TPT2) for athermal hard chains, and the second represents the extension of first order perturbation theory with a dimer reference fluid (TPT1-D) to branched athermal hard chain molecules. Each athermal branched chain EOS was shown to give improved results over their linear counterparts when compared to simulation data for branched chain molecules with the branched TPT1-D EOS being the most accurate. Further, it is shown that the branched TPT1-D EOS can be extended to a Lennard-Jones dimer reference system to obtain an equation of state for branched Lennard-Jones chains. The theory is shown to accurately predict the change in phase diagram and vapor pressure which results from branching as compared to experimental data for n-octane and corresponding branched isomers.

  18. Vapor pressures of 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with long alkyl chains.

    PubMed

    Rocha, Marisa A A; Coutinho, João A P; Santos, Luís M N B F

    2014-10-01

    This work presents the vapor pressure at several temperatures for the 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide series, [CN/2CN/2im][NTf2] (N = 14, 16, 18, and 20), measured by a Knudsen effusion method combined with a quartz crystal microbalance. The thermodynamic properties of vaporization of the ionic liquids under study are analysed together with the results obtained previously for the shorter alkyl chain length [CN/2CN/2im][NTf2] (N = 2, 4, 6, 8, 10, and 12), in order to evaluate the effect of the alkyl side chains of the cation and to get additional insights concerning the nanostructuration of ionic liquids. The symmetry effect is explored, based on the comparison with the asymmetric imidazolium based ionic liquids, [CN-1C1im][NTf2]. A trend shift on the thermodynamic properties of vaporization along the alkyl side chains of the extended symmetric ionic liquids, around [C6C6im][NTf2], was detected. An intensification of the odd-even effect was observed starting from [C6C6im][NTf2], with higher enthalpies and entropies of vaporization for the odd numbered ionic liquids, [C7C7im][NTf2] and [C9C9im][NTf2]. Similar, but less pronounced, odd-even effect was found for the symmetric ionic liquids with lower alkyl side chains length, [CN/2CN/2im][NTf2] (with N = 4, 6, 8, 10, and 12). This effect is related with the predominant orientation of the terminal methyl group of the alkyl chain to the imidazolium ring and their influence in the cation-anion interaction. The same Critical Alkyl length at the hexyl, (C6C1and C6C6) was found for both asymmetric and symmetric series indicating that the nanostructuration of the ionic liquids is related with alkyl chain length.

  19. The horizontal transfer of antibiotic resistance genes is enhanced by ionic liquid with different structure of varying alkyl chain length.

    PubMed

    Wang, Qing; Lu, Qian; Mao, Daqing; Cui, Yuxiao; Luo, Yi

    2015-01-01

    Antibiotic resistance genes (ARGs) have become a global health concern. In our previous study, an ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) had been proven to facilitate the dissemination of ARGs in the environment. However, enhanced alkyl group chain length or the substitution of alkyl groups with the cation ring corresponded with increased antimicrobial effects. In this study, we investigated how different structures of ILs with 4, 6, and 8 C atoms in the longer alkyl chain on the imidazolium cations facilitated the dissemination of ARGs. The promotion of plasmid RP4 transfer frequency decreased with [CnMIM][BF4] increasing the alkyl chain length from 4 carbon atoms to 8 carbon atoms on the imidazolium cations, which is observed with [BMIM][BF4] (n = 4, 5.9 fold) > HMIM][BF4] (n = 6, 2.2 fold) > [OMIM][BF4] (n = 8, 1.7 fold). This illustrates that [CnMIM][BF4] with increasing the alkyl chain length exert decreasing ability in facilitating plasmid RP4 horizontal transfer, which is possibly related to IL-structure dependent toxicity. The IL-structure dependent plasmid RP4 transfer frequency was attributable to bacterial cell membrane permeability weaken with increasing alkyl chain length of [CnMIM][PF4], which was evidenced by flow cytometry. In freshwater microcosm, [CnMIm][BF4] promoted the relative abundance of the sulI and intI genes for 4.6 folds, aphA and traF for 5.2 folds higher than the untreated groups, promoting the propagation of ARGs in the aquatic environment. This is the first report that ILs with different structure of varying alkyl chain length facilitate horizontal transfer of plasmid RP4 which is widely distributed in the environment, and thus add the adverse effects of the environmental risk of ILs.

  20. The horizontal transfer of antibiotic resistance genes is enhanced by ionic liquid with different structure of varying alkyl chain length

    PubMed Central

    Wang, Qing; Lu, Qian; Mao, Daqing; Cui, Yuxiao; Luo, Yi

    2015-01-01

    Antibiotic resistance genes (ARGs) have become a global health concern. In our previous study, an ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) had been proven to facilitate the dissemination of ARGs in the environment. However, enhanced alkyl group chain length or the substitution of alkyl groups with the cation ring corresponded with increased antimicrobial effects. In this study, we investigated how different structures of ILs with 4, 6, and 8 C atoms in the longer alkyl chain on the imidazolium cations facilitated the dissemination of ARGs. The promotion of plasmid RP4 transfer frequency decreased with [CnMIM][BF4] increasing the alkyl chain length from 4 carbon atoms to 8 carbon atoms on the imidazolium cations, which is observed with [BMIM][BF4] (n = 4, 5.9 fold) > HMIM][BF4] (n = 6, 2.2 fold) > [OMIM][BF4] (n = 8, 1.7 fold). This illustrates that [CnMIM][BF4] with increasing the alkyl chain length exert decreasing ability in facilitating plasmid RP4 horizontal transfer, which is possibly related to IL-structure dependent toxicity. The IL-structure dependent plasmid RP4 transfer frequency was attributable to bacterial cell membrane permeability weaken with increasing alkyl chain length of [CnMIM][PF4], which was evidenced by flow cytometry. In freshwater microcosm, [CnMIm][BF4] promoted the relative abundance of the sulI and intI genes for 4.6 folds, aphA and traF for 5.2 folds higher than the untreated groups, promoting the propagation of ARGs in the aquatic environment. This is the first report that ILs with different structure of varying alkyl chain length facilitate horizontal transfer of plasmid RP4 which is widely distributed in the environment, and thus add the adverse effects of the environmental risk of ILs. PMID:26379641

  1. Effect of n-alkyl chain length on the complexation of phenanthrene and 9-alkyl-phenanthrene with $beta;-cyclodextrin

    NASA Astrophysics Data System (ADS)

    Rima, J.; Aoun, E.; Hanna, K.

    2004-06-01

    The characteristics of host-guest complexation between β-cyclodextrin (β-CD) and phenanthrene derivatives (phenanthrene, n-propyl, n-butyl and n-hexyl-phenanthrene) were investigated by fluorescence spectrometry. Linear and non-linear regression methods were used to estimate the formation constants ( K1). A 1:1 stoichiometric ratio and an effect of n-alkyl chain length on the formation constant were observed for the binary inclusion complex between guest and β-CD. The formation constant dramatically increases with the length of n-alkyl, it starts from the value of 140 l mol -1 for the phenanthrene to reach the value of 580 l mol -1 for hexyl-phenanthrene. The effect of the temperature on the fluorescence intensity of each complex (guest-host) was also studied; and then the thermodynamic parameters were calculated. The main inclusion site seems to be aromatic moiety for short chain molecules, and it moves toward the alkyl chain part, as the chain becomes longer.

  2. Effect of the alkyl chain length on the rotational dynamics of nonpolar and dipolar solutes in a series of N-alkyl-N-methylmorpholinium ionic liquids.

    PubMed

    Khara, Dinesh Chandra; Kumar, Jaini Praveen; Mondal, Navendu; Samanta, Anunay

    2013-05-01

    Rotational dynamics of two dipolar solutes, 4-aminophthalimide (AP) and 6-propionyl-2-dimethylaminonaphthalene (PRODAN), and a nonpolar solute, anthracene, have been studied in N-alkyl-N-methylmorpholinium (alkyl = ethyl, butyl, hexyl, and octyl) bis(trifluoromethansulfonyl)imide (Tf2N) ionic liquids as a function of temperature and excitation wavelength to probe the microheterogeneous nature of these ionic liquids, which are recently reported to be more structured than the imidazolium ionic liquids (Khara and Samanta, J. Phys. Chem. B2012, 116, 13430-13438). Analysis of the measured rotational time constants of the solutes in terms of the Stokes-Einstein-Debye (SED) hydrodynamic theory reveals that with increase in the alkyl chain length attached to the cationic component of the ionic liquids, AP shows stick to superstick behavior, PRODAN rotation lies between stick and slip boundary conditions, whereas anthracene exhibits slip to sub slip behavior. The contrasting rotational dynamics of these probe molecules is a reflection of their location in distinct environments of the ionic liquids thus demonstrating the heterogeneity of these ionic liquids. The microheterogeneity of these media, in particular, those with the long alkyl chain, is further evidence from the excitation wavelength dependence study of the rotational diffusion of the dipolar probe molecules.

  3. Synthesis of rapeseed biodiesel using short-chained alkyl acetates as acyl acceptor.

    PubMed

    Jeong, Gwi-Taek; Park, Don-Hee

    2010-05-01

    In this study, we conducted experiments using a response surface methodology to determine the optimal reaction conditions for the enzymatic synthesis of biodiesel from rapeseed oil and short-chained alkyl acetates, such as methyl acetate or ethyl acetate, as the acyl acceptor at 40 degrees C. Based on our response surface methodology experiments, the optimal reaction conditions for the synthesis of biodiesel were as follows: methyl acetate as acyl acceptor, catalyst concentration of 16.50%, oil-to-methyl acetate molar ratio of 1:12.44, and reaction time of 19.70 h; ethyl acetate as acyl acceptor, catalyst concentration of 16.95%, oil-to-ethyl acetate molar ratio of 1:12.56, and reaction time of 19.73 h. The fatty acid ester content under the above conditions when methyl acetate and ethyl acetate were used as the acyl acceptor was 58.0% and 62.6%, respectively. The statistical method described in this study can be applied to effectively optimize the enzymatic conditions required for biodiesel production with short-chained alkyl acetates.

  4. Influence of Solute Charge and Pyrrolidinium Ionic Liquid Alkyl Chain Length on Probe Rotational Reorientation Dynamics

    SciTech Connect

    Guo, Jianchang; Mahurin, Shannon Mark; Baker, Gary A; Hillesheim, Patrick C; Dai, Sheng; Shaw, Robert W

    2014-01-01

    In recent years, the effect of molecular charge on the rotational dynamics of probe solutes in room temperature ionic liquids (RTILs) has been a subject of growing interest. For the purpose of extending our understanding of charged solute behavior within RTILs, we have studied the rotational dynamics of three illustrative xanthene fluorescent probes within a series of N-alkylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Cnmpyr][Tf2N]) RTILs with different n-alkyl chain lengths (n = 3, 4, 6, 8, or 10) using time-resolved fluorescence anisotropy decay. The rotational dynamics of the neutral probe rhodamine B dye lies between the stick and slip boundary conditions due to the influence of specific hydrogen bonding interactions. The rotation of the negatively-charged sulforhodamine 640 is slower than that of its positively-charged counterpart rhodamine 6G. An analysis based upon Stokes-Einstein-Debye hydrodynamics indicates that SR640 adheres to stick boundary conditions due to specific interactions, whereas the faster rotation of R6G is attributed to weaker electrostatic interactions. No dependence of the rotational dynamics on the solvent alkyl chain length was observed for any of the three dyes, suggesting that the specific interactions between dyes and RTILs are independent of this solvent parameter.

  5. Synthesis of rapeseed biodiesel using short-chained alkyl acetates as acyl acceptor.

    PubMed

    Jeong, Gwi-Taek; Park, Don-Hee

    2010-05-01

    In this study, we conducted experiments using a response surface methodology to determine the optimal reaction conditions for the enzymatic synthesis of biodiesel from rapeseed oil and short-chained alkyl acetates, such as methyl acetate or ethyl acetate, as the acyl acceptor at 40 degrees C. Based on our response surface methodology experiments, the optimal reaction conditions for the synthesis of biodiesel were as follows: methyl acetate as acyl acceptor, catalyst concentration of 16.50%, oil-to-methyl acetate molar ratio of 1:12.44, and reaction time of 19.70 h; ethyl acetate as acyl acceptor, catalyst concentration of 16.95%, oil-to-ethyl acetate molar ratio of 1:12.56, and reaction time of 19.73 h. The fatty acid ester content under the above conditions when methyl acetate and ethyl acetate were used as the acyl acceptor was 58.0% and 62.6%, respectively. The statistical method described in this study can be applied to effectively optimize the enzymatic conditions required for biodiesel production with short-chained alkyl acetates. PMID:19802734

  6. Peroxisomal beta-oxidation of branched chain fatty acids in rat liver. Evidence that carnitine palmitoyltransferase I prevents transport of branched chain fatty acids into mitochondria.

    PubMed

    Singh, H; Beckman, K; Poulos, A

    1994-04-01

    Fatty acid beta-oxidation was investigated in highly purified mitochondrial and peroxisomal preparations from rat liver. Under isotonic conditions, pristanic and homophytanic acid beta-oxidation in purified peroxisomes was severalfold greater compared to the oxidation in purified mitochondria. Branched chain fatty acid beta-oxidation in purified mitochondria was very low, and the oxidation was not stimulated by exogenous L-carnitine or L-malate. In contrast, stearic acid beta-oxidation by purified mitochondria depended upon exogenous L-carnitine, and the oxidation was stimulated by L-malate. Both mitochondrial and peroxisomal beta-oxidation of branched chain fatty acids was strongly inhibited by fatty acid-free bovine serum albumin, whereas stearic acid oxidation was either unaffected or slightly inhibited by bovine serum albumin. The results presented clearly indicate that branched chain fatty acids are mainly degraded in peroxisomes in rat liver. Branched chain fatty acids were efficiently converted to coenzyme A thioesters by purified mitochondria, peroxisomes, and microsomes. Although pristanic and phytanic acids were rapidly converted to pristanoyl-CoA and phytanoyl-CoA, respectively, they were not converted to carnitine esters by mitochondrial outer membranes. The results indicate that acyl-CoA synthetase and carnitine acyltransferase located at the mitochondrial outer membranes regulate entry of branched chain fatty acids into mitochondria. Mitochondrial carnitine acyltransferase I appears to be highly specific for straight chain fatty acids and restricts entry of branched chain fatty acids into mitochondria. Thus, branched chain fatty acids which cannot be transported across the mitochondrial membranes via the carnitine acyltransferase system are directed to peroxisomes for beta-oxidation. The results reported indicate that phytanic acid, the fatty acid which can be initially degraded by alpha-oxidation due to the presence of a beta-methyl group in the

  7. Effect of branched chain amino acid infusions on body protein metabolism in cirrhosis of liver.

    PubMed Central

    Wright, P D; Holdsworth, J D; Dionigi, P; Clague, M B; James, O F

    1986-01-01

    Thirty seven patients with established cirrhosis of the liver were subjected to measurement of body protein metabolism using L-(1-14C) labelled leucine as a tracer. The effects of disease severity and those of solutions containing 0%, 16%, 35%, 53%, and 100% branched chain amino acids were evaluated. Significant increases in protein synthesis were noted with solutions containing 35%, 53%, and 100% branched chain amino acids, but in patients receiving 100% branched chain amino acids without additional essential amino acid supplement the increase in synthesis was matched by a significant increase in protein breakdown. Protein balance was thus improved only in patients receiving 35% and 53% branched chain amino acids. It was concluded that the high increase in protein breakdown in patients receiving 100% branched chain amino acids was undesirable, and such a solution should not be recommended for clinical use. PMID:3539714

  8. Terthiophene-based D-A polymer with an asymmetric arrangement of alkyl chains that enables efficient polymer solar cells.

    PubMed

    Hu, Huawei; Jiang, Kui; Yang, Guofang; Liu, Jing; Li, Zhengke; Lin, Haoran; Liu, Yuhang; Zhao, Jingbo; Zhang, Jie; Huang, Fei; Qu, Yongquan; Ma, Wei; Yan, He

    2015-11-11

    We report a series of difluorobenzothiadizole (ffBT) and oligothiophene-based polymers with the oligothiophene unit being quaterthiophene (T4), terthiophene (T3), and bithiophene (T2). We demonstrate that a polymer based on ffBT and T3 with an asymmetric arrangement of alkyl chains enables the fabrication of 10.7% efficiency thick-film polymer solar cells (PSCs) without using any processing additives. By decreasing the number of thiophene rings per repeating unit and thus increasing the effective density of the ffBT unit in the polymer backbone, the HOMO and LUMO levels of the T3 polymers are significantly deeper than those of the T4 polymers, and the absorption onset of the T3 polymers is also slightly red-shifted. For the three T3 polymers obtained, the positions and size of the alkyl chains play a critical role in achieving the best PSC performances. The T3 polymer with a commonly known arrangement of alkyl chains (alkyl chains sitting on the first and third thiophenes in a mirror symmetric manner) yields poor morphology and PSC efficiencies. Surprisingly, a T3 polymer with an asymmetric arrangement of alkyl chains (which is later described as having an "asymmetric bi-repeating unit") enables the best-performing PSCs. Morphological studies show that the optimized ffBT-T3 polymer forms a polymer:fullerene morphology that differs significantly from that obtained with T4-based polymers. The morphological changes include a reduced domain size and a reduced extent of polymer crystallinity. The change from T4 to T3 comonomer units and the novel arrangement of alkyl chains in our study provide an important tool to tune the energy levels and morphological properties of donor polymers, which has an overall beneficial effect and leads to enhanced PSC performance.

  9. Branched-chain amino acids and brain function.

    PubMed

    Fernstrom, John D

    2005-06-01

    Branched-chain amino acids (BCAAs) influence brain function by modifying large, neutral amino acid (LNAA) transport at the blood-brain barrier. Transport is shared by several LNAAs, notably the BCAAs and the aromatic amino acids (ArAAs), and is competitive. Consequently, when plasma BCAA concentrations rise, which can occur in response to food ingestion or BCAA administration, or with the onset of certain metabolic diseases (e.g., uncontrolled diabetes), brain BCAA concentrations rise, and ArAA concentrations decline. Such effects occur acutely and chronically. Such reductions in brain ArAA concentrations have functional consequences: biochemically, they reduce the synthesis and the release of neurotransmitters derived from ArAAs, notably serotonin (from tryptophan) and catecholamines (from tyrosine and phenylalanine). The functional effects of such neurochemical changes include altered hormonal function, blood pressure, and affective state. Although the BCAAs thus have biochemical and functional effects in the brain, few attempts have been made to characterize time-course or dose-response relations for such effects. And, no studies have attempted to identify levels of BCAA intake that might produce adverse effects on the brain. The only "model" of very high BCAA exposure is a very rare genetic disorder, maple syrup urine disease, a feature of which is substantial brain dysfunction but that probably cannot serve as a useful model for excessive BCAA intake by normal individuals. Given the known biochemical and functional effects of the BCAAs, it should be a straightforward exercise to design studies to assess dose-response relations for biochemical and functional effects and, in this context, to explore for adverse effect thresholds. PMID:15930466

  10. The Effect of Varying Short-Chain Alkyl Substitution on the Molar Absorptivity and Quantum Yield of Cyanine Dyes

    PubMed Central

    Chapman, Gala; Henary, Maged; Patonay, Gabor

    2011-01-01

    The effect of varying short-chain alkyl substitution of the indole nitrogens on the spectroscopic properties of cyanine dyes was examined. Molar absorptivities and fluorescence quantum yields were determined for a set of pentamethine dyes and a set of heptamethine dyes for which the substitution of the indole nitrogen was varied. For both sets of dyes, increasing alkyl chain length resulted in no significant change in quantum yield or molar absorptivity. These results may be useful in designing new cyanine dyes for analytical applications and predicting their spectroscopic properties. PMID:21760707

  11. Chain branching and termination in the low-temperature combustion of n-alkanes: 2-pentyl radical + O2, isomerization and association of the second O2.

    PubMed

    Asatryan, Rubik; Bozzelli, Joseph W

    2010-07-29

    Association of alkyl radicals with ground-state oxygen (3)Sigma(g)(+)(O(2)) generates chemically activated peroxy intermediates, which can isomerize or further react to form new products before collisional stabilization. The lowest-energy reaction (approximately 19 kcal mol(-1)) for alkylperoxy derivatives of C(3) and larger n-hydrocarbons is an isomerization (intramolecular H-atom transfer) that forms a hydroperoxide alkyl radical, and there is a approximately 30 kcal mol(-1) barrier path to olefin plus HO(2), which is a termination step at lower temperatures. The low-energy-barrier product, hydroperoxide alkyl radical intermediate, can experience additional chemical activation via association with a second oxygen molecule, where there are three important paths that result in chain branching. The competition between this HO(2) + olefin termination step of the first O(2) association and the chain branching processes from the second chemical activation step plays a dominant role at temperatures below 1000 K. Secondary n-pentyl radicals are used in this study as surrogates to analyze the thermochemistry and detailed kinetics of the chemical activation and stabilized adduct reactions important to chain branching and termination. As these radicals provide six- member ring transition states for H-atom transfer between secondary carbons, they represent the detailed kinetics of larger alkane radicals, such as the common fuel components n-heptane and n-decane. Comprehensive potential energy diagrams developed from multilevel CBS-QB3, G3MP2, and CBS-APNO and single-level ab initio and density functional theory methods are used to analyze secondary 2-pentyl (n-pentan-2-yl) and interrelated 2-hydroperoxide-pentan-4-yl radical interactions with O(2). The thermochemistry and kinetics of the chemical activation and stabilized adduct reactions important to chain branching and termination are reported and discussed. Results show that the chain branching reactions have faster

  12. Effects of alkyl chain length on the optoelectronic properties and performance of pyrrolo-perylene solar cells.

    PubMed

    Liu, Xianqing; Kim, Yu Jin; Ha, Yeon Hee; Zhao, Qinghua; Park, Chan Eon; Kim, Yun-Hi

    2015-04-29

    While the impact of alkyl side-chain length on the photovoltaic properties of conjugated polymers and their performance in bulk heterojunction (BHJ) solar cells has been studied extensively, analogous studies on pyrrolo-perylene-based polymers have not received adequate attention. To explore these effects, we synthesized two copolymers based on N-annulated pyrrolo-perylene and consisting of cyano group substituents on thiophene vinylene thiophene units with two different alkyl groups of 2-decyltetradecyl and 7-decylnonadecyl, and we studied them with regard to chemical structure and photovoltaic performance. UV-vis spectroscopy and cyclic voltammetry studies showed that variations in alkyl chain length affect crystallization, light absorption, and the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. These factors have a pronounced impact on the morphology of BHJ thin films and their charge carrier separation and transportation characteristics, which, in turn, influences photovoltaic properties.

  13. Production of branched-chain alcohols by recombinant Ralstonia eutropha in fed-batch cultivation

    SciTech Connect

    Fei, Q; Brigham, CJ; Lu, JN; Fu, RZ; Sinskey, AJ

    2013-09-01

    Branched-chain alcohols are considered promising green energy sources due to their compatibility with existing infrastructure and their high energy density. We utilized a strain of Ralstonia eutropha capable of producing branched-chain alcohols and examined its production in flask cultures. In order to increase isobutanol and 3-methyl-1-butanol (isoamyl alcohol) productivity in the engineered strain, batch, fed-batch, and two-stage fed-batch cultures were carried out in this work. The effects of nitrogen source concentration on branched-chain alcohol production were investigated under four different initial concentrations in fermenters. A maximum 380 g m(-3) of branched-chain alcohol production was observed with 2 kg m(-3) initial NH4Cl concentration in batch cultures. A pH-stat control strategy was utilized to investigate the optimum carbon source amount fed during fed-batch cultures for higher cell density. In cultures of R. eutropha strains that did not produce polyhydroxyalkanoate or branched-chain alcohols, a maximum cell dry weight of 36 kg m(-3) was observed using a fed-batch strategy, when 10 kg m(-3) carbon source was fed into culture medium. Finally, a total branched-chain alcohol titer of 790 g m(-3), the highest branched-chain alcohol yield of 0.03 g g(-1), and the maximum branched-chain alcohol productivity of 8.23 g m(-3) h(-1) were obtained from the engineered strain Re2410/pJL26 in a two-stage fed-batch culture system with pH-stat control. Isobutanol made up over 95% (mass fraction) of the total branched-chain alcohols titer produced in this study. (C) 2013 Published by Elsevier Ltd.

  14. Photocurrent enhancement in diketopyrrolopyrrole solar cells by manipulating dipolar anchoring terminals on alkyl-chain spacers.

    PubMed

    Tang, Ailing; Lu, Zhenhuan; Bai, Shuming; Huang, Jianhua; Chen, Yuxia; Shi, Qiang; Zhan, Chuanlang; Yao, Jiannian

    2014-03-01

    We chose DPP-BDT-DPP {DPP=diketopyrrolopyrrole, BDT=4,8-di-[2-(2-ethylhexyl)-thienyl]benzo[1,2-b:4,5-b']dithiophene} as a model backbone and varied the anchoring groups [C5 H11 , COOCH3 , and SiCH3 (OSiCH3 )2 ] terminated on the N-substituted alkyl-chain spacer of the DPP units to study the effect of anchoring terminals on the morphology of blend film and on the device performances of bulk heterojunction solar cells. By replacing the nonpolar C5 H11 anchoring terminal with the polar COOCH3 anchoring terminal leads to an enhancement in the short-circuit current density (Jsc ) (4.62 vs. 9.32 mA cm(-2) ), whereas the value of Jsc sharply decreases to 0.45 mA cm(-2) if the C5 H11 anchoring terminal is replaced by a SiCH3 (OSiCH3 )2 group. The changes in Jsc are associated with changes in the π-π stacking distance (3.39→3.34 Å vs. 3.39→3.45 Å) and the phase size (50→20 nm vs. 50→>250 nm) through alteration of the anchoring group from C5 H11 to COOCH3 versus from C5 H11 to SiCH3 (OSiCH3 )2 . Interestingly, the anchoring terminals bring about drastic changes in molecular orientations, which result in different out-of-plane hole transport. This is the first time this effect has been systemically demonstrated to improve photocurrent generation by manipulating the dipolar anchoring groups terminated on the alkyl-chain spacer.

  15. Disappearance of criticality in a branched-chain thermal explosion with heat loss

    SciTech Connect

    Okoya, S.S.

    2006-01-01

    Branched-chain thermal explosions involving simplified initiation, branching, and termination of chains, as well as heat exchange with the surroundings, are considered, but it is assumed that consumption of fuel is negligible for combustion in a mixture of H{sub 2}+O{sub 2} that covers nth Arrhenius kinetics for the chain-branching step. In particular, the effect of heat loss on the problem is considered, Mostly analytical investigations of the simplified model are presented using standard Semenov's techniques. The analytical method provides expressions for criticality and the transition points. Also, the different qualitative effects of varying the dimensionless parameters are investigated.

  16. Influence of alkyl chain length on calcium phosphate deposition onto titanium surfaces modified with alkylphosphonic acid monolayers.

    PubMed

    Wu, Jiang; Hirata, Isao; Zhao, Xianghui; Gao, Bo; Okazaki, Masayuki; Kato, Koichi

    2013-08-01

    Much attention has been paid to the modification of a titanium surface with an alkylphosphonic acid (PA)-based self-assembled monolayer (SAM) to accelerate hydroxyapatite (HA) deposition on the surface. In order to further accelerate the rate of HA deposition, we examined here the effect of alkyl chain length of SAMs on the formation of a HA layer. PAs with three different alkyl chain lengths (3, 6, and 16 methylene units) were used for the preparation of a SAM on titanium. The titanium specimens with monolayers were soaked in a simulated body fluid under physiological conditions for 4 weeks. The deposited substances were analyzed by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. These analyses revealed that the formation of PA SAMs accelerate the deposition of poorly crystallized HA, in an alkyl chain length-dependent manner. Among PAs studied here, PA containing a 16-carbon alkyl chain gave rise to the titanium surface most effective for the deposition of HA.

  17. Regulation of hepatic branched-chain alpha-keto acid dehydrogenase complex in rats fed a high-fat diet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: Branched-chain alpha-keto acid dehydrogenase complex (BCKDC) regulates branched-chain amino acid (BCAA) metabolism at the level of branched chain alpha-ketoacid (BCKA) catabolism. It has been demonstrated that the activity of hepatic BCKDC is markedly decreased in type 2 diabetic animal...

  18. Marine Chloroflexus-like Organisms Synthesize Mid-Chain Branched Monomethylalkanes

    NASA Astrophysics Data System (ADS)

    Parenteau, M. N.; Jahnke, L. L.; Green, S. J.; Boomer, S. M.; Pierson, B. K.

    2010-04-01

    Mid-chain branched mono- and dimethylalkanes (MMA and DMA, respectively) are considered biomarkers for cyanobacteria. In this study, we report the synthesis of a series of MMAs by anoxygenic phototrophic marine Chloroflexus-like organisms (MCLOs).

  19. Chain-length-dependent conformational transformation and melting behaviour of alkyl/oligo(oxyethylene)/alkyl triblock compounds: alpha-octyl-omega-octyloxyoligo(oxyethylene)s.

    PubMed

    Fukuhara, Koichi; Mizawa, Takahiro; Inoue, Tomohiro; Kumamoto, Hirotaka; Terai, Yoshihide; Matsuura, Hiroatsu; Viras, Kyriakos

    2005-04-01

    The chain-length-dependent conformational transformation and the melting behaviour of triblock compounds alpha-octyl-omega-octyloxyoligo(oxyethylene)s, H(CH2)8(OCH2CH2)mO(CH2)8H (abbreviated as C8EmC8) (m = 1-8), have been studied by infrared spectroscopy and differential scanning calorimetry. The compounds with m = 1-5 assume the all-trans planar form (gamma-form) in the solid state, while those with m = 7 and 8 assume the planar/ helical/planar form with conformational defects in the alkyl chain (beta'-form). Conformational polymorphism was observed for C8E6C8: the gamma-form for the annealed solid and the planar/helical/planar form without conformational defects (beta-form) for the unannealed solid. The conformational transformation from the planar form into the planar/helical/planar form takes place at a length of the oligo(oxyethylene) chain m = 6. This result for C8EmC8 and a similar conformational transformation for C6EmC6 at m = 5 (previous work) demonstrate that the conformation of the CnEmCn triblock compounds in the solid state is determined by intramolecular conformational restoring force in the central oligo(oxyethylene) block, intermolecular dipole-dipole interaction of the C-O bonds and intermolecular packing force in the end alkyl blocks. The melting points of the gamma-form solid of C8EmC8 are much lower than the melting points of n-alkanes with similar molecular masses. The observed thermodynamic quantities show that the planar structure of the oligo(oxyethylene) chain is stabilized by the force of the magnitude that maintains the rotator phase of n-alkanes. For the beta'-form solid of C8EmC8, the alkyl blocks, which are partially noncrystalline, and the oligo(oxyethylene) block melt together at the melting point, unlike the beta-form solid of C6EmC6, for which the melting of the alkyl blocks takes place before the melting of the oligo(oxyethylene) block. The beta-form solid of C8E6C8 (unannealed) melts via the gamma-form solid.

  20. Vapor pressures of 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with long alkyl chains

    SciTech Connect

    Rocha, Marisa A. A. E-mail: marisa.alexandra.rocha@gmail.com; Coutinho, João A. P.; Santos, Luís M. N. B. F. E-mail: marisa.alexandra.rocha@gmail.com

    2014-10-07

    This work presents the vapor pressure at several temperatures for the 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide series, [C{sub N/2}C{sub N/2}im][NTf{sub 2}] (N = 14, 16, 18, and 20), measured by a Knudsen effusion method combined with a quartz crystal microbalance. The thermodynamic properties of vaporization of the ionic liquids under study are analysed together with the results obtained previously for the shorter alkyl chain length [C{sub N/2}C{sub N/2}im][NTf{sub 2}] (N = 2, 4, 6, 8, 10, and 12), in order to evaluate the effect of the alkyl side chains of the cation and to get additional insights concerning the nanostructuration of ionic liquids. The symmetry effect is explored, based on the comparison with the asymmetric imidazolium based ionic liquids, [C{sub N-1}C{sub 1}im][NTf{sub 2}]. A trend shift on the thermodynamic properties of vaporization along the alkyl side chains of the extended symmetric ionic liquids, around [C{sub 6}C{sub 6}im][NTf{sub 2}], was detected. An intensification of the odd-even effect was observed starting from [C{sub 6}C{sub 6}im][NTf{sub 2}], with higher enthalpies and entropies of vaporization for the odd numbered ionic liquids, [C{sub 7}C{sub 7}im][NTf{sub 2}] and [C{sub 9}C{sub 9}im][NTf{sub 2}]. Similar, but less pronounced, odd-even effect was found for the symmetric ionic liquids with lower alkyl side chains length, [C{sub N/2}C{sub N/2}im][NTf{sub 2}] (with N = 4, 6, 8, 10, and 12). This effect is related with the predominant orientation of the terminal methyl group of the alkyl chain to the imidazolium ring and their influence in the cation-anion interaction. The same Critical Alkyl length at the hexyl, (C{sub 6}C{sub 1}and C{sub 6}C{sub 6}) was found for both asymmetric and symmetric series indicating that the nanostructuration of the ionic liquids is related with alkyl chain length.

  1. Selective microbial degradation of saturated methyl branched chain fatty acid isomers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three strains of Pseudomonas bacteria were screened for their capabilities of degrading chemically synthesized saturated branched-chain fatty acids (sbc-FAs). Mixtures of sbc-FAs with the methyl-branch located at various locales along the fatty acid were used as a carbon feedstock in shake-flask cu...

  2. Branched Chain Amino Acid Metabolism in the Biosynthesis of Lycopersicon pennellii Glucose Esters 1

    PubMed Central

    Walters, Donald S.; Steffens, John C.

    1990-01-01

    Lycopersicon pennellii Corr. (D'Arcy) an insect-resistant, wild tomato possesses high densities of glandular trichomes which exude a mixture of 2,3,4-tri-O-acylated glucose esters that function as a physical impediment and feeding deterrent to small arthropod pests. The acyl moieties are branched C4 and C5 acids, and branched and straight chain C10, C11, and C12 acids. The structure of the branched acyl constituents suggests that the branched chain amino acid biosynthetic pathway participates in their biosynthesis. [14C]Valine and deuterated branched chain amino acids (and their oxo-acid derivatives) were incorporated into branched C4 and C5 acid groups of glucose esters by a process of transamination, oxidative decarboxylation and subsequent acylation. C4 and C5 branched acids were elongated by two carbon units to produce the branched C10-C12 groups. Norvaline, norleucine, allylglycine, and methionine also were processed into acyl moieties and secreted from the trichomes as glucose esters. Changes in the acyl composition of the glucose esters following sulfonylurea herbicide administration support the participation of acetohydroxyacid synthetase and the other enzymes of branched amino acid biosynthesis in the production of glucose esters. PMID:16667654

  3. Alkyl Chain Length and Temperature Effects on Structural Properties of Pyrrolidinium-Based Ionic Liquids: A Combined Atomistic Simulation and Small-Angle X-ray Scattering Study.

    SciTech Connect

    Li, Song; Banuelos, Jose Leo; Guo, Jianchang; Anovitz, Lawrence {Larry} M; Rother, Gernot; Shaw, Robert W; Hillesheim, Patrick C; Dai, Sheng; Baker, Gary A; Cummings, Peter T

    2011-01-01

    Molecular dynamics (MD) simulations of 1-alkyl-1-methylpyrrolidinium 12 bis(trifluoromethanesulfonyl)imide ([CnMPy][Tf2N], n = 3, 4, 6, 8, 10) were conducted 13 using an all-atom model. Radial distribution functions (RDF) were computed and structure 14 functions were generated to compare with new X-ray scattering experimental results, 15 reported herein. The scattering peaks in the structure functions generally shift to lower Q 16 values with increased temperature for all the liquids in this series. However, the first sharp 17 diffraction peak (FSDP) in the longer alkyl chain liquids displays a marked shift to higher Q 18 values with increasing temperature. Alkyl chain-dependent ordering of the polar groups and 19 increased tail aggregation with increasing alkyl chain length were observed in the partial pair 20 correlation functions and the structure functions. The reasons for the observed alkyl chain- 21 dependent phenomena and temperature effects were explored.

  4. Alkyl Chain Length and Temperature Effects on Structural Properties of Pyrrolidinium-Based Ionic Liquids: A Combined Atomistic Simulation and Small-Angle X-ray Scattering Study

    SciTech Connect

    Li, Song; Bañuelos, José Leobardo; Guo, Jianchang; Anovitz, Lawrence; Rother, Gernot; Shaw, Robert W.; Hillesheim, Patrick C.; Dai, Sheng; Baker, Gary A.; Cummings, Peter T.

    2011-12-21

    Molecular dynamics (MD) simulations of 1-alkyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([CnMPy][Tf₂N], n = 3, 4, 6, 8, 10) were conducted using an all-atom model. Radial distribution functions (RDF) were computed and structure functions were generated to compare with new X-ray scattering experimental results, reported herein. The scattering peaks in the structure functions generally shift to lower Q values with increased temperature for all the liquids in this series. However, the first sharp diffraction peak (FSDP) in the longer alkyl chain liquids displays a marked shift to higher Q values with increasing temperature. Alkyl chain-dependent ordering of the polar groups and increased tail aggregation with increasing alkyl chain length were observed in the partial pair correlation functions and the structure functions. The reasons for the observed alkyl chain-dependent phenomena and temperature effects were explored.

  5. [Odd- and branched-chain fatty acids in milk fat--characteristic and health properties].

    PubMed

    Adamska, Agata; Rutkowska, Jarosława

    2014-01-01

    This review analyzes the current state of knowledge on odd- and branched-chain fatty acids present in milk fat. Special attention is devoted to the characteristic, synthesis in ruminants, factors affecting their content in milk fat and pro-health properties of these compounds. The group of odd- and branched-chain fatty acids includes mainly saturated fatty acids with one or more methyl branches in the iso or anteiso position. These fatty acids are largely derived from ruminal bacteria and they have been transferred to ruminant tissue (milk and meat). For that reason they have been used as biomarkers of rumen fermentation. Odd- and branched-chain fatty acids are exogenous products for humans, and therefore have specific properties. The results of research from recent decades show that odd- and branched-chain fatty acids have anti-cancer activity. Branched-chain fatty acids may reduce the incidence of necrotizing enterocolitis. Additionally, these compounds have a beneficial effect on proper tissue function and on functioning and development of the infant gut, whereas odd-chain fatty acids are considered as biomarkers of milk fat intake by humans. So far, not all the mechanisms of activity of these compounds are known thoroughly. They should be more carefully studied for application of their biological effects in prevention and treatment. PMID:25228507

  6. Langmuir Monolayers of Straight-Chain And Branched Hexadecanol And Eicosanol Mixtures

    SciTech Connect

    Kurtz, R.E.; Toney, M.F.; Pople, J.A.; Lin, B.; Meron, M.; Majewski, J.; Lange, A.; Fuller, G.G.

    2009-05-20

    Langmuir monolayers of straight-chain and branched hexadecanol and eicosanol mixtures were previously studied using surface pressure-area isotherms, Brewster angle microscopy, and interfacial rheology. In this paper, we investigate the structure of these fatty alcohol mixtures using these previous results together with X-ray diffraction and reflectivity measurements, which provide a better understanding of the structure of the monolayer in terms of the phase segregation and location of branched chains. For eicosanol below 25 mN/m, the branched chains are incorporated into the monolayer, yet they are phase-separated from the straight chains. At higher surface pressures, the branched chains are expelled from the monolayer and presumably form micelles or some other aggregate in the subphase. In contrast, the hexadecanol branched chains are not present in the monolayer at any surface pressure. These behaviors are interpreted with the help of the X-ray measurements and density profiles, and are explained in terms of straight-chain flexibility. We will discuss the effect of the monolayer structure on the surface shear viscosity. These studies provide a deeper understanding of the structure and behavior of amphiphilic mixtures, and will ultimately aid in developing models for lipids, micelle formation, and other important biological functions.

  7. Langmuir Monolayers of Straight-Chain and Branched Hexadecanol and Eicosanol Mixtures

    SciTech Connect

    Kurtz, R.E.; Toney, M.F.; Pople, J.A.; Lin, B.; Meron, M.; Majewski, J.; Lange, A.; Fuller, G.G.

    2009-01-06

    Langmuir monolayers of straight-chain and branched hexadecanol and eicosanol mixtures were previously studied using surface pressure-area isotherms, Brewster angle microscopy, and interfacial rheology. In this paper, we investigate the structure of these fatty alcohol mixtures using these previous results together with X-ray diffraction and reflectivity measurements, which provide a better understanding of the structure of the monolayer in terms of the phase segregation and location of branched chains. For eicosanol below 25 mN/m, the branched chains are incorporated into the monolayer, yet they are phase-separated from the straight chains. At higher surface pressures, the branched chains are expelled from the monolayer and presumably form micelles or some other aggregate in the subphase. In contrast, the hexadecanol branched chains are not present in the monolayer at any surface pressure. These behaviors are interpreted with the help of the X-ray measurements and density profiles, and are explained in terms of straight-chain flexibility. We will discuss the effect of the monolayer structure on the surface shear viscosity. These studies provide a deeper understanding of the structure and behavior of amphiphilic mixtures, and will ultimately aid in developing models for lipids, micelle formation, and other important biological functions.

  8. Modulation of mutagenic properties in a series of DNA-directed alkylating agents by variation of chain length and alkylator reactivity.

    PubMed

    Ferguson, L R; Turner, P M; Pogai, H; Denny, W A

    1992-02-01

    Four series of aniline mustards linked to a DNA-affinic acridine chromophore by alkyl chains of varying length (2-5 carbon atoms) have been studied for their mutagenic properties, as estimated in four strains of Salmonella typhimurium and in Saccharomyces cerevisiae strain D5. The four series have very different mustard reactivities, as determined by the aniline link group (-O-, -CH2-, -S- or -SO2-). Some of the derived compounds cause frameshift mutagenesis which can be detected in TA98 and also "petite" mutagenesis activity, neither of which occur to significant extents with the parent mustards or with 9-aminoacridine. None of the derived compounds are as effective as the parent mustards in mitotic crossing-over, nor do they show ability for frameshift mutagenesis in S. typhimurium TA1977 which is typical of acridines. Some of the compounds have comparable frameshift activity to compounds such as ICR-191, but appear to have a different base-pair preference. The results indicate clear structure-activity relationships for the spectrum of mutagenic activity, which relate to both chain length and alkylator reactivity, for these compounds.

  9. A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids

    PubMed Central

    Zheng, Xiaojiao; Qiu, Yunping; Zhong, Wei; Baxter, Sarah; Su, Mingming; Li, Qiong; Xie, Guoxiang; Ore, Brandon M.; Qiao, Shanlei; Spencer, Melanie D.; Zeisel, Steven H.; Zhou, Zhanxiang; Zhao, Aihua; Jia, Wei

    2013-01-01

    Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography mass spectrometry (GC-MS) analysis. A one-step derivatization using 100 µL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency. The best extraction efficiency of the derivatized products was achieved by a two-step extraction with hexane. The method exhibited good derivatization efficiency and recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations (RSDs) of all targeted compounds showed good intra- and inter-day (within 7 days) precision (< 10%), and good stability (< 20%) within 4 days at room temperature (23–25 °C), or 7 days when stored at −20 °C. We applied our method to measure SCFA and BCAA levels in fecal samples from rats administrated with different diet. Both univariate and multivariate statistics analysis of the concentrations of these target metabolites could differentiate three groups with ethanol intervention and different oils in diet. This method was also successfully employed to determine SCFA and BCAA in the feces, plasma and urine from normal humans, providing important baseline information of the concentrations of these metabolites. This novel metabolic profile study has great potential for translational research. PMID:23997757

  10. Studies on the production of branched-chain alcohols in engineered Ralstonia eutropha

    SciTech Connect

    Lu, JN; Brigham, CJ; Gai, CS; Sinskey, AJ

    2012-08-04

    Wild-type Ralstonia eutropha H16 produces polyhydroxybutyrate (PHB) as an intracellular carbon storage material during nutrient stress in the presence of excess carbon. In this study, the excess carbon was redirected in engineered strains from PHB storage to the production of isobutanol and 3-methyl-1-butanol (branched-chain higher alcohols). These branched-chain higher alcohols can directly substitute for fossil-based fuels and be employed within the current infrastructure. Various mutant strains of R. eutropha with isobutyraldehyde dehydrogenase activity, in combination with the overexpression of plasmid-borne, native branched-chain amino acid biosynthesis pathway genes and the overexpression of heterologous ketoisovalerate decarboxylase gene, were employed for the biosynthesis of isobutanol and 3-methyl-1-butanol. Production of these branched-chain alcohols was initiated during nitrogen or phosphorus limitation in the engineered R. eutropha. One mutant strain not only produced over 180 mg/L branched-chain alcohols in flask culture, but also was significantly more tolerant of isobutanol toxicity than wild-type R. eutropha. After the elimination of genes encoding three potential carbon sinks (ilvE, bkdAB, and aceE), the production titer improved to 270 mg/L isobutanol and 40 mg/L 3-methyl-1-butanol. Semicontinuous flask cultivation was utilized to minimize the toxicity caused by isobutanol while supplying cells with sufficient nutrients. Under this semicontinuous flask cultivation, the R. eutropha mutant grew and produced more than 14 g/L branched-chain alcohols over the duration of 50 days. These results demonstrate that R. eutropha carbon flux can be redirected from PHB to branched-chain alcohols and that engineered R. eutropha can be cultivated over prolonged periods of time for product biosynthesis.

  11. A comparative study of straight chain and branched chain fatty acid oxidation in skin fibroblasts from patients with peroxisomal disorders.

    PubMed

    Singh, H; Usher, S; Johnson, D; Poulos, A

    1990-02-01

    The beta-oxidation of stearic acid and of alpha- and gamma-methyl isoprenoid-derived fatty acids (pristanic and tetramethylheptadecanoic acids, respectively) was investigated in normal skin fibroblasts and in fibroblasts from patients with inherited defects in peroxisomal biogenesis. Stearic acid beta-oxidation by normal fibroblast homogenates was several-fold greater compared to the oxidation of the two branched chain fatty acids. The effect of phosphatidylcholine, alpha-cyclodextrin, and bovine serum albumin on the three activities suggests that different enzymes are involved in the beta-oxidation of straight chain and branched chain fatty acids. Homogenates of fibroblasts from patients with a deficiency in peroxisomes (Zellweger syndrome and infantile Refsum's disease) showed a normal ability to beta-oxidize stearic acid, but the oxidation of pristanic and tetramethylheptadecanoic acid was decreased. Concomitantly, 14CO2 production from the branched chain fatty acids by Zellweger fibroblasts in culture (but not from stearic acid) was greatly diminished. The Zellweger fibroblasts also showed a marked reduction in the amount of water-soluble metabolites from the radiolabeled branched chain fatty acids that are released into the culture medium. The data presented indicate that the oxidation of alpha- and gamma-methyl isoprenoid-derived fatty acids takes place largely in peroxisomes in human skin fibroblasts.

  12. Influence of alkyl chain length on the surface activity of antibacterial polymers derived from ROMP.

    PubMed

    Altay, Esra; Yapaöz, Melda Altıkatoğlu; Keskin, Bahadır; Yucesan, Gundoğ; Eren, Tarik

    2015-03-01

    The purpose of this study is to understand the antibacterial properties of cationic polymers on solid surfaces by investigating the structure-activity relationships. The polymer synthesis was carried via ring opening metathesis polymerization (ROMP) of oxanorbornene derivatives. Modulation of molecular weights and alkyl chain lengths of the polymers were studied to investigate the antibacterial properties on the glass surface. Fluorescein (Na salt) staining contact angle measurements were used to characterize the positive charge density and hydrophobicity on the polymer coated surfaces. Positive charge density for the surface coated polymers with molecular weights of 3000 and 10,000 g mol(-1) is observed to be in the range of 2.3-28.5 nmol cm(-2). The ROMP based cationic pyridinium polymer with hexyl unit exhibited the highest bactericidal efficiency against Escherichia coli on solid surface killing 99% of the bacteria in 5 min. However, phenyl and octyl functionalized quaternary pyridinium groups exhibited lower biocidal properties on the solid surfaces compared to their solution phase biocidal properties. Studying the effect of threshold polymer concentrations on the antibacterial properties indicated that changing the concentrations of polymer coatings on the solid surface dramatically influences antibacterial efficiency.

  13. Alkyl Chain Growth on a Transition Metal Center: How Does Iron Compare to Ruthenium and Osmium?

    PubMed Central

    Sainna, Mala A.; de Visser, Sam P.

    2015-01-01

    Industrial Fischer-Tropsch processes involve the synthesis of hydrocarbons usually on metal surface catalysts. On the other hand, very few homogeneous catalysts are known to perform a Fischer-Tropsch style of reaction. In recent work, we established the catalytic properties of a diruthenium-platinum carbene complex, [(CpRu)2(μ2-H)(μ2-NHCH3)(μ3-C)PtCH3(P(CH3)3)2](CO)n+ with n = 0, 2 and Cp = η5-C5(CH3)5, and showed it to react efficiently by initial hydrogen atom transfer followed by methyl transfer to form an alkyl chain on the Ru-center. In particular, the catalytic efficiency was shown to increase after the addition of two CO molecules. As such, this system could be viewed as a potential homogeneous Fischer-Tropsch catalyst. Herein, we have engineered the catalytic center of the catalyst and investigated the reactivity of trimetal carbene complexes of the same type using iron, ruthenium and osmium at the central metal scaffold. The work shows that the reactivity should increase from diosmium to diruthenium to diiron; however, a non-linear trend is observed due to multiple factors contributing to the individual barrier heights. We identified all individual components of these reaction steps in detail and established the difference in reactivity of the various complexes. PMID:26426009

  14. Imidiazolium based ionic liquids: effects of different anions and alkyl chains lengths on the barley seedlings.

    PubMed

    Cvjetko Bubalo, Marina; Hanousek, Karla; Radošević, Kristina; Gaurina Srček, Višnja; Jakovljević, Tamara; Radojčić Redovniković, Ivana

    2014-03-01

    We studied the effects of five imidiazolium based ionic liquids with different anions and length of alkyl chains linked to imidazolium ring on the early development of barley (Hordeum vulgare). The inhibitory effect depends on the ionic liquids concentration and chemical structure, whereby the most toxic one was [C10mim][Br], followed by [C7mim][Br], [C4mim][Br], [C4mim][CH3CO2] and [C4mim][BF4]. Both anion and cation structures affected the toxicity of ionic liquid indicating that selection of more biocompatible anions such as [CH3CO2] does not necessarily indicate lower toxicity. Alternation in the extent of oxidative stress and antioxidant enzymes activities were found in barley plants due to ionic liquid treatments. When seedlings were exposed to higher concentrations of ionic liquids, antioxidant system could not effectively remove reactive oxidative species, leading to lipid peroxidation and damage of the photosynthetic system. However, overall data indicated that the performance of barley seedling was improved when all measured enzymes involved in scavenging of reactive oxygen species (ROS) were increased with special emphasis on GPX activities. Since there are no studies about ionic liquid (IL) toxicity in plants, that simultaneously evaluates the antioxidative enzyme system in response to different ILs, this work is valuable for gaining knowledge about the protection mechanism of plants from oxidative stress caused by IL exposure.

  15. Thermal stability and ordering study of long- and short-alkyl chain phosphonic acid multilayers.

    PubMed

    de Pauli, Muriel; Prado, Mariana de Castro; Matos, Matheus Josue Souza; Fontes, Giselle Nogueira; Perez, Carlos Alberto; Mazzoni, Mario Sergio Carvalho; Neves, Bernardo Ruegger Almeida; Malachias, Angelo

    2012-10-30

    Long-range order evolution of self-assembled phosphonic acid multilayers as a function of temperature is studied here for two molecules with different alkyl chain length. By using synchrotron conventional diffraction, distinct order configurations are retrieved on phosphonic acid multilayers and their thermodynamic behavior monitored by energy-dispersive diffraction. This later technique allows us to observe the system behavior near order-disorder temperatures, as well as to determine the most stable configurations in the range from room temperature up to 120 °C. Planar order is also addressed by wide-angle X-ray scattering (WAXS) transmission experiments. Order parameter phase diagrams are built based on the experimental results, showing the dominant configuration at each temperature. The multilayer molecular long-range order retrieved from the experiments is corroborated by first principles calculations based on the Density Functional Theory. The bulk configurations depicted in this work are produced by molecule-molecule interactions and allow for future comparisons with the behavior of ordered molecules in few-monolayers configurations, commonly used in organic devices, where the presence of surfaces and interfaces strongly affects the molecule packing.

  16. Alkyl Chain Growth on a Transition Metal Center: How Does Iron Compare to Ruthenium and Osmium?

    PubMed

    Sainna, Mala A; de Visser, Sam P

    2015-09-28

    Industrial Fischer-Tropsch processes involve the synthesis of hydrocarbons usually on metal surface catalysts. On the other hand, very few homogeneous catalysts are known to perform a Fischer-Tropsch style of reaction. In recent work, we established the catalytic properties of a diruthenium-platinum carbene complex, [(CpRu)₂(μ²-H) (μ²-NHCH₃)(μ³-C)PtCH₃(P(CH₃)₃)₂](CO)n⁺ with n=0, 2 and Cp=η⁵-C₅(CH₃)₅, and showed it to react efficiently by initial hydrogen atom transfer followed by methyl transfer to form an alkyl chain on the Ru-center. In particular, the catalytic efficiency was shown to increase after the addition of two CO molecules. As such, this system could be viewed as a potential homogeneous Fischer-Tropsch catalyst. Herein, we have engineered the catalytic center of the catalyst and investigated the reactivity of trimetal carbene complexes of the same type using iron, ruthenium and osmium at the central metal scaffold. The work shows that the reactivity should increase from diosmium to diruthenium to diiron; however, a non-linear trend is observed due to multiple factors contributing to the individual barrier heights. We identified all individual components of these reaction steps in detail and established the difference in reactivity of the various complexes.

  17. Alkyl Chain Growth on a Transition Metal Center: How Does Iron Compare to Ruthenium and Osmium?

    PubMed

    Sainna, Mala A; de Visser, Sam P

    2015-01-01

    Industrial Fischer-Tropsch processes involve the synthesis of hydrocarbons usually on metal surface catalysts. On the other hand, very few homogeneous catalysts are known to perform a Fischer-Tropsch style of reaction. In recent work, we established the catalytic properties of a diruthenium-platinum carbene complex, [(CpRu)₂(μ²-H) (μ²-NHCH₃)(μ³-C)PtCH₃(P(CH₃)₃)₂](CO)n⁺ with n=0, 2 and Cp=η⁵-C₅(CH₃)₅, and showed it to react efficiently by initial hydrogen atom transfer followed by methyl transfer to form an alkyl chain on the Ru-center. In particular, the catalytic efficiency was shown to increase after the addition of two CO molecules. As such, this system could be viewed as a potential homogeneous Fischer-Tropsch catalyst. Herein, we have engineered the catalytic center of the catalyst and investigated the reactivity of trimetal carbene complexes of the same type using iron, ruthenium and osmium at the central metal scaffold. The work shows that the reactivity should increase from diosmium to diruthenium to diiron; however, a non-linear trend is observed due to multiple factors contributing to the individual barrier heights. We identified all individual components of these reaction steps in detail and established the difference in reactivity of the various complexes. PMID:26426009

  18. Communication: Role of short chain branching in polymer structure and dynamics.

    PubMed

    Kim, Jun Mo; Baig, Chunggi

    2016-02-28

    A comprehensive understanding of chain-branching effects, essential for establishing general knowledge of the structure-property-phenomenon relationship in polymer science, has not yet been found, due to a critical lack of knowledge on the role of short-chain branches, the effects of which have mostly been neglected in favor of the standard entropic-based concepts of long polymers. Here, we show a significant effect of short-chain branching on the structural and dynamical properties of polymeric materials, and reveal the molecular origins behind the fundamental role of short branches, via atomistic nonequilibrium molecular dynamics and mesoscopic Brownian dynamics by systematically varying the strength of the mobility of short branches. We demonstrate that the fast random Brownian kinetics inherent to short branches plays a key role in governing the overall structure and dynamics of polymers, leading to a compact molecular structure and, under external fields, to a lesser degree of structural deformation of polymer, to a reduced shear-thinning behavior, and to a smaller elastic stress, compared with their linear analogues. Their fast dynamical nature being unaffected by practical flow fields owing to their very short characteristic time scale, short branches would substantially influence (i.e., facilitate) the overall relaxation behavior of polymeric materials under various flowing conditions. PMID:26931673

  19. Communication: Role of short chain branching in polymer structure and dynamics

    NASA Astrophysics Data System (ADS)

    Kim, Jun Mo; Baig, Chunggi

    2016-02-01

    A comprehensive understanding of chain-branching effects, essential for establishing general knowledge of the structure-property-phenomenon relationship in polymer science, has not yet been found, due to a critical lack of knowledge on the role of short-chain branches, the effects of which have mostly been neglected in favor of the standard entropic-based concepts of long polymers. Here, we show a significant effect of short-chain branching on the structural and dynamical properties of polymeric materials, and reveal the molecular origins behind the fundamental role of short branches, via atomistic nonequilibrium molecular dynamics and mesoscopic Brownian dynamics by systematically varying the strength of the mobility of short branches. We demonstrate that the fast random Brownian kinetics inherent to short branches plays a key role in governing the overall structure and dynamics of polymers, leading to a compact molecular structure and, under external fields, to a lesser degree of structural deformation of polymer, to a reduced shear-thinning behavior, and to a smaller elastic stress, compared with their linear analogues. Their fast dynamical nature being unaffected by practical flow fields owing to their very short characteristic time scale, short branches would substantially influence (i.e., facilitate) the overall relaxation behavior of polymeric materials under various flowing conditions.

  20. Anti-Biofilm Efficacy of Dual-Action Nitric Oxide-Releasing Alkyl Chain Modified Poly(amidoamine) Dendrimers.

    PubMed

    Worley, Brittany V; Schilly, Kelci M; Schoenfisch, Mark H

    2015-05-01

    Herein, we describe the synthesis of nitric oxide (NO)-releasing alkyl chain modified poly(amidoamine) (PAMAM) dendrimers of various sizes (i.e., generations). Generation 1 (G1) through generation 4 (G4) dendrimers were modified with either short (i.e., butyl) or medium (i.e., hexyl) alkyl chains via a ring-opening reaction. The resulting secondary amines were subsequently modified with N-diazeniumdiolate NO donors to establish NO payloads of ∼1.0 μmol/mg. The bactericidal efficacy of these dendrimers was evaluated against Gram-negative and Gram-positive biofilms, including antibiotic-resistant strains. The anti-biofilm action of the dendrimer biocides was found to be dependent on dendrimer generation, bacterial Gram class, and alkyl chain length, with the most effective biofilm eradication occurring when antibacterial agents were capable of efficient biofilm infiltration. The addition of NO release markedly enhanced anti-biofilm activity of dendrimers incapable of effective biofilm penetration. PMID:25873449

  1. Antifungal activity of alkyl gallates against plant pathogenic fungi.

    PubMed

    Ito, Shinsaku; Nakagawa, Yasutaka; Yazawa, Satoru; Sasaki, Yasuyuki; Yajima, Shunsuke

    2014-04-01

    The antifungal activity of alkyl gallates against plant pathogenic fungi was evaluated. All of the fungi tested in this study were susceptible to some alkyl gallates, and the effect of linear alkyl gallates against plant pathogenic fungi was similar to the previously reported effects against Gram-negative and Gram-positive bacteria. We found that branched alkyl gallates showed stronger activity than did linear alkyl gallates with similar logP values. In addition, the antifungal activity of alkyl gallates was correlated with gallate-induced inhibition of the activity of mitochondrial complex II. The antifungal activity of alkyl gallates likely originates, at least in part, from their ability to inhibit the membrane respiratory chain.

  2. Developmental Defects of Caenorhabditis elegans Lacking Branched-chain α-Ketoacid Dehydrogenase Are Mainly Caused by Monomethyl Branched-chain Fatty Acid Deficiency.

    PubMed

    Jia, Fan; Cui, Mingxue; Than, Minh T; Han, Min

    2016-02-01

    Branched-chain α-ketoacid dehydrogenase (BCKDH) catalyzes the critical step in the branched-chain amino acid (BCAA) catabolic pathway and has been the focus of extensive studies. Mutations in the complex disrupt many fundamental metabolic pathways and cause multiple human diseases including maple syrup urine disease (MSUD), autism, and other related neurological disorders. BCKDH may also be required for the synthesis of monomethyl branched-chain fatty acids (mmBCFAs) from BCAAs. The pathology of MSUD has been attributed mainly to BCAA accumulation, but the role of mmBCFA has not been evaluated. Here we show that disrupting BCKDH in Caenorhabditis elegans causes mmBCFA deficiency, in addition to BCAA accumulation. Worms with deficiency in BCKDH function manifest larval arrest and embryonic lethal phenotypes, and mmBCFA supplementation suppressed both without correcting BCAA levels. The majority of developmental defects caused by BCKDH deficiency may thus be attributed to lacking mmBCFAs in worms. Tissue-specific analysis shows that restoration of BCKDH function in multiple tissues can rescue the defects, but is especially effective in neurons. Taken together, we conclude that mmBCFA deficiency is largely responsible for the developmental defects in the worm and conceivably might also be a critical contributor to the pathology of human MSUD.

  3. Developmental Defects of Caenorhabditis elegans Lacking Branched-chain α-Ketoacid Dehydrogenase Are Mainly Caused by Monomethyl Branched-chain Fatty Acid Deficiency.

    PubMed

    Jia, Fan; Cui, Mingxue; Than, Minh T; Han, Min

    2016-02-01

    Branched-chain α-ketoacid dehydrogenase (BCKDH) catalyzes the critical step in the branched-chain amino acid (BCAA) catabolic pathway and has been the focus of extensive studies. Mutations in the complex disrupt many fundamental metabolic pathways and cause multiple human diseases including maple syrup urine disease (MSUD), autism, and other related neurological disorders. BCKDH may also be required for the synthesis of monomethyl branched-chain fatty acids (mmBCFAs) from BCAAs. The pathology of MSUD has been attributed mainly to BCAA accumulation, but the role of mmBCFA has not been evaluated. Here we show that disrupting BCKDH in Caenorhabditis elegans causes mmBCFA deficiency, in addition to BCAA accumulation. Worms with deficiency in BCKDH function manifest larval arrest and embryonic lethal phenotypes, and mmBCFA supplementation suppressed both without correcting BCAA levels. The majority of developmental defects caused by BCKDH deficiency may thus be attributed to lacking mmBCFAs in worms. Tissue-specific analysis shows that restoration of BCKDH function in multiple tissues can rescue the defects, but is especially effective in neurons. Taken together, we conclude that mmBCFA deficiency is largely responsible for the developmental defects in the worm and conceivably might also be a critical contributor to the pathology of human MSUD. PMID:26683372

  4. Molecular dynamics study of the effect of alkyl chain length on melting points of [CnMIM][PF6] ionic liquids

    SciTech Connect

    Zhang, Y; Maginn, EJ

    2014-01-01

    Based on molecular dynamics simulations, the melting points T-m of a series of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids [CnMIM][PF6] with n = 2, 4, 10, 12, and 14 were studied using the free energy-based pseudosupercritical path (PSCP) method. The experimental trend that the Tm decreases with increasing alkyl chain length for ILs with short alkyl chains and increases for the ones with long alkyl chains was correctly captured. Further analysis revealed that the different trends are the results of the balance between fusion enthalpy and fusion entropy. For the ILs with short alkyl chains (ethyl and butyl groups), fusion entropy plays the dominant role so that [C4MIM][PF6], which has a larger fusion entropy due to its higher liquid phase entropy has the lower melting temperature. As for the ILs with long alkyl chains, due to the enhanced van der Waals interactions brought about by the long non-polar alkyl chains, enthalpy becomes the deciding factor and the melting points increase when the alkyl chain goes from C10 to C14. While the melting points for [C2MIM][PF6] and [C4MIM][PF6] were quantitatively predicted and the trends for the long chain ILs were captured correctly, the absolute melting points for [C10MIM][PF6], [C12MIM][PF6] and [C14MIM][PF6] were systematically overestimated in the simulations. Three possible reasons for the overestimation were studied but all ruled out. Further simulation or experimental studies are needed to explain the difference.

  5. Molecular dynamics study of the effect of alkyl chain length on melting points of [CnMIM][PF6] ionic liquids.

    PubMed

    Zhang, Yong; Maginn, Edward J

    2014-07-14

    Based on molecular dynamics simulations, the melting points Tm of a series of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids [CnMIM][PF6] with n = 2, 4, 10, 12, and 14 were studied using the free energy-based pseudosupercritical path (PSCP) method. The experimental trend that the Tm decreases with increasing alkyl chain length for ILs with short alkyl chains and increases for the ones with long alkyl chains was correctly captured. Further analysis revealed that the different trends are the results of the balance between fusion enthalpy and fusion entropy. For the ILs with short alkyl chains (ethyl and butyl groups), fusion entropy plays the dominant role so that [C4MIM][PF6], which has a larger fusion entropy due to its higher liquid phase entropy has the lower melting temperature. As for the ILs with long alkyl chains, due to the enhanced van der Waals interactions brought about by the long non-polar alkyl chains, enthalpy becomes the deciding factor and the melting points increase when the alkyl chain goes from C10 to C14. While the melting points for [C2MIM][PF6] and [C4MIM][PF6] were quantitatively predicted and the trends for the long chain ILs were captured correctly, the absolute melting points for [C10MIM][PF6], [C12MIM][PF6] and [C14MIM][PF6] were systematically overestimated in the simulations. Three possible reasons for the overestimation were studied but all ruled out. Further simulation or experimental studies are needed to explain the difference.

  6. Oral branched-chain amino acids decrease whole-body proteolysis

    NASA Technical Reports Server (NTRS)

    Ferrando, A. A.; Williams, B. D.; Stuart, C. A.; Lane, H. W.; Wolfe, R. R.

    1995-01-01

    BACKGROUND: This study reports the effects of ingesting branched-chain amino acids (leucine, valine, and isoleucine) on protein metabolism in four men. METHODS: To calculate leg protein synthesis and breakdown, we used a new model that utilized the infusion of L-[ring-13C6]phenylalanine and the sampling of the leg arterial-venous difference and muscle biopsies. In addition, protein-bound enrichments provided for the direct calculation of muscle fractional synthetic rate. Four control subjects ingested an equivalent amount of essential amino acids (threonine, methionine, and histidine) to discern the effects of branched-chain amino acid nitrogen vs the effects of essential amino acid nitrogen. Each drink also included 50 g of carbohydrate. RESULTS: Consumption of the branched-chain and the essential amino acid solutions produced significant threefold and fourfold elevations in their respective arterial concentrations. Protein synthesis and breakdown were unaffected by branched-chain amino acids, but they increased by 43% (p < .05) and 36% (p < .03), respectively, in the group consuming the essential amino acids. However, net leg balance of phenylalanine was unchanged by either drink. Direct measurement of protein synthesis by tracer incorporation into muscle protein (fractional synthetic rate) revealed no changes within or between drinks. Whole-body phenylalanine flux was significantly suppressed by each solution but to a greater extent by the branched-chain amino acids (15% and 20%, respectively) (p < .001). CONCLUSIONS: These results suggest that branched-chain amino acid ingestion suppresses whole-body proteolysis in tissues other than skeletal muscle in normal men.

  7. Effect of alternative pathway therapy on branched chain amino acid metabolism in urea cycle disorder patients.

    PubMed

    Scaglia, Fernando; Carter, Susan; O'Brien, William E; Lee, Brendan

    2004-04-01

    Urea cycle disorders (UCDs) are a group of inborn errors of hepatic metabolism caused by the loss of enzymatic activities that mediate the transfer of nitrogen from ammonia to urea. These disorders often result in life-threatening hyperammonemia and hyperglutaminemia. A combination of sodium phenylbutyrate and sodium phenylacetate/benzoate is used in the clinical management of children with urea cycle defects as a glutamine trap, diverting nitrogen from urea synthesis to alternatives routes of excretion. We have observed that patients treated with these compounds have selective branched chain amino acid (BCAA) deficiency despite adequate dietary protein intake. However, the direct effect of alternative therapy on the steady state levels of plasma branched chain amino acids has not been well characterized. We have measured steady state plasma branched chain and other essential non-branched chain amino acids in control subjects, untreated ornithine transcarbamylase deficiency females and treated null activity urea cycle disorder patients in the fed steady state during the course of stable isotope studies. Steady-state leucine levels were noted to be significantly lower in treated urea cycle disorder patients when compared to either untreated ornithine transcarbamylase deficiency females or control subjects (P<0.0001). This effect was reproduced in control subjects who had depressed leucine levels when treated with sodium phenylacetate/benzoate (P<0.0001). Our studies suggest that this therapeutic modality has a substantial impact on the metabolism of branched chain amino acids in urea cycle disorder patients. These findings suggest that better titration of protein restriction could be achieved with branched chain amino acid supplementation in patients with UCDs who are on alternative route therapy.

  8. A roundabout approach to control morphological orientation and solar-cell performance by modulating side-chain branching position in benzodithiophene-based polymers.

    PubMed

    Lee, Kyu Cheol; Song, Seyeong; Lee, Junghoon; Kim, Dong Suk; Kim, Jin Young; Yang, Changduk

    2015-04-27

    To be meaningful to guide the rational design of novel high-performance conjugated semiconductors, we prepared three benzo[1,2-b:4,5-b']dithiophene (BDT)-based polymers by systematically moving the branching point of the alkyl chain. The effect of side-chain engineering was thoroughly investigated by a range of techniques. We demonstrate that a subtle change in the branching position in the BDT core can have a critical impact on polymer packing and preferential backbone orientation in thin films; copolymers made from BDT and thieno[3,4-c]pyrrole-4,6-dione units (TPD) adopt more of a face-on orientation as the branching point is shifted closer to the backbone, which can be correlated with a dramatic difference in solar-cells performance. The high short-circuit current density (11.6 mA cm(-2) ) for the copolymer with one carbon atom between the alkoxylated oxygen atom and the branching point results from its predominantly face-on orientation and smoother surface in thin films, which results in power conversion efficiencies as high as 4.56 %.

  9. Molecular pop-up toy: a molecular machine based on folding/unfolding motion of alkyl chains bound to a host.

    PubMed

    Ko, Young Ho; Hwang, Ilha; Kim, Hyunuk; Kim, Youngkook; Kim, Kimoon

    2015-01-01

    We have designed and synthesized a new type of molecular machine based on the folding/unfolding motion of an alkyl chain bound to a host, triggered by a redox stimulus. A guest molecule containing a viologen unit with a long alkyl chain 1(2+) and its one-electron reduced species 1 + . form very stable 1:1 host-guest complexes 2(2+) and 2 + ., respectively, with cucurbit[8]uril (CB[8]), where the long alkyl chain of the guests is in a folded conformation inside the host cavity. Upon addition of 2,6-dihydroxynaphthalene as an electron donor, the binary complex 2(2+) turns into a ternary complex 3(2+) through host-stabilized charge-transfer complex formation with the alkyl chain extended into the solution outside the host cavity. The ternary complex behaves like a molecular machine reminiscent of a pop-up toy, as it shows reversible folding/unfolding motion of the alkyl chain of the guest in response to a redox stimulus. For example, one-electron reduction of 3(2+) results in the rapid generation of the 2 + . complex, accompanied by a dramatic conformational change of the alkyl chain from an extended to a folded conformation, and the process can be reversed by oxidation.

  10. High orientation of long chain branched poly (lactic acid) with enhanced blood compatibility and bionic structure.

    PubMed

    Li, Zhengqiu; Ye, Lin; Zhao, Xiaowen; Coates, Phil; Caton-Rose, Fin; Martyn, Michasel

    2016-05-01

    Highly oriented poly (lactic acid) (PLA) with bionic microgrooves was fabricated through solid hot drawing technology for further improving the mechanical properties and blood biocompatibility of PLA. In order to enhance the melt strength and thus obtain high orientation degree, long chain branched PLA was prepared at first through a two-step ring-opening reaction during processing. Linear viscoelasticity combined with branch-on-branch model was used to predict probable compositions and chain topologies of the products, and it was found that the molecular weight of PLA increased and topological structures with star like chain with three arms and tree-like chain with two generations formed during reactive processing, and consequently draw ratio as high as1200% can be achieved during the subsequent hot stretching. With the increase of draw ratio, the tensile strength and orientation degree of PLA increased dramatically. Long chain branching and orientation could significantly enhance the blood compatibility of PLA by prolonging clotting time and decreasing platelet activation. Microgrooves can be observed on the surface of the oriented PLA which were similar to the intimal layer of blood vessel, and such bionic structure resulted from the formation of the oriented shish kebab-like crystals along the draw direction.

  11. Detection of Low Levels of Long-Chain Branching in Polyolefins

    NASA Astrophysics Data System (ADS)

    Karjala, T. P.; Sammler, R. L.; Mangnus, M. A.; Hazlitt, L. G.; Johnson, M. S.; Hagen, C. M.; Huang, J. W. L.; Reichek, K. N.

    2008-07-01

    Shear creep experiments have been applied to probe the zero-shear viscosity, η0, of molten undiluted polyolefin chains directly and precisely in a constant-stress rheometer at 190 °C. Such experiments when combined with precise measurements of the weight-average molecular weight, Mw (calibrated relative to linear chains of high-density polyethylene), are shown to provide a very sensitive approach to detect low levels (0.005 branches per 1000 carbons) of long-chain branching. This detection limit is shown with an extensive set of well-defined metallocene-based model materials to be insensitive to whether the molecular weight distribution is mono- or multi-modal, and/or to whether the molecular weight distribution breadth (Mw/Mn) rises to about ten. The approach is also shown to be insensitive to levels of short-chain branching found in poly(ethylene-co-butene) up to 12 wt% butene and poly(ethylene-co-hexene) up to 14 wt% hexene. In conclusion, this approach is a sensitive, robust, and rapid method to detect low levels of long-chain branching in polyolefin materials.

  12. Branched chain derivatives of alkyl oleates: tribological, rheological, oxidation, and low temperature properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report the evaluation of four previously prepared oleochemical alpha-hydroxy ethers (1-4) and soybean methyl esters (SME) against cloud point, pour point, oxidation stability, kinematic viscosity, specific gravity, lubricity, and surface tension. The ethers exhibit excellent cold flow behavior, ...

  13. Synthesis and Photophysical Properties of Soluble Low-Bandgap Thienothiophene Polymers with Various Alkyl Side-Chain Lengths

    SciTech Connect

    Bae, W. J.; Scilla, C.; Duzhko, V. V.; Jo, Jang; Coughlin, E. B.

    2011-05-27

    We report the facile synthesis and characterization of a class of thienothiophene polymers with various lengths of alkyl side chains. A series of 2-alkylthieno[3,4-b]thiophene monomers (Ttx) have been synthesized in a two-step protocol in an overall yield of 28–37%. Poly(2-alkylthieno[3,4-b]thiophenes) (PTtx, alkyl: pentyl, hexyl, heptyl, octyl, and tridecyl) were synthesized by oxidative polymerization with FeCl₃ or via Grignard metathesis (GRIM) polymerization methods. The polymers are readily soluble in common organic solvents. The polymers synthesized by GRIM polymerization method (PTtx-G) have narrower molecular weight distribution (Ð) with lower molecular weight (Mn) than those synthesized by oxidative polymerization (PTtx-O). The band structures of the polymers with various lengths of alkyl side chains were investigated by UV–vis spectroscopy, cyclic voltammetry, and ultraviolet photoelectron spectroscopy. These low-bandgap polymers are good candidates for organic transistors, organic light-emitting diodes, and organic photovoltaic cells.

  14. Surface active molecules: preparation and properties of long chain n-acyl-l-alpha-amino-omega-guanidine alkyl acid derivatives.

    PubMed

    Infante, R; Dominguez, J G; Erra, P; Julia, R; Prats, M

    1984-12-01

    Synopsis A new route for the synthesis of long chain N(alpha)-acyl-l-alpha-amino-omega-guamdine alkyl acid derivatives, with cationic or amphoteric character has been established. The general formula of these compounds is shown below. A physico-chemical and antimicrobial study of these products as a function of the alkyl ester or sodium salt (R), the straight chain length of the fatty acid residue (x) and the number of carbons between the omega-guanidine and omega-carboxyl group (n) has been investigated. The water solubility, surface tension, critical micelle concentration (c.m.c.) and minimum inhibitory concentration (MIC) against Gram-positive and Gram-negative bacteria (including Pseudomonas) has been determined. Dicyclohexylcarbodiimide has been used to condense fatty acids and alpha-amino-omega-guanidine alkyl acids. In these conditions protection of the omega-guanidine group is not necessary. The main characteristic of this synthetic procedure is the use of very mild experimental conditions (temperature, pH) to form the amide linkage which leads to pure optical compounds in high yield in the absence of electrolytes. The results show that some structural modifications, particularly the protection of the carboxyl group, promote variations of the surfactant and antimicrobial properties. Only those molecules with the blocked carboxyl group (cationic molecules, where R = Me, Et or Pr) showed a good surfactant and antimicrobial activity. When the carboxyl group was unprotected (amphoteric molecules, where R = Na(+)) the resulting compounds were inactive.

  15. Searching for low percolation thresholds within amphiphilic polymer membranes: The effect of side chain branching

    SciTech Connect

    Dorenbos, G.

    2015-06-14

    Percolation thresholds for solvent diffusion within hydrated model polymeric membranes are derived from dissipative particle dynamics in combination with Monte Carlo (MC) tracer diffusion calculations. The polymer backbones are composed of hydrophobic A beads to which at regular intervals Y-shaped side chains are attached. Each side chain is composed of eight A beads and contains two identical branches that are each terminated with a pendant hydrophilic C bead. Four types of side chains are considered for which the two branches (each represented as [C], [AC], [AAC], or [AAAC]) are splitting off from the 8th, 6th, 4th, or 2nd A bead, respectively. Water diffusion through the phase separated water containing pore networks is deduced from MC tracer diffusion calculations. The percolation threshold for the architectures containing the [C] and [AC] branches is at a water volume fraction of ∼0.07 and 0.08, respectively. These are much lower than those derived earlier for linear architectures of various side chain length and side chain distributions. Control of side chain architecture is thus a very interesting design parameter to decrease the percolation threshold for solvent and proton transports within flexible amphiphilic polymer membranes.

  16. Searching for low percolation thresholds within amphiphilic polymer membranes: The effect of side chain branching

    NASA Astrophysics Data System (ADS)

    Dorenbos, G.

    2015-06-01

    Percolation thresholds for solvent diffusion within hydrated model polymeric membranes are derived from dissipative particle dynamics in combination with Monte Carlo (MC) tracer diffusion calculations. The polymer backbones are composed of hydrophobic A beads to which at regular intervals Y-shaped side chains are attached. Each side chain is composed of eight A beads and contains two identical branches that are each terminated with a pendant hydrophilic C bead. Four types of side chains are considered for which the two branches (each represented as [C], [AC], [AAC], or [AAAC]) are splitting off from the 8th, 6th, 4th, or 2nd A bead, respectively. Water diffusion through the phase separated water containing pore networks is deduced from MC tracer diffusion calculations. The percolation threshold for the architectures containing the [C] and [AC] branches is at a water volume fraction of ˜0.07 and 0.08, respectively. These are much lower than those derived earlier for linear architectures of various side chain length and side chain distributions. Control of side chain architecture is thus a very interesting design parameter to decrease the percolation threshold for solvent and proton transports within flexible amphiphilic polymer membranes.

  17. The Characterization of Modified Starch Branching Enzymes: Toward the Control of Starch Chain-Length Distributions

    PubMed Central

    Li, Cheng; Wu, Alex Chi; Go, Rob Marc; Malouf, Jacob; Turner, Mark S.; Malde, Alpeshkumar K.; Mark, Alan E.; Gilbert, Robert G.

    2015-01-01

    Starch is a complex branched glucose polymer whose branch molecular weight distribution (the chain-length distribution, CLD) influences nutritionally important properties such as digestion rate. Chain-stopping in starch biosynthesis is by starch branching enzyme (SBE). Site-directed mutagenesis was used to modify SBEIIa from Zea mays (mSBEIIa) to produce mutants, each differing in a single conserved amino-acid residue. Products at different times from in vitro branching were debranched and the time evolution of the CLD measured by size-exclusion chromatography. The results confirm that Tyr352, Glu513, and Ser349 are important for mSBEIIa activity while Arg456 is important for determining the position at which the linear glucan is cut. The mutant mSBEIIa enzymes have different activities and suggest the length of the transferred chain can be varied by mutation. The work shows analysis of the molecular weight distribution can yield information regarding the enzyme branching sites useful for development of plants yielding starch with improved functionality. PMID:25874689

  18. Metformin inhibits Branched Chain Amino Acid (BCAA) derived ketoacidosis and promotes metabolic homeostasis in MSUD

    PubMed Central

    S. Sonnet, Davis; N. O’Leary, Monique; A. Gutierrez, Mark; M. Nguyen, Steven; Mateen, Samiha; Hsu, Yuehmei; P. Mitchell, Kylie; J. Lopez, Antonio; Vockley, Jerry; K. Kennedy, Brian; Ramanathan, Arvind

    2016-01-01

    Maple Syrup Urine Disease (MSUD) is an inherited disorder caused by the dysfunction in the branched chain keto-acid dehydrogenase (BCKDH) enzyme. This leads to buildup of branched-chain keto-acids (BCKA) and branched-chain amino acids (BCAA) in body fluids (e.g. keto-isocaproic acid from the BCAA leucine), leading to numerous clinical features including a less understood skeletal muscle dysfunction in patients. KIC is an inhibitor of mitochondrial function at disease relevant concentrations. A murine model of intermediate MSUD (iMSUD) shows significant skeletal muscle dysfunction as by judged decreased muscle fiber diameter. MSUD is an orphan disease with a need for novel drug interventions. Here using a 96-well plate (liquid chromatography- mass spectrometry (LC-MS) based drug-screening platform we show that Metformin, a widely used anti-diabetic drug, reduces levels of KIC in patient-derived fibroblasts by 20–50%. This Metformin-mediated effect was conserved in vivo; Metformin-treatment significantly reduced levels of KIC in the muscle (by 69%) and serum (by 56%) isolated from iMSUD mice, and restored levels of mitochondrial metabolites (e.g. AMP and other TCA). The drug also decreased the expression of mitochondrial branched chain amino transferase (BCAT) which produces KIC in skeletal muscle. This suggests that Metformin can restore skeletal muscle homeostasis in MSUD by decreasing mitochondrial KIC production. PMID:27373929

  19. Enzymology of the branched-chain amino acid oxidation disorders: the valine pathway.

    PubMed

    Wanders, Ronald J A; Duran, Marinus; Loupatty, Ference J

    2012-01-01

    Valine is one of the three branched-chain amino acids which undergoes oxidation within mitochondria. In this paper, we describe the current state of knowledge with respect to the enzymology of the valine oxidation pathway and the different disorders affecting oxidation.

  20. Genetic and physiological analysis of branched-chain alcohols and isoamyl acetate production in Saccharomyces cerevisiae.

    PubMed

    Yoshimoto, H; Fukushige, T; Yonezawa, T; Sone, H

    2002-08-01

    Branched-chain alcohols, such as isoamyl alcohol and isobutanol, and isoamyl acetate are important flavor components of yeast-fermented alcoholic beverages. Analysis of a null mutant of the BAT2 gene encoding cytosolic branched-chain amino acid aminotransferase, and a transformant with multi-copy plasmids containing the BAT2 gene showed that the BAT2 gene product plays an important role in the production of branched-chain alcohols and isoamyl acetate. Fermentation tests using the bat2 null mutant transformed with multi-copy plasmids carrying the ATF1 gene, which encodes alcohol acetyltransferase, indicated that modified expression of BAT2 and ATF1 genes could significantly alter the proportion of branched-chain alcohols and isoamyl acetate synthesized. Furthermore, fermentation tests using different ratios of nitrogen source and RNA blot analyses demonstrated that transcription of L-leucine biosynthetic ( LEU) and BAT genes is co-regulated by nitrogen source, that production of isoamyl alcohol depends on this transcription, and that ATF transcription increased with increased concentrations of nitrogen source. Our data suggest that changes in isoamyl alcohol production by nitrogen source are due to transcriptional co-regulation of LEU and BAT genes, and that production of isoamyl acetate is dependent on isoamyl alcohol production and ATF transcription. PMID:12172617

  1. Comparative effects of oral aromatic and branched-chain amino acids on urine calcium and excretion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aromatic amino acids (AAAs) bind to the calcium sensor receptor (CaR) but branched-chain amino acids (B-CAAs) do not; by binding to this receptor, AAAs have an increased potential to affect calcium homeostasis. This study was conducted to determine and compare the effects of AAAs and B-CAAs on calci...

  2. Use of branched chain amino acids for treating hepatic encephalopathy: clinical experiences.

    PubMed Central

    Rossi Fanelli, F; Cangiano, C; Capocaccia, L; Cascino, A; Ceci, F; Muscaritoli, M; Giunchi, G

    1986-01-01

    The efficacy of branched chain amino acids in two consecutive clinical studies in patients with severe hepatic encephalopathy was tested. In the preliminary uncontrolled study 19 patients with grade 3-4 hepatic encephalopathy were given an intravenous solution containing leucine 11 g/l, isoleucine 9 g/l, and valine 8.4 g/l in 20% dextrose. A complete recovery of mental state was obtained in all patients in a mean time of 20.5 hours. In a subsequent controlled study 40 patients with grade 3-4 hepatic encephalopathy were randomly assigned to receive intravenous branched chain amino acid in 20% dextrose (group A) or oral lactulose (group B). Twelve patients (70.6%) in group A and eight (47%) in group B regained consciousness in a mean time of 27.6 and 31.5 hours, respectively. The difference in the recovery rate between the two groups, although evident, was not significant. Intravenous branched chain amino acids are thus at least as effective as lactulose in reversing hepatic coma. These data argue strongly in favour of a therapeutic effect of branched chain amino acids in the treatment of hepatic encephalopathy in patients with chronic liver failure. PMID:3539709

  3. Metformin inhibits Branched Chain Amino Acid (BCAA) derived ketoacidosis and promotes metabolic homeostasis in MSUD.

    PubMed

    S Sonnet, Davis; N O'Leary, Monique; A Gutierrez, Mark; M Nguyen, Steven; Mateen, Samiha; Hsu, Yuehmei; P Mitchell, Kylie; J Lopez, Antonio; Vockley, Jerry; K Kennedy, Brian; Ramanathan, Arvind

    2016-01-01

    Maple Syrup Urine Disease (MSUD) is an inherited disorder caused by the dysfunction in the branched chain keto-acid dehydrogenase (BCKDH) enzyme. This leads to buildup of branched-chain keto-acids (BCKA) and branched-chain amino acids (BCAA) in body fluids (e.g. keto-isocaproic acid from the BCAA leucine), leading to numerous clinical features including a less understood skeletal muscle dysfunction in patients. KIC is an inhibitor of mitochondrial function at disease relevant concentrations. A murine model of intermediate MSUD (iMSUD) shows significant skeletal muscle dysfunction as by judged decreased muscle fiber diameter. MSUD is an orphan disease with a need for novel drug interventions. Here using a 96-well plate (liquid chromatography- mass spectrometry (LC-MS) based drug-screening platform we show that Metformin, a widely used anti-diabetic drug, reduces levels of KIC in patient-derived fibroblasts by 20-50%. This Metformin-mediated effect was conserved in vivo; Metformin-treatment significantly reduced levels of KIC in the muscle (by 69%) and serum (by 56%) isolated from iMSUD mice, and restored levels of mitochondrial metabolites (e.g. AMP and other TCA). The drug also decreased the expression of mitochondrial branched chain amino transferase (BCAT) which produces KIC in skeletal muscle. This suggests that Metformin can restore skeletal muscle homeostasis in MSUD by decreasing mitochondrial KIC production. PMID:27373929

  4. Branched-chain amino acids in metabolic signaling and insulin resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Branched-chain amino acids (BCAAs) are important directly- and indirectly-acting nutrient signals. Frequently, their actions have been reported to be anti-obesity in nature, especially in rodent models. Yet, circulating BCAAs tend to be elevated in obesity, and even associated with poorer metaboli...

  5. The cytosolic branched-chain aminotransferases of Arabidopsis thaliana influence methionine supply, salvage and glucosinolate metabolism.

    PubMed

    Lächler, Kurt; Imhof, Janet; Reichelt, Michael; Gershenzon, Jonathan; Binder, Stefan

    2015-05-01

    Arabidopsis thaliana possesses six branched-chain aminotransferases (BCAT1-6). Previous studies revealed that some members of this protein family are involved in the biosynthesis of branched-chain amino acids and/or in the Met chain elongation pathway, the initial steps towards the biosynthesis of Met-derived glucosinolates. We now analyzed branched-chain aminotransferase 6 (BCAT6). In vivo GFP-tagging experiments strongly suggest this enzyme to be localized to the cytosol. Substrate specificity assays performed with recombinant enzyme revealed that BCAT6 transaminates Val, Leu and Ile as well as the corresponding 2-oxo acids but also transaminates Met and its cognate ketoacid 4-methyl-2-oxobutanoate. We established single (bcat6-1), double (bcat4-2/bcat6-1) and triple (bcat3-1/bcat4-2/bcat6-1) mutants involving BCAT6 with the latter exhibiting a clear macroscopic phenotype with smaller plants and abnormal leaf morphology. Metabolite profiling of these mutants demonstrated that BCAT6 can contribute to Met chain elongation with the triple mutant line lacking BCAT3, 4 and 6 showing a dramatic reduction of Met-derived glucosinolate species down to 32 and 14% of wild-type levels in plant foliage and seeds, respectively. This drop in glucosinolate levels is accompanied by a 46-fold increase of free Met, demonstrating the important role of the three branched-chain aminotransferases in converting Met to its 2-oxo acid for glucosinolate chain elongation. In addition, we determined the relative amounts of 5'-deoxy-5'-methylthioadenosine, an intermediate of the Met recycling pathway. This metabolite accumulated to relative high amounts in the absence of the cytosolic BCAT4 and BCAT6, suggesting that cytosolic Met salvage also contributes to the biosynthesis of glucosinolates. PMID:25851613

  6. Self-Spreading of Lipid Bilayer on a Hydrophobic Surface Made by Self-Assembled Monolayer with Short Alkyl Chain.

    PubMed

    Omori, Yuya; Sakaue, Hiroyuki; Takahagi, Takayuki; Suzuki, Hitoshi

    2016-04-01

    Behaviors of self-spreading of lipid bilayer membrane on a glass surface modified with self-assembled monolayer (SAM) with short alkyl chain were observed with fluorescence microscopy. Hydrophobic surface made by SAM was found to hamper the self-spreading phenomenon but the lipid bilayer spread on a hydrophilic one where SAM was decomposed by oxidation. On a binary surface having a hydrophobic region and a hydrophilic one, the lipid bilayer spread on the hydrophilic region but it stopped at the boundary of the hydrophobic region.

  7. Surface Segregation and Bulk Thermodynamics in Blends of Long-Branched and Linear Chains

    NASA Astrophysics Data System (ADS)

    Martter, T. D.; Foster, M. D.; Xu, S.; Yoo, T.; Quirk, R. P.; Ohno, K.; Haddleton, D. M.; Hawker, C.; Majkrzak, C.; Butler, P.

    2001-03-01

    We have investigated the effect of regular long chain branching on bulk thermodynamics and surface segregation in blends of linear and branched polymers. Polystyrene and low vinyl content polybutadiene polymerized anionically have both been studied. The nonlocal thermodynamic interaction between the chains in the bulk can be characterized by a segment-segment interaction parameter, chi, measured using Small Angle Neutron Scattering. While chi is found to increase monotonically with the number of arms in the star for PS blends, this is not true for PB blends. In the case of the PB blends, isotopic effects play a more important role in determining the segregation behavior than in the case of the PS blends. Some experiments have also been performed to probe the effect of core chemistry on the bulk and surface behavior. Changing the type of long-branched component from star-branched to comb-branched, while the number of arms is kept constant, impacts both the bulk interaction and surface segregation. Acknowledgements: Collaborators were G. Lizzaraga, J. Hwang, C.C. Greenberg, S. Corona-Galvan, and E. Cloutet (Institute of Polymer Science at The University of Akron) and J.D. Demaree (Army Research Lab, AMSRL-WM-ME, APG, MD 21005).

  8. Alkyl Chain Length Dependence of the Dynamics and Structure in the Ionic Regions of Room-Temperature Ionic Liquids.

    PubMed

    Tamimi, Amr; Bailey, Heather E; Fayer, Michael D

    2016-08-01

    The dynamics of four 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide room-temperature ionic liquids (RTILs) with carbon chain lengths of 2, 4, 6, and 10 were studied by measuring the orientational and spectral diffusion dynamics of the vibrational probe SeCN(-). Vibrational absorption spectra, two-dimensional infrared (2D IR), and polarization-selective pump-probe (PSPP) experiments were performed on the CN stretch. In addition, optical heterodyne-detected optical Kerr effect (OHD-OKE) experiments were performed on the bulk liquids. The PSPP experiments yielded triexponential anisotropy decays, which were analyzed with the wobbling-in-a-cone model. The slowest decay, the complete orientational randomization, slows with increasing chain length in a hydrodynamic trend consistent with the increasing viscosity. The shortest time scale wobbling motions are insensitive to chain length, while the intermediate time scale wobbling slows mildly as the chain length increases. The 2D IR spectra measured in parallel (⟨XXXX⟩) and perpendicular (⟨XXYY⟩) polarization configurations gave different decays, showing that reorientation-induced spectral diffusion (RISD) contributes to the dynamics. The spectral diffusion caused by the RTIL structural fluctuations was obtained by removing the RISD contributions. The faster structural fluctuations are relatively insensitive to chain length. The slowest structural fluctuations slow substantially when going from Emim (2 carbon chain) to Bmim (4 carbon chain) and slow further, but more gradually, as the chain length is increased. It was shown previously that K(+) causes local ion clustering in the Emim RTIL. The K(+) effect increases with increasing chain length. The OHD-OKE measured complete structural randomization times slow substantially with increasing chain length and are much slower than the dynamics experienced by the SeCN(-) located in the ionic regions of the RTILs.

  9. Shear-induced enhancements of crystallization kinetics and morphological transformation for long chain branched polylactides with different branching degrees

    PubMed Central

    Wang, Junyang; Bai, Jing; Zhang, Yaqiong; Fang, Huagao; Wang, Zhigang

    2016-01-01

    The effects of long chain branching (LCB) degree on the shear-induced isothermal crystallization kinetics of a series of LCB polylactides (LCB PLAs) have been investigated by using rotational rheometer, polarized optical microscopy (POM) and scanning electron microscopy (SEM). Dynamic viscoelastic properties obtained by small-amplitude oscillatory shear (SAOS) tests indicate that LCB PLAs show more broadened relaxation time spectra with increasing LCB degree. Upon a pre-shear at the shear rate of 1 s−1 LCB PLAs show much faster crystallization kinetics than linear PLA and the crystallization kinetics is enhanced with increasing LCB degree. By modeling the system as a suspension the quantitative evaluation of nucleation density can be derived from rheological experiments. The nucleation density is greatly enhanced with increasing LCB degree and a saturation in shear time is observed. Crystalline morphologies for LCB PLAs observed by POM and SEM demonstrate the enhancement of nucleation density with increasing LCB degree and a transformation from spherulitic to orientated crystalline morphologies. The observation can be ascribed to longer relaxation time of the longest macromolecular chains and broadened, complex relaxation behaviors due to the introduction of LCB into PLA, which is essential in stabilizing the orientated crystal nuclei after pre-shear. PMID:27246803

  10. Shear-induced enhancements of crystallization kinetics and morphological transformation for long chain branched polylactides with different branching degrees

    NASA Astrophysics Data System (ADS)

    Wang, Junyang; Bai, Jing; Zhang, Yaqiong; Fang, Huagao; Wang, Zhigang

    2016-06-01

    The effects of long chain branching (LCB) degree on the shear-induced isothermal crystallization kinetics of a series of LCB polylactides (LCB PLAs) have been investigated by using rotational rheometer, polarized optical microscopy (POM) and scanning electron microscopy (SEM). Dynamic viscoelastic properties obtained by small-amplitude oscillatory shear (SAOS) tests indicate that LCB PLAs show more broadened relaxation time spectra with increasing LCB degree. Upon a pre-shear at the shear rate of 1 s‑1 LCB PLAs show much faster crystallization kinetics than linear PLA and the crystallization kinetics is enhanced with increasing LCB degree. By modeling the system as a suspension the quantitative evaluation of nucleation density can be derived from rheological experiments. The nucleation density is greatly enhanced with increasing LCB degree and a saturation in shear time is observed. Crystalline morphologies for LCB PLAs observed by POM and SEM demonstrate the enhancement of nucleation density with increasing LCB degree and a transformation from spherulitic to orientated crystalline morphologies. The observation can be ascribed to longer relaxation time of the longest macromolecular chains and broadened, complex relaxation behaviors due to the introduction of LCB into PLA, which is essential in stabilizing the orientated crystal nuclei after pre-shear.

  11. Fluoroalkyl and Alkyl Chains Have Similar Hydrophobicities in Binding to the “Hydrophobic Wall” of Carbonic Anhydrase

    SciTech Connect

    J Mecinovic; P Snyder; K Mirica; S Bai; E Mack; R Kwant; D Moustakas; A Heroux; G Whitesides

    2011-12-31

    The hydrophobic effect, the free-energetically favorable association of nonpolar solutes in water, makes a dominant contribution to binding of many systems of ligands and proteins. The objective of this study was to examine the hydrophobic effect in biomolecular recognition using two chemically different but structurally similar hydrophobic groups, aliphatic hydrocarbons and aliphatic fluorocarbons, and to determine whether the hydrophobicity of the two groups could be distinguished by thermodynamic and biostructural analysis. This paper uses isothermal titration calorimetry (ITC) to examine the thermodynamics of binding of benzenesulfonamides substituted in the para position with alkyl and fluoroalkyl chains (H{sub 2}NSO{sub 2}C{sub 6}H{sub 4}-CONHCH{sub 2}(CX{sub 2}){sub n}CX{sub 3}, n = 0-4, X = H, F) to human carbonic anhydrase II (HCA II). Both alkyl and fluoroalkyl substituents contribute favorably to the enthalpy and the entropy of binding; these contributions increase as the length of chain of the hydrophobic substituent increases. Crystallography of the protein-ligand complexes indicates that the benzenesulfonamide groups of all ligands examined bind with similar geometry, that the tail groups associate with the hydrophobic wall of HCA II (which is made up of the side chains of residues Phe131, Val135, Pro202, and Leu204), and that the structure of the protein is indistinguishable for all but one of the complexes (the longest member of the fluoroalkyl series). Analysis of the thermodynamics of binding as a function of structure is compatible with the hypothesis that hydrophobic binding of both alkyl and fluoroalkyl chains to hydrophobic surface of carbonic anhydrase is due primarily to the release of nonoptimally hydrogen-bonded water molecules that hydrate the binding cavity (including the hydrophobic wall) of HCA II and to the release of water molecules that surround the hydrophobic chain of the ligands. This study defines the balance of enthalpic and

  12. Alkyl-chain-grafted hexagonal boron nitride nanoplatelets as oil-dispersible additives for friction and wear reduction.

    PubMed

    Kumari, Sangita; Sharma, Om P; Gusain, Rashi; Mungse, Harshal P; Kukrety, Aruna; Kumar, Niranjan; Sugimura, Hiroyuki; Khatri, Om P

    2015-02-18

    Hexagonal boron nitride (h-BN), an isoelectric analogous to graphene multilayer, can easily shear at the contact interfaces and exhibits excellent mechanical strength, higher thermal stability, and resistance toward oxidation, which makes it a promising material for potential lubricant applications. However, the poor dispersibility of h-BN in lube base oil has been a major obstacle. Herein, h-BN powder was exfoliated into h-BN nanoplatelets (h-BNNPs), and then long alkyl chains were chemically grafted, targeting the basal plane defect and edge sites of h-BNNPs. The chemical and structural features of octadecyltriethoxysilane-functionalized h-BNNPs (h-BNNPs-ODTES) were studied by FTIR, XPS, XRD, HRTEM, and TGA analyses. The h-BNNPs-ODTES exhibit long-term dispersion stability in synthetic polyol ester lube base oil because of van der Waals interaction between the octadecyl chains of h-BNNPs-ODTES and alkyl functionalities of polyol ester. Micro- and macrotribology results showed that h-BNNPs-ODTES, as an additive to synthetic polyol ester, significantly reduced both the friction and wear of steel disks. Elemental mapping of the worn area explicitly demonstrates the transfer of h-BNNPs-ODTES on the contact interfaces. Furthermore, insight into the lubrication mechanism for reduction in both friction and wear is deduced based on the experimental results. PMID:25625695

  13. Alkyl-chain-grafted hexagonal boron nitride nanoplatelets as oil-dispersible additives for friction and wear reduction.

    PubMed

    Kumari, Sangita; Sharma, Om P; Gusain, Rashi; Mungse, Harshal P; Kukrety, Aruna; Kumar, Niranjan; Sugimura, Hiroyuki; Khatri, Om P

    2015-02-18

    Hexagonal boron nitride (h-BN), an isoelectric analogous to graphene multilayer, can easily shear at the contact interfaces and exhibits excellent mechanical strength, higher thermal stability, and resistance toward oxidation, which makes it a promising material for potential lubricant applications. However, the poor dispersibility of h-BN in lube base oil has been a major obstacle. Herein, h-BN powder was exfoliated into h-BN nanoplatelets (h-BNNPs), and then long alkyl chains were chemically grafted, targeting the basal plane defect and edge sites of h-BNNPs. The chemical and structural features of octadecyltriethoxysilane-functionalized h-BNNPs (h-BNNPs-ODTES) were studied by FTIR, XPS, XRD, HRTEM, and TGA analyses. The h-BNNPs-ODTES exhibit long-term dispersion stability in synthetic polyol ester lube base oil because of van der Waals interaction between the octadecyl chains of h-BNNPs-ODTES and alkyl functionalities of polyol ester. Micro- and macrotribology results showed that h-BNNPs-ODTES, as an additive to synthetic polyol ester, significantly reduced both the friction and wear of steel disks. Elemental mapping of the worn area explicitly demonstrates the transfer of h-BNNPs-ODTES on the contact interfaces. Furthermore, insight into the lubrication mechanism for reduction in both friction and wear is deduced based on the experimental results.

  14. Anti-j: human cold agglutinins recognizing linear (i) and branched (I) type 2 chains.

    PubMed

    Roelcke, D; Kreft, H; Hack, H; Stevenson, F K

    1994-01-01

    Two IgM lambda cold agglutinins (CAs) reacted with protease- and sialidase-resistant antigens expressed in equal strength on human adult (I), newborn (i), i adult, rabbit (I) and rhesus monkey (i) erythrocytes. The antibodies were inhibited by the linear type 2 sequence lacto-N-neotetraose and the branched type 2 sequence lacto-N-neohexaose. Endo-beta-galactosidase treatment of red cells, which splits type 2 chains from the surface, abolished CA reactivity. The CAs expressed the idiotype recognized by the anti-idiotype 9G4 specific for anti-I and anti-i CAs. The data suggest that the two CAs recognize linear (i) as well as branched (I) type 2 chains. It is proposed to term these CAs anti-j.

  15. Branched-Chain Aminotransferases Control TORC1 Signaling in Saccharomyces cerevisiae

    PubMed Central

    Kingsbury, Joanne M.; Sen, Neelam D.; Cardenas, Maria E.

    2015-01-01

    The conserved target of rapamycin complex 1 (TORC1) integrates nutrient signals to orchestrate cell growth and proliferation. Leucine availability is conveyed to control TORC1 activity via the leu-tRNA synthetase/EGOC-GTPase module in yeast and mammals, but the mechanisms sensing leucine remain only partially understood. We show here that both leucine and its α-ketoacid metabolite, α-ketoisocaproate, effectively activate the yeast TORC1 kinase via both EGOC GTPase-dependent and -independent mechanisms. Leucine and α-ketoisocaproate are interconverted by ubiquitous branched-chain aminotransferases (BCAT), which in yeast are represented by the mitochondrial and cytosolic enzymes Bat1 and Bat2, respectively. BCAT yeast mutants exhibit severely compromised TORC1 activity, which is partially restored by expression of Bat1 active site mutants, implicating both catalytic and structural roles of BCATs in TORC1 control. We find that Bat1 interacts with branched-chain amino acid metabolic enzymes and, in a leucine-dependent fashion, with the tricarboxylic acid (TCA)-cycle enzyme aconitase. BCAT mutation perturbed TCA-cycle intermediate levels, consistent with a TCA-cycle block, and resulted in low ATP levels, activation of AMPK, and TORC1 inhibition. We propose the biosynthetic capacity of BCAT and its role in forming multicomplex metabolons connecting branched-chain amino acids and TCA-cycle metabolism governs TCA-cycle flux to activate TORC1 signaling. Because mammalian mitochondrial BCAT is known to form a supramolecular branched-chain α-keto acid dehydrogenase enzyme complex that links leucine metabolism to the TCA-cycle, these findings establish a precedent for understanding TORC1 signaling in mammals. PMID:26659116

  16. Behavioral responses in rats submitted to chronic administration of branched-chain amino acids.

    PubMed

    Scaini, Giselli; Jeremias, Gabriela C; Furlanetto, Camila B; Dominguini, Diogo; Comim, Clarissa M; Quevedo, João; Schuck, Patrícia F; Ferreira, Gustavo C; Streck, Emilio L

    2014-01-01

    Maple syrup urine disease (MSUD) is an inborn metabolism error caused by a deficiency of branched-chain α-keto acid dehydrogenase complex activity. This blockage leads to an accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine, and valine, as well as their corresponding α-keto and α-hydroxy acids. Previous reports suggest that MSUD patients are at high risk for chronic neuropsychiatric problems. Therefore, in this study, we assessed variables that suggest depressive-like symptoms (anhedonia as measured by sucrose intake, immobility during the forced swimming test and body and adrenal gland weight) in rats submitted to chronic administration of BCAA during development. Furthermore, we determined if these parameters were sensitive to imipramine and N-acetylcysteine/deferoxamine (NAC/DFX). Our results demonstrated that animals subjected to chronic administration of branched-chain amino acids showed a decrease in sucrose intake without significant changes in body weight. We also observed an increase in adrenal gland weight and immobility time during the forced swimming test. However, treatment with imipramine and NAC/DFX reversed these changes in the behavioral tasks. In conclusion, this study demonstrates a link between MSUD and depression in rats. Moreover, this investigation reveals that the antidepressant action of NAC/DFX and imipramine might be associated with their capability to maintain pro-/anti-oxidative homeostasis. PMID:24214724

  17. Ether- versus ester-linked phospholipid bilayers containing either linear or branched apolar chains.

    PubMed

    Balleza, Daniel; Garcia-Arribas, Aritz B; Sot, Jesús; Ruiz-Mirazo, Kepa; Goñi, Félix M

    2014-09-16

    We studied the properties of bilayers formed by ether-and ester-containing phospholipids, whose hydrocarbon chains can be either linear or branched, using sn-1,2 dipalmitoyl, dihexadecyl, diphytanoyl, and diphytanyl phosphatidylcholines (DPPC, DHPC, DPhoPC, and DPhPC, respectively) either pure or in binary mixtures. Differential scanning calorimetry and confocal fluorescence microscopy of giant unilamellar vesicles concurred in showing that equimolar mixtures of linear and branched lipids gave rise to gel/fluid phase coexistence at room temperature. Mixtures containing DHPC evolved in time (0.5 h) from initial reticulated domains to extended solid ones when an equilibrium was achieved. The nanomechanical properties of supported planar bilayers formed by each of the four lipids studied by atomic force microscopy revealed average breakdown forces Fb decreasing in the order DHPC ≥ DPPC > DPhoPC > DPhPC. Moreover, except for DPPC, two different Fb values were found for each lipid. Atomic force microscopy imaging of DHPC was peculiar in showing two coexisting phases of different heights, probably corresponding to an interdigitated gel phase that gradually transformed, over a period of 0.5 h, into a regular tilted gel phase. Permeability to nonelectrolytes showed that linear-chain phospholipids allowed a higher rate of solute + water diffusion than branched-chain phospholipids, yet the former supported a smaller extent of swelling of the corresponding vesicles. Ether or ester bonds appeared to have only a minor effect on permeability.

  18. Ether- versus Ester-Linked Phospholipid Bilayers Containing either Linear or Branched Apolar Chains

    PubMed Central

    Balleza, Daniel; Garcia-Arribas, Aritz B.; Sot, Jesús; Ruiz-Mirazo, Kepa; Goñi, Félix M.

    2014-01-01

    We studied the properties of bilayers formed by ether-and ester-containing phospholipids, whose hydrocarbon chains can be either linear or branched, using sn-1,2 dipalmitoyl, dihexadecyl, diphytanoyl, and diphytanyl phosphatidylcholines (DPPC, DHPC, DPhoPC, and DPhPC, respectively) either pure or in binary mixtures. Differential scanning calorimetry and confocal fluorescence microscopy of giant unilamellar vesicles concurred in showing that equimolar mixtures of linear and branched lipids gave rise to gel/fluid phase coexistence at room temperature. Mixtures containing DHPC evolved in time (0.5 h) from initial reticulated domains to extended solid ones when an equilibrium was achieved. The nanomechanical properties of supported planar bilayers formed by each of the four lipids studied by atomic force microscopy revealed average breakdown forces Fb decreasing in the order DHPC ≥ DPPC > DPhoPC >> DPhPC. Moreover, except for DPPC, two different Fb values were found for each lipid. Atomic force microscopy imaging of DHPC was peculiar in showing two coexisting phases of different heights, probably corresponding to an interdigitated gel phase that gradually transformed, over a period of 0.5 h, into a regular tilted gel phase. Permeability to nonelectrolytes showed that linear-chain phospholipids allowed a higher rate of solute + water diffusion than branched-chain phospholipids, yet the former supported a smaller extent of swelling of the corresponding vesicles. Ether or ester bonds appeared to have only a minor effect on permeability. PMID:25229144

  19. Drosophila miR-277 controls branched-chain amino acid catabolism and affects lifespan

    PubMed Central

    Esslinger, Stephanie Maria; Schwalb, Björn; Helfer, Stephanie; Michalik, Katharina Maria; Witte, Heidi; Maier, Kerstin C.; Martin, Dietmar; Michalke, Bernhard; Tresch, Achim; Cramer, Patrick; Förstemann, Klaus

    2013-01-01

    Development, growth and adult survival are coordinated with available metabolic resources, ascertaining that the organism responds appropriately to environmental conditions. MicroRNAs are short (21–23 nt) regulatory RNAs that confer specificity on the RNA-induced silencing complex (RISC) to inhibit a given set of mRNA targets. We profiled changes in miRNA expression during adult life in Drosophila melanogaster and determined that miR-277 is downregulated during adult life. Molecular analysis revealed that this miRNA controls branched-chain amino acid (BCAA) catabolism and as a result it can modulate the activity of the TOR kinase, a central growth regulator, in cultured cells. Metabolite analysis in cultured cells as well as flies suggests that the mechanistic basis may be an accumulation of branched-chain α-keto-acids (BCKA), rather than BCAAs, thus avoiding potentially detrimental consequences of increased branched chain amino acid levels on e.g., translational fidelity. Constitutive miR-277 expression shortens lifespan and is synthetically lethal with reduced insulin signaling, indicating that metabolic control underlies this phenotype. Transgenic inhibition with a miRNA sponge construct also shortens lifespan, in particular on protein-rich food. Thus, optimal metabolic adaptation appears to require tuning of cellular BCAA catabolism by miR-277. PMID:23669073

  20. Evolution of the biosynthesis of the branched-chain amino acids

    NASA Astrophysics Data System (ADS)

    Keefe, Anthony D.; Lazcano, Antonio; Miller, Stanley L.

    1995-06-01

    The origin of the biosynthetic pathways for the branched-chain amino acids cannot be understood in terms of the backwards development of the present acetolactate pathway because it contains unstable intermediates. We propose that the first biosynthesis of the branched-chain amino acids was by the reductive carboxylation of short branched chain fatty acids giving keto acids which were then transaminated. Similar reaction sequences mediated by nonspecific enzymes would produce serine and threonine from the abundant prebiotic compounds glycolic and lactic acids. The aromatic amino acids may also have first been synthesized in this way, e.g. tryptophan from indole acetic acid. The next step would have been the biosynthesis of leucine from α-ketoisovaleric acid. The acetolactate pathway developed subsequently. The first version of the Krebs cycle, which was used for amino acid biosynthesis, would have been assembled by making use of the reductive carboxylation and leucine biosynthesis enzymes, and completed with the development of a single new enzyme, succinate dehydrogenase. This evolutionary scheme suggests that there may be limitations to inferring the origins of metabolism by a simple back extrapolation of current pathways.

  1. Impaired adiponectin signaling contributes to disturbed catabolism of branched-chain amino acids in diabetic mice.

    PubMed

    Lian, Kun; Du, Chaosheng; Liu, Yi; Zhu, Di; Yan, Wenjun; Zhang, Haifeng; Hong, Zhibo; Liu, Peilin; Zhang, Lijian; Pei, Haifeng; Zhang, Jinglong; Gao, Chao; Xin, Chao; Cheng, Hexiang; Xiong, Lize; Tao, Ling

    2015-01-01

    The branched-chain amino acids (BCAA) accumulated in type 2 diabetes are independent contributors to insulin resistance. The activity of branched-chain α-keto acid dehydrogenase (BCKD) complex, rate-limiting enzyme in BCAA catabolism, is reduced in diabetic states, which contributes to elevated BCAA concentrations. However, the mechanisms underlying decreased BCKD activity remain poorly understood. Here, we demonstrate that mitochondrial phosphatase 2C (PP2Cm), a newly identified BCKD phosphatase that increases BCKD activity, was significantly downregulated in ob/ob and type 2 diabetic mice. Interestingly, in adiponectin (APN) knockout (APN(-/-)) mice fed with a high-fat diet (HD), PP2Cm expression and BCKD activity were significantly decreased, whereas BCKD kinase (BDK), which inhibits BCKD activity, was markedly increased. Concurrently, plasma BCAA and branched-chain α-keto acids (BCKA) were significantly elevated. APN treatment markedly reverted PP2Cm, BDK, BCKD activity, and BCAA and BCKA levels in HD-fed APN(-/-) and diabetic animals. Additionally, increased BCKD activity caused by APN administration was partially but significantly inhibited in PP2Cm knockout mice. Finally, APN-mediated upregulation of PP2Cm expression and BCKD activity were abolished when AMPK was inhibited. Collectively, we have provided the first direct evidence that APN is a novel regulator of PP2Cm and systematic BCAA levels, suggesting that targeting APN may be a pharmacological approach to ameliorating BCAA catabolism in the diabetic state. PMID:25071024

  2. Evolution of the biosynthesis of the branched-chain amino acids

    NASA Technical Reports Server (NTRS)

    Keefe, Anthony D.; Lazcano, Antonio; Miller, Stanley L.

    1995-01-01

    The origins of the biosynthetic pathways for the branched-chain amino acids cannot be understood in terms of the backwards development of the present acetolactate pathway because it contains unstable intermediates. We propose that the first biosynthesis of the branched-chain amino acids was by the reductive carboxylation of short branched chain fatty acids giving keto acids which were then transaminated. Similar reaction sequences mediated by nonspecific enzymes would produce serine and threomine from the abundant prebiotic compounds glycolic and lactic acids. The aromatic amino acids may also have first been synthesized in this way, e.g. tryptophan from indole acetic acid. The next step would have been the biosynthesis of leucine from alpha-ketoisovalerc acid. The acetolactate pathway developed subsequently. The first version of the Krebs cycle, which was used for amino acid biosynthesis, would have been assembled by making use fo the reductive carboxylation and leucine biosynthesis enzymes, and completed with the development of a single new enzyme, succinate dehydrogenase. This evolutionary scheme suggests that there may be limitations to inferring the origins of metabolism by a simple back extrapolation of current pathways.

  3. Branched-chain amino acid metabolism in rat muscle: abnormal regulation in acidosis

    SciTech Connect

    May, R.C.; Hara, Y.; Kelly, R.A.; Block, K.P.; Buse, M.G.; Mitch, W.E.

    1987-06-01

    Branched-chain amino acid (BCAA) metabolism is frequently abnormal in pathological conditions accompanied by chronic metabolic acidosis. To study how metabolic acidosis affects BCAA metabolism in muscle, rats were gavage fed a 14% protein diet with or without 4 mmol NH/sub 4/Cl x 100 g body wt/sup -1/ x day/sup -1/. Epitrochlearis muscles were incubated with L-(1-/sup 14/C)-valine and L-(1-/sup 14/C)leucine, and rates of decarboxylation, net transamination, and incorporation into muscle protein were measured. Plasma and muscle BCAA levels were lower in acidotic rats. Rates of valine and leucine decarboxylation and net transamination were higher in muscles from acidotic rats; these differences were associated with a 79% increase in the total activity of branched-chain ..cap alpha..-keto acid dehydrogenase and a 146% increase in the activated form of the enzyme. They conclude that acidosis affects the regulation of BCAA metabolism by enhancing flux through the transaminase and by directly stimulating oxidative catabolism through activation of branched-chain ..cap alpha..-keto acid dehydrogenase.

  4. A novel liquid chromatography tandem mass spectrometry method for simultaneous determination of branched-chain amino acids and branched-chain α-keto acids in human plasma.

    PubMed

    Li, Ruiting; Liu, Peifang; Liu, Peijia; Tian, Yuan; Hua, Yunfei; Gao, Yiqiao; He, Hua; Chen, Jiaqing; Zhang, Zunjian; Huang, Yin

    2016-06-01

    Branched-chain amino acids (BCAAs) and branched-chain α-keto acids (BCKAs) play significant biological roles as they are involved in protein and neurotransmitter synthesis as well as energy metabolism pathways. To routinely and accurately study the dynamics of BCAAs and BCKAs in human diseases, e.g. cerebral infarction, a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated. The plasma samples were deproteinized with acetonitrile, and then separated on a reversed phase C18 column with a mobile phase of 0.1 % formic acid (solvent A)-methanol (solvent B) using gradient elution. The detection of BCAAs and BCKAs was conducted in multiple reaction monitoring with positive/negative electrospray ionization switching mode. Biologically relevant isomers such as leucine and isoleucine were individually quantified by combining chromatographic separation and fragmentation. Good linearity (R (2) > 0.99) was obtained for all six analytes with the limits of detection from 0.1 to 0.2 µg/mL. The intra-day and inter-day accuracy ranged from 93.7 to 108.4 % and the relative standard deviation (RSD) did not exceed 15.0 %. The recovery was more than 80 % with RSD less than 14.0 %. The main improvements compared to related, state-of-the-art methods included enhanced sensitivity, enhanced separation of isomers, and reduced complexity of sample processing. Finally, the validated method was applied to analyze the plasma samples of healthy volunteers and patients suffering cerebral infarction, and significant differences in the concentration levels of BCAAs and BCKAs were observed. PMID:26984321

  5. Metabolism of branched-chain amino acids in leg muscles from tail-cast suspended intact and adrenalectomized rats

    NASA Technical Reports Server (NTRS)

    Jaspers, Stephen R.; Henriksen, Erik; Jacob, Stephan; Tischler, Marc E.

    1989-01-01

    The effects of muscle unloading, adrenalectomy, and cortisol treatment on the metabolism of branched-chain amino acids in the soleus and extensor digitorum longus of tail-cast suspended rats were investigated using C-14-labeled lucine, isoleucine, and valine in incubation studies. It was found that, compared to not suspended controls, the degradation of branched-chain amino acids in hind limb muscles was accelerated in tail-cast suspended rats. Adrenalectomy was found to abolish the aminotransferase flux and to diminish the dehydrogenase flux in the soleus. The data also suggest that cortisol treatment increases the rate of metabolism of branched-chain amino acids at the dehydrogenase step.

  6. High-energy radiation forming chain scission and branching in polypropylene

    NASA Astrophysics Data System (ADS)

    Otaguro, H.; de Lima, L. F. C. P.; Parra, D. F.; Lugão, A. B.; Chinelatto, M. A.; Canevarolo, S. V.

    2010-03-01

    The degradation of high molecular weight isotactic polypropylene (iPP) subjected to gamma rays irradiation up to 100 kGy in inert atmosphere was analyzed. The investigation relied upon complex viscosity, elastic modulus, gel fraction, morphology of the insoluble fraction and deconvoluted molecular weight distribution (MWD) curves. At low irradiation doses, already at 5 kGy, the MWD curve is strongly shifted to the low molecular weight side showing chain scission, which is confirmed using the calculated chain scission distribution function (CSDF). At high dose levels, the appearance of a shoulder in the high molecular weight side of the MWD curve indicates the formation of chain branching. The presence of a considerable insoluble fraction at these high dose levels indicates also the formation of cross-linking, which has different morphology then the insoluble fraction present in the original iPP. The rheological results show changes in the molecular structure of irradiated samples in agreement with the gel content data. The chromatographic and rheological data has shown that gamma irradiation of iPP produces chain scission, branching and cross-linking.

  7. Theoretical model to investigate the alkyl chain and anion dependent interactions of gemini surfactant with bovine serum albumin.

    PubMed

    Vishvakarma, Vijay K; Kumari, Kamlesh; Patel, Rajan; Dixit, V S; Singh, Prashant; Mehrotra, Gopal K; Chandra, Ramesh; Chakrawarty, Anand Kumar

    2015-05-15

    Surfactants are used to prevent the irreversible aggregation of partially refolded proteins and they also assist in protein refolding. We have reported the design and screening of gemini surfactant to stabilize bovine serum albumin (BSA) with the help of computational tool (iGEMDOCK). A series of gemini surfactant has been designed based on bis-N-alkyl nicotinate dianion via varying the alkyl group and anion. On changing the alkyl group and anion of the surfactant, the value of Log P changes means polarity of surfactant can be tuned. Further, the virtual screening of the gemini surfactant has been carried out based on generic evolutionary method. Herein, thermodynamic data was studied to determine the potential of gemini surfactant as BSA stabilizer. Computational tools help to find out the efficient gemini surfactant to stabilize the BSA rather than to use the surfactant randomly and directionless for the stabilization. It can be confirmed through the experimental techniques. Previously, researcher synthesized one of the designed and used gemini surfactant to stabilize the BSA and their interactions were confirmed through various techniques and computational docking. But herein, the authors find the most competent gemini surfactant to stabilize BSA using computational tools on the basis of energy score. Different from the single chain surfactant, the gemini surfactants exhibit much stronger electrostatic and hydrophobic interactions with the protein and are thus effective at much lower concentrations. Based on the present study, it is expected that gemini surfactants may prove useful in the protein stabilization operations and may thus be effectively employed to circumvent the problem of misfolding and aggregation.

  8. Mathematical modeling of the aquatic macrophyte inputs of mid-chain n-alkyl lipids to lake sediments: Implications for interpreting compound specific hydrogen isotopic records

    NASA Astrophysics Data System (ADS)

    Gao, Li; Hou, Juzhi; Toney, Jaime; MacDonald, Dana; Huang, Yongsong

    2011-07-01

    We present a systematic study of chain-length distributions and D/H ratios of n-alkyl lipids (both n-alkanes and n-alkanoic acids) in a wide range of terrestrial and aquatic plants around and in Blood Pond, Massachusetts, USA. The primary goal is to establish a model to quantitatively assess the aquatic plant inputs of the mid-chain length n-alkyl lipids to lake sediments and to determine the average hydrogen isotopic ratios of these lipids in different plants. Our results show that middle-chain n-alkyl lipids (C 21-C 23n-alkanes and C 20-C 24n-alkanoic acids) are exceptionally abundant in floating and submerged aquatic plants, in contrast to the dominance of long-chain n-alkyl lipids (C 27-C 31n-alkanes and C 26-C 32n-alkanoic acids) in other plant types, which are consistent with previously published data from Mountain Kenya and the Tibetan Plateau. Combining available data in different environmental settings allows us to establish statistically robust model distributions of n-alkyl lipids in floating/submerged macrophytes relative to other plant types. Based on the model distributions, we established a multi-source mixing model using a linear algebra approach, in order to quantify the aquatic inputs of mid-chain n-alkyl lipids in lake sediments. The results show that ˜97% of the mid-chain n-alkyl lipids (C 23n-alkane and C 22n-acid (behenic acid)) in Blood Pond sediments are derived from floating and submerged macrophytes. In addition, D/H ratios of C 22n-acid and C 23n-alkane in the floating and submerged plants from Blood Pond display relatively narrow ranges of variation (-161 ± 16‰ and -183 ± 18‰, respectively). Our study demonstrates that mid-chain n-alkyl lipids such as C 23n-alkane and C 22n-acid could be excellent recorders of past lake water isotopic ratios in lakes with abundant floating and submerged macrophyte inputs.

  9. Impact of chain length on antibacterial activity and hemocompatibility of quaternary N-alkyl and n,n-dialkyl chitosan derivatives.

    PubMed

    Sahariah, Priyanka; Benediktssdóttir, Berglind E; Hjálmarsdóttir, Martha Á; Sigurjonsson, Olafur E; Sørensen, Kasper K; Thygesen, Mikkel B; Jensen, Knud J; Másson, Már

    2015-05-11

    A highly efficient method for chemical modification of chitosan biopolymers by reductive amination to yield N,N-dialkyl chitosan derivatives was developed. The use of 3,6-O-di-tert-butyldimethylsilylchitosan as a precursor enabled the first 100% disubstitution of the amino groups with long alkyl chains. The corresponding mono N-alkyl derivatives were also synthesized, and all the alkyl compounds were then quaternized using an optimized procedure. These well-defined derivatives were studied for antibacterial activity against Gram positive S. aureus, E. faecalis, and Gram negative E. coli, P. aeruginosa, which could be correlated to the length of the alkyl chain, but the order was dependent on the bacterial strain. Toxicity against human red blood cells and human epithelial Caco-2 cells was found to be proportional to the length of the alkyl chain. The most active chitosan derivatives were found to be more selective for killing bacteria than the quaternary ammonium disinfectants cetylpyridinium chloride and benzalkonium chloride, as well as the antimicrobial peptides melittin and LL-37. PMID:25830631

  10. Self-assembly of long chain fatty acids: effect of a methyl branch.

    PubMed

    Liljeblad, Jonathan F D; Tyrode, Eric; Thormann, Esben; Dublanchet, Ann-Claude; Luengo, Gustavo; Magnus Johnson, C; Rutland, Mark W

    2014-09-01

    The morphology and molecular conformation of Langmuir-Blodgett deposited and floating monolayers of a selection of straight chain (eicosanoic acid, EA), iso (19-methyl eicosanoic acid, 19-MEA), and anteiso (18-methyl eicosanoic acid, 18-MEA) fatty acids have been investigated by Vibrational Sum Frequency Spectroscopy (VSFS), AFM imaging, and the Langmuir trough. While the straight chain fatty acid forms smooth, featureless monolayers, all the branched chain fatty acids display 10-50 nm sized domains (larger for 19-MEA than the 18-MEA) with a homogeneous size distribution. A model is suggested to explain the domain formation and size in terms of the branched fatty acid packing properties and the formation of hemispherical caps at the liquid-air interface. No difference between the chiral (S) form and the racemic mixture of the 18-MEA is observed with any of the utilized techniques. The aliphatic chains of the straight chain fatty acids appear to be oriented perpendicular to the sample surface, based on an orientational analysis of VSFS data and the odd/even effect. In addition, the selection of the subphase (neat water or CdCl2 containing water buffered to pH 6.0) used for the LB-deposition has a profound influence on the monolayer morphology, packing density, compressibility, and conformational order. Finally, the orientation of the 19-MEA dimethyl moiety is estimated, and a strategy for performing an orientational analysis to determine the complete molecular orientation of the aliphatic chains of 19-MEA and 18-MEA is outlined and discussed. PMID:25045762

  11. Molecular dynamics simulation of the interfacial structure of [C(n)mim][PF6] adsorbed on a graphite surface: effects of temperature and alkyl chain length.

    PubMed

    Dou, Q; Sha, M L; Fu, H Y; Wu, G Z

    2011-05-01

    The structures and diffusion behaviors of a series of ionic liquids [C(n)mim][PF(6)] (n = 1, 4, 8 and 12) on a graphite surface have been investigated by means of molecular dynamics simulation. It was found that three or four ordering layers of ionic liquids were formed near the graphite surface, and this layering structure was stable over the temperature range investigated. At the liquid/vacuum interface, the ionic liquid with a butyl chain had a monolayer ordering surface, while [C(8)mim][PF(6)] and [C(12)mim][PF(6)] exhibited a bilayer ordering with a polar domain sandwiched between two orientational nonpolar domains. More impressively, the simulated results showed that for the ionic liquids with alkyl chains longer than C(4), the adjacent alkyl chains in the whole film tended to be parallel to each other, with the imidazolium rings packed closely together. This indicated that the ionic liquids have a better regulated short-range structure than was previously expected. It was also found that both in the bottom layer and in the bulk region, the diffusion of the alkyl chains was much faster than that of the polar groups. However, as the alkyl chain length increased, the charge delocalization in the cation and the enhanced van der Waals interaction between the nonpolar groups contributed by reducing this difference in the diffusivity of major groups.

  12. Conversion of raw lignocellulosic biomass into branched long-chain alkanes through three tandem steps.

    PubMed

    Li, Chunrui; Ding, Daqian; Xia, Qineng; Liu, Xiaohui; Wang, Yanqin

    2016-07-01

    Synthesis of branched long-chain alkanes from renewable biomass has attracted intensive interest in recent years, but the feedstock for this synthesis is restricted to platform chemicals. Here, we develop an effective and energy-efficient process to convert raw lignocellulosic biomass (e.g., corncob) into branched diesel-range alkanes through three tandem steps for the first time. Furfural and isopropyl levulinate (LA ester) were prepared from hemicellulose and cellulose fractions of corncob in toluene/water biphasic system with added isopropanol, which was followed by double aldol condensation of furfural with LA ester into C15 oxygenates and the final hydrodeoxygenation of C15 oxygenates into branched long-chain alkanes. The core point of this tandem process is the addition of isopropanol in the first step, which enables the spontaneous transfer of levulinic acid (LA) into the toluene phase in the form of LA ester through esterification, resulting in LA ester co-existing with furfural in the same phase, which is the basis for double aldol condensation in the toluene phase. Moreover, the acidic aqueous phase and toluene can be reused and the residues, including lignin and humins in aqueous phase, can be separated and carbonized to porous carbon materials. PMID:27241180

  13. Impact of co-solvent chain branching on lithium-ion battery performance

    NASA Astrophysics Data System (ADS)

    Vetter, Jens; Buqa, Hilmi; Holzapfel, Michael; Novák, Petr

    The influence of the electrolyte in lithium-ion batteries on the reversible capacity and long-term cycling stability is not only determined by the salt and the film-forming solvent, but also, to a minor extent, by the co-solvent that is usually comprised in order to ensure suitable physical properties. Electrolytes containing three different isomers of butyl methyl carbonates were investigated in both, graphite half- and full-cells in order to determine the influence of co-solvent chain branching on the electrochemical performance. The reversible capacity obtained in SFG44 graphite (TIMCAL Ltd.) half-cells is higher for electrolytes with branched co-solvents and increases as the chain branching gets closer to the carbonate group. The long-term cycling stability, investigated in SLP30 graphite (TIMCAL Ltd.) half-cells, shows the same trend. The overall effect is rather small, but still perceivable in a full-cell set-up (SFG44/LiCoO 2). A possible pathway of interaction of the co-solvent via the structure and composition of the solid electrolyte interphase (SEI) is proposed.

  14. The formation of surface multilayers at the air-water interface from sodium diethylene glycol monoalkyl ether sulfate/AlCl3 solutions: the role of the alkyl chain length.

    PubMed

    Xu, Hui; Penfold, Jeffrey; Thomas, Robert K; Petkov, Jordan T; Tucker, Ian; Webster, John P R

    2013-10-15

    The influence of the alkyl chain length on surface multilayer formation at the air-water interface for the anionic surfactant sodium diethylene glycol monoalkyl ether sulfate, SAE2S, in the presence of Al(3+) multivalent counterions, in the form of AlCl3, is described. In the absence of electrolyte, the saturated monolayer adsorption is determined by the headgroup geometry and is independent of the alkyl chain length. In the presence of Al(3+) counterions, surface multilayer formation occurs, due to the strong SAE2S/Al(3+) binding and complexation. The neutron reflection data show that the alkyl chain length of the surfactant has a significant impact upon the evolution of the surface multilayer structure with surfactant and AlCl3 concentration. Increasing the alkyl chain length from decyl to tetradecyl results in the surface multilayer formation occurring at lower surfactant and AlCl3 concentrations. At the short alkyl chain lengths, decyl and dodecyl, the regions of multilayer formation with a small number of bilayers are increasingly extended with decreasing alkyl chain length. For the alkyl chain lengths of tetradecyl and hexadecyl, the surface behavior is further affected by decreases in the surfactant solubility in the presence of AlCl3, and this ultimately dominates the surface behavior at the longer alkyl chain lengths.

  15. Aquatic Macrophytes Inputs of Middle Chain Length n-alkyl Lipids into Lake Sediments: a Linear Algebra Approach

    NASA Astrophysics Data System (ADS)

    Gao, L.; Huang, Y.

    2009-12-01

    Quantitatively delineating multiple source inputs is a common but often difficult task in geological and environmental researches. Binary mixing model works well for simple two-component mixing problems when the two end members can be accurately defined. However, real world mixing problems usually involve more than two source components, and each component may have many composite profiles. Therefore, binary model is inadequate to provide an accurate estimate of contribution of all the end member sources. In such cases, linear combination model by solving linear algebra equations will have to be developed. In this study, we demonstrate the application of the linear algebra method to accurately calculate the percentage inputs of leaf waxes from different plant groups to lake sediments of Blood Pond and Rocky Pond in Massachusetts. We systematically sampled 28 species, including 6 tree species, 6 grass species, 7 emergent plants, 4 floating and 3 submerged aquatic plants around Blood Pond as well as 6 sediments samples of different depth. The distributions of these plants leaf waxes (n-alkanes and n-alkanoic acids) show distinctively different patterns, but also significant overlaps. To accurately quantify the percentage source inputs, we develop the 4-end member linear combination model. As we have an equation for each of the total 6 n-alkane compounds we use (C23 alkane ~C33 alkane), a 'least square fitting' is applied to solved the overdetermined linear system. Our results show that 91.7% of the total C23 alkane in sediments is derived from floating and submerged plants. We also applied our approach to Rocky Pond in southeastern Massachusetts and found >92 % of mid chain n-alkyl lipids are contributed by floating and submerged plants. Our results provide critical basis for using D/H ratios of mid-chain n-alkyl lipids (such as behenic acid) in lake sediments for reconstructing lake water D/H ratios.

  16. Structures and redox reactivities of copper complexes of (2-pyridyl)alkylamine ligands. Effects of the alkyl linker chain length.

    PubMed

    Osako, Takao; Ueno, Yoshiki; Tachi, Yoshimitsu; Itoh, Shinobu

    2003-12-01

    Ligand effects on the structures and redox reactivities of copper complexes have been examined using (2-pyridyl)alkylamine derivatives as the supporting ligands, where particular attention has been focused on the effects of the alkyl linker chain length connecting the tertiary amine nitrogen atom and the pyridine nucleus: N[bond]CH(2)[bond]Py (Pym) vs N[bond]CH(2)CH(2)[bond]Py (Pye). X-ray crystallographic analysis of the copper(I) complex of tridentate ligand (Phe)L(Pym2) [N,N-di(2-pyridylmethyl)-2-phenylethylamine] (complex 1) has demonstrated that it possesses a trigonal pyramidal geometry in which a d[bond]pi interaction with an eta(1)-binding mode exists between the metal ion and one of the ortho carbons of the phenyl ring of the ligand side arm (phenethyl). The result shows sharp contrast to the d[bond]pi interaction with an eta(2)-binding mode existing in the copper(I) complex of (Phe)L(Pye2) [N,N-di[2-(2-pyridyl)ethyl]-2-phenethylamine] (complex 2). Such a d-pi interaction has been shown to affect the stability of the copper(I) complex in CH(2)Cl(2). Oxygenation of copper(I) complex 1 supported by (Phe)L(Pym2) produces a bis(mu-oxo)dicopper(III) complex, also being in sharp contrast to the case of the copper(I) complex 2 with ligand (Phe)L(Pye2), which preferentially affords a (micro-eta(2):eta(2)-peroxo)dicopper(II) complex in the reaction with O(2). Such an effect of the alkyl linker chain length of the metal binding site has also been found to operate in the RSSR (disulfide)/2RS(-) (thiolate) redox system. Namely, ligand (S2,R)L(Pym1) (di[2-[(alkyl)(2-pyridinylmethyl)amino]ethyl] disulfide) with the methylene linker group (Pym) induced the reductive disulfide bond cleavage in the reaction with copper(I) ion to give a bis(micro-thiolato)dicopper(II) complex, while the ligand with the ethylene linker group (Pye), (S2,Bn)L(Pye1) (di[2-[(benzyl)(2-(2-pyridinyl)ethyl)amino]ethyl] disulfide), gave a disulfide-dicopper(I) complex. These ligand effects in the Cu

  17. Ultrafast charge-transfer reactions of indoline dyes with anchoring alkyl chains of varying length in mesoporous ZnO solar cells.

    PubMed

    Rohwer, Egmont; Minda, Iulia; Tauscher, Gabriele; Richter, Christoph; Miura, Hidetoshi; Schlettwein, Derck; Schwoerer, Heinrich

    2015-04-01

    Dye-sensitized solar cells based on a mesoporous ZnO substrate were sensitized with the indoline derivatives DN91, DN216 and DN285. The chromophore is the same for each of these dyes. They differ from each other in the length of an alkyl chain, which provides a second anchor to the ZnO surface and prolongs cell lifetime. Ultrafast transient absorption measurements reveal a correlation between the length of the alkyl chain and the fastest electron-injection process. The depopulation of the excited state and the associated emergence of the oxidized molecules are dominant spectral features in the transient absorption of the dyes with shorter alkyl chains. A slower picosecond-scale decay proceeds at constant rate for all three derivatives and is assigned to electron transfer into the trap states of ZnO. All assignments are in good agreement with a higher quantum efficiency of charge injection leading to higher short-circuit currents J(sc) for dyes with shorter alkyl chains. PMID:25652263

  18. 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. PMID:27001746

  19. Theoretical investigation on the kinetics and mechanisms of hydroxyl radical-induced transformation of parabens and its consequences for toxicity: Influence of alkyl-chain length.

    PubMed

    Gao, Yanpeng; Ji, Yuemeng; Li, Guiying; An, Taicheng

    2016-03-15

    As emerging organic contaminants (EOCs), the ubiquitous presence of preservative parabens in water causes a serious environmental concern. Hydroxyl radical ((•)OH) is a strong oxidant that can degrade EOCs through photochemistry in surface water environments as well as in advanced oxidation processes (AOPs). To better understand the degradation mechanisms, kinetics, and products toxicity of the preservative parabens in aquatic environments and AOPs, the (•)OH-initiated degradation reactions of the four parabens were investigated systematically using a computational approach. The four studied parabens with increase of alkyl-chain length were methylparaben (MPB), ethylparaben (EPB), propylparaben (PPB), and dibutylparaben (BPB). Results showed that the four parabens can be initially attacked by (•)OH through (•)OH-addition and H-abstraction routes. The (•)OH-addition route was more important for the degradation of shorter alkyl-chain parabens like MPB and EPB, while the H-abstraction route was predominant for the degradation of parabens with longer alkyl-chain for example PPB and BPB. In assessing the aquatic toxicity of parabens and their degradation products using the model calculations, the products of the (•)OH-addition route were found to be more toxic to green algae than original parabens. Although all degradation products were less toxic to daphnia and fish than corresponding parental parabens, they could be still harmful to these aquatic organisms. Furthermore, as alkyl-chain length increased, the ecotoxicity of parabens and their degradation products was found to be also increased. PMID:26773489

  20. PGC-1α-Mediated Branched-Chain Amino Acid Metabolism in the Skeletal Muscle

    PubMed Central

    Nagaike, Yuta; Morita, Akihito; Ogawa, Yoshihiro; Ezaki, Osamu; Takai-Igarashi, Takako; Kitaura, Yasuyuki; Shimomura, Yoshiharu; Kamei, Yasutomi; Miura, Shinji

    2014-01-01

    Peroxisome proliferator-activated receptor (PPAR) γ coactivator 1α (PGC-1α) is a coactivator of various nuclear receptors and other transcription factors, which is involved in the regulation of energy metabolism, thermogenesis, and other biological processes that control phenotypic characteristics of various organ systems including skeletal muscle. PGC-1α in skeletal muscle is considered to be involved in contractile protein function, mitochondrial function, metabolic regulation, intracellular signaling, and transcriptional responses. Branched-chain amino acid (BCAA) metabolism mainly occurs in skeletal muscle mitochondria, and enzymes related to BCAA metabolism are increased by exercise. Using murine skeletal muscle overexpressing PGC-1α and cultured cells, we investigated whether PGC-1α stimulates BCAA metabolism by increasing the expression of enzymes involved in BCAA metabolism. Transgenic mice overexpressing PGC-1α specifically in the skeletal muscle had increased the expression of branched-chain aminotransferase (BCAT) 2, branched-chain α-keto acid dehydrogenase (BCKDH), which catabolize BCAA. The expression of BCKDH kinase (BCKDK), which phosphorylates BCKDH and suppresses its enzymatic activity, was unchanged. The amount of BCAA in the skeletal muscle was significantly decreased in the transgenic mice compared with that in the wild-type mice. The amount of glutamic acid, a metabolite of BCAA catabolism, was increased in the transgenic mice, suggesting the activation of muscle BCAA metabolism by PGC-1α. In C2C12 cells, the overexpression of PGC-1α significantly increased the expression of BCAT2 and BCKDH but not BCKDK. Thus, PGC-1α in the skeletal muscle is considered to significantly contribute to BCAA metabolism. PMID:24638054

  1. Cholesterol Analogs with Degradation-resistant Alkyl Side Chains Are Effective Mycobacterium tuberculosis Growth Inhibitors.

    PubMed

    Frank, Daniel J; Zhao, Yan; Wong, Siew Hoon; Basudhar, Debashree; De Voss, James J; Ortiz de Montellano, Paul R

    2016-04-01

    Cholest-4-en-3-one, whether added exogenously or generated intracellularly from cholesterol, inhibits the growth ofMycobacterium tuberculosiswhen CYP125A1 and CYP142A1, the cytochrome P450 enzymes that initiate degradation of the sterol side chain, are disabled. Here we demonstrate that a 16-hydroxy derivative of cholesterol, which was previously reported to inhibit growth ofM. tuberculosis, acts by preventing the oxidation of the sterol side chain even in the presence of the relevant cytochrome P450 enzymes. The finding that (25R)-cholest-5-en-3β,16β,26-triol (1) (and its 3-keto metabolite) inhibit growth suggests that cholesterol analogs with non-degradable side chains represent a novel class of anti-mycobacterial agents. In accord with this, two cholesterol analogs with truncated, fluorinated side chains have been synthesized and shown to similarly block the growth in culture ofM. tuberculosis.

  2. O-alkylation of phenols for upgrading of coal-derived liquids; 1: Reaction of Phenols with Branched Olefins

    SciTech Connect

    Gould, K.A.; Long, R.B.

    1983-08-01

    Model phenolic compounds as well as coal-derived phenols were found to be readily etherified by reaction with 2-methyl-2-butene and an acid catalyst. The reaction is equilibrium limited with formation of ethers being favored at low temperatures and high olefin concentrations. Ring alkylation can be minimized by employing mild reaction conditions. Various acids were employed and 40% sulfuric acid in methanol was found to be superior to 40% sulfuric acid in water, especially at high olefin concentrations. The acid/methanol solutions were also found to be quite useful for extraction of phenols from coal naphtha. Increased steric bulk in the vicinity of the phenolic hydroxyl group was observed to retard etherification.

  3. Manipulating the morphology and textural property of γ-AlOOH by modulating the alkyl chain length of cation in ionic liquid

    SciTech Connect

    Tang, Zhe Hu, Xiaofu Liang, Jilei Zhao, Jinchong Liu, Yunqi Liu, Chenguang

    2013-06-01

    Graphical abstract: - Highlights: • γ-AlOOH was the only product in all experiments. • Different morphology of γ-AlOOH was obtained according to the alkyl chain length. • The textural property of γ-AlOOH was changed according to the alkyl chain length. • The possible formation mechanisms for hollow sphere and microflower were proposed. - Abstract: We demonstrated that the morphology and textural property of γ-AlOOH can be tuned by modulating the alkyl chain length of cation in [C{sub n}mim]{sup +}Cl{sup −} (n = 4, 8, 16). Using the short alkyl chain length-based [C{sub 4}mim]{sup +}Cl{sup −} as the structure-directed reagent, the morphology of γ-AlOOH was not changed and preserved as the hollow sphere structure in all experiments. The specific area and the number of small meso-pores of γ-AlOOH increased with the increase of [C{sub 4}mim]{sup +}Cl{sup −} dosage. While, using the larger alkyl chain length-based ionic liquids as the soft-template, such as [C{sub 8}mim]{sup +}Cl{sup −} and [C{sub 16}mim]{sup +}Cl{sup −}, the morphologies of γ-AlOOH were changed from initiative hollow spheres into the final microflowers. The specific areas of γ-AlOOH firstly increased then decreased with the increase of their dosage. The samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). Furthermore, the possible formation mechanisms of γ-AlOOH have been proposed.

  4. Effects of alkyl chain length and substituent pattern of fullerene bis-adducts on film structures and photovoltaic properties of bulk heterojunction solar cells.

    PubMed

    Tao, Ran; Umeyama, Tomokazu; Kurotobi, Kei; Imahori, Hiroshi

    2014-10-01

    A series of alkoxycarbonyl-substituted dihydronaphthyl-based [60]fullerene bis-adduct derivatives (denoted as C2BA, C4BA, and C6BA with the alkyl chain of ethyl, n-butyl, and n-hexyl, respectively) have been synthesized to investigate the effects of alkyl chain length and substituent pattern of fullerene bis-adducts on the film structures and photovoltaic properties of bulk heterojunction polymer solar cells. The shorter alkyl chain length caused lower solubility of the fullerene bis-adducts (C6BA > C4BA > C2BA), thereby resulting in the increased separation difficulty of respective bis-adduct isomers. The device performance based on poly(3-hexylthiophene) (P3HT) and the fullerene bis-adduct regioisomer mixtures was enhanced by shortening the alkyl chain length. When using the regioisomerically separated fullerene bis-adducts, the devices based on trans-2 and a mixture of trans-4 and e of C4BA exhibited the highest power conversion efficiencies of ca. 2.4%, which are considerably higher than those of the C6BA counterparts (ca. 1.4%) and the C4BA regioisomer mixture (1.10%). The film morphologies as well as electron mobilities of the P3HT:bis-adduct blend films were found to affect the photovoltaic properties considerably. These results reveal that the alkyl chain length and substituent pattern of fullerene bis-adducts significantly influence the photovoltaic properties as well as the film structures of bulk heterojunction solar cells.

  5. Regulation of taste-active components of meat by dietary branched-chain amino acids; effects of branched-chain amino acid antagonism.

    PubMed

    Imanari, M; Kadowaki, M; Fujimura, S

    2008-05-01

    1. The effects of dietary branched-chain amino acids (BCAAs) including leucine (Leu), isoleucine (Ile) and valine (Val) on taste-active components, especially free glutamate (Glu), in meat were investigated. 2. Broiler chickens (28 d old) were given varied dietary BCAA levels for 10 d before marketing. Dietary BCAA content ratios were either 100:100:100 (Low Leu group), 150:100:100 (Control group) or 150:150:150 (High Ile + Val group) for Leu:Ile:Val (% of each BCAA requirement according to NRC, 1994). Taste-related components of meat (free amino acids and ATP metabolites) and sensory scores of meat soup were estimated. 3. Free Glu content, the main taste-active component of meat, was significantly increased by dietary BCAA. Compared to the Control group, free Glu content increased by 30% in the High Ile + Val group. However, the inosine monophosphate (IMP) content in meat did not change among groups. 4. Sensory evaluation of meat soups showed that Control and High Ile + Val groups had different meat flavours. The sensory score of overall taste intensity was significantly higher in the High Ile + Val group. 5. These results suggest that dietary BCAA concentrations regulate free Glu in meat. Increasing dietary Ile + Val induces an increase in free Glu content of meat, improves meat taste and is more effective for increasing free Glu content in meat than decreasing dietary Leu level. PMID:18568754

  6. Dielectric relaxation of alkyl chains in graphite oxide and n-alkylammonium halides

    NASA Astrophysics Data System (ADS)

    Ai, Xiaoqian; Tian, Yuchen; Gu, Min; Yu, Ji; Tang, Tong B.

    2016-05-01

    The dynamic of n-alkylammonium halides and n-alkylammonium cations (n = 12, 14, 16, 18) intercalated in graphite oxide (GO) have been investigated with complex impedance spectroscopy. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, elemental analysis and thermogravimetry served to characterize the materials. The intercalated alkylammonium cations distributes as monolayers (when n = 12, 14 or 16) or bilayers (when n = 18), with their long axis parallel to GO layers, and with cations of headgroups bonded ionically to C-O- groups of GO; backbones of the confined molecules remain free. All halides and intercalation compounds suffer dielectric loss at low temperature. Arrhenius plots of the thermal dependence of the loss peaks, which are asymmetric, produce apparent activation energies that rise with increasing n. Ngai's correlated-state model helps to correct for effects of dipole-dipole interaction, leading to virtually identical values for actual activation energy of 110 meV ± 5%; the values are also almost the same as the barrier energy for internal rotation in the alkyl macromolecule. We conclude that the relaxation of the alkylammonium cations arises not from C3 reorientation of the CH3 at its headgroup, but from small-angle wobbling around its major axis, an intrinsic motion.

  7. Side chain variations radically alter the diffusion of poly(2-alkyl-2-oxazoline) functionalised nanoparticles through a mucosal barrier.

    PubMed

    Mansfield, Edward D H; de la Rosa, Victor R; Kowalczyk, Radoslaw M; Grillo, Isabelle; Hoogenboom, Richard; Sillence, Katy; Hole, Patrick; Williams, Adrian C; Khutoryanskiy, Vitaliy V

    2016-08-16

    Functionalised nanomaterials are gaining popularity for use as drug delivery vehicles and, in particular, mucus penetrating nanoparticles may improve drug bioavailability via the oral route. To date, few polymers have been investigated for their muco-penetration, and the effects of systematic structural changes to polymer architectures on the penetration and diffusion of functionalised nanomaterials through mucosal tissue have not been reported. We investigated the influence of poly(2-oxazoline) alkyl side chain length on nanoparticle diffusion; poly(2-methyl-2-oxazoline), poly(2-ethyl-2-oxazoline), and poly(2-n-propyl-2-oxazoline) were grafted onto the surface of thiolated silica nanoparticles and characterised by FT-IR, Raman and NMR spectroscopy, thermogravimetric analysis, and small angle neutron scattering. Diffusion coefficients were determined in water and in a mucin dispersion (using Nanoparticle Tracking Analysis), and penetration through a mucosal barrier was assessed using an ex vivo fluorescence technique. The addition of a single methylene group in the side chain significantly altered the penetration and diffusion of the materials in both mucin dispersions and mucosal tissue. Nanoparticles functionalised with poly(2-methyl-2-oxazoline) were significantly more diffusive than particles with poly(2-ethyl-2-oxazoline) while particles with poly(2-n-propyl-2-oxazoline) showed no significant increase compared to the unfunctionalised particles. These data show that variations in the polymer structure can radically alter their diffusive properties with clear implications for the future design of mucus penetrating systems. PMID:27400181

  8. Biologically compatible, phosphorescent dimetallic rhenium complexes linked through functionalized alkyl chains: syntheses, spectroscopic properties, and applications in imaging microscopy.

    PubMed

    Balasingham, Rebeca G; Thorp-Greenwood, Flora L; Williams, Catrin F; Coogan, Michael P; Pope, Simon J A

    2012-02-01

    A range of luminescent, dimetallic complexes based upon the rhenium fac-tricarbonyl diimine core, linked by aliphatic chains of varying lengths and functionality, have been synthesized and their photophysical properties examined. Each complex displays characteristic (3)M(Re)L(diimine)CT emission in aerated acetonitrile solution, with long lifetimes in the range of 129-248 ns and corresponding quantum yields in the range 3.2-8.0%. In aqueous solution, as opposed to acetonitrile, the complexes generally show a small hypsochromic shift in λ(em) and an extension of the (3)MLCT lifetime, attributed to a hydrophobically driven association of the alkyl chains with the rhenium-bound diimine units. In live cell imaging experiments using MCF7 cells the complexes all show good uptake by non-energy dependent mechanisms without endosomal entrainment, and with varying propensity to localize in organelles. The degrees of uptake and localization properties are discussed in terms of the length and chemical nature of the linkers, and in terms of the likely interactions between these and the various cellular components encountered.

  9. Dual Catalysis Using Boronic Acid and Chiral Amine: Acyclic Quaternary Carbons via Enantioselective Alkylation of Branched Aldehydes with Allylic Alcohols.

    PubMed

    Mo, Xiaobin; Hall, Dennis G

    2016-08-31

    A ferrocenium boronic acid salt activates allylic alcohols to generate transient carbocations that react with in situ-generated chiral enamines from branched aldehydes. The optimized conditions afford the desired acyclic products embedding a methyl-aryl quaternary carbon center with up to 90% yield and 97:3 enantiomeric ratio, with only water as the byproduct. This noble-metal-free method complements alternative methods that are incompatible with carbon-halogen bonds and other sensitive functional groups. PMID:27518200

  10. Adipose tissue monomethyl branched chain fatty acids and insulin sensitivity: effects of obesity and weight loss

    PubMed Central

    Su, Xiong; Magkos, Faidon; Zhou, Dequan; Eagon, J. Christopher; Fabbrini, Elisa; Okunade, Adewole L.; Klein, Samuel

    2014-01-01

    Objective An increase in circulating branched-chain amino acids (BCAA) is associated with insulin resistance. Adipose tissue is a potentially important site for BCAA metabolism. We evaluated whether monomethyl branched chain fatty acids (mmBCFA) in adipose tissue, which are likely derived from BCAA catabolism, are associated with insulin sensitivity. Design and Methods Insulin-stimulated glucose disposal was determined by using the hyperinsulinemic-euglycemic clamp procedure with stable isotope glucose tracer infusion, in 9 lean and 9 obese subjects, and in a separate group of 9 obese subjects before and 1 year after Roux-en-Y gastric bypass (RYGB) surgery (38% weight loss). Adipose tissue mmBCFA content was measured in tissue biopsies taken in the basal state. Results Total adipose tissue mmBCFA content was ~30% lower in obese than lean subjects (P = 0.02), and increased by ~65% after weight loss in the RYGB group (P = 0.01). Adipose tissue mmBCFA content correlated positively with skeletal muscle insulin sensitivity (R2 = 35%, P = 0.01, n = 18). Conclusions These results demonstrate a novel association between adipose tissue mmBCFA content and obesity-related insulin resistance. Additional studies are needed to determine whether the association between adipose tissue mmBCFA and muscle insulin sensitivity is causal or a simple association. PMID:25328153

  11. Branched-chain amino acid supplementation: impact on signaling and relevance to critical illness.

    PubMed

    Mattick, John S A; Kamisoglu, Kubra; Ierapetritou, Marianthi G; Androulakis, Ioannis P; Berthiaume, Francois

    2013-01-01

    The changes that occur in mammalian systems following trauma and sepsis, termed systemic inflammatory response syndrome, elicit major changes in carbohydrate, protein, and energy metabolism. When these events persist for too long they result in a severe depletion of lean body mass, multiple organ dysfunction, and eventually death. Nutritional supplementation has been investigated to offset the severe loss of protein, and recent evidence suggests that diets enriched in branched-chain amino acids (BCAAs) may be especially beneficial. BCAAs are metabolized in two major steps that are differentially expressed in muscle and liver. In muscle, BCAAs are reversibly transaminated to the corresponding α-keto acids. For the complete degradation of BCAAs, the α-keto acids must travel to the liver to undergo oxidation. The liver, in contrast to muscle, does not significantly express the branched-chain aminotransferase. Thus, BCAA degradation is under the joint control of both liver and muscle. Recent evidence suggests that in liver, BCAAs may perform signaling functions, more specifically via activation of mTOR (mammalian target of rapamycin) signaling pathway, influencing a wide variety of metabolic and synthetic functions, including protein translation, insulin signaling, and oxidative stress following severe injury and infection. However, understanding of the system-wide effects of BCAAs that integrate both metabolic and signaling aspects is currently lacking. Further investigation in this respect will help rationalize the design and optimization of nutritional supplements containing BCAAs for critically ill patients. PMID:23554299

  12. Branched-chain amino acid catabolism is a conserved regulator of physiological ageing

    PubMed Central

    Mansfeld, Johannes; Urban, Nadine; Priebe, Steffen; Groth, Marco; Frahm, Christiane; Hartmann, Nils; Gebauer, Juliane; Ravichandran, Meenakshi; Dommaschk, Anne; Schmeisser, Sebastian; Kuhlow, Doreen; Monajembashi, Shamci; Bremer-Streck, Sibylle; Hemmerich, Peter; Kiehntopf, Michael; Zamboni, Nicola; Englert, Christoph; Guthke, Reinhard; Kaleta, Christoph; Platzer, Matthias; Sühnel, Jürgen; Witte, Otto W.; Zarse, Kim; Ristow, Michael

    2015-01-01

    Ageing has been defined as a global decline in physiological function depending on both environmental and genetic factors. Here we identify gene transcripts that are similarly regulated during physiological ageing in nematodes, zebrafish and mice. We observe the strongest extension of lifespan when impairing expression of the branched-chain amino acid transferase-1 (bcat-1) gene in C. elegans, which leads to excessive levels of branched-chain amino acids (BCAAs). We further show that BCAAs reduce a LET-363/mTOR-dependent neuro-endocrine signal, which we identify as DAF-7/TGFβ, and that impacts lifespan depending on its related receptors, DAF-1 and DAF-4, as well as ultimately on DAF-16/FoxO and HSF-1 in a cell-non-autonomous manner. The transcription factor HLH-15 controls and epistatically synergizes with BCAT-1 to modulate physiological ageing. Lastly and consistent with previous findings in rodents, nutritional supplementation of BCAAs extends nematodal lifespan. Taken together, BCAAs act as periphery-derived metabokines that induce a central neuro-endocrine response, culminating in extended healthspan. PMID:26620638

  13. Genome-Wide Analysis of Branched-Chain Amino Acid Levels in Arabidopsis Seeds[W

    PubMed Central

    Angelovici, Ruthie; Lipka, Alexander E.; Deason, Nicholas; Gonzalez-Jorge, Sabrina; Lin, Haining; Cepela, Jason; Buell, Robin; Gore, Michael A.; DellaPenna, Dean

    2013-01-01

    Branched-chain amino acids (BCAAs) are three of the nine essential amino acids in human and animal diets and are important for numerous processes in development and growth. However, seed BCAA levels in major crops are insufficient to meet dietary requirements, making genetic improvement for increased and balanced seed BCAAs an important nutritional target. Addressing this issue requires a better understanding of the genetics underlying seed BCAA content and composition. Here, a genome-wide association study and haplotype analysis for seed BCAA traits in Arabidopsis thaliana revealed a strong association with a chromosomal interval containing two BRANCHED-CHAIN AMINO ACID TRANSFERASES, BCAT1 and BCAT2. Linkage analysis, reverse genetic approaches, and molecular complementation analysis demonstrated that allelic variation at BCAT2 is responsible for the natural variation of seed BCAAs in this interval. Complementation analysis of a bcat2 null mutant with two significantly different alleles from accessions Bayreuth-0 and Shahdara is consistent with BCAT2 contributing to natural variation in BCAA levels, glutamate recycling, and free amino acid homeostasis in seeds in an allele-dependent manner. The seed-specific phenotype of bcat2 null alleles, its strong transcription induction during late seed development, and its subcellular localization to the mitochondria are consistent with a unique, catabolic role for BCAT2 in BCAA metabolism in seeds. PMID:24368787

  14. The complex role of branched chain amino acids in diabetes and cancer.

    PubMed

    O'Connell, Thomas M

    2013-01-01

    The obesity and diabetes epidemics are continuing to spread across the globe. There is increasing evidence that diabetes leads to a significantly higher risk for certain types of cancer. Both diabetes and cancer are characterized by severe metabolic perturbations and the branched chain amino acids (BCAAs) appear to play a significant role in both of these diseases. These essential amino acids participate in a wide variety of metabolic pathways, but it is now recognized that they are also critical regulators of a number of cell signaling pathways. An elevation in branched chain amino acids has recently been shown to be significantly correlated with insulin resistance and the future development of diabetes. In cancer, the normal demands for BCAAs are complicated by the conflicting needs of the tumor and the host. The severe muscle wasting syndrome experience by many cancer patients, known as cachexia, has motivated the use of BCAA supplementation. The desired improvement in muscle mass must be balanced by the need to avoid providing materials for tumor proliferation. A better understanding of the complex functions of BCAAs could lead to their use as biomarkers of the progression of certain cancers in diabetic patients. PMID:24958258

  15. The Complex Role of Branched Chain Amino Acids in Diabetes and Cancer

    PubMed Central

    O’Connell, Thomas M.

    2013-01-01

    The obesity and diabetes epidemics are continuing to spread across the globe. There is increasing evidence that diabetes leads to a significantly higher risk for certain types of cancer. Both diabetes and cancer are characterized by severe metabolic perturbations and the branched chain amino acids (BCAAs) appear to play a significant role in both of these diseases. These essential amino acids participate in a wide variety of metabolic pathways, but it is now recognized that they are also critical regulators of a number of cell signaling pathways. An elevation in branched chain amino acids has recently been shown to be significantly correlated with insulin resistance and the future development of diabetes. In cancer, the normal demands for BCAAs are complicated by the conflicting needs of the tumor and the host. The severe muscle wasting syndrome experience by many cancer patients, known as cachexia, has motivated the use of BCAA supplementation. The desired improvement in muscle mass must be balanced by the need to avoid providing materials for tumor proliferation. A better understanding of the complex functions of BCAAs could lead to their use as biomarkers of the progression of certain cancers in diabetic patients. PMID:24958258

  16. Effect of cation type, alkyl chain length, adsorbate size on adsorption kinetics and isotherms of bromide ionic liquids from aqueous solutions onto microporous fabric and granulated activated carbons.

    PubMed

    Hassan, Safia; Duclaux, Laurent; Lévêque, Jean-Marc; Reinert, Laurence; Farooq, Amjad; Yasin, Tariq

    2014-11-01

    The adsorption from aqueous solution of imidazolium, pyrrolidinium and pyridinium based bromide ionic liquids (ILs) having different alkyl chain lengths was investigated on two types of microporous activated carbons: a fabric and a granulated one, well characterized in terms of surface chemistry by "Boehm" titrations and pH of point of zero charge measurements and of porosity by N2 adsorption at 77 K and CO2 adsorption at 273 K. The influence of cation type, alkyl chain length and adsorbate size on the adsorption properties was analyzed by studying kinetics and isotherms of eight different ILs using conductivity measurements. Equilibrium studies were carried out at different temperatures in the range [25-55 °C]. The incorporation of ILs on the AC porosity was studied by N2 adsorption-desorption measurements at 77 K. The experimental adsorption isotherms data showed a good correlation with the Langmuir model. Thermodynamic studies indicated that the adsorption of ILs onto activated carbons was an exothermic process, and that the removal efficiency increased with increase in alkyl chain length, due to the increase in hydrophobicity of long chain ILs cations determined with the evolution of the calculated octanol-water constant (Kow). The negative values of free energies indicated that adsorption of ILs with long chain lengths having hydrophobic cations was more spontaneous at the investigated temperatures.

  17. Impact of Alkyl Chain Length on the Transition of Hexagonal Liquid Crystal-Wormlike Micelle-Gel in Ionic Liquid-Type Surfactant Aqueous Solutions without Any Additive.

    PubMed

    Hu, Yimin; Han, Jie; Ge, Lingling; Guo, Rong

    2015-11-24

    The search for functional supramolecular aggregations with different structure has attracted interest of chemists because they have the potential in industrial and technological application. Hydrophobic interaction has great influence on the formation of these aggregations, such as hexagonal liquid crystals, wormlike micelles, hydrogels, etc. So a systematical investigation was done to investigate the influence of alkyl chain length of surfactants on the aggregation behavior in water. The aggregation behavior of 1-hexadecyl-3-alkyl imidazolium bromide and water has been systematically investigated. These ionic liquid surfactants are denoted as C16-Cn (n = 2, 3, 4, 6, 8, 9, 10, 12, 14, 16). The rheological behavior and microstructure were characterized via a combination of rheology, cryo-etch scanning electron microscopy, polarization optical microscopy, and X-ray crystallography. The alkyl chain has great influence on the formation of surfactant aggregates in water at the molecular level. With increasing alkyl chain length, different aggregates, such as hexagonal liquid crystals, wormlike micelles, and hydrogels can be fabricated: C16-C2 aqueous solution only forms hexagonal liquid crystal; C16-C3 aqueous solution forms wormlike micelle and hexagonal liquid crystal; C16-C4, C16-C6 and C16-C8 aqueous solutions only form wormlike micelle; C16-C9 aqueous solution experiences a transition between wormlike micelle and hydrogel; C16-C10, C16-C12, C16-C14 and C16-C16 only form hydrogel. The mechanism of the transition of different aggregation with increasing alkyl chain length was also proposed.

  18. A pilot, short-term dietary manipulation of branched chain amino acids has modest influence on fasting levels of branched chain amino acids

    PubMed Central

    Cavallaro, Nicole Landa; Garry, Jamie; Shi, Xu; Gerszten, Robert E.; Anderson, Ellen J.; Walford, Geoffrey A.

    2016-01-01

    Background Elevated fasting levels of branched chain amino acids (BCAAs: valine, isoleucine, leucine) in venous blood are associated with a variety of metabolic impairments, including increased risk of type 2 diabetes (T2D). Fasting BCAA levels are influenced by non-dietary factors. However, it is unknown whether fasting BCAAs can be altered through manipulation of dietary intake alone. Objective To test whether a specific dietary intervention, using differences in BCAA intake, alters fasting BCAA levels independent of other factors. Design Five healthy male volunteers underwent 4 days of a low and 4 days of a high BCAA content dietary intervention (ClinicalTrials.gov [NCT02110602]). All food and supplements were provided. Fasting BCAAs were measured from venous blood samples by mass spectrometry at baseline and after each intervention. Results Diets were isocaloric; contained equal percentages of calories from carbohydrate, fats, and protein; and differed from each other in BCAA content (1.5±0.1 vs. 14.0±0.6 g for valine; 4.5±0.9 g vs. 13.8±0.5 g for isoleucine; 2.1±0.2 g vs. 27.1±1.0 g for leucine; p<0.0001 for all). Fasting valine was significantly lower (p=0.02) and fasting isoleucine and leucine were numerically lower following the low BCAA content vs. the high BCAA content diet levels. The inter-individual response to the dietary interventions was variable and not explained by adherence. Conclusion Short-term dietary manipulation of BCAA intake led to modest changes in fasting levels of BCAAs. The approach from our pilot study can be expanded to test the metabolic implications of dietary BCAA manipulation. PMID:26781817

  19. Metabolic switch during adipogenesis: From branched chain amino acid catabolism to lipid synthesis.

    PubMed

    Halama, Anna; Horsch, Marion; Kastenmüller, Gabriele; Möller, Gabriele; Kumar, Pankaj; Prehn, Cornelia; Laumen, Helmut; Hauner, Hans; Hrabĕ de Angelis, Martin; Beckers, Johannes; Suhre, Karsten; Adamski, Jerzy

    2016-01-01

    Fat cell metabolism has an impact on body homeostasis and its proper function. Nevertheless, the knowledge about simultaneous metabolic processes, which occur during adipogenesis and in mature adipocytes, is limited. Identification of key metabolic events associated with fat cell metabolism could be beneficial in the field of novel drug development, drug repurposing, as well as for the discovery of patterns predicting obesity risk. The main objective of our work was to provide comprehensive characterization of metabolic processes occurring during adipogenesis and in mature adipocytes. In order to globally determine crucial metabolic pathways involved in fat cell metabolism, metabolomics and transcriptomics approaches were applied. We observed significantly regulated metabolites correlating with significantly regulated genes at different stages of adipogenesis. We identified the synthesis of phosphatidylcholines, the metabolism of even and odd chain fatty acids, as well as the catabolism of branched chain amino acids (BCAA; leucine, isoleucine and valine) as key regulated pathways. Our further analysis led to identification of an enzymatic switch comprising the enzymes Hmgcs2 (3-hydroxy-3-methylglutaryl-CoA synthase) and Auh (AU RNA binding protein/enoyl-CoA hydratase) which connects leucine degradation with cholesterol synthesis. In addition, propionyl-CoA, a product of isoleucine degradation, was identified as a putative substrate for odd chain fatty acid synthesis. The uncovered crosstalks between BCAA and lipid metabolism during adipogenesis might contribute to the understanding of molecular mechanisms of obesity and have potential implications in obesity prediction. PMID:26408941

  20. Infusion of branched-chain enriched amino acid solution in patients with hepatic encephalopathy.

    PubMed

    Freund, H; Dienstag, J; Lehrich, J; Yoshimura, N; Bradford, R R; Rosen, H; Atamian, S; Slemmer, E; Holroyde, J; Fischer, J E

    1982-08-01

    Hospitalized patients with hepatic insufficiency often suffer from severe catabolic states and are in urgent need of nutritional support during their acute illness. Protein intolerence, however, remains a significant problem with respect to the provision of adequate nutrition, either enterally or parenterally. The following report is an anecdotal series of 63 consecutive patients in a large urban hospital treated prospectively with nutritional support using a prototype high branched-chain amino acid solution (FO80) given by technique of total parenteral nutrition by the subclavian or internal jugular route with hypertonic dextrose. Sixty-three patients, of which 42 had chronic liver disease (cirrhosis) with acute decompensation and 17 with acute hepatic injury as well as four with hepatorenal syndrome, are the subject of this report. All required intravenous nutritional support and were either intolerant to commercially available parenteral nutrition solutions or were in hepatic encephalopathy at the time they were initially seen. The cirrhotic patients had been hospitalized for a mean of 14.5 +/- 1.9 days before therapy, had a mean bilirubin of 13 mg/100 ml, and had been in coma for 4.8 +/- 0.7 days despite standard therapy. Patients with acute hepatitis had been in the hospital for 16.2 +/- 4.1 days before therapy, had a mean bilirubin of 25 mg/100 ml, and had been in coma 5.2 +/- 1.6 days before therapy. Routine tests of liver function, blood chemistries, amino acids, EEGs, and complex neurological testing including Reitan trailmaking tests were used in the evaluation of these patients. Up to 120 grams of synthetic amino acid solution with hypertonic dextrose was tolerated in these patients with improvement noted in encephalopathy of at least one grade in 87% of the patients with cirrhosis and 75% of the patients with hepatitis. Nitrogen balance was achieved when 75 to 80 grams of synthetic amino acids were administered. Survival was 45% in the cirrhotic group

  1. Light-Induced ESR Studies of Quadrimolecular Recombination Kinetics of Photogenerated Charge Carriers in Regioregular Poly(3-alkylthiophene)/C60 Composites: Alkyl Chain Dependence

    NASA Astrophysics Data System (ADS)

    Tanaka, Hisaaki; Hasegawa, Naoki; Sakamoto, Tomotaka; Marumoto, Kazuhiro; Kuroda, Shin-ichi

    2007-08-01

    Light-induced ESR (LESR) measurements have been performed on the composites of regioregular poly(3-alkylthiophene) (RR-P3AT) and C60 by using polymers having different alkyl chains (CmH2m+1 with m=6, 8, 10, 12). The quadrimolecular recombination (QR) kinetics of photogenerated charge carriers, previously reported, have been confirmed for all the composites from the excitation power (Iex) dependence of the LESR intensity showing an ˜Iex0.25 dependence. The time decay of LESR intensity is also consistent with the QR model. Considering that only bimolecular recombination is observed in regiorandom polymer composites, the occurrence of QR strongly suggests the formation of doubly charged states, either bipolarons or polaron pairs on the regioregular polymer chains. On the other hand, the QR rate constant γ has been found to exhibit weak alkyl chain dependence, contrary to the case of the field-effect mobility of pure regioregular polymers with systematic alkyl chain dependence. This implies the significant contribution of the polymer and fullerene interface in determining γ.

  2. Influence of alkyl chain length and anion species on ionic liquid structure at the graphite interface as a function of applied potential.

    PubMed

    Li, Hua; Wood, Ross J; Endres, Frank; Atkin, Rob

    2014-07-16

    Atomic force microscopy (AFM) force measurements elucidate the effect of cation alkyl chain length and the anion species on ionic liquid (IL) interfacial structure at highly ordered pyrolytic graphite (HOPG) surfaces as a function of potential. Three ILs are examined: 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM] FAP), 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([EMIM] FAP), and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM] TFSA). The step-wise force-distance profiles indicate the ILs adopt a multilayered morphology near the surface. When the surface is biased positively or negatively versus Pt quasireference electrode, both the number of steps, and the force required to rupture each step increase, indicating stronger interfacial structure. At all potentials, push-through forces for [HMIM] FAP are the highest, because the long alkyl chain results in strong cohesive interactions between cations, leading to well-formed layers that resist the AFM tip. The most layers are observed for [EMIM] FAP, because the C2 chains are relatively rigid and the dimensions of the cation and anion are similar, facilitating neat packing. [EMIM] TFSA has the smallest push-through forces and fewest layers, and thus the weakest interfacial structure. Surface-tip attractive forces are measured for all ILs. At the same potential, the attractions are the strongest for [EMIM] TFSA and the weakest for [HMIM] FAP because the interfacial layers are better formed for the longer alkyl chain cation. This means interfacial forces are stronger, which masks the weak attractive forces.

  3. DNA-directed alkylating agents. 3. Structure-activity relationships for acridine-linked aniline mustards: consequences of varying the length of the linker chain.

    PubMed

    Valu, K K; Gourdie, T A; Boritzki, T J; Gravatt, G L; Baguley, B C; Wilson, W R; Wakelin, L P; Woodgate, P D; Denny, W A

    1990-11-01

    Four series of acridine-linked aniline mustards have been prepared and evaluated for in vitro cytotoxicity, in vivo antitumor activity, and DNA cross-linking ability. The anilines were attached to the DNA-intercalating acridine chromophores by link groups (-O-, -CH2-, -S-, and -SO2-) of widely varying electronic properties, providing four series of widely differing mustard reactivity where the alkyl chain linking the acridine and mustard moieties was varied from two to five carbons. Relationships were sought between chain length and biological properties. Within each series, increasing the chain length did not alter the reactivity of the alkylating moiety but did appear to position it differently on the DNA, since cross-linking ability (measured by agarose gel assay) altered with chain length, being maximal with the C4 analogue. The in vivo antitumor activities of the compounds depended to some extent on the reactivity of the mustard, with the least reactive SO2 compounds being inactive. However, DNA-targeting did appear to allow the use of less reactive mustards, since the S-linked acridine mustards showed significant activity whereas the parent S-mustard did not. Within each active series, the most active compound was the C4 homologue, suggesting some relationship between activity and extent of DNA alkylation.

  4. Chain-length dependence of the dissociation dynamics of oriented molecular adsorbates: n-alkyl bromides on GaAs(110)

    SciTech Connect

    Khan, K.A.; Camillone, N. III; Osgood, R.M. Jr.

    1999-07-01

    Brominated hydrocarbons adsorbed on semiconductor surfaces serve as ideal model systems for investigating the photoinduced chemistry of oriented molecules in the condensed phase. Under UV irradiation these adsorbates dissociate via attachment of photoexcited substrate electrons giving rise to energetic alkyl and surface-bound bromine fragments. In this report the authors describe the effect on the fragmentation dynamics due to systematic variation of the complexity (alkyl chain length) of the adsorbate. Increasing the length of the alkyl chain leads to distinct changes in the alkyl fragment angular distributions. For methyl bromide, the angular distribution is dominated by a focused beam of directly ejected hyperthermal methyl radicals at 44{degree} (in the [0{bar 1}] direction) from the surface normal. While a similar direct beam is observed for ethyl and propyl bromide, inelastic scattering of these fragments is found to result in increased importance of a slower diffuse cos{sup n} {theta} desorption. In addition, significant retention of alkyl fragments is detected by postirradiation thermal desorption measurements for these longer-chain homologues. Increasing the number of degrees of freedom of the adsorbate is also observed to dramatically alter the energetics of the ejection of the photofragments from the surface. As the number of carbons in the fragment is increased from one to three, the average energy of the directly ejected radicals decreases from 1.48 to 1.1 to 0.69 eV (UV incident at {lambda} = 193 nm). Variations in the energy and angular distributions are discussed in terms of initial adsorbate orientation, energy partitioning into rovibrational modes, and influence of radical-surface interactions.

  5. Tissue of origin dictates branched-chain amino acid metabolism in mutant Kras-driven cancers.

    PubMed

    Mayers, Jared R; Torrence, Margaret E; Danai, Laura V; Papagiannakopoulos, Thales; Davidson, Shawn M; Bauer, Matthew R; Lau, Allison N; Ji, Brian W; Dixit, Purushottam D; Hosios, Aaron M; Muir, Alexander; Chin, Christopher R; Freinkman, Elizaveta; Jacks, Tyler; Wolpin, Brian M; Vitkup, Dennis; Vander Heiden, Matthew G

    2016-09-01

    Tumor genetics guides patient selection for many new therapies, and cell culture studies have demonstrated that specific mutations can promote metabolic phenotypes. However, whether tissue context defines cancer dependence on specific metabolic pathways is unknown. Kras activation and Trp53 deletion in the pancreas or the lung result in pancreatic ductal adenocarinoma (PDAC) or non-small cell lung carcinoma (NSCLC), respectively, but despite the same initiating events, these tumors use branched-chain amino acids (BCAAs) differently. NSCLC tumors incorporate free BCAAs into tissue protein and use BCAAs as a nitrogen source, whereas PDAC tumors have decreased BCAA uptake. These differences are reflected in expression levels of BCAA catabolic enzymes in both mice and humans. Loss of Bcat1 and Bcat2, the enzymes responsible for BCAA use, impairs NSCLC tumor formation, but these enzymes are not required for PDAC tumor formation, arguing that tissue of origin is an important determinant of how cancers satisfy their metabolic requirements. PMID:27609895

  6. A Chiral, Photoluminescent, and Spin-Canted {Cu(I)Re(IV)2}n Branched Chain.

    PubMed

    Martínez-Lillo, José; Armentano, Donatella; Fortea-Pérez, Francisco R; Stiriba, Salah-Eddine; De Munno, Giovanni; Lloret, Francesc; Julve, Miguel; Faus, Juan

    2015-05-18

    A new heteroleptic 1D Cu(I)-Re(IV) coordination polymer of the formula {Cu(I)Re(IV)Cl4(μ-Cl)(μ-pyz)[Re(IV)Cl4(μ-bpym)]}n·nMeNO2 (1; pyz = pyrazine, bpym = 2,2'-bipyrimidine) has been prepared through the Cu(I)-mediated self-assembly of two different Re(IV) metalloligands, namely, [ReCl5(pyz)](-) and [ReCl4(bpym)]. 1 consists of chiral branched chains with an overall rack-type architecture displaying photoemission and magnetic ordering. These results constitute a first step toward making new multifunctional magnetic materials based on mixed 3d-5d molecular systems.

  7. Tissue of origin dictates branched-chain amino acid metabolism in mutant Kras-driven cancers.

    PubMed

    Mayers, Jared R; Torrence, Margaret E; Danai, Laura V; Papagiannakopoulos, Thales; Davidson, Shawn M; Bauer, Matthew R; Lau, Allison N; Ji, Brian W; Dixit, Purushottam D; Hosios, Aaron M; Muir, Alexander; Chin, Christopher R; Freinkman, Elizaveta; Jacks, Tyler; Wolpin, Brian M; Vitkup, Dennis; Vander Heiden, Matthew G

    2016-09-01

    Tumor genetics guides patient selection for many new therapies, and cell culture studies have demonstrated that specific mutations can promote metabolic phenotypes. However, whether tissue context defines cancer dependence on specific metabolic pathways is unknown. Kras activation and Trp53 deletion in the pancreas or the lung result in pancreatic ductal adenocarinoma (PDAC) or non-small cell lung carcinoma (NSCLC), respectively, but despite the same initiating events, these tumors use branched-chain amino acids (BCAAs) differently. NSCLC tumors incorporate free BCAAs into tissue protein and use BCAAs as a nitrogen source, whereas PDAC tumors have decreased BCAA uptake. These differences are reflected in expression levels of BCAA catabolic enzymes in both mice and humans. Loss of Bcat1 and Bcat2, the enzymes responsible for BCAA use, impairs NSCLC tumor formation, but these enzymes are not required for PDAC tumor formation, arguing that tissue of origin is an important determinant of how cancers satisfy their metabolic requirements.

  8. Decreased Consumption of Branched-Chain Amino Acids Improves Metabolic Health.

    PubMed

    Fontana, Luigi; Cummings, Nicole E; Arriola Apelo, Sebastian I; Neuman, Joshua C; Kasza, Ildiko; Schmidt, Brian A; Cava, Edda; Spelta, Francesco; Tosti, Valeria; Syed, Faizan A; Baar, Emma L; Veronese, Nicola; Cottrell, Sara E; Fenske, Rachel J; Bertozzi, Beatrice; Brar, Harpreet K; Pietka, Terri; Bullock, Arnold D; Figenshau, Robert S; Andriole, Gerald L; Merrins, Matthew J; Alexander, Caroline M; Kimple, Michelle E; Lamming, Dudley W

    2016-07-12

    Protein-restricted (PR), high-carbohydrate diets improve metabolic health in rodents, yet the precise dietary components that are responsible for these effects have not been identified. Furthermore, the applicability of these studies to humans is unclear. Here, we demonstrate in a randomized controlled trial that a moderate PR diet also improves markers of metabolic health in humans. Intriguingly, we find that feeding mice a diet specifically reduced in branched-chain amino acids (BCAAs) is sufficient to improve glucose tolerance and body composition equivalently to a PR diet via metabolically distinct pathways. Our results highlight a critical role for dietary quality at the level of amino acids in the maintenance of metabolic health and suggest that diets specifically reduced in BCAAs, or pharmacological interventions in this pathway, may offer a translatable way to achieve many of the metabolic benefits of a PR diet. PMID:27346343

  9. Enhanced production of short-chain fatty acid from food waste stimulated by alkyl polyglycosides and its mechanism.

    PubMed

    Zhao, Jianwei; Yang, Qi; Li, Xiaoming; Wang, Dongbo; Luo, Kun; Zhong, Yu; Xu, Qiuxiang; Zeng, Guangming

    2015-12-01

    Short-chain fatty acids (SCFAs) are the valuable products derived from the anaerobic fermentation of organic solid waste. However, SCFAs yield was limited by the worse solubilization and hydrolysis of particulate organic matter, and rapid consumption of organic acid by methanogens. In this study, an efficient and green strategy, i.e. adding biosurfactant alkyl polyglycosides (APG) into anaerobic fermentation system, was applied to enhance SCFAs production from food waste. Experimental results showed that APG not only greatly improved SCFAs production but also shortened the fermentation time for the maximum SCFAs accumulation. The SCFAs yield at optimal APG dosage 0.2g/g TS (total solid) reached 37.2g/L, which was 3.1-fold of that in blank. Meanwhile, the time to accumulate the maximum SCFAs in the presence of APG was shortened from day 14 to day 6. The activities of key enzymes such as hydrolytic and acid-forming enzymes were greatly promoted due to the presence of APG. These results demonstrated that the enhanced mechanism of SCFAs production should be attributed to the acceleration of solubilization and hydrolysis, enhancement of acidification and inhibition of methanogenesis by APG. PMID:26342451

  10. Enhanced production of short-chain fatty acid from food waste stimulated by alkyl polyglycosides and its mechanism.

    PubMed

    Zhao, Jianwei; Yang, Qi; Li, Xiaoming; Wang, Dongbo; Luo, Kun; Zhong, Yu; Xu, Qiuxiang; Zeng, Guangming

    2015-12-01

    Short-chain fatty acids (SCFAs) are the valuable products derived from the anaerobic fermentation of organic solid waste. However, SCFAs yield was limited by the worse solubilization and hydrolysis of particulate organic matter, and rapid consumption of organic acid by methanogens. In this study, an efficient and green strategy, i.e. adding biosurfactant alkyl polyglycosides (APG) into anaerobic fermentation system, was applied to enhance SCFAs production from food waste. Experimental results showed that APG not only greatly improved SCFAs production but also shortened the fermentation time for the maximum SCFAs accumulation. The SCFAs yield at optimal APG dosage 0.2g/g TS (total solid) reached 37.2g/L, which was 3.1-fold of that in blank. Meanwhile, the time to accumulate the maximum SCFAs in the presence of APG was shortened from day 14 to day 6. The activities of key enzymes such as hydrolytic and acid-forming enzymes were greatly promoted due to the presence of APG. These results demonstrated that the enhanced mechanism of SCFAs production should be attributed to the acceleration of solubilization and hydrolysis, enhancement of acidification and inhibition of methanogenesis by APG.

  11. Melt Rheology of Poly Vinilydene Fluoride: Evidence of Long Chain Branching and Microgel Formation

    NASA Astrophysics Data System (ADS)

    Scanu, Lauriane; Roberts, George W.; DeSimone, Joseph M.; Khan, Saad

    2008-07-01

    Rheological measurements are used to study the influence of molecular weights and molecular weight distributions (MWD) on the melt behavior of poly(vinylidene fluoride) (PVDF). Six commercial PVDF samples with weight-average molecular weight ranging from 139 to 263 kg/mol and polydispersity index ranging from 2.3 to 4 are investigated. The use of van Gurp-Palmen (vGP) plots reveals the presence of long-chain branching (LCB) in three of the samples. They furthermore allow for a qualitative classification of these samples by their LCB degree. The Mark-Houwink relationship between the intrinsic viscosity and weight-average molecular weight is determined and shows no dependence on a low degree of LCB. A similar effect is observed for the flow activation energy which increases linearly with increasing weight-average molecular weight with the exception of the flow activation energy for the highly branched PVDF sample. Samples known to contain microgels are also identifiable by extending the vGP analysis. The generality of this approach is substantiated by removal of the microgel fraction from these samples, which then exhibit conventional melt behavior.

  12. Molecular and phenotypic characteristics of seven novel mutations causing branched-chain organic acidurias.

    PubMed

    Stojiljkovic, M; Klaassen, K; Djordjevic, M; Sarajlija, A; Brasil, S; Kecman, B; Grkovic, S; Kostic, J; Rodriguez-Pombo, P; Desviat, L R; Pavlovic, S; Perez, B

    2016-09-01

    Specific mitochondrial enzymatic deficiencies in the catabolism of branched-chain amino acids cause methylmalonic aciduria (MMA), propionic acidemia (PA) and maple syrup urine disease (MSUD). Disease-causing mutations were identified in nine unrelated branched-chain organic acidurias (BCOA) patients. We detected eight previously described mutations: p.Asn219Tyr, p.Arg369His p.Val553Glyfs*17 in MUT, p.Thr198Serfs*6 in MMAA, p.Ile144_Leu181del in PCCB, p.Gly288Valfs*11, p.Tyr438Asn in BCKDHA and p.Ala137Val in BCKDHB gene. Interestingly, we identified seven novel genetic variants: p.Leu549Pro, p.Glu564*, p.Leu641Pro in MUT, p.Tyr206Cys in PCCB, p.His194Arg, p.Val298Met in BCKDHA and p.Glu286_Met290del in BCKDHB gene. In silico and/or eukaryotic expression studies confirmed pathogenic effect of all novel genetic variants. Aberrant enzymes p.Leu549Pro MUT, p.Leu641Pro MUT and p.Tyr206Cys PCCB did not show residual activity in activity assays. In addition, activity of MUT enzymes was not rescued in the presence of vitamin B12 precursor in vitro which was in accordance with non-responsiveness or partial responsiveness of patients to vitamin B12 therapy. Our study brings the first molecular genetic data and detailed phenotypic characteristics for MMA, PA and MSUD patients for Serbia and the whole South-Eastern European region. Therefore, our study contributes to the better understanding of molecular landscape of BCOA in Europe and to general knowledge on genotype-phenotype correlation for these rare diseases. PMID:26830710

  13. Effects of Branched-chain Amino Acids on In vitro Ruminal Fermentation of Wheat Straw

    PubMed Central

    Zhang, Hui Ling; Chen, Yong; Xu, Xiao Li; Yang, Yu Xia

    2013-01-01

    This study investigates the effects of three branched-chain amino acids (BCAA; valine, leucine, and isoleucine) on the in vitro ruminal fermentation of wheat straw using batch cultures of mixed ruminal microorganisms. BCAA were added to the buffered ruminal fluid at a concentration of 0, 2, 4, 7, or 10 mmol/L. After 72 h of anaerobic incubation, pH, volatile fatty acids (VFA), and ammonia nitrogen (NH3-N) in the ruminal fluid were determined. Dry matter (DM) and neutral detergent fiber (NDF) degradability were calculated after determining the DM and NDF in the original material and in the residue after incubation. The addition of valine, leucine, or isoleucine increased the total VFA yields (p≤0.001). However, the total VFA yields did not increase with the increase of BCAA supplement level. Total branched-chain VFA yields linearly increased as the supplemental amount of BCAA increased (p<0.001). The molar proportions of acetate and propionate decreased, whereas that of butyrate increased with the addition of valine and isoleucine (p<0.05). Moreover, the proportions of propionate and butyrate decreased (p<0.01) with the addition of leucine. Meanwhile, the molar proportions of isobutyrate were increased and linearly decreased (p<0.001) by valine and leucine, respectively. The addition of leucine or isoleucine resulted in a linear (p<0.001) increase in the molar proportions of isovalerate. The degradability of NDF achieved the maximum when valine or isoleucine was added at 2 mmol/L. The results suggest that low concentrations of BCAA (2 mmol/L) allow more efficient regulation of ruminal fermentation in vitro, as indicated by higher VFA yield and NDF degradability. Therefore, the optimum initial dose of BCAA for in vitro ruminal fermentation is 2 mmol/L. PMID:25049818

  14. Benzothiophene carboxylate derivatives as novel allosteric inhibitors of branched-chain α-ketoacid dehydrogenase kinase.

    PubMed

    Tso, Shih-Chia; Gui, Wen-Jun; Wu, Cheng-Yang; Chuang, Jacinta L; Qi, Xiangbing; Skvora, Kristen J; Dork, Kenneth; Wallace, Amy L; Morlock, Lorraine K; Lee, Brendan H; Hutson, Susan M; Strom, Stephen C; Williams, Noelle S; Tambar, Uttam K; Wynn, R Max; Chuang, David T

    2014-07-25

    The mitochondrial branched-chain α-ketoacid dehydrogenase complex (BCKDC) is negatively regulated by reversible phosphorylation.BCKDC kinase (BDK) inhibitors that augment BCKDC flux have been shown to reduce branched-chain amino acid (BCAA) concentrations in vivo. In the present study, we employed high-throughput screens to identify compound 3,6- dichlorobenzo[b]thiophene-2-carboxylic acid (BT2) as a novel BDK inhibitor (IC(50) = 3.19 μM). BT2 binds to the same site in BDK as other known allosteric BDK inhibitors, including (S)-α-cholorophenylproprionate ((S)-CPP). BT2 binding to BDK triggers helix movements in the N-terminal domain, resulting in the dissociation of BDK from the BCKDC accompanied by accelerated degradation of the released kinase in vivo. BT2 shows excellent pharmacokinetics (terminal T(1⁄2) = 730 min) and metabolic stability (no degradation in 240 min), which are significantly better than those of (S)-CPP. BT2, its analog 3-chloro-6-fluorobenzo[ b]thiophene-2-carboxylic acid (BT2F), and a prodrug of BT2 (i.e. N-(4-acetamido-1,2,5-oxadiazol-3-yl)-3,6-dichlorobenzo[ b]thiophene-2-carboxamide (BT3)) significantly increase residual BCKDC activity in cultured cells and primary hepatocytes from patients and a mouse model of maple syrup urine disease. Administration of BT2 at 20 mg/kg/day to wild-type mice for 1 week leads to nearly complete dephosphorylation and maximal activation of BCKDC in heart, muscle, kidneys, and liver with reduction in plasma BCAA concentrations. The availability of benzothiophene carboxylate derivatives as stable BDK inhibitors may prove useful for the treatment of metabolic disease caused by elevated BCAA concentrations. PMID:24895126

  15. Structure-activity relationship of synthetic branched-chain distearoylglycerol (distearin) as protein kinase C activators

    SciTech Connect

    Zhou, Qingzhong; Raynor, R.L.; Wood, M.G. Jr.; Menger, F.M.; Kuo, J.F. )

    1988-09-20

    Several representative branched-chain analogues of distearin (DS) were synthesized and tested for their abilities to activate protein kinase C (PKC) and to compete for the binding of ({sup 3}H)phorbol 12,13-dibutyrate (PDBu) to the enzyme. Substitutions of stearoyl moieties at sn-1 and sn-2 with 8-methylstearate decreased activities on these parameters, relative to those of the parental diacylglycerol DS, a weak PKC activator. Substitutions with 8-butyl, 4-butyl, or 8-phenyl derivatives, on the other hand, increased activities of the resulting analogues to levels comparable to those seen for diolein (DO), a diacylglycerol prototype shown to be a potent PKC activator. Kinetic analysis indicated that 8-methyldistearin (8-MeDS) acted by decreasing, whereas 8-butyldistearin (8-BuDS) and 8-phenyldistearin (8-PhDS) acted by increasing, the affinities of PKC for phosphatidylserine (PS, a phospholipid cofactor) and Ca{sup 2+} compared to the values seen in the absence or presence of DS. The stimulatory effect of 8-BuDS and 8-PhDS on PKC, as DO, was additive to that of 1,2-(8-butyl)distearoylphosphatidylcholine (1,2(8-Bu)DSPC) and, moreover, they abolished the marked inhibition of the enzyme activity caused by high concentrations of 1,2(8-Bu)DSPC. The present findings demonstrated a structure-activity relationship of the branched-chain DS analogues in the regulation of PKC, perhaps related to their abilities to specifically modify interactions of PKC with PS and/or Ca{sup 2+} critically involved in enzyme activation/inactivation.

  16. Murine branched chain alpha-ketoacid dehydrogenase kinase; cDNA cloning, tissue distribution, and temporal expression during embryonic development.

    PubMed

    Doering, C B; Coursey, C; Spangler, W; Danner, D J

    1998-06-01

    These studies were designed to demonstrate the structural and functional similarity of murine branched chain alpha-ketoacid dehydrogenase and its regulation by the complex-specific kinase. Nucleotide sequence and deduced amino acid sequence for the kinase cDNA demonstrate a highly conserved coding sequence between mouse and human. Tissue-specific expression in adult mice parallels that reported in other mammals. Kinase expression in female liver is influenced by circadian rhythm. Of special interest is the fluctuating expression of this kinase during embryonic development against the continuing increase in the catalytic subunits of this mitochondrial complex during development. The need for regulation of the branched chain alpha-ketoacid dehydrogenase complex by kinase expression during embryogenesis is not understood. However, the similarity of murine branched chain alpha-ketoacid dehydrogenase and its kinase to the human enzyme supports the use of this animal as a model for the human system. PMID:9611264

  17. Effect of Sophorolipid n-Alkyl Ester Chain Length on Its Interfacial Properties at the Almond Oil-Water Interface.

    PubMed

    Koh, Amanda; Linhardt, Robert J; Gross, Richard

    2016-06-01

    Sophorolipids (SLs), produced by Candida bombicola, are of interest as potential replacements for hazardous commercial surfactants. For the first time, a series of molecularly edited SLs with ethyl (EE), n-hexyl (HE), and n-decyl (DE) esters were evaluated at an oil (almond oil)-water interface for their ability to reduce interfacial tension (IFT) and generate stable emulsions. An increase in the n-alkyl ester chain length from ethyl to hexyl resulted in a maximum % decrease in the IFT from 86.1 to 95.3, respectively. Furthermore, the critical aggregation concentrations (CACs) decreased from 0.035 to 0.011 and 0.006 mg/mL as the ester chain length was increased from ethyl to n-hexyl and n-decyl, respectively. In contrast, the CAC of natural SL, composed of 50/50 acidic and LSL, is 0.142 mg/mL. Dynamic IFT analysis showed significant differences in diffusion coefficients for all SLs studied. Almond oil emulsions with up to 200:1 (by weight) oil/SL-DE were stable against oil separation for up to 1 week with average droplet sizes below 5 μm. Emulsions of almond oil with natural SLs showed consistent oil separation 24 h after emulsification. A unique connection between IFT and emulsification was found as SL-DE has both the lowest CAC and the best emulsification performance of all natural and modified SLs studied herein. This connection between CAC and emulsification may be generally applicable, providing a tool for the prediction of optimal surfactants in other oil-water interfacial applications. PMID:27159768

  18. Rheological properties of long-chain branched chlorinated poly(isobutylene-co-isoprene)-graft-polybutadiene terpolymers (CIIR-g-BR)

    NASA Astrophysics Data System (ADS)

    Sendorek, Jerzy (George)

    Anionically polymerized "living" polybutadiene (BR) was grafted onto chlorinated poly(isobutylene-co-isoprene) (CIIR) to form a series of elastomeric graft copolymers (CIIR-g-BR) of comb-type, long-chain branching structure (LCB) with systematically varying length and number of branches. A comprehensive program of analytical characterization of the structure and morphology of these materials using SEC/DRI-DV, NMR, FT-IR, DSC, TGA, TEM and other techniques, was designed to determine all relevant structural variables and parameters, as well as to exclude the presence of the potential compositional interferences (gel, residual solvent, unattached branch parent polymer, etc.) for intended correlations between branching structure and rheological properties. The principal branching characteristics of comb-like long-chain branched structures were derived from the stoichiometry of the grafting reaction, confirmed by compositional analysis using a combination of NMR/FT-IR/SEC and supplemented by SEC characterization of the parent linear polymers constituting the backbone (CIIR) and the branch of the graft (BR), respectively. Linear viscoelastic properties of these materials were determined by a Rheometrics Mechanical Spectrometer (RMS-800) using small amplitude, dynamic (sinusoidal oscillatory) shear. These measurements were supplemented by Rubber Process Analyzer (RPA 2000sp{TM}) testing in a comparable range of strain amplitudes, frequencies and temperatures. Stress relaxation experiments, following small amplitude step-strain in shear, complemented the dynamic mechanical measurement. Non-linear viscoelastic properties in shear were investigated in a series of isothermal strain and frequency sweeps using large strain (up to 800%) oscillations (RPA 2000), and by stress following a large-amplitude (˜75%) step shear strain, using the Dynamic Stress Relaxometer (DSR). An insight into the morphology of the grafts by means of the TEM and DSC has been compared to the results of

  19. Demonstration of long-chain n-alkyl caffeates and delta7-steryl glucosides in the bark of Acacia species by gas chromatography-mass spectrometry.

    PubMed

    Freire, Carmen S R; Silvestre, Armando J D; Neto, Carlos Pascoal

    2007-01-01

    The GC-MS identification of several abundant long-chain aliphatic n-alkyl caffeates, together with other phydroxycinnamic acid esters, in the dichloromethane extracts of the bark of Acacia dealbata and A. melanoxylon, is reported. In addition, the unambiguous differentiation between two delta7-steryl glucosides (namely, spinasteryl glucoside and dihydrospinasteryl glucosides) and the homologous delta5-steryl glucosides was achieved based on the EI-MS fragmentation features of their trimethylsilyl derivatives. PMID:17439016

  20. Cu sbnd Al sbnd Fe layered double hydroxides with CO32- and anionic surfactants with different alkyl chains in the interlayer

    NASA Astrophysics Data System (ADS)

    Trujillano, Raquel; Holgado, María Jesús; González, José Luis; Rives, Vicente

    2005-08-01

    Layered double hydroxides (LDHs), with the hydrotalcite-like structure containing Cu(II), Al(III) and Fe(III) in the layers, and different alkyl sulfonates in the interlayer, have been prepared and characterized by powder X-ray diffraction, FT-IR spectroscopy, differential thermal analysis and thermogravimetric analysis. Pure crystalline phases have been obtained in all cases. Upon heating, combustion of the organic chain takes place at lower temperature than the corresponding sodium salts.

  1. Structural and Rotational Dynamics of Carbon Dioxide in 1-Alkyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquids: The Effect of Chain Length.

    PubMed

    Giammanco, Chiara H; Yamada, Steven A; Kramer, Patrick L; Tamimi, Amr; Fayer, Michael D

    2016-07-14

    Ionic liquids (ILs) have been proposed as possible carbon dioxide (CO2) capture media; thus, it is useful to understand the dynamics of both the dissolved gas and its IL environment as well as how altering an IL affects these dynamics. With increasing alkyl chain length, it is well-established that ILs obtain a mesoscopic structural feature assigned to polar-apolar segregation, and the change in structure with chain length affects the dynamics. Here, the dynamics of CO2 in a series of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ILs, in which the alkyl group is ethyl, butyl, hexyl, or decyl, were investigated using ultrafast infrared spectroscopy by measuring the reorientation and spectral diffusion of carbon dioxide in the ILs. It was found that reorientation of the carbon dioxide occurs on three time scales, which correspond to two different time scales of restricted wobbling-in-a-cone motions and a long-time complete diffusive reorientation. Complete reorientation slows with increasing chain length but less than the increases in viscosity of the bulk liquids. Spectral diffusion, measured with two-dimensional IR spectroscopy, is caused by a combination of the liquids' structural fluctuations and reorientation of the CO2. The data were analyzed using a recent theory that takes into account both contributions to spectral diffusion and extracts the structural spectral diffusion. Different components of the structural fluctuations have distinct dependences on the alkyl chain length. All of the dynamics are fast compared to the complete orientational randomization of the bulk ILs, as measured with optical heterodyne-detected optical Kerr effect measurements. The results indicate a hierarchy of constraint releases in the liquids that give rise to increasingly slower dynamics. PMID:27264965

  2. Branched-chain amino acid catabolism fuels adipocyte differentiation and lipogenesis.

    PubMed

    Green, Courtney R; Wallace, Martina; Divakaruni, Ajit S; Phillips, Susan A; Murphy, Anne N; Ciaraldi, Theodore P; Metallo, Christian M

    2016-01-01

    Adipose tissue plays important roles in regulating carbohydrate and lipid homeostasis, but less is known about the regulation of amino acid metabolism in adipocytes. Here we applied isotope tracing to pre-adipocytes and differentiated adipocytes to quantify the contributions of different substrates to tricarboxylic acid (TCA) metabolism and lipogenesis. In contrast to proliferating cells, which use glucose and glutamine for acetyl-coenzyme A (AcCoA) generation, differentiated adipocytes showed increased branched-chain amino acid (BCAA) catabolic flux such that leucine and isoleucine from medium and/or from protein catabolism accounted for as much as 30% of lipogenic AcCoA pools. Medium cobalamin deficiency caused methylmalonic acid accumulation and odd-chain fatty acid synthesis. Vitamin B12 supplementation reduced these metabolites and altered the balance of substrates entering mitochondria. Finally, inhibition of BCAA catabolism compromised adipogenesis. These results quantitatively highlight the contribution of BCAAs to adipocyte metabolism and suggest that BCAA catabolism has a functional role in adipocyte differentiation. PMID:26571352

  3. Branched Chain Fatty Acid (BCFA) Content of Foods and Estimated Intake in the United States

    PubMed Central

    Bae, SangEun; Lawrence, Peter; Wang, Dong Hao

    2015-01-01

    Branched chain fatty acids (BCFA) are bioactive food components that constitute about 2% of fatty acids in cow’s milk fat. Little systematic information on the BCFA content of other foods is available to estimate dietary intakes. We report BCFA distribution and content of fresh and processed foods representing the major foods of Americans and estimate BCFA intake. BCFA are primarily components of dairy and ruminant foods, and were absent from chicken, pork, and salmon. Dairy and beef delivered most of the 500 mg per day mean intake; in comparison, intake of the widely studied long chain polyunsaturates eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is estimated to average 100 mg per day. Common adjustments in diet can double BCFA daily intake. The fermented foods sauerkraut and miso had appreciable fractions of BCFA but overall are low fat foods providing very small amounts in the diet, and other fermented foods did not contain BCFA as might have been expected from microbial exposure. These data support the quantitative importance of BCFA delivered primarily from dairy and beef and highlight the need for research into their health effects. PMID:24830474

  4. Comparative studies of Acyl-CoA dehydrogenases for monomethyl branched chain substrates in amino acid metabolism.

    PubMed

    Liu, Xiaojun; Wu, Long; Deng, Guisheng; Chen, Gong; Li, Nan; Chu, Xiusheng; Li, Ding

    2013-04-01

    Short/branched chain acyl-CoA dehydrogenase (SBCAD), isovaleryl-CoA dehydrogenase (IVD), and isobutyryl-CoA dehydrogenase (IBD) are involved in metabolism of isoleucine, leucine, and valine, respectively. These three enzymes all belong to acyl-CoA dehydrogenase (ACD) family, and catalyze the dehydrogenation of monomethyl branched-chain fatty acid (mmBCFA) thioester derivatives. In the present work, the catalytic properties of rat SBCAD, IVD, and IBD, including their substrate specificity, isomerase activity, and enzyme inhibition, were comparatively studied. Our results indicated that SBCAD has its catalytic properties relatively similar to those of straight-chain acyl-CoA dehydrogenases in terms of their isomerase activity and enzyme inhibition, while IVD and IBD are different. IVD has relatively broader substrate specificity than those of the other two enzymes in accommodating various substrate analogs. The present study increased our understanding for the metabolism of monomethyl branched-chain fatty acids (mmBCFAs) and branched-chain amino acids (BCAAs), which should also be useful for selective control of a particular reaction through the design of specific inhibitors. PMID:23474214

  5. Investigation of double bond conversion, mechanical properties, and antibacterial activity of dental resins with different alkyl chain length quaternary ammonium methacrylate monomers (QAM).

    PubMed

    He, Jingwei; Söderling, Eva; Vallittu, Pekka K; Lassila, Lippo V J

    2013-01-01

    In order to endow dental resin with antibacterial activity, a series of antibacterial quaternary ammonium methacrylate monomers (QAM) with different substituted alkyl chain length (from 10 to 18) were incorporated into commonly used 2,2-bis[4-(2'-hydroxy-3'-methacryloyloxy-propoxy)-phenyl]propane (Bis-GMA)/triethyleneglycol dimethacrylate (TEGDMA) (50 wt/50 wt) dental resin as immobilized antibacterial agents. Double bond conversion (DC), flexural strength (FS) and modulus (FM), and young and mature biofilms inhibition effectiveness of prepared dental resins were studied and Bis-GMA/TEGDMA without QAM was used as reference. Results showed that there was no significant difference on DC, FS, and FM between copolymer with and without 5 wt% QAM. Substituted alkyl chain length of QAM had no influence on DC, FS, and FM of copolymer, but had influence on antibacterial activity of copolymer. Antibacterial activity of copolymer increased with increasing of substituted alkyl chain length of QAM, and the sequence followed as 5%C10 < 5%C11 ≈ 5%C12 < 5%C16 ≈ 5%C18. Copolymers containing C18 and C16 had the best inhibition effectiveness on both young biofilm and mature biofilm, copolymers containing C12 and C11 only had inhibition effectiveness on young biofilm and copolymer containing C10 had none inhibition effectiveness on neither young biofilm nor mature biofilm.

  6. Prediction and determination of the stereochemistry of the 1,3,5-trimethyl-substituted alkyl chain in verucopeptin, a microbial metabolite.

    PubMed

    Yoshimura, Aya; Kishimoto, Shinji; Nishimura, Shinichi; Otsuka, Saori; Sakai, Yuki; Hattori, Akira; Kakeya, Hideaki

    2014-08-01

    For the prediction of the relative stereochemistry of 1,3-dimethyl substitution in alkyl chains, a simple approach based on (1)H NMR data was recently proposed; Δδ values of methylene protons located between methyl-substituted methine carbons can be diagnostic for predicting it. Here we applied this empirical "geminal proton rule" to verucopeptin, a lipopeptide from Streptomyces sp. To determine the absolute stereochemistry of the 1,3,5-trimethyl-substituted alkyl chain in verucopeptin, we converted the corresponding alkyl chain to a carboxylic acid by oxidative cleavage. The geminal proton rule clearly predicted the relative stereochemistry as 31S*,33S*,35R*. This prediction was definitely confirmed by synthesizing four possible diastereomers and comparing their NMR spectra. Furthermore, we reinvestigated the geminal proton rule using reported compounds and our synthesized compounds. Our result strongly suggests that the rule was solid, at least for predicting the stereochemistry of 2,4-dimethylated and 2,4,6-trimethylated fatty acids.

  7. Chain architecture and micellization: A mean-field coarse-grained model for poly(ethylene oxide) alkyl ether surfactants

    NASA Astrophysics Data System (ADS)

    García Daza, Fabián A.; Colville, Alexander J.; Mackie, Allan D.

    2015-03-01

    Microscopic modeling of surfactant systems is expected to be an important tool to describe, understand, and take full advantage of the micellization process for different molecular architectures. Here, we implement a single chain mean field theory to study the relevant equilibrium properties such as the critical micelle concentration (CMC) and aggregation number for three sets of surfactants with different geometries maintaining constant the number of hydrophobic and hydrophilic monomers. The results demonstrate the direct effect of the block organization for the surfactants under study by means of an analysis of the excess energy and entropy which can be accurately determined from the mean-field scheme. Our analysis reveals that the CMC values are sensitive to branching in the hydrophilic head part of the surfactant and can be observed in the entropy-enthalpy balance, while aggregation numbers are also affected by splitting the hydrophobic tail of the surfactant and are manifested by slight changes in the packing entropy.

  8. Chain architecture and micellization: A mean-field coarse-grained model for poly(ethylene oxide) alkyl ether surfactants

    SciTech Connect

    García Daza, Fabián A.; Mackie, Allan D.; Colville, Alexander J.

    2015-03-21

    Microscopic modeling of surfactant systems is expected to be an important tool to describe, understand, and take full advantage of the micellization process for different molecular architectures. Here, we implement a single chain mean field theory to study the relevant equilibrium properties such as the critical micelle concentration (CMC) and aggregation number for three sets of surfactants with different geometries maintaining constant the number of hydrophobic and hydrophilic monomers. The results demonstrate the direct effect of the block organization for the surfactants under study by means of an analysis of the excess energy and entropy which can be accurately determined from the mean-field scheme. Our analysis reveals that the CMC values are sensitive to branching in the hydrophilic head part of the surfactant and can be observed in the entropy-enthalpy balance, while aggregation numbers are also affected by splitting the hydrophobic tail of the surfactant and are manifested by slight changes in the packing entropy.

  9. 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

    2015-02-01

    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.

  10. Enhancement of endotoxin neutralization by coupling of a C12-alkyl chain to a lactoferricin-derived peptide

    PubMed Central

    2004-01-01

    Antibacterial peptide acylation, which mimics the structure of the natural lipopeptide polymyxin B, increases antimicrobial and endotoxin-neutralizing activities. The interaction of the lactoferricin-derived peptide LF11 and its N-terminally acylated analogue, lauryl-LF11, with different chemotypes of bacterial lipopolysaccharide (LPS Re, Ra and smooth S form) was investigated by biophysical means and was related to the peptides' biological activities. Both peptides exhibit high antibacterial activity against the three strains of Salmonella enterica differing in the LPS chemotype. Lauryl-LF11 has one order of magnitude higher activity against Re-type, but activity against Ra- and S-type bacteria is comparable with that of LF11. The alkyl derivative peptide lauryl-LF11 shows a much stronger inhibition of the LPS-induced cytokine induction in human mononuclear cells than LF11. Although peptide–LPS interaction is essentially of electrostatic nature, the lauryl-modified peptide displays a strong hydrophobic component. Such a feature might then explain the fact that saturation of the peptide binding takes place at a much lower peptide/LPS ratio for LF11 than for lauryl-LF11, and that an overcompensation of the negative LPS backbone charges is observed for lauryl-LF11. The influence of LF11 on the gel-to-liquid-crystalline phase-transition of LPS is negligible for LPS Re, but clearly fluidizing for LPS Ra. In contrast, lauryl-LF11 causes a cholesterol-like effect in the two chemotypes, fluidizing in the gel and rigidifying of the hydrocarbon chains in the liquid-crystalline phase. Both peptides convert the mixed unilamellar/non-lamellar aggregate structure of lipid A, the ‘endotoxic principle’ of LPS, into a multilamellar one. These data contribute to the understanding of the mechanisms of the peptide-mediated neutralization of endotoxin and effect of lipid modification of peptides. PMID:15344905

  11. Regulation of adipose branched chain amino acid catabolism enzyme expression and cross-adipose amino acid flux in human obesity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elevated blood branched chain amino acids (BCAA) are often associated with insulin resistance and type 2 diabetes. One possibility is that under these conditions there is a reduced cellular utilization and/or lower complete oxidation of BCAAs. White adipose tissue (WAT) has become appreciated as a...

  12. The dietary branched chain amino acid requirements of hybrid striped bass(Morone chrysops x M. saxatilis)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The requirements for branched chain amino acids (BCAAs) are unknown in hybrid striped bass and necessary for formulating efficient and nutritious diets. Moreover, the dietary balance among these three amino acids can substantially influence the performance of meat animals fed those diets. The diet...

  13. Supplemental branched-chain amino acids improve performance and immune response of newly-received feedlot calves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Supplemental branched-chain AA (BCAA) improved N balance of steers during a simulated pathogen challenge. The objective of this study was to determine the effect of supplemental BCAA on growth and health of newly-received feedlot steers. Steers (n = 120; initial BW = 376 ± 5 kg) were blocked by BW a...

  14. Glucose supplementation stimulates peripheral branched-chain amino acid catabolism in lactating dairy cows during essential amino acid infusions.

    PubMed

    Nichols, K; Kim, J J M; Carson, M; Metcalf, J A; Cant, J P; Doelman, J

    2016-02-01

    To determine how glucose modulates protein synthesis when essential AA are in abundant supply, 5 early-lactation, rumen-fistulated Holstein dairy cows were fed a diet containing 6.95 MJ/kg of net energy for lactation and 12.4% crude protein and abomasally infused for 5 d with saline, 844 or 1,126 g/d of a complete essential AA mix, with and without the inclusion of 1,000 g/d of glucose, in a 5×5 Latin square design. Infusion of essential AA increased milk yield by 4.1 kg/d, milk protein by 256 g/d, milk fat by 95 g/d, and milk urea nitrogen by 70% compared with saline, with no differences between the level of essential AA infusion. The addition of glucose to essential AA infusate did not stimulate milk protein yield or concentration, but reduced milk urea nitrogen by 17% and decreased milk fat yield. Arterial concentrations of total essential AA increased 3- to 4-fold, mammary clearance decreased 61%, and mammary uptake of essential AA increased 65% in response to essential AA infusion. Arterial branched-chain AA concentrations declined 29% in response to glucose and mammary clearance increased 48%, but mammary AA uptake was unchanged. Essential AA infusion increased plasma 3-methylhistidine by 50% and reduced muscle branched-chain α-keto acid dehydrogenase kinase abundance by 14%, indicating stimulation of muscle protein turnover and branched-chain AA catabolism, respectively. Glucose had no further effect on muscle branched-chain α-keto acid dehydrogenase kinase abundance but decreased mRNA expression of branched chain aminotransferase 1. Lack of further increases in plasma 3-methylhistidine or greater stimulation of muscle branched-chain AA catabolism indicates that muscle protein degradation was unchanged with glucose but that accretion may have been stimulated. The decrease in circulating branched-chain AA concentrations and nitrogen excretion in response to glucose suggests that surplus essential AA were redirected to peripheral, extra-mammary tissues.

  15. Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity

    SciTech Connect

    Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit

    2014-03-14

    Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH{sub 2} + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH{sub 2}) considered are acetamide (CH{sub 3}CONH{sub 2}), propionamide (CH{sub 3}CH{sub 2}CONH{sub 2}), and butyramide (CH{sub 3}CH{sub 2}CH{sub 2}CONH{sub 2}); the electrolytes (LiX) are lithium perchlorate (LiClO{sub 4}), lithium bromide (LiBr), and lithium nitrate (LiNO{sub 3}). Differential scanning calorimetric measurements reveal glass transition temperatures (T{sub g}) of these DEs are ∼195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady state fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ∼100–150 K above their individual T{sub g}s. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH{sub 3}CONH{sub 2} + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in

  16. Comparative Genomics of Syntrophic Branched-Chain Fatty Acid Degrading Bacteria

    PubMed Central

    Narihiro, Takashi; Nobu, Masaru K.; Tamaki, Hideyuki; Kamagata, Yoichi; Sekiguchi, Yuji; Liu, Wen-Tso

    2016-01-01

    The syntrophic degradation of branched-chain fatty acids (BCFAs) such as 2-methylbutyrate and isobutyrate is an essential step in the production of methane from proteins/amino acids in anaerobic ecosystems. While a few syntrophic BCFA-degrading bacteria have been isolated, their metabolic pathways in BCFA and short-chain fatty acid (SCFA) degradation as well as energy conservation systems remain unclear. In an attempt to identify these pathways, we herein performed comparative genomics of three syntrophic bacteria: 2-methylbutyrate-degrading “Syntrophomonas wolfei subsp. methylbutyratica” strain JCM 14075T (=4J5T), isobutyrate-degrading Syntrophothermus lipocalidus strain TGB-C1T, and non-BCFA-metabolizing S. wolfei subsp. wolfei strain GöttingenT. We demonstrated that 4J5 and TGB-C1 both encode multiple genes/gene clusters involved in β-oxidation, as observed in the Göttingen genome, which has multiple copies of genes associated with butyrate degradation. The 4J5 genome possesses phylogenetically distinct β-oxidation genes, which may be involved in 2-methylbutyrate degradation. In addition, these Syntrophomonadaceae strains harbor various hydrogen/formate generation systems (i.e., electron-bifurcating hydrogenase, formate dehydrogenase, and membrane-bound hydrogenase) and energy-conserving electron transport systems, including electron transfer flavoprotein (ETF)-linked acyl-CoA dehydrogenase, ETF-linked iron-sulfur binding reductase, ETF dehydrogenase (FixABCX), and flavin oxidoreductase-heterodisulfide reductase (Flox-Hdr). Unexpectedly, the TGB-C1 genome encodes a nitrogenase complex, which may function as an alternative H2 generation mechanism. These results suggest that the BCFA-degrading syntrophic strains 4J5 and TGB-C1 possess specific β-oxidation-related enzymes for BCFA oxidation as well as appropriate energy conservation systems to perform thermodynamically unfavorable syntrophic metabolism. PMID:27431485

  17. Production of C4 and C5 branched-chain alcohols by engineered Escherichia. coli.

    PubMed

    Chen, Xiaoyan; Xu, Jingliang; Yang, Liu; Yuan, Zhenhong; Xiao, Shiyuan; Zhang, Yu; Liang, Cuiyi; He, Minchao; Guo, Ying

    2015-11-01

    Higher alcohols, longer chain alcohols, contain more than 3 carbon atoms, showed close energy advantages as gasoline, and were considered as the next generation substitution for chemical fuels. Higher alcohol biosynthesis by native microorganisms mainly needs gene expression of heterologous keto acid decarboxylase and alcohol dehydrogenases. In the present study, branched-chain α-keto acid decarboxylase gene from Lactococcus lactis subsp. lactis CICC 6246 (Kivd) and alcohol dehydrogenases gene from Zymomonas mobilis CICC 41465 (AdhB) were transformed into Escherichia coli for higher alcohol production. SDS-PAGE results showed these two proteins were expressed in the recombinant strains. The resulting strain was incubated in LB medium at 37 °C in Erlenmeyer flasks and much more 3-methyl-1-butanol (104 mg/L) than isobutanol (24 mg/L) was produced. However, in 5 g/L glucose-containing medium, the production of two alcohols was similar, 156 and 161 mg/L for C4 (isobutanol) and C5 (3-methyl-1-butanol) alcohol, respectively. Effects of fermentation factors including temperature, glucose content, and α-keto acid on alcohol production were also investigated. The increase of glucose content and the adding of α-keto acids facilitated the production of C4 and C5 alcohols. The enzyme activities of pure Kivd on α-ketoisovalerate and α-ketoisocaproate were 26.77 and 21.24 μmol min(-1) mg(-1), respectively. Due to its ability on decarboxylation of α-ketoisovalerate and α-ketoisocaproate, the recombinant E. coli strain showed potential application on isoamyl alcohol and isobutanol production.

  18. Catabolism of Branched Chain Amino Acids Contributes Significantly to Synthesis of Odd-Chain and Even-Chain Fatty Acids in 3T3-L1 Adipocytes.

    PubMed

    Crown, Scott B; Marze, Nicholas; Antoniewicz, Maciek R

    2015-01-01

    The branched chain amino acids (BCAA) valine, leucine and isoleucine have been implicated in a number of diseases including obesity, insulin resistance, and type 2 diabetes mellitus, although the mechanisms are still poorly understood. Adipose tissue plays an important role in BCAA homeostasis by actively metabolizing circulating BCAA. In this work, we have investigated the link between BCAA catabolism and fatty acid synthesis in 3T3-L1 adipocytes using parallel 13C-labeling experiments, mass spectrometry and model-based isotopomer data analysis. Specifically, we performed parallel labeling experiments with four fully 13C-labeled tracers, [U-13C]valine, [U-13C]leucine, [U-13C]isoleucine and [U-13C]glutamine. We measured mass isotopomer distributions of fatty acids and intracellular metabolites by GC-MS and analyzed the data using the isotopomer spectral analysis (ISA) framework. We demonstrate that 3T3-L1 adipocytes accumulate significant amounts of even chain length (C14:0, C16:0 and C18:0) and odd chain length (C15:0 and C17:0) fatty acids under standard cell culture conditions. Using a novel GC-MS method, we demonstrate that propionyl-CoA acts as the primer on fatty acid synthase for the production of odd chain fatty acids. BCAA contributed significantly to the production of all fatty acids. Leucine and isoleucine contributed at least 25% to lipogenic acetyl-CoA pool, and valine and isoleucine contributed 100% to lipogenic propionyl-CoA pool. Our results further suggest that low activity of methylmalonyl-CoA mutase and mass action kinetics of propionyl-CoA on fatty acid synthase result in high rates of odd chain fatty acid synthesis in 3T3-L1 cells. Overall, this work provides important new insights into the connection between BCAA catabolism and fatty acid synthesis in adipocytes and underscores the high capacity of adipocytes for metabolizing BCAA.

  19. Catabolism of Branched Chain Amino Acids Contributes Significantly to Synthesis of Odd-Chain and Even-Chain Fatty Acids in 3T3-L1 Adipocytes.

    PubMed

    Crown, Scott B; Marze, Nicholas; Antoniewicz, Maciek R

    2015-01-01

    The branched chain amino acids (BCAA) valine, leucine and isoleucine have been implicated in a number of diseases including obesity, insulin resistance, and type 2 diabetes mellitus, although the mechanisms are still poorly understood. Adipose tissue plays an important role in BCAA homeostasis by actively metabolizing circulating BCAA. In this work, we have investigated the link between BCAA catabolism and fatty acid synthesis in 3T3-L1 adipocytes using parallel 13C-labeling experiments, mass spectrometry and model-based isotopomer data analysis. Specifically, we performed parallel labeling experiments with four fully 13C-labeled tracers, [U-13C]valine, [U-13C]leucine, [U-13C]isoleucine and [U-13C]glutamine. We measured mass isotopomer distributions of fatty acids and intracellular metabolites by GC-MS and analyzed the data using the isotopomer spectral analysis (ISA) framework. We demonstrate that 3T3-L1 adipocytes accumulate significant amounts of even chain length (C14:0, C16:0 and C18:0) and odd chain length (C15:0 and C17:0) fatty acids under standard cell culture conditions. Using a novel GC-MS method, we demonstrate that propionyl-CoA acts as the primer on fatty acid synthase for the production of odd chain fatty acids. BCAA contributed significantly to the production of all fatty acids. Leucine and isoleucine contributed at least 25% to lipogenic acetyl-CoA pool, and valine and isoleucine contributed 100% to lipogenic propionyl-CoA pool. Our results further suggest that low activity of methylmalonyl-CoA mutase and mass action kinetics of propionyl-CoA on fatty acid synthase result in high rates of odd chain fatty acid synthesis in 3T3-L1 cells. Overall, this work provides important new insights into the connection between BCAA catabolism and fatty acid synthesis in adipocytes and underscores the high capacity of adipocytes for metabolizing BCAA. PMID:26710334

  20. Catabolism of Branched Chain Amino Acids Contributes Significantly to Synthesis of Odd-Chain and Even-Chain Fatty Acids in 3T3-L1 Adipocytes

    PubMed Central

    Crown, Scott B.; Marze, Nicholas; Antoniewicz, Maciek R.

    2015-01-01

    The branched chain amino acids (BCAA) valine, leucine and isoleucine have been implicated in a number of diseases including obesity, insulin resistance, and type 2 diabetes mellitus, although the mechanisms are still poorly understood. Adipose tissue plays an important role in BCAA homeostasis by actively metabolizing circulating BCAA. In this work, we have investigated the link between BCAA catabolism and fatty acid synthesis in 3T3-L1 adipocytes using parallel 13C-labeling experiments, mass spectrometry and model-based isotopomer data analysis. Specifically, we performed parallel labeling experiments with four fully 13C-labeled tracers, [U-13C]valine, [U-13C]leucine, [U-13C]isoleucine and [U-13C]glutamine. We measured mass isotopomer distributions of fatty acids and intracellular metabolites by GC-MS and analyzed the data using the isotopomer spectral analysis (ISA) framework. We demonstrate that 3T3-L1 adipocytes accumulate significant amounts of even chain length (C14:0, C16:0 and C18:0) and odd chain length (C15:0 and C17:0) fatty acids under standard cell culture conditions. Using a novel GC-MS method, we demonstrate that propionyl-CoA acts as the primer on fatty acid synthase for the production of odd chain fatty acids. BCAA contributed significantly to the production of all fatty acids. Leucine and isoleucine contributed at least 25% to lipogenic acetyl-CoA pool, and valine and isoleucine contributed 100% to lipogenic propionyl-CoA pool. Our results further suggest that low activity of methylmalonyl-CoA mutase and mass action kinetics of propionyl-CoA on fatty acid synthase result in high rates of odd chain fatty acid synthesis in 3T3-L1 cells. Overall, this work provides important new insights into the connection between BCAA catabolism and fatty acid synthesis in adipocytes and underscores the high capacity of adipocytes for metabolizing BCAA. PMID:26710334

  1. Production of volatile compounds by Lactobacillus sakei from branched chain α-keto acids.

    PubMed

    Gutsche, K Amelie; Tran, Thi Bich Thao; Vogel, Rudi F

    2012-04-01

    Lactobacillus sakei belongs to the main flora of raw fermented sausages and is used as starter culture. Bacterial starter cultures can convert amino acids to α-keto acids by aminotransferases. These α-keto acids are the precursors of aroma active aldehydes, alcohols and carboxylic acids. In this study the formation of aldehydes, alcohols and carboxylic acids from leucine, isoleucine, valine and the corresponding α-keto acids are analysed in model fermentations with two different strains of L sakei. In the absence and upon addition of leucine, isoleucine and valine they produced 1 μg/ml 3-methylbutanoic, 0.2 μg/ml 2-methylbutanoic acid and 3 μg/ml 2-methylpropanoic acid, respectively. Upon addition of α-ketoisocaproic acid, α-keto-3-methyl-pentanoic acid or α-ketoisovaleric acid the amount of the corresponding carboxylic acid was increased to 40 μg/ml 3-methylbutanoic acid, 20 μg/ml 2-methylbutanoic acid and 35 μg/ml 2-methylpropanoic acid. The response patterns of the strains and amounts of carboxylic acids produced were similar. This behaviour was typical when compared with other strains of L. sakei and suggests general lack of transaminase activity and a limit in the transport of branched chain amino acids and their conversion to volatiles, some of which can contribute to the aroma of fermented sausages.

  2. Nutritional treatment with branched-chain amino acids in advanced liver cirrhosis.

    PubMed

    Marchesini, G; Bianchi, G; Rossi, B; Brizi, M; Melchionda, N

    2000-01-01

    During the last 20 years there has been much interest in nutritional treatment for patients with advanced cirrhosis. Most studies have measured the potential benefit of nutritional supplements of dietary proteins, generic protein hydrolysates, or specific branched-chain amino acid (BCAA)-enriched formulas in regard to nutritional parameters and hepatic encephalopathy. The issue is not definitively settled; data are conflicting and meta-analyses have failed to produce unequivocal results. A consensus review, recently produced under the auspices of the European Society for Parenteral and Enteral Nutrition, concluded that: (1) patients with cirrhosis tend to be hypermetabolic, and a higher-than-normal supply of dietary proteins is needed to achieve nitrogen balance; (2) most patients tolerate a normal or even increased dietary protein intake, without risk of hepatic encephalopathy; (3) a modified eating pattern, based on several meals and a late evening snack, is useful; (4) in severely malnourished patients, amino acid supplements may be considered to provide the necessary amount of proteins to meet protein requirements; (5) in a few patients intolerant to the required protein intake, BCAA supplements may be considered to provide the necessary nitrogen intake without detrimental effects on the mental state, perhaps even improving it. Future studies are needed to quantify the advantage of nutritional support with amino acids or BCAA supplements on overall well-being, complications, and ultimately survival with a long-lasting disease where self-perceived health-related quality of life is a major outcome.

  3. A branched chain amino acid metabolite drives vascular transport of fat and causes insulin resistance

    PubMed Central

    Jang, Cholsoon; Oh, Sungwhan F; Wada, Shogo; Rowe, Glenn C; Liu, Laura; Chan, Mun Chun; Rhee, James; Hoshino, Atsushi; Kim, Boa; Ibrahim, Ayon; Baca, Luisa G; Kim, Esl; Ghosh, Chandra C; Parikh, Samir M; Jiang, Aihua; Chu, Qingwei; Forman, Daniel E.; Lecker, Stewart H.; Krishnaiah, Saikumari; Rabinowitz, Joshua D; Weljie, Aalim M; Baur, Joseph A; Kasper, Dennis L; Arany, Zoltan

    2016-01-01

    Epidemiological and experimental data implicate branched chain amino acids (BCAAs) in the development of insulin resistance, but the mechanisms underlying this link remain unclear.1–3 Insulin resistance in skeletal muscle stems from excess accumulation of lipid species4, a process that requires blood-borne lipids to first traverse the blood vessel wall. Little is known, however, of how this trans-endothelial transport occurs or is regulated. Here, we leverage PGC-1α, a transcriptional coactivator that regulates broad programs of FA consumption, to identify 3-hydroxy-isobutyrate (3-HIB), a catabolic intermediate of the BCAA valine, as a novel paracrine regulator of trans-endothelial fatty acids (FA) transport. 3-HIB is secreted from muscle cells, activates endothelial FA transport, stimulates muscle FA uptake in vivo, and promotes muscle lipid accumulation and insulin resistance in animals. Conversely, inhibiting the synthesis of 3-HIB in muscle cells blocks the promotion of endothelial FA uptake. 3-HIB levels are elevated in muscle from db/db mice and from subjects with diabetes. These data thus unveil a novel mechanism that regulates trans-endothelial flux of FAs, revealing 3-HIB as a new bioactive signaling metabolite that links the regulation of FA flux to BCAA catabolism and provides a mechanistic explanation for how increased BCAA catabolic flux can cause diabetes. PMID:26950361

  4. Three targets of branched-chain amino acid supplementation in the treatment of liver disease.

    PubMed

    Holecek, Milan

    2010-05-01

    The article explains the pathogenesis of disturbances in branched-chain amino acid (BCAA; valine, leucine, and isoleucine) and protein metabolism in various forms of hepatic injury and it is suggested that the main cause of decrease in plasma BCAA concentration in liver cirrhosis is hyperammonemia. Three possible targets of BCAA supplementation in hepatic disease are suggested: (1) hepatic encephalopathy, (2) liver regeneration, and (3) hepatic cachexia. The BCAA may ameliorate hepatic encephalopathy by promoting ammonia detoxification, correction of the plasma amino acid imbalance, and by reduced brain influx of aromatic amino acids. The influence of BCAA supplementation on hepatic encephalopathy could be more effective in chronic hepatic injury with hyperammonemia and low concentrations of BCAA in blood than in acute hepatic illness, where hyperaminoacidemia frequently develops. The favorable effect of BCAA on liver regeneration and nutritional state of the body is related to their stimulatory effect on protein synthesis, secretion of hepatocyte growth factor, glutamine production and inhibitory effect on proteolysis. Presumably the beneficial effect of BCAA on hepatic cachexia is significant in compensated liver disease with decreased plasma BCAA concentrations, whereas it is less pronounced in hepatic diseases with inflammatory complications and enhanced protein turnover. It is concluded that specific benefits associated with BCAA supplementation depend significantly on the type of liver disease and on the presence of inflammatory reaction. An important task for clinical research is to identify groups of patients for whom BCAA treatment can significantly improve the health-related quality of life and the prognosis of hepatic disease. PMID:20071143

  5. Regulation of Branched-Chain Amino Acid Biosynthesis in Salmonella typhimurium: Isolation of Regulatory Mutants

    PubMed Central

    Calvo, J. M.; Freundlich, M.; Umbarger, H. E.

    1969-01-01

    5′,5′,5′-Trifluoro-dl-leucine inhibited the activity of α-isopropylmalate synthetase (the initial enzyme unique to leucine biosynthesis) as well as the growth of Salmonella typhimurium. Mutants of S. typhimurium resistant to the analogue were isolated and characterized. In most cases, they overproduced and excreted leucine or leucine, valine, and isoleucine as a result of an alteration in the regulation of branched-chain amino acid biosynthesis. Biochemical and genetic tests allowed the mutants to be grouped into three classes: I, a moderately large group (13%) which had high, constitutive leucine biosynthetic enzyme levels and mutant sites linked to the leucine operon (operator constitutive); II, a single mutant in which the mutant site was linked to the leucine operon and in which α-isopropylmalate synthetase was not inhibited by leucine (feedback negative); III, a majority type which had constitutive levels of leucine, valine, and isoleucine biosynthetic enzymes and mutant sites unlinked to the leucine operon. Mutants of class I provide important evidence for the concept of an operon organization of genes involved in leucine biosynthesis. The properties of class III mutants indicate that there is some element involved in regulation which is common to the three pathways. Images PMID:4887507

  6. A safety assessment of branched chain saturated alcohols when used as fragrance ingredients.

    PubMed

    Belsito, D; Bickers, D; Bruze, M; Calow, P; Greim, H; Hanifin, J M; Rogers, A E; Saurat, J H; Sipes, I G; Tagami, H

    2010-07-01

    The Branched Chain Saturated Alcohol (BCSA) group of fragrance ingredients was evaluated for safety. In humans, no evidence of skin irritation was found at concentrations of 2-10%. Undiluted, 11 materials evaluated caused moderate to severe eye irritation. As current end product use levels are between 0.001% and 1.7%, eye irritation is not a concern. The materials have no or low sensitizing potential. For individuals who are already sensitized, an elicitation reaction is possible. Due to lack of UVA/UVB light-absorbing structures, and review of phototoxic/photoallergy data, the BCSA are not expected to elicit phototoxicity or photoallergy. The 15 materials tested have a low order of acute toxicity. Following repeated application, seven BCSA tested were of low systemic toxicity. Studies performed on eight BCSA and three metabolites show no in vivo or in vitro genotoxicity. A valid carcinogenicity study showed that 2-ethyl-1-hexanol is a weak inducer of liver tumors in female mice, however, the relevance of this effect and mode of action to humans is still a matter of debate. The Panel is of the opinion that there are no safety concerns regarding BCSA under the present levels of use and exposure.

  7. Attenuation of the protein wasting associated with bed rest by branched-chain amino acids

    NASA Technical Reports Server (NTRS)

    Stein, T. P.; Schluter, M. D.; Leskiw, M. J.; Boden, G.

    1999-01-01

    Bed rest is generally accepted as being an appropriate ground-based model for human spaceflight. The objectives of this study were to test the hypothesis that increasing the amount of branched-chain amino acids (BCAAs) in the diet could attenuate the protein loss associated with bed rest. Nineteen healthy subjects were randomized into two groups according to diet. During the 6 d of bed rest, the diets were supplemented with either 30 mmol/d each of three non-essential amino acids, glycine, serine, and alanine (control group), or with 30 mmol/d each of the BCAAs, leucine, isoleucine, and valine (BCAA group). Nutrition was supplied as a commercially available defined formula diet at a rate of 1.3 x REE. Nitrogen (N) balance and urinary 3-MeH excretion were determined for the 6 d. In our results, the urine-based estimate of N balance was 22.2 +/- 14.4 (n = 9) mg N.kg-1.d-1 and 60.5 +/- 10.1 mg (n = 8) N.kg-1.d-1 for the control and BCAA-supplemented groups, respectively (P < 0.05). Urinary 3-MeH excretion was unchanged in both groups with bed rest. We conclude that BCAA supplementation attenuates the N loss during short-term bed rest.

  8. Branched-chain amino acids and muscle ammonia detoxification in cirrhosis.

    PubMed

    Dam, Gitte; Ott, Peter; Aagaard, Niels Kristian; Vilstrup, Hendrik

    2013-06-01

    Branched-chain amino acids (BCAA) are used as a therapeutic nutritional supplement in patients with cirrhosis and hepatic encephalopathy (HE). During liver disease, the decreased capacity for urea synthesis and porto-systemic shunting reduce the hepatic clearance of ammonia and skeletal muscle may become the main alternative organ for ammonia detoxification. We here summarize current knowledge of muscle BCAA and ammonia metabolism with a focus on liver cirrhosis and HE. Plasma levels of BCAA are lower and muscle uptake of BCAA seems to be higher in patients with cirrhosis and hyperammonemia. BCAA metabolism may improve muscle net ammonia removal by supplying carbon skeletons for formation of alfa-ketoglutarate that combines with two ammonia molecules to become glutamine. An oral dose of BCAA enhances muscle ammonia metabolism but also transiently increases the arterial ammonia concentration, likely due to extramuscular metabolism of glutamine. We, therefore, speculate that the beneficial effect of long term intake of BCAA on HE demonstrated in clinical studies may be related to an improved muscle mass and nutritional status rather than to an ammonia lowering effect of BCAA themselves.

  9. Impairment of innate immune responses in cirrhotic patients and treatment by branched-chain amino acids.

    PubMed

    Nakamura, Ikuo

    2014-06-21

    It has been reported that host defense responses, such as phagocytic function of neutrophils and natural killer (NK) cell activity of lymphocytes, are impaired in cirrhotic patients. This review will concentrate on the impairment of innate immune responses in decompensated cirrhotic patients and the effect of the treatment by branched-chain amino acids (BCAA) on innate immune responses. We already reported that phagocytic function of neutrophils was significantly improved by 3-mo BCAA supplementation. In addition, the changes of NK activity were also significant at 3 mo of supplementation compared with before supplementation. Also, Fisher's ratios were reported to be significantly increased at 3 mo of BCAA supplementation compared with those before oral supplementation. Therefore, administration of BCAA could reduce the risk of bacterial and viral infection in patients with decompensated cirrhosis by restoring impaired innate immune responses of the host. In addition, it was also revealed that BCAA oral supplementation could reduce the risk of development of hepatocellular carcinoma in cirrhotic patients. The mechanisms of the effects will also be discussed in this review article.

  10. Sodium phenylbutyrate decreases plasma branched-chain amino acids in patients with urea cycle disorders.

    PubMed

    Burrage, Lindsay C; Jain, Mahim; Gandolfo, Laura; Lee, Brendan H; Nagamani, Sandesh C S

    2014-01-01

    Sodium phenylbutyrate (NaPBA) is a commonly used medication for the treatment of patients with urea cycle disorders (UCDs). Previous reports involving small numbers of patients with UCDs have shown that NaPBA treatment can result in lower plasma levels of the branched-chain amino acids (BCAA) but this has not been studied systematically. From a large cohort of patients (n=553) with UCDs enrolled in the Longitudinal Study of Urea Cycle Disorders, a collaborative multicenter study of the Urea Cycle Disorders Consortium, we evaluated whether treatment with NaPBA leads to a decrease in plasma BCAA levels. Our analysis shows that NaPBA use independently affects the plasma BCAA levels even after accounting for multiple confounding covariates. Moreover, NaPBA use increases the risk for BCAA deficiency. This effect of NaPBA seems specific to plasma BCAA levels, as levels of other essential amino acids are not altered by its use. Our study, in an unselected population of UCD subjects, is the largest to analyze the effects of NaPBA on BCAA metabolism and potentially has significant clinical implications. Our results indicate that plasma BCAA levels should to be monitored in patients treated with NaPBA since patients taking the medication are at increased risk for BCAA deficiency. On a broader scale, these findings could open avenues to explore NaPBA as a therapy in maple syrup urine disease and other common complex disorders with dysregulation of BCAA metabolism. PMID:25042691

  11. Metabolic engineering of Saccharomyces cerevisiae for the overproduction of short branched-chain fatty acids.

    PubMed

    Yu, Ai-Qun; Juwono, Nina Kurniasih Pratomo; Foo, Jee Loon; Leong, Susanna Su Jan; Chang, Matthew Wook

    2016-03-01

    Short branched-chain fatty acids (SBCFAs, C4-6) are versatile platform intermediates for the production of value-added products in the chemical industry. Currently, SBCFAs are mainly synthesized chemically, which can be costly and may cause environmental pollution. In order to develop an economical and environmentally friendly route for SBCFA production, we engineered Saccharomyces cerevisiae, a model eukaryotic microorganism of industrial significance, for the overproduction of SBCFAs. In particular, we employed a combinatorial metabolic engineering approach to optimize the native Ehrlich pathway in S. cerevisiae. First, chromosome-based combinatorial gene overexpression led to a 28.7-fold increase in the titer of SBCFAs. Second, deletion of key genes in competing pathways improved the production of SBCFAs to 387.4 mg/L, a 31.2-fold increase compared to the wild-type. Third, overexpression of the ATP-binding cassette (ABC) transporter PDR12 increased the secretion of SBCFAs. Taken together, we demonstrated that the combinatorial metabolic engineering approach used in this study effectively improved SBCFA biosynthesis in S. cerevisiae through the incorporation of a chromosome-based combinatorial gene overexpression strategy, elimination of genes in competitive pathways and overexpression of a native transporter. We envision that this strategy could also be applied to the production of other chemicals in S. cerevisiae and may be extended to other microbes for strain improvement.

  12. A branched-chain amino acid metabolite drives vascular fatty acid transport and causes insulin resistance.

    PubMed

    Jang, Cholsoon; Oh, Sungwhan F; Wada, Shogo; Rowe, Glenn C; Liu, Laura; Chan, Mun Chun; Rhee, James; Hoshino, Atsushi; Kim, Boa; Ibrahim, Ayon; Baca, Luisa G; Kim, Esl; Ghosh, Chandra C; Parikh, Samir M; Jiang, Aihua; Chu, Qingwei; Forman, Daniel E; Lecker, Stewart H; Krishnaiah, Saikumari; Rabinowitz, Joshua D; Weljie, Aalim M; Baur, Joseph A; Kasper, Dennis L; Arany, Zoltan

    2016-04-01

    Epidemiological and experimental data implicate branched-chain amino acids (BCAAs) in the development of insulin resistance, but the mechanisms that underlie this link remain unclear. Insulin resistance in skeletal muscle stems from the excess accumulation of lipid species, a process that requires blood-borne lipids to initially traverse the blood vessel wall. How this trans-endothelial transport occurs and how it is regulated are not well understood. Here we leveraged PPARGC1a (also known as PGC-1α; encoded by Ppargc1a), a transcriptional coactivator that regulates broad programs of fatty acid consumption, to identify 3-hydroxyisobutyrate (3-HIB), a catabolic intermediate of the BCAA valine, as a new paracrine regulator of trans-endothelial fatty acid transport. We found that 3-HIB is secreted from muscle cells, activates endothelial fatty acid transport, stimulates muscle fatty acid uptake in vivo and promotes lipid accumulation in muscle, leading to insulin resistance in mice. Conversely, inhibiting the synthesis of 3-HIB in muscle cells blocks the ability of PGC-1α to promote endothelial fatty acid uptake. 3-HIB levels are elevated in muscle from db/db mice with diabetes and from human subjects with diabetes, as compared to those without diabetes. These data unveil a mechanism in which the metabolite 3-HIB, by regulating the trans-endothelial flux of fatty acids, links the regulation of fatty acid flux to BCAA catabolism, providing a mechanistic explanation for how increased BCAA catabolic flux can cause diabetes. PMID:26950361

  13. The Emerging Role of Branched-Chain Amino Acids in Insulin Resistance and Metabolism

    PubMed Central

    Yoon, Mee-Sup

    2016-01-01

    Insulin is required for maintenance of glucose homeostasis. Despite the importance of insulin sensitivity to metabolic health, the mechanisms that induce insulin resistance remain unclear. Branched-chain amino acids (BCAAs) belong to the essential amino acids, which are both direct and indirect nutrient signals. Even though BCAAs have been reported to improve metabolic health, an increased BCAA plasma level is associated with a high risk of metabolic disorder and future insulin resistance, or type 2 diabetes mellitus (T2DM). The activation of mammalian target of rapamycin complex 1 (mTORC1) by BCAAs has been suggested to cause insulin resistance. In addition, defective BCAA oxidative metabolism might occur in obesity, leading to a further accumulation of BCAAs and toxic intermediates. This review provides the current understanding of the mechanism of BCAA-induced mTORC1 activation, as well as the effect of mTOR activation on metabolic health in terms of insulin sensitivity. Furthermore, the effects of impaired BCAA metabolism will be discussed in detail. PMID:27376324

  14. Importance of Branched-Chain Amino Acid Utilization in Francisella Intracellular Adaptation

    PubMed Central

    Gesbert, Gael; Ramond, Elodie; Tros, Fabiola; Dairou, Julien; Frapy, Eric; Barel, Monique

    2014-01-01

    Intracellular bacterial pathogens have adapted their metabolism to optimally utilize the nutrients available in infected host cells. We recently reported the identification of an asparagine transporter required specifically for cytosolic multiplication of Francisella. In the present work, we characterized a new member of the major super family (MSF) of transporters, involved in isoleucine uptake. We show that this transporter (here designated IleP) plays a critical role in intracellular metabolic adaptation of Francisella. Inactivation of IleP severely impaired intracellular F. tularensis subsp. novicida multiplication in all cell types tested and reduced bacterial virulence in the mouse model. To further establish the importance of the ileP gene in F. tularensis pathogenesis, we constructed a chromosomal deletion mutant of ileP (ΔFTL_1803) in the F. tularensis subsp. holarctica live vaccine strain (LVS). Inactivation of IleP in the F. tularensis LVS provoked comparable intracellular growth defects, confirming the critical role of this transporter in isoleucine uptake. The data presented establish, for the first time, the importance of isoleucine utilization for efficient phagosomal escape and cytosolic multiplication of Francisella and suggest that virulent F. tularensis subspecies have lost their branched-chain amino acid biosynthetic pathways and rely exclusively on dedicated uptake systems. This loss of function is likely to reflect an evolution toward a predominantly intracellular life style of the pathogen. Amino acid transporters should be thus considered major players in the adaptation of intracellular pathogens. PMID:25332124

  15. Branched chain amino acid metabolism profiles in progressive human nonalcoholic fatty liver disease.

    PubMed

    Lake, April D; Novak, Petr; Shipkova, Petia; Aranibar, Nelly; Robertson, Donald G; Reily, Michael D; Lehman-McKeeman, Lois D; Vaillancourt, Richard R; Cherrington, Nathan J

    2015-03-01

    Nonalcoholic fatty liver disease (NAFLD) is a globally widespread disease of increasing clinical significance. The pathological progression of the disease from simple steatosis to nonalcoholic steatohepatitis (NASH) has been well defined, however, the contribution of altered branched chain amino acid metabolomic profiles to the progression of NAFLD is not known. The three BCAAs: leucine, isoleucine and valine are known to mediate activation of several important hepatic metabolic signaling pathways ranging from insulin signaling to glucose regulation. The purpose of this study is to profile changes in hepatic BCAA metabolite levels with transcriptomic changes in the progression of human NAFLD to discover novel mechanisms of disease progression. Metabolomic and transcriptomic data sets representing the spectrum of human NAFLD (normal, steatosis, NASH fatty, and NASH not fatty livers) were utilized for this study. During the transition from steatosis to NASH, increases in the levels of leucine (127% of normal), isoleucine (139%), and valine (147%) were observed. Carnitine metabolites also exhibited significantly elevated profiles in NASH fatty and NASH not fatty samples and included propionyl, hexanoyl, lauryl, acetyl and butyryl carnitine. Amino acid and BCAA metabolism gene sets were significantly enriched among downregulated genes during NASH. These cumulative alterations in BCAA metabolite and amino acid metabolism gene profiles represent adaptive physiological responses to disease-induced hepatic stress in NASH patients.

  16. The Emerging Role of Branched-Chain Amino Acids in Insulin Resistance and Metabolism.

    PubMed

    Yoon, Mee-Sup

    2016-01-01

    Insulin is required for maintenance of glucose homeostasis. Despite the importance of insulin sensitivity to metabolic health, the mechanisms that induce insulin resistance remain unclear. Branched-chain amino acids (BCAAs) belong to the essential amino acids, which are both direct and indirect nutrient signals. Even though BCAAs have been reported to improve metabolic health, an increased BCAA plasma level is associated with a high risk of metabolic disorder and future insulin resistance, or type 2 diabetes mellitus (T2DM). The activation of mammalian target of rapamycin complex 1 (mTORC1) by BCAAs has been suggested to cause insulin resistance. In addition, defective BCAA oxidative metabolism might occur in obesity, leading to a further accumulation of BCAAs and toxic intermediates. This review provides the current understanding of the mechanism of BCAA-induced mTORC1 activation, as well as the effect of mTOR activation on metabolic health in terms of insulin sensitivity. Furthermore, the effects of impaired BCAA metabolism will be discussed in detail. PMID:27376324

  17. Impact of dietary branched chain amino acids concentration on broiler chicks during aflatoxicosis.

    PubMed

    Chen, X; Zhang, Q; Applegate, T J

    2016-06-01

    A 20-day trial was conducted to determine the effects of dietary branched-chain amino acids (BCAA) on performance, nutrient digestibility, and gene expression of the mTOR pathway in broiler chicks when exposed to aflatoxin B1 (AFB1). The 6 dietary treatments were arranged in a 2 × 3 factorial with 3 BCAA concentrations (1.16, 1.94, and 2.73%) with or without 1.5 mg/kg AFB1 (1.77 mg/kg analyzed). Each diet was fed to 8 replicate cages (6 chicks per cage) from 6 to 20 d of age. Exposure to AFB1 significantly reduced gain:feed ratio and breast muscle weight (P < 0.05), and tended to decrease cumulative BW gain (P = 0.087), while increasing dietary BCAA improved all performance measures (P ≤ 0.0002), except relative breast muscle weight. Apparent ileal digestibility of N and 9 amino acids were increased by AFB1 (P ≤ 0.05), but were reduced by higher dietary BCAA (P ≤ 0.023). Jejunum histology was not affected by AFB1, while higher dietary BCAA tended to increase villus height (P = 0.08). Additionally, the gene expression of mTOR pathway (mTOR, 4EBP1, and S6K1) from liver and jejunum were not affected by dietary treatments, while muscle expression of S6K1 tended to be increased by AFB1 (P = 0.07). No significant interaction between AFB1 and dietary BCAA were observed for any measures in the current study. Results from this study suggested that feed AFB1 contamination can significantly reduce growth performance and breast muscle growth in broiler chicks at 20 d. Higher BCAA supply may have beneficial impact on bird performance, but this effect is independent of AFB1 exposure. PMID:26957625

  18. L-citrulline-malate influence over branched chain amino acid utilization during exercise.

    PubMed

    Sureda, Antoni; Córdova, Alfredo; Ferrer, Miguel D; Pérez, Gerardo; Tur, Josep A; Pons, Antoni

    2010-09-01

    Exhaustive exercise induces disturbances in metabolic homeostasis which can result in amino acid catabolism and limited L-arginine availability. Oral L-citrulline supplementation raises plasma L-arginine concentration and augments NO-dependent signalling. Our aim was to evaluate the effects of diet supplementation with L-citrulline-malate prior to intense exercise on the metabolic handle of plasma amino acids and on the products of metabolism of arginine as creatinine, urea and nitrite and the possible effects on the hormonal levels. Seventeen voluntary male pre-professional cyclists were randomly assigned to one of two groups: control or supplemented (6 g L-citrulline-malate 2 h prior exercise) and participated in a 137-km cycling stage. Blood samples were taken in basal conditions, 15 min after the race and 3 h post race (recovery). Most essential amino acids significantly decreased their plasma concentration as a result of exercise; however, most non-essential amino acids tended to significantly increase their concentration. Citrulline-malate ingestion significantly increased the plasma concentration of citrulline, arginine, ornithine, urea, creatinine and nitrite (p < 0.05) and significantly decreased the isoleucine concentration from basal measures to after exercise (p < 0.05). Insulin levels significantly increased after exercise in both groups (p < 0.05) returning to basal values at recovery. Growth hormone increased after exercise in both groups, although the increase was higher in the citrulline-malate supplemented group (p < 0.05). L-citrulline-malate supplementation can enhance the use of amino acids, especially the branched chain amino acids during exercise and also enhance the production of arginine-derived metabolites such as nitrite, creatinine, ornithine and urea. PMID:20499249

  19. Plasma branched-chain amino acids and incident cardiovascular disease in the PREDIMED trial

    PubMed Central

    Ruiz-Canela, Miguel; Toledo, Estefania; Clish, Clary B.; Hruby, Adela; Liang, Liming; Salas-Salvadó, Jordi; Razquin, Cristina; Corella, Dolores; Estruch, Ramón; Ros, Emilio; Fitó, Montserrat; Gómez-Gracia, Enrique; Arós, Fernando; Fiol, Miquel; Lapetra, José; Serra-Majem, Lluis; Martínez-González, Miguel A.; Hu, Frank B.

    2016-01-01

    Background The role of branched-chain amino acids (BCAAs) in cardiovascular disease (CVD) remains poorly understood. We hypothesized that baseline BCAA concentrations predict future risk of CVD and that a Mediterranean Diet (MedDiet) intervention may counteract this effect. Methods We developed a case-cohort study within the “PREvención con DIeta MEDiterránea” (PREDIMED), with 226 incident CVD cases and 781 non-cases. We used LC-MS/MS to measure plasma BCAAs (leucine, isoleucine and valine), both at baseline and after 1-year follow-up. The primary outcome was a composite of incident stroke, myocardial infarction, or cardiovascular death. Results After adjustment for potential confounders, baseline leucine and isoleucine concentrations were associated with higher CVD risk: the hazard ratios (HRs) for the highest vs. lowest quartile were 1.70 (95% confidence interval, 1.05–2.76) and 2.09 (1.27–3.44), respectively. Stronger associations were found for stroke. For both CVD and stroke, we found higher HRs across successive quartiles of BCAAs in the control group than in the MedDiet groups. Using stroke as the outcome, a significant interaction (P=0.009) between the baseline BCAA score and the intervention with MedDiet was observed. No significant effect of the intervention on 1-yr changes in BCAAs nor any association between 1-year changes in BCAAs and CVD were observed. Conclusions Higher concentrations of baseline BCAAs were associated with increased risk of CVD, especially stroke, in a high cardiovascular risk population. A Mediterranean-style diet had a negligible effect on 1-year changes in BCAAs, but it may counteract the harmful effects of BCAAs on stroke. PMID:26888892

  20. Application of branched-chain amino acids in human pathological states: renal failure.

    PubMed

    Cano, Noël J M; Fouque, Denis; Leverve, Xavier M

    2006-01-01

    During renal failure, abnormalities of BCAA and branched-chain keto acid (BCKA) metabolism are due to both the lack of renal contribution to amino acid metabolism and the impact of renal failure and acidosis on whole-body nitrogen metabolism. Abnormal BCAA and BCKA metabolism result in BCAA depletion as reflected by low plasma BCAAs and cellular valine. BCAA metabolic disturbances can alter tissue activities, particularly brain function, and nutritional status. In dialysis patients, BCAA oral supplementation can induce an improvement of appetite and nutritional status. During chronic renal failure, the aims of nutritional interventions are to minimize uremic toxicity, avoid malnutrition and delay progression of kidney disease. BCAA and BCKA supplements have been proposed to decrease further protein intake while maintaining satisfactory nutritional status. In this setting, BCAAs or BCKAs have not been administrated solely but in association with other essential AA or keto analogs. Therefore, the proper effects of BCAAs and/or BCKAs have not been studied separately. Protein restriction together with keto acids and/or essential AAs has been reported to improve insulin sensitivity and hyperparathyroidism and to be compatible with a preservation of nutritional status. Nonetheless, a careful monitoring of protein-calorie intake and nutritional status is needed. A recent meta-analysis concluded that reducing protein intake in patients with chronic renal failure reduces the occurrence of renal death by approximately 40% as compared with larger or unrestricted protein intake. The additional effect of essential amino acids and keto acids on retardation of progression of renal failure has not been demonstrated.

  1. Branched-chain amino acid supplementation during bed rest: effect on recovery

    NASA Technical Reports Server (NTRS)

    Stein, T. P.; Donaldson, M. R.; Leskiw, M. J.; Schluter, M. D.; Baggett, D. W.; Boden, G.

    2003-01-01

    Bed rest is associated with a loss of protein from the weight-bearing muscle. The objectives of this study are to determine whether increasing dietary branched-chain amino acids (BCAAs) during bed rest improves the anabolic response after bed rest. The study consisted of a 1-day ambulatory period, 14 days of bed rest, and a 4-day recovery period. During bed rest, dietary intake was supplemented with either 30 mmol/day each of glycine, serine, and alanine (group 1) or with 30 mmol/day each of the three BCAAs (group 2). Whole body protein synthesis was determined with U-(15)N-labeled amino acids, muscle, and selected plasma protein synthesis with l-[(2)H(5)]phenylalanine. Total glucose production and gluconeogenesis from alanine were determined with l-[U-(13)C(3)]alanine and [6,6-(2)H(2)]glucose. During bed rest, nitrogen (N) retention was greater with BCAA feeding (56 +/- 6 vs. 26 +/- 12 mg N. kg(-1). day(-1), P < 0.05). There was no effect of BCAA supplementation on either whole body, muscle, or plasma protein synthesis or the rate of 3-MeH excretion. Muscle tissue free amino acid concentrations were increased during bed rest with BCAA (0.214 +/- 0.066 vs. 0.088 +/- 0.12 nmol/mg protein, P < 0.05). Total glucose production and gluconeogenesis from alanine were unchanged with bed rest but were significantly reduced (P < 0.05) with the BCAA group in the recovery phase. In conclusion, the improved N retention during bed rest is due, at least in part, to accretion of amino acids in the tissue free amino acid pools. The amount accreted is not enough to impact protein kinetics in the recovery phase but does improve N retention by providing additional essential amino acids in the early recovery phase.

  2. Glucocorticoid regulation of branched-chain alpha-ketoacid dehydrogenase E2 subunit gene expression.

    PubMed Central

    Costeas, P A; Chinsky, J M

    2000-01-01

    Regulation of the mammalian branched-chain alpha-ketoacid dehydrogenase complex (BCKAD) occurs under a variety of stressful conditions associated with changes in circulating glucocorticoids. Multiple levels of regulation in hepatocytes, including alteration of the levels of the structural subunits available for assembly (E1, alpha-ketoacid decarboxylase; E2, dihydrolipoamide acyltransferase; and E3, dihydrolipoamide dehydrogenase), as well as BCKAD kinase, which serves to phosphorylate the E1alpha subunit and inactivate complex activity, have been proposed. The direct role of glucocorticoids in regulating the expression of the murine gene encoding the major BCKAD subunit E2, upon which the other BCKAD subunits assemble, was therefore examined. Deletion analysis of the 5' proximal 7.0 kb of the murine E2 promoter sequence, using E2 promoter/luciferase expression minigene plasmids introduced into the hepatic H4IIEC3 cell line, suggested a promoter proximal region responsive to glucocorticoid regulation. Linker-scanning mutagenesis combined with deletion analysis established this functional glucocorticoid-responsive unit (GRU) to be located near the murine E2 proximal promoter site at -140 to -70 bp upstream from the transcription initiation site. The presence of this region in plasmid minigenes, containing varying amounts of the murine genomic sequence 5' upstream from proximal E2 promoter sequences, conferred 2-10 fold increases in luciferase reporter gene expression in H4IIEC3 cells, whether introduced by transient transfection or following co-selection for stable transfectants. The GRU region itself appeared to contain multiple interacting elements that combine to regulate overall E2 promoter activity in response to changing physiological conditions associated with varying concentrations of glucocorticoids and likely other hormonal effectors. PMID:10749674

  3. Inhibitory effect of aroma on the bitterness of branched-chain amino acid solutions.

    PubMed

    Mukai, Junji; Tokuyama, Emi; Ishizaka, Toshihiko; Okada, Sachie; Uchida, Takahiro

    2007-11-01

    Nutritional products for patients with liver failure available on the Japanese market contain many branched-chain amino acids (BCAAs) such as L-leucine, L-isoleucine, and L-valine, which not only have a bitter taste but also strong, unpleasant odours, leading to low palatability. The palatability of these nutritional products can be significantly improved by the addition of flavoured powders containing various kinds of tastants (sucrose, citric acid, etc.) and odourants (fruit, coffee aromas, etc.). The specific effects of the aroma of flavoured powders have not yet been clearly evaluated. In the present article, the inhibitory effect of aroma on the bitterness of BCAA solutions was examined. The bitterness intensity of a BCAA solution at the same concentration as Aminoleban EN was defined as 3.5 (measured by a previously described gustatory sensation method). The bitterness threshold of a BCAA standard solution without added aroma was estimated to be 1.87, while those of BCAA solutions containing green-tea, coffee, apple, vanilla, or strawberry aromas were 2.02, 1.98, 2.35, 2.40 and 2.87, respectively, when evaluated by the probit method. This shows that the addition of an aroma can elevate the bitterness threshold in human volunteers. The green-tea and coffee aromas predominantly evoked bitterness, while the vanilla aroma predominantly evoked sweetness. Apple and strawberry aromas evoked both sweetness and sourness, with the apple aroma having stronger sourness and the strawberry aroma stronger sweetness. Thus, a 'sweet' aroma suppresses the bitterness of BCAA, with coexisting sourness also participating in the bitterness inhibition.

  4. Comparative Genomics of Regulation of Fatty Acid and Branched-chain Amino Acid Utilization in Proteobacteria

    SciTech Connect

    Kazakov, Alexey E.; Rodionov, Dmitry A.; Arkin, Adam Paul; Dubchak, Inna; Gelfand, Mikhail S.; Alm, Eric

    2008-10-31

    Bacteria can use branched-chain amino acids (ILV, i.e. isoleucine, leucine, valine) and fatty acids (FA) as sole carbon and energy sources convering ILV into acetyl-CoA, propanoyl-CoA and propionyl-CoA, respectively. In this work, we used the comparative genomic approach to identify candidate transcriptional factors and DNA motifs that control ILV and FA utilization pathways in proteobacteria. The metabolic regulons were characterized based on the identification and comparison of candidate transcription factor binding sites in groups of phylogenetically related genomes. The reconstructed ILV/FA regulatory network demonstrates considerable variability and involves six transcriptional factors from the MerR, TetR and GntR families binding to eleven distinct DNA motifs. The ILV degradation genes in gamma- and beta-proteobacteria are mainly regulated by anovel regulator from the MerR family (e.g., LiuR in Pseudomonas aeruginosa) (40 species), in addition, the TetR-type regulator LiuQ was identified in some beta-proteobacteria (8 species). Besides the core set of ILV utilization genes, the LiuR regulon in some lineages is expanded to include genes from other metabolic pathways, such as the glyoxylate shunt and glutamate synthase in the Shewanella species. The FA degradation genes are controlled by four regulators including FadR in gamma-proteobacteria (34 species), PsrA in gamma- and beta-proteobacteria (45 species), FadP in beta-proteobacteria (14 species), and LiuR orthologs in alpha-proteobacteria (22 species). The remarkable variability of the regulatory systems associated with the FA degradation pathway is discussed from the functional and evolutionary points of view.

  5. Spontaneous formation of bilayers and vesicles in mixtures of single-chain alkyl carboxylates: effect of pH and aging and cytotoxicity studies.

    PubMed

    Vlachy, N; Merle, C; Touraud, D; Schmidt, J; Talmon, Y; Heilmann, J; Kunz, W

    2008-09-16

    We report the observation of bilayer fragments, some of which close to form vesicles, over a large range of pH at room temperature from mixtures of single-chain biocompatible commercially available nontoxic alkyl carboxylic surfactants after neutralization with HCl. The pH at which the morphological transitions occur is varied only by changing the ratio between two surfactants: the alkyloligoethyleneoxide carboxylate and sodium laurate. The effect of aging of the mixed surfactant systems in the pH region desired for dermatologic application (4.5 < pH < 7) is also studied. Finally, we show results of cytotoxicity studies on the surfactant mixtures.

  6. Regulation of indole-3-acetic acid biosynthesis by branched-chain amino acids in Enterobacter cloacae UW5.

    PubMed

    Parsons, Cassandra V; Harris, Danielle M M; Patten, Cheryl L

    2015-09-01

    The soil bacterium Enterobacter cloacae UW5 produces the rhizosphere signaling molecule indole-3-acetic acid (IAA) via the indolepyruvate pathway. Expression of indolepyruvate decarboxylase, a key pathway enzyme encoded by ipdC, is upregulated by the transcription factor TyrR in response to aromatic amino acids. Some members of the TyrR regulon may also be controlled by branched-chain amino acids and here we show that expression from the ipdC promoter and production of IAA are downregulated by valine, leucine and isoleucine. Regulation of the IAA synthesis pathway by both aromatic and branched-chain amino acids suggests a broader role for this pathway in bacterial physiology, beyond plant interactions.

  7. Purification, crystallization and preliminary X-ray crystallographic analysis of branched-chain aminotransferase from Deinococcus radiodurans

    SciTech Connect

    Chen, Chung-Der; Huang, Tien-Feng; Lin, Chih-Hao; Guan, Hong-Hsiang; Hsieh, Yin-Cheng; Lin, Yi-Hung; Huang, Yen-Chieh; Liu, Ming-Yih; Chang, Wen-Chang; Chen, Chun-Jung

    2007-06-01

    The crystallization of branched-chain aminotransferase from D. radiodurans is described. The branched-chain amino-acid aminotransferase (BCAT), which requires pyridoxal 5′-phosphate (PLP) as a cofactor, is a key enzyme in the biosynthetic pathway of the hydrophobic amino acids leucine, isoleucine and valine. DrBCAT from Deinococcus radiodurans, which has a molecular weight of 40.9 kDa, was crystallized using the hanging-drop vapour-diffusion method. According to X-ray diffraction data to 2.50 Å resolution from a DrBCAT crystal, the crystal belongs to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 56.37, b = 90.70, c = 155.47 Å. Preliminary analysis indicates the presence of two DrBCAT molecules in the asymmetric unit, with a solvent content of 47.52%.

  8. Structural characterization of saturated branched chain fatty acid methyl esters by collisional dissociation of molecular ions generated by electron ionization.

    PubMed

    Ran-Ressler, Rinat R; Lawrence, Peter; Brenna, J Thomas

    2012-01-01

    Saturated branched chain fatty acids (BCFA) are present as complex mixtures in numerous biological samples. The traditional method for structure elucidation, electron ionization (EI) mass spectrometry, sometimes does not unambiguously enable assignment of branching in isomeric BCFA. Zirrolli and Murphy (Zirrolli , J. A. , and R. A. Murphy. 1993. Low-energy tandem mass spectrometry of the molecular ion derived from fatty acid methyl esters: a novel method for analysis of branched-chain fatty acids. J. Am. Soc. Mass Spectrom. 4: 223-229.) showed that the molecular ions of four BCFA methyl ester (BCFAME) yield highly characteristic fragments upon collisional dissociation using a triple quadrupole instrument. Here, we confirm and extend these results by analysis using a tabletop 3-D ion trap for activated molecular ion EI-MS/MS to 30 BCFAME. iso-BCFAME produces a prominent ion (30-100% of base peak) for [M-43] (M-C₃H₇), corresponding to the terminal isopropyl moiety in the original iso-BCFAME. Anteiso-FAME yield prominent ions (20-100% of base peak) corresponding to losses on both side of the methyl branch, [M-29] and [M-57], and tend to produce more prominent m/z 115 peaks corresponding to a cyclization product around the ester. Dimethyl and tetramethyl FAME, with branches separated by at least one methylene group, yield fragment on both sides of the sites of methyl branches that are more than 6 C away from the carboxyl carbon. EI-MS/MS yields uniquely specific ions that enable highly confident structural identification and quantification of BCFAME.

  9. Effect of lipid supplementation on milk odd- and branched-chain fatty acids in dairy cows.

    PubMed

    Baumann, E; Chouinard, P Y; Lebeuf, Y; Rico, D E; Gervais, R

    2016-08-01

    Eight ruminally fistulated, multiparous Holstein cows were arranged in a double 4×4 Latin square with 14-d periods to investigate the effects of lipid supplementation on performance, rumen parameters, the milk odd- and branched-chain fatty acid (OBCFA) profile, and the relationships between milk OBCFA and rumen parameters. Lipid supplementation is known to inhibit microbial growth in the rumen, decrease de novo microbial fatty acid synthesis, and increase the uptake of circulating fatty acids by the mammary gland; treatments were selected to isolate these effects on the milk OBCFA profile. The 4 treatments were (1) a lipid-free emulsion medium infused in the rumen (CTL), (2) soybean oil as a source of polyunsaturated fatty acids infused in the rumen (RSO), (3) saturated fatty acids (38% 16:0, 40% 18:0) infused in the rumen (RSF), and (4) saturated fatty acids infused in the abomasum (ASF). Fat supplements were provided continuously as emulsions at a rate of 450g/d. Preplanned contrasts compared CTL to RSO, RSO to RSF, and RSF to ASF. Infusing RSO slightly decreased ruminal pH, but did not affect volatile fatty acids profile and milk fat concentration as compared with CTL. The yields of energy-corrected milk, fat, and protein were greater with RSF compared with RSO. The concentration of odd-chain fatty acids was decreased by RSO, whereas even-chain iso fatty acids were not affected. Milk fat concentration of 17:0 + cis-9 17:1 was higher for RSF than for RSO, due to the saturated fatty acids supplement containing 2% 17:0 + cis-9 17:1. Limited differences were observed in the milk OBCFA profile between RSF and ASF. A multiple regression analysis yielded the following equation for predicting rumen pH based on milk fatty acids: pH=6.24 - (0.56×4:0) + (1.67 × iso 14:0) + (4.22 × iso 15:0) + (9.41×22:0). Rumen propionate concentration was negatively correlated with milk fat concentration of iso 14:0 and positively correlated with milk 15:0, whereas the acetate

  10. Hypervalinemia and hyperleucine-isoleucinemia caused by mutations in the branched-chain-amino-acid aminotransferase gene.

    PubMed

    Wang, X L; Li, C J; Xing, Y; Yang, Y H; Jia, J P

    2015-09-01

    Valine, leucine, and isoleucine are essential branched chain amino acids (BCAAs). When BCAA metabolism is genetically impaired in human, serum levels of BCAA and/or their metabolites rise considerably, causing severe neurological dysfunction. The first step in BCAA catabolism is catalyzed by branched chain aminotransferase (BCAT). Hypervalinemia and hyperleucine-isoleucinemia caused by BCAT gene mutation in human have not been reported previously. A 25-year-old man presented with headache complaints and mild memory impairment for about six years. Brain MRI showed symmetric white matter abnormal signals. Metabolic studies revealed remarkably elevated plasma valine and leucine concentrations. Maple syrup urine disease (MSUD) diagnosis was not supported since all genes for the branched-chain α-keto acid dehydrogenase complex (BCKD) gene were normal. Interestingly, two heterogeneous BCAT2 gene mutations were found in the patient, including c.509G > A (p.Arg170Gln) and c.790G > A (p.Glu264Lys). In addition, c.509G > A (p.Arg170Gln) and c.790G > A (p.Glu264Lys) were found in his father and mother, respectively, suggesting an autosomal recessive disorder. BCAT2 functional studies demonstrated that the two BCAT2 gene mutations resulted in decreased BCAT2 enzyme activity. After treatment with vitamin B6, the levels of BCAA, especially valine were remarkably decreased and brain MRI lesions were improved. These findings suggest a new type of branched chain amino acid metabolism disorder. This rare case provides great insight into the further understanding of BCAA metabolism and its defect in human. BCAT2 gene mutations can cause hypervalinemia and hyperleucine-isoleucinemia, which are associated with brain white matter lesions. PMID:25653144

  11. Characterization of the Branched-Chain Amino Acid Aminotransferase Enzyme Family in Tomato1[W][OA

    PubMed Central

    Maloney, Gregory S.; Kochevenko, Andrej; Tieman, Denise M.; Tohge, Takayuki; Krieger, Uri; Zamir, Dani; Taylor, Mark G.; Fernie, Alisdair R.; Klee, Harry J.

    2010-01-01

    Branched-chain amino acids (BCAAs) are synthesized in plants from branched-chain keto acids, but their metabolism is not completely understood. The interface of BCAA metabolism lies with branched-chain aminotransferases (BCAT) that catalyze both the last anabolic step and the first catabolic step. In this study, six BCAT genes from the cultivated tomato (Solanum lycopersicum) were identified and characterized. SlBCAT1, -2, -3, and -4 are expressed in multiple plant tissues, while SlBCAT5 and -6 were undetectable. SlBCAT1 and -2 are located in the mitochondria, SlBCAT3 and -4 are located in chloroplasts, while SlBCAT5 and -6 are located in the cytosol and vacuole, respectively. SlBCAT1, -2, -3, and -4 were able to restore growth of Escherichia coli BCAA auxotrophic cells, but SlBCAT1 and -2 were less effective than SlBCAT3 and -4 in growth restoration. All enzymes were active in the forward (BCAA synthesis) and reverse (branched-chain keto acid synthesis) reactions. SlBCAT3 and -4 exhibited a preference for the forward reaction, while SlBCAT1 and -2 were more active in the reverse reaction. While overexpression of SlBCAT1 or -3 in tomato fruit did not significantly alter amino acid levels, an expression quantitative trait locus on chromosome 3, associated with substantially higher expression of Solanum pennellii BCAT4, did significantly increase BCAA levels. Conversely, antisense-mediated reduction of SlBCAT1 resulted in higher levels of BCAAs. Together, these results support a model in which the mitochondrial SlBCAT1 and -2 function in BCAA catabolism while the chloroplastic SlBCAT3 and -4 function in BCAA synthesis. PMID:20435740

  12. Hypervalinemia and hyperleucine-isoleucinemia caused by mutations in the branched-chain-amino-acid aminotransferase gene.

    PubMed

    Wang, X L; Li, C J; Xing, Y; Yang, Y H; Jia, J P

    2015-09-01

    Valine, leucine, and isoleucine are essential branched chain amino acids (BCAAs). When BCAA metabolism is genetically impaired in human, serum levels of BCAA and/or their metabolites rise considerably, causing severe neurological dysfunction. The first step in BCAA catabolism is catalyzed by branched chain aminotransferase (BCAT). Hypervalinemia and hyperleucine-isoleucinemia caused by BCAT gene mutation in human have not been reported previously. A 25-year-old man presented with headache complaints and mild memory impairment for about six years. Brain MRI showed symmetric white matter abnormal signals. Metabolic studies revealed remarkably elevated plasma valine and leucine concentrations. Maple syrup urine disease (MSUD) diagnosis was not supported since all genes for the branched-chain α-keto acid dehydrogenase complex (BCKD) gene were normal. Interestingly, two heterogeneous BCAT2 gene mutations were found in the patient, including c.509G > A (p.Arg170Gln) and c.790G > A (p.Glu264Lys). In addition, c.509G > A (p.Arg170Gln) and c.790G > A (p.Glu264Lys) were found in his father and mother, respectively, suggesting an autosomal recessive disorder. BCAT2 functional studies demonstrated that the two BCAT2 gene mutations resulted in decreased BCAT2 enzyme activity. After treatment with vitamin B6, the levels of BCAA, especially valine were remarkably decreased and brain MRI lesions were improved. These findings suggest a new type of branched chain amino acid metabolism disorder. This rare case provides great insight into the further understanding of BCAA metabolism and its defect in human. BCAT2 gene mutations can cause hypervalinemia and hyperleucine-isoleucinemia, which are associated with brain white matter lesions.

  13. Electrical conductivity and glass formation in nitrile-functionalized pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids: chain length and odd-even effects of the alkyl spacer between the pyrrolidinium ring and the nitrile group.

    PubMed

    Leys, Jan; Tripathi, Chandra Shekhar Pati; Glorieux, Christ; Zahn, Stefan; Kirchner, Barbara; Longuemart, Stéphane; Lethesh, Kallidanthiyil Chellappan; Nockemann, Peter; Dehaen, Wim; Binnemans, Koen

    2014-06-14

    The electrical conductivity of a series of pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids, functionalized with a nitrile (cyano) group at the end of an alkyl chain attached to the cation, was studied in the temperature range between 173 K and 393 K. The glass formation of the ionic liquids is influenced by the length of the alkyl spacer separating the nitrile function from the pyrrolidinium ring. The electrical conductivity and the viscosity do not show a monotonic dependence on the alkyl spacer length, but rather an odd-even effect. An explanation for this behavior is given, including the potential energy landscape picture for the glass transition.

  14. The role of cellular structure on increasing the detonability limits of three-step chain-branching detonations

    SciTech Connect

    Short, Mark; Kiyanda, Charles B; Quirk, James J; Sharpe, Gary J

    2011-01-27

    In [1], the dynamics of a pulsating three-step chain-branching detonation were studied. The reaction model consists of, sequentially, chain-initiation, chain-branching and chain-termination steps. The chain-initiation and chain-branching steps are taken to be thermally neutral, with chemical energy release occuring in the chain-termination stage. The purpose of the present study is to examine whether cellular detonation structure can increase the value of the chain-branching cross-over temperature T{sub b} at which fully coupled detonation solutions are observed over those in 1 D. The basic concept is straightforward and has been discussed in [1] and [3]; if T{sub s} drops below T{sub b} at the lead shock, the passage of a transverse shock can increase both the lead shock temperature and the temperature behind the transverse wave back above T{sub b}, thus sustaining an unstable cellular detonation for values of T{sub b} for which a one-dimensional pulsating detonation will fail. Experiments potentially supporting this hypothesis with irregular detonations have been shown in [3] in a shock tube with acoustically absorbing walls. Removal of the transverse waves results in detonation failure, giving way to a decoupled shock-flame complex. A number of questions remain to be addressed regarding the possibility of such a mechanism, and, if so, about the precise mechanisms driving the cellular structure for large T{sub b}. For instance, one might ask what sets the cell size in a chain-branching detonation, particularly could the characteristic cell size be set by the chain-branching cross-over temperature T{sub b}: after a transverse wave shock collision, the strength of the transverse wave weakens as it propagates along the front. If the spacing between shock collisions is too large (cell size), then the transverse shocks may weaken to the extent that the lead shock temperature or that behind the transverse waves is not raised above T{sub b}, losing chemical energy to

  15. Modified branched-chain amino acid pathways give rise to acyl acids of sucrose esters exuded from tobacco leaf trichomes.

    PubMed

    Kandra, G; Severson, R; Wagner, G J

    1990-03-10

    A major diversion of carbon from branched-chain amino acid biosynthesis/catabolism to form acyl moieties of sucrose esters (6-O-acetyl-2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-beta-D- fructofuranosides) was observed to be associated with specialized trichome head cells which secrete large amounts of sucrose esters. Surface chemistry and acetyl and acyl substituent groups of tobacco (T.I. 1068) sucrose esters were identified and quantified by gas chromatography/mass spectrometry. Sucrose esters were prominent surface constituents and 3-methylvaleric acid, 2- and 3-methylbutyric acid, and methylpropionic acid accounted for 60%, 25% and 9%, respectively, of total C3--C7 acyl substituents. Radiolabeled Thr, Ile, Val, Leu, pyruvate and Asp, metabolites of branched-chain amino acid pathways, were compared with radioactively labeled acetate and sucrose as donors of carbon to sucrose, acetyl and acyl components of sucrose esters using epidermal peels with undisturbed trichomes. Preparations of biosynthetically competent trichome heads (site of sucrose ester formation) were also examined. Results indicate that 3-methylvaleryl and 2-methylbutyryl groups are derived from the Thr pathway of branched-chain amino acid metabolism, 3-methylbutyryl and methylpropionyl groups are formed via the pyruvate pathway, and that acetyl groups are principally formed directly via acetyl-CoA. Arguments are presented which rule out participation of fatty acid synthase in the formation of prominent acyl acids. Results suggest that the shunting of carbon away from the biosynthesis of Val, Leu and Ile may be due to a low level of amino acid utilization in protein synthesis in specialized glandular head cells of trichomes. This would result in the availability of corresponding oxo acids for CoA activation and esterification to form sucrose esters. Preliminary evidence was found for the involvement of cycling reactions in oxo-acid-chain lengthening and for utilization of pyruvate-derived 2

  16. Associations between plasma branched-chain amino acids, β-aminoisobutyric acid and body composition.

    PubMed

    Rietman, Annemarie; Stanley, Takara L; Clish, Clary; Mootha, Vamsi; Mensink, Marco; Grinspoon, Steven K; Makimura, Hideo

    2016-01-01

    Plasma branched-chain amino acids (BCAA) are elevated in obesity and associated with increased cardiometabolic risk. β-Aminoisobutyric acid (B-AIBA), a recently identified small molecule metabolite, is associated with decreased cardiometabolic risk. Therefore, we investigated the association of BCAA and B-AIBA with each other and with detailed body composition parameters, including abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). A cross-sectional study was carried out with lean (n 15) and obese (n 33) men and women. Detailed metabolic evaluations, including measures of body composition, insulin sensitivity and plasma metabolomics were completed. Plasma BCAA were higher (1·6 (se 0·08) (×10(7)) v. 1·3 (se 0·06) (×10(7)) arbitrary units; P = 0·005) in obese v. lean subjects. BCAA were positively associated with VAT (R 0·49; P = 0·0006) and trended to an association with SAT (R 0·29; P = 0·052). The association between BCAA and VAT, but not SAT, remained significant after controlling for age, sex and race on multivariate modelling (P < 0·05). BCAA were also associated with parameters of insulin sensitivity (Matsuda index: R -0·50, P = 0·0004; glucose AUC: R 0·53, P < 0·001). BCAA were not associated with B-AIBA (R -0·04; P = 0·79). B-AIBA was negatively associated with SAT (R -0·37; P = 0·01) but only trended to an association with VAT (R 0·27; P = 0·07). However, neither relationship remained significant after multivariate modelling (P > 0·05). Plasma B-AIBA was associated with parameters of insulin sensitivity (Matsuda index R 0·36, P = 0·01; glucose AUC: R -0·30, P = 0·04). Plasma BCAA levels were positively correlated with VAT and markers of insulin resistance. The results suggest a possible complex role of adipose tissue in BCAA homeostasis and insulin resistance. PMID:27313851

  17. Neutron reflectometry of quaternary gemini surfactants as a function of alkyl chain length: anomalies arising from ion association and premicellar aggregation.

    PubMed

    Li, Pei Xun; Dong, Chu Chuan; Thomas, Robert K; Penfold, J; Wang, Yilin

    2011-03-15

    We have measured the structure and properties of a series of dicationic quaternary ammonium compounds α,ω-bis(N-alkyl dimethyl ammonium)hexane halides (Cn-C6-Cn) for values of the alkyl chain length n of 8, 9, 10, 11, 12, and 16, and a series of α,ω-bis(N-alkyl dimethyl ammonium)diethylether halides (Cn-C2OC2-Cn) for values of n of 8, 12, and 16, as well as C8-C12-C8 and C12-C10-C12 at the air/water interface. Although the critical micelle concentration (CMC) in the two series decreases in the normal way, that is, logarithmically, with increasing chain length, the limiting surface tension at the CMC and the limiting area per molecule both increase with chain length, in the opposite direction from comparable single chain surfactants. The structures of the surface layers, which were determined by neutron reflectometry, indicate that the anomalous behavior of the surface tension and area are probably caused by poor packing of the gemini side chains between adjacent molecules. Comparison of the directly determined surface coverage using neutron reflectometry and the apparent coverage determined by application of the Gibbs equation to surface tension data gives an experimental measurement of the prefactor in the Gibbs equation, which should be 3 for these geminis. It was found to vary from about 3 for the two C16 geminis down to about 1.5 for the two C8 geminis. We have devised a simple quantitative model that explains this variation and earlier observations that the Gibbs prefactor for C12-Cn-C12 (n varying from 3 to 12) is around 2. The model is consistent with the conductivity, NMR, and fluorescence measurements of other authors. This model shows that both dimerization and ion association are required to explain the surface tension behavior of cationic gemini bromide surfactants and that, in many cases, the prefactor itself varies with concentration.

  18. δ-Methyl Branching in the Side Chain Makes the Difference: Access to Room-Temperature Discotics.

    PubMed

    Kirres, Jochen; Knecht, Friederike; Seubert, Philipp; Baro, Angelika; Laschat, Sabine

    2016-04-18

    Although discotic liquid crystals are attractive functional materials, their use in electronic devices is often restricted by high melting and clearing points. Among the promising candidates for applications are [15]crown-5 ether-based liquid crystals with peripheral n-alkoxy side chains, which, however, still have melting points above room temperature. To overcome this problem, a series of o-terphenyl and triphenylene [15]crown-5 ether derivatives was prepared in which δ-methyl-branched alkoxy side chains of varying lengths substitute the peripheral linear alkoxy chains. The mesomorphic properties of the novel crown ethers were studied by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. δ-Methyl branching indeed lowers melting points resulting in room-temperature hexagonal columnar mesophases. The mesophase widths, which ranged from 87 to 30 K for o-terphenyls, significantly increased to 106-147 K for the triphenylenes depending on the chain lengths, revealing the beneficial effect of a flat mesogen, due to improved π-π interactions.

  19. δ-Methyl Branching in the Side Chain Makes the Difference: Access to Room-Temperature Discotics.

    PubMed

    Kirres, Jochen; Knecht, Friederike; Seubert, Philipp; Baro, Angelika; Laschat, Sabine

    2016-04-18

    Although discotic liquid crystals are attractive functional materials, their use in electronic devices is often restricted by high melting and clearing points. Among the promising candidates for applications are [15]crown-5 ether-based liquid crystals with peripheral n-alkoxy side chains, which, however, still have melting points above room temperature. To overcome this problem, a series of o-terphenyl and triphenylene [15]crown-5 ether derivatives was prepared in which δ-methyl-branched alkoxy side chains of varying lengths substitute the peripheral linear alkoxy chains. The mesomorphic properties of the novel crown ethers were studied by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. δ-Methyl branching indeed lowers melting points resulting in room-temperature hexagonal columnar mesophases. The mesophase widths, which ranged from 87 to 30 K for o-terphenyls, significantly increased to 106-147 K for the triphenylenes depending on the chain lengths, revealing the beneficial effect of a flat mesogen, due to improved π-π interactions. PMID:26853226

  20. Origin of Broad Visible Emission from Branched Polysilane and Polygermane Chains

    NASA Astrophysics Data System (ADS)

    Watanabe, Akira; Sato, Takaaki; Matsuda, Minoru

    2001-11-01

    The emission properties of branched polysilane and polygermane are studied using time-resolved emission spectroscopy. As branched polymers, the organosilicon cluster (OSI) and organogermanium cluster (OGE) are investigated, which are prepared from tetrachlorosilane and tetrachlorogermane, respectively, and have a hyperbranched structure. The broad visible emissions of OSI and OGE are explained by the energy diagram based on a configuration coordinate model, and the excited states are attributed to a localized state around the branching point. The molecular orbital (MO) calculation suggested the formation of a localized state by the distortion around the branching point in the excited state. The potential barrier for the nonradiative relaxation process was determined from the temperature dependence of the emission lifetime.

  1. Linear and branched alkyl-esters and amides of gallic acid and other (mono-, di- and tri-) hydroxy benzoyl derivatives as promising anti-HCV inhibitors.

    PubMed

    Rivero-Buceta, Eva; Carrero, Paula; Doyagüez, Elisa G; Madrona, Andrés; Quesada, Ernesto; Camarasa, María José; Peréz-Pérez, María Jesús; Leyssen, Pieter; Paeshuyse, Jan; Balzarini, Jan; Neyts, Johan; San-Félix, Ana

    2015-03-01

    Linear and branched compounds that contain two, three or five units of galloyl (3,4,5-trihydroxybenzoyl) or its isomer 2,3,4-trihydroxybenzoyl, as well as other mono- or dihydroxybenzoyl moieties have been synthesized. These molecules have been evaluated for their in vitro inhibitory effects against a wide panel of viruses showing preferential activity against HIV and HCV. Our structure-activity relationship studies demonstrated that the 2,3,4-trihydroxybenzoyl moiety provides better antiviral activities than the galloyl (3,4,5-trihydroxybenzoyl) moiety that is present in natural green tea catechins. This observation can be of interest for the further rational exploration of compounds with anti-HCV/HIV properties. The most notable finding with respect to HIV is that the tripodal compounds 43 and 45, with three 2,3,4-trihydroxybenzoyl moieties, showed higher activities than linear compounds with only one or two. With respect to HCV, the linear compounds, 52 and 41, containing a 12 polymethylene chain and two 2,3 di- or 2,3,4 tri-hydroxybenzoyl groups respectively at the ends of the molecule showed good antiviral efficiency. Furthermore, the anti-HCV activity of both compounds was observed at concentrations well below the cytotoxicity threshold. A representative member of these compounds, 41, showed that the anti-HCV activity was largely independent of the genetic make-up of the HCV subgenomic replicon and cell lines used.

  2. Linear and branched alkyl-esters and amides of gallic acid and other (mono-, di- and tri-) hydroxy benzoyl derivatives as promising anti-HCV inhibitors.

    PubMed

    Rivero-Buceta, Eva; Carrero, Paula; Doyagüez, Elisa G; Madrona, Andrés; Quesada, Ernesto; Camarasa, María José; Peréz-Pérez, María Jesús; Leyssen, Pieter; Paeshuyse, Jan; Balzarini, Jan; Neyts, Johan; San-Félix, Ana

    2015-03-01

    Linear and branched compounds that contain two, three or five units of galloyl (3,4,5-trihydroxybenzoyl) or its isomer 2,3,4-trihydroxybenzoyl, as well as other mono- or dihydroxybenzoyl moieties have been synthesized. These molecules have been evaluated for their in vitro inhibitory effects against a wide panel of viruses showing preferential activity against HIV and HCV. Our structure-activity relationship studies demonstrated that the 2,3,4-trihydroxybenzoyl moiety provides better antiviral activities than the galloyl (3,4,5-trihydroxybenzoyl) moiety that is present in natural green tea catechins. This observation can be of interest for the further rational exploration of compounds with anti-HCV/HIV properties. The most notable finding with respect to HIV is that the tripodal compounds 43 and 45, with three 2,3,4-trihydroxybenzoyl moieties, showed higher activities than linear compounds with only one or two. With respect to HCV, the linear compounds, 52 and 41, containing a 12 polymethylene chain and two 2,3 di- or 2,3,4 tri-hydroxybenzoyl groups respectively at the ends of the molecule showed good antiviral efficiency. Furthermore, the anti-HCV activity of both compounds was observed at concentrations well below the cytotoxicity threshold. A representative member of these compounds, 41, showed that the anti-HCV activity was largely independent of the genetic make-up of the HCV subgenomic replicon and cell lines used. PMID:25617695

  3. Asymptotic study of pulsating evolution of overdriven and CJ detonation with a chain-branching kinetics model

    SciTech Connect

    Short, Mark; Chliquete, Carlos

    2011-01-20

    The pulsating dynamics of gaseous detonations with a model two-step chain-branching kinetic mechanism are studied both numerically and asymptotically. The model studied here was also used in [4], [3] and [2] and mimics the attributes of some chain-branching reaction mechanisms. Specifically, the model comprises a chain-initiationlbranching zone with an Arrhenius temperature-sensitive rate behind the detonation shock where fuel is converted into chain-radical with no heat release. This is followed by a chain-termination zone having a temperature insensitive rate where the exothermic heat of reaction is released. The lengths of these two zones depend on the relative rates of each stage. It was determined in [4] and [3] via asymptotic and numerical analysis that the ratio of the length of the chain-branching zone to that of the chain-initation zone relative to the size of the von Neumann state scaled activation energy in the chain initiation/branching zone has a primary influence of the stability of one-dimensional pulsating instability behavior for this model. In [2], the notion of a specific stability parameter related to this ratio was proposed that determines the boundary between stable and unstable waves. In [4], a slow-time varying asymptotic study was conducted of pulsating instability of Chapman-Jouguet (CJ) detonations with the above two-step rate model, assuming a large activation energy for the chain-initiation zone and a chain-termination zone longer than the chain-initiation zone. Deviations D{sub n}{sup (1)} ({tau}) of the detonation velocity from Chapman-Jouguet were of the order of the non-dimensional activation energy. Solutions were sought for a pulsation timescale of the order of the non-dimensional activation energy times the particle transit time through the induction zone. On this time-scale, the evolution of the chain-initation zone is quasi-steady. In [4], a time-dependent non-linear evolution equation for D{sub n}{sup (1)} ({tau}) was then

  4. Enhanced production of branched-chain fatty acids by replacing β-ketoacyl-(acyl-carrier-protein) synthase III (FabH).

    PubMed

    Jiang, Wen; Jiang, Yanfang; Bentley, Gayle J; Liu, Di; Xiao, Yi; Zhang, Fuzhong

    2015-08-01

    Branched-chain fatty acids (BCFAs) are important precursors for the production of advanced biofuels with improved cold-flow properties. Previous efforts in engineering type II fatty acid synthase (FAS) for BCFA production suffered from low titers and/or the co-production of a large amount of straight-chain fatty acids (SCFAs), making it nearly impossible for further conversion of BCFAs to branched biofuels. Synthesis of both SCFAs and BCFAs requires FabH, the only β-ketoacyl-(acyl-carrier-protein) synthase in Escherichia coli that catalyzes the initial condensation reaction between malonyl-ACP and a short-chain acyl-CoA. In this study, we demonstrated that replacement of the acetyl-CoA-specific E. coli FabH with a branched-chain-acyl-CoA-specific FabH directed the flux to the synthesis of BCFAs, resulting in a significant enhancement in BCFA titer compared to a strain containing both acetyl-CoA- and branched-chain-acyl-CoA-specific FabHs. We further demonstrated that the composition of BCFAs can be tuned by engineering the upstream pathway to control the supply of different branched-chain acyl-CoAs, leading to the production either even-chain-iso-, odd-chain-iso-, or odd-chain-anteiso-BCFAs separately. Overall, the top-performing strain from this study produced BCFAs at 126 mg/L, comprising 52% of the total free fatty acids.

  5. Enhanced production of branched-chain fatty acids by replacing β-ketoacyl-(acyl-carrier-protein) synthase III (FabH).

    PubMed

    Jiang, Wen; Jiang, Yanfang; Bentley, Gayle J; Liu, Di; Xiao, Yi; Zhang, Fuzhong

    2015-08-01

    Branched-chain fatty acids (BCFAs) are important precursors for the production of advanced biofuels with improved cold-flow properties. Previous efforts in engineering type II fatty acid synthase (FAS) for BCFA production suffered from low titers and/or the co-production of a large amount of straight-chain fatty acids (SCFAs), making it nearly impossible for further conversion of BCFAs to branched biofuels. Synthesis of both SCFAs and BCFAs requires FabH, the only β-ketoacyl-(acyl-carrier-protein) synthase in Escherichia coli that catalyzes the initial condensation reaction between malonyl-ACP and a short-chain acyl-CoA. In this study, we demonstrated that replacement of the acetyl-CoA-specific E. coli FabH with a branched-chain-acyl-CoA-specific FabH directed the flux to the synthesis of BCFAs, resulting in a significant enhancement in BCFA titer compared to a strain containing both acetyl-CoA- and branched-chain-acyl-CoA-specific FabHs. We further demonstrated that the composition of BCFAs can be tuned by engineering the upstream pathway to control the supply of different branched-chain acyl-CoAs, leading to the production either even-chain-iso-, odd-chain-iso-, or odd-chain-anteiso-BCFAs separately. Overall, the top-performing strain from this study produced BCFAs at 126 mg/L, comprising 52% of the total free fatty acids. PMID:25788017

  6. Interactions of /sup 14/N:/sup 15/N stearic acid spin-label pairs: effects of host lipid alkyl chain length and unsaturation

    SciTech Connect

    Feix, J.B.; Yin, J.J.; Hyde, J.S.

    1987-06-30

    Electron-electron double resonance (ELDOR) and saturation recovery electron paramagnetic resonance (EPR) spectroscopy have been employed to examine the interactions of /sup 14/N:/sup 15/N stearic acid spin-label pairs in fluid-phase model membrane bilayers composed of a variety of phospholipids. The (/sup 14/N)-16-doxylstearate:(/sup 15/N)-16-doxylstearate (16:16) pair was utilized to measure lateral diffusion of the spin-labels, while the (/sup 14/N)-16-doxylstearate:(/sup 15/N)-5-doxylstearate (16:5) pair provided information on vertical fluctuations of the 16-doxylstearate nitroxide moiety toward the membrane surface. Three saturated host lipids of varying alkyl chain length (dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC), and distearoylphosphatidylcholine (DSPC)), an ..cap alpha..-saturated, ..beta..-unsaturated lipid (1-palmitoyl-2-oleoylphosphatidylcholine (POPC)), and phosphatidylcholine from a natural source (egg yolk phosphatidylcholine (egg PC)) were utilized as host lipids. Lateral diffusion of the stearic acid spin-labels was only slightly affected by alkyl chain length at a given reduced temperature (T/sub r/) in the saturated host lipids but was significantly decreased in POPC at the same T/sub r/. Lateral diffusion in DMPC, POPC, and egg PC was quite similar at 37/sup 0/C. A strong correlation was noted between lateral diffusion constants and rotational mobility of (/sup 14/N)-16-doxylstearate. Vertical fluctuations were likewise only slightly influenced by alklyl chain length but were strongly diminished in POPC and egg PC relative to the saturated systems. This diminution of the 16:5 interaction was observed even under conditions where no differences were discernible by conventional EPR.

  7. Experimental and computational studies on the unusual substrate specificity of branched-chain amino acid aminotransferase from Thermoproteus uzoniensis.

    PubMed

    Bezsudnova, Ekaterina Yu; Stekhanova, Tatiana N; Suplatov, Dmitry A; Mardanov, Andrey V; Ravin, Nikolai V; Popov, Vladimir O

    2016-10-01

    PLP-Dependent fold-type IV branched-chain amino acid aminotransferases (BCATs) from archaea have so far been poorly characterized. A new BCAT from the hyperthermophilic archaeon Thermoproteus uzoniensis (TUZN1299) has been studied. TUZN1299 was found to be highly active toward branched-chain amino acids (BCAAs), positively charged amino acids, l-methionine, l-threonine, l-homoserine, l-glutamine, as well as toward 2-oxobutyrate and keto analogs of BCAAs, whereas l-glutamate and α-ketoglutarate were not converted in the overall reaction. According to stopped-flow experiments, the enzyme showed the highest specificity to BCAAs and their keto analogs. In order to explain the molecular mechanism of the unusual specificity of TUZN1299, bioinformatic analysis was implemented to identify the subfamily-specific positions in the aminotransferase class IV superfamily of enzymes. The role of the selected residues in binding of various ligands in the active site was further studied using molecular modeling. The results indicate that Glu188 forms a novel binding site for positively charged and polar side-chains of amino acids. Lack of accommodation for α-ketoglutarate and l-glutamate is due to the unique orientation and chemical properties of residues 102-106 in the loop forming the A-pocket. The likely functional roles of TUZN1299 in cellular metabolism - in the synthesis and degradation of BCAAs - are discussed. PMID:27523731

  8. Experimental and computational studies on the unusual substrate specificity of branched-chain amino acid aminotransferase from Thermoproteus uzoniensis.

    PubMed

    Bezsudnova, Ekaterina Yu; Stekhanova, Tatiana N; Suplatov, Dmitry A; Mardanov, Andrey V; Ravin, Nikolai V; Popov, Vladimir O

    2016-10-01

    PLP-Dependent fold-type IV branched-chain amino acid aminotransferases (BCATs) from archaea have so far been poorly characterized. A new BCAT from the hyperthermophilic archaeon Thermoproteus uzoniensis (TUZN1299) has been studied. TUZN1299 was found to be highly active toward branched-chain amino acids (BCAAs), positively charged amino acids, l-methionine, l-threonine, l-homoserine, l-glutamine, as well as toward 2-oxobutyrate and keto analogs of BCAAs, whereas l-glutamate and α-ketoglutarate were not converted in the overall reaction. According to stopped-flow experiments, the enzyme showed the highest specificity to BCAAs and their keto analogs. In order to explain the molecular mechanism of the unusual specificity of TUZN1299, bioinformatic analysis was implemented to identify the subfamily-specific positions in the aminotransferase class IV superfamily of enzymes. The role of the selected residues in binding of various ligands in the active site was further studied using molecular modeling. The results indicate that Glu188 forms a novel binding site for positively charged and polar side-chains of amino acids. Lack of accommodation for α-ketoglutarate and l-glutamate is due to the unique orientation and chemical properties of residues 102-106 in the loop forming the A-pocket. The likely functional roles of TUZN1299 in cellular metabolism - in the synthesis and degradation of BCAAs - are discussed.

  9. Short branched-chain C6 carboxylic acids result in increased growth, novel 'unnatural' fatty acids and increased membrane fluidity in a Listeria monocytogenes branched-chain fatty acid-deficient mutant.

    PubMed

    Sen, Suranjana; Sirobhushanam, Sirisha; Hantak, Michael P; Lawrence, Peter; Brenna, J Thomas; Gatto, Craig; Wilkinson, Brian J

    2015-10-01

    Listeria monocytogenes is a psychrotolerant food borne pathogen, responsible for the high fatality disease listeriosis, and expensive food product recalls. Branched-chain fatty acids (BCFAs) of the membrane play a critical role in providing appropriate membrane fluidity and optimum membrane biophysics. The fatty acid composition of a BCFA-deficient mutant is characterized by high amounts of straight-chain fatty acids and even-numbered iso fatty acids, in contrast to the parent strain where odd-numbered anteiso fatty acids predominate. The presence of 2-methylbutyrate (C5) stimulated growth of the mutant at 37°C and restored growth at 10°C along with the content of odd-numbered anteiso fatty acids. The C6 branched-chain carboxylic acids 2-ethylbutyrate and 2-methylpentanoate also stimulated growth to a similar extent as 2-methylbutyrate. However, 3-methylpentanoate was ineffective in rescuing growth. 2-Ethylbutyrate and 2-methylpentanoate led to novel major fatty acids in the lipid profile of the membrane that were identified as 12-ethyltetradecanoic acid and 12-methylpentadecanoic acid respectively. Membrane anisotropy studies indicated that growth of strain MOR401 in the presence of these precursors increased its membrane fluidity to levels of the wild type. Cells supplemented with 2-methylpentanoate or 2-ethylbutyrate at 10°C shortened the chain length of novel fatty acids, thus showing homeoviscous adaptation. These experiments use the mutant as a tool to modulate the membrane fatty acid compositions through synthetic precursor supplementation, and show how existing enzymes in L. monocytogenes adapt to exhibit non-native activity yielding unique 'unnatural' fatty acid molecules, which nevertheless possess the correct biophysical properties for proper membrane function in the BCFA-deficient mutant.

  10. Short branched-chain C6 carboxylic acids result in increased growth, novel 'unnatural' fatty acids and increased membrane fluidity in a Listeria monocytogenes branched-chain fatty acid-deficient mutant.

    PubMed

    Sen, Suranjana; Sirobhushanam, Sirisha; Hantak, Michael P; Lawrence, Peter; Brenna, J Thomas; Gatto, Craig; Wilkinson, Brian J

    2015-10-01

    Listeria monocytogenes is a psychrotolerant food borne pathogen, responsible for the high fatality disease listeriosis, and expensive food product recalls. Branched-chain fatty acids (BCFAs) of the membrane play a critical role in providing appropriate membrane fluidity and optimum membrane biophysics. The fatty acid composition of a BCFA-deficient mutant is characterized by high amounts of straight-chain fatty acids and even-numbered iso fatty acids, in contrast to the parent strain where odd-numbered anteiso fatty acids predominate. The presence of 2-methylbutyrate (C5) stimulated growth of the mutant at 37°C and restored growth at 10°C along with the content of odd-numbered anteiso fatty acids. The C6 branched-chain carboxylic acids 2-ethylbutyrate and 2-methylpentanoate also stimulated growth to a similar extent as 2-methylbutyrate. However, 3-methylpentanoate was ineffective in rescuing growth. 2-Ethylbutyrate and 2-methylpentanoate led to novel major fatty acids in the lipid profile of the membrane that were identified as 12-ethyltetradecanoic acid and 12-methylpentadecanoic acid respectively. Membrane anisotropy studies indicated that growth of strain MOR401 in the presence of these precursors increased its membrane fluidity to levels of the wild type. Cells supplemented with 2-methylpentanoate or 2-ethylbutyrate at 10°C shortened the chain length of novel fatty acids, thus showing homeoviscous adaptation. These experiments use the mutant as a tool to modulate the membrane fatty acid compositions through synthetic precursor supplementation, and show how existing enzymes in L. monocytogenes adapt to exhibit non-native activity yielding unique 'unnatural' fatty acid molecules, which nevertheless possess the correct biophysical properties for proper membrane function in the BCFA-deficient mutant. PMID:26225744

  11. Acute and chronic administration of the branched-chain amino acids decreases nerve growth factor in rat hippocampus.

    PubMed

    Scaini, Giselli; Mello-Santos, Lis Mairá; Furlanetto, Camila B; Jeremias, Isabela C; Mina, Francielle; Schuck, Patrícia F; Ferreira, Gustavo C; Kist, Luiza W; Pereira, Talita C B; Bogo, Maurício R; Streck, Emilio L

    2013-12-01

    Maple syrup urine disease (MSUD) is a neurometabolic disorder caused by deficiency of the activity of the mitochondrial enzyme complex branched-chain α-keto acid dehydrogenase leading to accumulation of the branched-chain amino acids (BCAA) and their corresponding branched-chain α-keto acids. In this study, we examined the effects of acute and chronic administration of BCAA on protein levels and mRNA expression of nerve growth factor (NGF) considering that patients with MSUD present neurological dysfunction and cognitive impairment. Considering previous observations, it is suggested that oxidative stress may be involved in the pathophysiology of the neurological dysfunction of MSUD. We also investigated the influence of antioxidant treatment (N-acetylcysteine and deferoxamine) in order to verify the influence of oxidative stress in the modulation of NGF levels. Our results demonstrated decreased protein levels of NGF in the hippocampus after acute and chronic administration of BCAA. In addition, we showed a significant decrease in the expression of ngf in the hippocampus only following acute administration in 10-day-old rats. Interestingly, antioxidant treatment was able to prevent the decrease in NGF levels by increasing ngf expression. In conclusion, the results suggest that BCAA is involved in the regulation of NGF in the developing rat. Thus, it is possible that alteration of neurotrophin levels during brain maturation could be of pivotal importance in the impairment of cognition provoked by BCAA. Moreover, the decrease in NGF levels was prevented by antioxidant treatment, reinforcing that the hypothesis of oxidative stress can be an important pathophysiological mechanism underlying the brain damage observed in MSUD. PMID:23559405

  12. Effect of Structure on Transport Properties (Viscosity, Ionic Conductivity, and Self-Diffusion Coefficient) of Aprotic Heterocyclic Anion (AHA) Room Temperature Ionic Liquids. 2. Variation of Alkyl Chain Length in the Phosphonium Cation.

    PubMed

    Sun, Liyuan; Morales-Collazo, Oscar; Xia, Han; Brennecke, Joan F

    2016-06-30

    A series of room-temperature ionic liquids (ILs) composed of triethyl(alkyl)phosphonium cations paired with three different aprotic heterocyclic anions (AHAs) (alkyl = butyl ([P2224](+)) and octyl ([P2228](+))) were prepared to investigate the effect of cationic alkyl chain length on transport properties. The transport properties and density of these ILs were measured from 283.15 to 343.15 K at ambient pressure. The dependence of the transport properties (viscosity, ionic conductivity, diffusivity, and molar conductivity) on temperature can be described by the Vogel-Fulcher-Tamman (VFT) equation. The ratio of the molar conductivity obtained from the molar concentration and ionic conductivity measurements to that calculated from self-diffusion coefficients (measured by pulsed gradient spin-echo nuclear magnetic resonance spectroscopy) using the Nernst-Einstein equation was used to quantify the ionicity of these ILs. The molar conductivity ratio decreases with increasing number of carbon atoms in the alkyl chain, indicating that the reduced Coulombic interactions resulting from lower density are more than balanced by the increased van der Waals interactions between the alkyl chains. The results of this study may provide insight into the design of ILs with enhanced dynamics that may be suitable as electrolytes in lithium ion batteries and other electrochemical applications.

  13. Volatile profiling reveals intracellular metabolic changes in Aspergillus parasiticus: veA regulates branched chain amino acid and ethanol metabolism

    PubMed Central

    2010-01-01

    Background Filamentous fungi in the genus Aspergillus produce a variety of natural products, including aflatoxin, the most potent naturally occurring carcinogen known. Aflatoxin biosynthesis, one of the most highly characterized secondary metabolic pathways, offers a model system to study secondary metabolism in eukaryotes. To control or customize biosynthesis of natural products we must understand how secondary metabolism integrates into the overall cellular metabolic network. By applying a metabolomics approach we analyzed volatile compounds synthesized by Aspergillus parasiticus in an attempt to define the association of secondary metabolism with other metabolic and cellular processes. Results Volatile compounds were examined using solid phase microextraction - gas chromatography/mass spectrometry. In the wild type strain Aspergillus parasiticus SU-1, the largest group of volatiles included compounds derived from catabolism of branched chain amino acids (leucine, isoleucine, and valine); we also identified alcohols, esters, aldehydes, and lipid-derived volatiles. The number and quantity of the volatiles produced depended on media composition, time of incubation, and light-dark status. A block in aflatoxin biosynthesis or disruption of the global regulator veA affected the volatile profile. In addition to its multiple functions in secondary metabolism and development, VeA negatively regulated catabolism of branched chain amino acids and synthesis of ethanol at the transcriptional level thus playing a role in controlling carbon flow within the cell. Finally, we demonstrated that volatiles generated by a veA disruption mutant are part of the complex regulatory machinery that mediates the effects of VeA on asexual conidiation and sclerotia formation. Conclusions 1) Volatile profiling provides a rapid, effective, and powerful approach to identify changes in intracellular metabolic networks in filamentous fungi. 2) VeA coordinates the biosynthesis of secondary

  14. Uncoupling and Toxic Action of Alkyltriphenylphosphonium Cations on Mitochondria and the Bacterium Bacillus subtilis as a Function of Alkyl Chain Length.

    PubMed

    Khailova, L S; Nazarov, P A; Sumbatyan, N V; Korshunova, G A; Rokitskaya, T I; Dedukhova, V I; Antonenko, Yu N; Skulachev, V P

    2015-12-01

    A series of permeating cations based on alkyl derivatives of triphenylphosphonium (C(n)-TPP(+)) containing linear hydrocarbon chains (butyl, octyl, decyl, and dodecyl) was investigated in systems of isolated mitochondria, bacteria, and liposomes. In contrast to some derivatives (esters) of rhodamine-19, wherein butyl rhodamine possessed the maximum activity, in the case of C(n)-TPP a stimulatory effect on mitochondrial respiration steadily increased with growing length of the alkyl radical. Tetraphenylphosphonium and butyl-TPP(+) at a dose of several hundred micromoles exhibited an uncoupling effect, which might be related to interaction between C(n)-TPP(+) and endogenous fatty acids and induction of their own cyclic transfer, resulting in transport of protons across the mitochondrial membrane. Such a mechanism was investigated by measuring efflux of carboxyfluorescein from liposomes influenced by C(n)-TPP(+). Experiments with bacteria demonstrated that dodecyl-TPP(+), decyl-TPP(+), and octyl-TPP(+) similarly to quinone-containing analog (SkQ1) inhibited growth of the Gram-positive bacterium Bacillus subtilis, wherein the inhibitory effect was upregulated with growing lipophilicity. These cations did not display toxic effect on growth of the Gram-negative bacterium Escherichia coli. It is assumed that the difference in toxic action on various bacterial species might be related to different permeability of bacterial coats for the examined triphenylphosphonium cations. PMID:26638684

  15. Chain-Length Distribution and Hydrogen Isotopic Fraction of n-alkyl Lipids in Aquatic and Terrestrial Plants: Implications for Paleoclimate Reconstructions

    NASA Astrophysics Data System (ADS)

    Gao, L.; Littlejohn, S.; Hou, J.; Toney, J.; Huang, Y.

    2008-12-01

    Recent studies demonstrate that in lacustrine sediments, aquatic plant lipids (e.g., C22-fatty acid) record lake water D/H ratio variation, while long-chain fatty acids (C26-C32, major components of terrestrial plant leaf waxes), record D/H ratios of precipitation (especially in arid regions). However, there are insufficient literature data for the distribution and hydrogen isotopic fractionation of n-alkyl lipids in aquatic and terrestrial plants. In this study, we determined the chain-length distributions and D/H ratios of n-alkyl lipids from 17 aquatic plant species (9 emergent, 4 floating and 4 submerge species) and 13 terrestrial plant species (7 grasses and 6 trees) from Blood Pond, Massachusetts. Our results are consistent with previous studies and provide a solid basis for the paleoclimatic reconstruction using D/H ratios of aquatic and terrestrial plant biomarkers. In addition, systematic hydrogen isotopic analyses on leaf waxes, leaf, stem and soil waters from trees and grasses significantly advance our understanding of our previously observed large D/H ratio difference between tree and grass leaf waxes. Our data indicate that the observed difference is not due to differences in leaf water D/H ratios. In comparison with grasses, trees use greater proportion of D-enriched residual or stored carbohydrates (as opposed to current photosynthetic carbohydrates) for leaf wax biosynthesis, resulting in higher leaf wax D/H ratios. The residual carbohydrates are enriched in deuterium because of the preferential consumption of light-hydrogen substrates during plant metabolism.

  16. Control over the Self-Assembly Modes of Pt(II) Complexes by Alkyl Chain Variation: From Slipped to Parallel π-Stacks.

    PubMed

    Allampally, Naveen Kumar; Mayoral, María José; Chansai, Sarayute; Lagunas, María Cristina; Hardacre, Christopher; Stepanenko, Vladimir; Albuquerque, Rodrigo Q; Fernández, Gustavo

    2016-06-01

    We report the self-assembly of a new family of hydrophobic, bis(pyridyl) Pt(II) complexes featuring an extended oligophenyleneethynylene-derived π-surface appended with six long (dodecyloxy (2)) or short (methoxy (3)) side groups. Complex 2, containing dodecyloxy chains, forms fibrous assemblies with a slipped arrangement of the monomer units (dPt⋅⋅⋅Pt ≈14 Å) in both nonpolar solvents and the solid state. Dispersion-corrected PM6 calculations suggest that this organization is driven by cooperative π-π, C-H⋅⋅⋅Cl and π-Pt interactions, which is supported by EXAFS and 2D NMR spectroscopic analysis. In contrast, nearly parallel π-stacks (dPt⋅⋅⋅Pt ≈4.4 Å) stabilized by multiple π-π and C-H⋅⋅⋅Cl contacts are obtained in the crystalline state for 3 lacking long side chains, as shown by X-ray analysis and PM6 calculations. Our results reveal not only the key role of alkyl chain length in controlling self-assembly modes but also show the relevance of Pt-bound chlorine ligands as new supramolecular synthons.

  17. Neutral Pectin side chains of Amaranth (Amaranthus hypochondriacus) contain long, partially branched Arabinans and short galactans, both with terminal arabinopyranoses.

    PubMed

    Wefers, Daniel; Tyl, Catrin E; Bunzel, Mirko

    2015-01-21

    Amaranth is a pseudocereal of high nutritional value, including a high dietary fiber content. Amaranth dietary fiber was suggested to contain large amounts of neutral rhamnogalacturonan I side chains. In this study, endo-arabinanase and endo-galactanase were used to liberate arabinan and galactan oligosaccharides from amaranth fiber. The liberated oligosaccharides were identified by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and HPLC-MS(n) using standard compounds, which were isolated from amaranth, sugar beet, potato, and red clover sprouts and characterized by one- and two-dimensional NMR spectroscopy. It was demonstrated that insoluble amaranth arabinans have linear and branched areas, with the O-3 position being the dominant branching point. Minor amounts of branches at position O-2 and double substitution were also found. Amaranth arabinans were also demonstrated to contain terminal α-(1→5)-linked l-arabinopyranose units. In addition, it was evidenced that galactans from amaranth seeds are composed of β-(1→4)-linked d-galactopyranose units, which can also be terminated with l-arabinopyranose units. In direct comparison to structural elucidation of amaranth fiber by using methylation analysis, the advantage of the enzymatic approach over methylation analysis was demonstrated.

  18. Neutral Pectin side chains of Amaranth (Amaranthus hypochondriacus) contain long, partially branched Arabinans and short galactans, both with terminal arabinopyranoses.

    PubMed

    Wefers, Daniel; Tyl, Catrin E; Bunzel, Mirko

    2015-01-21

    Amaranth is a pseudocereal of high nutritional value, including a high dietary fiber content. Amaranth dietary fiber was suggested to contain large amounts of neutral rhamnogalacturonan I side chains. In this study, endo-arabinanase and endo-galactanase were used to liberate arabinan and galactan oligosaccharides from amaranth fiber. The liberated oligosaccharides were identified by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and HPLC-MS(n) using standard compounds, which were isolated from amaranth, sugar beet, potato, and red clover sprouts and characterized by one- and two-dimensional NMR spectroscopy. It was demonstrated that insoluble amaranth arabinans have linear and branched areas, with the O-3 position being the dominant branching point. Minor amounts of branches at position O-2 and double substitution were also found. Amaranth arabinans were also demonstrated to contain terminal α-(1→5)-linked l-arabinopyranose units. In addition, it was evidenced that galactans from amaranth seeds are composed of β-(1→4)-linked d-galactopyranose units, which can also be terminated with l-arabinopyranose units. In direct comparison to structural elucidation of amaranth fiber by using methylation analysis, the advantage of the enzymatic approach over methylation analysis was demonstrated. PMID:25529336

  19. In vitro analysis of the effect of alkyl-chain length of anionic surfactants on the skin by using a reconstructed human epidermal model.

    PubMed

    Yamaguchi, Fumiko; Watanabe, Shin-Ichi; Harada, Fusae; Miyake, Miyuki; Yoshida, Masaki; Okano, Tomomichi

    2014-01-01

    We investigated the effect of the alkyl-chain length of anionic surfactants on the skin using an in vitro model. The evaluated anionic surfactants were sodium alkyl sulfate (AS) and sodium fatty acid methyl ester sulfonate (MES), which had different alkyl-chain lengths (C8-C14). Skin tissue damage and permeability were examined using a reconstructed human epidermal model, LabCyte EPI-MODEL24. Skin tissue damage was examined by measuring cytotoxicity with an MTT assay. Liquid chromatography/tandem mass spectrometry (LC/MS-MS) and liquid chromatography/mass spectrometry (LC/MS) were used to detect surfactants that permeated into the assay medium through an epidermal model. To assess the permeation mechanism and cell damage caused by the surfactants through the epidermis, we evaluated the structural changes of Bovine Serum Albumin (BSA), used as a simple model protein, and the fluidity of 1,2-dipalmitoyl-sn-glycero-3-phosphpcholine (DPPC) liposome, which serves as one of the most abundant phospholipid models of living cell membranes in the epidermis. The effects of the surfactants on the proteins were measured using Circular Dichroism (CD) spectroscopy, while the effects on membrane fluidity were investigated by electron spin resonance (ESR) spectroscopy. ET50 (the 50% median effective time) increased as follows: C10 < C12 < C8 < C14 in AS and C8, C10 < C12 < C14 in MES. The order of permeation through the LabCyte EPI-MODEL24 was C10 > C12 > C14, for both AS and MES. For both AS and MES, the order parameter, which is the criteria for the microscopic viscosity of lipid bilayers, increased as follows: C10 < C12 < C14, which means the membrane fluidity is C10 > C12 > C14. It was determined that the difference in skin tissue damage in the LabCyte EPI-MODEL24 with C10 to C14 AS and MES was caused by the difference in permeation and cell membrane fluidity through the lipid bilayer path in the epidermis.

  20. Sulfate-ion-assisted galvanic replacement tuning of silver dendrites to highly branched chains for effective SERS.

    PubMed

    Zhang, Yunxia; Sun, Shaodong; Zhang, Xiaozhe; Tang, Linli; Song, Xiaoping; Yang, Zhimao

    2014-09-21

    Morphology is a primary part of designing metal nanocrystals and nanomaterials with controlled functional properties. Here, we demonstrate the potential of foreign sulfate ions to tune the silver dendrites to highly branched chains through a simple galvanic replacement reaction without introducing any organic surfactants. We further illustrate the underlying mechanism according to diffusion-limited aggregation (DLA) in the presence of sulfate ions. The special aspects of this simple synthetic strategy are the control of both the nucleation process and the subsequent crystal growth stage by using sulfate ions as the ionic surfactants thereby tuning the total surface energies on various crystal facets in solution and transforming crystal growth habits of the products. Moreover, the highly branched silver chains (HBSCs) with pure surfaces have been successfully employed as a Raman probe for surface-enhanced Raman spectroscopic analysis of rhodamine 6G (R6G). The particular morphology of those HBSCs also makes them find potential applications in biosensing, catalysis and optics. PMID:25084025

  1. Branched-chain amino acid supplementation during a 100-km ultra-marathon--a randomized controlled trial.

    PubMed

    Knechtle, Beat; Mrazek, Claudia; Wirth, Andrea; Knechtle, Patrizia; Rüst, Christoph Alexander; Senn, Oliver; Rosemann, Thomas; Imoberdorf, Reinhard; Ballmer, Peter

    2012-01-01

    Ultra-marathon running is supposed to increase the parameters of skeletal muscle damage and impair renal function. The purpose of this study was to investigate the effect of branched-chain amino acid supplementation on skeletal muscle damage and renal function during a 100-km ultra-marathon. Twenty-eight athletes were randomly divided into two groups, one group using branched-chain amino acid supplementation (BCAA) and a control group (CON). The athletes in the BCAA group were supplemented with a total of 50 g of an amino acid concentrate including 20 g of BCAA. The intake of energy, antioxidants and parameters of both skeletal muscle damage and renal function were determined. Race time was not different between BCAA and CON when controlled for the personal best time in a 100-km ultra-marathon. Neither the intake of energy and antioxidants nor the parameters of skeletal muscle damage and renal function were different between BCAA and CON. We concluded that BCAA-supplementation before and during a 100-km ultra-marathon had no effect on performance, skeletal muscle damage or renal function. PMID:23007065

  2. Branched-chain amino acid supplementation during a 100-km ultra-marathon--a randomized controlled trial.

    PubMed

    Knechtle, Beat; Mrazek, Claudia; Wirth, Andrea; Knechtle, Patrizia; Rüst, Christoph Alexander; Senn, Oliver; Rosemann, Thomas; Imoberdorf, Reinhard; Ballmer, Peter

    2012-01-01

    Ultra-marathon running is supposed to increase the parameters of skeletal muscle damage and impair renal function. The purpose of this study was to investigate the effect of branched-chain amino acid supplementation on skeletal muscle damage and renal function during a 100-km ultra-marathon. Twenty-eight athletes were randomly divided into two groups, one group using branched-chain amino acid supplementation (BCAA) and a control group (CON). The athletes in the BCAA group were supplemented with a total of 50 g of an amino acid concentrate including 20 g of BCAA. The intake of energy, antioxidants and parameters of both skeletal muscle damage and renal function were determined. Race time was not different between BCAA and CON when controlled for the personal best time in a 100-km ultra-marathon. Neither the intake of energy and antioxidants nor the parameters of skeletal muscle damage and renal function were different between BCAA and CON. We concluded that BCAA-supplementation before and during a 100-km ultra-marathon had no effect on performance, skeletal muscle damage or renal function.

  3. The Impact of the Branched-Chain Ketoacid Dehydrogenase Complex on Amino Acid Homeostasis in Arabidopsis1[OPEN

    PubMed Central

    Peng, Cheng; Uygun, Sahra; Shiu, Shin-Han; Last, Robert L.

    2015-01-01

    The branched-chain amino acids (BCAAs) Leu, Ile, and Val are among nine essential amino acids that must be obtained from the diet of humans and other animals, and can be nutritionally limiting in plant foods. Despite genetic evidence of its importance in regulating seed amino acid levels, the full BCAA catabolic network is not completely understood in plants, and limited information is available regarding its regulation. In this study, transcript coexpression analyses revealed positive correlations among BCAA catabolism genes in stress, development, diurnal/circadian, and light data sets. A core subset of BCAA catabolism genes, including those encoding putative branched-chain ketoacid dehydrogenase subunits, is highly expressed during the night in plants on a diel cycle and in prolonged darkness. Mutants defective in these subunits accumulate higher levels of BCAAs in mature seeds, providing genetic evidence for their function in BCAA catabolism. In addition, prolonged dark treatment caused the mutants to undergo senescence early and overaccumulate leaf BCAAs. These results extend the previous evidence that BCAAs can be catabolized and serve as respiratory substrates at multiple steps. Moreover, comparison of amino acid profiles between mature seeds and dark-treated leaves revealed differences in amino acid accumulation when BCAA catabolism is perturbed. Together, these results demonstrate the consequences of blocking BCAA catabolism during both normal growth conditions and under energy-limited conditions. PMID:25986129

  4. Age and nutrition influence the concentrations of three branched chain fatty acids in sheep fat from Australian abattoirs.

    PubMed

    Watkins, P J; Rose, G; Salvatore, L; Allen, D; Tucman, D; Warner, R D; Dunshea, F R; Pethick, D W

    2010-11-01

    The characteristic mutton odour, associated with the cooked meat of older sheep, can be problematic for some consumers who find the odour disagreeable. Branch chain fatty acids (BCFAs) are considered to be the main determinants of mutton odour. In this study, the aim was to identify the factors influencing the BCFA content of animals at abattoirs in Australia. Samples of subcutaneous fat from over the chump (gluteus medius) were collected from 533 sheep carcasses at abattoirs in New South Wales, Victoria and Western Australia. The carcasses were from sheep differing in age, gender, breed and nutrition. The concentrations of three branched chain fatty acids (BCFAs); namely, 4-methyloctanoic (MOA), 4-ethyloctanoic (EOA) and 4-methylnonanoic acids (MNA), were determined. Statistical modelling showed that, with pre-slaughter nutrition in the model as a random term, BCFA concentrations could be used for discriminating the age of sheep. Fat samples from lamb carcasses had lower MOA and EOA concentrations and a higher concentration of MNA in comparison to hogget and mutton (P<0.05). When nutrition was excluded as a random effect from the statistical model, the MOA and MNA concentrations did not differentiate between lamb, hogget and mutton whereas, for EOA, lamb had a lower concentration than mutton (P<0.05) with hogget intermediate. An interaction existed between age and gender (P<0.05) where female lambs had lower EOA concentrations relative to the mutton but not for castrates.

  5. The regulation of branched-chain 2-oxo acid dehydrogenase of liver, kidney and heart by phosphorylation.

    PubMed Central

    Hughes, W A; Halestrap, A P

    1981-01-01

    1. Incubation of mitochondria from heart, liver and kidney with [32P]phosphate allowed 32P incorporation into two intramitochondrial proteins, the decarboxylase alpha-subunit of the pyruvate dehydrogenase complex (mol.wt 42000) and a protein of mol.wt. 48000. 2. This latter protein incorporated 32P more slowly than did pyruvate dehydrogenase, was not precipitated by antibody to pyruvate dehydrogenase and showed behaviour distinct from that of pyruvate dehydrogenase towards high-speed centrifugation and pyruvate dehydrogenase phosphate phosphatase. 3. 32P incorporation into the protein was greatly diminished by the presence of 0.1 mM-4-methyl-2-oxopentanoate, but enhanced by pyruvate (1 mM), hypo-osmotic treatment of mitochondria and, under some conditions, by uncoupler. 4. The activity of branched-chain 2-oxo acid dehydrogenase was assayed in parallel experiments. Under appropriate conditions the enzyme was inhibited when 32P incorporation was increased and activated when incorporation was decreased. The data suggest that the 48000-mol.wt. phosphorylated protein is identical with the decarboxylase subunit of branched-chain 2-oxo acid dehydrogenase and that this enzyme may be controlled by a phosphorylation-dephosphorylation cycle akin to that for pyruvate dehydrogenase. 5. Strict correlation between activity and 32P incorporation was not observed, and a scheme for the regulation of the enzyme is proposed to account for these discrepancies. PMID:7316988

  6. Effect of side-chain asymmetry on the intermolecular structure and order-disorder transition in alkyl-substituted polyfluorenes

    NASA Astrophysics Data System (ADS)

    Knaapila, M.; Stepanyan, R.; Torkkeli, M.; Haase, D.; Fröhlich, N.; Helfer, A.; Forster, M.; Scherf, U.

    2016-04-01

    We study relations among the side-chain asymmetry, structure, and order-disorder transition (ODT) in hairy-rod-type poly(9,9-dihexylfluorene) (PF6) with two identical side chains and atactic poly(9-octyl-9-methyl-fluorene) (PF1-8) with two different side chains per repeat. PF6 and PF1-8 organize into alternating side-chain and backbone layers that transform into an isotropic phase at TODT(PF 6 ) and TbiODT(PF 1 -8 ) . We interpret polymers in terms of monodisperse and bidisperse brushes and predict scenarios TODTchain length above or below the average grafting distance). Calorimetry and x-ray scattering indicate the condition TODT(PF 6 ) ˜TbiODT(PF 1 -8 ) following the low grafting prediction. PF6 side chains coming from the alternating backbone layers appear as two separate layers with thickness H (PF 6 ) , whereas PF1-8 side chains appear as an indistinguishable bilayer with a half thickness Hbilayer(PF 1 -8 ) /2 ≈H (PF 6 ) . The low grafting density region is structurally possible but not certain for PF6 and confirmed for PF1-8.

  7. STUDIES ON THE METABOLIC FUNCTION OF BRANCHED-CHAIN VOLATILE FATTY ACIDS, GROWTH FACTORS FOR RUMINOCOCCI I.

    PubMed Central

    Allison, Milton J.; Bryant, Marvin P.; Doetsch, Raymond N.

    1962-01-01

    Allison, Milton J. (Dairy Cattle Research Branch, U. S. Department of Agriculture, Beltsville, Md.), M. P. Bryant, and R. N. Doetsch. Studies on the metabolic function of branched-chain volatile fatty acids, growth factors for ruminococci. I. Incorporation of isovalerate into leucine. J. Bacteriol. 83:523–532. 1962.—Ruminococcus flavefaciens strain C94, a cellulolytic rumen bacterium, requires either isobutyrate or isovalerate for growth. The organism was grown in the presence of C14-labeled isovalerate, and the metabolic fate of the labeled carbon was studied to obtain information on the functions of this growth factor. Radioactivity from isovalerate-1-C14 and isovalerate-3-C14 was found mainly in the protein and lipid fractions of the cells. The C14 in protein was all in leucine, indicating that a function of isovalerate was to serve as a carbon skeleton for leucine synthesis. As C14 in leucine synthesized from isovalerate-1-C14 was entirely in carbon 2, the intact isovalerate molecule was apparently incorporated into leucine. This is evidence that leucine was synthesized by a mechanism different from that previously demonstrated in other microorganisms. R. flavefaciens has a definite but limited ability to incorporate exogenous amino acids, including leucine. It incorporated 2% of the C14 during growth in uniformly labeled (UL) C14-Chlorella protein hydrolyzate; Escherichia coli incorporated 37% of the label under similar conditions. In another experiment, a limited amount of exogenous leucine-2-C14 was incorporated into protein of R. flavefaciens. The requirement for isovalerate was not replaced by dl-leucine or 2-ketoisocaproate. It is suggested that isovalerate or isobutyrate is required because R. flavefaciens has a limited ability to incorporate exogenous branched-chain amino acids and a limited ability to synthesize the isopropyl group found in these amino acids and in other components of the cell. Images PMID:13860621

  8. Surface energy of silicas, grafted with alkyl chains of increasing lengths, as measured by contact angle techniques

    SciTech Connect

    Kessaissia, Z. Papirer, E.; Donnet, J.B.

    1981-08-01

    Silica, modified by esterification with linear alcohols having between 1 and 20 carbon atoms, is compacted into smooth discs. Their surface polarity, measured by contact angle techniques, decreases with increasing surface coverage and chain length of the grafts. For the longer chains, the surface energy of the grafted silicas reaches a value close to the one of poly(ethylene). The spreading pressures of water on the modified silicas were measured either by contact angle or vapor adsorption techniques. 13 references.

  9. Weight gain in anorexia nervosa does not ameliorate the faecal microbiota, branched chain fatty acid profiles, and gastrointestinal complaints

    PubMed Central

    Mack, Isabelle; Cuntz, Ulrich; Grämer, Claudia; Niedermaier, Sabrina; Pohl, Charlotte; Schwiertz, Andreas; Zimmermann, Kurt; Zipfel, Stephan; Enck, Paul; Penders, John

    2016-01-01

    The gut microbiota not only influences host metabolism but can also affect brain function and behaviour through the microbiota-gut-brain axis. To explore the potential role of the intestinal microbiota in anorexia nervosa (AN), we comprehensively investigated the faecal microbiota and short-chain fatty acids in these patients before (n = 55) and after weight gain (n = 44) in comparison to normal-weight participants (NW, n = 55) along with dietary intake and gastrointestinal complaints. We show profound microbial perturbations in AN patients as compared to NW participants, with higher levels of mucin-degraders and members of Clostridium clusters I, XI and XVIII and reduced levels of the butyrate-producing Roseburia spp. Branched-chain fatty acid concentrations, being markers for protein fermentation, were elevated. Distinct perturbations in microbial community compositions were observed for individual restrictive and binge/purging AN-subtypes. Upon weight gain, microbial richness increased, however perturbations in intestinal microbiota and short chain fatty acid profiles in addition to several gastrointestinal symptoms did not recover. These insights provide new leads to modulate the intestinal microbiota in order to improve the outcomes of the standard therapy. PMID:27229737

  10. Cross-talk between branched-chain amino acids and hepatic mitochondria is compromised in nonalcoholic fatty liver disease.

    PubMed

    Sunny, Nishanth E; Kalavalapalli, Srilaxmi; Bril, Fernando; Garrett, Timothy J; Nautiyal, Manisha; Mathew, Justin T; Williams, Caroline M; Cusi, Kenneth

    2015-08-15

    Elevated plasma branched-chain amino acids (BCAA) in the setting of insulin resistance have been relevant in predicting type 2 diabetes mellitus (T2DM) onset, but their role in the etiology of hepatic insulin resistance remains uncertain. We determined the link between BCAA and dysfunctional hepatic tricarboxylic acid (TCA) cycle, which is a central feature of hepatic insulin resistance and nonalcoholic fatty liver disease (NAFLD). Plasma metabolites under basal fasting and euglycemic hyperinsulinemic clamps (insulin stimulation) were measured in 94 human subjects with varying degrees of insulin sensitivity to identify their relationships with insulin resistance. Furthermore, the impact of elevated BCAA on hepatic TCA cycle was determined in a diet-induced mouse model of NAFLD, utilizing targeted metabolomics and nuclear magnetic resonance (NMR)-based metabolic flux analysis. Insulin stimulation revealed robust relationships between human plasma BCAA and indices of insulin resistance, indicating chronic metabolic overload from BCAA. Human plasma BCAA and long-chain acylcarnitines also showed a positive correlation, suggesting modulation of mitochondrial metabolism by BCAA. Concurrently, mice with NAFLD failed to optimally induce hepatic mTORC1, plasma ketones, and hepatic long-chain acylcarnitines, following acute elevation of plasma BCAA. Furthermore, elevated BCAA failed to induce multiple fluxes through hepatic TCA cycle in mice with NAFLD. Our data suggest that BCAA are essential to mediate efficient channeling of carbon substrates for oxidation through mitochondrial TCA cycle. Impairment of BCAA-mediated upregulation of the TCA cycle could be a significant contributor to mitochondrial dysfunction in NAFLD. PMID:26058864

  11. Metabolism of branched-chain amino acids and ammonia during exercise: clues from McArdle's disease.

    PubMed

    Wagenmakers, A J; Coakley, J H; Edwards, R H

    1990-05-01

    Patients with McArdle's disease (myophosphorylase deficiency) cannot use muscle glycogen as an energy source during exercise. They therefore are an ideal model to learn about the metabolic adaptations which develop during endurance exercise leading to glycogen depletion. This review summarizes the current knowledge of ammonia and amino acid metabolism in these patients and also adds several new data. During incremental exercise tests in patients with McArdle's disease, forearm venous plasma ammonia concentration rises to a value between 200 and 500 microM. Femoral arteriovenous difference studies show that muscle produces the ammonia. The leg release of both ammonia and glutamine (in mumol/min) has been estimated to be five- to tenfold larger in one of these patients than in healthy individuals exercising at comparable relative work load. Patients with McArdle's disease have a larger uptake of branched-chain amino acids (BCAA) by exercising leg muscles and show a more rapid activation of the muscle branched-chain 2-oxo acid dehydrogenase complex, a key enzyme in the degradation of the BCAA. In general, supplements of BCAA taken before the exercise test lead to a deterioration of exercise performance and a higher increase in heart rate and plasma ammonia during exercise, whereas supplements of branched-chain 2-oxo acids improve exercise performance and lead to a smaller increase in heart rate and plasma ammonia. At constant power output, patients with McArdle's disease show a rapid increase in heart rate and exertion perceived in the exercising muscles, which peak within 10 min after the start of exercise and then fall again ("second wind"). Peak heart rate and peak exertion coincide with a peak in plasma ammonia. Ammonia production during exercise in these patients is estimated to exceed the reported breakdown of ATP to IMP and therefore most likely originates from the metabolism of amino acids. Deamination of amino acids via the reactions of the purine nucleotide

  12. New cyclotetrasiloxanes bearing sila-alkyl substituted side chains and their applications as templates for gold nanowires.

    PubMed

    Shankar, Ravi; Chaudhary, Manchal; Molloy, Kieran C; Kociok-Köhn, Gabriele

    2013-06-01

    New sila-alkyl substituted cyclotetrasiloxanes, [RMe2SiCH2CH2(Me)SiO]4 [R = Ph(1), 2-thienyl(2), 2-furyl(3)] have been synthesized by a hydrosilylation reaction between 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, (D4(Vi)) and dimethylphenylsilane/dimethyl-2-thienylsilane/dimethyl-2-furylsilane in the presence of Karstedt's catalyst. X-ray crystallographic studies of 1 and 2 reveal all-trans conformation of the methyl groups bonded to puckered siloxane core and formation of 3D supramolecular assemblies by virtue of intermolecular C-H···π interactions. These siloxanes act as potential templates for expeditious one pot synthesis of gold nanowires of varying aspect ratios which are obtained by reduction of HAuCl4·3H2O with triethylsilane (CHCl3, RT). On the other hand, the use of linear polysiloxane, [2-ThMe2SiCH2CH2(Me)SiO]n (4) in lieu of the cyclosiloxane 2 affords predominant formation of polydispersed AuNPs along with a few extended structures. These results suggest that conformational confinement of the appended groups on the cyclosiloxanes, 1-3 plays an important role to impart morphological control of the gold nanowire assemblies.

  13. High Efficiency Antimicrobial Thiazolium and Triazolium Side-Chain Polymethacrylates Obtained by Controlled Alkylation of the Corresponding Azole Derivatives.

    PubMed

    Tejero, Rubén; López, Daniel; López-Fabal, Fátima; Gómez-Garcés, José L; Fernández-García, Marta

    2015-06-01

    Two series of antimicrobial polymethacrylates (PMTAs) bearing mono and bis-cationic quaternary ammonium cations (QUATs) were prepared by controlled N-alkylation of 1,3-thiazole and 1,2,3-triazole pendant groups with butyl iodide (PMTAs-BuI). The degree of quaternization (DQ) of the azole heterocycles was monitored by (1)H NMR spectroscopy over a wide range of reaction times. Spectra analysis of the (1)H NMR aromatic region allowed to characterize and quantify the different species involved and, therefore, to control the chemical composition distribution of the amphiphilic polycations. The polymer charge density and the hydrodynamic sizes were measured by zeta potential and dynamic light scattering (DLS), respectively. Consequently, the relationship between structure and antibacterial properties and toxicity was studied. Interestingly, these polyelectrolytes present excellent selective toxicity against bacteria being nonhemolytic even at low values of DQ. Furthermore, they were also evaluated for their microbial time-killing efficiency, presenting a 3 log-reduction in only 15 min. Additionally, the bacteria cell morphology treated with PMTAs-BuI was analyzed. PMID:25944495

  14. Novel indolin-2-one-substituted methanofullerenes bearing long n-alkyl chains: synthesis and application in bulk-heterojunction solar cells

    PubMed Central

    Romanova, Irina P; Izdelieva, Inessa A; Trukhanov, Vasily A; Shaikhutdinova, Gulnara R; Yakhvarov, Dmitry G; Latypov, Shamil K; Mironov, Vladimir F; Dyakov, Vladimir A; Golovnin, Ilya V; Paraschuk, Dmitry Yu; Sinyashin, Oleg G

    2014-01-01

    Summary An easy, high-yield and atom-economic procedure of a C60 fullerene modification using a reaction of fullerene C60 with N-alkylisatins in the presence of tris(diethylamino)phosphine to form novel long-chain alkylindolinone-substituted methanofullerenes (AIMs) is described. Optical absorption, electrochemical properties and solubility of AIMs were studied. Poly(3-hexylthiophene-2,5-diyl) (P3HT)/AIMs solar cells were fabricated and the effect of the AIM alkyl chain length and the P3HT:AIM ratio on the solar cell performance was studied. The power conversion efficiencies of about 2% were measured in the P3HT/AIM devices with 1:0.4 P3HT:AIM weight ratio for the AIMs with hexadecyl and dodecyl substituents. From the optical and AFM data, we suggested that the AIMs, in contrast to [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), do not disturb the P3HT crystalline domains. Moreover, the more soluble AIMs do not show a better miscibility with the P3HT crystalline phase. PMID:24991262

  15. The peroxisomal Acyl-CoA thioesterase Pte1p from Saccharomyces cerevisiae is required for efficient degradation of short straight chain and branched chain fatty acids.

    PubMed

    Maeda, Isamu; Delessert, Syndie; Hasegawa, Seiko; Seto, Yoshiaki; Zuber, Sophie; Poirier, Yves

    2006-04-28

    The role of the Saccharomyces cerevisae peroxisomal acyl-coenzyme A (acyl-CoA) thioesterase (Pte1p) in fatty acid beta-oxidation was studied by analyzing the in vitro kinetic activity of the purified protein as well as by measuring the carbon flux through the beta-oxidation cycle in vivo using the synthesis of peroxisomal polyhydroxyalkanoate (PHA) from the polymerization of the 3-hydroxyacyl-CoAs as a marker. The amount of PHA synthesized from the degradation of 10-cis-heptadecenoic, tridecanoic, undecanoic, or nonanoic acids was equivalent or slightly reduced in the pte1Delta strain compared with wild type. In contrast, a strong reduction in PHA synthesized from heptanoic acid and 8-methyl-nonanoic acid was observed for the pte1Delta strain compared with wild type. The poor catabolism of 8-methyl-nonanoic acid via beta-oxidation in pte1Delta negatively impacted the degradation of 10-cis-heptadecenoic acid and reduced the ability of the cells to efficiently grow in medium containing such fatty acids. An increase in the proportion of the short chain 3-hydroxyacid monomers was observed in PHA synthesized in pte1Delta cells grown on a variety of fatty acids, indicating a reduction in the metabolism of short chain acyl-CoAs in these cells. A purified histidine-tagged Pte1p showed high activity toward short and medium chain length acyl-CoAs, including butyryl-CoA, decanoyl-CoA and 8-methyl-nonanoyl-CoA. The kinetic parameters measured for the purified Pte1p fit well with the implication of this enzyme in the efficient metabolism of short straight and branched chain fatty acyl-CoAs by the beta-oxidation cycle.

  16. Vibrational density of states of triphenylene based discotic liquid crystals: dependence on the length of the alkyl chain.

    PubMed

    Krause, Christina; Zorn, Reiner; Emmerling, Franziska; Falkenhagen, Jana; Frick, Bernhard; Huber, Patrick; Schönhals, Andreas

    2014-04-28

    The vibrational density of states of a series of homologous triphenylene-based discotic liquid crystals HATn (n = 5, 6, 8, 10, 12) depending on the length of the aliphatic side chain is investigated by means of inelastic neutron scattering. All studied materials have a plastic crystalline phase at low temperatures, followed by a hexagonally ordered liquid crystalline phase at higher temperatures and a quasi isotropic phase at the highest temperatures. The X-ray scattering pattern for the plastic crystalline phase of all materials shows a sharp Bragg reflection corresponding to the intercolumnar distance in the lower q-range and a peak at circa 17 nm(-1) related to intracolumnar distances between the cores perpendicular to the columns as well as a broad amorphous halo related to the disordered structure of the methylene groups in the side chains in the higher q-range. The intercolumnar distance increases linearly with increasing chain length for the hexagonal columnar ordered liquid crystalline phase. A similar behaviour is assumed for the plastic crystalline phase. Besides n = 8 all materials under study exhibit a Boson peak. With increasing chain length, the frequency of the Boson peak decreases and its intensity increases. This can be explained by a self-organized confinement model. The peaks for n = 10, 12 are much narrower than for n = 5, 6 which might imply the transformation from a rigid system to a softer one with increasing chain length. Moreover the results can also be discussed in the framework of a transition from an uncorrelated to a correlated disorder with increasing n where n = 8 might be speculatively considered as a transitional state.

  17. Influence of alkyl chain length on charge transport in symmetrically substituted poly(2,5-dialkoxy- p -phenylenevinylene) polymers

    NASA Astrophysics Data System (ADS)

    Tuladhar, Sachetan M.; Sims, Marc; Kirkpatrick, James; Maher, Robert C.; Chatten, Amanda J.; Bradley, Donal D. C.; Nelson, Jenny; Etchegoin, Pablo G.; Nielsen, Christian B.; Massiot, Philippe; George, Wayne N.; Steinke, Joachim H. G.

    2009-01-01

    We report on the hole transport characteristics, as measured by time of flight, of a family of symmetrically substituted dialkoxy poly( p -phenylenevinylene) polymers with different side-chain length. As side-chain length is decreased, the magnitude of the hole mobility μh increases while the field dependence of μh becomes more positive and the temperature dependence of μh becomes stronger. For the shortest side-chain derivative studied, μh exceeds 10-4cm2V-1s-1 at electric fields greater than 105Vcm-1 . The trend in magnitude of μh with side-chain length is consistent with the expected increase in electronic wave-function overlap as interchain separation decreases, while the trends in electric-field and temperature dependences of μh are consistent with increasing site energy disorder. We show that the electrostatic contribution to the site energy difference for pairs of oligomers follows the observed trend as a function of interchain separation, although the pairwise contribution is too small to explain the data quantitatively. Nonresonant Raman spectroscopy is used to characterize the microstructure of our films. We construct spatial maps of the Raman ratio I1280/I1581 and confirm an expected decrease in average film density with side-chain extension. The structural heterogeneity in the maps is analyzed but no clear correlation is observed with transport properties, suggesting that the structural variations relevant for charge transport occur on a length scale finer than the resolution of ˜1μm .

  18. Structure and biosynthesis of the marine streptomycete ansamycin ansalactam A and its distinctive branched chain polyketide extender unit.

    PubMed

    Wilson, Micheal C; Nam, Sang-Jip; Gulder, Tobias A M; Kauffman, Christopher A; Jensen, Paul R; Fenical, William; Moore, Bradley S

    2011-02-16

    Reported is the structure and biosynthesis of ansalactam A, an ansamycin class polyketide produced by an unusual modification of the polyketide pathway. This new metabolite, produced by a marine sediment-derived bacterium of the genus Streptomyces , possesses a novel spiro γ-lactam moiety and a distinctive isobutyryl polyketide fragment observed for the first time in this class of natural products. The structure of ansalactam A was defined by spectroscopic methods including X-ray crystallographic analysis. Biosynthetic studies with stable isotopes further led to the discovery of a new, branched chain polyketide synthase extender unit derived from (E)-4-methyl-2-pentenoic acid for polyketide assembly observed for the first time in this class of natural products.

  19. Facile synthesis of thiol-functionalized long-chain highly branched ROMP polymers and surface-decorated with gold nanoparticles.

    PubMed

    Ding, Liang; Qiu, Jun; Zhu, Zhenshu

    2013-10-01

    The synthesis of thiol-functionalized long-chain highly branched polymers (LCHBPs) has been accomplished in combination of ring-opening metathesis polymerization (ROMP) and thiol-Michael addition click reaction. A monotelechelic polymer with a terminal acrylate and many pendent thiol groups is first prepared through adding an internal cis-olefin terminating agent to the reaction mixture immediately after the completion of the living ROMP, and then utilized as an ABn -type macromonomer in subsequent thiol-ene reaction between acrylate and thiol, yielding LCHBPs as the reaction time prolonged. Au nanoparticles are then covalently conjugated onto the surface of thiol-functionalized LCHBP to fabricate novel hybrid nanostructures, which is shown as one interesting application of such functionalized metathesis polymers. This facile approach can be extended toward the fabrication of novel nanomaterials with sophisticated structures and tunable multifunctionalities.

  20. [Alterations in the excess synthesis of riboflavin in Pichia guilliermondii under the influence of branched-chain amino acids].

    PubMed

    Shlee, D

    1977-01-01

    The effect of the branched-chain amino acids: L-valine, L-isoleucine and L-leucine on riboflavin overproduction was studied in the Pichia (Candida) guilliermondii (Cast.) Lang. et G. yeast, L-Val, L-Ile and L-Leu were found to inhibit riboflavin overproduction only under iron-deficient growth conditions. Other amino acids used did not show this effect. In crude extracts of P. guilliermondii the specific activity of the alpha-acetolactate forming enzyme, pH 8.0, is inhibited by L-Val. It is revealed that the activity of alpha-acetolactate synthetase in iron-deficient riboflavin-overproduction cells was exceedingly higher than in the valine-inhibited cells. Under iron deficiency alpha-acetolactate synthetase shows maximal activity after 48 h of growth. It was possible to detect diacetyl (and aceton) in the culture fluid. PMID:867527

  1. Formally direct pathways and low-temperature chain branching in hydrocarbon autoignition : the cyclohexyl + O2 reaction at high pressure.

    SciTech Connect

    Taatjes, Craig A.; Jusinski, Leonard E.; Zador, Judit; Fernandes, Ravi X.; Miller, James A.

    2008-10-01

    The OH concentration in the Cl-initiated oxidation of cyclohexane has been measured between 6.5-20.3 bar and in the 586-828 K temperature range by a pulsed-laser photolytic initiation--laser-induced fluorescence method. The experimental OH profiles are modeled by using a master-equation-based kinetic model as well as a comprehensive literature mechanism. Below 700 K OH formation takes place on two distinct time-scales, one on the order of microseconds and the other over milliseconds. Detailed modeling demonstrates that formally direct chemical activation pathways are responsible for the OH formation on short timescales. These results establish that formally direct pathways are surprisingly important even for relatively large molecules at the pressures of practical combustors. It is also shown that remaining discrepancies between model and experiment are attributable to low-temperature chain branching from the addition of the second oxygen to hydroperoxycyclohexyl radicals.

  2. Does Branched-Chain Amino Acids Supplementation Modulate Skeletal Muscle Remodeling through Inflammation Modulation? Possible Mechanisms of Action

    PubMed Central

    Nicastro, Humberto; da Luz, Claudia Ribeiro; Chaves, Daniela Fojo Seixas; Bechara, Luiz Roberto Grassmann; Voltarelli, Vanessa Azevedo; Rogero, Marcelo Macedo; Lancha, Antonio Herbert

    2012-01-01

    Skeletal muscle protein turnover is modulated by intracellular signaling pathways involved in protein synthesis, degradation, and inflammation. The proinflammatory status of muscle cells, observed in pathological conditions such as cancer, aging, and sepsis, can directly modulate protein translation initiation and muscle proteolysis, contributing to negative protein turnover. In this context, branched-chain amino acids (BCAAs), especially leucine, have been described as a strong nutritional stimulus able to enhance protein translation initiation and attenuate proteolysis. Furthermore, under inflammatory conditions, BCAA can be transaminated to glutamate in order to increase glutamine synthesis, which is a substrate highly consumed by inflammatory cells such as macrophages. The present paper describes the role of inflammation on muscle remodeling and the possible metabolic and cellular effects of BCAA supplementation in the modulation of inflammatory status of skeletal muscle and the consequences on protein synthesis and degradation. PMID:22536489

  3. Coadministration of branched-chain amino acids and lipopolysaccharide causes matrix metalloproteinase activation and blood-brain barrier breakdown.

    PubMed

    Scaini, Giselli; Morais, Meline O S; Galant, Leticia S; Vuolo, Francieli; Dall'Igna, Dhébora M; Pasquali, Matheus A B; Ramos, Vitor M; Gelain, Daniel P; Moreira, Jose Claudio F; Schuck, Patrícia F; Ferreira, Gustavo C; Soriano, Francisco G; Dal-Pizzol, Felipe; Streck, Emilio L

    2014-10-01

    Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by a severe deficiency in the activity of the branched-chain α-keto acid dehydrogenase complex, leading to accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine, and valine. Infections have a significant role in precipitating acute metabolic decompensation in patients with MSUD; however, the mechanisms underlying the neurotoxicity in this disorder are poorly understood. In this study, we subjected rats to the coadministration of lipopolysaccharide (LPS), which is a major component of gram-negative bacteria cell walls, and high concentrations of BCAA (H-BCAA) to determine their effects on the permeability of the blood-brain barrier (BBB) and on the levels of matrix metalloproteinases (MMP-2 and MMP-9). Our results demonstrated that the coadministration of H-BCAA and LPS causes breakdown of the BBB and increases the levels of MMP-2 and MMP-9 in the hippocampus of these rats. On the other hand, examination of the cerebral cortex of the 10- and 30-day-old rats revealed a significant difference in Evan's Blue content after coadministration of H-BCAA and LPS, as MMP-9 levels only increased in the cerebral cortex of the 10-day-old rats. In conclusion, these results suggest that the inflammatory process associated with high levels of BCAA causes BBB breakdown. Thus, we suggest that BBB breakdown is relevant to the perpetuation of brain inflammation and may be related to the brain dysfunction observed in MSUD patients. PMID:24390570

  4. Acute Administration of Branched-Chain Amino Acids Increases the Pro-BDNF/Total-BDNF Ratio in the Rat Brain.

    PubMed

    Scaini, Giselli; Morais, Meline O S; Furlanetto, Camila B; Kist, Luiza W; Pereira, Talita C B; Schuck, Patrícia F; Ferreira, Gustavo C; Pasquali, Matheus A B; Gelain, Daniel P; Moreira, José Cláudio F; Bogo, Maurício R; Streck, Emilio L

    2015-05-01

    Maple syrup urine disease (MSUD) is caused by an inborn error in metabolism resulting from a deficiency in the branched-chain α-keto acid dehydrogenase complex activity. This blockage leads to accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine and valine, as well as their corresponding α-keto acids and α-hydroxy acids. High levels of BCAAs are associated with neurological dysfunction and the role of pro- and mature brain-derived neurotrophic factor (BDNF) in the neurological dysfunction of MSUD is still unclear. Thus, in the present study we investigated the effect of an acute BCAA pool administration on BDNF levels and on the pro-BDNF cleavage-related proteins S100A10 and tissue plasminogen activator (tPA) in rat brains. Our results demonstrated that acute Hyper-BCAA (H-BCAA) exposure during the early postnatal period increases pro-BDNF and total-BDNF levels in the hippocampus and striatum. Moreover, tPA levels were significantly decreased, without modifications in the tPA transcript levels in the hippocampus and striatum. On the other hand, the S100A10 mRNA and S100A10 protein levels were not changed in the hippocampus and striatum. In the 30-day-old rats, we observed increased pro-BDNF, total-BDNF and tPA levels only in the striatum, whereas the tPA and S100A10 mRNA expression and the immunocontent of S100A10 were not altered. In conclusion, we demonstrated that acute H-BCAA administration increases the pro-BDNF/total-BDNF ratio and decreases the tPA levels in animals, suggesting that the BCAA effect may depend, at least in part, on changes in BDNF post-translational processing. PMID:25681161

  5. YjeH Is a Novel Exporter of l-Methionine and Branched-Chain Amino Acids in Escherichia coli.

    PubMed

    Liu, Qian; Liang, Yong; Zhang, Yun; Shang, Xiuling; Liu, Shuwen; Wen, Jifu; Wen, Tingyi

    2015-11-01

    Amino acid efflux transport systems have important physiological functions and play vital roles in the fermentative production of amino acids. However, no methionine exporter has yet been identified in Escherichia coli. In this study, we identified a novel amino acid exporter, YjeH, in E. coli. The yjeH overexpression strain exhibited high tolerance to the structural analogues of l-methionine and branched-chain amino acids, decreased intracellular amino acid levels, and enhanced export rates in the presence of a Met-Met, Leu-Leu, Ile-Ile, or Val-Val dipeptide, suggesting that YjeH functions as an exporter of l-methionine and the three branched-chain amino acids. The export of the four amino acids in the yjeH overexpression strain was competitively inhibited in relation to each other. The expression of yjeH was strongly induced by increasing cytoplasmic concentrations of substrate amino acids. Green fluorescent protein (GFP)-tagged YjeH was visualized by total internal reflection fluorescence microscopy to confirm the plasma membrane localization of YjeH. Phylogenetic analysis of transporters indicated that YjeH belongs to the amino acid efflux family of the amino acid/polyamine/organocation (APC) superfamily. Structural modeling revealed that YjeH has the typical "5 + 5" transmembrane α-helical segment (TMS) inverted-repeat fold of APC superfamily transporters, and its binding sites are strictly conserved. The enhanced capacity of l-methionine export by the overexpression of yjeH in an l-methionine-producing strain resulted in a 70% improvement in titer. This study supplements the transporter classification and provides a substantial basis for the application of the methionine exporter in metabolic engineering.

  6. Growth-Environment Dependent Modulation of Staphylococcus aureus Branched-Chain to Straight-Chain Fatty Acid Ratio and Incorporation of Unsaturated Fatty Acids

    PubMed Central

    Sen, Suranjana; Sirobhushanam, Sirisha; Johnson, Seth R.; Song, Yang; Tefft, Ryan; Gatto, Craig; Wilkinson, Brian J.

    2016-01-01

    The fatty acid composition of membrane glycerolipids is a major determinant of Staphylococcus aureus membrane biophysical properties that impacts key factors in cell physiology including susceptibility to membrane active antimicrobials, pathogenesis, and response to environmental stress. The fatty acids of S. aureus are considered to be a mixture of branched-chain fatty acids (BCFAs), which increase membrane fluidity, and straight-chain fatty acids (SCFAs) that decrease it. The balance of BCFAs and SCFAs in USA300 strain JE2 and strain SH1000 was affected considerably by differences in the conventional laboratory medium in which the strains were grown with media such as Mueller-Hinton broth and Luria broth resulting in high BCFAs and low SCFAs, whereas growth in Tryptic Soy Broth and Brain-Heart Infusion broth led to reduction in BCFAs and an increase in SCFAs. Straight-chain unsaturated fatty acids (SCUFAs) were not detected. However, when S. aureus was grown ex vivo in serum, the fatty acid composition was radically different with SCUFAs, which increase membrane fluidity, making up a substantial proportion of the total (<25%) with SCFAs (>37%) and BCFAs (>36%) making up the rest. Staphyloxanthin, an additional major membrane lipid component unique to S. aureus, tended to be greater in content in cells with high BCFAs or SCUFAs. Cells with high staphyloxanthin content had a lower membrane fluidity that was attributed to increased production of staphyloxanthin. S. aureus saves energy and carbon by utilizing host fatty acids for part of its total fatty acids when growing in serum, which may impact biophysical properties and pathogenesis given the role of SCUFAs in virulence. The nutritional environment in which S. aureus is grown in vitro or in vivo in an infection is likely to be a major determinant of membrane fatty acid composition. PMID:27788193

  7. Dendronized Polyimides Bearing Long-Chain Alkyl Groups and Their Application for Vertically Aligned Nematic Liquid Crystal Displays

    PubMed Central

    Tsuda, Yusuke; OH, Jae Min; Kuwahara, Renpei

    2009-01-01

    Polyimides having dendritic side chains were investigated. The terphenylene diamine monomer having a first-generation monodendron, 3,4,5-tris(n-dodecyloxy)-benzoate and the monomer having a second-generation monodendron, 3,4,5-tris[-3’,4’,5’-tri(n-dodecyloxy)benzyloxy]benzoate were successfully synthesized and the corresponding soluble dendritic polyimides were obtained by polycondensation with conventional tetracarboxylic dianhydride monomers such as benzophenone tertracarboxylic dianhydride (BTDA). The two-step polymerizations in NMP that is a general method for the synthesis of soluble polyimides is difficult; however, the expected dendritic polyimides can be obtained in aromatic polar solvents such as m-cresol and pyridine. The solubility of these dendoronized polyimides is characteristic; soluble in common organic solvents such as dichloromethane, chloroform, toluene and THF. These dendronized polyimides exhibited high glass transition temperatures and good thermal stability in both air and under nitrogen. Their application as alignment layers for LCDs was investigated, and it was found that these polyimides having dendritic side chains were applicable for the vertically aligned nematic liquid crystal displays (VAN-LCDs). PMID:20087476

  8. Alkyl polyglucose enhancing propionic acid enriched short-chain fatty acids production during anaerobic treatment of waste activated sludge and mechanisms.

    PubMed

    Luo, Jingyang; Feng, Leiyu; Chen, Yinguang; Sun, Han; Shen, Qiuting; Li, Xiang; Chen, Hong

    2015-04-15

    Adding alkyl polyglucose (APG) into an anaerobic treatment system of waste activated sludge (WAS) was reported to remarkably improve the production of short-chain fatty acids (SCFAs), especially propionic acid via simultaneously accelerating solubilization and hydrolysis, enhancing acidification, inhibiting methanogenesis and balancing carbon to nitrogen (C/N) ratio of substrate. Not only the production of SCFAs, especially propionic acid, was significantly improved by APG, but also the feasible operation time was shortened. The SCFAs yield at 0.3 g APG per gram of total suspended solids (TSS) within 4 d was 2988 ± 60 mg chemical oxygen demand (COD) per liter, much higher than that those from sole WAS or sole WAS plus sole APG. The corresponding yield of propionic acid was 1312 ± 25 mg COD/L, 7.9-fold of sole WAS. Mechanism investigation showed that during anaerobic treatment of WAS in the presence of APG both the solubilization and hydrolysis were accelerated and the acidification was enhanced, while the methanogenesis was inhibited. Moreover, the activities of key enzymes involved in WAS hydrolysis and acidification were improved through the adjustment of C/N ratio of substrates with APG. The abundance of microorganisms responsible for organic compounds hydrolysis and SCFAs production was also observed to be greatly enhanced with APG via 454 high-throughput pyrosequencing analysis.

  9. Dielectric properties of liquid-crystal azomethine polymer with a side alkyl-substituted chain, doped with fullerene C60

    NASA Astrophysics Data System (ADS)

    Kovalev, D. S.; Kostromin, S. V.; Musteaţa, V.; Cozan, V.; Bronnikov, S. V.

    2016-04-01

    We studied the actual and imaginary components of the dielectric constant of liquid-crystal azomethine polymer with a side chain, doped with 0.5 wt % of fullerene C60, over a wide range of temperatures and frequencies; measurements were made by means of dielectric spectroscopy. By analyzing the frequency dependence of the dielectric constant, we detected the relaxation processes (α, β1, and β2) in the nanocomposite, corresponding to certain modes of molecular motion and described them by the Arrhenius equations (β1- and β2-processes) and the Vogel-Fulcher-Tamman equation (α-process). An antiplasticization effect is discovered after doping the polymer with fullerene C60, which manifests itself in increasing the glass transition temperature of the nanocomposite compared to this parameter typical of pure polymer.

  10. Chemistry of anthracene-acetylene oligomers XXV: on-surface chirality of a self-assembled molecular network of a fan-blade-shaped anthracene-acetylene macrocycle with a long alkyl chain.

    PubMed

    Tsuya, Takuya; Iritani, Kohei; Tahara, Kazukuni; Tobe, Yoshito; Iwanaga, Tetsuo; Toyota, Shinji

    2015-03-27

    An anthracene cyclic dimer with two different linkers and a dodecyl group was synthesized by means of coupling reactions. The calculated structure had a planar macrocyclic π core and a linear alkyl chain. Scanning tunneling microscopy observations at the 1-phenyloctane/graphite interface revealed that the molecules formed a self-assembled monolayer that consisted of linear striped bright and dark bands. In each domain, the molecular network consisted of either Re or Si molecules that differed in the two-dimensional chirality about the macrocyclic faces, which led to a unique conglomerate-type self-assembly. The molecular packing mode and the conformation of the alkyl chains are discussed in terms of the intermolecular interactions and the interactions between the molecules and the graphite surface with the aid of MM3 simulations of a model system.

  11. Regulation of adipose branched-chain amin acid catabolism enzyme expression and cross-adipose amino acid flux in human obesity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elevated blood branched-chain amin acids (BCAA)are often assoicated with insulin resistance and type2 diabetes, which might result from a reduced cellular utilization and/or incomplete BCAA oxidation. White adipose tissue (WAT) has become appreciated as a potential player in whole body BCAA metaboli...

  12. Effects of branched-chain amino acid-enriched nutrient mixture on natural killer cell activity in viral cirrhosis.

    PubMed

    Takegoshi, K; Nanasawa, H; Itoh, H; Yasuyama, T; Ohmoto, Y; Sugiyama, K

    1998-06-01

    A controlled study was performed in 18 viral cirrhosis patients to evaluate whether immune function, as indicated by natural killer (NK) cell activity, was improved by a branched-chain amino acid-enriched nutrient mixture (nutrient-mixture), Aminoleban EN. Five patients received the nutrient-mixture (100 g/day) for 2 to 6 weeks preceded by control periods. Five additional patients received the nutrient-mixture for 2 to 4 weeks, and the remaining 8 patients did not receive the nutrient-mixture. NK cell activity, CD16, CD8, CD11b, and amino acids were assayed before and after the administration of the drug in the nutrient-mixture-supplemented group, and two times with 1 to 6 month intervals in the control group. In the nutrient-mixture-supplemented group (n = 10), increasing NK cell activity, expressed as the ratio of values of post-treatment to that of baseline (ratio > 1.25) was detected in 7 (70%) patients, whereas in the control group (n = 13), it was detected in only 1 (7.7%) (p < 0.01). While in the affected group (NK cell activity ratio > 1.25, n = 7), all patients had compensated liver cirrhosis, in the unaffected group (NK cell activity ratio < 1.25, n = 3), 2 of 3 patients had decompensated liver cirrhosis (p < 0.02). Laboratory data, indicating severity of liver cirrhosis, such as total bilirubin and albumin, showed better values (p < 0.01, p < 0.05 respectively), and baseline NK cell activity was low (8.7 +/- 7.2% vs 33.3 +/- 13.0%, p < 0.05) in the affected group than unaffected group. NK cell subpopulations such as CD16 (%), CD11b (%) and one of the populations of T cell such as CD8 (%) showed no significant change throughout the study. As for amino acids analysis, Fischer's ratio was increased in the nutrient-mixture-supplemented group compared to the control group (p < 0.05), but none of the amino acids showed significant change. Thus the changes in NK cell activity were not explained by increase in NK cell subpopulations nor changes of amino acids

  13. Simvastatin increases liver branched-chain α-ketoacid dehydrogenase activity in rats fed with low protein diet.

    PubMed

    Knapik-Czajka, Malgorzata

    2014-11-01

    The rate-limiting step in branched-chain amino acids (BCAAs) disposal is catalyzed by the mitochondrial branched-chain α-ketoacid dehydrogenase complex (BCKDH). BCKDH activity is regulated mainly by a reversible dephosphorylation (activation)/phosphorylation (inactivation) cycle catalyzed by a specific phosphatase (BDP) and kinase (BDK). Current catalytic activity of BCKDH, described as BCKDH activity state, and thus also BCAAs catabolic rate depend directly on the portion of BCKDH occurring in its active dephosphorylated form. Liver BCKDH activity state alters in response to different nutritional factors. Feeding rats a low-protein diet decreases BCKDH activity. It has been previously shown that lipid lowering drugs, fibrates upregulate liver BCKDH activity and stimulate BCAAs catabolism, especially under the condition of dietary protein deprivation. Effect of statins on liver BCKDH activity has not been studied yet. The present study was aimed at investigating the in vivo effect of simvastatin on liver BCKDH activity, as well as E1, E2 and BDP and BDK mRNA levels in rats fed with either a standard (23% protein) or a low protein (8% protein) diet. For 14 days, simvastatin (80 mg/kg b wt/day) or the vehicle (0.3% methylcellulose) were administrated orally by gavage to the treated and control groups, respectively. The actual BCKDH and total BCKDH activities were assayed spectrophotometrically prior to and following incubation with lambda phosphatase, respectively. The mRNA levels of the selected genes were quantified by means of a semi-quantitative RT-PCR. In rats fed with the low protein diet simvastatin administration reversed physiological adaptation of liver BCKDH to protein restriction and increased liver BCKDH activity state by 39% (p<0.05). Changes in BCKDH activity did not correspond to any changes in mRNA levels for BCKDH catalytic and regulatory enzymes. On the contrary, in rats fed with standard diet liver BCKDH activity state did not alter substantially

  14. Stimulation of rat liver branched-chain alpha-keto acid dehydrogenase activity by low doses of bezafibrate.

    PubMed

    Knapik-Czajka, Malgorzata

    2013-04-01

    Multienzyme branched-chain alpha-ketoacid dehydrogenase complex (BCKDH) catalyzes the regulatory step of oxidative catabolism of indispensable branched-chain amino acids (BCAA). The activity of the BCKDH complex is regulated by a reversible phosphorylation, end-product inhibition and by changes in the gene expression of BCKDH component enzymes. It has been shown previously that a high dose of bezafibrate (an agent added to rat chow at final concentration of 0.5%) changes mRNA levels of BCKDH-related enzymes and increases dephosphorylation of the complex leading to stimulation of liver BCKDH activity and the enhanced BCAA catabolism. The aim of the present study was to determine an in vivo effect of low, clinically relevant doses of bezafibrate on BCKDH activity in rat liver. Bezafibrate was administrated for 14 days by gastric gavage to Wistar male rats (fed low-protein chow; 8% protein) at one of the following daily doses of 5, 10 and 20mg/kgb.wt. The control group was given the vehicle (0.3% methylcellulose) only. The actual BCKDH and total BCKDH activities were assayed spectrophotometrically before and after incubation with a broad-specificity phosphatase, respectively. The mRNA levels of the selected genes (BCKDH catalytic subunits and regulatory enzymes) were quantified by means of semi-quantitative RT-PCR. Current catalytic activity of BCKDH (described as BCKDH activity state - the proportion of the BCKDH complex in its active dephosphorylated form) increased by 2.1 ± 0.2, 2.3 ± 0.2 and 2.7 ± 0.2 fold (p<0.01). Changes in BCKDH activity did not correspond with changes in mRNA levels of the complex catalytic subunits. Moreover, mRNA levels of regulatory enzymes remained unaltered. Initially bezafibrate caused a transient insignificant reduction in body weight, but it had no effect on the final body weight. The highest dose of bezafibrate induced hepatomegaly. In conclusion, these data indicate that under conditions of dietary protein restriction low

  15. Isovaleryl-homoserine lactone, an unusual branched-chain quorum-sensing signal from the soybean symbiont Bradyrhizobium japonicum.

    PubMed

    Lindemann, Andrea; Pessi, Gabriella; Schaefer, Amy L; Mattmann, Margrith E; Christensen, Quin H; Kessler, Aline; Hennecke, Hauke; Blackwell, Helen E; Greenberg, E Peter; Harwood, Caroline S

    2011-10-01

    Many species of Proteobacteria communicate by using LuxI-LuxR-type quorum-sensing systems that produce and detect acyl-homoserine lactone (acyl-HSL) signals. Most of the known signals are straight-chain fatty acyl-HSLs, and evidence indicates that LuxI homologs prefer fatty acid-acyl carrier protein (ACP) over fatty acyl-CoA as the acyl substrate for signal synthesis. Two related LuxI homologs, RpaI and BtaI from Rhodopseudomonas palustris and photosynthetic stem-nodulating bradyrhizobia, direct production of the aryl-HSLs p-coumaroyl-HSL and cinnamoyl-HSL, respectively. Here we report that BjaI from the soybean symbiont Bradyrhizobium japonicum USDA110 is closely related to RpaI and BtaI and catalyzes the synthesis of isovaleryl-HSL (IV-HSL), a branched-chain fatty acyl-HSL. We show that IV-HSL induces expression of bjaI, and in this way IV-HSL functions like many other acyl-HSL quorum-sensing signals. Purified histidine-tagged BjaI was an IV-HSL synthase, which was active with isovaleryl-CoA but not detectably so with isovaleryl-ACP. This suggests that the RpaI-BtaI-BjaI subfamily of acyl-HSL synthases may use CoA- rather than ACP-linked substrates for acyl-HSL synthesis. The bjaI-linked bjaR(1) gene is involved in the response to IV-HSL, and BjaR(1) is sensitive to IV-HSL at concentrations as low as 10 pM. Low but sufficient levels of IV-HSL (about 5 nM) accumulate in B. japonicum culture fluid. The low levels of IV-HSL synthesis have likely contributed to the fact that the quorum-sensing signal from this bacterium has not been described elsewhere.

  16. Influence of Alkyl Chain Length and Structure on the Extraction of Copper(II) from Aqueous Acid by 5-Alkyl-2-hydroxybenzaldoximes in Hydrocarbon Solvents: Diffusion Coefficients of Extractants and Their Complexes.

    PubMed

    Ainscow; Aldalur; Beezer; Connor; Garbett; Mitchell; Page; Tindale; Turner; Willson

    1999-05-01

    Measurement of the kinetics of extraction of copper(II) by 19 different 5-alkyl-2-hydroxybenzaldoximes (alkyl is C7H15 and C9H19) from acidic (hydrogen sulfate buffer) aqueous solution in the range pH 3.4-2.0, into 20% v/v toluene in n-hexane is reported. The lowering of the interfacial tension has been measured in some cases. The solubility of the extractants in water has been measured spectrophotometrically. A modified Taylor-Aris dispersion technique has been used to measure the diffusion coefficients in n-hexane and Orfom SX7 of some of the extractants and of the copper(II) complexes which they form. At low initial bulk concentrations (<10 mol m-3) of the extractants, the rate of extraction is controlled by the rate of diffusion of the extractant from the bulk to the organic-aqueous interface. The diffusion coefficient is related to the steric bulk of the alkyl substituent. At higher initial bulk concentrations (200 mol m-3) of the extractants, when the interface is saturated, the rate of extraction is inversely related to the apparent steric bulk of the alkyl substituent. Copyright 1999 Academic Press.

  17. Quantification of branched-chain keto acids in tissue by ultra fast liquid chromatography-mass spectrometry.

    PubMed

    Olson, Kristine C; Chen, Gang; Lynch, Christopher J

    2013-08-15

    Branched-chain keto acids (BCKAs) are associated with increased susceptibility to several degenerative diseases. However, BCKA concentrations in tissues or the amounts of tissue available are frequently at the limit of detection for standard plasma methods. To accurately and quickly determine tissue BCKAs, we have developed a sensitive ultra fast liquid chromatography-mass spectrometry (UFLC-MS) method. BCKAs from deproteinized tissue extractions were o-phenylenediamine (OPD) derivatized, ethyl acetate extracted, lyophilized in a vacuum centrifuge, and reconstituted in 200 mM ammonium acetate. Samples were injected onto a Shimadzu UFLC system coupled to an AB-Sciex 5600 Triple TOF mass spectrometer instrument that detected masses of the OPD BCKA products using a multiple reaction monitoring method. An OPD-derivatized (13)C-labeled keto acid was used as an internal standard. Application of the method for C57BL/6J (wild-type) and PP2Cm knockout mouse tissues, including kidney, adipose tissue, liver, gastrocnemius, and hypothalamus, is shown. The lowest tissue concentration measured by this method was 20 nM, with the standard curve covering a wide range (7.8-32,000 nM). Liquid chromatography-mass spectrometry run times for this assay were less than 5 min, facilitating high throughput, and the OPD derivatives were found to be stable over several days.

  18. The influence of alternative pathways of respiration that utilize branched-chain amino acids following water shortage in Arabidopsis.

    PubMed

    Pires, Marcel V; Pereira Júnior, Adilson A; Medeiros, David B; Daloso, Danilo M; Pham, Phuong Anh; Barros, Kallyne A; Engqvist, Martin K M; Florian, Alexandra; Krahnert, Ina; Maurino, Veronica G; Araújo, Wagner L; Fernie, Alisdair R

    2016-06-01

    During dark-induced senescence isovaleryl-CoA dehydrogenase (IVDH) and D-2-hydroxyglutarate dehydrogenase (D-2HGDH) act as alternate electron donors to the ubiquinol pool via the electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase (ETF/ETFQO) pathway. However, the role of this pathway in response to other stresses still remains unclear. Here, we demonstrated that this alternative pathway is associated with tolerance to drought in Arabidopsis. In comparison with wild type (WT) and lines overexpressing D-2GHDH, loss-of-function etfqo-1, d2hgdh-2 and ivdh-1 mutants displayed compromised respiration rates and were more sensitive to drought. Our results demonstrated that an operational ETF/ETFQO pathway is associated with plants' ability to withstand drought and to recover growth once water becomes replete. Drought-induced metabolic reprogramming resulted in an increase in tricarboxylic acid (TCA) cycle intermediates and total amino acid levels, as well as decreases in protein, starch and nitrate contents. The enhanced levels of the branched-chain amino acids in loss-of-function mutants appear to be related to their increased utilization as substrates for the TCA cycle under water stress. Our results thus show that mitochondrial metabolism is highly active during drought stress responses and provide support for a role of alternative respiratory pathways within this response.

  19. Branched-chain amino acid supplementation does not enhance athletic performance but affects muscle recovery and the immune system.

    PubMed

    Negro, M; Giardina, S; Marzani, B; Marzatico, F

    2008-09-01

    Since the 1980's there has been high interest in branched-chain amino acids (BCAA) by sports nutrition scientists. The metabolism of BCAA is involved in some specific biochemical muscle processes and many studies have been carried out to understand whether sports performance can be enhanced by a BCAA supplementation. However, many of these researches have failed to confirm this hypothesis. Thus, in recent years investigators have changed their research target and focused on the effects of BCAA on the muscle protein matrix and the immune system. Data show that BCAA supplementation before and after exercise has beneficial effects for decreasing exercise-induced muscle damage and promoting muscle-protein synthesis. Muscle damage develops delayed onset muscle soreness: a syndrome that occurs 24-48 h after intensive physical activity that can inhibit athletic performance. Other recent works indicate that BCAA supplementation recovers peripheral blood mononuclear cell proliferation in response to mitogens after a long distance intense exercise, as well as plasma glutamine concentration. The BCAA also modifies the pattern of exercise-related cytokine production, leading to a diversion of the lymphocyte immune response towards a Th1 type. According to these findings, it is possible to consider the BCAA as a useful supplement for muscle recovery and immune regulation for sports events. PMID:18974721

  20. Effect of branched-chain fatty acids, 3-methylindole and 4-methylphenol on consumer sensory scores of grilled lamb meat.

    PubMed

    Watkins, P J; Kearney, G; Rose, G; Allen, D; Ball, A J; Pethick, D W; Warner, R D

    2014-02-01

    Tenderness, flavour, overall liking and odour are important components of sheepmeat eating quality. Consumer assessment of these attributes has been made for carcasses from the Information Nucleus Flock (INF) of the Cooperative Research Centre for Sheep Industry Innovation. The concentrations of three branched chain fatty acids, 4-methyloctanoic (MOA), 4-ethyloctanoic (EOA) and 4-methylnonanoic acids (compounds related to 'mutton flavour' in cooked sheepmeat) and 3-methylindole and 4-methylphenol (compounds related to 'pastoral' flavour) were determined for 178 fat samples taken from INF carcasses. Statistical modelling revealed that both MOA and EOA impacted on the 'Like Smell' consumer sensory score of the cooked meat product (P<0.05), with increasing concentration causing lower consumer acceptance of the product. None of the compounds though had an effect on the liking of flavour. Obviously, reducing the effect of MOA and EOA on the odour of grilled lamb will improve consumer acceptance of the cooked product but other factors affecting the eating quality also need to be considered. PMID:22950976

  1. Isothermal chain-branching, reaction exothermicity, and transport interactions in the stability of methane/air mixtures

    SciTech Connect

    Park, Y.K.; Vlachos, D.G.

    1998-07-01

    The influence of reaction exothermicity and transport of species on the bifurcation behavior of CH{sub 4}/air mixtures is studied in a continuous stirred tank reactor with numerical bifurcation techniques, using the 177-reaction/31-species Gas Research Institute mechanism, version 1.2. Ignition points are analyzed through various sensitivity analyses, quasi-steady-state analysis, and numerical experiments. Principal component analysis is also applied at ignition to derive a reduced 28-reaction mechanism capable of accurately predicting ignition temperature as a function of pressure at intermediate to high pressures. Results show that isothermal chain-branching chemistry can drive complex instabilities, with up to five multiple solutions and Hopf bifurcations. However, thermal feedback (reaction exothermicity) promotes ignition and considerably extends the range of multiplicity with respect to pressure, residence time, and inlet CH{sub 4} concentration. Reaction exothermicity eliminates a turning-back behavior and results in a monotonic pressure-temperature ignition diagram. This ignition pressure-temperature stability diagram considerably shifts with residence time, especially at low pressures. It is shown that this shift in ignition temperature is mainly due to transport of CH{sub 2}O at high pressures and transport of CH{sub 3} radicals at low pressures. Sensitivity analyses with respect to heats of reactions and reaction preexponentials reveal a strong coupling between kinetic and thermal interactions in controlling ignition. Qualitative comparison with experiments is also performed, and results are briefly contrasted to H{sub 2}/air ignition.

  2. New therapeutic strategy for amino acid medicine: notable functions of branched chain amino acids as biological regulators.

    PubMed

    Yoshizawa, Fumiaki

    2012-01-01

    The branched chain amino acids (BCAAs) leucine, isoleucine, and valine are the most abundant of the essential amino acids. BCAAs have recently been recognized as having functions other than simple nutrition. The importance of BCAAs as nutrient regulators in protein synthesis was recognized over 20 years ago. Leucine is the most potent of the BCAAs in stimulating muscle protein synthesis, while isoleucine and valine are much less effective. The signaling action of leucine in protein synthesis has been well studied, and the mechanisms are currently under investigation. However, the pharmacological effects of isoleucine and valine have not been clarified. It has recently been reported that, among the BCAAs, leucine and isoleucine act as signals in glucose metabolism. We revealed that isoleucine stimulates both glucose uptake in the muscle and whole body glucose oxidation, in addition to depressing gluconeogenesis in the liver, thereby leading to a hypoglycemic effect in rats. Based on these results, we speculate that isoleucine signaling accelerates catabolism of incorporated glucose for energy production and consumption.

  3. Electrochemical Branched-DNA Assay for Polymerase Chain Reaction-Free Detection and Quantification of Oncogenes in Messenger RNA

    SciTech Connect

    Lee, Ai Cheng; Dai, Ziyu; Chen, Baowei; Wu, Hong; Wang, Jun; Zhang, Aiguo; Zhang, Lurong; Lim, Tit-Meng; Lin, Yuehe

    2008-12-01

    We describe a novel electrochemical branched-DNA (bDNA) assay for polymerase chain reaction (PCR)-free detection and quantification of p185 BCR-ABL leukemia fusion transcript in the population of messenger RNA (mRNA) extracted from cell lines. The bDNA amplifier carrying high loading of alkaline phosphatase (ALP) tracers was used to amplify targets signal. The targets were captured on microplate well surfaces through cooperative sandwich hybridization prior to the labeling of bDNA. The activity of captured ALP was monitored by square-wave voltammetric (SWV) analysis of the electroactive enzymatic product in the presence of 1-napthyl-phosphate. The specificity and sensitivity of assay enabled direct detection of target transcript in as little as 4.6 ng mRNA without PCR amplification. In combination with the use of a well-quantified standard, the electrochemical bDNA assay was capable of direct use for a PCR-free quantitative analysis of target transcript in total mRNA population. The approach thus provides a simple, sensitive, accurate and quantitative tool alternate to the RQ-PCR for early disease diagnosis.

  4. Branched Chain Fatty Acid Content of United States Retail Cow’s Milk and Implications for Dietary Intake

    PubMed Central

    Ran-Ressler, R. R.; Sim, D.; Brenna, J. T.; O’Donnell-Megaro, A. M.; Bauman, D. E.; Barbano, D. M.

    2011-01-01

    Branched chain fatty acids (BCFA) have recently been shown to be a major component of the normal human newborn gastrointestinal tract and have long been known to be a component of human milk. Ruminant food products are major sources of fat in the American diet, but there are no studies of milkfat BCFA content in retail milk. We report here the profile and concentrations of BCFA in a representative sampling of retail milk in the 48 contiguous United States (US), and their estimated intake in the American diet. Conventionally produced whole fluid milk samples were obtained from 56 processing plants across the contiguous 48 states. Retail milk samples contain exclusively iso- and anteiso-BCFA with 14–18 carbons. BCFA were 2.05 ± 0.14%, w/w of milkfat fatty acids (mean ± SD), and anteiso-BCFA comprised more than half this total. Based on these data and USDA food availability data, the average per capita BCFA intake of Americans is estimated to be about 220 mg/d from dairy; if current dietary recommendations were followed, BCFA intake would be about 400 mg/d. Adding intake from beef consumption, these estimates rise to approximately 400 and 575 mg/d, respectively. These results indicate that BCFA intake is a substantial fraction of daily fat intake, in amounts exceeding those of many bioactive fatty acids. PMID:21293946

  5. The influence of alternative pathways of respiration that utilize branched-chain amino acids following water shortage in Arabidopsis.

    PubMed

    Pires, Marcel V; Pereira Júnior, Adilson A; Medeiros, David B; Daloso, Danilo M; Pham, Phuong Anh; Barros, Kallyne A; Engqvist, Martin K M; Florian, Alexandra; Krahnert, Ina; Maurino, Veronica G; Araújo, Wagner L; Fernie, Alisdair R

    2016-06-01

    During dark-induced senescence isovaleryl-CoA dehydrogenase (IVDH) and D-2-hydroxyglutarate dehydrogenase (D-2HGDH) act as alternate electron donors to the ubiquinol pool via the electron-transfer flavoprotein/electron-transfer flavoprotein:ubiquinone oxidoreductase (ETF/ETFQO) pathway. However, the role of this pathway in response to other stresses still remains unclear. Here, we demonstrated that this alternative pathway is associated with tolerance to drought in Arabidopsis. In comparison with wild type (WT) and lines overexpressing D-2GHDH, loss-of-function etfqo-1, d2hgdh-2 and ivdh-1 mutants displayed compromised respiration rates and were more sensitive to drought. Our results demonstrated that an operational ETF/ETFQO pathway is associated with plants' ability to withstand drought and to recover growth once water becomes replete. Drought-induced metabolic reprogramming resulted in an increase in tricarboxylic acid (TCA) cycle intermediates and total amino acid levels, as well as decreases in protein, starch and nitrate contents. The enhanced levels of the branched-chain amino acids in loss-of-function mutants appear to be related to their increased utilization as substrates for the TCA cycle under water stress. Our results thus show that mitochondrial metabolism is highly active during drought stress responses and provide support for a role of alternative respiratory pathways within this response. PMID:26616144

  6. FgIlv5 is required for branched-chain amino acid biosynthesis and full virulence in Fusarium graminearum.

    PubMed

    Liu, Xin; Wang, Jian; Xu, Jianhong; Shi, Jianrong

    2014-04-01

    In this study, we characterized FgIlv5, a homologue of the Saccharomyces cerevisiae keto-acid reductoisomerase (KARI) from the important wheat head scab fungus Fusarium graminearum. KARI is a key enzyme in the branched-chain amino acid (BCAA, including leucine, isoleucine and valine) biosynthetic pathway that exists in a variety of organisms from bacteria to fungi and higher plants, but not in mammals. The FgILV5 deletion mutant ΔFgIlv5-4 failed to grow when the culture medium was nutritionally limited for BCAAs. When grown on potato-dextrose agar plates, ΔFgIlv5-4 exhibited a significant decrease in aerial hyphae formation and red pigmentation. Conidia formation was also blocked in ΔFgIlv5-4. Exogenous addition of 1 mM isoleucine and valine was able to rescue the defects of mycelial growth and conidial morphogenesis. Cellular stress assays showed that ΔFgIlv5-4 was more sensitive to osmotic and oxidative stresses than the wild-type strain. In addition, virulence of ΔFgIlv5-4 was dramatically reduced on wheat heads, and a low level of deoxynivalenol production was detected in ΔFgIlv5-4 in wheat kernels. The results of this study indicate that FgIlv5 is involved in valine and isoleucine biosynthesis and is required for full virulence in F. graminearum.

  7. Oral branched-chain amino acid supplements that reduce brain serotonin during exercise in rats also lower brain catecholamines.

    PubMed

    Choi, Sujean; Disilvio, Briana; Fernstrom, Madelyn H; Fernstrom, John D

    2013-11-01

    Exercise raises brain serotonin release and is postulated to cause fatigue in athletes; ingestion of branched-chain amino acids (BCAA), by competitively inhibiting tryptophan transport into brain, lowers brain tryptophan uptake and serotonin synthesis and release in rats, and reputedly in humans prevents exercise-induced increases in serotonin and fatigue. This latter effect in humans is disputed. But BCAA also competitively inhibit tyrosine uptake into brain, and thus catecholamine synthesis and release. Since increasing brain catecholamines enhances physical performance, BCAA ingestion could lower catecholamines, reduce performance and thus negate any serotonin-linked benefit. We therefore examined in rats whether BCAA would reduce both brain tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis. Sedentary and exercising rats received BCAA or vehicle orally; tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis rates were measured 1 h later in brain. BCAA reduced brain tryptophan and tyrosine concentrations, and serotonin and catecholamine synthesis. These reductions in tyrosine concentrations and catecholamine synthesis, but not tryptophan or serotonin synthesis, could be prevented by co-administering tyrosine with BCAA. Complete essential amino acid mixtures, used to maintain or build muscle mass, were also studied, and produced different effects on brain tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis. Since pharmacologically increasing brain catecholamine function improves physical performance, the finding that BCAA reduce catecholamine synthesis may explain why this treatment does not enhance physical performance in humans, despite reducing serotonin synthesis. If so, adding tyrosine to BCAA supplements might allow a positive action on performance to emerge.

  8. Branched-chain amino acids are associated with cardiometabolic risk profiles found already in lean, overweight and obese young.

    PubMed

    Mangge, Harald; Zelzer, Sieglinde; Prüller, Florian; Schnedl, Wolfgang J; Weghuber, Daniel; Enko, Dietmar; Bergsten, Peter; Haybaeck, Johannes; Meinitzer, Andreas

    2016-06-01

    Cardiovascular risk is increased in obese subjects. Nevertheless, some overweight and obese remain cardiometabolically healthy (CMH), and normal-weight persons develop cardiovascular disease (CVD). Herein, we investigate the potential of branched-chain amino acids (BCAAs) to identify an increased CVD risk in a cross-sectional study of 666 adults and juveniles (age 25.3±12.8years), classified as lean, overweight or obese. Cardiometabolic groups were defined by cutoffs of systolic blood pressure<130mmHg, diastolic blood pressure<85mmHg, glucose<125mg/dl, triglycerides<150mg/dl, HDL-cholesterol>40mg/dl (males), HDL-cholesterol>50mg/dl (females) and HOMA-IR<5. CMH had ≤1 cutoff, and cardiometabolically abnormal (CMA) had ≥2 cutoffs. Amino acids were measured by high-pressure lipid chromatography after precipitation of serum with perchloric acid and derivatization with o-phthalaldehyde. Valine correlated with 5, leucine correlated with 3 and isoleucine correlated with 5 of the cardiac risk classification factors. Valine and leucine were significantly higher in the obese (P<.001, P=.015, respectively), overweight (P<.001, P=.015, respectively) and lean (P=.024, P=.012, respectively) CMA compared to CMH subjects. Isoleucine showed except of the lean group the same results. Taken together, BCAAs, especially valine and leucine, are proposed as a cardiometabolic risk marker independent of body mass index (BMI) category. PMID:27142745

  9. Influence of molecular architecture on the entanglement network: topological analysis of linear, long- and short-chain branched polyethylene melts via Monte Carlo simulations.

    PubMed

    Jeong, Seung Heum; Kim, Jun Mo; Yoon, Jeongha; Tzoumanekas, Christos; Kröger, Martin; Baig, Chunggi

    2016-04-20

    We present detailed results on the effect of chain branching on the topological properties of entangled polymer melts via an advanced connectivity-altering Monte Carlo (MC) algorithm. Eleven representative model linear, short-chain branched (SCB), and long-chain branched (LCB) polyethylene (PE) melts were employed, based on the total chain length and/or the longest linear chain dimension. Directly analyzing the entanglement [or the primitive path (PP)] network of the system via the Z-code, we quantified several important topological measures: (a) the PP contour length Lpp, (b) the number of entanglements Zes per chain, (c) the end-to-end length of an entanglement strand des, (d) the number of carbon atoms per entanglement strand Nes, and (e) the probability distribution for each of these quantities. The results show that the SCB polymer melts have significantly more compact overall chain conformations compared to the linear polymers, exhibiting, relative to the corresponding linear analogues, (a) ∼20% smaller values of 〈Lpp〉 (the statistical average of Lpp), (b) ∼30% smaller values of 〈Zes〉, (c) ∼20% larger values of 〈des〉, and (d) ∼50% larger values of 〈Nes〉. In contrast, despite the intrinsically smaller overall chain dimensions than those of the linear analogues, the LCB (H-shaped and A3AA3 multiarm) PE melts exhibit relatively (a) 7-8% larger values of 〈Lpp〉, (b) 6-11% larger values of 〈Zes〉 for the H-shaped melt and ∼2% smaller values of 〈Zes〉 for the A3AA3 multiarm, (c) 2-5% smaller values of 〈des〉, and (d) 7-11% smaller values of 〈Nes〉. Several interesting features were also found in the results of the probability distribution functions P for each topological measure.

  10. Whey protein supplementation does not alter plasma branched-chained amino acid profiles but results in unique metabolomics patterns in obese women enrolled in an 8-week weight loss trial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background. Elevations of plasma concentrations of branched-chain amino acids (BCAA) are correlated with insulin resistance. Reduction in the activity of branched-chain ketoacid dehydrogenase complex (BCKDC) activity and impaired complete mitochondrial BCAA catabolism may contribute to this phenoty...

  11. N-acetyl-D-glucosamine kinase interacts with dynein light-chain roadblock type 1 at Golgi outposts in neuronal dendritic branch points

    PubMed Central

    Islam, Md Ariful; Sharif, Syeda Ridita; Lee, HyunSook; Seog, Dae-Hyun; Moon, Il Soo

    2015-01-01

    N-acetylglucosamine kinase (GlcNAc kinase or NAGK) is a ubiquitously expressed enzyme in mammalian cells. Recent studies have shown that NAGK has an essential structural, non-enzymatic role in the upregulation of dendritogenesis. In this study, we conducted yeast two-hybrid screening to search for NAGK-binding proteins and found a specific interaction between NAGK and dynein light-chain roadblock type 1 (DYNLRB1). Immunocytochemistry (ICC) on hippocampal neurons using antibodies against NAGK and DYNLRB1 or dynein heavy chain showed some colocalization, which was increased by treating the live cells with a crosslinker. A proximity ligation assay (PLA) of NAGK-dynein followed by tubulin ICC showed the localization of PLA signals on microtubule fibers at dendritic branch points. NAGK-dynein PLA combined with Golgi ICC showed the colocalization of PLA signals with somal Golgi facing the apical dendrite and with Golgi outposts in dendritic branch points and distensions. NAGK-Golgi PLA followed by tubulin or DYNLRB1 ICC showed that PLA signals colocalize with DYNLRB1 at dendritic branch points and at somal Golgi, indicating a tripartite interaction between NAGK, dynein and Golgi. Finally, the ectopic introduction of a small peptide derived from the C-terminal amino acids 74–96 of DYNLRB1 resulted in the stunting of hippocampal neuron dendrites in culture. Our data indicate that the NAGK-dynein-Golgi tripartite interaction at dendritic branch points functions to regulate dendritic growth and/or branching. PMID:26272270

  12. Enriched branched-chain amino acid formula versus a casein-based supplement in the treatment of cirrhosis.

    PubMed

    Christie, M L; Sack, D M; Pomposelli, J; Horst, D

    1985-01-01

    An orally administered branched-chain amino acid (BCAA) rich supplement (T), Travasorb-Hepatic was compared to a casein based supplement (E), Ensure, in a randomized double-blind cross-over study in eight malnourished, stable cirrhotics unable to achieve a daily dietary protein intake of 1.0 g/kg. Doses of antiportal systemic encephalopathy drugs remained constant and a baseline 1000 kcal, 40 g dietary protein intake was encouraged. To this diet, supplemental protein was added in daily 20-g increments to a maximum of 60 g supplemental protein. Mental status, asterixis, and number connection tests were assessed daily and an antiportal systemic encephalopathy index calculated. There was no significant difference in the mean intake of dietary protein (T, 33.7 +/- 4.0 g; E, 26.7 +/- 10.8 g), supplemental protein (T, 43.1 +/- 8.3 g; E, 47.9 +/- 7.1 g), or N2 balance (T, 4.2 +/- 3.7 g; E, 3.4 +/- 4.4) between treatment trials. The antiportal systemic encephalopathy index improved on E, with no significant change in the BCAA:aromatic acid molar ratio. This ratio improved on T (1.02 +/- 2.0 to 2.7 +/- 1.1), but was not accompanied by improvement in the antiportal systemic encephalopathy index. The improved protein tolerance in both groups was not further increased by a highly enriched BCAA formula compared to one with a moderate BCAA content from a natural dietary protein source. Thus, both conventional casein-based supplements and enriched BCAA formulas are well tolerated and can be safely and effectively used as an integral part of diet therapy.

  13. The Supplementation of Branched-Chain Amino Acids, Arginine, and Citrulline Improves Endurance Exercise Performance in Two Consecutive Days

    PubMed Central

    Cheng, I-Shiung; Wang, Yi-Wen; Chen, I-Fan; Hsu, Gi-Sheng; Hsueh, Chun-Fang; Chang, Chen-Kang

    2016-01-01

    The central nervous system plays a crucial role in fatigue during endurance exercise. Branched-chain amino acids (BCAA) could reduce cerebral serotonin synthesis by competing with its precursor tryptophan for crossing the blood brain barrier. Arginine and citrulline could prevent excess hyperammonemia accompanied by BCAA supplementation. This study investigated the combination of BCAA, arginine, and citrulline on endurance performance in two consecutive days. Seven male and three female endurance runners ingested 0.17 g·kg-1 BCAA, 0.05 g·kg-1 arginine and 0.05 g·kg-1 citrulline (AA trial) or placebo (PL trial) in a randomized cross-over design. Each trial contained a 5000 m time trial on the first day, and a 10000 m time trial on the second day. The AA trial had significantly better performance in 5000 m (AA: 1065.7 ± 33.9 s; PL: 1100.5 ± 40.4 s) and 10000 m (AA: 2292.0 ± 211.3 s; PL: 2375.6 ± 244.2 s). The two trials reported similar ratings of perceived exertion. After exercise, the AA trial had significantly lower tryptophan/BCAA ratio, similar NH3, and significantly higher urea concentrations. In conclusion, the supplementation could enhance time-trial performance in two consecutive days in endurance runners, possibly through the inhibition of cerebral serotonin synthesis by BCAA and the prevention of excess hyperammonemia by increased urea genesis. Key points The combined supplementation of BCAA, arginine, and citrulline could enhance performance in 5000 m and 10000 m in 2 consecutive days in competitive runners. The supplementation may be helpful in multi-day competitions. The supplemented BCAA may alleviate central fatigue, allowing the subjects to run faster at the same degree of perceived exertion. The hyperammonemia that is usually accompanied with BCAA supplementation may be prevented by arginine and citrulline through increased urea genesis. PMID:27803630

  14. Oral branched-chain amino acid supplements that reduce brain serotonin during exercise in rats also lower brain catecholamines.

    PubMed

    Choi, Sujean; Disilvio, Briana; Fernstrom, Madelyn H; Fernstrom, John D

    2013-11-01

    Exercise raises brain serotonin release and is postulated to cause fatigue in athletes; ingestion of branched-chain amino acids (BCAA), by competitively inhibiting tryptophan transport into brain, lowers brain tryptophan uptake and serotonin synthesis and release in rats, and reputedly in humans prevents exercise-induced increases in serotonin and fatigue. This latter effect in humans is disputed. But BCAA also competitively inhibit tyrosine uptake into brain, and thus catecholamine synthesis and release. Since increasing brain catecholamines enhances physical performance, BCAA ingestion could lower catecholamines, reduce performance and thus negate any serotonin-linked benefit. We therefore examined in rats whether BCAA would reduce both brain tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis. Sedentary and exercising rats received BCAA or vehicle orally; tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis rates were measured 1 h later in brain. BCAA reduced brain tryptophan and tyrosine concentrations, and serotonin and catecholamine synthesis. These reductions in tyrosine concentrations and catecholamine synthesis, but not tryptophan or serotonin synthesis, could be prevented by co-administering tyrosine with BCAA. Complete essential amino acid mixtures, used to maintain or build muscle mass, were also studied, and produced different effects on brain tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis. Since pharmacologically increasing brain catecholamine function improves physical performance, the finding that BCAA reduce catecholamine synthesis may explain why this treatment does not enhance physical performance in humans, despite reducing serotonin synthesis. If so, adding tyrosine to BCAA supplements might allow a positive action on performance to emerge. PMID:23904096

  15. Down-regulation of rat mitochondrial branched-chain 2-oxoacid dehydrogenase kinase gene expression by glucocorticoids.

    PubMed Central

    Huang, Y S; Chuang, D T

    1999-01-01

    The mammalian mitochondrial branched-chain 2-oxoacid dehydrogenase (BCOD) complex is regulated by a reversible phosphorylation (inactivation)/dephosphorylation (activation) cycle. In the present study, the effects of glucocorticoids on the level of BCOD kinase mRNA were investigated in rat hepatoma cell lines (H4IIE and FTO-2B), as well as in the rat. In H4IIE cells, dexamethasone was found to significantly reduce steady-state concentrations of BCOD kinase mRNA after a 48 h culture, and this was correlated with a 2-fold increase in the dephosphorylated form of the BCOD complex. The half-life of the kinase mRNA in H4IIE cells was not affected by dexamethasone treatment. Therefore, the decrease in the steady-state kinase mRNA level resulting from dexamethasone treatment was not caused by changes in mRNA stability, which raised the possibility of regulation at the level of gene transcription. To identify the negative glucocorticoid-responsive element in the kinase promoter, nested deletion constucts in the 3.0 kb promoter region were examined in H4IIE cells cultured in the presence or absence of dexamethasone. No significant differences in promoter activity were observed on either transient or stable transfection. The data showed that the glucocorticoid-responsive element was located outside the 3. 0 kb promoter region. At the physiological level, hepatic BCOD kinase mRNA levels were reduced in rats injected intraperitoneally with dexamethasone. This effect was liver-specific, and was not detected in other tissues. These results suggest that the down-regulation of kinase gene expression by glucocorticoids is mediated through a liver-specific or -enriched transcription factor(s). PMID:10215586

  16. The role of branched chain amino acid and tryptophan metabolism in rat's behavioral diversity: Intertwined peripheral and brain effects.

    PubMed

    Asor, Eyal; Stempler, Shiri; Avital, Avi; Klein, Ehud; Ruppin, Eytan; Ben-Shachar, Dorit

    2015-10-01

    Previously, we showed that a transient early-in-life interference with the expression of multiple genes by mithramycin (MTR) followed by later-in-life exposure to chronic stress, leads to a "daring" and novelty seeking behavior in rats. In this study we searched for molecular changes that contribute to this behavioral alteration. We applied a non-hypothesis driven strategy using whole genome cDNA array analysis (WGA) followed by Genome Scale Metabolic modeling analysis (GSMM). Gene expression validation was performed by qRT-PCR and immunoblotting. Brain and serum amino acids levels were measured by HPLC. WGA data directed us towards metabolic pathways and GSMM pointed at branched chain amino acids (BCAA) pathway. Out of 21 amino acids analyzed in the prefrontal cortex of MTR+Stress rats only tryptophan, whose brain levels depend on serum BCAA levels, showed a significant decrease. No change was observed in serotonin or kynurenine levels. However, a significant reduction in mRNA and protein levels of the large neutral amino acid transporter (LAT1), which transports BCAA and tryptophan into the brain, as well as in serum levels of tryptophan/BCAA ratio were observed. The latter may be attributed to the failure to increase serum insulin, following stress, in rats pre-exposed to mithramycin. Finally, significant correlations were observed between the anxiety index and tryptophan and between T-maze errors and LAT1. This study shows a specific behavioral pattern, which is linked to modulations in fluxes of amino acids both peripheral and central, which converge and reciprocally interact, and may thus be equally important targets for therapeutic intervention.

  17. Branched-Chain Amino Acids as New Biomarkers of Major Depression - A Novel Neurobiology of Mood Disorder

    PubMed Central

    Baranyi, Andreas; Amouzadeh-Ghadikolai, Omid; von Lewinski, Dirk; Rothenhäusler, Hans-Bernd; Theokas, Simon; Robier, Christoph; Mangge, Harald; Reicht, Gerhard; Hlade, Peter; Meinitzer, Andreas

    2016-01-01

    Background The proteinogenic branched-chain amino acids (BCAAs) valine, leucine and isoleucine might play an unrecognised crucial role in the development of depression through their activation of the mammalian target of rapamycin (mTor) pathway. The aim of this research project is to evaluate whether BCAAs are altered in patients with major depression and might thus be appropriate biomarkers for major depression. Methods The concentrations of valine, leucine and isoleucine were determined in 71 in-patients with major depression and 48 healthy controls by high-pressure liquid chromatography. Psychiatric and laboratory assessments were obtained at the time of in-patient admittance. Results The BCAAs are significantly decreased in patients with major depression in comparison with healthy subjects (valine: Mann-Whitney-U: 968.0; p <0.0001, leucine: Mann-Whitney-U: 1246.5; p = 0.013, isoleucine: Mann-Whitney-U: 1252.5; p = 0.014). Furthermore, as shown by Spearman's rank correlation coefficients, there is a significant negative correlation between valine, leucine and isoleucine concentrations and the Hamilton Depression Rating Scale (HAMD-17) as well as Beck Depression Inventory (BDI-II) scores. Conclusions Our study results are strong evidence that in patients with major depression, BCAAs might be appropriate biomarkers for depression. Reduced activation of the mammalian target of rapamycin (mTor) due to a reduction of BCAAs might play a crucial unrecognised factor in the etiology of depression and may evoke depressive symptomatology and lower energy metabolism in patients with major depression. In the future, mTor and its up- and downstream signalling partners might be important targets for the development of novel antidepressants. PMID:27490818

  18. The role of branched chain amino acid and tryptophan metabolism in rat's behavioral diversity: Intertwined peripheral and brain effects.

    PubMed

    Asor, Eyal; Stempler, Shiri; Avital, Avi; Klein, Ehud; Ruppin, Eytan; Ben-Shachar, Dorit

    2015-10-01

    Previously, we showed that a transient early-in-life interference with the expression of multiple genes by mithramycin (MTR) followed by later-in-life exposure to chronic stress, leads to a "daring" and novelty seeking behavior in rats. In this study we searched for molecular changes that contribute to this behavioral alteration. We applied a non-hypothesis driven strategy using whole genome cDNA array analysis (WGA) followed by Genome Scale Metabolic modeling analysis (GSMM). Gene expression validation was performed by qRT-PCR and immunoblotting. Brain and serum amino acids levels were measured by HPLC. WGA data directed us towards metabolic pathways and GSMM pointed at branched chain amino acids (BCAA) pathway. Out of 21 amino acids analyzed in the prefrontal cortex of MTR+Stress rats only tryptophan, whose brain levels depend on serum BCAA levels, showed a significant decrease. No change was observed in serotonin or kynurenine levels. However, a significant reduction in mRNA and protein levels of the large neutral amino acid transporter (LAT1), which transports BCAA and tryptophan into the brain, as well as in serum levels of tryptophan/BCAA ratio were observed. The latter may be attributed to the failure to increase serum insulin, following stress, in rats pre-exposed to mithramycin. Finally, significant correlations were observed between the anxiety index and tryptophan and between T-maze errors and LAT1. This study shows a specific behavioral pattern, which is linked to modulations in fluxes of amino acids both peripheral and central, which converge and reciprocally interact, and may thus be equally important targets for therapeutic intervention. PMID:26271721

  19. Usefulness of Levocarnitine and/or Branched-Chain Amino Acids during Invasive Treatment for Hepatocellular Carcinoma.

    PubMed

    Iwasa, Motoh; Sugimoto, Ryosuke; Ishihara, Tomoaki; Sekoguchi-Fujikawa, Noriko; Yoshikawa, Kyoko; Mifuji-Moroka, Rumi; Tanaka, Hideaki; Kobayashi, Yoshinao; Hasegawa, Hiroshi; Takei, Yoshiyuki

    2015-01-01

    Transarterial chemoembolization (TACE) and radiofrequency ablation (RFA) are effective treatments for hepatocellular carcinoma (HCC). However, the extent of treatment depends on hepatic functional reserve. L-Carnitine is a vitamin-like substance and several reports have described the usefulness of L-carnitine supplementation in cases of cirrhosis, with confirmed effectiveness against refractory hepatic encephalopathy. On the other hand, we have previously reported that in patients who underwent TACE or RFA, administration of branched-chain amino acids (BCAAs) pre-intervention significantly reduced inflammatory reactions. We first determined serum levels of total, free, and acyl-carnitine before and at 7 d after performing TACE in 10 HCC patients. We administered levocarnitine (L-carnitine chloride, a biologically active form of carnitine) at 900 mg/d to 69 consecutive HCC patients hospitalized to undergo TACE and/or RFA, and compared changes in blood test values with those in 119 consecutive patients not administered this drug. Sixty-seven patients had a history of using BCAAs at the time of admission. We found that after 7 d of TACE, serum levels of total and acyl-carnitine are significantly decreased. On comparing the four groups, the carnitine+BCAA, carnitine-alone, and BCAA-alone groups showed significantly higher values for changes in NH3 when compared with the non-dosed group. The decrease in albumin (Alb) was significantly suppressed in the carnitine+BCAA and BCAA-alone groups. We also conducted the same examinations in a subset of patients classified as Child-Pugh class A, and noted the same trends. Administration of levocarnitine and/or BCAAs during invasive treatments reduced blood NH3 concentrations and suppressed decreases in Alb. PMID:26875483

  20. Alkylating enzymes.

    PubMed

    Wessjohann, Ludger A; Keim, Jeanette; Weigel, Benjamin; Dippe, Martin

    2013-04-01

    Chemospecific and regiospecific modifications of natural products by methyl, prenyl, or C-glycosyl moieties are a challenging and cumbersome task in organic synthesis. Because of the availability of an increasing number of stable and selective transferases and cofactor regeneration processes, enzyme-assisted strategies turn out to be promising alternatives to classical synthesis. Two categories of alkylating enzymes become increasingly relevant for applications: firstly prenyltransferases and terpene synthases (including terpene cyclases), which are used in the production of terpenoids such as artemisinin, or meroterpenoids like alkylated phenolics and indoles, and secondly methyltransferases, which modify flavonoids and alkaloids to yield products with a specific methylation pattern such as 7-O-methylaromadendrin and scopolamine.

  1. Structure of epiglucan, a highly side-chain/branched (1 --> 3;1 --> 6)-beta-glucan from the micro fungus Epicoccum nigrum Ehrenb. ex Schlecht.

    PubMed

    Schmid, F; Stone, B A; McDougall, B M; Bacic, A; Martin, K L; Brownlee, R T; Chai, E; Seviour, R J

    2001-03-22

    The extracellular fungal polysaccharide, epiglucan, synthesised by Epicoccum nigrum is a side-chain/branched (1 --> 3;1 --> 6)-D-beta-glucan. Methylation analysis, 13C DEPT NMR and specific enzymic digestion data show slight variation in branching frequency among the epiglucans from the three strains examined. The (1 --> 3)-beta-linked backbone has (1 --> 6)-beta-linked branches at frequencies greater than the homologous glucans, scleroglucan and schizophyllan, from Sclerotium spp. and Schizophyllum commune, respectively. The structural analyses do not allow a distinction to be made between structures I and II. [structures: see text] Epiglucan displays non-Newtonian shear thinning rheological properties, typical of these glucans. PMID:11322730

  2. Structural characterization of saturated branched chain fatty acid methyl esters by collisional dissociation of molecular ions generated by electron ionization[S

    PubMed Central

    Ran-Ressler, Rinat R.; Lawrence, Peter; Brenna, J. Thomas

    2012-01-01

    Saturated branched chain fatty acids (BCFA) are present as complex mixtures in numerous biological samples. The traditional method for structure elucidation, electron ionization (EI) mass spectrometry, sometimes does not unambiguously enable assignment of branching in isomeric BCFA. Zirrolli and Murphy (Zirrolli , J. A. , and R. A. Murphy. 1993. Low-energy tandem mass spectrometry of the molecular ion derived from fatty acid methyl esters: a novel method for analysis of branched-chain fatty acids. J. Am. Soc. Mass Spectrom. 4: 223–229.) showed that the molecular ions of four BCFA methyl ester (BCFAME) yield highly characteristic fragments upon collisional dissociation using a triple quadrupole instrument. Here, we confirm and extend these results by analysis using a tabletop 3-D ion trap for activated molecular ion EI-MS/MS to 30 BCFAME. iso-BCFAME produces a prominent ion (30-100% of base peak) for [M-43] (M-C3H7), corresponding to the terminal isopropyl moiety in the original iso-BCFAME. Anteiso-FAME yield prominent ions (20-100% of base peak) corresponding to losses on both side of the methyl branch, [M-29] and [M-57], and tend to produce more prominent m/z 115 peaks corresponding to a cyclization product around the ester. Dimethyl and tetramethyl FAME, with branches separated by at least one methylene group, yield fragment on both sides of the sites of methyl branches that are more than 6 C away from the carboxyl carbon. EI-MS/MS yields uniquely specific ions that enable highly confident structural identification and quantification of BCFAME. PMID:22021637

  3. Characterization of the formation of branched short-chain fatty acid:CoAs for bitter acid biosynthesis in hop glandular trichomes.

    PubMed

    Xu, Haiyang; Zhang, Fengxia; Liu, Baoxiu; Huhman, David V; Sumner, Lloyd W; Dixon, Richard A; Wang, Guodong

    2013-07-01

    Bitter acids, known for their use as beer flavoring and for their diverse biological activities, are predominantly formed in hop (Humulus lupulus) glandular trichomes. Branched short-chain acyl-CoAs (e.g. isobutyryl-CoA, isovaleryl-CoA and 2-methylbutyryl-CoA), derived from the degradation of branched-chain amino acids (BCAAs), are essential building blocks for the biosynthesis of bitter acids in hops. However, little is known regarding what components are needed to produce and maintain the pool of branched short-chain acyl-CoAs in hop trichomes. Here, we present several lines of evidence that both CoA ligases and thioesterases are likely involved in bitter acid biosynthesis. Recombinant HlCCL2 (carboxyl CoA ligase) protein had high specific activity for isovaleric acid as a substrate (K cat /K m = 4100 s(-1) M(-1)), whereas recombinant HlCCL4 specifically utilized isobutyric acid (Kcat/K m = 1800 s(-1) M(-1)) and 2-methylbutyric acid (Kcat/K m = 6900 s(-1) M(-1)) as substrates. Both HlCCLs, like hop valerophenone synthase (HlVPS), were expressed strongly in glandular trichomes and localized to the cytoplasm. Co-expression of HlCCL2 and HlCCL4 with HlVPS in yeast led to significant production of acylphloroglucinols (the direct precursors for bitter acid biosynthesis), which further confirmed the biochemical function of these two HlCCLs in vivo. Functional identification of a thioesterase that catalyzed the reverse reaction of CCLs in mitochondria, together with the comprehensive analysis of genes involved BCAA catabolism, supported the idea that cytosolic CoA ligases are required for linking BCAA degradation and bitter acid biosynthesis in glandular trichomes. The evolution and other possible physiological roles of branched short-chain fatty acid:CoA ligases in planta are also discussed.

  4. The 1.9 A Structure of the Branched-Chain Amino-Acid Transaminase (IlvE) from Mycobacterium tuberculosis

    SciTech Connect

    Tremblay, L.; Blanchard, J

    2009-01-01

    Unlike mammals, bacteria encode enzymes that synthesize branched-chain amino acids. The pyridoxal 5'-phosphate-dependent transaminase performs the final biosynthetic step in these pathways, converting keto acid precursors into {alpha}-amino acids. The branched-chain amino-acid transaminase from Mycobacterium tuberculosis (MtIlvE) has been crystallized and its structure has been solved at 1.9 {angstrom} resolution. The MtIlvE monomer is composed of two domains that interact to form the active site. The biologically active form of IlvE is a homodimer in which each monomer contributes a substrate-specificity loop to the partner molecule. Additional substrate selectivity may be imparted by a conserved N-terminal Phe30 residue, which has previously been observed to shield the active site in the type IV fold homodimer. The active site of MtIlvE contains density corresponding to bound PMP, which is likely to be a consequence of the presence of tryptone in the crystallization medium. Additionally, two cysteine residues are positioned at the dimer interface for disulfide-bond formation under oxidative conditions. It is unknown whether they are involved in any regulatory activities analogous to those of the human mitochondrial branched-chain amino-acid transaminase.

  5. Arabidopsis and Maize RidA Proteins Preempt Reactive Enamine/Imine Damage to Branched-Chain Amino Acid Biosynthesis in Plastids[C][W][OPEN

    PubMed Central

    Niehaus, Thomas D.; Nguyen, Thuy N.D.; Gidda, Satinder K.; ElBadawi-Sidhu, Mona; Lambrecht, Jennifer A.; McCarty, Donald R.; Downs, Diana M.; Cooper, Arthur J.L.; Fiehn, Oliver; Mullen, Robert T.; Hanson, Andrew D.

    2014-01-01

    RidA (for Reactive Intermediate Deaminase A) proteins are ubiquitous, yet their function in eukaryotes is unclear. It is known that deleting Salmonella enterica ridA causes Ser sensitivity and that S. enterica RidA and its homologs from other organisms hydrolyze the enamine/imine intermediates that Thr dehydratase forms from Ser or Thr. In S. enterica, the Ser-derived enamine/imine inactivates a branched-chain aminotransferase; RidA prevents this damage. Arabidopsis thaliana and maize (Zea mays) have a RidA homolog that is predicted to be plastidial. Expression of either homolog complemented the Ser sensitivity of the S. enterica ridA mutant. The purified proteins hydrolyzed the enamines/imines formed by Thr dehydratase from Ser or Thr and protected the Arabidopsis plastidial branched-chain aminotransferase BCAT3 from inactivation by the Ser-derived enamine/imine. In vitro chloroplast import assays and in vivo localization of green fluorescent protein fusions showed that Arabidopsis RidA and Thr dehydratase are chloroplast targeted. Disrupting Arabidopsis RidA reduced root growth and raised the root and shoot levels of the branched-chain amino acid biosynthesis intermediate 2-oxobutanoate; Ser treatment exacerbated these effects in roots. Supplying Ile reversed the root growth defect. These results indicate that plastidial RidA proteins can preempt damage to BCAT3 and Ile biosynthesis by hydrolyzing the Ser-derived enamine/imine product of Thr dehydratase. PMID:25070638

  6. Arabidopsis and maize RidA proteins preempt reactive enamine/imine damage to branched-chain amino acid biosynthesis in plastids.

    PubMed

    Niehaus, Thomas D; Nguyen, Thuy N D; Gidda, Satinder K; ElBadawi-Sidhu, Mona; Lambrecht, Jennifer A; McCarty, Donald R; Downs, Diana M; Cooper, Arthur J L; Fiehn, Oliver; Mullen, Robert T; Hanson, Andrew D

    2014-07-01

    RidA (for Reactive Intermediate Deaminase A) proteins are ubiquitous, yet their function in eukaryotes is unclear. It is known that deleting Salmonella enterica ridA causes Ser sensitivity and that S. enterica RidA and its homologs from other organisms hydrolyze the enamine/imine intermediates that Thr dehydratase forms from Ser or Thr. In S. enterica, the Ser-derived enamine/imine inactivates a branched-chain aminotransferase; RidA prevents this damage. Arabidopsis thaliana and maize (Zea mays) have a RidA homolog that is predicted to be plastidial. Expression of either homolog complemented the Ser sensitivity of the S. enterica ridA mutant. The purified proteins hydrolyzed the enamines/imines formed by Thr dehydratase from Ser or Thr and protected the Arabidopsis plastidial branched-chain aminotransferase BCAT3 from inactivation by the Ser-derived enamine/imine. In vitro chloroplast import assays and in vivo localization of green fluorescent protein fusions showed that Arabidopsis RidA and Thr dehydratase are chloroplast targeted. Disrupting Arabidopsis RidA reduced root growth and raised the root and shoot levels of the branched-chain amino acid biosynthesis intermediate 2-oxobutanoate; Ser treatment exacerbated these effects in roots. Supplying Ile reversed the root growth defect. These results indicate that plastidial RidA proteins can preempt damage to BCAT3 and Ile biosynthesis by hydrolyzing the Ser-derived enamine/imine product of Thr dehydratase.

  7. An Efficient Independence Sampler for Updating Branches in Bayesian Markov chain Monte Carlo Sampling of Phylogenetic Trees.

    PubMed

    Aberer, Andre J; Stamatakis, Alexandros; Ronquist, Fredrik

    2016-01-01

    Sampling tree space is the most challenging aspect of Bayesian phylogenetic inference. The sheer number of alternative topologies is problematic by itself. In addition, the complex dependency between branch lengths and topology increases the difficulty of moving efficiently among topologies. Current tree proposals are fast but sample new trees using primitive transformations or re-mappings of old branch lengths. This reduces acceptance rates and presumably slows down convergence and mixing. Here, we explore branch proposals that do not rely on old branch lengths but instead are based on approximations of the conditional posterior. Using a diverse set of empirical data sets, we show that most conditional branch posteriors can be accurately approximated via a [Formula: see text] distribution. We empirically determine the relationship between the logarithmic conditional posterior density, its derivatives, and the characteristics of the branch posterior. We use these relationships to derive an independence sampler for proposing branches with an acceptance ratio of ~90% on most data sets. This proposal samples branches between 2× and 3× more efficiently than traditional proposals with respect to the effective sample size per unit of runtime. We also compare the performance of standard topology proposals with hybrid proposals that use the new independence sampler to update those branches that are most affected by the topological change. Our results show that hybrid proposals can sometimes noticeably decrease the number of generations necessary for topological convergence. Inconsistent performance gains indicate that branch updates are not the limiting factor in improving topological convergence for the currently employed set of proposals. However, our independence sampler might be essential for the construction of novel tree proposals that apply more radical topology changes. PMID:26231183

  8. Improving the cold flow properties of biodiesel by skeletal isomerization of fatty acid chains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodiesel is defined as the mono-alkyl fatty acid esters made from vegetable oil or animal fat lipids. Despite its many advantages, biodiesel from most lipid feedstocks has generally poor cold flow properties. The present study evaluates the fuel related properties of branched-chain fatty acid methy...

  9. Alkyl substitution effect: A high mobility bistetracene derivatives

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoyan; Liu, Yujuan; Zheng, Yujun

    2016-03-01

    Tetracenes and their derivatives are widely used in organic semiconductors for the advantages of small reorganization energies and large electronic couplings. The influences of long alkyl chain on charge transfer mobility of two bistetracene derivatives are investigated theoretically. The results show that the introduction of long alkyl chains would lead to a more compact packing, and increase electronic coupling, but reduce intermolecular distance. However, the introduction of long alkyl chains has little influence on reorganization energy. This provides a new understanding of the introduction of long alkyl chain on designing new high efficiency organic semiconductors.

  10. Postruminal synthesis modifies the odd- and branched-chain fatty acid profile from the duodenum to milk.

    PubMed

    Vlaeminck, B; Gervais, R; Rahman, M M; Gadeyne, F; Gorniak, M; Doreau, M; Fievez, V

    2015-07-01

    Milk odd- and branched-chain fatty acids (OBCFA) have been suggested as potential biomarkers for rumen function. The potential of milk OBCFA as a biomarker depends on whether their profile reflects the profile observed in the duodenum. The objective of this study was to evaluate whether the OBCFA profile in duodenum samples is reflected in plasma and milk. For this, 2 dairy cattle experiments were used. In experiment 1, 4 Holstein cows fitted with rumen and proximal duodenum cannulas were used in a 4×4 Latin square design. The treatments consisted of 2 nitrogen levels (143 vs. 110g of crude protein/kg of dry matter for high and low N, respectively) combined with either 1 of the 2 energy sources (i.e., starch from barley, corn, and wheat or fiber from soybean hulls and dehydrated beet pulp). In experiment 2, 4 Holstein cows fitted with rumen and proximal duodenum cannulas were used in a 3×3 Latin square design, with the treatments consisting of 3 diets: (1) RNB-, a diet with a crude protein content of 122g/kg of dry matter, predicted to provide protein digested in the small intestine according to the requirement of the animals, but with a shortage of rumen degradable protein; (2) RNB- to which 6g/d of niacin was added through inclusion in the mineral and vitamin premix, and (3) RNB- to which urea was added to balance rumen degradable N supply resulting in a CP content of 156g/kg of dry matter. In both experiments, samples of duodenal digesta, plasma, and milk were collected and analyzed for fatty acids. Additionally, lipids in plasma samples were separated in lipid classes and analyzed for fatty acids. The OBCFA profile in milk was enriched in 15:0, iso-17:0, anteiso-17:0, and cis-9-17:1 as compared with duodenal samples, and milk secretions even exceeded duodenal flows, which suggests occurrence of postruminal synthesis, such as de novo synthesis, desaturation, and elongation. The postruminal modification of the OBCFA profile might hamper the application of OBCFA

  11. A 7-day oral supplementation with branched-chain amino acids was ineffective to prevent muscle damage during a marathon.

    PubMed

    Areces, Francisco; Salinero, Juan Jose; Abian-Vicen, Javier; González-Millán, Cristina; Gallo-Salazar, Cesar; Ruiz-Vicente, Diana; Lara, Beatriz; Del Coso, Juan

    2014-05-01

    The aim of this study was to determine the effectiveness of a 7-day oral supplementation with branched-chain amino acids (BCAA) to prevent muscle damage during a marathon. Forty-six experienced runners were randomly divided into two groups, one with BCAA supplementation (n = 25, supplemented with 5 g day(-1) of powdered 1:0.5:0.5 leucine:isoleucine:valine, during the 7 days prior to the competition) and the other as a control group (n = 21, supplemented with an isocaloric placebo). Before the marathon race and within 3 min of finishing, leg muscle power was measured with a maximal countermovement jump and a urine sample was obtained. During the race, running pace was measured by means of a time-chip. Myoglobin concentration was determined in the urine samples as an indirect marker of muscle damage. A visual analog scale (0-10 points) was used to assess leg muscle pain during the race. In the BCAA group, the mean running pace during the marathon was similar to the control group (3.3 ± 0.4 vs. 3.3 ± 0.5 m s(-1), respectively, 0.98). The pre- to post-race reduction in muscle power was similar in both BCAA and control groups (-23.0 ± 16.1 vs. -17.3 ± 13.8 %, P = 0.13). Post-race urine myoglobin concentration was similar in both BCAA and control groups (5.4 ± 7.5 vs. 4.5 ± 8.6 μg mL(-1), P = 0.70). Finally, there were no differences between groups in the perceived muscle pain during the race (6 ± 1 vs. 5 ± 1 points, P = 0.80). A 7-day supplementation of BCAA (5 g day(-1)) did not increase the running performance during a marathon. Furthermore, BCAA supplementation was ineffective to prevent muscle power loss, muscle damage or perceived muscle pain during a marathon race. PMID:24477835

  12. A 7-day oral supplementation with branched-chain amino acids was ineffective to prevent muscle damage during a marathon.

    PubMed

    Areces, Francisco; Salinero, Juan Jose; Abian-Vicen, Javier; González-Millán, Cristina; Gallo-Salazar, Cesar; Ruiz-Vicente, Diana; Lara, Beatriz; Del Coso, Juan

    2014-05-01

    The aim of this study was to determine the effectiveness of a 7-day oral supplementation with branched-chain amino acids (BCAA) to prevent muscle damage during a marathon. Forty-six experienced runners were randomly divided into two groups, one with BCAA supplementation (n = 25, supplemented with 5 g day(-1) of powdered 1:0.5:0.5 leucine:isoleucine:valine, during the 7 days prior to the competition) and the other as a control group (n = 21, supplemented with an isocaloric placebo). Before the marathon race and within 3 min of finishing, leg muscle power was measured with a maximal countermovement jump and a urine sample was obtained. During the race, running pace was measured by means of a time-chip. Myoglobin concentration was determined in the urine samples as an indirect marker of muscle damage. A visual analog scale (0-10 points) was used to assess leg muscle pain during the race. In the BCAA group, the mean running pace during the marathon was similar to the control group (3.3 ± 0.4 vs. 3.3 ± 0.5 m s(-1), respectively, 0.98). The pre- to post-race reduction in muscle power was similar in both BCAA and control groups (-23.0 ± 16.1 vs. -17.3 ± 13.8 %, P = 0.13). Post-race urine myoglobin concentration was similar in both BCAA and control groups (5.4 ± 7.5 vs. 4.5 ± 8.6 μg mL(-1), P = 0.70). Finally, there were no differences between groups in the perceived muscle pain during the race (6 ± 1 vs. 5 ± 1 points, P = 0.80). A 7-day supplementation of BCAA (5 g day(-1)) did not increase the running performance during a marathon. Furthermore, BCAA supplementation was ineffective to prevent muscle power loss, muscle damage or perceived muscle pain during a marathon race.

  13. Intermediaries of branched chain amino acid metabolism induce fetal hemoglobin, and repress SOX6 and BCL11A, in definitive erythroid cells.

    PubMed

    Karkashon, Shay; Raghupathy, Radha; Bhatia, Himanshu; Dutta, Amrita; Hess, Sonja; Higgs, Jaimie; Tifft, Cynthia J; Little, Jane A

    2015-08-01

    High levels of fetal hemoglobin (HbF) can ameliorate human β-globin gene disorders. The short chain fatty acid butyrate is the paradigmatic metabolic intermediary that induces HbF. Inherited disorders of branched-chain amino acid (BCAA) metabolism have been associated with supranormal HbF levels beyond infancy, e.g., propionic acidemia (PA) and methylmalonic acidemia (MMA). We tested intermediaries of BCAA metabolism for their effects on definitive erythropoiesis. Like butyrate, the elevated BCAA intermediaries isovalerate, isobutyrate, and propionate, induce fetal globin gene expression in murine EryD in vitro, are associated with bulk histone H3 hyperacylation, and repress the transcription of key gamma globin regulatory factors, notably BCL11A and SOX6. Metabolic intermediaries that are elevated in Maple Syrup Urine Disease (MSUD) affect none of these processes. Percent HbF and gamma (γ) chain isoforms were also measured in non-anemic, therapeutically optimized subjects with MSUD (Group I, n=6) or with Isovaleric Acidemia (IVA), MMA, or PA (Group II, n=5). Mean HbF was 0.24 ± 0.15% in Group I and 0.87 ± 0.13% in Group II (p=.01); only the Gγ isoform was detected. We conclude that a family of biochemically related intermediaries of branched chain amino acid metabolism induces fetal hemoglobin during definitive erythropoiesis, with mechanisms that mirror those so far identified for butyrate. PMID:26142333

  14. Single chain morphology and nanofiber-like aggregates of branched β-(1 → 3)-D-glucan in water/dimethylsulfoxide solution.

    PubMed

    Chen, Cong; Meng, Yan; Li, Sheng; Wu, Wenhua; Liu, Chuanjun; Xu, Xiaojuan; Zhang, Lina

    2016-02-10

    A polysaccharide coded as PR-CA was extracted from Polyporus rhinoceros and determined to be a β-(1 → 3)-D-glucan with multiple branches. The weight-average molecular weights (Mw) of PR-CA in dimethylsulfoxide (DMSO) and in water were determined with static light scattering (SLS) to be 3.57 × 10(5) and 1.79 × 10(7), indicating existence of the single chains in DMSO and co-existence of single chains and aggregates in water. Moreover, the stiffness of single chains of PR-CA in water was directly visualized by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The hollow structure of PR-CA nanofibers with width of 30-40 nm and length of ∼ 350 nm formed in the water/DMSO (9:1, v:v) was demonstrated by a fluorescent probe tetraphenylethylene (TPE) via aggregation-induced emission (AIE). The formation of PR-CA nanofibers was ascribed to the parallel aggregation of the extended PR-CA chains due to the hydrogen bonding and hydrophobic interaction. This work offered valuable results for promising applications of natural branched β-glucans in the biological fields of drug inclusion, delivery and disease diagnosis. PMID:26686132

  15. Rapid determination of four short-chain alkyl mercapturic acids in human urine by column-switching liquid chromatography-tandem mass spectrometry.

    PubMed

    Eckert, Elisabeth; Göen, Thomas

    2014-08-15

    We developed and validated an analytical method for the simultaneous determination of methyl mercapturic acid (MeMA), ethyl mercapturic acid (EtMA), n-propyl mercapturic acid (PrMA) and iso-propyl mercapturic acid (iPrMA) in human urine. These alkyl mercapturic acids are known or presumed biomarkers of exposure to several alkylating agents including methyl bromide, dimethyl sulfate, ethyl bromide, 1-bromopropane and 2-bromopropane. The method involves a column switching arrangement for online solid phase extraction of the analytes with subsequent analytical separation and detection using liquid chromatography and tandem mass spectrometry. Within day and day-to-day imprecision was determined to range from 4.5 to 12.2%. The analytical method is distinguished by its wide linear working range of up to 2,500 μg/L with detection limits ranging from 2.0 μg/L (for PrMA) to 5.1 μg/L (for MeMA) that render possible the application in various biomonitoring studies regarding exposure to alkylating agents. The results of a pilot study on urine samples of 30 individuals occupationally non-exposed to alkylating agents using the new procedure confirmed the background excretion of MeMA (<5.1-35.6 μg/L) and PrMA (<2.0-95.7 μg/L).

  16. Effect of cation asymmetry on the aggregation in aqueous 1-alkyl,3-decylimidazolium bromide solutions: molecular dynamics studies.

    PubMed

    Palchowdhury, Sourav; Bhargava, B L

    2014-06-12

    Self-assembly of cations in aqueous solutions of 1-alkyl,3-decylimidazolium bromide (with four different alkyl chains, methyl, butyl, heptyl, and decyl chain,) have been studied using atomistic molecular dynamics simulations. Polydisperse aggregates of cations are formed in the solution with alkyl tails in the core and the polar head groups present at the surface of the aggregates. The shape of the aggregates is dictated by the length of the alkyl chain. Aggregation numbers increase steadily with the increasing alkyl chain length. The greater asymmetry in the two-substituent chain length leads to a different surface structure compared to that of the cations with alkyl chains of similar length.

  17. Determination of rate constants and branching ratios for TCE degradation by zero-valent iron using a chain decay multispecies model

    NASA Astrophysics Data System (ADS)

    Hwang, Hyoun-Tae; Jeen, Sung-Wook; Sudicky, Edward A.; Illman, Walter A.

    2015-06-01

    The applicability of a newly-developed chain-decay multispecies model (CMM) was validated by obtaining kinetic rate constants and branching ratios along the reaction pathways of trichloroethene (TCE) reduction by zero-valent iron (ZVI) from column experiments. Changes in rate constants and branching ratios for individual reactions for degradation products over time for two columns under different geochemical conditions were examined to provide ranges of those parameters expected over the long-term. As compared to the column receiving deionized water, the column receiving dissolved CaCO3 showed higher mean degradation rates for TCE and all of its degradation products. However, the column experienced faster reactivity loss toward TCE degradation due to precipitation of secondary carbonate minerals, as indicated by a higher value for the ratio of maximum to minimum TCE degradation rate observed over time. From the calculated branching ratios, it was found that TCE and cis-dichloroethene (cis-DCE) were dominantly dechlorinated to chloroacetylene and acetylene, respectively, through reductive elimination for both columns. The CMM model, validated by the column test data in this study, provides a convenient tool to determine simultaneously the critical design parameters for permeable reactive barriers and natural attenuation such as rate constants and branching ratios.

  18. Effects of Alkyl Chain Length and Hydrogen Bonds on the Cooperative Self-Assembly of 2-Thienyl-Type Diarylethenes at a Liquid/Highly Oriented Pyrolytic Graphite (HOPG) Interface.

    PubMed

    Yokoyama, Soichi; Hirose, Takashi; Matsuda, Kenji

    2015-09-21

    An appropriate understanding of the process of self-assembly is of critical importance to tailor nanostructured order on 2D surfaces with functional molecules. Photochromic compounds are promising candidates for building blocks of advanced photoresponsive surfaces. To investigate the relationship between molecular structure and the mechanism of ordering formation, 2-thienyl-type diarylethenes with various lengths of alkyl side chains linked through an amide or ester group were synthesized. Their self-assemblies at a liquid/solid interface were investigated by scanning tunneling microscopy (STM). The concentration dependence of the surface coverage was analyzed by using a cooperative model for a 2D surface based on two characteristic parameters: the nucleation equilibrium constant (Kn) and the elongation equilibrium constant (Ke). The following conclusions can be drawn. 1) The concentration at which a stable 2D molecular ordering is observed by STM exponentially decreases with increasing length of the alkyl chain. 2) Compounds bearing amide groups have higher degrees of cooperativity in self-assembly on 2D surfaces (i.e., σ, which is defined as Kn/Ke) than compounds with ester groups. 3) The self-assembly process of the open-ring isomer of an ester derivative is close to isodesmic, whereas that of the closed-ring isomer is cooperative because of the difference in equilibrium constants for the nucleation step (i.e., Kn) between the two isomers.

  19. Xanthomonas campestris FabH is required for branched-chain fatty acid and DSF-family quorum sensing signal biosynthesis.

    PubMed

    Yu, Yong-Hong; Hu, Zhe; Dong, Hui-Juan; Ma, Jin-Cheng; Wang, Hai-Hong

    2016-01-01

    Xanthomonas campestris pv. campestris (Xcc), a Gram-negative phytopathogenic bacterium, causes black rot disease of cruciferous vegetables. Although Xcc has a complex fatty acid profile comprised of straight-chain fatty acids and branched-chain fatty acids (BCFAs), and encodes a complete set of genes required for fatty acid synthesis, there is still little known about the mechanism of BCFA synthesis. We reported that expression of Xcc fabH restores the growth of Ralstonia solanacearum fabH mutant, and this allows the R. solanacearum fabH mutant to produce BCFAs. Using in vitro assays, we demonstrated that Xcc FabH is able to condense branched-chain acyl-CoAs with malonyl-ACP to initiate BCFA synthesis. Moreover, although the fabH gene is essential for growth of Xcc, it can be replaced with Escherichia coli fabH, and Xcc mutants failed to produce BCFAs. These results suggest that Xcc does not have an obligatory requirement for BCFAs. Furthermore, Xcc mutants lost the ability to produce cis-11-methyl-2-dodecenoic acid, a diffusible signal factor (DSF) required for quorum sensing of Xcc, which confirms that the fatty acid synthetic pathway supplies the intermediates for DSF signal biosynthesis. Our study also showed that replacing Xcc fabH with E. coli fabH affected Xcc pathogenesis in host plants. PMID:27595587

  20. Xanthomonas campestris FabH is required for branched-chain fatty acid and DSF-family quorum sensing signal biosynthesis

    PubMed Central

    Yu, Yong-Hong; Hu, Zhe; Dong, Hui-Juan; Ma, Jin-Cheng; Wang, Hai-Hong

    2016-01-01

    Xanthomonas campestris pv. campestris (Xcc), a Gram-negative phytopathogenic bacterium, causes black rot disease of cruciferous vegetables. Although Xcc has a complex fatty acid profile comprised of straight-chain fatty acids and branched-chain fatty acids (BCFAs), and encodes a complete set of genes required for fatty acid synthesis, there is still little known about the mechanism of BCFA synthesis. We reported that expression of Xcc fabH restores the growth of Ralstonia solanacearum fabH mutant, and this allows the R. solanacearum fabH mutant to produce BCFAs. Using in vitro assays, we demonstrated that Xcc FabH is able to condense branched-chain acyl-CoAs with malonyl-ACP to initiate BCFA synthesis. Moreover, although the fabH gene is essential for growth of Xcc, it can be replaced with Escherichia coli fabH, and Xcc mutants failed to produce BCFAs. These results suggest that Xcc does not have an obligatory requirement for BCFAs. Furthermore, Xcc mutants lost the ability to produce cis-11-methyl-2-dodecenoic acid, a diffusible signal factor (DSF) required for quorum sensing of Xcc, which confirms that the fatty acid synthetic pathway supplies the intermediates for DSF signal biosynthesis. Our study also showed that replacing Xcc fabH with E. coli fabH affected Xcc pathogenesis in host plants. PMID:27595587

  1. Swallow-tailed alkyl and linear alkoxy-substituted dibenzocoronene tetracarboxdiimide derivatives: synthesis, photophysical properties, and thermotropic behaviors.

    PubMed

    Yang, Tengzhou; Pu, Jialing; Zhang, Jun; Wang, Wenguang

    2013-05-17

    A series of dibenzocoronene tetracarboxdiimide derivatives decorated with alkyl swallow-tail and alkoxy moieties were synthesized, and their structures were characterized. 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an effective oxidant was first used in the benzannulation of perylene diimides with the almost quantitative yield. The thermotropic behavior was investigated using differential scanning calorimetry (DSC) and polarization optical microscopy (POM). The introduction of alkyl swallow-tail and alkoxy substituents facilitates thermotropic liquid crystalline behavior. The branching site of alkyl swallow-tail units at the α position and the longer alkoxy chains played a similar role in lowering the mesophase transition as well as isotropization transition temperatures. The UV-vis absorption spectra of all compounds appeared as absorption in 425-600 nm region, and POM images of certain compounds exhibited characteristic columnar hexagonal (Col(h)) packing and readily self-assembled into a homeotropic alignment toward the substrate. PMID:23600443

  2. Analytic study of the chain dark decomposition reaction of iodides - atomic iodine donors - in the active medium of a pulsed chemical oxygen-iodine laser: 1. Criteria for the development of the branching chain dark decomposition reaction of iodides

    SciTech Connect

    Andreeva, Tamara L; Kuznetsova, S V; Maslov, Aleksandr I; Sorokin, Vadim N

    2009-02-28

    The scheme of chemical processes proceeding in the active medium of a pulsed chemical oxygen-iodine laser (COIL) is analysed. Based on the analysis performed, the complete system of differential equations corresponding to this scheme is replaced by a simplified system of equations describing in dimensionless variables the chain dark decomposition of iodides - atomic iodine donors, in the COIL active medium. The procedure solving this system is described, the basic parameters determining the development of the chain reaction are found and its specific time intervals are determined. The initial stage of the reaction is analysed and criteria for the development of the branching chain decomposition reaction of iodide in the COIL active medium are determined. (active media)

  3. Direct determination of flavor relevant and further branched-chain fatty acids from sheep subcutaneous adipose tissue by gas chromatography with mass spectrometry.

    PubMed

    Kaffarnik, Stefanie; Preuß, Siegfried; Vetter, Walter

    2014-07-11

    4-Methyloctanoic acid, 4-ethyloctanoic acid and 4-methylnonanoic acid are key-flavor compounds of sheep and goat. Yet, the low amounts of these volatile branched-chain fatty acids (vBCFAs) in the fat of the ruminants hampered their determination on a routine basis. In this work we developed a gas chromatography/mass spectrometry selected ion monitoring (GC/MS-SIM) method for the direct determination of the vBCFAs as methyl esters, which were obtained after transesterification of subcutaneous adipose tissue of sheep. The excellent sensitivity of the GC/MS-SIM method (limit of quantification, LOQ, 3.6-4.8μg/g; limit of detection, LOD, 1.1-1.4μg/g for 4-Me-8:0, 4-Et-8:0 and 4-Me-9:0) enabled us to determine the three vBCFAs without an enrichment step. Subcutaneous adipose sheep tissue of three different breeds contained 23-88μg/g 4-methyloctanoic acid, 13-26μg/g 4-ethyloctanoic acid and ∼2.9-18μg/g 4-methylnonanoic acid. Since all fatty acids were present in the FAME fraction, the samples could be screened for further branched-chain FAMEs. After elimination of unsaturated fatty acids by hydrogenation (the presence of some unsaturated fatty acids could be verified by this measure), additional measurements in SIM and full scan modes of methyl esters and picolinyl esters enabled the determination of further 97 saturated fatty acids in the samples with eight to 20 carbons. The method is suited for routine analysis and may be useful to investigate the reasons for the abundance/absence of 4-methyloctanoic acid, 4-ethyloctanoic acid and 4-methylnonanoic acid and further branched-chain fatty acids in sheep and goat.

  4. Functional roles of a predicted branched chain aminotransferase encoded by the LkBAT1 gene of the yeast Lachancea kluyveri.

    PubMed

    Montalvo-Arredondo, Javier; Jiménez-Benítez, Ángel; Colón-González, Maritrini; González-Flores, James; Flores-Villegas, Mirelle; González, Alicia; Riego-Ruiz, Lina

    2015-12-01

    Branched chain amino acid aminotransferases (BCATs) catalyze the last step of the biosynthesis and the first step of the catabolism of branched chain amino acids. In Saccharomyces cerevisiae, BCATs are encoded by the ScBAT1 and ScBAT2 paralogous genes. Analysis of Lachancea kluyveri genome sequence, allowed the identification of the LkBAT1 locus, which could presumably encode a BCAT. A second unlinked locus (LkBAT1bis), exhibiting sequence similarity to LkBAT1 was also identified. To determine the function of these putative BCATs, L. kluyveri mutant strains lacking LkBAT1, LkBAT1bis or both genes were generated and tested for VIL metabolism. LkBat1 displayed branched chain aminotransferase activity and is required for VIL biosynthesis and catabolism. However, Lkbat1Δ mutant is a valine and isoleucine auxotroph and a leucine bradytroph indicating that L. kluyveri harbors an alternative enzyme(s) involved in leucine biosynthesis. Additionally, heterologous reciprocal gene complementation between S. cerevisiae and L. kluyveri orthologous LkBAT1, ScBAT1 and ScBAT2 genes, confirmed that the mitochondrial LkBat1 functions as BCAT in S. cerevisiae, restoring wild type phenotype to the ScBAT1 null mutant. Conversely, LkBAT1bis did not display a role in BCAAs metabolism. However, when ethanol was used as carbon source, deletion of LkBAT1bis in an Lkbat1Δ null strain resulted in an extended 'lag' growth phase, pointing to a potential function of LkBAT1 and LkBAT1bis in the aerobic metabolism of L. kluyveri. These results confirm the BCAT function of LkBAT1 in L. kluyveri, and further support the proposition that the BCAT function in ancestral-type yeasts has been distributed in the two paralogous genes present in S. cerevisiae.

  5. Effect of diet and starvation on the activity state of branched-chain 2-oxo-acid dehydrogenase complex in rat liver and heart.

    PubMed

    Solomon, M; Cook, K G; Yeaman, S J

    1987-12-10

    In rats fed a high-protein diet, the branched-chain 2-oxo-acid dehydrogenase complex in liver was essentially fully active and its activity state was unaffected by subsequent starvation for 48 h. Feeding with a low-protein diet led to a decrease in the activity state which was essentially reversed by 48 h of starvation. In heart, the enzyme was primarily inactive (activity state 18%) in rats fed a high-protein diet, with both low-protein diet and starvation leading to a further decrease in the activity state. PMID:3676350

  6. Direct RNA detection without nucleic acid purification and PCR: Combining sandwich hybridization with signal amplification based on branched hybridization chain reaction.

    PubMed

    Xu, Yao; Zheng, Zhi

    2016-05-15

    We have developed a convenient, robust and low-cost RNA detection system suitable for high-throughput applications. This system uses a highly specific sandwich hybridization to capture target RNA directly onto solid support, followed by on-site signal amplification via 2-dimensional, branched hybridizing chain polymerization through toehold-mediated strand displacement reaction. The assay uses SYBR Green to detect targets at concentrations as low as 1 pM, without involving nucleic acid purification or any enzymatic reaction, using ordinary oligonucleotides without modification or labeling. The system was demonstrated in the detection of malaria RNA in blood and GAPDH gene expression in cell lysate.

  7. Functional role of residue 193 (chymotrypsin numbering) in serine proteases: influence of side chain length and beta-branching on the catalytic activity of blood coagulation factor XIa.

    PubMed

    Schmidt, Amy E; Sun, Mao-fu; Ogawa, Taketoshi; Bajaj, S Paul; Gailani, David

    2008-02-01

    In serine proteases, Gly193 (chymotrypsin numbering) is conserved with rare exception. Mutants of blood coagulation proteases have been reported with Glu, Ala, Arg or Val substitutions for Gly193. To further understand the role of Gly193 in protease activity, we replaced it with Ala or Val in coagulation factor XIa (FXIa). For comparison to the reported FXIa Glu193 mutant, we prepared FXIa with Asp (short side chain) or Lys (opposite charge) substitutions. Binding of p-aminobenzamidine (pAB) and diisopropylfluorphosphate (DFP) were impaired 1.6-36-fold and 35-478-fold, respectively, indicating distortion of, or altered accessibility to, the S1 and oxyanion-binding sites. Val or Asp substitutions caused the most impairment. Salt bridge formation between the amino terminus of the mature protease moiety at Ile16 and Asp194, essential for catalysis, was impaired 1.4-4-fold. Mutations reduced catalytic efficiency of tripeptide substrate hydrolysis 6-280-fold, with Val or Asp causing the most impairment. Further studies were directed toward macromolecular interactions with the FXIa mutants. kcat for factor IX activation was reduced 8-fold for Ala and 400-1100-fold for other mutants, while binding of the inhibitors antithrombin and amyloid beta-precursor protein Kunitz domain (APPI) was impaired 13-2300-fold and 22-27000-fold, respectively. The data indicate that beta-branching of the side chain of residue 193 is deleterious for interactions with pAB, DFP and amidolytic substrates, situations where no S2'-P2' interactions are involved. When an S2'-P2' interaction is involved (factor IX, antithrombin, APPI), beta-branching and increased side chain length are detrimental. Molecular models indicate that the mutants have impaired S2' binding sites and that beta-branching causes steric conflicts with the FXIa 140-loop, which could perturb the local tertiary structure of the protease domain. In conclusion, enzyme activity is impaired in FXIa when Gly193 is replaced by a non

  8. Low half-wave voltage Y-branch electro-optic polymer modulator based on side-chain polyurethane-imide

    NASA Astrophysics Data System (ADS)

    Tang, Jie; Wang, Long-De; Li, Ruo-Zhou; Zhang, Qiang; Zhang, Tong

    2016-06-01

    A Y-branch electro-optic (EO) polymer modulator has been designed and fabricated. High performance side-chain polyurethane-imide (PUI) with a high EO coefficient of larger than 50 pm/V and a moderate glass-transition temperature (Tg) of 206∘C is used as EO polymer core layer of the modulator. The fabricated phase modulator exhibits a low half-wave voltage of 1.94 V at 1550 nm in single arm modulation with 1 cm EO interaction length and 2 cm total length. The results show that the modulator fabricated by side-chain PUI EO materials possesses potential applications in low driving voltage and low cost optical systems.

  9. Chronic administration of branched-chain amino acids impairs spatial memory and increases brain-derived neurotrophic factor in a rat model.

    PubMed

    Scaini, Giselli; Comim, Clarissa M; Oliveira, Giovanna M T; Pasquali, Matheus A B; Quevedo, João; Gelain, Daniel P; Moreira, José Cláudio F; Schuck, Patrícia F; Ferreira, Gustavo C; Bogo, Maurício R; Streck, Emilio L

    2013-09-01

    Maple syrup urine disease (MSUD) is a neurometabolic disorder that leads to the accumulation of branched-chain amino acids (BCAAs) and their α-keto branched-chain by-products. Because the neurotoxic mechanisms of MSUD are poorly understood, this study aimed to evaluate the effects of chronic administration of a BCAA pool (leucine, isoleucine and valine). This study examined the effects of BCAA administration on spatial memory and the levels of brain-derived neurotrophic factor (BNDF). We examined both pro-BDNF and bdnf mRNA expression levels after administration of BCAAs. Furthermore, this study examined whether antioxidant treatment prevented the alterations induced by BCAA administration. Our results demonstrated an increase in BDNF in the hippocampus and cerebral cortex, accompanied by memory impairment in spatial memory tasks. Additionally, chronic administration of BCAAs did not induce a detectable change in pro-BDNF levels. Treatment with N-acetylcysteine and deferoxamine prevented both the memory deficit and the increase in the BDNF levels induced by BCAA administration. In conclusion, these results suggest that when the brain is chronically exposed to high concentrations of BCAA (at millimolar concentrations) an increase in BDNF levels occurs. This increase in BDNF may be related to the impairment of spatial memory. In addition, we demonstrated that antioxidant treatment prevented the negative consequences related to BCAA administration, suggesting that oxidative stress might be involved in the pathophysiological mechanism(s) underlying the brain damage observed in MSUD. PMID:23109061

  10. The Feasibility of Assessing Branched-Chain Amino Acid Metabolism in Cellular Models of Prostate Cancer with Hyperpolarized [1-13C]-Ketoisocaproate

    PubMed Central

    Billingsley, Kelvin L.; Park, Jae Mo; Josan, Sonal; Hurd, Ralph; Mayer, Dirk; Spielman-Sun, Eleanor; Nishimura, Dwight G.; Brooks, James D.; Spielman, Daniel

    2014-01-01

    Recent advancements in the field of hyperpolarized 13C magnetic resonance spectroscopy (MRS) have yielded powerful techniques capable of real-time analysis of metabolic pathways. These non-invasive methods have increasingly shown application in impacting disease diagnosis and have further been employed in mechanistic studies of disease onset and progression. Our goals were to investigate branched-chain aminotransferase (BCAT) activity in prostate cancer with a novel molecular probe, hyperpolarized [1-13C]-2-ketoisocaproate ([1-13C]-KIC), and explore the potential of branched-chain amino acid (BCAA) metabolism to serve as a biomarker. Using traditional spectrophotometric assays, BCAT enzymatic activities were determined in vitro for various sources of prostate cancer (human, transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse and human cell lines). These preliminary studies indicated that low levels of BCAT activity were present in all models of prostate cancer but enzymatic levels are altered significantly in prostate cancer relative to healthy tissue. The MR spectroscopic studies were conducted with two cellular models (PC-3 and DU-145) that exhibited levels of BCAA metabolism comparable to the human disease state. Hyperpolarized [1-13C]-KIC was administered to prostate cancer cell lines, and the conversion of [1-13C]-KIC to the metabolic product, [1-13C]-leucine ([1-13C]-Leu), could be monitored via hyperpolarized 13C MRS. PMID:24907854

  11. Methoxy-derivatization of alkyl chains increases the in vivo efficacy of cationic Mn porphyrins. Synthesis, characterization, SOD-like activity, and SOD-deficient E. coli study of meta Mn(III) N-methoxyalkylpyridylporphyrins.

    PubMed

    Tovmasyan, Artak G; Rajic, Zrinka; Spasojevic, Ivan; Reboucas, Julio S; Chen, Xin; Salvemini, Daniela; Sheng, Huaxin; Warner, David S; Benov, Ludmil; Batinic-Haberle, Ines

    2011-04-28

    Cationic Mn(III) N-alkylpyridylporphyrins (MnPs) are potent SOD mimics and peroxynitrite scavengers and diminish oxidative stress in a variety of animal models of central nervous system (CNS) injuries, cancer, radiation, diabetes, etc. Recently, properties other than antioxidant potency, such as lipophilicity, size, shape, and bulkiness, which influence the bioavailability and the toxicity of MnPs, have been addressed as they affect their in vivo efficacy and therapeutic utility. Porphyrin bearing longer alkyl substituents at pyridyl ring, MnTnHex-2-PyP(5+), is more lipophilic, thus more efficacious in vivo, particularly in CNS injuries, than the shorter alkyl-chained analog, MnTE-2-PyP(5+). Its enhanced lipophilicity allows it to accumulate in mitochondria (relative to cytosol) and to cross the blood-brain barrier to a much higher extent than MnTE-2-PyP(5+). Mn(III) N-alkylpyridylporphyrins of longer alkyl chains, however, bear micellar character, and when used at higher levels, become toxic. Recently we showed that meta isomers are ∼10-fold more lipophilic than ortho species, which enhances their cellular accumulation, and thus reportedly compensates for their somewhat inferior SOD-like activity. Herein, we modified the alkyl chains of the lipophilic meta compound, MnTnHex-3-PyP(5+) via introduction of a methoxy group, to diminish its toxicity (and/or enhance its efficacy), while maintaining high SOD-like activity and lipophilicity. We compared the lipophilic Mn(III) meso-tetrakis(N-(6'-methoxyhexyl)pyridinium-3-yl)porphyrin, MnTMOHex-3-PyP(5+), to a hydrophilic Mn(III) meso-tetrakis(N-(2'-methoxyethyl)pyridinium-3-yl)porphyrin, MnTMOE-3-PyP(5+). The compounds were characterized by uv-vis spectroscopy, mass spectrometry, elemental analysis, electrochemistry, and ability to dismute O(2)˙(-). Also, the lipophilicity was characterized by thin-layer chromatographic retention factor, R(f). The SOD-like activities and metal-centered reduction potentials for the Mn

  12. Comparative metabolism of branched-chain amino acids to precursors of juvenile hormone biogenesis in corpora allata of lepidopterous versus nonlepidopterous insects

    SciTech Connect

    Brindle, P.A.; Schooley, D.A.; Tsai, L.W.; Baker, F.C.

    1988-08-05

    Comparative studies were performed on the role of branched-chain amino acids (BCAA) in juvenile hormone (JH) biosynthesis using several lepidopterous and nonlepidopterous insects. Corpora cardiaca-corpora allata complexes (CC-CA, the corpora allata being the organ of JH biogenesis) were maintained in culture medium containing a uniformly /sup 14/C-labeled BCAA, together with (methyl-/sup 3/H)methionine as mass marker for JH quantification. BCAA catabolism was quantified by directly analyzing the medium for the presence of /sup 14/C-labeled propionate and/or acetate, while JHs were extracted, purified by liquid chromatography, and subjected to double-label liquid scintillation counting. Our results indicate that active BCAA catabolism occurs within the CC-CA of lepidopterans, and this efficiently provides propionyl-CoA (from isoleucine or valine) for the biosynthesis of the ethyl branches of JH I and II. Acetyl-CoA, formed from isoleucine or leucine catabolism, is also utilized by lepidopteran CC-CA for biosynthesizing JH III and the acetate-derived portions of the ethyl-branched JHs. In contrast, CC-CA of nonlepidopterans fail to catabolize BCAA. Consequently, exogenous isoleucine or leucine does not serve as a carbon source for the biosynthesis of JH III by these glands, and no propionyl-CoA is produced for genesis of ethyl-branched JHs. This is the first observation of a tissue-specific metabolic difference which in part explains why these novel homosesquiterpenoids exist in lepidopterans, but not in nonlepidopterans.

  13. Shock tube measurements of growth constants in the branched-chain ethane-carbon monoxide-oxygen system

    NASA Technical Reports Server (NTRS)

    Brokaw, R. S.; Brabbs, T. A.; Snyder, C. A.

    1985-01-01

    Exponential free radical growth constants have been measured for ethane carbon monoxide oxygen mixtures by monitoring the growth of oxygen atom concentration as manifested by CO flame band emission. Data were obtained over the temperature range of 1200 to 1700 K. The data were analyzed using an ethane oxidation mechanism involving seven elementary reaction steps. Calculated growth constants were close to experimental values at lower temperatures, up to about 1400 K, but at higher temperatures computed growth constants were considerably smaller than experiment. In attempts to explain these results additional branching reactions were added to the mechanism. However, these additional reactions did not appreciably change calculated growth constants.

  14. Suppression of Aflatoxin Biosynthesis in Aspergillus flavus by 2-Phenylethanol Is Associated with Stimulated Growth and Decreased Degradation of Branched-Chain Amino Acids

    PubMed Central

    Chang, Perng-Kuang; Hua, Sui Sheng T.; Sarreal, Siov Bouy L.; Li, Robert W.

    2015-01-01

    The saprophytic soil fungus Aspergillus flavus infects crops and produces aflatoxin. Pichia anomala, which is a biocontrol yeast and produces the major volatile 2-phenylethanol (2-PE), is able to reduce growth of A. flavus and aflatoxin production when applied onto pistachio trees. High levels of 2-PE are lethal to A. flavus and other fungi. However, at low levels, the underlying mechanism of 2-PE to inhibit aflatoxin production remains unclear. In this study, we characterized the temporal transcriptome response of A. flavus to 2-PE at a subinhibitory level (1 µL/mL) using RNA-Seq technology and bioinformatics tools. The treatment during the entire 72 h experimental period resulted in 131 of the total A. flavus 13,485 genes to be significantly impacted, of which 82 genes exhibited decreased expression. They included those encoding conidiation proteins and involved in cyclopiazonic acid biosynthesis. All genes in the aflatoxin gene cluster were also significantly decreased during the first 48 h treatment. Gene Ontology (GO) analyses showed that biological processes with GO terms related to catabolism of propionate and branched-chain amino acids (valine, leucine and isoleucine) were significantly enriched in the down-regulated gene group, while those associated with ribosome biogenesis, translation, and biosynthesis of α-amino acids were over-represented among the up-regulated genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that metabolic pathways negatively impacted among the down-regulated genes parallel to those active at 30 °C, a condition conducive to aflatoxin biosynthesis. In contrast, metabolic pathways positively related to the up-regulated gene group resembled those at 37 °C, which favors rapid fungal growth and is inhibitory to aflatoxin biosynthesis. The results showed that 2-PE at a low level stimulated active growth of A. flavus but concomitantly rendered decreased activities in branched-chain amino acid degradation

  15. Suppression of Aflatoxin Biosynthesis in Aspergillus flavus by 2-Phenylethanol Is Associated with Stimulated Growth and Decreased Degradation of Branched-Chain Amino Acids.

    PubMed

    Chang, Perng-Kuang; Hua, Sui Sheng T; Sarreal, Siov Bouy L; Li, Robert W

    2015-10-01

    The saprophytic soil fungus Aspergillus flavus infects crops and produces aflatoxin. Pichia anomala, which is a biocontrol yeast and produces the major volatile 2-phenylethanol (2-PE), is able to reduce growth of A. flavus and aflatoxin production when applied onto pistachio trees. High levels of 2-PE are lethal to A. flavus and other fungi. However, at low levels, the underlying mechanism of 2-PE to inhibit aflatoxin production remains unclear. In this study, we characterized the temporal transcriptome response of A. flavus to 2-PE at a subinhibitory level (1 μL/mL) using RNA-Seq technology and bioinformatics tools. The treatment during the entire 72 h experimental period resulted in 131 of the total A. flavus 13,485 genes to be significantly impacted, of which 82 genes exhibited decreased expression. They included those encoding conidiation proteins and involved in cyclopiazonic acid biosynthesis. All genes in the aflatoxin gene cluster were also significantly decreased during the first 48 h treatment. Gene Ontology (GO) analyses showed that biological processes with GO terms related to catabolism of propionate and branched-chain amino acids (valine, leucine and isoleucine) were significantly enriched in the down-regulated gene group, while those associated with ribosome biogenesis, translation, and biosynthesis of α-amino acids OPEN ACCESS Toxins 2015, 7 3888 were over-represented among the up-regulated genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that metabolic pathways negatively impacted among the down-regulated genes parallel to those active at 30 °C, a condition conducive to aflatoxin biosynthesis. In contrast, metabolic pathways positively related to the up-regulated gene group resembled those at 37 °C, which favors rapid fungal growth and is inhibitory to aflatoxin biosynthesis. The results showed that 2-PE at a low level stimulated active growth of A. flavus but concomitantly rendered decreased activities in

  16. Alkyl rearrangement processes in organozirconium complexes. Observation of internal alkyl complexes during hydrozirconation

    SciTech Connect

    Chirik, P.J.; Day, M.W.; Labinger, J.A.; Bercaw, J.E.

    1999-11-10

    Isotopically labeled alkyl zirconocene complexes of the form (CpR{sub n}){sub 2}Zr(CH{sub 2}CDR{sub 2}{prime})(X) (CpR{sub n} = alkyl-substituted cyclopentadienyl; R{prime} = H, alkyl group; X = H, D, Me) undergo isomerization of the alkyl ligand as well as exchange with free olefin in solution under ambient conditions. Increasing the substitution on the Cp ring results in slower isomerization reactions, but these steric effects are small. In contrast, changing X has a very large effect on the rate of isomerization. Pure {sigma}-bonding ligands such as methyl and hydride promote rapid isomerization, whereas {pi}-donor ligands inhibit {beta}-H elimination and hence alkyl isomerization. For ({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}Zr(R)(Cl), internal alkyl complexes have been observed for the first time. The rate of isomerization depends on the length of the alkyl group: longer alkyl chains (heptyl, hexyl) isomerize faster than shorter chains (butyl). The transient intermediate species have been identified by a combination of isotopic labeling and {sup 1}H, {sup 2}H, and {sup 13}C NMR experiments. The solid-state structure of the zirconocene cyclopentyl chloride complex, Cp{sub 2}Zr(cyclo-C{sub 5}H{sub 9})(Cl), has been determined by X-ray diffraction.

  17. DNA-directed alkylating ligands as potential antitumor agents: sequence specificity of alkylation by intercalating aniline mustards.

    PubMed

    Prakash, A S; Denny, W A; Gourdie, T A; Valu, K K; Woodgate, P D; Wakelin, L P

    1990-10-23

    The sequence preferences for alkylation of a series of novel parasubstituted aniline mustards linked to the DNA-intercalating chromophore 9-aminoacridine by an alkyl chain of variable length were studied by using procedures analogous to Maxam-Gilbert reactions. The compounds alkylate DNA at both guanine and adenine sites. For mustards linked to the acridine by a short alkyl chain through a para O- or S-link group, 5'-GT sequences are the most preferred sites at which N7-guanine alkylation occurs. For analogues with longer chain lengths, the preference of 5'-GT sequences diminishes in favor of N7-adenine alkylation at the complementary 5'-AC sequence. Magnesium ions are shown to selectively inhibit alkylation at the N7 of adenine (in the major groove) by these compounds but not the alkylation at the N3 of adenine (in the minor groove) by the antitumor antibiotic CC-1065. Effects of chromophore variation were also studied by using aniline mustards linked to quinazoline and sterically hindered tert-butyl-9-aminoacridine chromophores. The results demonstrate that in this series of DNA-directed mustards the noncovalent interactions of the carrier chromophores with DNA significantly modify the sequence selectivity of alkylation by the mustard. Relationships between the DNA alkylation patterns of these compounds and their biological activities are discussed.

  18. Effects of branched-chain amino acid supplementation on plasma concentrations of free amino acids, insulin, and energy substrates in young men.

    PubMed

    Zhang, Yi; Kobayashi, Hisamine; Mawatari, Kazunori; Sato, Juichi; Bajotto, Gustavo; Kitaura, Yasuyuki; Shimomura, Yoshiharu

    2011-01-01

    The present study was conducted to examine alterations in the concentrations of plasma free amino acids, glucose, insulin, free fatty acids (FFAs), and urea nitrogen induced by branched-chain amino acid (BCAA) supplementation in young men. Overnight-fasted subjects ingested drinks containing 1 or 5 g of a BCAA mixture (weight ratio of 1 : 2.3 : 1.2 for isoleucine : leucine : valine), and blood was intermittently collected for 3 h after ingestion. Ingestion of the BCAA mixture resulted in significant increases in the plasma concentrations of individual BCAAs, corresponding to the amounts of amino acids ingested. On the other hand, plasma concentrations of methionine and aromatic amino acids tended to decrease in the trial with 5 g BCAAs, suggesting that BCAA ingestion affects the metabolism of these amino acids. The ingestion of BCAAs temporarily increased plasma insulin levels and affected plasma concentrations of FFAs, but had almost no effect on glucose or urea nitrogen. PMID:21512300

  19. Regulation of Synthesis of the Branched-Chain Amino Acids and Cognate Aminoacyl-Transfer Ribonucleic Acid Synthetases of Escherichia coli: a Common Regulatory Element

    PubMed Central

    Jackson, Julius; Williams, L. S.; Umbarger, H. E.

    1974-01-01

    Regulation of isoleucine, valine, and leucine biosynthesis and isoleucyl-, valyl-, and leucyl-transfer ribonucleic acid (tRNA) synthetase formation was examined in two mutant strains of Escherichia coli. One mutant was selected for growth resistance to the isoleucine analogue, ketomycin, and the other was selected for growth resistance to both trifluoroleucine and valine. Control of the synthesis of the branched-chain amino acids by repression was altered in both of these mutants. They also exhibited altered control of formation of isoleucyl-tRNA synthetase (EC 6.1.15, isoleucine:sRNA ligase, AMP), valyl-tRNA synthetase (EC 6.1.1.9, valine:sRNA ligase, AMP), and leucyl-tRNA synthetase (EC 6.1.1.4, leucine:sRNA ligase, AMP). These results suggest the existence of a common element for the control of these two classes of enzymes in Escherichia coli. PMID:4612020

  20. Morphology of blends of linear and long-chain-branched polyethylenes in the solid state: A study by SANS, SAXS, and DSC

    SciTech Connect

    Wignall, G.D.; Londono, J.D.; Lin, J.S.; Alamo, R.G.; Galante, M.J.; Mandelkern, L.

    1995-04-24

    Differential scanning calorimetry (DSC), small-angle neutron scattering (SANS), and X-ray scattering (SAXS) have been used to investigate the solid-state morphology of blends of linear (high density) and long-chain-branched (low-density) polyethylenes (HDPE/LDPE). The blends are homogeneous in the melt, as previously demonstrated by SANS using the contrast obtained by deuterating the linear polymer. However, due to the structural and melting point differences ({approximately} 20 C) between HDPE and LDPE, the components may phase segregate on slow cooling (0.75 C/min). For high concentrations ({phi} {ge} 0.5) of HDPE, relatively high rates of crystallization of the linear component lead to the formation of separate stacks of HDPE and LDPE lamellae, as indicated by two-peak SAXS curves. For predominantly branched blends, the difference in crystallization rate of the components becomes smaller and only one SAXS peak is observed, indicating that the two species are in the same lamellar stack. Moreover, the phases no longer consist of the pure component and the HDPE lamellae contain up to 15--20% LDPE (and vice versa). Rapid quenching into dry ice/2-propanol ({minus}78 C) produces only one SAXS peak (and hence one lamellar stack) over the whole concentration range. The blends show extensive cocrystallization, along with a tendency for the branched material to be preferentially located in the amorphous interlamellar regions. For high concentrations ({phi} > 0.5) of HDPE-D, the overall scattering length density (SLD) is high and the excess concentration of LDPE between the lamellae enhances the SLD contrast between the crystalline and amorphous phases. Thus, the interlamellar spacing (long period) is clearly visible in the SANS pattern. The blend morphology is a strong function of the quenching rate, and samples quenched less rapidly (e.g., into water at 23 C) are similar to slowly cooled blends.

  1. A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems.

    PubMed

    Zigler, J Samuel; Hodgkinson, Colin A; Wright, Megan; Klise, Andrew; Sundin, Olof; Broman, Karl W; Hejtmancik, Fielding; Huang, Hao; Patek, Bonnie; Sergeev, Yuri; Hose, Stacey; Brayton, Cory; Xaiodong, Jiao; Vasquez, David; Maragakis, Nicholas; Mori, Susumu; Goldman, David; Hoke, Ahmet; Sinha, Debasish

    2016-01-01

    A novel mutation, causing a phenotype we named frogleg because its most obvious characteristic is a severe splaying of the hind limbs, arose spontaneously in a colony of Sprague-Dawley rats. Frogleg is a complex phenotype that includes abnormalities in hind limb function, reduced brain weight with dilated ventricles and infertility. Using micro-satellite markers spanning the entire rat genome, the mutation was mapped to a region of rat chromosome 1 between D1Rat131 and D1Rat287. Analysis of whole genome sequencing data within the linkage interval, identified a missense mutation in the branched-chain alpha-keto dehydrogenase kinase (Bckdk) gene. The protein encoded by Bckdk is an integral part of an enzyme complex located in the mitochondrial matrix of many tissues which regulates the levels of the branched-chain amino acids (BCAAs), leucine, isoleucine and valine. BCAAs are essential amino acids (not synthesized by the body), and circulating levels must be tightly regulated; levels that are too high or too low are both deleterious. BCKDK phosphorylates Ser293 of the E1α subunit of the BCKDH protein, which catalyzes the rate-limiting step in the catabolism of the BCAAs, inhibiting BCKDH and thereby, limiting breakdown of the BCAAs. In contrast, when Ser293 is not phosphorylated, BCKDH activity is unchecked and the levels of the BCAAs will decrease dramatically. The mutation is located within the kinase domain of Bckdk and is predicted to be damaging. Consistent with this, we show that in rats homozygous for the mutation, phosphorylation of BCKDH in the brain is markedly decreased relative to wild type or heterozygous littermates. Further, circulating levels of the BCAAs are reduced by 70-80% in animals homozygous for the mutation. The frogleg phenotype shares important characteristics with a previously described Bckdk knockout mouse and with human subjects with Bckdk mutations. In addition, we report novel data regarding peripheral neuropathy of the hind limbs

  2. Leucine-induced activation of translational initiation is partly regulated by the branched-chain {alpha}-keto acid dehydrogenase complex in C2C12 cells

    SciTech Connect

    Nakai, Naoya . E-mail: nakai@hss.osaka-u.ac.jp; Shimomura, Yoshiharu; Tamura, Tomohiro; Tamura, Noriko; Hamada, Koichiro; Kawano, Fuminori; Ohira, Yoshinobu

    2006-05-19

    Branched-chain amino acid leucine has been shown to activate the translational regulators through the mammalian target of rapamycin. However, the leucine's effects are self-limiting because leucine promotes its own disposal by an oxidative pathway. The irreversible and rate-limiting step in the leucine oxidation pathway is catalyzed by the branched-chain {alpha}-keto acid dehydrogenase (BCKDH) complex. The complex contains E1 ({alpha}2{beta}2), E2, and E3 subunits, and its activity is abolished by phosphorylation of the E1{alpha} subunit by BCKDH kinase. The relationship between the activity of BCKDH complex and leucine-mediated activation of the protein translation was investigated using the technique of RNA interference. The activity of BCKDH complex in C2C12 cell was modulated by transfection of small interfering RNA (siRNA) for BCKDH E2 subunit or BCKDH kinase. Transfection of siRNAs decreased the mRNA expression and protein amount of corresponding gene. Suppression of either E2 subunit or kinase produced opposite effects on the cell proliferation and the activation of translational regulators by leucine. Suppression of BCKDH kinase for 48 h resulted in decreasing cell proliferation. In contrast, E2 suppression led to increased amount of total cellular protein. The phosphorylation of p70 S6 kinase by leucine was increased in E2-siRNA transfected C2C12 cells, whereas the leucine's effect was diminished in kinase-siRNA transfected cells. These results suggest that the activation of the translational regulators by leucine was partly regulated by the activity of BCKDH complex.

  3. A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems

    PubMed Central

    Zigler, J. Samuel; Hodgkinson, Colin A.; Wright, Megan; Klise, Andrew; Broman, Karl W.; Huang, Hao; Patek, Bonnie; Sergeev, Yuri; Hose, Stacey; Xaiodong, Jiao; Vasquez, David; Maragakis, Nicholas; Mori, Susumu; Goldman, David; Sinha, Debasish

    2016-01-01

    A novel mutation, causing a phenotype we named frogleg because its most obvious characteristic is a severe splaying of the hind limbs, arose spontaneously in a colony of Sprague-Dawley rats. Frogleg is a complex phenotype that includes abnormalities in hind limb function, reduced brain weight with dilated ventricles and infertility. Using micro-satellite markers spanning the entire rat genome, the mutation was mapped to a region of rat chromosome 1 between D1Rat131 and D1Rat287. Analysis of whole genome sequencing data within the linkage interval, identified a missense mutation in the branched-chain alpha-keto dehydrogenase kinase (Bckdk) gene. The protein encoded by Bckdk is an integral part of an enzyme complex located in the mitochondrial matrix of many tissues which regulates the levels of the branched-chain amino acids (BCAAs), leucine, isoleucine and valine. BCAAs are essential amino acids (not synthesized by the body), and circulating levels must be tightly regulated; levels that are too high or too low are both deleterious. BCKDK phosphorylates Ser293 of the E1α subunit of the BCKDH protein, which catalyzes the rate-limiting step in the catabolism of the BCAAs, inhibiting BCKDH and thereby, limiting breakdown of the BCAAs. In contrast, when Ser293 is not phosphorylated, BCKDH activity is unchecked and the levels of the BCAAs will decrease dramatically. The mutation is located within the kinase domain of Bckdk and is predicted to be damaging. Consistent with this, we show that in rats homozygous for the mutation, phosphorylation of BCKDH in the brain is markedly decreased relative to wild type or heterozygous littermates. Further, circulating levels of the BCAAs are reduced by 70–80% in animals homozygous for the mutation. The frogleg phenotype shares important characteristics with a previously described Bckdk knockout mouse and with human subjects with Bckdk mutations. In addition, we report novel data regarding peripheral neuropathy of the hind limbs

  4. Impact of combined resistance and aerobic exercise training on branched-chain amino acid turnover, glycine metabolism and insulin sensitivity in overweight humans

    PubMed Central

    Glynn, Erin L.; Piner, Lucy W.; Huffman, Kim M.; Slentz, Cris A.; Elliot-Penry, Lorraine; AbouAssi, Hiba; White, Phillip J.; Bain, James R.; Muehlbauer, Michael J.; Ilkayeva, Olga R.; Stevens, Robert D.; Porter Starr, Kathryn N.; Bales, Connie W.; Volpi, Elena; Brosnan, M. Julia; Trimmer, Jeff K.; Rolph, Timothy P.

    2016-01-01

    Aims/hypotheses Obesity is associated with decreased insulin sensitivity (IS) and elevated plasma branched-chain amino acids (BCAAs). The purpose of this study was to investigate the relationship between BCAA metabolism and IS in overweight (OW) individuals during exercise intervention. Methods Whole-body leucine turnover, IS by hyperinsulinaemic–euglycaemic clamp, and circulating and skeletal muscle amino acids, branched-chain α-keto acids and acylcarnitines were measured in ten healthy controls (Control) and nine OW, untrained, insulin-resistant individuals (OW-Untrained). OW-Untrained then underwent a 6 month aerobic and resistance exercise programme and repeated testing (OW-Trained). Results IS was higher in Control vs OW-Untrained and increased significantly following exercise. IS was lower in OW-Trained vs Control expressed relative to body mass, but was not different from Control when normalised to fat-free mass (FFM). Plasma BCAAs and leucine turnover (relative to FFM) were higher in OW-Untrained vs Control, but did not change on average with exercise. Despite this, within individuals, the decrease in molar sum of circulating BCAAs was the best metabolic predictor of improvement in IS. Circulating glycine levels were higher in Control and OW-Trained vs OW-Untrained, and urinary metabolic profiling suggests that exercise induces more efficient elimination of excess acyl groups derived from BCAA and aromatic amino acid (AA) metabolism via formation of urinary glycine adducts. Conclusions/interpretation A mechanism involving more efficient elimination of excess acyl groups derived from BCAA and aromatic AA metabolism via glycine conjugation in the liver, rather than increased BCAA disposal through oxidation and turnover, may mediate interactions between exercise, BCAA metabolism and IS. Trial registration Clinicaltrials.gov NCT01786941 PMID:26254576

  5. Transcriptomic and Reverse Genetic Analysesof Branched-Chain Fatty Acid and Acyl Sugar Production in Solanum pennellii and Nicotiana benthamiana1[W][OA

    PubMed Central

    Slocombe, Stephen P.; Schauvinhold, Ines; McQuinn, Ryan P.; Besser, Katrin; Welsby, Nicholas A.; Harper, Andrea; Aziz, Naveed; Li, Yi; Larson, Tony R.; Giovannoni, James; Dixon, Richard A.; Broun, Pierre

    2008-01-01

    Acyl sugars containing branched-chain fatty acids (BCFAs) are exuded by glandular trichomes of many species in Solanaceae, having an important defensive role against insects. From isotope-feeding studies, two modes of BCFA elongation have been proposed: (1) fatty acid synthase-mediated two-carbon elongation in the high acyl sugar-producing tomato species Solanum pennellii and Datura metel; and (2) α-keto acid elongation-mediated one-carbon increments in several tobacco (Nicotiana) species and a Petunia species. To investigate the molecular mechanisms underlying BCFAs and acyl sugar production in trichomes, we have taken a comparative genomic approach to identify critical enzymatic steps followed by gene silencing and metabolite analysis in S. pennellii and Nicotiana benthamiana. Our study verified the existence of distinct mechanisms of acyl sugar synthesis in Solanaceae. From microarray analyses, genes associated with α-keto acid elongation were found to be among the most strongly expressed in N. benthamiana trichomes only, supporting this model in tobacco species. Genes encoding components of the branched-chain keto-acid dehydrogenase complex were expressed at particularly high levels in trichomes of both species, and we show using virus-induced gene silencing that they are required for BCFA production in both cases and for acyl sugar synthesis in N. benthamiana. Functional analysis by down-regulation of specific KAS I genes and cerulenin inhibition indicated the involvement of the fatty acid synthase complex in BCFA production in S. pennellii. In summary, our study highlights both conserved and divergent mechanisms in the production of important defense compounds in Solanaceae and defines potential targets for engineering acyl sugar production in plants for improved pest tolerance. PMID:18931142

  6. A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems.

    PubMed

    Zigler, J Samuel; Hodgkinson, Colin A; Wright, Megan; Klise, Andrew; Sundin, Olof; Broman, Karl W; Hejtmancik, Fielding; Huang, Hao; Patek, Bonnie; Sergeev, Yuri; Hose, Stacey; Brayton, Cory; Xaiodong, Jiao; Vasquez, David; Maragakis, Nicholas; Mori, Susumu; Goldman, David; Hoke, Ahmet; Sinha, Debasish

    2016-01-01

    A novel mutation, causing a phenotype we named frogleg because its most obvious characteristic is a severe splaying of the hind limbs, arose spontaneously in a colony of Sprague-Dawley rats. Frogleg is a complex phenotype that includes abnormalities in hind limb function, reduced brain weight with dilated ventricles and infertility. Using micro-satellite markers spanning the entire rat genome, the mutation was mapped to a region of rat chromosome 1 between D1Rat131 and D1Rat287. Analysis of whole genome sequencing data within the linkage interval, identified a missense mutation in the branched-chain alpha-keto dehydrogenase kinase (Bckdk) gene. The protein encoded by Bckdk is an integral part of an enzyme complex located in the mitochondrial matrix of many tissues which regulates the levels of the branched-chain amino acids (BCAAs), leucine, isoleucine and valine. BCAAs are essential amino acids (not synthesized by the body), and circulating levels must be tightly regulated; levels that are too high or too low are both deleterious. BCKDK phosphorylates Ser293 of the E1α subunit of the BCKDH protein, which catalyzes the rate-limiting step in the catabolism of the BCAAs, inhibiting BCKDH and thereby, limiting breakdown of the BCAAs. In contrast, when Ser293 is not phosphorylated, BCKDH activity is unchecked and the levels of the BCAAs will decrease dramatically. The mutation is located within the kinase domain of Bckdk and is predicted to be damaging. Consistent with this, we show that in rats homozygous for the mutation, phosphorylation of BCKDH in the brain is markedly decreased relative to wild type or heterozygous littermates. Further, circulating levels of the BCAAs are reduced by 70-80% in animals homozygous for the mutation. The frogleg phenotype shares important characteristics with a previously described Bckdk knockout mouse and with human subjects with Bckdk mutations. In addition, we report novel data regarding peripheral neuropathy of the hind limbs.

  7. Effects of alkyl parabens on plant pathogenic fungi.

    PubMed

    Ito, Shinsaku; Yazawa, Satoru; Nakagawa, Yasutaka; Sasaki, Yasuyuki; Yajima, Shunsuke

    2015-04-15

    Alkyl parabens are used as antimicrobial preservatives in cosmetics, food, and pharmaceutical products. However, the mode of action of these chemicals has not been assessed thoroughly. In this study, we determined the effects of alkyl parabens on plant pathogenic fungi. All the fungi tested, were susceptible to parabens. The effect of linear alkyl parabens on plant pathogenic fungi was related to the length of the alkyl chain. In addition, the antifungal activity was correlated with the paraben-induced inhibition of oxygen consumption. The antifungal activity of linear alkyl parabens likely originates, at least in part, from their ability to inhibit the membrane respiratory chain, especially mitochondrial complex II. Additionally, we determined that some alkyl parabens inhibit Alternaria brassicicola infection of cabbage.

  8. Asymmetric 1-alkyl-2-acyl phosphatidylcholine: a helper lipid for enhanced non-viral gene delivery.

    PubMed

    Huang, Zhaohua; Li, Weijun; Szoka, Francis C

    2012-05-01

    Rationally designed asymmetrical alkylacyl phosphatidylcholines (APC) have been synthesized and evaluated as helper lipids for non-viral gene delivery. A long aliphatic chain (C22-C24) was introduced at the 1-position of glycerol backbone, a branched lipid chain (C18) at the 2-position, and a phosphocholine head group at the 3-position. The fusogenicity of APC depends on the length and degree of saturation of the alkyl chain. Cationic lipids were formulated with APC as either lipoplexes or nanolipoparticles, and evaluated for their stability, transfection efficiency, and cytotoxicity. APC mediated high in vitro transfection efficiency, and had low cytotoxicity. Small nanolipoparticles (less than 100 nm) can be obtained with APC by applying as low as 0.1% PEG-lipid. Our study extends the type of helper lipids that are suitable for gene transfer and points the way to improve non-viral nucleic acid delivery system other than the traditional cationic lipids optimization.

  9. Biphenyl-3-yl alkylcarbamates as fatty acid amide hydrolase (FAAH) inhibitors: Steric effects of N-alkyl chain on rat plasma and liver stability

    PubMed Central

    Vacondio, Federica; Silva, Claudia; Lodola, Alessio; Carmi, Caterina; Rivara, Silvia; Duranti, Andrea; Tontini, Andrea; Sanchini, Silvano; Clapper, Jason R.; Piomelli, Daniele; Tarzia, Giorgio; Mor, Marco

    2013-01-01

    Secondary alkylcarbamic acid biphenyl-3-yl esters are a class of Fatty Acid Amide Hydrolase (FAAH) inhibitors, which include the reference compounds URB597 and URB694. Given the intrinsic reactivity of the carbamate group, the in vivo potency of these molecules in rats is strongly affected by their hydrolysis in plasma or hepatic metabolism. In the present study, in vitro chemical and metabolic stability assays (rat plasma and rat liver S9 fraction) were used to investigate the structure-property relationships (SPRs) for a focused series of title compounds, where lipophilicity and steric hindrance of the carbamate N-substituent had been modulated. The resulting degradation rates indicate that a secondary or tertiary alkyl group at the carbamate nitrogen atom increases hydrolytic stability towards rat plasma esterases. The calculated solvent accessible surface area (SASA) of the carbamate fragment was employed to describe the differences observed in rate constants of hydrolysis in rat plasma (log kplasma), suggesting that stability in plasma increases if the substituent exerts a shielding effect on the carbamate carbonyl. Stability in rat liver S9 fraction is increased when a tertiary carbon is bound to the carbamate nitrogen atom, while other steric effects showed complex relationships with degradation rates. The SPRs here described may be applied at the pharmacokinetic optimization of other classes of carbamate FAAH inhibitors. PMID:21820769

  10. 40 CFR 721.10283 - Poly[oxy(methyl-1,2-ethanediyl)], .alpha.-sulfo-.omega.-hydroxy-, C12-13-branched and linear...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-, C12-13-branched and linear alkyl ethers, sodium salts. 721.10283 Section 721.10283 Protection of...-.omega.-hydroxy-, C12-13-branched and linear alkyl ethers, sodium salts. (a) Chemical substance and...-.omega.-hydroxy-, C12-13-branched and linear alkyl ethers, sodium salts (PMN P-10-486; CAS No....

  11. 40 CFR 721.10284 - Poly[oxy(methyl-1,2-ethanediyl)], .alpha.-sulfo-.omega.-hydroxy-, C14-15-branched and linear...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-, C14-15-branched and linear alkyl ethers, sodium salts. 721.10284 Section 721.10284 Protection of...-.omega.-hydroxy-, C14-15-branched and linear alkyl ethers, sodium salts. (a) Chemical substance and...-.omega.-hydroxy-, C14-15-branched and linear alkyl ethers, sodium salts (PMN P-10-487; CAS No....

  12. Clusters of branched aliphatic side chains serve as cores of stability in the native state of the HisF TIM barrel protein.

    PubMed

    Gangadhara, Basavanapura N; Laine, Jennifer M; Kathuria, Sagar V; Massi, Francesca; Matthews, C Robert

    2013-03-25

    Imidazole-3-glycerol phosphate synthase is a heterodimeric allosteric enzyme that catalyzes consecutive reactions in imidazole biosynthesis through its HisF and HisH subunits. The unusually slow unfolding reaction of the isolated HisF TIM barrel domain from the thermophilic bacteria, Thermotoga maritima, enabled an NMR-based site-specific analysis of the main-chain hydrogen bonds that stabilize its native conformation. Very strong protection against exchange with solvent deuterium in the native state was found in a subset of buried positions in α-helices and pervasively in the underlying β-strands associated with a pair of large clusters of isoleucine, leucine and valine (ILV) side chains located in the α7(βα)8(βα)1-2 and α2(βα)3-6β7 segments of the (βα)8 barrel. The most densely packed region of the large cluster, α3(βα)4-6β7, correlates closely with the core of stability previously observed in computational, protein engineering and NMR dynamics studies, demonstrating a key role for this cluster in determining the thermodynamic and structural properties of the native state of HisF. When considered with the results of previous studies where ILV clusters were found to stabilize the hydrogen-bonded networks in folding intermediates for other TIM barrel proteins, it appears that clusters of branched aliphatic side chains can serve as cores of stability across the entire folding reaction coordinate of one of the most common motifs in biology.

  13. Precision Polyolefin Structure: Modeling Polyethylene Containing Methyl and Ethyl Branches

    NASA Astrophysics Data System (ADS)

    Rojas, Giovanni; Wagener, Kenneth B.

    Sequenced copolymers of ethylene and diverse species have been created using acyclic diene metathesis (ADMET) polymerization, a step growth, condensation- type polymerization driven to high conversion by the removal of ethylene. ADMET permits control over branch content and branch length, which can be predetermined during the monomer synthesis, allowing sequence control in the resultant unsaturated polymer. Monomers are symmetrical α,ωdienes with a pendant functionality. Diverse functional groups are compatible with ADMET polymerization when Schrock’s or first-generation Grubb’s catalysts are used. Saturation with hydrogen after ADMET polymerization affords a polyethylene (PE) backbone bearing specific functionalities in precise places. Varying both the pendant functional group and the spacing between functionalities alters the physical and chemical properties of the polymer. Incorporation of alkyl chains into the PE backbone via ADMET leads to the study of perfect structures modeling the copolymerization of ethylene with α-olefins such as 1-propene, 1-butene, 1-hexene, and 1-octene.

  14. Whey protein supplementation does not alter plasma branched-chained amino acid profiles but results in unique metabolomics patterns in obese women enrolled in an 8-week weight loss trial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: It has been suggested that perturbations in branched-chain amino acid (BCAA) catabolism are associated with insulin resistance and contribute to elevated systemic BCAAs. Evidence in rodents suggests dietary protein rich in BCAAs can increase BCAA catabolism, but there is limited evidence...

  15. Structural and Thermodynamic Basis for Weak Interactions between Dihydrolipoamide Dehydrogenase and Subunit-binding Domain of the Branched-chain [alpha]-Ketoacid Dehydrogenase Complex

    SciTech Connect

    Brautigam, Chad A.; Wynn, R. Max; Chuang, Jacinta L.; Naik, Mandar T.; Young, Brittany B.; Huang, Tai-huang; Chuang, David T.

    2012-02-27

    The purified mammalian branched-chain {alpha}-ketoacid dehydrogenase complex (BCKDC), which catalyzes the oxidative decarboxylation of branched-chain {alpha}-keto acids, is essentially devoid of the constituent dihydrolipoamide dehydrogenase component (E3). The absence of E3 is associated with the low affinity of the subunit-binding domain of human BCKDC (hSBDb) for hE3. In this work, sequence alignments of hSBDb with the E3-binding domain (E3BD) of the mammalian pyruvate dehydrogenase complex show that hSBDb has an arginine at position 118, where E3BD features an asparagine. Substitution of Arg-118 with an asparagine increases the binding affinity of the R118N hSBDb variant (designated hSBDb*) for hE3 by nearly 2 orders of magnitude. The enthalpy of the binding reaction changes from endothermic with the wild-type hSBDb to exothermic with the hSBDb* variant. This higher affinity interaction allowed the determination of the crystal structure of the hE3/hSBDb* complex to 2.4-{angstrom} resolution. The structure showed that the presence of Arg-118 poses a unique, possibly steric and/or electrostatic incompatibility that could impede E3 interactions with the wild-type hSBDb. Compared with the E3/E3BD structure, the hE3/hSBDb* structure has a smaller interfacial area. Solution NMR data corroborated the interactions of hE3 with Arg-118 and Asn-118 in wild-type hSBDb and mutant hSBDb*, respectively. The NMR results also showed that the interface between hSBDb and hE3 does not change significantly from hSBDb to hSBDb*. Taken together, our results represent a starting point for explaining the long standing enigma that the E2b core of the BCKDC binds E3 far more weakly relative to other {alpha}-ketoacid dehydrogenase complexes.

  16. Branched chain in situ hybridization for albumin as a marker of hepatocellular differentiation: evaluation of manual and automated in situ hybridization platforms

    PubMed Central

    Shahid, Mohammad; Mubeen, Aysha; Tse, Julie; Kakar, Sanjay; Bateman, Adrian; Borger, Darrell; Rivera, Miguel; Ting, David T.; Deshpande, Vikram

    2015-01-01

    Introduction Albumin, widely recognized as a highly sensitive and specific marker of hepatocellular carcinoma (HCC) is currently unavailable in the diagnostic laboratory because of the lack of a robust platform. In a prior study we detected albumin mRNA in the majority of intrahepatic cholangiocarcinomas using a novel branched chain RNA in situ hybridization (ISH) platform. We now explore the utility of albumin ISH as a marker of hepatocellular differentiation in hepatocellular carcinomas, and compare its sensitivity with Hep Par 1 and Arginase-1. Methods We evaluated 93 HCCs and its mimics including neuroendocrine tumors of the gastrointestinal tract (n= 31), neuroendocrine tumors of the pancreas (n= 163), melanoma (n= 15), and gallbladder carcinoma (n=34). We performed ISH for albumin and immunohistochemistry for Hep Par 1 and Arginase-1. Five previously uncharacterized hepatic neoplasms from our files were also evaluated. Immunohistochemistry for Arginase-1 was performed on 59 intrahepatic cholangiocarcinomas. In addition, 43 HCCs evaluated on the manual platform, were also examined on the automated instrument. Results 55% of HCCs were moderately differentiated and 39% poorly differentiated. The sensitivity of ISH for Albumin was 99% with 92 of 93 of HCCs staining positive for albumin. In contrast to ISH, the sensitivity of immunohistochemistry for Hep Par1 and Arginase-1 was 84 % and 83 %, respectively. The sensitivity of albumin for poorly differentiated HCCs was 99%, while that for Arginase-1 and Hep Par 1 was 71% and 64%, respectively. 97% of the HCCs showed albumin positivity in >50% of tumor cells using the ISH platform, as compared to 76% and 70% for Hep Par 1 and Arginase-1 immunohistochemistry, respectively. 3 of the 5 previously uncharacterized neoplasms were positive for albumin ISH. Automated albumin ISH platform performed equivalently to the manual format, with albumin reactivity in >50% of tumor cells in all 43 cases that were tested on both

  17. A new approach to the side chain formation of 24-alkyl-22-hydroxy steroids: application to the preparation of early brassinolide biosynthetic precursors.

    PubMed

    Hurski, Alaksiej L; Zhabinskii, Vladimir N; Khripach, Vladimir A

    2012-06-01

    A new synthetic route to 22S-hydroxy-24R-methyl steroids has been developed and applied for the preparation of cathasterone, (22S)-hydroxycampesterol, and 6-deoxocathasterone, which are precursors in the early stages of the biosynthesis of brassinolide. The construction of the steroid side chain with the correct stereochemistry at C-24 is based on the use of Claisen rearrangement. The introduction of the 22-hydroxyl group has been achieved by epoxidation of the Δ(22)-double bond, nucleophilic opening of the intermediate mesyl epoxide with sodium sulfide, and desulfurization of the formed tetrahydrothiophenes with Raney nickel.

  18. A new approach to the side chain formation of 24-alkyl-22-hydroxy steroids: application to the preparation of early brassinolide biosynthetic precursors.

    PubMed

    Hurski, Alaksiej L; Zhabinskii, Vladimir N; Khripach, Vladimir A

    2012-06-01

    A new synthetic route to 22S-hydroxy-24R-methyl steroids has been developed and applied for the preparation of cathasterone, (22S)-hydroxycampesterol, and 6-deoxocathasterone, which are precursors in the early stages of the biosynthesis of brassinolide. The construction of the steroid side chain with the correct stereochemistry at C-24 is based on the use of Claisen rearrangement. The introduction of the 22-hydroxyl group has been achieved by epoxidation of the Δ(22)-double bond, nucleophilic opening of the intermediate mesyl epoxide with sodium sulfide, and desulfurization of the formed tetrahydrothiophenes with Raney nickel. PMID:22487564

  19. Supplementation with branched-chain amino acids to a low-protein diet regulates intestinal expression of amino acid and peptide transporters in weanling pigs.

    PubMed

    Zhang, Shihai; Qiao, Shiyan; Ren, Man; Zeng, Xiangfang; Ma, Xi; Wu, Zhenlong; Thacker, Philip; Wu, Guoyao

    2013-11-01

    This study determined the effects of dietary branched-chain amino acids (AA) (BCAA) on growth performance, expression of jejunal AA and peptide transporters, and the colonic microflora of weanling piglets fed a low-protein (LP) diet. One hundred and eight Large White × Landrace × Duroc piglets (weaned at 28 days of age) were fed a normal protein diet (NP, 20.9 % crude protein), an LP diet (LP, 17.1 % crude protein), or an LP diet supplemented with BCAA (LP + BCAA, 17.9 % crude protein) for 14 days. Dietary protein restriction reduced piglet growth performance and small-intestinal villous height, which were restored by BCAA supplementation to the LP diet to values for the NP diet. Serum concentrations of BCAA were reduced in piglets fed the LP diet while those in piglets fed the LP + BCAA diet were similar to values for the NP group. mRNA levels for Na(+)-neutral AA exchanger-2, cationic AA transporter-1, b(0,+) AA transporter, and 4F2 heavy chain were more abundant in piglets fed the LP + BCAA diet than the LP diet. However, mRNA and protein levels for peptide transporter-1 were lower in piglets fed the LP + BCAA diet as compared to the LP diet. The colonic microflora did not differ among the three groups of pigs. In conclusion, growth performance, intestinal development, and intestinal expression of AA transporters in weanling piglets are enhanced by BCAA supplementation to LP diets. Our findings provide a new molecular basis for further understanding of BCAA as functional AA in animal nutrition.

  20. CypD−/− Hearts HaveAltered Levels of Proteins Involved in Krebs Cycle, Branch Chain Amino Acid Degradation and Pyruvate Metabolism

    PubMed Central

    Menazza, Sara; Wong, Renee; Nguyen, Tiffany; Wang, Guanghui; Gucek, Marjan; Murphy, Elizabeth

    2013-01-01

    Cyclophilin D (CypD) is a mitochondrial chaperone that has been shown to regulate the mitochondrial permeability transition pore (MPTP). MPTP opening is a major determinant of mitochondrial dysfunction and cardiomyocyte death during ischemia/reperfusion (I/R) injury. Mice lacking CypD have been widely used to study regulation of the MPTP, and it has been shown recently that genetic depletion of CypD correlates with elevated levels of mitochondrial Ca2+. The present study aimed to characterize the metabolic changes in CypD−/− hearts. Initially, we used a proteomics approach to examine protein changes in CypD−/− mice. Using pathway analysis we found that CypD−/− hearts have alteration in branched chain amino acid metabolism, pyruvate metabolism and the Krebs cycle. We tested whether these metabolic changes were due to inhibition of electron transfer from these metabolic pathways into the electron transport chain. As we found decreased levels of succinate dehydrogenase and electron transfer flavoprotein in the proteomics analysis, we examined whether activities of these enzymes might be altered. However, we found no alterations in their activities. The proteomics study also showed a 23% decrease in carnitine -palmitoyltransferase 1 (CPT1), which prompted us to perform a metabolomics analysis. Consistent with the decrease in CPT1, we found a significant decrease in C4/Ci4, C5-OH/C3-DC, C12:1, C14:1, C16:1, and C20:3 acyl carnitines in hearts from CypD−/− mice. In summary, CypD−/− hearts exhibit changes in many metabolic pathways and caution should be used when interpreting results from these mice as due solely to inhibition of the MPTP. PMID:23262437

  1. Mechanism of toxicity of the branched-chain fatty acid phytanic acid, a marker of Refsum disease, in astrocytes involves mitochondrial impairment.

    PubMed

    Reiser, Georg; Schönfeld, Peter; Kahlert, Stefan

    2006-01-01

    Phytanic acid is a saturated branched-chain fatty acid, which is formed by bacterial degradation of chlorophyll in the intestinal tract of ruminants. The methyl group in beta-position prevents degradation of phytanic acid by the beta-oxidation pathway. Therefore, degradation of phytanic acid is initiated by alpha-oxidation in peroxisomes. The inherited peroxisomal disorder Refsum disease is characterised by accumulation of phytanic acid. Unusually high concentrations of phytanic acid can be found in the plasma of Refsum disease patients, who suffer from neurodegeneration and muscle dystrophy. Phytanic acid has been suggested to be causally involved in the clinical symptoms. To elucidate the pathogenic mechanism, we investigated the influence of phytanic acid in rat hippocampal astrocytes by monitoring the cytosolic Ca(2+) concentration, the mitochondrial membrane potential (Deltapsi(m)), the generation of reactive oxygen species as well as the cellular ATP level. In response to phytanic acid (100 microM) cytosolic Ca(2+) was quickly increased. The phytanic acid-evoked Ca(2+) response was transient and involved activation of intracellular Ca(2+) stores. In isolated rat brain mitochondria, phytanic acid dissipated Deltapsi(m) in a reversible and dose-dependent manner. Moreover, phytanic acid released cytochrome c from mitochondria. Depending on the mitochondrial activity state, phytanic acid either stimulated or inhibited the electron flux within the respiratory chain. In addition, phytanic acid induced substantial generation of reactive oxygen species in isolated mitochondria as well as in intact cells. Phytanic acid caused cell death of astrocytes within a few hours of exposure. In conclusion, we suggest that phytanic acid initiates astrocyte cell death by activating the mitochondrial route of apoptosis.

  2. CypD(-/-) hearts have altered levels of proteins involved in Krebs cycle, branch chain amino acid degradation and pyruvate metabolism.

    PubMed

    Menazza, Sara; Wong, Renee; Nguyen, Tiffany; Wang, Guanghui; Gucek, Marjan; Murphy, Elizabeth

    2013-03-01

    Cyclophilin D (CypD) is a mitochondrial chaperone that has been shown to regulate the mitochondrial permeability transition pore (MPTP). MPTP opening is a major determinant of mitochondrial dysfunction and cardiomyocyte death during ischemia/reperfusion (I/R) injury. Mice lacking CypD have been widely used to study regulation of the MPTP, and it has been shown recently that genetic depletion of CypD correlates with elevated levels of mitochondrial Ca(2+). The present study aimed to characterize the metabolic changes in CypD(-/-) hearts. Initially, we used a proteomics approach to examine protein changes in CypD(-/-) mice. Using pathway analysis, we found that CypD(-/-) hearts have alterations in branched chain amino acid metabolism, pyruvate metabolism and the Krebs cycle. We tested whether these metabolic changes were due to inhibition of electron transfer from these metabolic pathways into the electron transport chain. As we found decreased levels of succinate dehydrogenase and electron transfer flavoprotein in the proteomics analysis, we examined whether activities of these enzymes might be altered. However, we found no alterations in their activities. The proteomics study also showed a 23% decrease in carnitine-palmitoyltransferase 1 (CPT1), which prompted us to perform a metabolomics analysis. Consistent with the decrease in CPT1, we found a significant decrease in C4/Ci4, C5-OH/C3-DC, C12:1, C14:1, C16:1, and C20:3 acyl carnitines in hearts from CypD(-/-) mice. In summary, CypD(-/-) hearts exhibit changes in many metabolic pathways and caution should be used when interpreting results from these mice as due solely to inhibition of the MPTP.

  3. Biosynthesis of alkyl lysophosphatidic acid by diacylglycerol kinases.

    PubMed

    Gellett, Amanda M; Kharel, Yugesh; Sunkara, Manjula; Morris, Andrew J; Lynch, Kevin R

    2012-06-15

    Lysophosphatidic acid (LPA) designates a family of bioactive phosphoglycerides that differ in the length and degree of saturation of their radyl chain. Additional diversity is provided by the linkage of the radyl chain to glycerol: acyl, alkyl, or alk-1-enyl. Acyl-LPAs are the predominate species in tissues and biological fluids. Alkyl-LPAs exhibit distinct pharmacodynamics at LPA receptors, potently drive platelet aggregation, and contribute to ovarian cancer aggressiveness. Multiple biosynthetic pathways exist for alkyl-LPA production. Herein we report that diacylglycerol kinases (DGKs) contribute to cell-associated alkyl-LPA production involving phosphorylation of 1-alkyl-2-acetyl glycerol and document the biosynthesis of alkyl-LPA by DGKs in SKOV-3 ovarian cancer cells, specifically identifying the contribution of DGKα. Concurrently, we discovered that treating SKOV-3 ovarian cancer cell with a sphingosine analog stimulates conversion of exogenous 1-alkyl-2-acetyl glycerol to alkyl-LPA, indicating that DGKα contributes significantly to the production of alkyl-LPA in SKOV-3 cells and identifying cross-talk between the sphingolipid and glycerol lipid pathways.

  4. Poly(ethyleneoxide) functionalization through alkylation

    DOEpatents

    Sivanandan, Kulandaivelu; Eitouni, Hany Basam; Li, Yan; Pratt, Russell Clayton

    2015-04-21

    A new and efficient method of functionalizing high molecular weight polymers through alkylation using a metal amide base is described. This novel procedure can also be used to synthesize polymer-based macro-initiators containing radical initiating groups at the chain-ends for synthesis of block copolymers.

  5. Increased valinomycin production in mutants of Streptomyces sp. M10 defective in bafilomycin biosynthesis and branched-chain α-keto acid dehydrogenase complex expression.

    PubMed

    Lee, Dong Wan; Ng, Bee Gek; Kim, Beom Seok

    2015-11-01

    Streptomyces sp. M10 is a valinomycin-producing bacterial strain that shows potent bioactivity against Botrytis blight of cucumber plants. During studies to increase the yield of valinomycin (a cyclododecadepsipeptide) in strain M10, additional antifungal metabolites, including bafilomycin derivatives (macrolide antibiotics), were identified. To examine the effect of bafilomycin biosynthesis on valinomycin production, the bafilomycin biosynthetic gene cluster was cloned from the genome of strain M10, as were two branched-chain α-keto acid dehydrogenase (BCDH) gene clusters related to precursor supply for bafilomycin biosynthesis. A null mutant (M10bafm) of one bafilomycin biosynthetic gene (bafV) failed to produce bafilomycin, but resulted in a 1.2- to 1.5-fold increase in the amount of valinomycin produced. In another null mutant (M10bkdFm) of a gene encoding a subunit of the BCDH complex (bkdF), bafilomycin production was completely abolished and valinomycin production increased fourfold relative to that in the wild-type M10 strain. The higher valinomycin yield was likely the result of redistribution of the metabolic flux from bafilomycin to valinomycin biosynthesis, because the two antibiotics share a common precursor, 2-ketoisovaleric acid, a deamination product of valine. The results show that directing precursor flux toward active ingredient biosynthesis could be used as a prospective tool to increase the competence of biofungicides.

  6. Effects of kinase inhibitors and potassium phosphate (KPi) on site-specific phosphorylation of branched chain. cap alpha. -ketoacid dehydrogenase (BCKDH)

    SciTech Connect

    Kuntz, M.J.; Shimomura, Y.; Ozawa, T.; Harris, R.A.

    1987-05-01

    BCKDH is phosphorylated by a copurifying kinase at two serine residues on the El..cap alpha.. subunit. Phosphorylation of both sites occurs at about the same rate initially, but inactivation is believed associated only with site 1 phosphorylation. The effects of KPi and known inhibitors of BCKDH kinase, ..cap alpha..-chloroisocaproate (CIC) and branched chain ..cap alpha..-ketoacids (BCKA), on the phosphorylation of purified rat liver BCKDH were studied. Site-specific phosphorylation was quantitated by thin-layer electrophoresis of tryptic peptides followed by densitometric scanning of autoradiograms. Addition of 5 mM KPi was found necessary to stabilize the BCKDH activity at 37/sup 0/C. Increasing the KPi to 50 mM dramatically increased the CIC and BCKA inhibition of site 1 and site 2 phosphorylation. The finding of enhanced sensitivity of inhibitors with 50 mM KPi may facilitate identification of physiologically important kinase effectors. Regardless of the KPi concentration, CIC and the BCKA showed much more effective inhibition of site 2 than site 1 phosphorylation. Although site 1 is the primary inactivating site, predominant inhibition of site 2 phosphorylation may provide a means of modulating kinase/phosphatase control of BCKDH activity under steady state conditions.

  7. The synthesis of branched-chain 3'-C-cyanomethyl-2',3'-dideoxy sugar nucleosides of adenine as potential inhibitors of the human immunodeficiency virus.

    PubMed Central

    Halmos, T; Montserret, R; Antonakis, K

    1989-01-01

    Condensation of the 3'-ketonucleoside 4 with diethyl cyanomethylphosphonate by a Wittig reaction afforded, after reduction of the unsaturated branched chain sugar nucleoside 5 with sodium borohydride, a mixture of 9-(2',5'-di-O-t-butyldimethylsilyl-3'-C-cyanomethyl-3'-deoxy-beta-D-ribo - and xylofuranosyl) adenines 6 and 7, which were separated after selective removal of the 5'-O-tBDMS group. Acetylation gave the monoacetylated ribo- and the triacetylated xylo compounds 10 and 11. Desilylation using tetrabutylammonium fluoride afforded the partially protected ribo isomer 12. The same treatment of 11 was accompanied by a N----O transacetylation giving the fully protected xylo compound 13a, from which the 2'-O-acetyl group was selectively removed using hydroxylaminium acetate. Treatment of 12 and 13b with phenoxythiocarbonyl chloride followed by deoxygenation with tributyltin hydride in the presence of azobisisobutyronitrile, and deacetylation in methanol saturated with ammonia afforded 9-(3'-C-cyanomethyl-2',3'-dideoxy-beta-D-erythro-pentofuranosyl) adenine 2 and 9-(3'-C-cyanomethyl-2'3'-dideoxy-beta-D-threo-pentofuranosyl) adenine 3. PMID:2798123

  8. The Refsum disease marker phytanic acid, a branched chain fatty acid, affects Ca2+ homeostasis and mitochondria, and reduces cell viability in rat hippocampal astrocytes.

    PubMed

    Kahlert, Stefan; Schönfeld, Peter; Reiser, Georg

    2005-02-01

    The saturated branched chain fatty acid, phytanic acid, a degradation product of chlorophyll, accumulates in Refsum disease, an inherited peroxisomal disorder with neurological clinical features. To elucidate the pathogenic mechanism, we investigated the influence of phytanic acid on cellular physiology of rat hippocampal astrocytes. Phytanic acid (100 microM) induced an immediate transient increase in cytosolic Ca2+ concentration, followed by a plateau. The peak of this biphasic Ca2+ response was largely independent of extracellular Ca2+, indicating activation of cellular Ca2+ stores by phytanic acid. Phytanic acid depolarized mitochondria without causing in situ swelling of mitochondria. The slow decrease of mitochondrial potential is not consistent with fast and simultaneous opening of the mitochondrial permeability transition pore. However, phytanic acid induced substantial generation of reactive oxygen species. Phytanic acid caused astroglia cell death after a few hours of exposure. We suggest that the cytotoxic effect of phytanic acid seems to be due to a combined action on Ca2+ regulation, mitochondrial depolarization, and increased ROS generation in brain cells.

  9. Rapid and Precise Measurement of Serum Branched-Chain and Aromatic Amino Acids by Isotope Dilution Liquid Chromatography Tandem Mass Spectrometry

    PubMed Central

    Yang, Ruiyue; Dong, Jun; Guo, Hanbang; Li, Hongxia; Wang, Shu; Zhao, Haijian; Zhou, Weiyan; Yu, Songlin; Wang, Mo; Chen, Wenxiang

    2013-01-01

    Background Serum branched-chain and aromatic amino acids (BCAAs and AAAs) have emerged as predictors for the future development of diabetes and may aid in diabetes risk assessment. However, the current methods for the analysis of such amino acids in biological samples are time consuming. Methods An isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) method for serum BCAAs and AAAs was developed. The serum was mixed with isotope-labeled BCAA and AAA internal standards and the amino acids were extracted with acetonitrile, followed by analysis using LC/MS/MS. The LC separation was performed on a reversed-phase C18 column, and the MS/MS detection was performed via the positive electronic spray ionization in multiple reaction monitoring mode. Results Specific analysis of the amino acids was achieved within 2 min. Intra-run and total CVs for the amino acids were less than 2% and 4%, respectively, and the analytical recoveries ranged from 99.6 to 103.6%. Conclusion A rapid and precise method for the measurement of serum BCAAs and AAAs was developed and may serve as a quick tool for screening serum BCAAs and AAAs in studies assessing diabetes risk. PMID:24339906

  10. High-Speed Microdialysis-Capillary Electrophoresis Assays for Measuring Branched Chain Amino Acid Uptake in 3T3-L1 cells.

    PubMed

    Harstad, Rachel K; Bowser, Michael T

    2016-08-16

    We have developed a high-throughput microdialysis-capillary electrophoresis (MD-CE) assay for monitoring branched chain amino acid (BCAA) uptake/release dynamics in 3T3-L1 cells. BCAAs (i.e., isoleucine, leucine, and valine) and their downstream metabolites (i.e., alanine, glutamine, and glutamate) are important indicators of adipocyte lipogenesis. To perform an analysis, amino acids were sampled using microdialysis, fluorescently labeled in an online reaction, separated using CE, and detected using laser-induced fluorescence (LIF) in a sheath flow cuvette. Separation conditions were optimized for the resolution of the BCAAs isoleucine, leucine, and valine, as well as 13 other amino acids, including ornithine, alanine, glutamine, and glutamate. CE separations were performed in <30 s, and the temporal resolution of the online MD-CE assay was <60 s. Limits of detection (LOD) were 400, 200, and 100 nM for isoleucine, leucine, and valine, respectively. MD-CE dramatically improved throughput in comparison to traditional offline CE methods, allowing 8 replicates of 15 samples (i.e., 120 analyses) to be assayed in <120 min. The MD-CE assay was used to assess the metabolism dynamics of 3T3-L1 cells over time, confirming the utility of the assay. PMID:27398773

  11. Valine, a branched-chain amino Acid, reduced HCV viral load and led to eradication of HCV by interferon therapy in a decompensated cirrhotic patient.

    PubMed

    Kawaguchi, Takumi; Torimura, Takuji; Takata, Akio; Satomi, Susumu; Sata, Michio

    2012-09-01

    A decreased serum level of branched-chain amino acid (BCAA) is a distinctive metabolic disorder in patients with liver cirrhosis. Recently, BCAA has been reported to exert various pharmacological activities, and valine, which is a BCAA, has been shown to affect lipid metabolism and the immune system in in vivo experiments. However, the clinical impact of valine supplementation on viral hepatitis C virus (HCV) load has never been reported. Here, we first describe a case of HCV-related advanced liver cirrhosis that was treated by an oral valine agent. The administration of valine resulted in an improvement of fatigue and a reduction in hepatic fibrosis indexes as well as serum α-fetoprotein level. Furthermore, a marked reduction in HCV RNA levels was seen after valine treatment. The patient was then treated by interferon β, resulting in the successful eradication of chronic HCV infection. Thus, valine may be involved in the reduction of HCV viral load and could support a sustained virologic response to interferon therapy. PMID:23185147

  12. Screening of Streptococcus pneumoniae ABC transporter mutants demonstrates that LivJHMGF, a branched-chain amino acid ABC transporter, is necessary for disease pathogenesis.

    PubMed

    Basavanna, Shilpa; Khandavilli, Suneeta; Yuste, Jose; Cohen, Jonathan M; Hosie, Arthur H F; Webb, Alexander J; Thomas, Gavin H; Brown, Jeremy S

    2009-08-01

    Bacterial ABC transporters are an important class of transmembrane transporters that have a wide variety of substrates and are important for the virulence of several bacterial pathogens, including Streptococcus pneumoniae. However, many S. pneumoniae ABC transporters have yet to be investigated for their role in virulence. Using insertional duplication mutagenesis mutants, we investigated the effects on virulence and in vitro growth of disruption of 9 S. pneumoniae ABC transporters. Several were partially attenuated in virulence compared to the wild-type parental strain in mouse models of infection. For one ABC transporter, required for full virulence and termed LivJHMGF due to its similarity to branched-chain amino acid (BCAA) transporters, a deletion mutant (DeltalivHMGF) was constructed to investigate its phenotype in more detail. When tested by competitive infection, the DeltalivHMGF strain had reduced virulence in models of both pneumonia and septicemia but was fully virulent when tested using noncompetitive experiments. The DeltalivHMGF strain had no detectable growth defect in defined or complete laboratory media. Recombinant LivJ, the substrate binding component of the LivJHMGF, was shown by both radioactive binding experiments and tryptophan fluorescence spectroscopy to specifically bind to leucine, isoleucine, and valine, confirming that the LivJHMGF substrates are BCAAs. These data demonstrate a previously unsuspected role for BCAA transport during infection for S. pneumoniae and provide more evidence that functioning ABC transporters are required for the full virulence of bacterial pathogens. PMID:19470745

  13. Relationship between Branched-Chain Amino Acids, Metabolic Syndrome, and Cardiovascular Risk Profile in a Chinese Population: A Cross-Sectional Study

    PubMed Central

    Hu, Wen; Sun, Luning; Gong, Yingyun; Zhou, Ying; Yang, Panpan; Ye, Zhengqin; Fu, Jinxiang; Huang, Aijie; Fu, Zhenzhen; Yu, Weinan; Zhao, Yang

    2016-01-01

    Objective. This study aimed to evaluate the relationship between branched-chain amino acids (BCAAs), metabolic syndrome (MS), and other cardiovascular (CV) risk factors in middle-aged and elderly Chinese population at high risk for the development of cardiovascular disease (CVD). Methods. 1302 subjects were enrolled from the Huai'an Diabetes Prevention Program. Results. BCAAs levels were positively correlated with MS, its components, and CV risk profile. The odds ratio (OR) for MS among subjects in the fourth quartile of BCAAs levels showed a 2.17-fold increase compared with those in the first quartile. BCAAs were independently associated with high Framingham risk score even after adjusting for MS and its components (P < 0.0001). Additionally, the OR for high CV risk was 3.20-fold (P < 0.0001) in participants in the fourth BCAAs quartile with MS compared with participants in the first BCAAs quartile without MS. Conclusions. Increased BCAAs levels are independent risk factors of MS and CVD in addition to the traditional factors in middle-aged and elderly Chinese population. The development of CVD in MS patients with high level BCAAs is accelerated. Intervention studies are needed to investigate whether the strategy of BCAAs reduction has impacts on endpoints in patients with higher CV risk. This study is registered with ChiCTR-TRC-14005029. PMID:27528871

  14. Branched-Chain Amino Acid Supplementation in Combination with Voluntary Running Improves Body Composition in Female C57BL/6 Mice.

    PubMed

    Platt, Kristen M; Charnigo, Richard J; Shertzer, Howard G; Pearson, Kevin J

    2016-01-01

    Exercise is an inexpensive intervention that may be used to reduce obesity and its consequences. In addition, many individuals who regularly exercise utilize dietary supplements to enhance their exercise routine and to accelerate fat loss or increase lean mass. Branched-chain amino acids (BCAAs) are a popular supplement and have been shown to produce a number of beneficial effects in rodent models and humans. Therefore, we hypothesized that BCAA supplementation would protect against high fat diet (HFD)-induced glucose intolerance and obesity in mice with and without access to exercise. We subjected 80 female C57BL/6 mice to a paradigm of HFD feeding, exercise in the form of voluntary wheel running, and BCAA supplementation in the drinking water for 16 weeks (n = 10 per group). Body weight was monitored weekly, while food and water consumption were recorded twice weekly. During the 5th, 10th, and 15th weeks of treatment, glucose tolerance and body composition were analyzed. Exercise significantly improved glucose tolerance in both control-fed and HFD-fed mice. BCAA supplementation, however, did not significantly alter glucose tolerance in any treatment group. While BCAA supplements did not improve lean to fat mass ratio in sedentary mice, it significantly augmented the effects of exercise on this parameter. PMID:26716948

  15. Branched chain amino acids maintain the molecular weight of poly(γ-glutamic acid) of Bacillus licheniformis ATCC 9945 during the fermentation.

    PubMed

    Mitsunaga, Hitoshi; Meissner, Lena; Büchs, Jochen; Fukusaki, Eiichiro

    2016-10-01

    Poly(γ-glutamic acid) mainly produced by Bacillus spp. is an industrially important compound due to several useful features. Among them, molecular weight is an important characteristic affecting on the physical properties such as viscosities and negative charge densities. However, it is difficult to control the molecular size of PGA since it decreases during fermentation. Previous study reported that PGA produced in the media containing different carbon sources such as glucose and glycerol showed differences in molecular weight. Therefore in this study, the effect of carbon source on the PGA molecular weight was examined; with the aim of developing a strategy to maintain the high molecular weight of PGA during fermentation. Our result showed that the weight average molecular weight (Mw) of PGA of Bacillus licheniformis ATCC 9945 cultivated in the media containing PTS-sugars were higher than the medium containing glycerol (non-PTS). The result of metabolome analysis indicated the possibility of CodY (a global regulator protein) activation in the cells cultivated in the media containing PTS-sugars. To mimic this effect, branched-chain amino acids (BCAAs), which are activators of CodY, were added to a medium containing glycerol. As the result, the Mw of PGA in the BCAAs-supplemented media were maintained and high during the early production phase compared to the non BCAAs-supplemented medium. These results indicate that BCAAs can repress the PGA molecular weight reduction during fermentation in B. licheniformis ATCC 9945.

  16. Elimination of infused branched-chain amino-acids from plasma of patients with non-obese type 2 diabetes mellitus.

    PubMed

    Marchesini, G; Bianchi, G P; Vilstrup, H; Capelli, M; Zoli, M; Pisi, E

    1991-04-01

    Increased plasma levels of branched-chain amino-acids (BCAA) have been demonstrated in poorly controlled diabetes mellitus, and related to absolute or relative insulin deficiency. To study the pathogenesis of this alteration, the elimination of BCAA from plasma was measured in 8 patients with non-obese type 2 diabetes mellitus and in 8 age-matched control subjects during steady-state BCAA concentrations induced by a primed-continuous infusion. Fasting BCAA levels were increased by 40-50% in patients with diabetes. The plasma clearances of valine, isoleucine, and leucine, calculated as infusion rate divided by steady-state concentration, were reduced by 20% in diabetics, despite 50% hyperinsulinemia (P < 0.01). Basal BCAA levels and BCAA clearance were negatively correlated (r(2) = 0.46 - 0.56). The endogenous basal appearance rates of BCAA, estimated by the basal concentrations multiplied by the plasma clearances, were normal in diabetics, and there was no difference in the apparent volumes of distribution of BCAA. The increased basal concentration of BCAA in poorly controlled type 2 diabetics (693 [SD 114; n = 8] mumol/l vs 479 [88; n = 8] in controls (P < 0.005) is attributable to changes in plasma clearances, without any change in the efflux of BCAA into plasma. This may be due to insulin resistance.

  17. Relationship between Branched-Chain Amino Acids, Metabolic Syndrome, and Cardiovascular Risk Profile in a Chinese Population: A Cross-Sectional Study.

    PubMed

    Hu, Wen; Sun, Luning; Gong, Yingyun; Zhou, Ying; Yang, Panpan; Ye, Zhengqin; Fu, Jinxiang; Huang, Aijie; Fu, Zhenzhen; Yu, Weinan; Zhao, Yang; Yang, Tao; Zhou, Hongwen

    2016-01-01

    Objective. This study aimed to evaluate the relationship between branched-chain amino acids (BCAAs), metabolic syndrome (MS), and other cardiovascular (CV) risk factors in middle-aged and elderly Chinese population at high risk for the development of cardiovascular disease (CVD). Methods. 1302 subjects were enrolled from the Huai'an Diabetes Prevention Program. Results. BCAAs levels were positively correlated with MS, its components, and CV risk profile. The odds ratio (OR) for MS among subjects in the fourth quartile of BCAAs levels showed a 2.17-fold increase compared with those in the first quartile. BCAAs were independently associated with high Framingham risk score even after adjusting for MS and its components (P < 0.0001). Additionally, the OR for high CV risk was 3.20-fold (P < 0.0001) in participants in the fourth BCAAs quartile with MS compared with participants in the first BCAAs quartile without MS. Conclusions. Increased BCAAs levels are independent risk factors of MS and CVD in addition to the traditional factors in middle-aged and elderly Chinese population. The development of CVD in MS patients with high level BCAAs is accelerated. Intervention studies are needed to investigate whether the strategy of BCAAs reduction has impacts on endpoints in patients with higher CV risk. This study is registered with ChiCTR-TRC-14005029. PMID:27528871

  18. β-Alkyl Elimination: Fundamental Principles and Some Applications.

    PubMed

    O'Reilly, Matthew E; Dutta, Saikat; Veige, Adam S

    2016-07-27

    This review describes organometallic compounds and materials that are capable of mediating a rarely encountered but fundamentally important reaction: β-alkyl elimination at the metal-Cα-Cβ-R moiety, in which an alkyl group attached to the Cβ atom is transferred to the metal or to a coordinated substrate. The objectives of this review are to provide a cohesive fundamental understanding of β-alkyl-elimination reactions and to highlight its applications in olefin polymerization, alkane hydrogenolysis, depolymerization of branched polymers, ring-opening polymerization of cycloalkanes, and other useful organic reactions. To provide a coherent understanding of the β-alkyl elimination reaction, special attention is given to conditions and strategies used to facilitate β-alkyl-elimination/transfer events in metal-catalyzed olefin polymerization, which provide the well-studied examples.

  19. Antioxidant activity of alkyl gallates and glycosyl alkyl gallates in fish oil in water emulsions: relevance of their surface active properties and of the type of emulsifier.

    PubMed

    González, María J; Medina, Isabel; Maldonado, Olivia S; Lucas, Ricardo; Morales, Juan C

    2015-09-15

    The antioxidant activity of gallic acid and a series of alkyl gallates (C4-C18) and glycosylated alkyl gallates (C4-C18) on fish oil-in-water emulsions was studied. Three types of emulsifiers, lecithin, Tween-20 and sodium dodecyl sulphate (SDS) were tested. A nonlinear behavior of the antioxidant activity of alkyl gallates when increasing alkyl chain length was observed for emulsions prepared with lecithin. Medium-size alkyl gallates (C6-C12) were the best antioxidants. In contrast, for emulsions prepared with Tween-20, the antioxidants seem to follow the polar paradox. Glucosyl alkyl gallates were shown previously to be better surfactants than alkyl gallates. Nevertheless, they exhibited a worse antioxidant capacity than their corresponding alkyl gallates, in emulsions prepared with lecithin or Tween-20, indicating the greater relevance of having three OH groups at the polar head in comparison with having improved surfactant properties but just a di-ortho phenolic structure in the antioxidant.

  20. Spontaneous intercalation of long-chain alkyl ammonium into edge-selectively oxidized graphite to efficiently produce high-quality graphene

    PubMed Central

    Wei, Liangming; Wu, Fei; Shi, Diwen; Hu, Changchen; Li, Xiaolin; Yuan, Weien; Wang, Jian; Zhao, Jiang; Geng, Huijuan; Wei, Hao; Wang, Ying; Hu, Nantao; Zhang, Yafei

    2013-01-01

    Mass production of high-quality graphene nanosheets (GNs) is essential for practical applications. We report that oxidation of graphite by low concentration KMnO4 at relatively high temperature (60°C) leads to edge-selectively oxidized graphite (EOG) which preserves the high crystalline graphitic structure on its basal planes while the edges are functionalized by oxygen-containing groups. Long-chain tetradecyl-ammonium salt (C14N+) could be spontaneously intercalated into EOG to form intercalated EOG-C14N+ compounds. Gentle and short-time sonication of EOG-C14N+ in toluene can full exfoliate EOG into edge-oxidized graphene nanosheets (EOGNs) with concentration of 0.67 mg/ml, monolayer population up to 90% and lateral size from 1 μm to >100 μm. The EOG and EOGN films show excellent electrical conductance, which is far superior to their graphene oxide (GO) counterparts. Our method provides an efficient way to produce high-quality GNs, and the resultant EOG also can be directly used for production of multifunctional materials and devices. PMID:24022463

  1. Inhibitory Activities of Alkyl Syringates and Related Compounds on Aflatoxin Production.

    PubMed

    Furukawa, Tomohiro; Iimura, Kurin; Kimura, Taichi; Yamamoto, Toshiyoshi; Sakuda, Shohei

    2016-06-07

    Inhibitors of aflatoxin production of aflatoxigenic fungi are useful for preventing aflatoxin contamination in crops. As methyl syringate weakly inhibits aflatoxin production, aflatoxin production inhibitory activities of additional alkyl syringates with alkyl chains from ethyl to octyl were examined. Inhibitory activity toward aflatoxin production of Aspergillus flavus became stronger as the length of the alkyl chains on the esters became longer. Pentyl, hexyl, heptyl, and octyl syringates showed strong activity at 0.05 mM. Heptyl and octyl parabens, and octyl gallate also inhibited aflatoxin production as strongly as octyl syringate. Alkyl parabens and alkyl gallates inhibit the complex II activity of the mitochondrial respiration chain; thus, whether alkyl syringates inhibit complex II activity was examined. Inhibitory activities of alkyl syringates toward complex II also became stronger as the length of the alkyl chains increased. The complex II inhibitory activity of octyl syringate was comparable to that of octyl paraben and octyl gallate. These results suggest that alkyl syringates, alkyl parabens, and alkyl gallates, including commonly used food additives, are useful for aflatoxin control.

  2. Inhibitory Activities of Alkyl Syringates and Related Compounds on Aflatoxin Production.

    PubMed

    Furukawa, Tomohiro; Iimura, Kurin; Kimura, Taichi; Yamamoto, Toshiyoshi; Sakuda, Shohei

    2016-01-01

    Inhibitors of aflatoxin production of aflatoxigenic fungi are useful for preventing aflatoxin contamination in crops. As methyl syringate weakly inhibits aflatoxin production, aflatoxin production inhibitory activities of additional alkyl syringates with alkyl chains from ethyl to octyl were examined. Inhibitory activity toward aflatoxin production of Aspergillus flavus became stronger as the length of the alkyl chains on the esters became longer. Pentyl, hexyl, heptyl, and octyl syringates showed strong activity at 0.05 mM. Heptyl and octyl parabens, and octyl gallate also inhibited aflatoxin production as strongly as octyl syringate. Alkyl parabens and alkyl gallates inhibit the complex II activity of the mitochondrial respiration chain; thus, whether alkyl syringates inhibit complex II activity was examined. Inhibitory activities of alkyl syringates toward complex II also became stronger as the length of the alkyl chains increased. The complex II inhibitory activity of octyl syringate was comparable to that of octyl paraben and octyl gallate. These results suggest that alkyl syringates, alkyl parabens, and alkyl gallates, including commonly used food additives, are useful for aflatoxin control. PMID:27338472

  3. Inhibitory Activities of Alkyl Syringates and Related Compounds on Aflatoxin Production

    PubMed Central

    Furukawa, Tomohiro; Iimura, Kurin; Kimura, Taichi; Yamamoto, Toshiyoshi; Sakuda, Shohei

    2016-01-01

    Inhibitors of aflatoxin production of aflatoxigenic fungi are useful for preventing aflatoxin contamination in crops. As methyl syringate weakly inhibits aflatoxin production, aflatoxin production inhibitory activities of additional alkyl syringates with alkyl chains from ethyl to octyl were examined. Inhibitory activity toward aflatoxin production of Aspergillus flavus became stronger as the length of the alkyl chains on the esters became longer. Pentyl, hexyl, heptyl, and octyl syringates showed strong activity at 0.05 mM. Heptyl and octyl parabens, and octyl gallate also inhibited aflatoxin production as strongly as octyl syringate. Alkyl parabens and alkyl gallates inhibit the complex II activity of the mitochondrial respiration chain; thus, whether alkyl syringates inhibit complex II activity was examined. Inhibitory activities of alkyl syringates toward complex II also became stronger as the length of the alkyl chains increased. The complex II inhibitory activity of octyl syringate was comparable to that of octyl paraben and octyl gallate. These results suggest that alkyl syringates, alkyl parabens, and alkyl gallates, including commonly used food additives, are useful for aflatoxin control. PMID:27338472

  4. The siloxane bond in contact lens materials: the siloxanyl alkyl methacrylate copolymers.

    PubMed

    Refojo, M F

    1984-11-01

    The siloxanyl alkyl methacrylate copolymers with methyl methacrylate and other components including hydrophilic monomers and crosslinking agents are used to make siloxane methacrylate oxygen-permeable rigid contact lenses. These copolymers contain the element silicon as siloxane bonds in side branches of the main polymer chain, which is made of carbon-to-carbon bonds. The siloxane bonds are the main contributing factor to the oxygen permeability of these materials. Because silicone is not a component of these contact lenses, it is not appropriate to refer to them as silicone methacrylate contact lenses. This paper analyzes data from three fundamental patents and gives the oxygen permeability coefficients of three types of siloxanyl alkyl methacrylate copolymers. In one type the siloxanyl component contains two silicon atoms, in the second type it contains three silicon atoms, and in the third type it contains four silicon atoms. A general relationship, expressed by a power function, is developed between the oxygen permeability coefficients of siloxanyl alkyl methacrylate copolymers and dimethylsilicone rubber and their percent disiloxane or silicon content. PMID:6517434

  5. Effect of chain length and ring size of alkyl and cycloalkyl side-chain substituents upon the biological activity of brassinosteroids. Preparation of novel analogues with activity exceeding that of brassinolide.

    PubMed

    Back, T G; Janzen, L; Nakajima, S K; Pharis, R P

    2000-05-19

    A series of brassinosteroids with different alkyl or cycloalkyl substituents in place of the isopropyl group at C-24 of brassinolide (1) were prepared by the CuCN-catalyzed addition of Grignard reagents to (threo-2R,3S,5alpha,22R,23R,24S)-23,24-epoxy-6, 6-(ethylenedioxy)-2,3-(isopropylidenedioxy)-26, 27-dinorcholestan-22-ol (9), followed by deketalization and Baeyer-Villiger oxidation. Compound 9 was employed as part of a 70:30 threo/erythro mixture of epoxides 9 and 10, from which the erythro-epoxide 10 was recovered intact after the Grignard additions. Thus, the corresponding n-dodecyl, n-hexyl, n-propyl, tert-butyl, cyclohexyl, cyclopentyl, cyclobutyl, and cyclopropyl analogues of brassinolide were obtained. A rearrangement byproduct was observed during the preparation of the cyclopropyl-substituted brassinosteroid when ether was used as the solvent in the Grignard reaction, but could be avoided by the use of THF. A method for recycling the undesired erythro-epoxide 10 was developed on the basis of deoxygenation with tellurium and lithium triethylborohydride. The rice leaf lamina inclination assay was then used to measure the bioactivity of the products. In general, increasing activity was observed as the length or ring size of the C-24 hydrocarbon substituent decreased. The novel cyclobutyl- and cyclopropyl-substituted analogues of brassinolide (1) were ca. 5-7 times as active as 1 and thus appear to be the most potent brassinosteroids reported to date. Further enhancement of the bioactivity of all of the above brassinosteroids, except that of the inactive n-dodecyl derivative, was observed when the brassinosteroid was applied together with an auxin, indole-3-acetic acid (IAA). The synergy between the brassinosteroids and IAA thus increased the bioactivity of the brassinosteroids, including the cyclopropyl and cyclobutyl derivatives, by ca. 1-2 orders of magnitude.

  6. Decarboxylative Alkyl-Alkyl Cross-Coupling Reactions.

    PubMed

    Konev, Mikhail O; Jarvo, Elizabeth R

    2016-09-12

    Alkyl with alkyl: A significant development in alkyl-alkyl cross-coupling reactions, namely the nickel-catalyzed decarboxylative Negishi coupling of N-hydroxyphthalimide esters, was recently reported by Baran and co-workers. This method enables the synthesis of various highly functionalized compounds, including natural product derivatives.

  7. The two active sites in human branched-chain alpha-keto acid dehydrogenase operate independently without an obligatory alternating-site mechanism.

    PubMed

    Li, Jun; Machius, Mischa; Chuang, Jacinta L; Wynn, R Max; Chuang, David T

    2007-04-20

    A long standing controversy is whether an alternating activesite mechanism occurs during catalysis in thiamine diphosphate (ThDP)-dependent enzymes. We address this question by investigating the ThDP-dependent decarboxylase/dehydrogenase (E1b) component of the mitochondrial branched-chain alpha-keto acid dehydrogenase complex (BCKDC). Our crystal structure reveals that conformations of the two active sites in the human E1b heterotetramer harboring the reaction intermediate are identical. Acidic residues in the core of the E1b heterotetramer, which align with the proton-wire residues proposed to participate in active-site communication in the related pyruvate dehydrogenase from Bacillus stearothermophilus, are mutated. Enzyme kinetic data show that, except in a few cases because of protein misfolding, these alterations are largely without effect on overall activity of BCKDC, ruling out the requirement of a proton-relay mechanism in E1b. BCKDC overall activity is nullified at 50% phosphorylation of E1b, but it is restored to nearly half of the pre-phosphorylation level after dissociation and reconstitution of BCKDC with the same phosphorylated E1b. The results suggest that the abolition of overall activity likely results from the specific geometry of the half-phosphorylated E1b in the BCKDC assembly and not due to a disruption of the alternating active-site mechanism. Finally, we show that a mutant E1b containing only one functional active site exhibits half of the wild-type BCKDC activity, which directly argues against the obligatory communication between active sites. The above results provide evidence that the two active sites in the E1b heterotetramer operate independently during the ThDP-dependent decarboxylation reaction. PMID:17329260

  8. Nutritional and clinical evaluation of a modified soy protein with covalently bound branched-chain amino acids in cirrhotic sprague-dawley rats.

    PubMed

    Rodríguez, M F; Wall, A; Kondrup, J; López-Cervantes, G; Calderón de la Barca, A M

    2003-01-01

    Several studies suggested that branched-chain amino acids (BCAA) improve plasma amino acid imbalance as well as protein metabolism in patients with cirrhosis. However, commercial formulas supplemented with free BCAA have their limitations. We evaluated a modified soy protein diet with covalently bound BCAA (diet M) by comparing it with diets based on casein (diet C) or Hepatic Aid II (diet H; commercial formula) as protein sources. After 3 weeks of bile duct obstruction, 24 Sprague-Dawley rats divided into three groups received diets with 9% (w/w) protein/amino acids for 7 days. Nutritional and clinical parameters were determined. Nitrogen balance and weight gain (g)/protein intake (g) with diet M (0.19 +/- 0.31 and 1.33 +/- 1.43 g, respectively) were significantly higher (p < 0.05) than with diet H (-0.34 +/- 0.20 and -0.34 +/- 1.11 g), but comparable to those with diet C (0.04 +/- 0.38 and 0.20 +/- 0.93 g). Animals on diet M had a significantly (p < 0.05) increased plasma BCAA:aromatic amino acid ratio (1.8 +/- 0.3) as compared with those on diets H (1.3 +/- 0.1) and C (0.8 +/- 0.0). There were no significant differences in organ weight or liver function among the groups. We conclude that the BCAA-modified protein is an attractive option in the nutritional support of patients having cirrhosis.

  9. High Leucine Diets Stimulate Cerebral Branched-Chain Amino Acid Degradation and Modify Serotonin and Ketone Body Concentrations in a Pig Model

    PubMed Central

    Wessels, Anna G.; Kluge, Holger; Hirche, Frank; Kiowski, Andreas; Schutkowski, Alexandra; Corrent, Etienne; Bartelt, Jörg; König, Bettina; Stangl, Gabriele I.

    2016-01-01

    In addition to its role as an essential protein component, leucine (Leu) displays several other metabolic functions such as activation of protein synthesis. This property makes it an interesting amino acid for the therapy of human muscle atrophy and for livestock production. However, Leu can stimulate its own degradation via the branched-chain keto acid dehydrogenase complex (BCKDH). To examine the response of several tissues to excessive Leu, pigs were fed diets containing two- (L2) and four-fold (L4) higher Leu contents than the recommended amount (control). We found that the L4 diet led to a pronounced increase in BCKDH activity in the brain (2.5-fold, P < 0.05), liver (1.8-fold, P < 0.05) and cardiac muscle (1.7-fold, P < 0.05), whereas we found no changes in enzyme activity in the pancreas, skeletal muscle, adipose tissue and intestinal mucosa. The L2 diet had only weak effects on BCKDH activity. Both high Leu diets reduced the concentrations of free valine and isoleucine in nearly all tissues. In the brain, high Leu diets modified the amount of tryptophan available: for serotonin synthesis. Compared to the controls, pigs treated with the high Leu diets consumed less food, showed increased plasma concentrations of 3-hydroxybutyrate and reduced levels of circulating serotonin. In conclusion, excessive Leu can stimulate BCKDH activity in several tissues, including the brain. Changes in cerebral tryptophan, along with the changes in amino acid-derived metabolites in the plasma may limit the use of high Leu diets to treat muscle atrophy or to increase muscle growth. PMID:26930301

  10. Activation of mTORC1 by leucine is potentiated by branched-chain amino acids and even more so by essential amino acids following resistance exercise.

    PubMed

    Moberg, Marcus; Apró, William; Ekblom, Björn; van Hall, Gerrit; Holmberg, Hans-Christer; Blomstrand, Eva

    2016-06-01

    Protein synthesis is stimulated by resistance exercise and intake of amino acids, in particular leucine. Moreover, activation of mammalian target of rapamycin complex 1 (mTORC1) signaling by leucine is potentiated by the presence of other essential amino acids (EAA). However, the contribution of the branched-chain amino acids (BCAA) to this effect is yet unknown. Here we compare the stimulatory role of leucine, BCAA, and EAA ingestion on anabolic signaling following exercise. Accordingly, eight trained volunteers completed four sessions of resistance exercise during which they ingested either placebo, leucine, BCAA, or EAA (including the BCAA) in random order. Muscle biopsies were taken at rest, immediately after exercise, and following 90 and 180 min of recovery. Following 90 min of recovery the activity of S6 kinase 1 (S6K1) was greater than at rest in all four trials (Placebo

  11. Intake of branched-chain or essential amino acids attenuates the elevation in muscle levels of PGC-1α4 mRNA caused by resistance exercise.

    PubMed

    Samuelsson, Hedvig; Moberg, Marcus; Apró, William; Ekblom, Björn; Blomstrand, Eva

    2016-07-01

    The transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α is recognized as the master regulator of mitochondrial biogenesis. However, recently a novel isoform, PGC-1α4, that specifically regulates muscle hypertrophy was discovered. Because stimulation of mechanistic target of rapamycin complex 1 (mTORC1) activity is tightly coupled to hypertrophy, we hypothesized that activation of this pathway would upregulate PGC-1α4. Eight male subjects performed heavy resistance exercise (10 × 8-12 repetitions at ∼75% of 1 repetition maximum in leg press) on four different occasions, ingesting in random order a solution containing essential amino acids (EAA), branched-chain amino acids (BCAA), leucine, or flavored water (placebo) during and after the exercise. Biopsies were taken from the vastus lateralis muscle before and immediately after exercise, as well as following 90 and 180 min of recovery. Signaling through mTORC1, as reflected in p70S6 kinase phosphorylation, was stimulated to a greater extent by the EAA and BCAA than the leucine or placebo supplements. Unexpectedly, intake of EAA or BCAA attenuated the stimulatory effect of exercise on PGC-1α4 expression by ∼50% (from a 10- to 5-fold increase with BCAA and EAA, P < 0.05) 3 h after exercise, whereas intake of leucine alone did not reduce this response. The 60% increase (P < 0.05) in the level of PGC-1α1 mRNA 90 min after exercise was uninfluenced by amino acid intake. Muscle glycogen levels were reduced and AMP-activated protein kinase α2 activity and phosphorylation of p38 mitogen-activated protein kinase enhanced to the same extent with all four supplements. In conclusion, induction of PGC-1α4 does not appear to regulate the nutritional (BCAA or EAA)-mediated activation of mTORC1 in human muscle. PMID:27245337

  12. Intake of branched-chain amino acids influences the levels of MAFbx mRNA and MuRF-1 total protein in resting and exercising human muscle.

    PubMed

    Borgenvik, Marcus; Apró, William; Blomstrand, Eva

    2012-03-01

    Resistance exercise and amino acids are two major factors that influence muscle protein turnover. Here, we examined the effects of resistance exercise and branched-chain amino acids (BCAA), individually and in combination, on the expression of anabolic and catabolic genes in human skeletal muscle. Seven subjects performed two sessions of unilateral leg press exercise with randomized supplementation with BCAA or flavored water. Biopsies were collected from the vastus lateralis muscle of both the resting and exercising legs before and repeatedly after exercise to determine levels of mRNA, protein phosphorylation, and amino acid concentrations. Intake of BCAA reduced (P < 0.05) MAFbx mRNA by 30 and 50% in the resting and exercising legs, respectively. The level of MuRF-1 mRNA was elevated (P < 0.05) in the exercising leg two- and threefold under the placebo and BCAA conditions, respectively, whereas MuRF-1 total protein increased by 20% (P < 0.05) only in the placebo condition. Phosphorylation of p70(S6k) increased to a larger extent (∼2-fold; P < 0.05) in the early recovery period with BCAA supplementation, whereas the expression of genes regulating mTOR activity was not influenced by BCAA. Muscle levels of phenylalanine and tyrosine were reduced (13-17%) throughout recovery (P < 0.05) in the placebo condition and to a greater extent (32-43%; P < 0.05) following BCAA supplementation in both resting and exercising muscle. In conclusion, BCAA ingestion reduced MAFbx mRNA and prevented the exercise-induced increase in MuRF-1 total protein in both resting and exercising leg. Further-more, resistance exercise differently influenced MAFbx and MuRF-1 mRNA expression, suggesting both common and divergent regulation of these two ubiquitin ligases.

  13. Branched-chain amino acids increase arterial blood ammonia in spite of enhanced intrinsic muscle ammonia metabolism in patients with cirrhosis and healthy subjects.

    PubMed

    Dam, Gitte; Keiding, Susanne; Munk, Ole Lajord; Ott, Peter; Buhl, Mads; Vilstrup, Hendrik; Bak, Lasse Kristoffer; Waagepetersen, Helle Sønderby; Schousboe, Arne; Møller, Niels; Sørensen, Michael

    2011-08-01

    Branched-chain amino acids (BCAA) are used in attempts to reduce blood ammonia in patients with cirrhosis and intermittent hepatic encephalopathy based on the hypothesis that BCAA stimulate muscle ammonia detoxification. We studied the effects of an oral dose of BCAA on the skeletal muscle metabolism of ammonia and amino acids in 14 patients with cirrhosis and in 7 healthy subjects by combining [(13)N]ammonia positron emission tomography (PET) of the thigh muscle with measurements of blood flow and arteriovenous (A-V) concentrations of ammonia and amino acids. PET was used to measure the metabolism of blood-supplied ammonia and the A-V measurements were used to measure the total ammonia metabolism across the thigh muscle. After intake of BCAA, blood ammonia increased more than 30% in both groups of subjects (both P < 0.05). Muscle clearance of blood-supplied ammonia (PET) was unaffected (P = 0.75), but the metabolic removal rate (PET) increased significantly because of increased blood ammonia in both groups (all P < 0.05). The total ammonia clearance across the leg muscle (A-V) increased by more than 50% in both groups, and the flux (A-V) of ammonia increased by more than 45% (all P < 0.05). BCAA intake led to a massive glutamine release from the muscle (cirrhotic patients, P < 0.05; healthy subjects, P = 0.12). In conclusion, BCAA enhanced the intrinsic muscle metabolism of ammonia but not the metabolism of blood-supplied ammonia in both the patients with cirrhosis and in the healthy subjects.

  14. Content and Composition of Branched-Chain Fatty Acids in Bovine Milk Are Affected by Lactation Stage and Breed of Dairy Cow.

    PubMed

    Bainbridge, Melissa L; Cersosimo, Laura M; Wright, André-Denis G; Kraft, Jana

    2016-01-01

    Dairy products contain bioactive fatty acids (FA) and are a unique dietary source of an emerging class of bioactive FA, branched-chain fatty acids (BCFA). The objective of this study was to compare the content and profile of bioactive FA in milk, with emphasis on BCFA, among Holstein (HO), Jersey (JE), and first generation HO x JE crossbreeds (CB) across a lactation to better understand the impact of these factors on FA of interest to human health. Twenty-two primiparous cows (n = 7 HO, n = 7 CB, n = 8 JE) were followed across a lactation. All cows were fed a consistent total mixed ration (TMR) at a 70:30 forage to concentrate ratio. Time points were defined as 5 days in milk (DIM), 95 DIM, 185 DIM, and 275 DIM. HO and CB had a higher content of n-3 FA at 5 DIM than JE and a lower n-6:n-3 ratio. Time point had an effect on the n-6:n-3 ratio, with the lowest value observed at 5 DIM and the highest at 185 DIM. The content of vaccenic acid was highest at 5 DIM, yet rumenic acid was unaffected by time point or breed. Total odd and BCFA (OBCFA) were higher in JE than HO and CB at 185 and 275 DIM. Breed affected the content of individual BCFA. The content of iso-14:0 and iso-16:0 in milk was higher in JE than HO and CB from 95 to 275 DIM. Total OBCFA were affected by time point, with the highest content in milk at 275 DIM. In conclusion, HO and CB exhibited a higher content of several bioactive FA in milk than JE. Across a lactation the greatest content of bioactive FA in milk occurred at 5 DIM and OBCFA were highest at 275 DIM. PMID:26930646

  15. Content and Composition of Branched-Chain Fatty Acids in Bovine Milk Are Affected by Lactation Stage and Breed of Dairy Cow

    PubMed Central

    Bainbridge, Melissa L.; Cersosimo, Laura M.; Wright, André-Denis G.; Kraft, Jana

    2016-01-01

    Dairy products contain bioactive fatty acids (FA) and are a unique dietary source of an emerging class of bioactive FA, branched-chain fatty acids (BCFA). The objective of this study was to compare the content and profile of bioactive FA in milk, with emphasis on BCFA, among Holstein (HO), Jersey (JE), and first generation HO x JE crossbreeds (CB) across a lactation to better understand the impact of these factors on FA of interest to human health. Twenty-two primiparous cows (n = 7 HO, n = 7 CB, n = 8 JE) were followed across a lactation. All cows were fed a consistent total mixed ration (TMR) at a 70:30 forage to concentrate ratio. Time points were defined as 5 days in milk (DIM), 95 DIM, 185 DIM, and 275 DIM. HO and CB had a higher content of n-3 FA at 5 DIM than JE and a lower n-6:n-3 ratio. Time point had an effect on the n-6:n-3 ratio, with the lowest value observed at 5 DIM and the highest at 185 DIM. The content of vaccenic acid was highest at 5 DIM, yet rumenic acid was unaffected by time point or breed. Total odd and BCFA (OBCFA) were higher in JE than HO and CB at 185 and 275 DIM. Breed affected the content of individual BCFA. The content of iso-14:0 and iso-16:0 in milk was higher in JE than HO and CB from 95 to 275 DIM. Total OBCFA were affected by time point, with the highest content in milk at 275 DIM. In conclusion, HO and CB exhibited a higher content of several bioactive FA in milk than JE. Across a lactation the greatest content of bioactive FA in milk occurred at 5 DIM and OBCFA were highest at 275 DIM. PMID:26930646

  16. Exercise-induced muscle damage is reduced in resistance-trained males by branched chain amino acids: a randomized, double-blind, placebo controlled study

    PubMed Central

    2012-01-01

    Background It is well documented that exercise-induced muscle damage (EIMD) decreases muscle function and causes soreness and discomfort. Branched-chain amino acid (BCAA) supplementation has been shown to increase protein synthesis and decrease muscle protein breakdown, however, the effects of BCAAs on recovery from damaging resistance training are unclear. Therefore, the aim of this study was to examine the effects of a BCAA supplementation on markers of muscle damage elicited via a sport specific bout of damaging exercise in trained volunteers. Methods Twelve males (mean ± SD age, 23 ± 2 y; stature, 178.3 ± 3.6 cm and body mass, 79.6 ± 8.4 kg) were randomly assigned to a supplement (n = 6) or placebo (n = 6) group. The damaging exercise consisted of 100 consecutive drop-jumps. Creatine kinase (CK), maximal voluntary contraction (MVC), muscle soreness (DOMS), vertical jump (VJ), thigh circumference (TC) and calf circumference (CC) were measured as markers of muscle damage. All variables were measured immediately before the damaging exercise and at 24, 48, 72 and 96 h post-exercise. Results A significant time effect was seen for all variables. There were significant group effects showing a reduction in CK efflux and muscle soreness in the BCAA group compared to the placebo (P<0.05). Furthermore, the recovery of MVC was greater in the BCAA group (P<0.05). The VJ, TC and CC were not different between groups. Conclusion The present study has shown that BCAA administered before and following damaging resistance exercise reduces indices of muscle damage and accelerates recovery in resistance-trained males. It seems likely that BCAA provided greater bioavailablity of substrate to improve protein synthesis and thereby the extent of secondary muscle damage associated with strenuous resistance exercise. Clinical Trial Registration Number: NCT01529281. PMID:22569039

  17. High Leucine Diets Stimulate Cerebral Branched-Chain Amino Acid Degradation and Modify Serotonin and Ketone Body Concentrations in a Pig Model.

    PubMed

    Wessels, Anna G; Kluge, Holger; Hirche, Frank; Kiowski, Andreas; Schutkowski, Alexandra; Corrent, Etienne; Bartelt, Jörg; König, Bettina; Stangl, Gabriele I

    2016-01-01

    In addition to its role as an essential protein component, leucine (Leu) displays several other metabolic functions such as activation of protein synthesis. This property makes it an interesting amino acid for the therapy of human muscle atrophy and for livestock production. However, Leu can stimulate its own degradation via the branched-chain keto acid dehydrogenase complex (BCKDH). To examine the response of several tissues to excessive Leu, pigs were fed diets containing two- (L2) and four-fold (L4) higher Leu contents than the recommended amount (control). We found that the L4 diet led to a pronounced increase in BCKDH activity in the brain (2.5-fold, P < 0.05), liver (1.8-fold, P < 0.05) and cardiac muscle (1.7-fold, P < 0.05), whereas we found no changes in enzyme activity in the pancreas, skeletal muscle, adipose tissue and intestinal mucosa. The L2 diet had only weak effects on BCKDH activity. Both high Leu diets reduced the concentrations of free valine and isoleucine in nearly all tissues. In the brain, high Leu diets modified the amount of tryptophan available: for serotonin synthesis. Compared to the controls, pigs treated with the high Leu diets consumed less food, showed increased plasma concentrations of 3-hydroxybutyrate and reduced levels of circulating serotonin. In conclusion, excessive Leu can stimulate BCKDH activity in several tissues, including the brain. Changes in cerebral tryptophan, along with the changes in amino acid-derived metabolites in the plasma may limit the use of high Leu diets to treat muscle atrophy or to increase muscle growth. PMID:26930301

  18. Content and Composition of Branched-Chain Fatty Acids in Bovine Milk Are Affected by Lactation Stage and Breed of Dairy Cow.

    PubMed

    Bainbridge, Melissa L; Cersosimo, Laura M; Wright, André-Denis G; Kraft, Jana

    2016-01-01

    Dairy products contain bioactive fatty acids (FA) and are a unique dietary source of an emerging class of bioactive FA, branched-chain fatty acids (BCFA). The objective of this study was to compare the content and profile of bioactive FA in milk, with emphasis on BCFA, among Holstein (HO), Jersey (JE), and first generation HO x JE crossbreeds (CB) across a lactation to better understand the impact of these factors on FA of interest to human health. Twenty-two primiparous cows (n = 7 HO, n = 7 CB, n = 8 JE) were followed across a lactation. All cows were fed a consistent total mixed ration (TMR) at a 70:30 forage to concentrate ratio. Time points were defined as 5 days in milk (DIM), 95 DIM, 185 DIM, and 275 DIM. HO and CB had a higher content of n-3 FA at 5 DIM than JE and a lower n-6:n-3 ratio. Time point had an effect on the n-6:n-3 ratio, with the lowest value observed at 5 DIM and the highest at 185 DIM. The content of vaccenic acid was highest at 5 DIM, yet rumenic acid was unaffected by time point or breed. Total odd and BCFA (OBCFA) were higher in JE than HO and CB at 185 and 275 DIM. Breed affected the content of individual BCFA. The content of iso-14:0 and iso-16:0 in milk was higher in JE than HO and CB from 95 to 275 DIM. Total OBCFA were affected by time point, with the highest content in milk at 275 DIM. In conclusion, HO and CB exhibited a higher content of several bioactive FA in milk than JE. Across a lactation the greatest content of bioactive FA in milk occurred at 5 DIM and OBCFA were highest at 275 DIM.

  19. Enhanced production of branched-chain amino acids by Gluconacetobacter europaeus with a specific regional deletion in a leucine responsive regulator.

    PubMed

    Akasaka, Naoki; Ishii, Yuri; Hidese, Ryota; Sakoda, Hisao; Fujiwara, Shinsuke

    2014-12-01

    Vinegar with increased amounts of branched-chain amino acids (BCAAs; valine, leucine and isoleucine) is favorable for human health as BCAAs decrease diet-induced obesity and hyperglycemia. To construct Gluconacetobacter europaeus which produces BCAAs, leucine responsive regulator (GeLrp) is focused and two Gelrp mutants were constructed. Wild-type KGMA0119 didn't produce significant amount of valine (0.13 mM) and leucine (0 mM) and strain KGMA7110 which lacks complete Gelrp accumulated valine (0.48 mM) and leucine (0.11 mM) but showed impaired growth, and it was fully restored in the presence of essential amino acids. Strain KGMA7203 was then constructed with a nonsense mutation at codon Trp132 in the Gelrp, which leads a specific deletion at an estimated ligand-sensing region in the C-terminal domain. KGMA7203 produced greater quantities of valine (0.80 mM) and leucine (0.26 mM) and showed the same growth characteristics as KGMA0119. mRNA levels of BCAAs biosynthesis genes (ilvI and ilvC) and probable BCAAs efflux pump (leuE) were determined by quantitative reverse-transcription PCR. Expression rates of ilvI and ilvC in the two Gelrp disruptants were greater than those in KGMA0119. leuE was highly expressed in KGMA7110 only, suggesting that the accumulation in KGMA7110 culture was caused by increased expression of the biosynthesis genes and abnormal enhanced export of amino acids resulting in impaired cell growth. In contrast, KGMA7203 would achieve the high level production through enhanced expression of the biosynthesis genes without enhancing that for the efflux pump. KGMA7203 was considered advantageous for production of vinegar with higher amounts of valine and leucine.

  20. Polyurethane foams based on crude glycerol-derived biopolyols: One-pot preparation of biopolyols with branched fatty acid ester chains and its effects on foam formation and properties

    SciTech Connect

    Li, Cong; Luo, Xiaolan; Li, Tao; Tong, Xinjie; Li, Yebo

    2014-01-01

    Environmentally friendly biopolyols have been produced with crude glycerol as the sole feedstock using a one-pot thermochemical conversion process without the addition of extra catalysts and reagents. Structural features of these biopolyols were characterized by rheology analysis. Rigid polyurethane (PU) foams were obtained from these crude glycerol-based biopolyols and the foaming mechanism was explored. Investigations revealed that partial carbonyl groups hydrogen-bonded with NeH were replaced by aromatic rings after the introduction of branched fatty acid ester chains in the “urea rich” phase, and that distinct microphases had formed in the foams. Studies showed that branched fatty acid ester chains in the biopolyols played an important role in reducing the degree of microphase separation and stabilizing bubbles during foaming processes. PU foams with thermal conductivity comparable to commercial products made from petroleum-based polyols were obtained. These studies show the potential for development of PU foams based on crude glycerol, a renewable resource.

  1. Shoot branching.

    PubMed

    Ward, Sally P; Leyser, Ottoline

    2004-02-01

    The mature form of a plant shoot system is an expression of several genetically controlled traits, many of which are also environmentally regulated. A major component of this architectural variation is the degree of shoot branching. Recent results indicate conserved mechanisms for shoot branch development across the monocots and eudicots. The existence of a novel long-range branch-inhibiting signal has been inferred from studies of branching mutants in pea and Arabidopsis. PMID:14732444

  2. Lipoxygenase inhibitory activity of alkyl protocatechuates.

    PubMed

    Ha, Tae Joung; Shimizu, Kuniyoshi; Kubo, Isao

    2014-09-15

    Alkyl 3,4-dihydroxybenzoates (protocatechuates) inhibited linoleic acid peroxidation catalyzed by soybean lipoxygenase-1 (EC 1.13.11.12, Type 1). Their inhibitory activities displayed a parabolic function of their lipophilicity and maximized with alkyl chain lengths of between C11 and C14. Tetradecanyl protocatechuate exhibited the most potent inhibition with an IC50 of 0.05 μM, followed by dodecyl (lauryl) protocatechuate with an IC50 of 0.06 μM. However, their parent compound, protocatechuic acid, did not show this inhibitory activity up to 200 μM, indicating that the alkyl chain length is significantly related to the inhibition activity. The allosteric (or cooperative) inhibition of soybean lipoxygenase-1 of longer alkyl protocatechuates is reversible but in combination with their iron binding ability to disrupt the active site competitively and to interact with the hydrophobic portion surrounding near the active site (sequential action). In the case of dodecyl protocatechuate, the enzyme quickly binds this protocatechuate and then its dodecyl group undergoes a slow interaction with the hydrophobic domain in close proximity to the active site in the enzyme. The inhibition kinetics analyzed by Lineweaver-Burk plots indicates that octyl protocatechuate is a competitive inhibitor and the inhibition constant (Ki) was obtained as 0.23 μM but dodecyl protocatechuate is a slow binding inhibitor.

  3. Effect of branched-chain amino acid-enriched nutritional supplementation on interferon therapy in Japanese patients with chronic hepatitis C virus infection: a retrospective study

    PubMed Central

    2012-01-01

    Background The aims of this study were to evaluate the effects of nutritional supplementation with branched-chain amino acids (BCAA) with zinc component (Aminofeel®) on adherence to and outcome of therapy in patients treated with interferon (IFN) for chronic hepatitis C and cirrhosis and to determine whether to recommend the supplement. Methods In this retrospective study, 51 patients who received IFN therapy were investigated among 203 consecutive patients who visited our hospital and were advised regarding the potential benefit of taking Aminofeel®. Each patient was free to choose whether to purchase and take Aminofeel®. Results Twenty four patients (group 1-A) took Aminofeel® during standard IFN therapy and 13 (group 1-B) did not. Low-dose, long-term IFN (maintenance) therapy, mainly peglated (Peg)-IFN alpha 2a, was administered to 14 patients who were difficult to treat, because of no effect or harmful side effects with standard IFN therapy, and who had advanced liver fibrosis. Among the 14, 11 patients (group 2-A) took Aminofeel® and 3 (group 2-B) did not. The prevalence of obesity was significantly higher (P=0.04) in group 1-A than in group 1-B. The rate of adherence to IFN therapy was higher in group 1-A (83.3%) than in group 1-B (53.8%, P=0.05). There were no significant differences between the two groups in the rates of sustained virological response (SVR) to IFN therapy. According to multivariate analysis, two factors, SVR and intake of Aminofeel®, were associated with successful adherence to IFN therapy. The adjusted odds ratios for these two factors were 13.25 and 12.59, respectively, and each was statistically significant. The SVR rate of maintenance IFN therapy was in 18.2% group 2-A and 0% in group 2-B. Conclusion Our data show that BCAA intake is useful for adherence to and effect of IFN therapy for patients with chronic hepatitis C. Nutritional supplementation with BCAA seems to be useful for HCV-infected patients receiving IFN therapy

  4. Radioiodinated methyl-branched fatty acids: Evaluation of catabolites formed in vivo

    SciTech Connect

    Knapp, F.F. Jr.; Reske, S.N.; Kirsch, G.; Ambrose, K.R.; Blystone, S.L.; Goodman, M.M.

    1987-01-01

    Radioiodinated terminal iodophenyl-substituted long-chain fatty acids containing either racemic mono-methyl or geminal dimethyl-branching in the alkyl chain have been shown to exhibit delayed myocardial clearance properties which make these agents useful for the SPECT evaluation of myocardial fatty acid uptake patterns. Although the myocardial clearance rate of 15-(p-iodophenyl)-3-R,S- methylpentadecanoic acid (BMIPP) is considerably delayed, in comparison with the IPPA straight-chain analogue, analysis of the radioiodinated lipids present in the outflow tract of isolated rat hearts administered BMIPP have clearly demonstrated the presence of a polar metabolite. The synthesis of ..beta..-hydroxy fatty acids has been developed to allow investigation of the possible formation of ..beta..-hydroxy catabolites in vivo. The preparation of ..beta..-hydroxy BMIPP and ..beta..-hydroxy IPPA are described, and the possible significance of their formation in vivo discussed. 4 figs.

  5. Origin of long-