Science.gov

Sample records for alkyl chain branching

  1. The effect of the cation alkyl chain branching on mutual solubilities with water and toxicities

    PubMed Central

    Kurnia, Kiki A.; Sintra, Tânia E.; Neves, Catarina M. S. S.; Shimizu, Karina; Lopes, José N. Canongia; Gonçalves, Fernando; Ventura, Sónia P. M.; Freire, Mara G.; Santos, Luís M. N. B. F.; Coutinho, João A. P.

    2014-01-01

    The design of ionic liquids has been focused on the cation-anion combinations but other more subtle approaches can be used. In this work the effect of the branching of the cation alkyl chain on the design of ionic liquids (ILs) is evaluated. The mutual solubilities with water and toxicities of a series of bis(trifluoromethylsulfonyl)-based ILs, combined with imidazolium, pyridinium, pyrrolidinium, and piperidinium cations with linear or branched alkyl chains, are reported. The mutual solubility measurements were carried out in the temperature range from (288.15 to 323.15) K. From the obtained experimental data, the thermodynamic properties of the solution (in the water-rich phase) were determined and discussed. The COnductor like Screening MOdel for Real Solvents (COSMO-RS) was used to predict the liquid-liquid equilibrium. Furthermore, molecular dynamic simulations were also carried out aiming to get a deeper understanding of these fluids at the molecular level. The results show that the increase in the number of atoms at the cation ring (from five to six) leads to a decrease in the mutual solubilities with water while increasing their toxicity, and as expected from the well-established relationship between toxicities and hydrophobicities of ILs. The branching of the alkyl chain was observed to decrease the water solubility in ILs, while increasing the ILs solubility in water. The inability of COSMO-RS to correctly predict the effect of branching alkyl chains toward water solubility on them was confirmed using molecular dynamic simulations to be due to the formation of nano-segregated structures of the ILs that are not taken into account by the COSMO-RS model. In addition, the impact of branched alkyl chains on the toxicity is shown to be not trivial and to depend on the aromatic nature of the ILs. PMID:25119425

  2. Photocurrent enhancement from diketopyrrolopyrrole polymer solar cells through alkyl-chain branching point manipulation.

    PubMed

    Meager, Iain; Ashraf, Raja Shahid; Mollinger, Sonya; Schroeder, Bob C; Bronstein, Hugo; Beatrup, Daniel; Vezie, Michelle S; Kirchartz, Thomas; Salleo, Alberto; Nelson, Jenny; McCulloch, Iain

    2013-08-07

    Systematically moving the alkyl-chain branching position away from the polymer backbone afforded two new thieno[3,2-b]thiophene-diketopyrrolopyrrole (DPPTT-T) polymers. When used as donor materials in polymer:fullerene solar cells, efficiencies exceeding 7% were achieved without the use of processing additives. The effect of the position of the alkyl-chain branching point on the thin-film morphology was investigated using X-ray scattering techniques and the effects on the photovoltaic and charge-transport properties were also studied. For both solar cell and transistor devices, moving the branching point further from the backbone was beneficial. This is the first time that this effect has been shown to improve solar cell performance. Strong evidence is presented for changes in microstructure across the series, which is most likely the cause for the photocurrent enhancement.

  3. Activated-Sludge Nitrification in the Presence of Linear and Branched-Chain Alkyl Benzene Sulfonates

    PubMed Central

    Baillod, Charles 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. PMID:5636474

  4. Comparative Study of the Intermolecular Dynamics and Physical Properties of Branched and Linear Alkyl Chain Imidazolium Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Xue, Lianjie; Bardak, Fehmi; Tamas, George; Gurung, Eshan; Quitevis, Edward; Koh, Yung; Simon, Sindee

    2014-03-01

    The optical Kerr effect (OKE) spectra, densities, viscosities, and transition temperatures of 1-alkyl-3-methylimidazolium bis{(trifluoromethane)sulfonyl}amide ionic liquids (ILs) with branched alkyl chains, -Cn-3CH(CH3)2 (branched ILs), were measured and compared to those with linear alkyl chains, -Cn-1CH3 (linear ILs), for n = 3, 4, 5, 6 and 7. The results show that a branched IL has a higher viscosity and transition temperature Tg than the corresponding linear IL with the same n, whereas the densities of each branched/linear IL pair are the same within experimental error. For short alkyl chains (n =3 and 4) the intermolecular part of the OKE spectrum of the branched ILs tends to be narrower and lower in frequency than that of the linear ILs. This suggests that branching softens the intermolecular modes. For long alkyl chains (n =5-7), the difference between the intermolecular spectrum of the branched IL and that of the linear IL with the same n decreases, which indicates that the branching effect becomes smaller when the alkyl chains get longer. This work was supported by NSF grant CHE-1153077.

  5. Effects of straight alkyl chain, extra hydroxylated alkyl chain and branched chain amino acids on gastric emptying evaluated using a non-invasive breath test in conscious rats

    PubMed Central

    Uchida, Masayuki; Kobayashi, Orie; Iwasawa, Kaori; Shimizu, Kimiko

    2016-01-01

    Aim: Some amino acids been known to influence gastric emptying. Thus we have evaluated the effects of straight alkyl chain, extra hydroxylated alkyl chain and branched chain amino acids on gastric emptying. Materials and Methods: Gastric emptying was evaluated in rats after feeding with Racol (nutrient formulae) containing [1-13C] acetic acid. Using a breath test, the content of 13CO2 in their expired air was measured by infrared analyzers. Rats were orally administered with test amino acids, while control rats were administered orally with distilled water. Results: The expired 13CO2 content in the expired air increased with time, peaked after about 30 min and decreased thereafter. Among the amino acids having an alkyl chain, l-serine, l-alanine and l-glycine, significantly decreased the 13CO2 content and Cmax, and delayed Tmax, suggesting inhibition and delay of gastric emptying. AUC120 min values of l-alanine and l-glycine also decreased significantly. l-Threonine significantly decreased 13CO2 content and delayed Tmax, but had no influence on Cmax and AUC120 min values, suggesting a delay of gastric emptying. l-Isoleucine and l-leucine and l-valine significantly decreased 13CO2 content, suggesting inhibition of the gastric emptying, but Cmax, Tmax and AUC120 min values were not significantly affected. Conclusion: The results show that the amino acids used in the present study had different effects on gastric emptying. Moreover, it was found that inhibition and delay of gastric emptying were clearly classifiable by analyzing the change in 13CO2 content of the expired air and the Cmax, Tmax and AUC120 min values. PMID:27169776

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed

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

    2011-03-01

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

  8. Designing greener plasticizers: Effects of alkyl chain length and branching on the biodegradation of maleate based plasticizers.

    PubMed

    Erythropel, Hanno C; Brown, Tobin; Maric, Milan; Nicell, Jim A; Cooper, David G; Leask, Richard L

    2015-09-01

    The ubiquitous presence of the plasticizer di (2-ethylhexyl) phthalate (DEHP) in the environment is of concern due to negative biological effects associated with it and its metabolites. In particular, the metabolite mono (2-ethylhexyl) phthalate (MEHP) is a potential endocrine disruptor. Earlier work had identified the diester di (2-ethylhexyl) maleate (DEHM) as a potential greener candidate plasticizer to replace DEHP, yet its biodegradation rate was reported to be slow. In this study, we modified the side chains of maleate diesters to be linear (i.e., unbranched) alkyl chains that varied in length from ethyl to n-octyl. The plasticization efficiency of these compounds blended into PVC at 29 wt.% increased with the overall length of the molecule, but all compounds performed as well as or better than comparable samples with DEHP. Tests conducted with the equally long DEHM and dihexyl maleate (DHM) showed that branching has no effect on glass transition temperature (Tg) reduction efficiency. Biodegradation experiments with the common soil bacterium Rhodococcus rhodocrous in the presence of the plasticizer showed acceptable hydrolysis rates of maleates with unbranched side chains, while the branched DEHM showed almost no degradation. The addition of hexadecane as auxiliary carbon source improved hydrolysis rates. Temporary buildup of the respective monoester of the compounds were observed, but only in the case of the longest molecule, dioctyl maleate (DOM), did this buildup lead to growth inhibition of the bacteria. Maleates with linear side chains, if designed and tested properly, show promise as potential candidate plasticizers as replacements for DEHP.

  9. Comparative study of the intermolecular dynamics of imidazolium-based ionic liquids with linear and branched alkyl chains: OHD-RIKES measurements.

    PubMed

    Xue, Lianjie; Bardak, Fehmi; Tamas, George; Quitevis, Edward L

    2017-02-08

    This article describes a comparative study of the low-frequency (0-450 cm(-1)) Kerr spectra of the branched 1-(iso-alkyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([(N - 2)mCN-1C1im][NTf2] with N = 3-7) ionic liquids (ILs) and that of the linear 1-(n-alkyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([CNC1im][NTf2] with N = 2-7) ILs. The spectra were obtained by use of femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy (OHD-RIKES). The intermolecular spectrum of a branched IL is similar to that of a linear IL that is of the same alkyl chain length rather than of the same number of carbon atoms in the alkyl chain. This similarity and the lack of a correlation of the first spectral moments and widths of the intermolecular spectra with chain length is mainly attributed to the increase in the dispersion contribution to the total molar cohesive energy being compensated by stretching of the ionic network due to the increasing size of the nonpolar domains, which is dependent only on the length of the alkyl chain.

  10. 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.

  11. 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.

  12. Critical role of alkyl chain branching of organic semiconductors in enabling solution-processed N-channel organic thin-film transistors with mobility of up to 3.50 cm² V(-1) s(-1).

    PubMed

    Zhang, Fengjiao; Hu, Yunbin; Schuettfort, Torben; Di, Chong-an; Gao, Xike; McNeill, Christopher R; Thomsen, Lars; Mannsfeld, Stefan C B; Yuan, Wei; Sirringhaus, Henning; Zhu, Daoben

    2013-02-13

    Substituted side chains are fundamental units in solution processable organic semiconductors in order to achieve a balance of close intermolecular stacking, high crystallinity, and good compatibility with different wet techniques. Based on four air-stable solution-processed naphthalene diimides fused with 2-(1,3-dithiol-2-ylidene)malononitrile groups (NDI-DTYM2) that bear branched alkyl chains with varied side-chain length and different branching position, we have carried out systematic studies on the relationship between film microstructure and charge transport in their organic thin-film transistors (OTFTs). In particular synchrotron measurements (grazing incidence X-ray diffraction and near-edge X-ray absorption fine structure) are combined with device optimization studies to probe the interplay between molecular structure, molecular packing, and OTFT mobility. It is found that the side-chain length has a moderate influence on thin-film microstructure but leads to only limited changes in OTFT performance. In contrast, the position of branching point results in subtle, yet critical changes in molecular packing and leads to dramatic differences in electron mobility ranging from ~0.001 to >3.0 cm(2) V(-1) s(-1). Incorporating a NDI-DTYM2 core with three-branched N-alkyl substituents of C(11,6) results in a dense in-plane molecular packing with an unit cell area of 127 Å(2), larger domain sizes of up to 1000 × 3000 nm(2), and an electron mobility of up to 3.50 cm(2) V(-1) s(-1), which is an unprecedented value for ambient stable n-channel solution-processed OTFTs reported to date. These results demonstrate that variation of the alkyl chain branching point is a powerful strategy for tuning of molecular packing to enable high charge transport mobilities.

  13. Molecular packing of high-mobility diketo pyrrolo-pyrrole polymer semiconductors with branched alkyl side chains.

    PubMed

    Zhang, Xinran; Richter, Lee J; DeLongchamp, Dean M; Kline, R Joseph; Hammond, Matthew R; McCulloch, Iain; Heeney, Martin; Ashraf, Raja S; Smith, Jeremy N; Anthopoulos, Thomas D; Schroeder, Bob; Geerts, Yves H; Fischer, Daniel A; Toney, Michael F

    2011-09-28

    We describe a series of highly soluble diketo pyrrolo-pyrrole (DPP)-bithiophene copolymers exhibiting field effect hole mobilities up to 0.74 cm(2) V(-1) s(-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.

  14. Partial Crystallinity in Alkyl Side Chain Polymers.

    NASA Astrophysics Data System (ADS)

    Sahni, Vasav; Prasad, Shishir; Villate, Johanna; Jiang, Zhang; Sinha, Sunil; Dhinojwala, Ali

    2009-03-01

    Surface freezing is the formation of a crystalline monolayer at the free surface of a melt at a temperature Ts, a few degrees above the bulk freezing temperature, Tb. This effect, i.e. Ts> Tb, common to many chain molecules, is in marked contrast with the surface melting effect, i.e. Ts<=Tb, shown by almost all other materials. Various theoretical and experimental studies have been done to characterize the monolayer formed when the surface freezes before the bulk. We have studied the structure of a novel crystalline surface monolayer on top of a disordered melt of the same material (poly(n-alkyl acrylate)s) using grazing incidence x-ray diffraction. The grazing incidence x-ray diffraction, surface tension, and bulk latent heat results show that there is partial side-chain crystallinity. Also, the surface tension results explain the trend of the difference between the surface order-to-disorder transition temperature and the bulk melting temperature (δT) as a function of side chain length. The behavior of the crystal length, crystal spacing and tilt with varying alkyl chain length and temperature was also studied.

  15. 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.

  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 721.10143 - 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...

  18. 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...

  19. 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...

  20. 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...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Amines, C11-14-branched and linear... 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, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Amines, C11-14-branched and linear... 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. 40 CFR 721.10350 - Amines, C11-14-branched and linear alkyl.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Amines, C11-14-branched and linear... 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...

  4. Alkyl chains acting as entropy reservoir in liquid crystalline materials.

    PubMed

    Sorai, Michio; Saito, Kazuya

    2003-01-01

    The roles played by the conformational disordering of alkyl chains in determining the aggregation states of matter are reviewed for liquid crystalline materials from a thermodynamic perspective. Entropy, which is one of the most macroscopic concepts but which has a clear microscopic meaning, provides crucial microscopic information for complex systems for which a microscopic description is hard to establish. Starting from structural implication by absolute (third-law) entropy for crystalline solids, the existence of successive phase transitions caused by the successive conformational melting of alkyl chains in discotic mesogens is explained. An experimental basis is given for the "quasi-binary picture" of thermotropic liquid crystals, i.e., the highly disordered alkyl chains behave like a second component (solvent). A novel entropy transfer between the "components" of a molecule and the resulting "alkyl chains as entropy reservoir" mechanism are explained for cubic mesogens.

  5. Effects of alkyl chain length on properties of 1-alkyl-3-methylimidazolium fluorohydrogenate ionic liquid crystals.

    PubMed

    Xu, Fei; Matsumoto, Kazuhiko; Hagiwara, Rika

    2010-11-15

    A series of 1-alkyl-3-methylimidazolium fluorohydrogenate salts (C(x)MIm(FH)(2)F, x=8, 10, 12, 14, 16, and 18) have been characterized by thermal analysis, polarized optical microscopy, IR spectroscopy, X-ray diffraction, and anisotropic ionic conductivity measurements. Liquid crystalline mesophases with a smectic A interdigitated bilayer structure are observed from C(10) to C(18), showing a fan-like or focal conic texture. The temperature range of the mesophase increases with the increase in the alkyl chain length (from 10.1 °C for C(10)MIm(FH)(2)F to 123.1 °C for C(18)MIm(FH)(2)F). The distance between the two layers in the smectic structure gradually increases with increasing alkyl chain length and decreases with increasing temperature. Conductivity parallel to the smectic layers is around 10 mS cm(-1) regardless of the alkyl chain length, whereas that perpendicular to the smectic layers decreases with increasing alkyl chain length because of the thicker insulating sheet with the longer alkyl chain.

  6. 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...-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated...

  7. 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...-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated...

  8. 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...-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated...

  9. 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...-alkanoate, aminoalkyl methacrylate and alkyl methacrylate, tert-Bu 2-ethylhexanoperoxoate-initiated...

  10. Detonation Structure Under Chain Branching Kinetics

    NASA Astrophysics Data System (ADS)

    Liang, Z.; Bauwens, L.

    2006-07-01

    Hydrogen-oxygen chemistry is characterized by a chain branching mechanism that yields three explosion limits. While a detailed kinetic scheme appropriate for hydrogen-oxygen should produce correct results, in many circumstances, a simpler yet reasonably realistic model will be warranted. In particular, it is easier to develop a clear understanding of the reaction zone structure using a simpler model, that includes only the key mechanisms. To that effect, we consider a four-step chain branching scheme that exhibits an explosion behavior with three limits, which behaves at least qualitatively like hydrogen chemistry. We focus in particular on the structure of the initiation and chain branching zones, using a combination between numerical simulation and analysis. Numerical simulations using this chemical model show distinctive keystone figures in the flow field, close to observations in hydrogen-oxygen detonation experiments. The structure of the chain branching zone is resolved using a perturbation analysis, which clarifies the differences between explosion and no-explosion regions and allows for an evaluation of the induction length in the steady wave. The analysis assumes both high activation energy and a slow initiation. Three cases are identified, respectively, with pressure and temperature located within the explosion region, close to the explosion limit and within the no-explosion region. The induction length is shorter and the reaction rate is faster by several orders of magnitude in the explosion region.

  11. 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

  12. 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.

  13. 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.

  14. Hyaluronan derivatives: Alkyl chain length boosts viscoelastic behavior to depolymerization.

    PubMed

    Pavan, Mauro; Galesso, Devis; Menon, Giampaolo; Renier, Davide; Guarise, Cristian

    2013-09-12

    Five amide derivatives of Hyaluronic Acid (HA) were synthesized with C8, C12, C15, C16 and C18 linear alkyl-amines. These polymers (Hyadd) were tested against thermal, oxidative and hyaluronidase degradation by means of rheological experiments and SEC analysis and compared to non-modified HA. First of all, no free hexadecylamine was detected in the treated samples, meaning that under these stressing conditions only cleavage of glycosidic bonds occurs. Then, viscoelastic properties were assessed during thermal degradation and their variation as a function of time was expressed by means of a decay constant k(G'): while no significant difference in the decrease rate was observed between Hyadd-C8 and Hyadd-C12, a marked stabilization of viscoelastic properties during thermal treatment was detected for Hyadd-C15, Hyadd-C16 and Hyadd-C18. On the other hand, no difference was observed between the MW decrease rate (kMW decay constant) of HA and Hyadd-C12 to-C18; the depolymerization takes place on the backbone of the polymers independently whether they are derivatized or not, but longer alkyl chains lead to higher viscoelasticity in the depolymerized products. Finally, both oxidative and enzymatic degradation were carried out analyzing the changes in elastic modulus and in dynamic viscosity: once again, the amide side chain came out with similar behavior to chemical cross-linked HA (HBC) and with improved performances respect to linear HA in terms of preservation of viscoelasticity after chain depolymerization.

  15. 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.

  16. Sources and proxy potential of long chain alkyl diols in lacustrine environments

    NASA Astrophysics Data System (ADS)

    Rampen, Sebastiaan W.; Datema, Mariska; Rodrigo-Gámiz, Marta; Schouten, Stefan; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S.

    2014-11-01

    Long chain 1,13- and 1,15-alkyl diols form the base of a number of recently proposed proxies used for climate reconstruction. However, the sources of these lipids and environmental controls on their distribution are still poorly constrained. We have analyzed the long chain alkyl diol (LCD) composition of cultures of ten eustigmatophyte species, with three species from different families grown at various temperatures, to identify the effect of species composition and growth temperature on the LCD distribution. The results were compared with the LCD distribution of sixty-two lake surface sediments, and with previously reported LCD distributions from marine environments. The different families within the Eustigmatophyceae show distinct LCD patterns, with the freshwater family Eustigmataceae most closely resembling LCD distributions in both marine and lake environments. Unlike the other two eustigmatophyte families analyzed (Monodopsidaceae and Goniochloridaceae), C28 and C30 1,13-alkyl diols and C30 and C32 1,15-alkyl diols are all relatively abundant in the family Eustigmataceae, while the mono-unsaturated C32 1,15-alkyl diol was below detection limit. In contrast to the marine environment, LCD distributions in lakes did not show a clear relationship with temperature. The Long chain Diol Index (LDI), a proxy previously proposed for sea surface temperature reconstruction, showed a relatively weak correlation (R2 = 0.33) with mean annual air temperature used as an approximation for annual mean surface temperature of the lakes. A much-improved correlation (R2 = 0.74, p-value <0.001) was observed applying a multiple linear regression analysis between LCD distributions and lake temperatures reconstructed using branched tetraether lipid distributions. The obtained regression model provides good estimates of temperatures for cultures of the family Eustigmataceae, suggesting that algae belonging to this family have an important role as a source for LCDs in lacustrine

  17. 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.

  18. Photoinduced Acrylate Polymerization: Unexpected Reduction in Chain Branching.

    PubMed

    Wenn, Benjamin; Reekmans, Gunter; Adriaensens, Peter; Junkers, Thomas

    2015-08-01

    The branching stemming from midchain radical formation in n-butyl acrylate polymerization is investigated via melt-state (13) C NMR measurements. The dependence of the degree of branching (DB) on the monomer conversion of the system is examined for photoinduced polymerizations, revealing a steady increase in branching with conversion. For polymerization at moderate light intensities, an increase in branching from 0.03% to 0.37% is observed for polymerizations at 60 °C, which is fivefold below the level of branching observed in thermally initiated polymerizations under otherwise identical reaction conditions. The reason for this overall reduction in branching remains momentarily unclear; yet, a strong dependence of branching on light intensity is observed. While polymerization under a 1 W LED lamp results at almost full monomer conversion in branching degrees of 0.22%, polymerization under a 400 W lamp yields 1.81% of chain branches.

  19. Alkyl chain length dependence of the field-effect mobility in novel anthracene derivatives.

    PubMed

    Back, Jang Yeol; An, Tae Kyu; Cheon, Ye Rim; Cha, Hyojung; Jang, Jaeyoung; Kim, Yebyeol; Baek, Yonghwa; Chung, Dae Sung; Kwon, Soon-Ki; Park, Chan Eon; Kim, Yun-Hi

    2015-01-14

    We report six asymmetric alkylated anthracene-based molecules with different alkyl side chain lengths for use in organic field-effect transistors (OFETs). Alkyl side chains can potentially improve the solubility and processability of anthracene derivatives. The crystallinity and charge mobility of the anthracene derivatives may be improved by optimizing the side chain length. The highest field-effect mobility of the devices prepared here was 0.55 cm(2)/(V s), for 2-(p-pentylphenylethynyl)anthracene (PPEA). The moderate side chain length appeared to be optimal for promoting self-organization among asymmetric anthracene derivatives in OFETs, and was certainly better than the short or long alkyl side chain lengths, as confirmed by X-ray diffraction measurements.

  20. Vibrational Spectroscopic Study of Imidazolium Dicationic Ionic Liquids: Effect of Cation Alkyl Chain Length

    NASA Astrophysics Data System (ADS)

    Moumene, T.; Belarbi, E. H.; Haddad, B.; Villemin, D.; Abbas, O.; Khelifa, B.; Bresson, S.

    2016-05-01

    Two new dicationic ionic liquids were synthesized: bis-methyl imidazolium methylidene hexafluorophosphate [M(CH2)IM2 +][2PF 6 - ] and bis-methyl imidazolium propylidene hexafluorophosphate [M(CH2)3IM2 +][2PF 6 - ]. Their structures were identified by H, C, P, F NMR, FTIR/ATR, and FT-Raman spectroscopies in order to study the effect of cation alkyl chain length on vibration behaviors. Several changes were recorded, which were related to alkyl chain length. A frequency shift was observed in some modes while others remained insensitive. A greater number of peaks was found in the FTIR/ATR spectra and the FT-Raman spectra with increasing alkyl chain length, which indicated that chain length influences the N-C connection twisting. More peaks with strong intensity appeared for longer alkyl chain lengths.

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-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...

  2. 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...

  3. 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...

  4. 40 CFR 721.10441 - 1,2-Benzenedicarboxylic acid, di-C7-14-branched and linear alkyl esters.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-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...

  5. Branched-chain amino acid metabolon: interaction of glutamate dehydrogenase with the mitochondrial branched-chain aminotransferase (BCATm).

    PubMed

    Islam, Mohammad Mainul; Nautiyal, Manisha; Wynn, R Max; Mobley, James A; Chuang, David T; Hutson, Susan M

    2010-01-01

    The catabolic pathway for branched-chain amino acids includes deamination followed by oxidative decarboxylation of the deaminated product branched-chain alpha-keto acids, catalyzed by the mitochondrial branched-chain aminotransferase (BCATm) and branched-chain alpha-keto acid dehydrogenase enzyme complex (BCKDC). We found that BCATm binds to the E1 decarboxylase of BCKDC, forming a metabolon that allows channeling of branched-chain alpha-keto acids from BCATm to E1. The protein complex also contains glutamate dehydrogenase (GDH1), 4-nitrophenylphosphatase domain and non-neuronal SNAP25-like protein homolog 1, pyruvate carboxylase, and BCKDC kinase. GDH1 binds to the pyridoxamine 5'-phosphate (PMP) form of BCATm (PMP-BCATm) but not to the pyridoxal 5'-phosphate-BCATm and other metabolon proteins. Leucine activates GDH1, and oxidative deamination of glutamate is increased further by addition of PMP-BCATm. Isoleucine and valine are not allosteric activators of GDH1, but in the presence of 5'-phosphate-BCATm, they convert BCATm to PMP-BCATm, stimulating GDH1 activity. Sensitivity to ADP activation of GDH1 was unaffected by PMP-BCATm; however, addition of a 3 or higher molar ratio of PMP-BCATm to GDH1 protected GDH1 from GTP inhibition by 50%. Kinetic results suggest that GDH1 facilitates regeneration of the form of BCATm that binds to E1 decarboxylase of the BCKDC, promotes metabolon formation, branched-chain amino acid oxidation, and cycling of nitrogen through glutamate.

  6. Gasoline compositions containing branched chain amines or derivatives thereof

    SciTech Connect

    Schuettenberg, A.D.

    1987-02-03

    A detergent additive is described comprising a reaction product of (a) a C/sub 8-30/ branched chain monoamine having at least 7 carbon atoms in a straight chain and (b) a C/sub 1-12/ monocarboxylic acid or ester.

  7. Photoionization of alkylphenothiazines in vesicles: Effects of the alkyl chain length and the vesicle surface charge

    SciTech Connect

    Sakaguchi, Masato; Hu, Ming; Kevan, L. )

    1990-01-25

    The photoionization of alkylphenothiazine (AP = alkylphenothiazine) in vesicles were observed by electron spin resonance (ESR) and electron spin echo modulation (ESEM) methods. Alkylphenothiazine derivatives including sodium 10-methylphenothiazinesulfonate (C{sub 1}PSO{sub 3}Na), sodium 10-dodecylphenothiazinesulfonate (C{sub 12}PSO{sub 3}Na), sodium 3-(10{prime}-phenothiazinyl)propane-1-sulfonate (PC{sub 3}SO{sub 3}Na), sodium 6-(10{prime}-phenothiazinyl)hexane-1-sulfonate (PC{sub 6}SO{sub 3}Na), and sodium 12-(10{prime}-phenothiazinyl)dodecane-1-sulfonate (PC{sub 12}SO{sub 3} Na) were synthesized and used to study the effects of the alkyl chain length, the position of the sulfonate group, and the vesicle surface charge on the photoionization. A single ESR spectrum due to the alkylphenothiazine cation radicals (AP{sup +}) was observed from rapidly frozen AP in dioctadecyldimethylammonium chloride (DODAC) or dihexadecyl phosphate (DHP) vesicles photoirradiated for 10 min with {lambda} > 300 nm. In DODAC vesicles with a positive surface charge, the photoionization yield of PC{sub 12}SO{sub 3}Na with a sulfonate group at the dodecyl chain end is higher than that of C{sub 12}PSO{sub 3}Na with a sulfonate group on the phenothiazine ring. The photoionization yields of AP having the sulfonate group at the alkyl chain end in DODAC vesicles increase with decreasing alkyl chain length. The highest photoionization yield was obtained from PC{sub 3}SO{sub 3}Na, which has the shortest alkyl chain in this study and has the sulfonate group at the end of the propyl chain. The photoionization yield of AP in DHP vesicles with a negative surface charge was not changed by added alkyl chains or the position of the sulfonate group in AP. The results are discussed in terms of the alkyl chain length, the position of the sulfonate group, and the vesicle surface charge.

  8. 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.

  9. Scattering Function for Branched Wormlike Chains.

    PubMed

    Vogtt, Karsten; Beaucage, Gregory; Weaver, Michael; Jiang, Hanqiu

    2015-08-04

    Wormlike or threadlike structures with local cylindrical geometry are abundantly found in nature and technical products. A thorough structural characterization in the bulk for a whole ensemble, however, is difficult. The inherent semiordered nature of the tortuous large-scale structure and especially the quantification of branching renders an assessment difficult. In the present work we introduce a hybrid function expressing the scattering intensities for X-rays, neutrons, or light in the small-angle regime for this system. The function is termed "hybrid" because it employs terms from different approaches. The large-scale structure is described via a Guinier term as well as a concomitant power-law expression in momentum transfer q taken from the so-called unified function. The local cylindrical shape, however, is taken into account through a form factor for cylinders from rigid-body modeling. In principle, the latter form factor can be replaced by an expression for any other regular body so that the new hybrid function is a versatile tool for studying hierarchical structures assembled from uniform subunits. The appropriateness and capability of the new function for cylindrical structures is exemplified using the example of a wormlike micellar system.

  10. Certain Chemical Substances Containing Varying Carbon Chain Lengths (Alkyl Ranges Using the Cx-y Notation) on the TSCA Inventory

    EPA Pesticide Factsheets

    This paper explains the conventions that are applied to certain listings of chemical substances containing ranges of alkyl chain lengths (i.e., carbon chains of varying lengths) for chemical substances on the Toxic Substances Control Act (TSCA)

  11. Interplay between alkyl chain asymmetry and cholesterol addition in the rigid ion pair amphiphile bilayer systems

    NASA Astrophysics Data System (ADS)

    Huang, Fong-yin; Chiu, Chi-cheng

    2017-01-01

    Ion pair amphiphile (IPA), a molecular complex composed of a pair of cationic and anionic surfactants, has been proposed as a novel phospholipid substitute. Controlling the physical stability of IPA vesicles is important for its application developments such as cosmetic and drug deliveries. To investigate the effects of IPA alkyl chain combinations and the cholesterol additive on the structural and mechanical properties of IPA vesicular bilayers, we conducted a series of molecular dynamics studies on the hexadecyltrimethylammonium-dodecylsulfate (HTMA-DS) and dodecyltrimethylammonium-hexadecylsulfate (DTMA-HS) IPA bilayers with cholesterol. We found that both IPA bilayers are in the gel phase at 298 K, consistent with experimental observations. Compared with the HTMA-DS system, the DTMA-HS bilayer has more disordered alkyl chains in the hydrophobic region. When adding cholesterol, it induces alkyl chain ordering around its rigid sterol ring. Yet, cholesterol increases the molecular areas for all species and disturbs the molecular packing near the hydrophilic region and the bilayer core. Cholesterol also promotes the alkyl chain mismatch between the IPA moieties, especially for the DTMA-HS bilayer. The combined effects lead to non-monotonically enhancement of the membrane mechanical moduli for both IPA-cholesterol systems. Furthermore, cholesterol can form H-bonds with the alkylsulfate and thus enhance the contribution of alkylsulfate to the overall mechanical moduli. Combined results provide valuable molecular insights into the roles of each IPA component and the cholesterol on modulating the IPA bilayer properties.

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

    DOE PAGES

    Wang, Zhandong; Zhang, Lidong; Moshammer, Kai; ...

    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

  13. 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.

  14. 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.

  15. 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.

  16. Characterization of esterified cassava starch with long alkyl side chains and different substitution degrees.

    PubMed

    Barrios, Simón E; Giammanco, Giuseppe; Contreras, Jesús M; Laredo, Estrella; López-Carrasquero, Francisco

    2013-08-01

    The present work describes the characterization and thermal properties of hydrophobic starch obtained by the esterification of cassava starch with acyl imidazoles, acid chlorides and methyl ester derivatives of fatty acids with n-alkyl chains with 12-22 carbon atoms, in order to compare the dependence of their properties as a function of the length of the side chain and the methodology used for their synthesis. The n-acyl starches presented degrees of substitution (DS) between 0.06 and 1.2. Most of the derivatives obtained with acyl imidazoles were found to be stable at temperatures up to 300°C, whereas those synthesized with acid chlorides or methyl ester decomposed below. Finally, when the n-acyl starches were substituted with n-alkyl side chains of 16 or more carbon atoms, they were capable to crystallize in separate paraffinic phases independent of the starch backbone.

  17. 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.

  18. Low-band-gap conjugated polymers of dithieno[2,3-b:7,6-b]carbazole and diketopyrrolopyrrole: effect of the alkyl side chain on photovoltaic properties.

    PubMed

    Deng, Yunfeng; Chen, Yagang; Liu, Jian; Liu, Lihui; Tian, Hongkun; Xie, Zhiyuan; Geng, Yanhou; Wang, Fosong

    2013-06-26

    Four donor–acceptor (D–A) conjugated polymers of dithieno[2,3-b;7,6-b]carbazole (DTC) and diketopyrrolopyrrole, which have different alkyls on the nitrogen atom in the DTC unit and are named as P-C8C8, P-C5C5, P-C12, and P-C10, respectively, have been synthesized for studying the effect of the alkyl side chains on the optoelectronic properties of the polymers. All polymers are soluble in various organic solvents and exhibit identical optical band gaps (E(g)(opt)) of ~1.3 eV and highest occupied molecular orbital energy levels of ~−5.1 eV. Organic thin-film transistors and bulk heterojunction polymer solar cells (BHJ PSCs) with phenyl-C(71)-butyric acid methyl ester (PC(71)BM) as the electron-accepting material were fabricated via solution spin-casting. Compared to the polymers substituted by branched alkyl chains, the polymers with straight alkyl chains show higher hole mobility. Of these polymers, P-C10 exhibits the highest field effect mobility up to 0.011 cm(2)/V·s. The alkyl chain on the DTC unit has a strong impact on the film morphology of polymer:PC(71)BM blends. Severe phase separation was found for polymers containing branched alkyl chains, and those with straight alkyl chains formed uniform films featuring fine phase separation. An open-circuit voltage (V(oc)) of 0.72 V, a short-circuit current density (J(sc)) of 13.4 mA/cm(2), a fill factor (FF) of 62%, and a power conversion efficiency (PCE) of 5.9% were demonstrated for BHJ PSCs based on the P-C10:PC(71)BM [1:3 (w/w)] blend film.

  19. 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

  20. 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

  1. U-shaped conformation of alkyl chains bound to a synthetic receptor cucurbit[8]uril.

    PubMed

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

    2011-02-01

    The behavior of a series of alkanes bound to the molecular host cucurbit[8]uril (CB[8]) has been systematically studied by 2D (1)H NMR spectroscopy and isothermal titration calorimetry (ITC). CB[8] and alkyltrimethylammonium (C(m) TA(+), (CH(3))(3)N(+)C(m)H(2m+1), m=6-16) form 1:1 host-guest complexes with a high binding constant (K≈10(6) m(-1)). The shortest hexyl chain of C(6)TA(+) can be fully encapsulated in an extended conformation inside the CB[8] cavity, which is driven by both enthalpy and entropy. However, for the longer aliphatic chains, C(8)-C(16), the long alkyl tails take a U-shaped conformation inside the cavity, and their complexation is dominantly or almost exclusively enthalpy-driven, owing to the increased van der Waals contact between the folded aliphatic chain and the inner wall of the host cavity. As the chain length increases from C(8) to C(16), the ammonium head group of the guests moves away from the portal of CB[8] while the long aliphatic tails maintain the U-shaped conformation inside the cavity. The complexation of C(m)TA(+) with CB[8] follows the enthalpy-entropy compensation rule commonly observed in molecular recognition systems. For example, among the guest molecules, C(12)TA(+) shows the highest enthalpic gain (most favorable), owing to the large van der Waals contact between the guest and the host cavity, and at the same time the most unfavorable entropic contribution, owing to the severe conformational restriction of the U-shaped alkyl chain inside the host. The enthalpy-entropy compensation plot for the complexation suggests large conformational changes of the long alkyl chains and extensive dehydration associated with the inclusion complex formation.

  2. 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.

  3. Metabolically engineered Saccharomyces cerevisiae for branched-chain ester productions.

    PubMed

    Yuan, Jifeng; Mishra, Pranjul; Ching, Chi Bun

    2016-12-10

    Medium branched-chain esters can be used not only as a biofuel but are also useful chemicals with various industrial applications. The development of economically feasible and environment friendly bio-based fuels requires efficient cell factories capable of producing desired products in high yield. Herein, we sought to use a number of strategies to engineer Saccharomyces cerevisiae for high-level production of branched-chain esters. Mitochondrion-based expression of ATF1 gene in a base strain with an overexpressed valine biosynthetic pathway together with expression of mitochondrion-relocalized α-ketoacid decarboxylase (encoded by ARO10) and alcohol dehydrogenase (encoded by ADH7) not only produced isobutyl acetate, but also 3-methyl-1-butyl acetate and 2-methyl-1-butyl acetate. Further segmentation of the downstream esterification step into the cytosol to utilize the cytosolic acetyl-CoA pool for acetyltransferase (ATF)-mediated condensation enabled an additional fold improvement of ester productions. The best titre attained in the present study is 260.2mg/L isobutyl acetate, 296.1mg/L 3-methyl-1-butyl acetate and 289.6mg/L 2-methyl-1-butyl acetate.

  4. Directing alkyl chain ordering of functional phosphorus coupling agents on ZrO2.

    PubMed

    Lomoschitz, Christoph J; Feichtenschlager, Bernhard; Moszner, Norbert; Puchberger, Michael; Müller, Klaus; Abele, Matthias; Kickelbick, Guido

    2011-04-05

    ZrO(2) powder (6.6 m(2)/g) was modified using polymerizable phosphorus-based coupling agents (P-CAs) (i.e., phosphonic acid, phosphoric acid, and bis-phosphonic acid), resulting in densely grafted layers as determined by thermogravimetry and elemental analysis (up to 4.2 molecules/nm(2)). The applied P-CAs contained a methacrylate group, which led to the covalent incorporation of a polymerizable moiety into the grafted layer. To direct the ordering of the alkyl chains in the layer, three different approaches were evaluated with respect to their structure-directing ability by means of FT-IR and nitrogen sorption at 77 K: (i) variation of the chain length, (ii) variation of the anchoring group and (iii) comodification with a defined amount of a nonfunctional phosphonic acid (variation of the functional/nonfunctional acid ratio). It was shown that the chain length and anchoring group size have significant effects on the alkyl chain ordering and morphology of the layer.

  5. 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

  6. 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). ...

  7. Conformation-Specific Spectroscopy of Alkyl Benzyl Radicals: Effects of a Radical Center on the CH Stretch Infrared Spectra of Alkyl Chains

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    An important step in combustion processes is the abstraction of hydrogen to form alkyl benzyl radicals. In this talk we present the results of double resonance spectroscopy methods to explore the conformation-specific infrared spectroscopy of α-methylbenzyl, α-ethylbenzyl, and α-propylbenzyl radicals. A local mode-Hamiltonian model that includes Fermi resonance interactions will be described. This model enables the assignment of the alkyl CH stretch IR spectra of these molecules. This talk will contrast the alkyl chain results to their closed shell analogues, focusing on the the role of the radical site which leads to two important effects. First the CH-stretch frequencies of the β-carbons are shifted by approximately 50 cm-1. Second, internal torsion about the C-C bond between the α-C and β-C atoms modulates these frequency shifts, this producing torsion-vibration mixing. The spectral consequences of this mixing are described.

  8. 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.

  9. 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

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

    PubMed

    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

    2015-09-08

    Although they are 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 β-diol, phthiocerol, with branched-chain fatty acids known as mycocerosates. PapA5 is an acyltransferase implicated in these final reactions. Here, we show that PapA5 is indeed the terminal enzyme in DIM biosynthesis by demonstrating its dual esterification activity and chain-length preference using synthetic alkyl β-diol substrate analogues. By 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 that 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 the regulation of DIM biosynthesis.

  11. 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

    2014-10-07

    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.

  12. 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.

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

    PubMed

    Marshall, Bennett D; Chapman, Walter G

    2013-05-07

    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.

  14. Truncation of the amino terminus of branching enzyme changes its chain transfer pattern.

    PubMed

    Binderup, Kim; Mikkelsen, René; Preiss, Jack

    2002-01-15

    Previous work has reported the production of an Escherichia coli branching enzyme with a 112-residue deletion at the amino terminal by limited proteolysis. Here, we study the chain transfer pattern of this enzyme. Gel-permeation chromatography of in vitro branched amylose shows that the truncated branching enzyme transfers fewer short chains (degree of polymerization [d.p.] <20) and a greater proportion of intermediate size chains (d.p. 30-90) than the native enzyme. High-performance anion-exchange chromatography (HPAEC) of the branching limited alpha-glucan product indicates that the truncated branching enzyme transfers a smaller proportion of chains with d.p. 4-11 and more chains longer than d.p. 12. Also, the genes encoding native or truncated branching enzyme were individually expressed in a branching enzyme-deficient mutant, AC71 (glgB(-)). By HPAEC analysis of the purified alpha-glucans we find that truncated branching enzyme transfers fewer chains of d.p. 5-11 and more chains longer than d.p. 12 relative to the full-length enzyme. These observations allow us to conclude that truncation of the amino-terminal domain has altered the branching pattern of the enzyme. Our results are consistent with the construction of hybrid branching enzymes from the maize isoforms.

  15. Fluoroalkyl and alkyl chains have similar hydrophobicities in binding to the "hydrophobic wall" of carbonic anhydrase.

    PubMed

    Mecinović, Jasmin; Snyder, Phillip W; Mirica, Katherine A; Bai, Serena; Mack, Eric T; Kwant, Richard L; Moustakas, Demetri T; Héroux, Annie; Whitesides, George M

    2011-09-07

    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(2)NSO(2)C(6)H(4)-CONHCH(2)(CX(2))(n)CX(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 entropic contributions to the

  16. Synthesis, nematocidal activity and SAR study of novel difluoromethylpyrazole carboxamide derivatives containing flexible alkyl chain moieties.

    PubMed

    Liu, Xing-Hai; Zhao, Wen; Shen, Zhong-Hua; Xing, Jia-Hua; Xu, Tian-Ming; Peng, Wei-Li

    2017-01-05

    A series of novel difluoromethylpyrazole carboxamides derivatives were synthesized by introduction of flexible alkyl chain. Nematicidal bioassay results showed that some of them exhibited good control efficacy against M. incognita, which indicated that these difluoromethylpyrazole carboxamides derivatives might be potential novel lead compounds for discovery new nematicides. The nematicidal activity was affected by the substituted position in the molecule, especially the substitution group on the alkyl chain. It was found that the compound 6-9 and 6-23 possess about 50% inhibition effect against M. incognita even at 5.0 and 1.0 mg L(-1). Meanwhile, greenhouse field trial showed the nematicidal activity of compound 6-9 is a litter weaker than that of Abamectin. The mammalian toxicology results indicated that compound 6-9 was a low-toxicity and low-sensitive compound. In conclusion compound 6-9 is a potential candidate for further development. In addition, the molecular docking simulations revealed that compounds 6 with a flexible NHCOO show its binding affinities for the acetylcholine receptor (AChR), which may provide useful information for further design novel nematicides.

  17. 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.

  18. Synthesis of branched cores by poly-O-alkylation reaction under phase transfer conditions. A systematic study

    NASA Astrophysics Data System (ADS)

    Landeros, José M.; Silvestre, Hugo A.; Guadarrama, Patricia

    2013-04-01

    In the present paper is described a systematic study of poly-O-alkylation reactions of pentaerythritol (PE) and 1,1,1-tris(hydroxymethyl)ethane (TME) by 1,4 Michael addition, under phase transfer catalysis (PTC), considering the effect of: (1) the organophilicity of PTC (three different catalysts were tested), (2) PTC concentration (from catalytic to equimolar conditions), and (3) the regime of addition of reactants coexisting in the aqueous phase of the heterogeneous reaction system. The less organophilic transfer agent showed the best performance on these reactions. In our case, benzyltriethylammonium chloride (TEBAC) gathers the best features. The presence of NaOH as base, promotes the interfacial mechanism and not the bulk one. Out of the optimal range of concentration of NaOH (35-40%), competition between nucleophiles can occur, due to the saturation of the medium. Regarding the regime of addition of reactants, the scenario where NaOH and TEBAC are less time in contact, favors the formation of the desired products. Finally, the deprotection of tert-butyl groups of the poly-O-alkylated compounds is described, to get branched cores with terminal carboxylic acid groups in good yields (90-94%). Spectroscopic properties, such as IR, 1H and 13C NMR, of the synthesized compounds are also described.

  19. Proton affinity of methyl nitrite and methyl peroxynitrite: implications for measuring branching ratios of alkyl nitrates and nitrites.

    PubMed

    Ravelo, Rose M; Francisco, Joseph S

    2008-08-20

    Geometry optimizations for methyl nitrite and methyl peroxynitrite, along with various protonated isomers for each, have been investigated using ab initio and density functional methods. The lowest energy structure for protonated methyl nitrite is a complex between CH3OH and NO(+). For methyl peroxynitrite, the lowest energy protonated structure is a complex between CH3OOH and NO(+). Their respective proton affinities are estimated to be 195.2 and 195.8 kcal/mol at the QCISD(T)/6-311++G(3df,3pd) level of theory. The results, compared with past studies, suggest an alternative method for directly measuring branching ratios for production of alkyl nitrates and nitrites.

  20. The effect of varying short-chain alkyl substitution on the molar absorptivity and quantum yield of cyanine dyes.

    PubMed

    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.

  1. 40 CFR 721.10024 - 10H-Phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 10H-Phenothiazine, ar-(C9-rich C8-10... New Uses for Specific Chemical Substances § 721.10024 10H-Phenothiazine, ar-(C9-rich C8-10-branched... substance identified as 10H-phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs (PMN P-01-771; CAS...

  2. 40 CFR 721.10024 - 10H-Phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 10H-Phenothiazine, ar-(C9-rich C8-10... New Uses for Specific Chemical Substances § 721.10024 10H-Phenothiazine, ar-(C9-rich C8-10-branched... substance identified as 10H-phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs (PMN P-01-771; CAS...

  3. 40 CFR 721.10024 - 10H-Phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false 10H-Phenothiazine, ar-(C9-rich C8-10... New Uses for Specific Chemical Substances § 721.10024 10H-Phenothiazine, ar-(C9-rich C8-10-branched... substance identified as 10H-phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs (PMN P-01-771; CAS...

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 10H-Phenothiazine, ar-(C9-rich C8-10... New Uses for Specific Chemical Substances § 721.10024 10H-Phenothiazine, ar-(C9-rich C8-10-branched... 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, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false 10H-Phenothiazine, ar-(C9-rich C8-10... New Uses for Specific Chemical Substances § 721.10024 10H-Phenothiazine, ar-(C9-rich C8-10-branched... substance identified as 10H-phenothiazine, ar-(C9-rich C8-10-branched alkyl) derivs (PMN P-01-771; CAS...

  6. Straight-Chain Alkyl Isocyanides Open the Distal Histidine Gate in Crystal Structures of Myoglobin†

    PubMed Central

    Smith, Rober D.; Blouin, George C.; Johnson, Kenneth A.; Phillips, George N.; Olson, John S.

    2014-01-01

    Crystal structures of methyl, ethyl, propyl and butyl isocyanide bound to sperm whale myoglobin (Mb) reveal two major conformations. In the in conformer, His(E7) is in a “closed” position, forcing the ligand alkyl chain to point inward. In the out conformer, His(E7) is in an “open” position, allowing the ligand side chain to point outward. A progressive increase in the population of the out conformer is observed with increasing ligand length in P21 crystals of native Mb at pH 7.0. This switch from in to out with increasing ligand size also occurs in solution as measured by the decrease in the relative intensity of the low (~2075 cm 1) versus high frequency (~2125 cm 1) isocyano bands. In contrast, all four isocyanides in P6 crystals of wild type recombinant Mb occupy the in conformation. However, mutating either His64 to Ala, creating a “hole” to solvent, or Phe46 to Val, freeing rotation of His64, causes bound butyl isocyanide to point completely outward in P6 crystals. Thus, the unfavorable hindrance caused with crowding a large alkyl side chain into the distal pocket appears to be roughly equal to that for pushing open the His(E7) gate and is easily affected by crystal packing. This structural conclusion supports the “side path” kinetic mechanism for O2 release, in which the dissociated ligand first moves toward the protein interior and then encounters steric resistance, which is roughly equal to that for escaping to solvent through the His(E7) channel. PMID:20481504

  7. Effect of surfactant alkyl chain length on soil cadmium desorption using surfactant/ligand systems.

    PubMed

    Shin, Mari; Barrington, Suzelle F; Marshall, William D; Kim, Jin-Woo

    2005-02-01

    The effect of surfactant alkyl chain length on soil Cd desorption was studied using nonionic surfactants of polyethylene oxide (PEO) of PEO chain lengths of 7.5 (Triton X-114), 9.5 (Triton X-100), 30 (Triton X-305), or 40 units (Triton X-405) in combination with the I- ligand. Triplicate 1 g soil samples were equilibrated with 15 ml of surfactant-ligand mixture, at concentrations of 0.025, 0.50 or 0.10, and 0.0, 0.168 or 0.336 mol/l, respectively. After shaking the samples for 24 h, the supernatant fraction was analyzed for Cd content to determine the percent of Cd desorbed from the soil. After five successive washings, 53%, 40% and 25% of Cd had been desorbed by 0.025, 0.050 or 0.10 mol/l of Triton X-114, respectively, in the presence of 0.336 mol/l of I-, whereas with the same conditions, Triton X-100 desorbed 61%, 57% and 56% Cd and either Triton X-305 or Triton X-405 desorbed 51, 40 and 14 to 16% Cd. The most efficient Cd desorption was obtained using 0.025 mol/l Triton X-100 in admixture with 0.336 mol/l I-. Increased surfactant concentration was detrimental to Cd desorption consistent with a process that blocked ligand access to the soil particle surface. After 5 washings,the cumulative cadmium desorption decreased with increasing surfactant alkyl chain length, indicating that the metal-ligand complexes are preferably stabilized by the micelles' hydrophobic octyl phenyl (OP) group rather than by the hydrophilic PEO group. In the absence of ligand, the surfactants alone desorbed less than 1% Cd from the contaminated soil, suggesting that the ligand, rather than the surfactant, extracts the metal, to be subsequently stabilized within the surfactant micelles.

  8. Protein–Ligand Interactions: Thermodynamic Effects Associated with Increasing the Length of an Alkyl Chain

    PubMed Central

    2013-01-01

    Thermodynamic parameters were determined for complex formation between the Grb2 SH2 domain and tripeptides of the general form Ac-pTyr-Xaa-Asn in which the Xaa residue bears a linear alkyl chain varying in length from 1–5 carbon atoms. Binding affinity increases upon adding a methylene group to the Ala derivative, but further chain extension gives no extra enhancement in potency. The thermodynamic signatures of the ethyl and n-propyl derivatives are virtually identical as are those for the n-butyl and n-pentyl analogues. Crystallographic analysis of the complexes reveals a high degree of similarity in the structure of the domain and the bound ligands with the notable exception that there is a gauche interaction in the side chains in the bound conformations of ligands having n-propyl, n-butyl, and n-pentyl groups. However, eliminating this unfavorable interaction by introducing a Z-double bond into the side chain of the n-propyl analogue does not result in an increase in affinity. Increases in the amount of nonpolar surface that is buried upon ligand binding correlate with favorable changes in ΔH°, but these are usually offset by corresponding unfavorable changes in −TΔS°; there is little correlation of ΔCp with changes in the amount of buried nonpolar surface. PMID:24349642

  9. Naturally occurring branched-chain polyamines induce a crosslinked meshwork structure in a giant DNA

    NASA Astrophysics Data System (ADS)

    Muramatsu, Akira; Shimizu, Yuta; Yoshikawa, Yuko; Fukuda, Wakao; Umezawa, Naoki; Horai, Yuhei; Higuchi, Tsunehiko; Fujiwara, Shinsuke; Imanaka, Tadayuki; Yoshikawa, Kenichi

    2016-12-01

    We studied the effect of branched-chain polyamines on the folding transition of genome-sized DNA molecules in aqueous solution by the use of single-molecule observation with fluorescence microcopy. Detailed morphological features of polyamine/DNA complexes were characterized by atomic force microscopy (AFM). The AFM observations indicated that branched-chain polyamines tend to induce a characteristic change in the higher-order structure of DNA by forming bridges or crosslinks between the segments of a DNA molecule. In contrast, natural linear-chain polyamines cause a parallel alignment between DNA segments. Circular dichroism measurements revealed that branched-chain polyamines induce the A-form in the secondary structure of DNA, while linear-chain polyamines have only a minimum effect. This large difference in the effects of branched- and linear-chain polyamines is discussed in relation to the difference in the manner of binding of these polyamines to negatively charged double-stranded DNA.

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10022 Benzenamine, N-phenyl-, ar′-(C9-rich C8-10... chemical substance identified as benzenamine, N-phenyl-, 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, 2012 CFR

    2012-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10022 Benzenamine, N-phenyl-, ar′-(C9-rich C8-10... 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, 2011 CFR

    2011-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10022 Benzenamine, N-phenyl-, ar′-(C9-rich C8-10... chemical substance identified as benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  13. 40 CFR 721.10022 - Benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10022 Benzenamine, N-phenyl-, ar′-(C9-rich C8-10... chemical substance identified as benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  14. 40 CFR 721.10022 - Benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Significant New Uses for Specific Chemical Substances § 721.10022 Benzenamine, N-phenyl-, ar′-(C9-rich C8-10... chemical substance identified as benzenamine, N-phenyl-, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  15. 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.

  16. Growth mechanisms of 2D organic assemblies generated from dialkylated melaminium derivatives: the length difference of the two alkyl chains that matters.

    PubMed

    Xu, Jun; Wu, Guanglu; Wang, Zhiqiang; Zhang, Xi

    2013-08-27

    This research is aimed to understand the growth mechanisms for self-assembly of dialkylated melamine derivatives. The dialkylated melamine derivatives with different alkyl chains (Mela-m-n) are able to self-assemble with hydrochloric acid in dichloromethane to form 2D organic assemblies, exhibiting similar lamellar structures as Mela-n·HCl with identical alkyl chains. The most interesting finding is that the growth mechanism of Mela-n·HCl with identical alkyl chains is revealed to be layer growth, while Mela-m-n·HCl with asymmetric alkyl chains adopts a spiral growth mechanism. The asymmetric alkyl chains in Mela-m-n may lead to the formation of dislocation, which is responsible for the spiral growth mechanism.

  17. 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.

  18. 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.

  19. 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...

  20. 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.

  1. 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.

  2. Production of branched-chain volatile fatty acids by certain anaerobic bacteria.

    PubMed Central

    Allison, M J

    1978-01-01

    Net production of isobutyric acid, isovaleric acid, and 2-methylbutyric acid by cultures of Bacteroides ruminicola and Megasphaera elsdenii on media that contained Trypticase or casein hydrolysate continued (up to 5 days) after growth had ceased. Only trace quantities of these acids were produced in a medium that contained a mixture of amino acids that did not include the branched-chain amino acids. M. elsdenii produced increased quantities of the branched-chain fatty acids in a medium that contained Trypticase when glucose was reduced or eliminated from the culture medium. However, B. ruminicola produced increased quantities of branched-chain fatty acids and of phenylacetic acid from Trypticase when glucose was supplied at 3 mg/ml rather than at 1 mg/ml. Single strains of Streptococcus bovis, Selenomonas ruminantium, Bacteroides amylophilus, and Butyrivibrio fibrisolvens did not produce branched-chain fatty acids. PMID:566082

  3. Long-Chain Alkyl Cyanides: Unprecedented Volatile Compounds Released by Pseudomonas and Micromonospora Bacteria.

    PubMed

    Montes Vidal, Diogo; von Rymon-Lipinski, Anna-Lena; Ravella, Srinivasa; Groenhagen, Ulrike; Herrmann, Jennifer; Zaburannyi, Nestor; Zarbin, Paulo H G; Varadarajan, Adithi R; Ahrens, Christian H; Weisskopf, Laure; Müller, Rolf; Schulz, Stefan

    2017-03-09

    The analysis of volatiles from bacterial cultures revealed long-chain aliphatic nitriles, a new class of natural products. Such nitriles are produced by both Gram-positive Micromonospora echinospora and Gram-negative Pseudomonas veronii bacteria, although the structures differ. A variable sequence of chain elongation and dehydration in the fatty acid biosynthesis leads to either unbranched saturated or unsaturated nitriles with an ω-7 double bond, such as (Z)-11-octadecenenitrile, or methyl-branched unsaturated nitriles with the double bond located at C-3, such as (Z)-13-methyltetradec-3-enenitrile. The nitrile biosynthesis starts from fatty acids, which are converted into their amides and finally dehydrated. The structures and biosyntheses of the 19 naturally occurring compounds were elucidated by mass spectrometry, synthesis, and feeding experiments with deuterium-labeled precursors. Some of the nitriles showed antimicrobial activity, for example, against multiresistant Staphylococcus aureus strains.

  4. 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...

  5. 40 CFR 721.10025 - 10H-Phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 10H-Phenothiazine, ar, arâ²-(C9-rich... Significant New Uses for Specific Chemical Substances § 721.10025 10H-Phenothiazine, ar, ar′-(C9-rich C8-10... chemical substances identified as 10H-phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  6. 40 CFR 721.10025 - 10H-Phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 10H-Phenothiazine, ar, arâ²-(C9-rich... Significant New Uses for Specific Chemical Substances § 721.10025 10H-Phenothiazine, ar, ar′-(C9-rich C8-10... chemical substances identified as 10H-phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  7. 40 CFR 721.10025 - 10H-Phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false 10H-Phenothiazine, ar, arâ²-(C9-rich... Significant New Uses for Specific Chemical Substances § 721.10025 10H-Phenothiazine, ar, ar′-(C9-rich C8-10... chemical substances identified as 10H-phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  8. 40 CFR 721.10025 - 10H-Phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 10H-Phenothiazine, ar, arâ²-(C9-rich... Significant New Uses for Specific Chemical Substances § 721.10025 10H-Phenothiazine, ar, ar′-(C9-rich C8-10... chemical substances identified as 10H-phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  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

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false 10H-Phenothiazine, ar, arâ²-(C9-rich... Significant New Uses for Specific Chemical Substances § 721.10025 10H-Phenothiazine, ar, ar′-(C9-rich C8-10... chemical substances identified as 10H-phenothiazine, ar, ar′-(C9-rich C8-10-branched alkyl) derivs (PMN...

  10. Modeling Radioactive Decay Chains with Branching Fraction Uncertainties

    DTIC Science & Technology

    2013-03-01

    over a range of α and β values that did not overflow Equation ( 20 ). A derivation of all three equations can be found in Appendix B. With a well...This proved that Equation (21) would not overflow while returning an answer that had the same precision as Equation ( 20 ) to 13 digits. The...approximately one month. Another result is that only 20 % of isotopes present at any given time have uncertainty from both half-lives and branching

  11. 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.

  12. A chiroptical switch based on supramolecular chirality transfer through alkyl chain entanglement and dynamic covalent bonding.

    PubMed

    Lv, Kai; Qin, Long; Wang, Xiufeng; Zhang, Li; Liu, Minghua

    2013-12-14

    Chirality transfer is an interesting phenomenon in Nature, which represents an important step to understand the evolution of chiral bias and the amplification of the chirality. In this paper, we report the chirality transfer via the entanglement of the alkyl chains between chiral gelator molecules and achiral amphiphilic Schiff base. We have found that although an achiral Schiff base amphiphile could not form organogels in any kind of organic solvents, it formed co-organogels when mixed with a chiral gelator molecule. Interestingly, the chirality of the gelator molecules was transferred to the Schiff base chromophore in the mixed co-gels and there was a maximum mixing ratio for the chirality transfer. Furthermore, the supramolecular chirality was also produced based on a dynamic covalent chemistry of an imine formed by the reaction between an aldehyde and an amine. Such a covalent bond of imine was formed reversibly depending on the pH variation. When the covalent bond was formed the chirality transfer occurred, when it was destroyed, the transfer stopped. Thus, a supramolecular chiroptical switch is obtained based on supramolecular chirality transfer and dynamic covalent chemistry.

  13. Nanostructure of mixtures of protic ionic liquids and lithium salts: effect of alkyl chain length.

    PubMed

    Méndez-Morales, Trinidad; Carrete, Jesús; Rodríguez, Julio R; Cabeza, Óscar; Gallego, Luis J; Russina, Olga; Varela, Luis M

    2015-02-21

    The bulk structure of mixtures of two protic ionic liquids, propylammonium nitrate and butylammonium nitrate, with a salt with a common anion, is analyzed at room temperature by means of small angle X-ray scattering and classical molecular dynamics simulations. The study of several structural properties, such as density, radial distribution functions, spatial distribution functions, hydrogen bonds, coordination numbers and velocity autocorrelation functions, demonstrates that increasing the alkyl chain length of the alkylammonium cation results in more segregated, better defined polar and apolar domains, the latter having a larger size. This increase, ascribed to the erosion of the H-bond network in the ionic liquid polar regions as salt is added, is confirmed by means of small angle X-ray scattering measurements, which show a clear linear increase of the characteristic spatial sizes of the studied protic ionic liquids with salt concentration, similar to that previously reported for ethylammonium nitrate (J. Phys. Chem. B, 2014, 118, 761-770). In addition, larger ionic liquid cations lead to a lower degree of hydrogen bonding and to more sparsely packed three-dimensional structures, which are more easily perturbed by the addition of lithium salts.

  14. 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.

  15. 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.

  16. 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.

  17. Synthesis and evaluation of tamoxifen derivatives with a long alkyl side chain as selective estrogen receptor down-regulators.

    PubMed

    Shoda, Takuji; Kato, Masashi; Harada, Rintaro; Fujisato, Takuma; Okuhira, Keiichiro; Demizu, Yosuke; Inoue, Hideshi; Naito, Mikihiko; Kurihara, Masaaki

    2015-07-01

    Estrogen receptors (ERs) play a major role in the growth of human breast cancer cells. An antagonist that acts as not only an inhibitor of ligand binding but also an inducer of the down-regulation of ER would be useful for the treatment for ER-positive breast cancer. We previously reported the design and synthesis of a selective estrogen receptor down-regulator (SERD), (E/Z)-4-(1-{4-[2-(dodecylamino)ethoxy]phenyl}-2-phenylbut-1-en-1-yl)phenol (C12), which is a tamoxifen derivative having a long alkyl chain on the amine moiety. This compound induced degradation of ERα via a proteasome-dependent pathway and showed an antagonistic effect in MCF-7 cells. With the aim of increasing the potency of SERDs, we designed and synthesized various tamoxifen derivatives that have various lengths and terminal groups of the long alkyl side chain. During the course of our investigation, C10F having a 10-fluorodecyl group on the amine moiety of 4-OHT was shown to be the most potent compound among the tamoxifen derivatives. Moreover, computational docking analysis suggested that the long alkyl chain interacted with the hydrophobic region on the surface of the ER, which is a binding site of helix 12 and coactivator. These results provide useful information to develop promising candidates as SERDs.

  18. Effects of tethering alkyl chains for amphiphilic ruthenium complex dyes on their adsorption to titanium oxide and photovoltaic properties.

    PubMed

    Ni, Jen-Shyang; Hung, Chun-Yi; Liu, Ken-Yen; Chang, Yu-Hsun; Ho, Kuo-Chuan; Lin, King-Fu

    2012-11-15

    Ruthenium (II) complex dye, Ru(4,4'-dicarboxyl-2,2'-bipyridine)(4-nonyl-2,2'-bipyridine) (NCS)(2), (denoted as RuC9) tethering single alkyl chain was synthesized and well characterized. Its adsorption behavior onto the mesoporous TiO(2) and photovoltaic properties were compared with Z907 which has similar chemical structure but tethers two alkyl chains. RuC9 dyes tend to aggregate into vesicles in the acetonitrile/t-butanol co-solvent as a result of the amphiphilic structure, whereas Z907 dyes aggregate into lamellae. The dye-sensitized solar cell (DSSC) with RuC9 dye showed higher short-circuit photocurrent than that with Z907, attributing to its higher molar optical extinction coefficient and more adsorption amount onto the mesoporous TiO(2). However, the DSSC with Z907 dye has higher open-circuit photovoltage and power conversion efficiency, presumably due to the fact that Z907 with more alkyl chains formed a molecular layer with higher hydrophobicity. It reduced the charge recombination in the interface between the dye-sensitized mesoporous TiO(2) and electrolyte as verified by the electrochemical impedance spectroscopy and intensity modulated photocurrent and photovoltage spectroscopies.

  19. 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.

  20. Identification and quantification of even and odd chained 5-n alkylresorcinols, branched chain-alkylresorcinols and methylalkylresorcinols in Quinoa (Chenopodium quinoa).

    PubMed

    Ross, Alastair B; Svelander, Cecilia; Karlsson, Göran; Savolainen, Otto I

    2017-04-01

    Quinoa is a pseudocereal grown in the Andean region of South America that is of increasing interest worldwide as an alternative staple food. We have detected a complex mixture of both odd- and even-alkyl chain alkylresorcinols (AR), branched-chain alkylresorcinols (bcAR) and methylalkylresorcinols (mAR) in ethyl acetate extracts of quinoa. We quantified the content of AR in 17 commercial samples of quinoa, and found that the mean±SD content of AR was 58±16μg/g, bcAR was 182±52μg/g, and mAR was 136±40μg/g. AR from quinoa could also be detected in plasma after eating quinoa, indicating that some of these unique AR could be used as biomarkers of quinoa intake in humans. Further work is required to understand the role of these ARs in the quinoa plant and whether any of the novel ARs may be of particular interest in human nutrition.

  1. [Intermittent branched--chain ketoacidurie in ketotic hypoglycemia: investigations to localize the biochemical defect (author's transl)].

    PubMed

    Held, K R; Sternowsky, H J; Singh, S; Plettner, C; Grüttner, R

    1976-02-01

    We are reporting a girl aged eight years with ketotic hypoglycemia, mental deficiency and retarded motor and somatic development. Investigation of plasma amino acid concentrations during a spontaneous hypoglycemia revealed an increase in the branched-chain amino acids valine (4.1), leucine (7.8) and isoleucine (1.7 mg/100 ml), while alanine was decreased (1.2 mg/100 ml) and ketonuria was present. The determination of the branched-chain ketoacid decarboxylase in leukocytes showed a decrease of approximately 50% of normal for alpha-ketoisocaproic acid (KIC) as substrate, whereas values for alpha-ketoisovaleric acid (KIVA) and alpha-keto-beta-methylvaleric acid (MEVA) were normal. In fibroblasts activities for all three substrates were in the normal range. Intermittend maple-syrup-urine disease was excluded by oral loading tests with the branched-chain amino acids and with an isocaloric, high-protein diet. Impairment of oxydative decarboxylation of leucine, valine, and isoleucine secondary to increased ketogenesis may play an etiologic role in ketotic hypoglycemia, since we observed, by gaschromatographic analysis, an increase in the urinary excretion of KIVA (5.5 mumol/h), KIC (29.4), and MEVA (47.9) after a provocative test with an isocaloric ketogenic diet for 36 hrs. The significance of branched-chain hyperaminoacidemia and branched chain alpha-ketoaciduria is discussed in this context.

  2. 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.

  3. Generating variable birdsong syllable sequences with branching chain networks in avian premotor nucleus HVC

    NASA Astrophysics Data System (ADS)

    Jin, Dezhe Z.

    2009-11-01

    Songs of songbird species such as Bengalese finch consist of sequences of syllables. While syllables are temporally stereotypical, syllable sequences can vary and follow complex, probabilistic transition rules. Recent experiments and computational models suggest that a syllable is encoded in a chain network of projection neurons in premotor nucleus HVC (proper name). Precisely timed spikes propagate along the chain, driving vocalization of the syllable through downstream nuclei. However, the neural basis of the probabilistic transitions between the syllables is not understood. Here we propose that variable syllable sequences are generated through spike propagations in a network in HVC in which the syllable-encoding chain networks are connected into a branching chain pattern. The neurons mutually inhibit each other through the inhibitory HVC interneurons, and are driven by external inputs from nuclei upstream of HVC. At a branching point that connects the final group of a chain to the first groups of several chains, the spike activity selects one branch to continue the propagation. The selection is probabilistic, and is due to the winner-take-all mechanism mediated by the inhibition and noise. The transitions between the chains are Markovian. If the same syllable can be driven by multiple chains, the generated syllable sequences are statistically described by partially observable Markov models. We suggest that the syntax of birdsong syllable sequences is embedded in the connection patterns of HVC projection neurons.

  4. Systematic investigation of zinc aminoalkylphosphonates: influence of the alkyl chain lengths on the structure formation.

    PubMed

    Schmidt, Corinna; Stock, Norbert

    2012-03-05

    With the high-throughput (HT) methodology, the bifunctional aminoalkylphosphonic acids (AAPA) linker molecules 2-aminoethyl- (AEPA), 3-aminopropyl- (APPA), and 4-aminobutylphosphonic acid (ABPA) [HO(3)P-C(n)H(2n)-NH(2) (n = 2-4)] and zinc nitrate were used to synthesize new metal phosphonates in order to investigate the influence of the alkyl chain length on the structure formation. The systematic investigations led to one known (ZnO(3)PC(2)H(4)NH(2)) and six new compounds: one using AEPA, three using APPA, and two using ABPA. The crystal structures of five compounds were determined by single crystal X-ray diffraction, using X-ray powder diffraction (XRPD) data as well as structure modeling employing force field methods. For compound 1, Zn(O(3)P-C(2)H(4)-NH(3))(NO(3))(H(2)O) (monoclinic, Cc, a = 4.799(1) Å, b = 29.342(6) Å, c = 5.631(1) Å, β = 91.59(3)°, V = 792.7(3) Å(3), Z = 4), and compound 2, Zn(2)(OH)(O(3)P-C(3)H(6)-NH(3))(NO(3)) (monoclinic, P2/c, a = 12.158(2) Å, b = 5.0315(10) Å, c = 13.952(3) Å, β = 113.23(3)°, V = 784.3(3) Å(3), Z = 2), the structures were determined using single crystal X-ray diffraction data. The crystal structures of [Zn(O(3)P-C(3)H(6)-NH(2))]·H(2)O (3) (monoclinic, P2(1)/c, a = 9.094(2) Å, b = 5.0118(7) Å, c = 16.067(4) Å, β = 90.38(2)°, V = 732.3(2) Å(3), Z = 4) and Zn(O(3)P-C(4)H(8)-NH(2)) (5) (monoclinic, P2(1)/c, a = 8.570(7) Å, b = 8.378(4) Å, c = 9.902(6) Å, β = 90.94(5)°, V = 710.9(8) Å(3), Z = 4) were determined using XRPD data. The structural model for compound 6, Zn(O(3)P-C(4)H(8)-NH(3))(NO(3))(H(2)O), was established using lattice parameters from XRPD data and following crystal structure modeling employing force field methods. The structures depend strongly on the alkyl chain length n. For n = 2 and 4 isoreticular compounds are observed, while n = 3 leads to new structures. Larger amounts of all compounds were obtained employing scale-up syntheses in a conventional oven as well as in a microwave

  5. Quantum state-resolved molecular scattering of NO (2Π1 /2) at the gas-[Cnmim][Tf2N] room temperature ionic liquid interface: Dependence on alkyl chain length, collision energy, and temperature

    NASA Astrophysics Data System (ADS)

    Zutz, Amelia; Nesbitt, David J.

    2016-10-01

    Room temperature ionic liquids (RTILs) represent a promising class of chemically tunable, low vapor pressure solvents with myriad kinetic applications that depend sensitively on the nature of gas-molecule interactions at the liquid surface. This paper reports on rovibronically inelastic dynamics at the gas-RTIL interface, colliding supersonically cooled hyperthermal molecular beams of NO (1/2 2Π, N = 0) from 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (or [Cnmim][Tf2N]) and probing the scattered NO molecules via laser induced fluorescence (LIF) from the A(2Σ ) state. Specifically, inelastic energy transfer into NO rovibrational and electronic degrees of freedom is explored as a function of RTIL alkyl chain length (n), incident collision energy (Einc) and surface temperature (Ts). At low collision energies (Einc = 2.7(9) kcal/mol), the scattered NO molecules exhibit a rotational temperature (Trot) systematically colder than Ts for all chain lengths, which signals the presence of non-equilibrium dynamics in the desorption channel. At high collision energies (Einc = 20(2) kcal/mol), microscopic branching into trapping/desorption (TD) and impulsive scattering (IS) pathways is clearly evident, with the TD fraction (α ) exhibiting a step-like increase between short (n = 2, 4) and long (n = 8, 12, 16) alkyl chains consistent with theoretical predictions. For all hydrocarbon chain lengths and RTIL temperature conditions, NO rotational excitation in the IS channel yields hyperthermal albeit Boltzmann-like distributions well described by a "temperature" (TIS = 900 -1200 K) that decreases systematically with increasing n. Non-adiabatic, collision induced hopping between ground and excited spin-orbit states is found to be independent of RTIL alkyl chain length and yet increase with collision energy. The scattering data confirm previous experimental reports of an enhanced presence of the alkyl tail at the gas-RTIL interface with increasing n, as well as

  6. Effect of maternal fasting on ovine fetal and maternal branched-chain amino acid transaminase activities.

    PubMed

    Liechty, E A; Barone, S; Nutt, M

    1987-01-01

    Activities of branched-chain amino acid transaminase were assayed in maternal skeletal muscle, liver and fetal skeletal muscle, cardiac muscle, liver, kidney and placenta obtained from fed and 5-day-fasted late gestation ewes. Very high activities were found in placenta; fetal skeletal muscle also had high activity. Fetal brain had intermediate activity, followed by cardiac muscle and kidney. Fetal liver possessed negligible activity. Activities were low in both maternal liver and skeletal muscle. Trends were seen for fasting to increase activities in fetal placenta, skeletal muscle, brain, kidney, heart and maternal liver, but these changes were statistically significant only for fetal brain and placental tissue. Fetal skeletal muscle activity was 100 times that of maternal skeletal muscle. These data imply differences in the metabolism of the branched-chain amino acids by fetal and adult ruminants and expand the thesis that branched-chain amino acids are important to the metabolism of the ovine fetus.

  7. Effects of carbon atom parity and alkyl side chain length on the crystallization and morphology of biscarbamates, a set of model compounds for polyurethanes.

    PubMed

    Khan, Mostofa Kamal; Sundararajan, Pudupadi R

    2011-07-14

    Solid state morphology and crystallization behavior of a homologous series of biscarbamate molecules having varying alkyl side chain lengths with different carbon atom parity were investigated. These are model compounds for polyurethanes. We synthesized a set of biscarbamates with double hydrogen bonding motifs separated by a (CH(2))(6) spacer and with alkyl side chains of various lengths ranging from C(3) to C(18) at the ends. Thermal analysis showed an odd-even alternation in their melting temperatures and heats of fusion, with the odd number of carbon atoms in the side chain having higher melting temperatures and heats of fusion than the even numbered ones, in contrast to the case of n-alkanes. The effect of carbon atom parity in the alkyl side chains on the spherulite size, spherulite growth rate, and isothermal crystallization kinetics was studied. Although the spherulite size increases with the alkyl side chain length, the maximum is seen at an intermediate length and not with a short or long alkyl chain for both the odd and even series. Along this series of molecules, a maximum in spherulite size, spherulite growth rate, and rate of crystallization is seen for C(7)C(6) (odd series) and C(8)C(6) (even series) biscarbamates. There is a significant difference in spherulite size with respect to carbon atom parity in the alkyl side chains as well as sample preparation protocol. Hence the length of the alkyl side chain, carbon atom parity in the alkyl side chains, and the sample preparation protocol (i.e., quenching versus slow cooling) play an important role in the morphology of these molecules. We rationalize this behavior with the relative contributions of hydrogen bonding and van der Waals forces as discerned from IR spectroscopy. While the van der Waals interaction increases with the alkyl side chain length in this series, the hydrogen bond contribution remains invariant. The rate of crystallization follows the trend seen with the spherulitic growth. The

  8. Structure-activity relationships of alkylxanthines: alkyl chain elongation at the N1- or N7-position decreases cardiotonic activity in the isolated guinea pig heart.

    PubMed

    Sanae, F; Ohmae, S; Kurita, M; Sawanishi, H; Takagi, K; Miyamoto, K

    1995-10-01

    Relationships between the alkyl substitutions (C1-C6) and cardiac inotropic activities of xanthine derivatives were studied in isolated guinea pig heart muscles. Most of the alkylxanthines exhibited positive inotropic activity on the left atrium, which was increased with an elongation of alkyl chain at the N3-position but decreased by substitution of a long alkyl group at the N1- or N7-position of the xanthine skeleton. Although positive inotropic activity in the right ventricular papillary muscle was also increased by longer alkyl groups at the N3-position, the inotropic activity became negative with an increment in alkyl chain length at the N1- or N7-position. The positive inotropic activity of alkylxanthines was correlated with their inhibitory activity on the phosphodiesterase (PDE) III isoenzyme. Adenosine A1 antagonism and PDE IV inhibitory activity were also partly associated with the inotropic activity because H-89, an inhibitor of cyclic AMP-dependent protein kinase, diminished the positive inotropic action and potentiated the negative inotropic action. These results indicate that the positive inotropic activity of alkylxanthines becomes weak with elongation of alkyl chains at the N1- and N7-positions; In particular, xanthines having two long alkyl chains show a negative inotropic activity on the right ventricular papillary muscle, an effect that could not be elucidated from their cyclic AMP-dependent action.

  9. Water-mediated recognition of simple alkyl chains by heart-type fatty-acid-binding protein.

    PubMed

    Matsuoka, Shigeru; Sugiyama, Shigeru; Matsuoka, Daisuke; Hirose, Mika; Lethu, Sébastien; Ano, Hikaru; Hara, Toshiaki; Ichihara, Osamu; Kimura, S Roy; Murakami, Satoshi; Ishida, Hanako; Mizohata, Eiichi; Inoue, Tsuyoshi; Murata, Michio

    2015-01-26

    Long-chain fatty acids (FAs) with low water solubility require fatty-acid-binding proteins (FABPs) to transport them from cytoplasm to the mitochondria for energy production. However, the precise mechanism by which these proteins recognize the various lengths of simple alkyl chains of FAs with similar high affinity remains unknown. To address this question, we employed a newly developed calorimetric method for comprehensively evaluating the affinity of FAs, sub-Angstrom X-ray crystallography to accurately determine their 3D structure, and energy calculations of the coexisting water molecules using the computer program WaterMap. Our results clearly showed that the heart-type FABP (FABP3) preferentially incorporates a U-shaped FA of C10-C18 using a lipid-compatible water cluster, and excludes longer FAs using a chain-length-limiting water cluster. These mechanisms could help us gain a general understanding of how proteins recognize diverse lipids with different chain lengths.

  10. 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.

  11. Physiological covalent regulation of rat liver branched-chain alpha-ketoacid dehydrogenase

    SciTech Connect

    Harris, R.A.; Powell, S.M.; Paxton, R.; Gillim, S.E.; Nagae, H.

    1985-12-01

    A radiochemical assay was developed for measuring branched-chain alpha-ketoacid dehydrogenase activity of Triton X-100 extracts of freeze-clamped rat liver. The proportion of active (dephosphorylated) enzyme was determined by measuring enzyme activities before and after activation of the complex with a broad-specificity phosphoprotein phosphatase. Hepatic branched-chain alpha-ketoacid dehydrogenase activity in normal male Wistar rats was 97% active but decreased to 33% active after 2 days on low-protein (8%) diet and to 13% active after 4 days on the same diet. Restricting protein intake of lean and obese female Zucker rats also caused inactivation of hepatic branched-chain alpha-ketoacid dehydrogenase complex. Essentially all of the enzyme was in the active state in rats maintained for 14 days on either 30 or 50% protein diets. This was also the case for rats maintained on a commercial chow diet (minimum 23% protein). However, maintaining rats on 20, 8, and 0% protein diets decreased the percentage of the active form of the enzyme to 58, 10, and 7% of the total, respectively. Fasting of chow-fed rats for 48 h had no effect on the activity state of hepatic branched-chain alpha-ketoacid dehydrogenase, i.e., 93% of the enzyme remained in the active state compared to 97% for chow-fed rats. However, hepatic enzyme of rats maintained on 8% protein diet was 10% active before starvation and 83% active after 2 days of starvation. Thus, dietary protein deficiency results in inactivation of hepatic branched-chain alpha-ketoacid dehydrogenase complex, presumably as a consequence of low hepatic levels of branched-chain alpha-ketoacids.

  12. 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.

  13. 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 %.

  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. 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.

  16. Superiority of branched side chains in spontaneous nanowire formation: exemplified by poly(3-2-methylbutylthiophene) for high-performance solar cells.

    PubMed

    Chen, Hsieh-Chih; Wu, I-Che; Hung, Jui-Hsiang; Chen, Fu-Je; Chen, I-Wen P; Peng, Yung-Kang; Lin, Chao-Sung; Chen, Chun-Hsien; Sheng, Yu-Jane; Tsao, Heng-Kwong; Chou, Pi-Tai

    2011-04-18

    One-dimensional nanostructures containing heterojunctions by conjugated polymers, such as nanowires, are expected to greatly facilitate efficient charge transfer in bulk-heterojunction (BHJ) solar cells. Thus, a combined theoretical and experimental approach is pursued to explore spontaneous nanowire formation. A dissipative particle dynamics simulation is first performed to study the morphologies formed by rodlike polymers with various side-chain structures. The results surprisingly predict that conjugated polymers with branched side chains are well suited to form thermodynamically stable nanowires. Proof of this concept is provided via the design and synthesis of a branched polymer of regioregular poly(3-2-methylbutylthiophene) (P3MBT), which successfully demonstrates highly dense nanowire formation free from any stringent conditions and stratagies. In BHJ solar cells fabricated using a blend of P3MBT and [6,6]-phenyl-C71-butyric acid methyl ester (PC(71) BM), P3MBT polymers are self-organized into highly crystalline nanowires with a d(100) spacing of 13.30 Å. The hole mobility of the P3MBT:PC(71) BM (1:0.5 by weight) blend film reaches 3.83 × 10(-4) cm(2) V(-1) s(-1) , and the maximum incident photon-to-current efficiency reaches 68%. The results unambiguously prove the spontaneous formation of nanowires using solution-processable conjugated polymers with branched alkyl side chains in BHJ solar cells.

  17. Aerobic biotransformation of alkyl branched aromatic alkanoic naphthenic acids via two different pathways by a new isolate of Mycobacterium.

    PubMed

    Johnson, Richard J; West, Charles E; Swaih, Aisha M; Folwell, Ben D; Smith, Ben E; Rowland, Steven J; Whitby, Corinne

    2012-04-01

    Naphthenic acids (NAs) are complex mixtures of carboxylic acids found in weathered crude oils and oil sands, and are toxic, corrosive and persistent. However, little is known about the microorganisms and mechanisms involved in NA degradation. We isolated a sediment bacterium (designated strain IS2.3), with 100% 16S rRNA gene sequence identity to Mycobacterium aurum, which degraded synthetic NAs (4'-n-butylphenyl)-4-butanoic acid (n-BPBA) and (4'-t-butylphenyl)-4-butanoic acid (t-BPBA). n-BPBA was readily oxidized with almost complete degradation (96.8% ± 0.3) compared with t-BPBA (77.8% ± 3.7 degraded) by day 49. Cell counts increased fourfold by day 14 but decreased after day 14 for both n- and t-BPBA. At day 14, (4'-butylphenyl)ethanoic acid (BPEA) metabolites were detected. Additional metabolites produced during t-BPBA degradation were identified by mass spectrometry of derivatives as (4'-carboxy-t-butylphenyl)-4-butanoic acid and (4'-carboxy-t-butylphenyl)ethanoic acid; suggesting that strain IS2.3 used omega oxidation of t-BPEA to oxidize the tert-butyl side-chain to produce (4'-carboxy-t-butylphenyl)ethanoic acid, as the primary route for biodegradation. However, strain IS2.3 also produced this metabolite through initial omega oxidation of the tert-butyl side-chain of t-BPBA, followed by beta-oxidation of the alkanoic acid side-chain. In conclusion, an isolate belonging to the genus Mycobacterium degraded highly branched aromatic NAs via two different pathways.

  18. Concentrations of volatile 4-alkyl-branched fatty acids in sheep and goat milk and dairy products.

    PubMed

    Kaffarnik, Stefanie; Kayademir, Yasemin; Heid, Carolina; Vetter, Walter

    2014-11-01

    Goat and sheep milk and dairy products thereof are characterized by a strong and unique flavor. In this context, the volatile minor fatty acid 4-ethyloctanoic acid plays a prominent role along with 4-methyloctanoic acid when both are present in free form. Using a novel GC/MS method in the selected ion-monitoring mode, previously developed for sheep subcutaneous adipose tissue, we were able to analyze the total concentrations of these flavor-relevant minor fatty acids as methyl esters in goat and sheep milk as well as in their products. Differences between the concentrations and ratios of 4-methyloctanoic acid and 4-ethyloctanoic acid in goat milk (n = 4), goat cheese (n = 4), sheep milk (n = 2), and sheep cheese (n = 4) were observed. Goat milk and cheese resulted in higher concentrations for both fatty acids (190 to 480 μg/g milk fat) and smaller 4-Me-8:0 to 4-Et-8:0 ratios (1.4 to 2.7) compared to sheep milk and cheese (78 to 220 μg/g milk fat; 4-Me-8:0 to 4-Et-8:0 ratio: 15 to 42). In all samples, the concentration of 4-Me-8:0 exceeded the one of 4-Et-8:0. However, due to its lower flavor threshold value the contribution of 4-Et-8:0 to the flavor was generally >76%. The calculated flavor values were >1400 for goat milk and cheeses and >200 for sheep milk and cheeses. In goat milk and its products, only a proportion of <0.1% 4-alkyl-branched fatty acids present in free form in the goat milk and <0.5% in the sheep samples would be sufficient to generate the characteristic goaty flavor. Parameters that promote or prevent the release of 4-Me-8:0, and especially 4-Et-8:0, will be decisive for the flavor in the resulting dairy product.

  19. Techno-economic analysis of an improved process for producing saturated branched-chain fatty acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetable oils provide a source of environmentally desirable lubricants, but they are not widely utilized because of their poor oxidative stability. Branched-chain fatty acid isomers are desirable products because they have excellent thermostabilities and lubricities when compared to the parent veg...

  20. 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...

  1. Improved synthesis and characterization of saturated branched-chain fatty acid isomers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The development of viable technologies for producing green products from renewable fats and oils is highly desirable since such materials can serve as replacements for non-renewable and poorly biodegradable petroleum-based products. Mixtures of saturated branched-chain fatty acid isomers (sbc-FAs),...

  2. 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

  3. 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...

  4. 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

    2016-07-04

    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.

  5. The transfection efficiency of calix[4]arene-based lipids: the role of the alkyl chain length.

    PubMed

    Mochizuki, Shinichi; Nishina, Koichi; Fujii, Shota; Sakurai, Kazuo

    2015-02-01

    The size, surface charge, and microstructure of lipoplexes comprising cationic lipids and nucleic acids are important factors for transfection efficiency. As these properties are largely determined by the cationic lipids used, a number of studies on the relationship between cationic lipids and the transfection efficiency have been reported. Among the many cationic lipids, lipids with multivalent cationic head groups are expected to be potent transfection reagents. Here, we prepared calix[4]arene-based lipids with different alkyl chain lengths from C3 to C15 and evaluated the relationship between the alkyl chain length and the transfection efficiency. C6 lipoplexes exhibited the highest transfection efficiency among all lipoplexes. The gene expression with C9 and C12 lipoplexes was slightly lower than that with C6 lipoplexes. C3 lipoplexes hardly induced gene expression, while C15 lipoplexes exhibited no complexation with plasmid DNA. Although all lipoplexes exhibited nearly identical characteristics, they exhibited different behaviours in terms of the interactions between the lipoplexes and anionic micelles comprising phosphatidylserine, a model of endosomal vehicle. After mixing with phosphatidylserine micelles, C6 lipoplexes released the bound plasmid DNA at pH 5 but not at pH 7, indicating that they can interact with the late endosomal membrane after being incorporated into cells. No plasmid DNA was released from C9 or C12 lipoplexes at either pH values. Thus, the alkyl chain length of cationic lipids is related to their interaction with the endosomal compartment and can provide a basis for the design of novel transfection reagents.

  6. Molecular structure of an alkyl-side-chain polymer-water interface: origins of contact angle hysteresis.

    PubMed

    Rangwalla, Hasnain; Schwab, Alexander D; Yurdumakan, Betül; Yablon, Dalia G; Yeganeh, Mohsen S; Dhinojwala, Ali

    2004-09-28

    A new and direct approach to verify surface heterogeneity as the microscopic origin of contact-angle hysteresis is demonstrated. IR-visible sum-frequency-generation spectroscopy (SFG) was used to selectively probe the molecules at the interface of an alkyl-side-chain polymer [poly(vinyl n-octadecyl carbamate-co-vinyl acetate)] with water. The spectra indicate that in contact with water, the polymer surface is heterogeneous (having areas of differing surface energies). This evidence of surface heterogeneity supports the hysteresis observed in the advancing and receding contact angles of the polymer surface with water. The same measurements made for the chemically and structurally similar surface of an octadecyltrichlorosilane self-assembled monolayer indicates a homogeneous surface at the water interface. In this case, contact-angle hysteresis measurements implicate surface roughness as the cause of hysteresis. Atomic force microscopy measurements of roughness for these surfaces further support our conclusions. The polymer-water interface was probed using SFG at above-ambient temperatures, and an order-to-disorder transition (ODT) of alkyl side chains at the interface was observed, which closely follows the melting of crystalline side chains in the bulk. This transition explains the increased wettability of the polymer, by water, when the temperature is raised above the bulk melting temperature. Furthermore, the irreversibility of this ODT suggests that the disordered polymer-water interface is the thermodynamic equilibrium state, whereas the before-heating structure of this interface is a kinetically hindered metastable state.

  7. 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.

  8. Microemulsion breakdown by pervaporation technique: effect of the alkyl chain length of n-alkanol, a cosurfactant of the microemulsion.

    PubMed

    Moulay, Saâd; Hadj-Ziane, Amel Zafour; Canselier, Jean-Paul

    2007-07-15

    Two sets of microemulsions, cyclohexane- and water-rich ones, were prepared with the following n-alkanols as cosurfactants: n-propanol, n-butanol, n-pentanol, and n-hexanol. The results showed the influence of the alkyl chain length of the n-alkanol on the permselectivity properties of the pervaporation technique in the breakdown of the microemulsions. The variations of the total flux rate J and the enrichment factor beta were in parallel with the effect of the cosurfactant on the swelling extent of the PDMS membrane.

  9. Ufd2p synthesizes branched ubiquitin chains to promote the degradation of substrates modified with atypical chains

    PubMed Central

    Liu, Chao; Liu, Weixiao; Ye, Yihong; Li, Wei

    2017-01-01

    Ubiquitination of a subset of proteins by ubiquitin chain elongation factors (E4), represented by Ufd2p in Saccharomyces cerevisiae, is a pivotal regulator for many biological processes. However, the mechanism of Ufd2p-mediated ubiquitination is largely unclear. Here, we show that Ufd2p catalyses K48-linked multi-monoubiquitination on K29-linked ubiquitin chains assembled by the ubiquitin ligase (Ufd4p), resulting in branched ubiquitin chains. This reaction depends on the interaction of K29-linked ubiquitin chains with two N-terminal loops of Ufd2p. Only following the addition of K48-linked ubiquitin to substrates modified with K29-linked ubiquitin chains, can the substrates be escorted to the proteasome for degradation. We demonstrate that this ubiquitin chain linkage switching reaction is essential for ERAD, oleic acid and acid pH resistance in yeast. Thus, our results suggest that Ufd2p functions by switching ubiquitin chain linkages to allow the degradation of proteins modified with a ubiquitin linkage, which is normally not targeted to the proteasome. PMID:28165462

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

    PubMed Central

    Mecinović, Jasmin; Snyder, Phillip W.; Mirica, Katherine A.; Bai, Serena; Mack, Eric T.; Kwant, Richard L.; Moustakas, Demetri T.; Heroux, Annie; Whitesides, George M.

    2011-01-01

    The hydrophobic effect—the free-energetically favorable association of non-polar 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 (H2NSO2C6H4-CONHCH2(CX2)nCX3, 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 non-optimally 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 entropic contributions to the hydrophobic

  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. The role of alkyl chain length of monothiol-terminated alkyl carboxylic acid in the synthesis, characterization, and application of gelatin-g-poly(N-isopropylacrylamide) carriers for antiglaucoma drug delivery.

    PubMed

    Luo, Li-Jyuan; Lai, Jui-Yang

    2017-02-01

    To improve ocular bioavailability and extend pharmacological response, this study aims to investigate the role of alkyl chain length of monothiol-terminated alkyl carboxylic acids in the synthesis, characterization, and application of gelatin-g-poly(N-isopropylacrylamide) (GN) biodegradable in situ gelling carriers for antiglaucoma drug delivery. In the presence of mercaptoacetic acid (MAA), mercaptopropionic acid (MPA), mercaptobutyric acid (MBA), or mercaptohexanoic acid (MHA) as a chain transfer agent, the carboxylic end-capped poly(N-isopropylacrylamide) samples were prepared by free radical polymerization technique. Our results showed that with increasing alkyl chain length, the hydrophobicity of thermo-responsive polymer segments significantly increased, mainly due to an increase in CH stretching frequencies. In addition, the greater hydrophobic association favored the decrease in both phase transition temperature and weight loss of GN copolymers, thereby accelerating their temperature-triggered gelation process and retarding the degradation progress under physiological conditions. The benefits from these features allowed the pilocarpine carriers to increase drug payload and extend drug release. Irrespective of carbon number of monothiol-terminated alkyl carboxylic acid, the synthesized GN materials exhibited high tolerance to corneal endothelial cells without any evidence of inhibited proliferation, viability loss, inflammatory stimulation, and functional abnormality, indicating good biocompatibility. Results of clinical observations and histological examinations demonstrated that the therapeutic efficacies in treating glaucomatous damage are in response to in vivo drug release profiles from various intracamerally injected GN carriers. The research findings suggest the influence of alkyl chain length of chain transfer agent-mediated polymer hydrophobicity and degradability on pharmacological bioavailability and action of pilocarpine in a glaucomatous rabbit

  13. 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

  14. 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.

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

    PubMed

    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.

  16. Equine endurance exercise alters serum branched-chain amino acid and alanine concentrations.

    PubMed

    Trottier, N L; Nielsen, B D; Lang, K J; Ku, P K; Schott, H C

    2002-09-01

    Six 2-year-old Arabian horses were used to determine whether 60 km prolonged endurance exercise (approximately 4 h) alters amino acid concentrations in serum and muscle, and the time required for serum amino acid concentrations to return to basal resting values. Blood and muscle samples were collected throughout exercise and during a 3 day recovery period. Isoleucine concentration in muscle tended to increase and leucine and valine did not change due to exercise. Serum alanine concentrations did not increase immediately after exercise, but increased at 24, 48 and 72 h postexercise. Serum isoleucine, leucine, and valine concentrations decreased after exercise and time required to reach pre-exercising concentrations was 48 h. In conclusion, endurance exercise in the horse decreases serum isoleucine, leucine, and valine concentrations, and increases serum alanine concentration. The decrease in serum branched-chain amino acid concentrations did not correspond to a measurable increase in total muscle branched-chain amino acid concentrations.

  17. Biodegradation of the endocrine disrupter 4-tert-octylphenol by the yeast strain Candida rugopelliculosa RRKY5 via phenolic ring hydroxylation and alkyl chain oxidation pathways.

    PubMed

    Rajendran, Ranjith Kumar; Huang, Shir-Ly; Lin, Chu-Ching; Kirschner, Roland

    2017-02-01

    4-(1,1,3,3-tetramethylbutane)-phenol (4-tert-OP) is one of the most prevalent endocrine disrupting pollutants. Information about bioremediation of 4-tert-OP remains limited, and no study has been reported on the mechanism of 4-tert-OP degradation by yeasts. The yeast Candida rugopelliculosa RRKY5 was proved to be able to utilize 4-methylphenol, bisphenol A, 4-ethylphenol, 4-tert-butylphenol, 4-tert-OP, 4-tert-nonylphenol, isooctane, and phenol under aerobic conditions. The optimum conditions for 4-tert-OP degradation were 30°C, pH 5.0, and an initial 4-tert-OP concentration of 30mgL(-1); the maximum biodegradation rate constant was 0.107d(-1), equivalent to a minimum half-life of 9.6d. Scanning electron microscopy revealed formation of arthroconidia when cells were grown in the presence of 4-tert-OP, whereas the cells remained in the budding form without 4-tert-OP. Identification of the 4-tert-OP degradation metabolites using liquid chromatography-hybrid mass spectrometry revealed three different mechanisms via both branched alkyl side chain and aromatic ring cleavage pathways.

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

    PubMed

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

    2015-12-01

    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.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. Branched-chain amino acids vs lactulose in the treatment of hepatic coma: a controlled study.

    PubMed

    Rossi-Fanelli, F; Riggio, O; Cangiano, C; Cascino, A; De Conciliis, D; Merli, M; Stortoni, M; Giunchi, G

    1982-10-01

    A controlled study was carried out in two groups of 20 patients with cirrhosis of the liver and deep coma in order to compare the efficacy of intravenous branched-chain amino acid solutions in 20% glucose (group A) vs lactulose plus glucose in isocaloric amount (group B). There were 3 drop-outs from each group. Plasma amino acids and ammonia were assayed at fixed intervals throughout the 10-day observation period. Routine tests were assayed daily. Complete mental recovery was obtained in 70% of patients in group A and in 47% in group B. The difference was not significant, likely due to the lack of placebo group. With the exception of free tryptophan/all competing amino acids ratio, the modifications in plasma amino acid levels showed no correlation with the clinical course under either treatment. Ammonia, like free tryptophan, decreased significantly upon mental recovery, paralleling the clinical course throughout the study. In conclusion, branched-chain amino acids are at least as effective as lactulose in deep hepatic coma. It is suggested that branched-chain amino acids may reverse coma either by competing with brain entry of the aromatic amino acid or by metabolically decreasing free tryptophan and ammonia.

  4. Branched-chain amino acid metabolism: from rare Mendelian diseases to more common disorders

    PubMed Central

    Burrage, Lindsay C.; Nagamani, Sandesh C.S.; Campeau, Philippe M.; Lee, Brendan H.

    2014-01-01

    Branched-chain amino acid (BCAA) metabolism plays a central role in the pathophysiology of both rare inborn errors of metabolism and the more common multifactorial diseases. Although deficiency of the branched-chain ketoacid dehydrogenase (BCKDC) and associated elevations in the BCAAs and their ketoacids have been recognized as the cause of maple syrup urine disease (MSUD) for decades, treatment options for this disorder have been limited to dietary interventions. In recent years, the discovery of improved leucine tolerance after liver transplantation has resulted in a new therapeutic strategy for this disorder. Likewise, targeting the regulation of the BCKDC activity may be an alternative potential treatment strategy for MSUD. The regulation of the BCKDC by the branched-chain ketoacid dehydrogenase kinase has also been implicated in a new inborn error of metabolism characterized by autism, intellectual disability and seizures. Finally, there is a growing body of literature implicating BCAA metabolism in more common disorders such as the metabolic syndrome, cancer and hepatic disease. This review surveys the knowledge acquired on the topic over the past 50 years and focuses on recent developments in the field of BCAA metabolism. PMID:24651065

  5. Relationships between pyruvate decarboxylation and branched-chain volatile acid synthesis in Ascaris mitochondria.

    PubMed

    Komuniecki, R; Komuniecki, P R; Saz, H J

    1981-10-01

    The rate of 14CO2 evolution from 1-[14C]pyruvate by intact Ascaris mitochondria was very slow, but increased with increasing concentrations of pyruvate. At all concentrations of pyruvate, in an aerobic environment, pyruvate decarboxylation was stimulated greatly by the addition of fumarate, malate, or succinate. However, under anaerobic conditions, only malate and fumarate stimulated pyruvate decarboxylation; succinate had no effect. This implies that the aerobic metabolism of succinate, presumably to other dicarboxylic acids, may be required for the stimulation. Incubation of sonicated mitochondria with pyruvate plus fumarate, under rate-limiting concentrations of NAD+, resulted in approximately equal quantities of pyruvate utilized and succinate formed, suggesting that pyruvate oxidation and fumarate reduction may be linked. Branched-chain, volatile fatty acids were not formed during incubations with either malate or succinate, or succinate plus acetate. However, incubations of intact Ascaris mitochondria with pyruvate plus succinate yielded 2-methylbutyrate and 2-methylvalerate, whereas incubations with pyruvate plus propionate yielded almost exclusively 2-methylvalerate. Oxygen dramatically inhibited the synthesis of the branched-chain acids from succinate plus pyruvate, attesting to the apparent anaerobic nature of Ascaris mitochondrial metabolism. Significantly, the addition of glucose plus ADP stimulated the formation of all volatile fatty acids. Therefore, the synthesis of branched-chain acids may be related directly to increased energy generation. Alternatively, they may function in the regulatory role of maintaining the mitochondrial redox balance.

  6. 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.

  7. 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.

  8. Effect of fluorination and size of the alkyl side-chain on the solubility of carbon dioxide in 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ionic liquids.

    PubMed

    Almantariotis, D; Gefflaut, T; Pádua, A A H; Coxam, J-Y; Costa Gomes, M F

    2010-03-18

    It is proven in this work that it is possible to significantly increase the carbon dioxide uptake by an ionic liquid relying on physical interactions only. The solubility and thermodynamics of solvation of carbon dioxide in the ionic liquids 1-octyl-3-methylimidazolium bis[trifluoromethylsulfonyl]amide [C(8)mim][Ntf(2)], 1-decyl-3-methylimidazolium bis[trifluoromethylsulfonyl]amide [C(10)mim][Ntf(2)], and 1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-3-methylimidazolium bis[trifluoromethylsulfonyl]amide [C(8)H(4)F(13)mim][Ntf(2)] were determined experimentally between 298 and 343 K at pressures close to atmospheric. The solubility of carbon dioxide is significantly higher in the fluorine-substituted ionic liquid with Henry's law constants at 303 K of 33.3 and 30.7 bar for [C(8)mim][Ntf(2)] and [C(10)mim][Ntf(2)], respectively, and of 28.0 bar for [C(8)H(4)F(13)mim][Ntf(2)]. Molecular simulation was used for interpreting the molecular mechanisms of solvation of carbon dioxide in the studied ionic liquids and coherent molecular mechanisms of solvation are proposed in light of the solute-solvent radial distribution functions. It is shown that the increase of the size of the hydrogenated or fluorinated alkyl chain in the imidazolium cation does not lead to a steady augmentation of the gaseous uptake by the liquid probably due to an increase of the nonpolar domains of the ionic liquid, carbon dioxide being solvated preferentially in the charged regions of the solvent.

  9. Sequence-specific DNA alkylation and transcriptional inhibition by long-chain hairpin pyrrole-imidazole polyamide-chlorambucil conjugates targeting CAG/CTG trinucleotide repeats.

    PubMed

    Asamitsu, Sefan; Kawamoto, Yusuke; Hashiya, Fumitaka; Hashiya, Kaori; Yamamoto, Makoto; Kizaki, Seiichiro; Bando, Toshikazu; Sugiyama, Hiroshi

    2014-09-01

    Introducing novel building blocks to solid-phase peptide synthesis, we readily synthesized long-chain hairpin pyrrole-imidazole (PI) polyamide-chlorambucil conjugates 3 and 4 via the introduction of an amino group into a GABA (γ-turn) contained in 3, to target CAG/CTG repeat sequences, which are associated with various hereditary disorders. A high-resolution denaturing polyacrylamide sequencing gel revealed sequence-specific alkylation both strands at the N3 of adenines or guanines in CAG/CTG repeats by conjugates 3 and 4, with 11bp recognition. In vitro transcription assays using conjugate 4 revealed that specific alkylation inhibited the progression of RNA polymerase at the alkylating sites. Chiral substitution of the γ-turn with an amino group resulted in higher binding affinity observed in SPR assays. These assays suggest that conjugates 4 with 11bp recognition has the potential to cause specific DNA damage and transcriptional inhibition at the alkylating sites.

  10. 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.

  11. Triggering hairpin-free chain-branching growth of fluorescent DNA dendrimers for nonlinear hybridization chain reaction.

    PubMed

    Xuan, Feng; Hsing, I-Ming

    2014-07-16

    We present a nonlinear hybridization chain reaction (HCR) system in which a trigger DNA initiates self-sustained assembly of quenched double-stranded substrates into fluorescent dendritic nanostructures. During the process, an increasing number of originally sequestered trigger sequences labeled with fluorescent reporters are freed up from quenched substrates, leading to chain-branching growth of the assembled DNA dendrimers and an exponential increase in the fluorescence intensity. The triggered assembly behavior was examined by PAGE analysis, and the morphologies of the grown dendrimers were verified by AFM imaging. The exponential kinetics of the fluorescence accumulation was also confirmed by time-dependent fluorescence spectroscopy. This method adopts a simple sequence design strategy, the concept of which could be adapted to program assembly systems with higher-order growth kinetics.

  12. 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.

  13. 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.

  14. Calorimetric and spectroscopic evidence of chain-melting in smectic E and smectic A phases of 4-alkyl-4'-isothiocyanatobiphenyl (nTCB).

    PubMed

    Yamamura, Yasuhisa; Adachi, Takuya; Miyazawa, Takahito; Horiuchi, Katsuya; Sumita, Masato; Massalska-Arodź, Maria; Urban, Stanisław; Saito, Kazuya

    2012-08-02

    To confirm the molten state of the alkyl chain in soft crystalline phase, smectic E (SmE) phase, thermodynamic and spectroscopic analyses were performed on 4-n-alkyl-4'-isothiocyanatobiphenyl (nTCB, n: the number of carbon atoms in the alkyl group). DSC results of 11TCB and 12TCB, having extra smectic A phase besides smectic E phase, show that their chain-length dependence of entropies of transition (Δ(trs)S) from the ordered crystalline (OC) phase to the SmE phase matches the trend found for nTCB (n = 4-10), while no chain-length dependence is observed in Δ(trs)S at the SmE-to-SmA and SmA-to-isotropic liquid (IL) phase transitions in 11TCB and 12TCB. Temperature dependences of FT-IR spectra of six compounds (n = 2, 3, 5, 8, 10, and 12) were recorded. The CH stretching modes of the chain exhibited more pronounced change at the transition from the OC to the SmE phase than at the transition from the SmE phase to the IL or SmA phase. These results indicate that the alkyl chain is molten in the SmE phase as in IL. The disordering process of nTCB molecules from the OC to IL via anisotropic mesophases is discussed in terms of entropy.

  15. Ultrafast energy transfer from rigid, branched side-chains into a conjugated, alternating copolymer

    PubMed Central

    Griffin, Graham B.; Lundin, Pamela M.; Rolczynski, Brian S.; Linkin, Alexander; McGillicuddy, Ryan D.; Bao, Zhenan; Engel, Gregory S.

    2014-01-01

    We present the synthesis and characterization of a benzodithiophene/thiophene alternating copolymer decorated with rigid, singly branched pendant side chains. We characterize exciton migration and recombination dynamics in these molecules in tetrahydrofuran solution, using a combination of static and time-resolved spectroscopies. As control experiments, we also measure electronic relaxation dynamics in isolated molecular analogues of both the side chain and polymer moieties. We employ semi-empirical and time-dependent density functional theory calculations to show that photoexcitation of the decorated copolymer using 395 nm laser pulses results in excited states primarily localized on the pendant side chains. We use ultrafast transient absorption spectroscopy to show that excitations are transferred to the polymer backbone faster than the instrumental response function, ∼250 fs. PMID:25669410

  16. Ultrafast energy transfer from rigid, branched side-chains into a conjugated, alternating copolymer

    SciTech Connect

    Griffin, Graham B.; Rolczynski, Brian S.; Linkin, Alexander; McGillicuddy, Ryan D.; Engel, Gregory S.; Lundin, Pamela M.; Bao, Zhenan

    2014-01-21

    We present the synthesis and characterization of a benzodithiophene/thiophene alternating copolymer decorated with rigid, singly branched pendant side chains. We characterize exciton migration and recombination dynamics in these molecules in tetrahydrofuran solution, using a combination of static and time-resolved spectroscopies. As control experiments, we also measure electronic relaxation dynamics in isolated molecular analogues of both the side chain and polymer moieties. We employ semi-empirical and time-dependent density functional theory calculations to show that photoexcitation of the decorated copolymer using 395 nm laser pulses results in excited states primarily localized on the pendant side chains. We use ultrafast transient absorption spectroscopy to show that excitations are transferred to the polymer backbone faster than the instrumental response function, ∼250 fs.

  17. Ultrafast energy transfer from rigid, branched side-chains into a conjugated, alternating copolymer.

    PubMed

    Griffin, Graham B; Lundin, Pamela M; Rolczynski, Brian S; Linkin, Alexander; McGillicuddy, Ryan D; Bao, Zhenan; Engel, Gregory S

    2014-01-21

    We present the synthesis and characterization of a benzodithiophene/thiophene alternating copolymer decorated with rigid, singly branched pendant side chains. We characterize exciton migration and recombination dynamics in these molecules in tetrahydrofuran solution, using a combination of static and time-resolved spectroscopies. As control experiments, we also measure electronic relaxation dynamics in isolated molecular analogues of both the side chain and polymer moieties. We employ semi-empirical and time-dependent density functional theory calculations to show that photoexcitation of the decorated copolymer using 395 nm laser pulses results in excited states primarily localized on the pendant side chains. We use ultrafast transient absorption spectroscopy to show that excitations are transferred to the polymer backbone faster than the instrumental response function, ∼250 fs.

  18. Graphene oxide derivatives with variable alkyl chain length and terminal functional groups as supports for stabilization of cytochrome c.

    PubMed

    Patila, Michaela; Pavlidis, Ioannis V; Kouloumpis, Antonios; Dimos, Konstantinos; Spyrou, Konstantinos; Katapodis, Petros; Gournis, Dimitrios; Stamatis, Haralambos

    2016-03-01

    In this study we report the ability of reduced and non-reduced graphene oxide-based nanomaterials (GONs), modified with variable alkyl chain length and terminal functional groups, to act as effective scaffolds for the immobilization of cytochrome c (cyt c) using different immobilization procedures. The GONs/cyt c conjugates are characterized by a combination of techniques, namely atomic force microscopy, X-ray photoelectron and FT-IR spectroscopies as well as thermo-gravimetric and differential thermal analysis. The effect of the structure of functional groups and the surface chemistry of GONs on the immobilization efficiency, the peroxidase activity and the stability of the cyt c was investigated and correlated with conformational changes on the protein molecule upon immobilization. The enhanced thermal stability (up to 2-fold) and increased tolerance (up to 25-fold) against denaturing agents observed for immobilized cyt c, indicates that these functionalized GONs are suitable as nanoscaffolds for the development of robust nanobiocatalysts.

  19. Designing green plasticizers: influence of alkyl chain length on biodegradation and plasticization properties of succinate based plasticizers.

    PubMed

    Erythropel, Hanno C; Dodd, Patrick; Leask, Richard L; Maric, Milan; Cooper, David G

    2013-04-01

    Phthalate diesters such as di (2-ethylhexyl) phthalate (DEHP) are considered ubiquitous contaminants and are poorly biodegraded in the environment. Moreover, both the parent compound and stable metabolites such as mono (2-ethylhexyl) phthalate (MEHP) are linked to several negative impacts on the environment and human health. Earlier work established that saturated diester compounds, such as succinates, showed better biodegradation characteristics and comparable plasticizer properties compared to DEHP. In this work we examine the effect of alkyl chain length of succinate molecules on plasticizer and biodegradation properties. This included both the side chains (n-ethyl to n-octyl) as well as substituents on the middle part of the succinate molecule. We showed that the common soil bacterium Rhodococcus rhodocrous could rapidly break down all unsubstituted succinates, without the appearance of stable metabolites. Furthermore, the organisms used the plasticizer metabolites as carbon source. The introduction of a large cyclohexyl substituent on the succinate resulted in a poorer degradation rate. Glass Transition Temperature (Tg) measurements were performed to evaluate plasticizer properties and showed that longer side chains reduced the Tg more efficiently, while large cyclohexyl substituents on the succinate decreased this effect. However, all compounds performed better or equal to DEHP at reducing the Tg.

  20. 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

    2016-07-07

    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.

  1. Rotational dynamics of coumarin-153 and 4-aminophthalimide in 1-ethyl-3-methylimidazolium alkylsulfate ionic liquids: effect of alkyl chain length on the rotational dynamics.

    PubMed

    Das, Sudhir Kumar; Sarkar, Moloy

    2012-01-12

    Rotational dynamics of two neutral organic solutes, coumarin-153 (C-153) and 4-aminophthalimide (AP), with only the latter having hydrogen-bond-donating ability, has been investigated in a series of 1-ethyl-3-methylimidazolium alkyl sulfate ionic liquids as a function of temperature. The ionic liquids differ only in the length of the linear alkyl side chain (alkyl = ethyl, butyl, hexyl, and octyl) on the anionic moiety. The present study has been undertaken to examine the role of alkyl side chains on the rotational dynamics of the two solutes in these ionic liquids. Analysis of the results using Stokes-Einstein-Debye hydrodynamic theory indicates that the rotational dynamics of C-153 lies between the stick and slip boundary condition in the ethyl analogue and finally reaches subslip condition as in case of the octyl substituent. The observed rotational behavior of C-153 has been explained on the basis of an increase in the size of the solvent, which offers lower friction for solute rotation. On the other hand, AP shows superstick behavior in the ethyl system and exceeds the stick limit in the octyl derivative. Superstick behavior of AP has been attributed to the specific hydrogen-bonding interaction between AP and the sulfate moiety. Proton NMR investigation confirms the hydrogen-bonding interaction between the N-H hydrogen of AP and the ionic liquid. The decrease in rotational coupling constant values for AP with increasing length of alkyl side chains has been attributed to the decrease in the solute-solvent-specific interaction with an increase in the alkyl side chain length on the sulfate moiety.

  2. 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

    2015-04-07

    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.

  3. 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.

  4. Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

    NASA Astrophysics Data System (ADS)

    Huo, Lixia; Du, Pengcheng; Zhou, Hui; Zhang, Kaifeng; Liu, Peng

    2017-02-01

    It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C6, C12, or C18) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8° of the hydroxylated silicon substrate to near 60° after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (Ra) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al2O3 ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C12 alkyl chain (C12-SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C12-SAM with desirable alkyl chain length.

  5. 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.

  6. Oligo(ethylene glycol)-incorporated hybrid linear alkyl side chains for n-channel polymer semiconductors and their effect on the thin-film crystalline structure.

    PubMed

    Kim, Ran; Kang, Boseok; Sin, Dong Hun; Choi, Hyun Ho; Kwon, Soon-Ki; Kim, Yun-Hi; Cho, Kilwon

    2015-01-28

    Oligo(ethylene glycol)-incorporated hybrid linear alkyl side chains, serving as solubilizing groups, are designed and introduced into naphthalene-diimide-based n-channel copolymers. The synthesized polymers exhibit unipolar n-type operation with an electron mobility of up to 1.64 cm(2) V(-1) s(-1), which demonstrates the usefulness of the hybrid side chains in polymer electronics applications.

  7. 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.

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

    PubMed Central

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

    2016-01-01

    Cholest-4-en-3-one, whether added exogenously or generated intracellularly from cholesterol, inhibits the growth of Mycobacterium tuberculosis when 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 of M. 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 of M. tuberculosis. PMID:26833565

  9. INTERACTIONS IN THE METABOLISM OF GLUTAMATE AND THE BRANCHED-CHAIN AMINO ACIDS AND KETOACIDS IN THE CNS

    PubMed Central

    Yudkoff, Marc

    2016-01-01

    Glutamatergic neurotransmission entails a tonic loss of glutamate from nerve endings into the synapse. Replacement of neuronal glutamate is essential in order to avoid depletion of the internal pool. In brain this occurs primarily via the glutamate-glutamine cycle, which invokes astrocytic synthesis of glutamine and hydrolysis of this amino acid via neuronal phosphate-dependent glutaminase. This cycle maintains constancy of internal pools, but it does not provide a mechanism for inevitable losses of glutamate N from brain. Importation of glutamine or glutamate from blood does not occur to any appreciable extent. However, the branched-chain amino acids (BCAA) cross the blood-brain barrier swiftly. The brain possesses abundant branched-chain amino acid transaminase activity which replenishes brain glutamate and also generates branched-chain ketoacids. It seems probable that the branched-chain amino acids and ketoacids participate in a “glutamate-BCAA cycle” which involves shuttling of branched-chain amino acids and ketoacids between astrocytes and neurons. This mechanism not only supports the synthesis of glutamate, it also may constitute a mechanism by which high (and potentially toxic) concentrations of glutamate can be avoided by the re-amination of branched-chain ketoacids. PMID:27696119

  10. Interactions in the Metabolism of Glutamate and the Branched-Chain Amino Acids and Ketoacids in the CNS.

    PubMed

    Yudkoff, Marc

    2017-01-01

    Glutamatergic neurotransmission entails a tonic loss of glutamate from nerve endings into the synapse. Replacement of neuronal glutamate is essential in order to avoid depletion of the internal pool. In brain this occurs primarily via the glutamate-glutamine cycle, which invokes astrocytic synthesis of glutamine and hydrolysis of this amino acid via neuronal phosphate-dependent glutaminase. This cycle maintains constancy of internal pools, but it does not provide a mechanism for inevitable losses of glutamate N from brain. Import of glutamine or glutamate from blood does not occur to any appreciable extent. However, the branched-chain amino acids (BCAA) cross the blood-brain barrier swiftly. The brain possesses abundant branched-chain amino acid transaminase activity which replenishes brain glutamate and also generates branched-chain ketoacids. It seems probable that the branched-chain amino acids and ketoacids participate in a "glutamate-BCAA cycle" which involves shuttling of branched-chain amino acids and ketoacids between astrocytes and neurons. This mechanism not only supports the synthesis of glutamate, it also may constitute a mechanism by which high (and potentially toxic) concentrations of glutamate can be avoided by the re-amination of branched-chain ketoacids.

  11. PGC-1α-mediated branched-chain amino acid metabolism in the skeletal muscle.

    PubMed

    Hatazawa, Yukino; Tadaishi, Miki; 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.

  12. Applying Alkyl-Chain Surface Functionalizations in Mesoporous Inorganic Structures: Their Impact on Gas Flow and Selectivity Depending on Temperature.

    PubMed

    Besser, Benjamin; Ahmed, Atiq; Baune, Michael; Kroll, Stephen; Thöming, Jorg; Rezwan, Kurosch

    2016-10-12

    Porous inorganic capillary membranes are prepared to serve as model structures for the experimental investigation of the gas transport in functionalized mesopores. The porous structures possess a mean pore diameter of 23 nm which is slightly reduced to 20 nm after immobilizing C16-alkyl chains on the surface. Gas permeation measurements are performed at temperatures ranging from 0 to 80 °C using Ar, N2, and CO2. Nonfunctionalized structures feature a gas transport according to Knudsen diffusion with regard to gas flow and selectivity. After C16-functionalization, the gas flow is reduced by a factor of 10, and the ideal selectivities deviate from the Knudsen theory. CO2 adsorption measurements show a decrease in total amount of adsorbed gas and isosteric heat of adsorption. It is hypothesized that the immobilized C16-chains sterically influence the gas transport behavior without a contribution from adsorption effects. The reduced gas flow derives from an additional surface resistance caused by the C16-chains spacially limiting the adsorption and desorption directions for gas molecules propagating through the structure, resulting in longer diffusion paths. In agreement, the gas flow is found to correlate with the molecular diameter of the gas species (CO2 < Ar < N2) increasing the resistance for larger molecules. This affects the ideal selectivities with the relation [Formula: see text]. The influence on selectivity increases with increasing temperature which leads to the conclusion that the temperature induced movement of the C16-chains is responsible for the stronger interaction between gas molecules and surface functional groups.

  13. 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.

  14. Effect of alkyl chain length and hydroxyl group functionalization on the surface properties of imidazolium ionic liquids.

    PubMed

    Pensado, Alfonso S; Costa Gomes, Margarida F; Canongia Lopes, José N; Malfreyt, Patrice; Pádua, Agílio A H

    2011-08-14

    Properties of the surface of ionic liquids, such as surface tension, ordering, and charge and density profiles, were studied using molecular simulation. Two types of modification in the molecular structure of imidazolium cations were studied: the length of the alkyl side chain and the presence of a polar hydroxyl group at the end of the side chain. Four ionic liquids were considered: 1-ethyl-3-methylimidazolium tetrafluoroborate, [C(2)C(1)im][BF(4)]; 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate, [C(2)OHC(1)im][BF(4)]; 1-octyl-3-methylimidazolium tetrafluoroborate, [C(8)C(1)im][BF(4)] and 1-(8-hydroxyoctyl)-3-methylimidazolium tetrafluoroborate, [C(8)OHC(1)im][BF(4)]. The surface tension was calculated using both mechanical and thermodynamic definitions, with consistent treatment of the long-range corrections. The simulations reproduce the available experimental values of surface tension with a maximum deviation of ±10%. This energetic characterization of the interface is completed by microscopic structural analysis of orientational ordering at the interface and density profiles along the direction normal to the interface. The presence of the hydroxyl group modifies the local structure at the interface, leading to a less organized liquid phase. The results allow us to relate the surface tension to the structural ordering at the liquid-vacuum interface.

  15. 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.

  16. 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.

  17. 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

  18. Nutritional status affects branched-chain oxoacid dehydrogenase activity during exercise in humans.

    PubMed

    Jackman, M L; Gibala, M J; Hultman, E; Graham, T E

    1997-02-01

    We examined the effect of glycogen availability and branched-chain amino acid (BCAA) supplementation on branched-chain oxoacid dehydrogenase (BCOAD) activity during exercise. Six subjects cycled at approximately 75% of their maximal oxygen uptake to exhaustion on three occasions under different preexercise conditions: 1) low muscle glycogen (LOW), 2) low muscle glycogen plus BCAA supplementation (LOW+BCAA), and 3) high muscle glycogen (CON). The LOW trial was performed first, followed by the other two conditions in random order, and biopsies for all trials were obtained at rest, after 15 min of exercise (15 min), and at the point of exhaustion during the LOW trial (49 min). BCOAD activity was not different among the three conditions at rest; however, at 15 min BCOAD activity was higher (P < or = 0.05) for the LOW (31 +/- 5%) and LOW+BCAA (43 +/- 11%) conditions compared with CON (12 +/- 1%). BCOAD activity at 49 min was not different from respective values at 15 min for any condition. These data indicate that BCOAD is rapidly activated during submaximal exercise under conditions associated with low carbohydrate availability. However, there was no relationship between BCOAD activity and glycogen concentration or net glycogenolysis, which suggests that factors other than glycogen availability are important for BCOAD regulation during exercise in humans.

  19. Planarian myosin essential light chain is involved in the formation of brain lateral branches during regeneration.

    PubMed

    Yu, Shuying; Chen, Xuhui; Yuan, Zuoqing; Zhou, Luming; Pang, Qiuxiang; Mao, Bingyu; Zhao, Bosheng

    2015-08-01

    The myosin essential light chain (ELC) is a structure component of the actomyosin cross-bridge, however, the functions in the central nervous system (CNS) development and regeneration remain poorly understood. Planarian Dugesia japonica has revealed fundamental mechanisms and unique aspects of neuroscience and neuroregeneration. In this study, the cDNA DjElc, encoding a planarian essential light chain of myosin, was identified from the planarian Dugesia japonica cDNA library. It encodes a deduced protein with highly conserved functionally domains EF-Hand and Ca(2+) binding sites that shares significant similarity with other members of ELC. Whole mount in situ hybridization studies show that DjElc expressed in CNS during embryonic development and regeneration of adult planarians. Loss of function of DjElc by RNA interference during planarian regeneration inhibits brain lateral branches regeneration completely. In conclusion, these results demonstrated that DjElc is required for maintenance of neurons and neurite outgrowth, particularly for involving the brain later branch regeneration.

  20. Diet treatment of branched chain ketoaciduria studied by proton magnetic resonance spectroscopy.

    PubMed

    Pontoni, G; Rotondo, F; Vacchiano, T M; Pinto, L; Perrotta, V; Pietra, D D; Cartenì-Farina, M; Zappia, V

    1996-03-01

    A novel nuclear magnetic resonance method is proposed for the diagnosis and follow-up of patients affected by branched chain ketoaciduria. The method allows quantitation of the branched chain amino acids (BCAA's) such as leucine, isoleucine and valine and of related keto- and hydroxy acids by means of a single spectrum. The method implies short time of analysis, as opposed to the very long time required by the techniques currently in use (amino acid analyzer combined with gaschromatography/mass spectrometry of keto- and hydroxyacids), it is easy and suitable for adjustements of the dietary treatment even on a daily basis. The case of a 15 days old newborn child, presenting muscular hypertonicity was unambiguously diagnosed in few minutes by means of one single NMR spectrum of urine. More interestingly, NMR spectra of serum in the following days were suitable for quantitating amino-, and keto acids as well as other metabolites of relevance in the follow up of the dietary treatment of the disease. After a diet lacking of BCAA's, to eliminate keto acids, a low BCAA diet was introduced, that succeeded in keeping the serum levels of the three amino acids within the normal range, while dropping the related keto acids.

  1. 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

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

    PubMed

    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

    2015-12-01

    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.

  3. Branched Chain Fatty Acids Are Constituents of the Normal Healthy Newborn Gastrointestinal Tract

    PubMed Central

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

    2008-01-01

    Vernix suspended in amniotic fluid is normally swallowed by the late term fetus. We hypothesized that branched chain fatty acids (BCFA), long known to be major vernix components, would be found in meconium and that the profiles would differ systematically. Vernix and meconium were collected from term newborns and analyzed. BCFA-containing lipids constituted about 12% of vernix dry weight, and were predominantly saturated, and had 11 to 26 carbons per BCFA. In contrast, meconium BCFA had 16 to 26 carbons, and was about 1% of dry weight. Meconium BCFA were mostly in the iso configuration, whereas vernix BCFA contained dimethyl and middle chain branching, and five anteiso BCFA. The mass of BCFA entering the fetal gut as swallowed vernix particles is estimated to be 180 mg in the last month of gestation while the total mass of BCFA found in meconium is estimated to be 16 mg, thus most BCFA disappear from the fetal gut. The BCFA profiles of vernix and meconium show that BCFA are major components of normal healthy term newborn gastrointestinal tract. BCFA are candidates for agents that play a role in gut colonization and should be considered a nutritional component for the fetus/newborn. PMID:18614964

  4. Physicochemical and tribophysical properties of trioctylalkylammonium bis(salicylato)borate (N888n-BScB) ionic liquids: effect of alkyl chain length.

    PubMed

    Gusain, Rashi; Bakshi, Paramjeet S; Panda, Somenath; Sharma, Om P; Gardas, Ramesh; Khatri, Om P

    2017-03-01

    The alkyl chain length of trioctylalkylammonium bis(salicylato)borates (N888n-BScB; n = 6, 8, 10 and 12) was varied to prepare a series of room-temperature ionic liquids, and then their viscosity and rheological properties were investigated. Besides the omnipresent Coulombic interactions, other interactive forces such as van der Waals interactions, hydrogen bonding, inductive forces, dipole-dipole interactions, etc., collectively determine the physicochemical properties of N888n-BScB ionic liquids. The van der Waals interactions and structural geometry of the ammonium cation (N888n) primarily organized the packing orientation of N888n-BScB ionic liquids and controlled their viscosity and rheological properties as a function of the alkyl chain length. The symmetric cation (N8888) increased the viscosity owing to closer packing driven by van der Waals interactions. The N888n-BScB ionic liquids exhibited non-Newtonian shear thinning behaviour. Furthermore, the decrease in viscosity at higher shear rates indicated that interactive forces in the N888n-BScB ionic liquids were disrupted. These ionic liquids, as lubricants, exhibited significantly lower friction (40-50%) and wear (45-69%) in comparison to PEG 300 synthetic lubricating oil. The degrees of reduction in friction and wear were largely influenced by the chain length of the alkyl group. The N888n-BScB ionic liquids with longer alkyl chains were strongly adsorbed on sliding surfaces and provided better lubrication properties than those with shorter alkyl chains. As a result, the coefficients of friction and wear were decreased by increasing the chain length in N888n-BScB ionic liquids. The tribologically induced adsorption of the BScB anion on metal surfaces, electrostatic interactions between ions, the compact and rigid structure of the BScB anion and van der Waals interactions provided by longer alkyl chains in the N888n cation collectively formed a tribochemical thin film of low shear strength, which resulted

  5. 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

  6. 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.

  7. Nonlinear rheology and strain recovery of short chain branched polyolefin elastomers and thermoplastic olefin blends

    NASA Astrophysics Data System (ADS)

    Patham, Bhaskar

    Polyolefin elastomers are random copolymers having a polyethylene backbone with the higher olefinic comonomer incorporated as short-chain branches. These random copolymers are widely used as polymer modifiers for thermoplastic materials such as polypropylenes, resulting in thermoplastic olefin (TPO) blends. This thesis addresses the nonlinear rheological behavior of the elastomers and then of the TPO blends. The effects of varying short chain branch density (SCB) on the melt rheology of three ethylene-octene random copolymers have been investigated. In particular, the strain-hardening behavior in extensional flow and strain recovery following nonlinear shear creep has been evaluated. The zero-shear viscosity followed trends in the backbone molecular weight closely. While the three copolymers were indistinguishable in linear viscoelastic creep and recovery, recovery following nonlinear shear creep decreased progressively with increasing SCB density. This reveals that the extent of rapid chain equilibration that occurs over Rouse time scales at higher strains was progressively lower with increasing SCB density. Strain hardening in uniaxial extensional flow was observed for all three copolymers. At strain rates below the primitive chain equilibration rates, strain hardening increases progressively with increasing SCB density. At higher rates, upon onset of primitive chain stretch, the strain hardening behavior for the three melts merges. Two thermoplastic olefin (TPO) blends were characterized in the context of injection molding; the surface morphology of injection molded tensile bars with these materials showed surface defects or flow marks to different extents. The flow marks were traced to different degrees of strain recovery in the dispersed phases of the two blends. This recovery occurred over injection molding timescales of the order of a few seconds. Strain recovery after shear creep was higher in the blend that displayed more severe flow marks in injection

  8. 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.

  9. Effects of odd-even side chain length of alkyl-substituted diphenylbithiophenes on first monolayer thin film packing structure.

    PubMed

    Akkerman, Hylke B; Mannsfeld, Stefan C B; Kaushik, Ananth P; Verploegen, Eric; Burnier, Luc; Zoombelt, Arjan P; Saathoff, Jonathan D; Hong, Sanghyun; Atahan-Evrenk, Sule; Liu, Xueliang; Aspuru-Guzik, Alán; Toney, Michael F; Clancy, Paulette; Bao, Zhenan

    2013-07-31

    Because of their preferential two-dimensional layer-by-layer growth in thin films, 5,5'bis(4-alkylphenyl)-2,2'-bithiophenes (P2TPs) are model compounds for studying the effects of systematic chemical structure variations on thin-film structure and morphology, which in turn, impact the charge transport in organic field-effect transistors. For the first time, we observed, by grazing incidence X-ray diffraction (GIXD), a strong change in molecular tilt angle in a monolayer of P2TP, depending on whether the alkyl chain on the P2TP molecules was of odd or even length. The monolayers were deposited on densely packed ultrasmooth self-assembled alkane silane modified SiO2 surfaces. Our work shows that a subtle change in molecular structure can have a significant impact on the molecular packing structure in thin film, which in turn, will have a strong impact on charge transport of organic semiconductors. This was verified by quantum-chemical calculations that predict a corresponding odd-even effect in the strength of the intermolecular electronic coupling.

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

    PubMed

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

    2014-03-14

    Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH2 + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH2) considered are acetamide (CH3CONH2), propionamide (CH3CH2CONH2), and butyramide (CH3CH2CH2CONH2); the electrolytes (LiX) are lithium perchlorate (LiClO4), lithium bromide (LiBr), and lithium nitrate (LiNO3). Differential scanning calorimetric measurements reveal glass transition temperatures (T(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(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 (CH3CONH2 + 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 terms of temporal heterogeneity and amide clustering in these multi-component melts.

  11. Alkyl group as entropy reservoir in an MMX chain complex, Pt2(n-PenCS2)4I.

    PubMed

    Saito, Kazuya; Ikeuchi, Satoaki; Nakazawa, Yasuhiro; Sato, Akane; Mitsumi, Minoru; Yamashita, Takami; Toriumi, Koshiro; Sorai, Michio

    2005-02-24

    Heat capacity of halogen-bridged one-dimensional binuclear metal complex (so-called MMX chain) having four n-pentyl groups, Pt2(n-PenCS2)4I, was measured by adiabatic calorimetry. A first-order phase transition was observed at 207.4 K when measurement was made after cooling from room temperature. The enthalpy and entropy of transition were determined to be 10.19 kJ mol(-1) and 49.1 J K(-1) mol(-1), respectively. A monotropic phase transition was observed at 324 K on heating, and the entropy of transition was essentially null. The sample once heated above 324 K never returned to the initial phase at room temperature and underwent a higher-order phase transition at 173 K and a first-order phase transition at 220.5 K. The enthalpy and entropy of the first-order phase transition were estimated to be 11.6 kJ mol(-1) and 52.4 J K(-1) mol(-1), respectively. The magnitude of the entropy gain at the phase transition from the initial room-temperature phase to the high-temperature phase at 324 K shows that in Pt2(n-PenCS2)4I a large amount of entropy reserved in alkyl chain is transferred to dithiocarboxylato groups upon the phase transition, as in the cases of Pt2(n-PrCS2)4I and Pt2(n-BuCS2)4I.

  12. Infrared Spectroscopy of Ionic Liquids Consisting of Imidazolium Cations with Different Alkyl Chain Lengths and Various Halogen or Molecular Anions with and Without a Small Amount of Water.

    PubMed

    Yamada, Toshiki; Tominari, Yukihiro; Tanaka, Shukichi; Mizuno, Maya

    2017-03-27

    Infrared spectroscopy was performed on ionic liquids (ILs) that had imidazolium cations with different alkyl chain lengths and various halogen or molecular anions with and without a small amount of water. The molar concentration normalized absorbance due to +C-H vibrational modes in the range of 3000 to 3200 cm-1 was nearly identical for ILs that had imidazolium cations with different alkyl chain lengths and the same anions. A close correlation was found between the red-shifted +C-H vibrational modes, the chemical shift of +C(2)-H proton, and the energy stabilization of hydrogen-bonding interaction. The vibrational modes of the water molecules interacting with anions in the range between 3300 and 3800 cm-1 was examined. The correlation between the vibrational frequencies of water, the frequencies of +C-H vibrational modes, and the center frequency of intermolecular vibrational modes due to ion pairs was discussed.

  13. Fermentative production of branched chain amino acids: a focus on metabolic engineering.

    PubMed

    Park, Jin Hwan; Lee, Sang Yup

    2010-01-01

    The branched chain amino acids (BCAAs), L-valine, L-leucine, and L-isoleucine, have recently been attracting much attention as their potential to be applied in various fields, including animal feed additive, cosmetics, and pharmaceuticals, increased. Strategies for developing microbial strains efficiently producing BCAAs are now in transition toward systems metabolic engineering from random mutagenesis. The metabolism and regulatory circuits of BCAA biosynthesis need to be thoroughly understood for designing system-wide metabolic engineering strategies. Here we review the current knowledge on BCAAs including their biosynthetic pathways, regulations, and export and transport systems. Recent advances in the development of BCAA production strains are also reviewed with a particular focus on L-valine production strain. At the end, the general strategies for developing BCAA overproducers by systems metabolic engineering are suggested.

  14. Study on color identification for monitoring and controlling fermentation process of branched chain amino acid

    NASA Astrophysics Data System (ADS)

    Ma, Lei; Wang, Yizhong; Chen, Ning; Liu, Tiegen; Xu, Qingyang; Kong, Fanzhi

    2008-12-01

    In this paper, a new method for monitoring and controlling fermentation process of branched chain amino acid (BCAA) was proposed based on color identification. The color image of fermentation broth of BCAA was firstly taken by a CCD camera. Then, it was changed from RGB color model to HIS color model. Its histograms of hue H and saturation S were calculated, which were used as the input of a designed BP network. The output of the BP network was the description of the color of fermentation broth of BCAA. After training, the color of fermentation broth was identified by the BP network according to the histograms of H and S of a fermentation broth image. Along with other parameters, the fermentation process of BCAA was monitored and controlled to start the stationary phase of fermentation soon. Experiments were conducted with satisfied results to show the feasibility and usefulness of color identification of fermentation broth in fermentation process control of BCAA.

  15. Inactivation of Gram-Positive Bacteria by Novel Phenolic Branched-Chain Fatty Acids.

    PubMed

    Fan, Xuetong; Wagner, Karen; Sokorai, Kimberly J B; Ngo, Helen

    2017-01-01

    Novel phenolic branched-chain fatty acids (PBC-FAs) were evaluated for their antimicrobial properties against both gram-positive ( Listeria innocua , Bacillus subtilis , Enterococcus faecium ) and gram-negative ( Escherichia coli , Salmonella Typhimurium, and Pseudomonas tolaasii ) bacteria. In addition, PBC-FA derivatives, such as PBC-FA methyl ester mixture, methyl-branched fatty acid mixtures, and trimethylsilyl-PBC-FA methyl esters, were synthesized to study the structure activity relationship. Results showed that PBC-FAs were a potent antimicrobial against gram-positive bacteria with MICs of 1.8 to 3.6 μg/ml. The compounds were less effective against gram-negative bacteria. Derivatives of PBC-FAs and an equimolar mixture of oleic acid and phenol all had MICs above 233 μg/ml against both gram-positive and gram-negative bacteria. Comparison of antimicrobial activities of the PBC-FAs with those of the derivatives suggests that the carboxylic group in the fatty acid moiety and the hydroxyl group on the phenol moiety were responsible for the antimicrobial efficacy. Growth curves of L. innocua revealed that PBC-FAs prevented bacterial growth, while MBC-FAs only delayed the onset of rapid growth of L. innocua . Our results demonstrated that the novel PBC-FAs have potential for use as antimicrobials against gram-positive bacteria.

  16. 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

  17. Metabolism of branched-chain keto acids in neonatal rat liver perfusions.

    PubMed

    Frost, S C; Wells, M A

    1983-10-15

    The ability of the neonatal rat to oxidize the branched-chain amino acids leucine and valine and their corresponding keto acids was evaluated. In vivo, about 20% of orally administered labeled amino or keto acids were oxidized in 6 h, after which time little further oxidation occurred. In perfused neonatal liver the amino acids were oxidized at only 5-10% the rate of the keto acids. The oxidation of the keto acids showed a saturable dependence on concentration. The decarboxylation of ketoisocaproate (KIC) had a maximal rate of 40.1 +/- 1.6 mumol/h/g liver with an apparent Km of 0.27 +/- 0.03 mM, and decarboxylation of ketoisovalerate (KIV) had a maximal rate of 37.9 +/- 1.9 mumol/h/g liver and an apparent Km of 0.28 +/- 0.04 mM. KIC was ketogenic, producing mainly acetoacetate at a maximal rate of 44.5 +/- 1.6 mumol/h/g liver with an apparent Km of 0.27 +/- 0.03 mM. On the other hand, KIV was not gluconeogenic, although the perfused neonatal liver was able to produce glucose from lactate. During liver perfusion, KIV did not produce measurable quantities of either propionic or beta-aminoisobutyric acids, which are possible end products of KIV metabolism. Decanoic acid inhibited the decarboxylation of both keto acids to the same extent with a maximal effect at 0.4 mM fatty acid. At saturating levels, KIC was less ketogenic than decanoate. Inhibition of endogenous fatty acid oxidation by 2-tetradecylglycidic acid had no effect on keto acid oxidation. These data suggest that branched-chain amino acids derived from milk proteins are probably not quantitatively significant sources of either ketone bodies or glucose in the neonatal rat.

  18. Benzothiophene Carboxylate Derivatives as Novel Allosteric Inhibitors of Branched-chain α-Ketoacid Dehydrogenase Kinase*

    PubMed Central

    Tso, Shih-Chia; Gui, Wen-Jun; Wu, Cheng-Yang; Chuang, Jacinta L.; Qi, Xiangbing; Skvorak, Kristen J.; Dorko, 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.

    2014-01-01

    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 (IC50 = 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 T½ = 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

  19. 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.

  20. Defective branched chain amino acid catabolism contributes to cardiac dysfunction and remodeling following myocardial infarction.

    PubMed

    Wang, Wei; Zhang, Fuyang; Xia, Yunlong; Zhao, Shihao; Yan, Wenjun; Wang, Helin; Lee, Yan; Li, Congye; Zhang, Ling; Lian, Kun; Gao, Erhe; Cheng, Hexiang; Tao, Ling

    2016-11-01

    Cardiac metabolic remodeling is a central event during heart failure (HF) development following myocardial infarction (MI). It is well known that myocardial glucose and fatty acid dysmetabolism contribute to post-MI cardiac dysfunction and remodeling. However, the role of amino acid metabolism in post-MI HF remains elusive. Branched chain amino acids (BCAAs) are an important group of essential amino acids and function as crucial nutrient signaling in mammalian animals. The present study aimed to determine the role of cardiac BCAA metabolism in post-MI HF progression. Utilizing coronary artery ligation-induced murine MI models, we found that myocardial BCAA catabolism was significantly impaired in response to permanent MI, therefore leading to an obvious elevation of myocardial BCAA abundance. In MI-operated mice, oral BCAA administration further increased cardiac BCAA levels, activated the mammalian target of rapamycin (mTOR) signaling, and exacerbated cardiac dysfunction and remodeling. These data demonstrate that BCAAs act as a direct contributor to post-MI cardiac pathologies. Furthermore, these BCAA-mediated deleterious effects were improved by rapamycin cotreatment, revealing an indispensable role of mTOR in BCAA-mediated adverse effects on cardiac function/structure post-MI. Of note, pharmacological inhibition of branched chain ketoacid dehydrogenase kinase (BDK), a negative regulator of myocardial BCAA catabolism, significantly improved cardiac BCAA catabolic disorders, reduced myocardial BCAA levels, and ameliorated post-MI cardiac dysfunction and remodeling. In conclusion, our data provide the evidence that impaired cardiac BCAA catabolism directly contributes to post-MI cardiac dysfunction and remodeling. Moreover, improving cardiac BCAA catabolic defects may be a promising therapeutic strategy against post-MI HF.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Shielding effects in polymer-polymer reactions. V. Concentration dependence of contact formation between star-branched and linear chains.

    PubMed

    Nardai, Michael M; Zifferer, Gerhard

    2013-07-19

    By use of the Dissipative Particle Dynamics (DPD) simulation technique mixtures of star-branched (arm number F = 4) and linear chains in athermal (good) solvent are analyzed regarding probabilities for intermolecular contacts of various reactive sites within different polymer coils. The accompanying sterical hindrances are described in the framework of shielding factors in order to investigate reactions and side reactions in radical polymerization and other techniques that involve polymer-polymer coupling. The shielding factors are studied as a function of total concentration from high dilution up to the bulk for different chain lengths of star-shaped and linear chains. Results indicate that their concentration dependence can be described by a power law for systems above the overlap concentration, whereas the chain length dependence vanishes when extrapolating to infinite chain lengths in that concentration range. Also the influence of the ratio of star chains and linear chains is studied for various concentrations.

  7. 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

  8. Molecular design of boronic acid-functionalized squarylium cyanine dyes for multiple discriminant analysis of sialic acid in biological samples: selectivity toward monosaccharides controlled by different alkyl side chain lengths.

    PubMed

    Ouchi, Kazuki; Colyer, Christa L; Sebaiy, Mahmoud; Zhou, Jin; Maeda, Takeshi; Nakazumi, Hiroyuki; Shibukawa, Masami; Saito, Shingo

    2015-02-03

    We designed a new series of boronic acid-functionalized squarylium cyanine dyes (SQ-BA) with different lengths of alkyl chain residues, suitable for multiple discriminant analysis (MDA) of sialic acid (Neu5Ac) in biological samples. The SQ-BA dyes form aggregates based on hydrophobic interactions, which result in quenched fluorescence in aqueous solutions. When the boronic acid binds with saccharides, the fluorescence intensity increases as a result of dissociation to the emissive monomeric complex. We inferred that different dye aggregate structures (H-aggregates and J-aggregates) were induced depending on the alkyl chain length, so that monosaccharides would be recognized in different ways (especially, multipoint interaction with J-aggregates). A distinctive emission enhancement of SQ-BA dyes with shorter-alkyl-chains in the presence of Neu5Ac was observed (2.4-fold fluorescence enhancement; with formation constant 10(1.7) M(-1)), with no such enhancement for SQ-BA dyes with longer-alkyl-chain. In addition, various enhancement factors for other monosaccharides were observed depending on the alkyl chain length. Detailed thermodynamic and NMR studies of the SQ-BA complexes revealed the unique recognition mechanism: the dye aggregate with a shorter-alkyl-chain causes the slipped parallel structure and forms a stable 2:1 complex with Neu5Ac, as distinct from longer-alkyl-chain dyes, which form a 1:1 monomeric complex. MDA using the four SQ-BA dyes was performed for human urine samples, resulting in the successful discrimination between normal and abnormal Neu5Ac levels characteristic of disease. Thus, we successfully controlled various responses to similar monosaccharides with a novel approach that chemically modified not the boronic acid moiety itself but the length of the alkyl chain residue attached to the dye in order to generate specificity.

  9. 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

  10. Branched short-chain fatty acids modulate glucose and lipid metabolism in primary adipocytes

    PubMed Central

    Heimann, Emilia; Nyman, Margareta; Pålbrink, Ann-Ki; Lindkvist-Petersson, Karin; Degerman, Eva

    2016-01-01

    ABSTRACT Short-chain fatty acids (SCFAs), e.g. acetic acid, propionic acid and butyric acid, generated through colonic fermentation of dietary fibers, have been shown to reach the systemic circulation at micromolar concentrations. Moreover, SCFAs have been conferred anti-obesity properties in both animal models and human subjects. Branched SCFAs (BSCFAs), e.g., isobutyric and isovaleric acid, are generated by fermentation of branched amino acids, generated from undigested protein reaching colon. However, BSCFAs have been sparsely investigated when referring to effects on energy metabolism. Here we primarily investigate the effects of isobutyric acid and isovaleric acid on glucose and lipid metabolism in primary rat and human adipocytes. BSCFAs inhibited both cAMP-mediated lipolysis and insulin-stimulated de novo lipogenesis at 10 mM, whereas isobutyric acid potentiated insulin-stimulated glucose uptake by all concentrations (1, 3 and 10 mM) in rat adipocytes. For human adipocytes, only SCFAs inhibited lipolysis at 10 mM. In both in vitro models, BSCFAs and SCFAs reduced phosphorylation of hormone sensitive lipase, a rate limiting enzyme in lipolysis. In addition, BSCFAs and SCFAs, in contrast to insulin, inhibited lipolysis in the presence of wortmannin, a phosphatidylinositide 3-kinase inhibitor and OPC3911, a phosphodiesterase 3 inhibitor in rat adipocytes. Furthermore, BSCFAs and SCFAs reduced insulin-mediated phosphorylation of protein kinase B. To conclude, BSCFAs have effects on adipocyte lipid and glucose metabolism that can contribute to improved insulin sensitivity in individuals with disturbed metabolism. PMID:27994949

  11. The acute toxic effects of imidazolium-based ionic liquids with different alkyl-chain lengths and anions on zebrafish (Danio rerio).

    PubMed

    Zhang, Cheng; Zhu, Lusheng; Wang, Jinhua; Wang, Jun; Zhou, Tongtong; Xu, Yaqi; Cheng, Chao

    2017-06-01

    With the increasing applications of ionic liquids (ILs), the toxicity of ILs has drawn increasing attention in recent years, especially the influences of different anions and alkyl-chain lengths on the acute toxicity to aquatic organisms. We performed a study on the acute toxicity of 1-alkyl-3-methylimidazolium nitrate ([Cnmim]NO3 (n=2, 4, 6, 8, 10, 12)), 1-hexyl-3-methylimidazolium ILs ([C6mim]R (R=Cl(-), Br(-), BF4(-), PF6(-))) to zebrafish (Danio rerio). We also evaluated the sensibility of the investigated animals and the stability of ILs in water via high performance liquid chromatography (HPLC, Agilent 1260, Agilent Technologies Inc., USA) to prove the reliability of the present study. The results illustrated that the test zebrafish (Danio rerio) were sensitive to the reference toxicant and that the investigated ILs in water were stable. The 50% lethal concentration (LC50) was used to represent the acute toxicity to zebrafish (Danio rerio). The present study showed that the highest toxic IL is [C12mim]NO3 and the lowest toxic IL is [C2mim]NO3 on Danio rerio. The LC50s for ILs with different anions had similar values. Accordingly, we believe that ILs with different alkyl-chain lengths cause greater effects than other anions on acute toxicity to aquatic organisms. Furthermore, the present study can also provide scientific methods for future studies to select and assess ILs.

  12. Mutation of zebrafish dihydrolipoamide branched-chain transacylase E2 results in motor dysfunction and models maple syrup urine disease.

    PubMed

    Friedrich, Timo; Lambert, Aaron M; Masino, Mark A; Downes, Gerald B

    2012-03-01

    Analysis of zebrafish mutants that demonstrate abnormal locomotive behavior can elucidate the molecular requirements for neural network function and provide new models of human disease. Here, we show that zebrafish quetschkommode (que) mutant larvae exhibit a progressive locomotor defect that culminates in unusual nose-to-tail compressions and an inability to swim. Correspondingly, extracellular peripheral nerve recordings show that que mutants demonstrate abnormal locomotor output to the axial muscles used for swimming. Using positional cloning and candidate gene analysis, we reveal that a point mutation disrupts the gene encoding dihydrolipoamide branched-chain transacylase E2 (Dbt), a component of a mitochondrial enzyme complex, to generate the que phenotype. In humans, mutation of the DBT gene causes maple syrup urine disease (MSUD), a disorder of branched-chain amino acid metabolism that can result in mental retardation, severe dystonia, profound neurological damage and death. que mutants harbor abnormal amino acid levels, similar to MSUD patients and consistent with an error in branched-chain amino acid metabolism. que mutants also contain markedly reduced levels of the neurotransmitter glutamate within the brain and spinal cord, which probably contributes to their abnormal spinal cord locomotor output and aberrant motility behavior, a trait that probably represents severe dystonia in larval zebrafish. Taken together, these data illustrate how defects in branched-chain amino acid metabolism can disrupt nervous system development and/or function, and establish zebrafish que mutants as a model to better understand MSUD.

  13. Genomic analysis of branched chain fatty acid and acyl sugar production in Solanum pennellii and Nicotiana benthamiana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acyl sugars are extracellular epidermal lipids that are exuded from glandular trichomes and coat the aerial organs of many species in the Solanaceae. These highly viscous surfactants, which often contain branched-chain fatty acids (BCFA), play an important defensive role against pest and insects. ...

  14. 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...

  15. 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...

  16. 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...

  17. Monomethyl Branched-Chain Fatty Acids Play an Essential Role in Caenorhabditis elegans Development

    PubMed Central

    Crawford, Quinn T; Seiber, Matt; Wang, Cun-Yu

    2004-01-01

    Monomethyl branched-chain fatty acids (mmBCFAs) are commonly found in many organisms from bacteria to mammals. In humans, they have been detected in skin, brain, blood, and cancer cells. Despite a broad distribution, mmBCFAs remain exotic in eukaryotes, where their origin and physiological roles are not understood. Here we report our study of the function and regulation of mmBCFAs in Caenorhabditis elegans, combining genetics, gas chromatography, and DNA microarray analysis. We show that C. elegans synthesizes mmBCFAs de novo and utilizes the long-chain fatty acid elongation enzymes ELO-5 and ELO-6 to produce two mmBCFAs, C15ISO and C17ISO. These mmBCFAs are essential for C. elegans growth and development, as suppression of their biosynthesis results in a growth arrest at the first larval stage. The arrest is reversible and can be overcome by feeding the arrested animals with mmBCFA supplements. We show not only that the levels of C15ISO and C17ISO affect the expression of several genes, but also that the activities of some of these genes affect biosynthesis of mmBCFAs, suggesting a potential feedback regulation. One of the genes, lpd-1, encodes a homolog of a mammalian sterol regulatory element-binding protein (SREBP 1c). We present results suggesting that elo-5 and elo-6 may be transcriptional targets of LPD-1. This study exposes unexpected and crucial physiological functions of C15ISO and C17ISO in C. elegans and suggests a potentially important role for mmBCFAs in other eukaryotes. PMID:15340492

  18. Branched-chain and aromatic amino acid catabolism into aroma volatiles in Cucumis melo L. fruit.

    PubMed

    Gonda, Itay; Bar, Einat; Portnoy, Vitaly; Lev, Shery; Burger, Joseph; Schaffer, Arthur A; Tadmor, Ya'akov; Gepstein, Shimon; Giovannoni, James J; Katzir, Nurit; Lewinsohn, Efraim

    2010-02-01

    The unique aroma of melons (Cucumis melo L., Cucurbitaceae) is composed of many volatile compounds biosynthetically derived from fatty acids, carotenoids, amino acids, and terpenes. Although amino acids are known precursors of aroma compounds in the plant kingdom, the initial steps in the catabolism of amino acids into aroma volatiles have received little attention. Incubation of melon fruit cubes with amino acids and alpha-keto acids led to the enhanced formation of aroma compounds bearing the side chain of the exogenous amino or keto acid supplied. Moreover, L-[(13)C(6)]phenylalanine was also incorporated into aromatic volatile compounds. Amino acid transaminase activities extracted from the flesh of mature melon fruits converted L-isoleucine, L-leucine, L-valine, L-methionine, or L-phenylalanine into their respective alpha-keto acids, utilizing alpha-ketoglutarate as the amine acceptor. Two novel genes were isolated and characterized (CmArAT1 and CmBCAT1) encoding 45.6 kDa and 42.7 kDa proteins, respectively, that displayed aromatic and branched-chain amino acid transaminase activities, respectively, when expressed in Escherichia coli. The expression of CmBCAT1 and CmArAT1 was low in vegetative tissues, but increased in flesh and rind tissues during fruit ripening. In addition, ripe fruits of climacteric aromatic cultivars generally showed high expression of CmBCAT1 and CmArAT1 in contrast to non-climacteric non-aromatic fruits. The results presented here indicate that in melon fruit tissues, the catabolism of amino acids into aroma volatiles can initiate through a transamination mechanism, rather than decarboxylation or direct aldehyde synthesis, as has been demonstrated in other plants.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. Engineering biosynthetic pathways for deoxysugars: branched-chain sugar pathways and derivatives from the antitumor tetracenomycin.

    PubMed

    Lombó, Felipe; Gibson, Miranda; Greenwell, Lisa; Braña, Alfredo F; Rohr, Jürgen; Salas, José A; Méndez, Carmen

    2004-12-01

    Sugar biosynthesis cassette genes have been used to construct plasmids directing the biosynthesis of branched-chain deoxysugars: pFL942 (NDP-L-mycarose), pFL947 (NDP-4-deacetyl-L-chromose B), and pFL946/pFL954 (NDP-2,3,4-tridemethyl-L-nogalose). Expression of pFL942 and pFL947 in S. lividans 16F4, which harbors genes for elloramycinone biosynthesis and the flexible ElmGT glycosyltransferase of the elloramycin biosynthetic pathway, led to the formation of two compounds: 8-alpha-L-mycarosyl-elloramycinone and 8-demethyl-8-(4-deacetyl)-alpha-L-chromosyl-tetracenomycin C, respectively. Expression of pFL946 or pFL954 failed to produce detectable amounts of a novel glycosylated tetracenomycin derivative. Formation of these two compounds represents examples of the sugar cosubstrate flexibility of the ElmGT glycosyltransferase. The use of these cassette plasmids also provided insights into the substrate flexibility of deoxysugar biosynthesis enzymes as the C-methyltransferases EryBIII and MtmC, the epimerases OleL and EryBVII, and the 4-ketoreductases EryBIV and OleU.

  5. 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

  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. Efficacy, Dosage, and Duration of Action of Branched Chain Amino Acid Therapy for Traumatic Brain Injury

    PubMed Central

    Elkind, Jaclynn A.; Lim, Miranda M.; Johnson, Brian N.; Palmer, Chris P.; Putnam, Brendan J.; Kirschen, Matthew P.; Cohen, Akiva S.

    2015-01-01

    Traumatic brain injury (TBI) results in long-lasting cognitive impairments for which there is currently no accepted treatment. A well-established mouse model of mild to moderate TBI, lateral fluid percussion injury (FPI), shows changes in network excitability in the hippocampus including a decrease in net synaptic efficacy in area CA1 and an increase in net synaptic efficacy in dentate gyrus. Previous studies identified a novel therapy consisting of branched chain amino acids (BCAAs), which restored normal mouse hippocampal responses and ameliorated cognitive impairment following FPI. However, the optimal BCAA dose and length of treatment needed to improve cognitive recovery is unknown. In the current study, mice underwent FPI then consumed 100 mM BCAA supplemented water ad libitum for 2, 3, 4, 5, and 10 days. BCAA therapy ameliorated cognitive impairment at 5 and 10 days duration. Neither BCAA supplementation at 50 mM nor BCAAs when dosed 5 days on then 5 days off was sufficient to ameliorate cognitive impairment. These results suggest that brain injury causes alterations in hippocampal function, which underlie and contribute to hippocampal cognitive impairment, which are reversible with at least 5 days of BCAA treatment, and that sustaining this effect is dependent on continuous treatment. Our findings have profound implications for the clinical investigation of TBI therapy. PMID:25870584

  8. Vibrational nonequilibrium in chain branching reactions of hydrogen combustion using quasi-classical trajectory analysis

    NASA Astrophysics Data System (ADS)

    Voelkel, Stephen; Raman, Venkat; Varghese, Philip

    2015-11-01

    In high-speed reactive flows in scramjets, thermal nonequilibrium is introduced in the flow via shock waves. Though rotational and translational energy modes relax back to equilibrium quickly, vibrational relaxation is comparable to the bulk mixing and reaction timescales. The discrepancy between vibration and rotation/translation energy distributions can dramatically alter on the initiation of the fuel oxidation process. For continuum-scale applications, thermal nonequilibrium effects are derived from the rovibrational state-specific reaction and scattering rates associated with the chemical mechanism. In this work, the state-specific reaction rates are calculated for the chain branching reactions in the hydrogen combustion mechanism using a quasi-classical trajectory (QCT) framework. The state-specific rates are incorporated into a multiple temperature continuum-scale model whereby each species is characterized by a Boltzmann distribution parametrized by its own vibrational temperature. The flame ignition rates are implemented in a CFD code to simulate a reactive coflow. Funded by AFOSR FA9550-12-1-0460.

  9. Transamination of branched chain amino acids (BCAA) in rat adipose tissue

    SciTech Connect

    Frick, G.P.; Goodman, H.M.

    1986-03-05

    Like most extrahepatic tissues, adipose tissue can transaminate the BCAA faster than they are oxidized. Catabolism of the BCAA by adipose tissue appears to be limited by the activity of branched chain ..cap alpha..-keto acid dehydrogenase (BCDH). Conditions which stimulate the activity of this intramitochondrial enzyme in tissue extracts also increase the rate at which (1-/sup 14/C)leucine (L) and (1-/sup 14/C)valine (V) are oxidized by tissue segments. However, when maximum rates of oxidation were measured, 10 mM L was oxidized to /sup 14/CO/sub 2/ 5 times faster than 10 mM V (30 +/- 2 vs. 6 +/- 1 nmol min/sup -1/ g tis/sup -1/). In contrast, the ..cap alpha..-keto analogs of L and V were oxidized by tissue segments at nearly equal rates which slightly exceeded the rate of L oxidation. These results suggested that transamination might limit the catabolism of V, perhaps due to its inaccessibility to transaminase. The distribution of transaminase activity in tissue extracts was determined after centrifugation to obtain mitochondrial and cytosolic fractions. L and V were transaminated at similar rates by enzymes in both fractions. Transaminase activity in the mitochondrial fraction was greater than that of the cytosol and exceeded the capacity of the tissue to oxidize L. Catabolism of BCAA may depend upon intramitochondrial transamination and oxidation of V may be slower than that of L because uptake of V by mitochondria may be slower than that of L.

  10. Branched-chain amino acid supplementation promotes aerobic growth of Salmonella Typhimurium under nitrosative stress conditions.

    PubMed

    Park, Yoon Mee; Lee, Hwa Jeong; Jeong, Jae-Ho; Kook, Joong-Ki; Choy, Hyon E; Hahn, Tae-Wook; Bang, Iel Soo

    2015-12-01

    Nitric oxide (NO) inactivates iron-sulfur enzymes in bacterial amino acid biosynthetic pathways, causing amino acid auxotrophy. We demonstrate that exogenous supplementation with branched-chain amino acids (BCAA) can restore the NO resistance of hmp mutant Salmonella Typhimurium lacking principal NO-metabolizing enzyme flavohemoglobin, and of mutants further lacking iron-sulfur enzymes dihydroxy-acid dehydratase (IlvD) and isopropylmalate isomerase (LeuCD) that are essential for BCAA biosynthesis, in an oxygen-dependent manner. BCAA supplementation did not affect the NO consumption rate of S. Typhimurium, suggesting the BCAA-promoted NO resistance independent of NO metabolism. BCAA supplementation also induced intracellular survival of ilvD and leuCD mutants at wild-type levels inside RAW 264.7 macrophages that produce constant amounts of NO regardless of varied supplemental BCAA concentrations. Our results suggest that the NO-induced BCAA auxotrophy of Salmonella, due to inactivation of iron-sulfur enzymes for BCAA biosynthesis, could be rescued by bacterial taking up exogenous BCAA available in oxic environments.

  11. Novel metabolic and physiological functions of branched chain amino acids: a review.

    PubMed

    Zhang, Shihai; Zeng, Xiangfang; Ren, Man; Mao, Xiangbing; Qiao, Shiyan

    2017-01-01

    It is widely known that branched chain amino acids (BCAA) are not only elementary components for building muscle tissue but also participate in increasing protein synthesis in animals and humans. BCAA (isoleucine, leucine and valine) regulate many key signaling pathways, the most classic of which is the activation of the mTOR signaling pathway. This signaling pathway connects many diverse physiological and metabolic roles. Recent years have witnessed many striking developments in determining the novel functions of BCAA including: (1) Insufficient or excessive levels of BCAA in the diet enhances lipolysis. (2) BCAA, especially isoleucine, play a major role in enhancing glucose consumption and utilization by up-regulating intestinal and muscular glucose transporters. (3) Supplementation of leucine in the diet enhances meat quality in finishing pigs. (4) BCAA are beneficial for mammary health, milk quality and embryo growth. (5) BCAA enhance intestinal development, intestinal amino acid transportation and mucin production. (6) BCAA participate in up-regulating innate and adaptive immune responses. In addition, abnormally elevated BCAA levels in the blood (decreased BCAA catabolism) are a good biomarker for the early detection of obesity, diabetes and other metabolic diseases. This review will provide some insights into these novel metabolic and physiological functions of BCAA.

  12. 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.

  13. Branched-chain amino acids enhance cyst development in autosomal dominant polycystic kidney disease.

    PubMed

    Yamamoto, Junya; Nishio, Saori; Hattanda, Fumihiko; Nakazawa, Daigo; Kimura, Toru; Sata, Michio; Makita, Minoru; Ishikawa, Yasunobu; Atsumi, Tatsuya

    2017-03-21

    Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the progressive development of kidney and liver cysts. The mammalian target of rapamycin (mTOR) cascade is one of the important pathways regulating cyst growth in ADPKD. Branched-chain amino acids (BCAAs), including leucine, play a crucial role to activate mTOR pathway. Therefore, we administered BCAA dissolved in the drinking water to Pkd1(flox/flox):Mx1-Cre (cystic) mice from four to 22 weeks of age after polyinosinic-polycytidylic acid-induced conditional Pkd1 knockout at two weeks of age. The BCAA group showed significantly greater kidney/body weight ratio and higher cystic index in both the kidney and liver compared to the placebo-treated mice. We found that the L-type amino acid transporter 1 that facilitates BCAA entry into cells is strongly expressed in cells lining the cysts. We also found increased cyst-lining cell proliferation and upregulation of mTOR and mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathways in the BCAA group. In vitro, we cultured renal epithelial cell lines from Pkd1 null mice with or without leucine. Leucine was found to stimulate cell proliferation, as well as activate mTOR and MAPK/ERK pathways in these cells. Thus, BCAA accelerated disease progression by mTOR and MAPK/ERK pathways. Hence, BCAA may be harmful to patients with ADPKD.

  14. Branched-chain amino acids and ammonia metabolism in liver disease: therapeutic implications.

    PubMed

    Holecek, Milan

    2013-10-01

    The rationale for recommendation of branched-chain amino acids (BCAA; valine, leucine, and isoleucine) in treatment of liver failure is based on their unique pharmacologic properties, stimulatory effect on ammonia detoxification to glutamine (GLN), and decreased concentrations in liver cirrhosis. Multiple lines of evidence have shown that the main cause of the BCAA deficiency in liver cirrhosis is their consumption in skeletal muscle for synthesis of glutamate, which acts as a substrate for ammonia detoxification to GLN and that the BCAA administration to patients with liver failure may exert a number of positive effects that may be more pronounced in patients with marked depression of BCAA levels. On the other hand, due to the stimulatory effect of BCAA on GLN synthesis, BCAA supplementation may lead to enhanced ammonia production from GLN breakdown in the intestine and the kidneys and thus exert harmful effects on the development of hepatic encephalopathy. Therefore, to enhance therapeutic effectiveness of the BCAA in patients with liver injury, their detrimental effect on ammonia production, which is negligible in healthy people and/or patients with other disorders, should be avoided. In treatment of hepatic encephalopathy, simultaneous administration of the BCAA (to correct amino acid imbalance and promote ammonia detoxification to GLN) with α-ketoglutarate (to inhibit GLN breakdown to ammonia in enterocytes) and/or phenylbutyrate (to enhance GLN excretion by the kidneys) is suggested. Attention should be given to the type of liver injury, gastrointestinal bleeding, signs of inflammation, and the dose of BCAA.

  15. 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.

  16. Modulation of absence seizures by branched-chain amino acids: correlation with brain amino acid concentrations.

    PubMed

    Dufour, F; Nalecz, K A; Nalecz, M J; Nehlig, A

    2001-07-01

    The occurrence of absence seizures might be due to a disturbance of the balance between excitatory and inhibitory neurotransmissions in the thalamo-cortical loop. In this study, we explored the consequences of buffering the glutamate content of brain cells on the occurrence and duration of seizures in Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a genetic model of generalized non-convulsive epilepsy. Branched-chain amino acids (BCAAs) and alpha-ketoisocaproate (alpha-KIC), the ketoacid of leucine were repeatedly shown to have a critical role in brain glutamate metabolism. Thus, GAERS were injected by intraperitoneal (i.p.) or intracerebroventricular (i.c.v.) route with these compounds, then the effects on seizures were evaluated on the electroencephalographic recording. We also measured the concentration of amino acids in thalamus and cortex after an i.p. injection of leucine or alpha-KIC. Intracerebroventricular injections of leucine or alpha-KIC did not influence the occurrence of seizures, possibly because the substances reached only the cortex. BCAAs and alpha-KIC, injected intraperitoneally, increased the number of seizures whereas they had only a slight effect on their duration. Leucine and alpha-KIC decreased the concentration of glutamate in thalamus and cortex without affecting GABA concentrations. Thus, BCAAs and alpha-KIC, by decreasing the effects of glutamatergic neurotransmission could facilitate those of GABAergic neurotransmission, which is known to increase the occurrence of seizures in GAERS.

  17. Elevated circulating branched chain amino acids are an early event in pancreatic adenocarcinoma development

    PubMed Central

    Kraft, Peter; Torrence, Margaret E.; Fiske, Brian P.; Yuan, Chen; Bao, Ying; Townsend, Mary K.; Tworoger, Shelley S.; Davidson, Shawn M.; Papagiannakopoulos, Thales; Yang, Annan; Dayton, Talya L.; Ogino, Shuji; Stampfer, Meir J.; Giovannucci, Edward L.; Qian, Zhi Rong; Rubinson, Douglas A.; Ma, Jing; Sesso, Howard D.; Gaziano, John Michael; Cochrane, Barbara B.; Liu, Simin; Wactawski–Wende, Jean; Manson, JoAnn E.; Pollak, Michael N.; Kimmelman, Alec C.; Souza, Amanda; Pierce, Kerry; Wang, Thomas J.; Gerszten, Robert E.; Fuchs, Charles S.; Heiden, Matthew G. Vander; Wolpin, Brian M.

    2014-01-01

    Most patients with pancreatic ductal adenocarcinoma (PDAC) are diagnosed with advanced disease and survive less than 12 months1. PDAC has been linked with obesity and glucose intolerance2-4, but whether changes in circulating metabolites are associated with early cancer progression is unknown. To better understand metabolic derangements associated with early disease, we profiled metabolites in prediagnostic plasma from pancreatic cancer cases and matched controls from four prospective cohort studies. We find that elevated plasma levels of branched chain amino acids (BCAAs) are associated with a greater than 2–fold increased risk of future pancreatic cancer diagnosis. This elevated risk was independent of known predisposing factors, with the strongest association observed among subjects with samples collected 2 to 5 years prior to diagnosis when occult disease is likely present. We show that plasma BCAAs are also elevated in mice with early stage pancreatic cancers driven by mutant Kras expression, and that breakdown of tissue protein accounts for the increase in plasma BCAAs that accompanies early stage disease. Together, these findings suggest that increased whole–body protein breakdown is an early event in development of PDAC. PMID:25261994

  18. 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

  19. Synthesis and characterization of a novel long-alkyl-chain ester-substituted benzimidazole gelator and its octan-1-ol solvate.

    PubMed

    Geiger, H Cristina; Zick, Patricia L; Roberts, William R; Geiger, David K

    2017-04-01

    The synthesis of a novel benzimidazole derivative with a long-chain-ester substituent, namely methyl 8-[4-(1H-benzimidazol-2-yl)phenoxy]octanoate, (3), is reported. Ester (3) shows evidence of aggregation in solution and weak gelation ability with toluene. The octan-1-ol solvate, methyl 8-[4-(1H-benzimidazol-2-yl)phenoxy]octanoate octan-1-ol monosolvate, C22H26N2O3·C8H18O, (4), exhibits a four-molecule hydrogen-bonded motif in the solid state, with N-H...O hydrogen bonds between benzimidazole molecules and O-H...N hydrogen bonds between the octan-1-ol solvent molecules and the benzimidazole unit. The alkyl chains of the ester and the octan-1-ol molecules are in unfolded conformations. The phenylene ring is canted by 10.27 (6)° from the plane of the benzimidazole ring system. H...C contacts make up 20.7% of the Hirshfeld surface coverage. Weak C-H...π interactions involving the benzimidazole alkyl chain and three aromatic rings are observed.

  20. Time-Resolved EPR Study of Electron-Hole Dissociations Influenced by Alkyl Side Chains at the Photovoltaic Polyalkylthiophene:PCBM Interface.

    PubMed

    Miura, Taku; Aikawa, Motoko; Kobori, Yasuhiro

    2014-01-02

    Nanosecond time-resolved electron paramagnetic resonance (TREPR) spectroscopy has been utilized at T = 77 K to characterize alkyl side-chain effects on geometries and on the electronic couplings (VCR) of transient charge-separated (CS) states in the photoactive layers fabricated by the spin-coating of mixed solutions of regioregular polyalkylthiophenes (RR-P3AT) and [6,6]-C61-butyric acid methyl ester (PCBM). By increasing the alkyl side-chain number from 6 to 12 in P3AT, a highly distant and long-lived CS state has been obtained. This result is explained by a coupling of the hole dissociation to the polymer librations by the side-chains. From an exponential decay of VCR with respect to the CS distance, the attenuation factor (βe) has been determined to be βe = 0.2 Å(-1). Such a long-range tunneling feature is explained by the generations of the shallowly trapped, delocalized electron-hole pairs by the dissociation of the hole toward π-stacking directions at the organic photovoltaic interface.

  1. Hydrogen migrations in alkylcycloalkyl radicals: implications for chain-branching reactions in fuels.

    PubMed

    Davis, Alexander C; Tangprasertchai, Narin; Francisco, Joseph S

    2012-09-03

    A thorough understanding of the oxidation chemistry of cycloalkanes is integral to the development of alternative fuels and improving current fuel performance. An important class of reactions essential to this chemistry is the hydrogen migration; however, they have largely been omitted from the literature for cycloalkanes. The present work investigates all of the hydrogen migration reactions available to methylcyclopentane, ethylcyclopentane, methylcyclohexane, and ethylcyclohexane. The kinetic and thermodynamic parameters have been studied by a combination of computational methods and compared to their corresponding n-alkyl and methylalkyl counterparts to determine the effect that the cycloalkane ring has on these reactions. In particular, although the alkylcycloalkyl activation energies for the dominant 1,4, 1,5, and 1,6 H-migration are higher than in n-alkyl and methylalkyl radicals, because several of the rotors needed to form the transition state are locked into place as part of the cycloalkane ring, the A-factors are higher for the alkylcycloalkyl reactions, making the rates closer to the noncyclic systems, at higher temperatures. The results presented here suggest that the relative importance of each H-migration pathway differs from the trends predicted by either the n-alkyl or methylalkyl radical systems. Of particular interest is the observation that since the barrier height of the 1,4 H-migration is only 3-5 kcal mol(-1) higher than the 1,5 H-migration in the methyl and ethylcycloalkyl radicals, compared to a difference of roughly 7 kcal mol(-1) in similar reactions for both the n-alkyl and methylalkyl radicals, the 1,4 H-migrations in alkylcycloalkyl radicals will be more important in the overall mechanism than would be predicted based on the n-alkyl and methylalkyl radicals. These results have important combustion model implications, particularly for fuels with high cycloalkane content.

  2. BRANCHED-CHAIN AMINOTRANSFERASE4 Is Part of the Chain Elongation Pathway in the Biosynthesis of Methionine-Derived Glucosinolates in Arabidopsis[W

    PubMed Central

    Schuster, Joachim; Knill, Tanja; Reichelt, Michael; Gershenzon, Jonathan; Binder, Stefan

    2006-01-01

    As part of our analysis of branched-chain amino acid metabolism in plants, we analyzed the function of Arabidopsis thaliana BRANCHED-CHAIN AMINOTRANSFERASE4 (BCAT4). Recombinant BCAT4 showed high efficiency with Met and its derivatives and the corresponding 2-oxo acids, suggesting its participation in the chain elongation pathway of Met-derived glucosinolate biosynthesis. This was substantiated by in vivo analysis of two BCAT4 T-DNA knockout mutants, in which Met-derived aliphatic glucosinolate accumulation is reduced by ∼50%. The increase in free Met and S-methylmethionine levels in these mutants, together with in vitro substrate specificity, strongly implicate BCAT4 in catalysis of the initial deamination of Met to 4-methylthio-2-oxobutyrate. BCAT4 transcription is induced by wounding and is predominantly observed in the phloem. BCAT4 transcript accumulation also follows a diurnal rhythm, and green fluorescent protein tagging experiments and subcellular protein fractions show that BCAT4 is located in the cytosol. The assignment of BCAT4 to the Met chain elongation pathway documents the close evolutionary relationship of this pathway to Leu biosynthesis. In addition to BCAT4, the enzyme methylthioalkylmalate synthase 1 has been recruited for the Met chain elongation pathway from a gene family involved in Leu formation. This suggests that the two pathways have a common evolutionary origin. PMID:17056707

  3. 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.

  4. Advances and challenges in the treatment of branched-chain amino/keto acid metabolic defects

    PubMed Central

    Weinhold, Natalie; Vockley, Jerry; Gibson, K. Michael

    2014-01-01

    Summary Disorders of branched-chain amino/keto acid metabolism encompass diverse entities, including maple syrup urine disease (MSUD), the ‘classical’ organic acidurias isovaleric acidemia (IVA), propionic acidemia (PA), methylmalonic acidemia (MMA) and, among others, rarely described disorders such as 2-methylbutyryl-CoA dehydrogenase deficiency (MBDD) or isobutyryl-CoA dehydrogenase deficiency (IBDD). Our focus in this review is to highlight the biochemical basis underlying recent advances and ongoing challenges of long-term conservative therapy including precursor/protein restriction, replenishment of deficient substrates, and the use of antioxidants and anaplerotic agents which refill the Krebs cycle. Ongoing clinical assessments of affected individuals in conjunction with monitoring of disease-specific biochemical parameters remain essential. It is likely that mass spectrometry-based ‘metabolomics’ may be a helpful tool in the future for studying complete biochemical profiles and diverse metabolic phenotypes. Prospective studies are needed to test the effectiveness of adjunct therapies such as antioxidants, ornithine-alpha-ketoglutarate (OKG) or creatine in addition to specialized diets and to optimize current therapeutic strategies in affected individuals. With the individual lifetime risk and degree of severity being unknown in asymptomatic individuals with MBDD or IBDD, instructions regarding risks for metabolic stress and fasting avoidance along with clinical monitoring are reasonable interventions at the current time. Overall, it is apparent that carefully designed prospective clinical investigations and multicenter cohort-controlled trials are needed in order to leverage that knowledge into significant breakthroughs in treatment strategies and appropriate approaches. PMID:21290185

  5. 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.

  6. C4'-Branched-chain surgar nucleosides: synthesis of isomers of psicofuranine.

    PubMed

    Rosenthal, A; Ratcliffe, M

    1977-03-01

    Photoamidation of 3-O-acetyl-1,2:5,6-di-O-isopropylidene-alpha-D-erythro-hex-3-enofuranose (1) afforded 3-O-acetyl-4-C-carbamoyl-1,2:5,6-di-O-isopropylidene-alpha-D-gulofuranose (2) and 3-O-acetyl-3-C-carbamoyl-1,2:5,6-di-O-isopropylidene-D-alpha-allofuranose (3) in 65 and 26% yields, respectively (based on consumed 1). Treatment of 2 and 5% hydrochloric acid in methanol yielded the spiro lactone 5, which was deacetylated to yield 7. Reduction of 5 with sodium borohydride afforded 4-C-(hydroxymethyl)-1,2-O-isopropylidene-alpha-D-gulofuranose (9) in 79% yield. Oxidation of 9 with sodium metaperiodate afforded a dialdose that was reduced with sodium borohydride to give 4-C-(hydroxymethyl)-1,2-O-isopropylidene-alpha-D-erythro-pentofuranose (11) in 88% yield. Treatment of the acetate 12, derived from 11, with trifluoroacetic acid, followed by acetylation, afforded the branched-chain sugar acetate 14. Condensation of the glycosyl halide derived from 14 with N6-benzoyl-N6,9-bis-(trimethylsilyl)adenine yielded an equimolar anomeric mixture of protected nucleosides 15 and 16 in 40% yield. Treatment of the latter compounds with sodium methoxide in methanol afforded 9-[4-C-(hydroxymethyl)-beta-D-erythro-pentofuranosyl] adenine (17) and the alpha-D anomer 18. The structure of 3 was determined by correlation with the known 5,3'-hemiacetal of 3-C-(hydroxymethyl)-1,2-O-isopropylidene-alpha,alpha'-D-ribo-pentodialdose (25).

  7. Altered Expression of Human Mitochondrial Branched Chain Aminotransferase in Dementia with Lewy Bodies and Vascular Dementia.

    PubMed

    Ashby, Emma L; Kierzkowska, Marta; Hull, Jonathon; Kehoe, Patrick G; Hutson, Susan M; Conway, Myra E

    2017-01-01

    Cytosolic and mitochondrial human branched chain aminotransferase (hBCATc and hBCATm, respectively) play an integral role in brain glutamate metabolism. Regional increased levels of hBCATc in the CA1 and CA4 region of Alzheimer's disease (AD) brain together with increased levels of hBCATm in frontal and temporal cortex of AD brains, suggest a role for these proteins in glutamate excitotoxicity. Glutamate toxicity is a key pathogenic feature of several neurological disorders including epilepsy associated dementia, AD, vascular dementia (VaD) and dementia with Lewy bodies (DLB). To further understand if these increases are specific to AD, the expression profiles of hBCATc and hBCATm were examined in other forms of dementia including DLB and VaD. Similar to AD, levels of hBCATm were significantly increased in the frontal and temporal cortex of VaD cases and in frontal cortex of DLB cases compared to controls, however there were no observed differences in hBCATc between groups in these areas. Moreover, multiple forms of hBCATm were observed that were particular to the disease state relative to matched controls. Real-time PCR revealed similar expression of hBCATm mRNA in frontal and temporal cortex for all cohort comparisons, whereas hBCATc mRNA expression was significantly increased in VaD cases compared to controls. Collectively our results suggest that hBCATm protein expression is significantly increased in the brains of DLB and VaD cases, similar to those reported in AD brain. These findings indicate a more global response to altered glutamate metabolism and suggest common metabolic responses that might reflect shared neurodegenerative mechanisms across several forms of dementia.

  8. Adipose tissue branched chain amino acid (BCAA) metabolism modulates circulating BCAA levels.

    PubMed

    Herman, Mark A; She, Pengxiang; Peroni, Odile D; Lynch, Christopher J; Kahn, Barbara B

    2010-04-09

    Whereas the role of adipose tissue in glucose and lipid homeostasis is widely recognized, its role in systemic protein and amino acid metabolism is less well-appreciated. In vitro and ex vivo experiments suggest that adipose tissue can metabolize substantial amounts of branched chain amino acids (BCAAs). However, the role of adipose tissue in regulating BCAA metabolism in vivo is controversial. Interest in the contribution of adipose tissue to BCAA metabolism has been renewed with recent observations demonstrating down-regulation of BCAA oxidation enzymes in adipose tissue in obese and insulin-resistant humans. Using gene set enrichment analysis, we observe alterations in adipose-tissue BCAA enzyme expression caused by adipose-selective genetic alterations in the GLUT4 glucose-transporter expression. We show that the rate of adipose tissue BCAA oxidation per mg of tissue from normal mice is higher than in skeletal muscle. In mice overexpressing GLUT4 specifically in adipose tissue, we observe coordinate down-regulation of BCAA metabolizing enzymes selectively in adipose tissue. This decreases BCAA oxidation rates in adipose tissue, but not in muscle, in association with increased circulating BCAA levels. To confirm the capacity of adipose tissue to modulate circulating BCAA levels in vivo, we demonstrate that transplantation of normal adipose tissue into mice that are globally defective in peripheral BCAA metabolism reduces circulating BCAA levels by 30% (fasting)-50% (fed state). These results demonstrate for the first time the capacity of adipose tissue to catabolize circulating BCAAs in vivo and that coordinate regulation of adipose-tissue BCAA enzymes may modulate circulating BCAA levels.

  9. New paradigm for simplified combustion modeling of energetic solids: Branched chain gas reaction

    SciTech Connect

    Brewster, M.Q.; Ward, M.J.; Son, S.F.

    1997-09-01

    Two combustion models with simple but rational chemistry are compared: the classical high gas activation energy (E{sub g}/RT {much_gt} 1) Denison-Baum-Williams (DBW) model, and a new low gas activation energy (E{sub g}/RT {much_lt} 1) model recently proposed by Ward, Son, and Brewster (WSB). Both models make the same simplifying assumptions of constant properties, Lewis number unity, single-step, second order gas phase reaction, and single-step, zero order, high activation energy condensed phase decomposition. The only difference is in the gas reaction activation energy E{sub g} which is asymptotically large for DBW and vanishingly small for WSB. For realistic parameters the DBW model predicts a nearly constant temperature sensitivity {sigma}{sub p} and a pressure exponent n approaching 1. The WSB model predicts generally observed values of n = 0.7 to 0.9 and {sigma}{sub p}(T{sub o},P) with the generally observed variations with temperature (increasing) and pressure (decreasing). The WSB temperature profile also matches measured profiles better. Comparisons with experimental data are made using HMX as an illustrative example (for which WSB predictions for {sigma}{sub p}(T{sub o},P) are currently more accurate than even complex chemistry models). WSB has also shown good agreement with NC/NG double base propellant and HNF, suggesting that at the simplest level of combustion modeling, a vanishingly small gas activation energy is more realistic than an asymptotically large one. The authors conclude from this that the important (regression rate determining) gas reaction zone near the surface has more the character of chain branching than thermal decomposition.

  10. 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

  11. 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.

  12. 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.

  13. Expression of mitochondrial branched-chain aminotransferase and α-keto-acid dehydrogenase in rat brain: implications for neurotransmitter metabolism

    PubMed Central

    Cole, Jeffrey T.; Sweatt, Andrew J.; Hutson, Susan M.

    2012-01-01

    In the brain, metabolism of the essential branched chain amino acids (BCAAs) leucine, isoleucine, and valine, is regulated in part by protein synthesis requirements. Excess BCAAs are catabolized or excreted. The first step in BCAA catabolism is catalyzed by the branched chain aminotransferase (BCAT) isozymes, mitochondrial BCATm and cytosolic BCATc. A product of this reaction, glutamate, is the major excitatory neurotransmitter and precursor of the major inhibitory neurotransmitter γ-aminobutyric acid (GABA). The BCATs are thought to participate in a α-keto-acid nitrogen shuttle that provides nitrogen for synthesis of glutamate from α-ketoglutarate. The branched-chain α-keto acid dehydrogenase enzyme complex (BCKDC) catalyzes the second, irreversible step in BCAA metabolism, which is oxidative decarboxylation of the branched-chain α-keto acid (BCKA) products of the BCAT reaction. Maple Syrup Urine Disease (MSUD) results from genetic defects in BCKDC, which leads to accumulation of toxic levels of BCAAs and BCKAs that result in brain swelling. Immunolocalization of BCATm and BCKDC in rats revealed that BCATm is present in astrocytes in white matter and in neuropil, while BCKDC is expressed only in neurons. BCATm appears uniformly distributed in astrocyte cell bodies throughout the brain. The segregation of BCATm to astrocytes and BCKDC to neurons provides further support for the existence of a BCAA-dependent glial-neuronal nitrogen shuttle since the data show that BCKAs produced by glial BCATm must be exported to neurons. Additionally, the neuronal localization of BCKDC suggests that MSUD is a neuronal defect involving insufficient oxidation of BCKAs, with secondary effects extending beyond the neuron. PMID:22654736

  14. Inhibition of branched-chain alpha-ketoacid dehydrogenase kinase by thiamine pyrophosphate at different potassium ionic levels.

    PubMed

    Akita, Keiichi; Fujimura, Yukihiro; Bajotto, Gustavo; Shimomura, Yoshiharu

    2009-05-01

    Inhibition of branched-chain alpha-ketoacid dehydrogenase kinase (BDK) by thiamine pyrophosphate (TPP) was analyzed at two potassium ion (K(+)) concentrations. IC(50) values of 4.6 and 8.0 microM and inhibition constant values of 3.2 and 16.4 microM were obtained in the presence of 20 and 100 mM K(+), respectively. These results suggest that BDK is less sensitive to TPP inhibition under physiological TPP and K(+) concentrations.

  15. 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

  16. 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

  17. Circulating Branched-chain Amino Acid Concentrations Are Associated with Obesity and Future Insulin Resistance in Children and Adolescents

    PubMed Central

    McCormack, Shana E.; Shaham, Oded; McCarthy, Meaghan A.; Deik, Amy A.; Wang, Thomas J.; Gerszten, Robert E.; Clish, Clary B.; Mootha, Vamsi K.; Grinspoon, Steven K.; Fleischman, Amy

    2012-01-01

    Background Branched-chain amino acid (BCAA) concentrations are elevated in response to overnutrition, and can affect both insulin sensitivity and secretion. Alterations in their metabolism may therefore play a role in the early pathogenesis of type 2 diabetes in overweight children. Objective To determine whether pediatric obesity is associated with elevations in fasting circulating concentrations of branched-chain amino acids (isoleucine, leucine, and valine), and whether these elevations predict future insulin resistance. Research Design and Methods Sixty-nine healthy subjects, ages 8 to18 years, were enrolled as a cross-sectional cohort. A subset who were pre- or early-pubertal, ages 8 to 13 years, were enrolled in a prospective longitudinal cohort for 18 months (n=17 with complete data). Results Elevations in the concentrations of BCAA’s were significantly associated with BMI Z-score (Spearman’s Rho 0.27, p=0.03) in the cross-sectional cohort. In the subset of subjects followed longitudinally, baseline BCAA concentrations were positively associated with HOMA-IR measured 18 months later after controlling for baseline clinical factors including BMI Z-score, sex, and pubertal stage (p=0.046). Conclusions Elevations in the concentrations of circulating branched-chain amino acids are significantly associated with obesity in children and adolescents, and may independently predict future insulin resistance. PMID:22961720

  18. Clofibrate-induced reduction of plasma branched-chain amino acid concentrations impairs glucose tolerance in rats.

    PubMed

    Kadota, Yoshihiro; Kazama, Shunsuke; Bajotto, Gustavo; Kitaura, Yasuyuki; Shimomura, Yoshiharu

    2012-05-01

    It has been reported that branched-chain amino acid (BCAA) administration stimulates glucose uptake into muscles and whole body glucose oxidation in rats. The authors examined the effect of decreased plasma BCAA concentrations induced by clofibrate treatment on glucose tolerance in rats. Since clofibrate, a drug for hyperlipidemia (high serum triglyceride concentration), is a potent inhibitor of the branched-chain α-keto acid dehydrogenase kinase, clofibrate treatment (0.2 g/kg body weight) activated the hepatic branched-chain α-keto acid dehydrogenase complex, resulting in decreased plasma BCAA concentrations by 30% to 50% from the normal level. An intraperitoneal glucose tolerance test was conducted after clofibrate administration, and the results showed that peak plasma glucose concentration and the area under the curve of glucose concentration during the intraperitoneal glucose tolerance test were significantly higher in clofibrate-treated rats than in control rats. This impaired glucose tolerance in the clofibrate-treated rats was ameliorated by administration of BCAAs (0.45 g/kg body weight, leucine:isoleucine:valine = 2:1:1), which kept plasma BCAA concentrations at normal levels during the intraperitoneal glucose tolerance test. These results suggest that plasma BCAAs play an important role in maintaining normal glucose tolerance in rats.

  19. 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

  20. Stimulation of muscle ammonia production during exercise following branched-chain amino acid supplementation in humans.

    PubMed Central

    MacLean, D A; Graham, T E; Saltin, B

    1996-01-01

    1. This study examined the effects of a large (308 mg kg-1) oral dose of branched-chain amino acids (BCAAs) on muscle amino acid and ammonia (NH3) metabolism during 90 min of dynamic knee extensor exercise (64 +/- 2% of maximum workload). 2. BCAA supplementation resulted in a 4-fold increase in the arterial BCAA level (from 373 to 1537 microM, P < 0.05) and a 1.5-fold increase in the intramuscular BCAA level (from 3.4 +/- 0.2 to 5.2 +/- 0.5 mmol (kg dry weight)-1, P < 0.05) by the onset of exercise. Over the 90 min exercise period, the exercising muscle removed a total of 7104 +/- 2572 mumol kg-1 of BCAAs. In contrast, in the control trial, there was a total release of 588 +/- 86 mumol kg-1 (P < 0.05) of BCAAs. 3. The total release of NH3 over the 90 min exercise period was 2889 +/- 317 mumol kg-1 (P < 0.05) in the control trial and 4223 +/- 552 mumol kg-1 (P < 0.05) in the BCAA trial. Similarly, the total release of alanine and glutamine was 1557 +/- 153 and 2213 +/- 270 mumol kg-1, respectively, for the control trial and 2771 +/- 178 and 3476 +/- 217 mumol kg-1, respectively, for the BCAA trial. 4. The lactate release and arterial lactate values were all consistently lower in the BCAA trial than in the control trial. The net production of lactate (intramuscular shifts + total release) was lower (P < 0.05) in the BCAA trial (49.9 +/- 11.4 mmol kg-1) than in the control trial (64.0 +/- 11.7 mmol kg-1). 5. It is concluded that: (1) the administration of BCAAs can greatly increase their concentration in plasma and subsequently their uptake by muscle during exercise, and (2) long-term exercise following BCAA administration results in significantly greater muscle NH3, alanine and glutamine production, as well as lower lactate production, than is observed during exercise without BCAA supplementation. These data strongly suggest that BCAAs are an important source of NH3 during submaximal exercise and that their contribution to NH3, alanine and glutamine production can be

  1. 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.

  2. 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

  3. Amylose and amylopectin branch chain reactivity in a model derivatization system.

    PubMed

    Hong, Jung Sun; Huber, Kerry C

    2015-05-20

    The impact of starch granule structure on amylose (AM) and amylopectin (AP) chain reactivities was investigated over a 24h period in a model reaction system utilizing a fluorescent probe [DTAF, 5-(4,6-dichlorotriazinyl)aminofluorescein] as a reagent. For various reaction time intervals (0.5, 4, 12, or 24h), molecular reactivities of debranched starch derivatives were assessed via size-exclusion chromatography equipped with refractive index and fluorescence detection. For all starch chain fractions, the initial rate of derivatization (0-0.5h) was rapid, but decreased thereafter. Starch chain reactivities followed the general order: AP long chains ≫ AM, AP medium chains>AP short chains, though both AM and AP long chain reactivities were somewhat impacted by the high relative reactivity of starch chains eluting in the AM/AP long chain boundary region. Varied starch chain reactivities were attributed to their relative locale within the granule, corroborating the impact of granule architecture on molecular-level reaction patterns of starch chains.

  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. 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.

  6. Repeated sprint ability is not enhanced by caffeine, arginine, and branched-chain amino acids in moderately trained soccer players

    PubMed Central

    Ermolao, Andrea; Zanotto, Tobia; Carraro, Nicolò; Fornasier, Tommaso; Zaccaria, Marco; Neunhaeuserer, Daniel; Bergamin, Marco

    2017-01-01

    The aim was to investigate the effect of a dietary supplementation on the repeated sprint ability (RSA) performance in recreationally trained team sports athletes. Twelve young men underwent a RSA exercise protocol in five trials, in which participants ingested carbohydrates (CHO) plus caffeine (Caf), CHO plus arginine (Arg), CHO plus branched-chain amino acids (BCAA), CHO plus Caf, Arg, and BCAA (ALL), and CHO only. Heart rate, oxygen saturation, hematic lactate, ratings of perceived exertion, average sprint time, total time, best sprint time, peak power, and average power were taken. Data revealed no significant effects neither on physiological nor performance parameters with any of the supplements. PMID:28349034

  7. 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

  8. Molecular and crystalline structures of three (S)-4-alkoxycarbonyl-2-azetidinones containing long alkyl side chains from synchrotron X-ray powder diffraction data.

    PubMed

    Seijas, Luis E; Mora, Asiloé J; Delgado, Gerzon E; López-Carrasquero, Francisco; Báez, María E; Brunelli, Michela; Fitch, Andrew N

    2009-12-01

    The (S)-4-alkoxo-2-azetidinecarboxylic acids are optically active beta-lactam derivatives of aspartic acid, which are used as precursors of carbapenem-type antibiotics and poly-beta-aspartates. The crystal structures of three (S)-4-alkoxo-2-azetidinecarboxylic acids with alkyl chains with 10, 12 and 16 C atoms were solved using parallel tempering and refined against the X-ray powder diffraction data using the Rietveld method. The azetidinone rings in the three compounds display a pattern of asymmetrical bond distances and an almost planar conformation; these characteristics are compared with periodic solid-state, gas-phase density-functional theory (DFT) calculations and MOGUL average bond distances and angles from the CSD. The compounds pack along [001] as corrugated sheets separated by approximately 4.40 A and connected by hydrogen bonds of the type N-H...O.

  9. Improving Cellulose Dissolution in Ionic Liquids by Tuning the Size of the Ions: Impact of the Length of the Alkyl Chains in Tetraalkylammonium Carboxylate.

    PubMed

    Meng, Xiangqian; Devemy, Julien; Verney, Vincent; Gautier, Arnaud; Husson, Pascale; Andanson, Jean-Michel

    2017-01-30

    Twenty ionic liquids based on tetraalkylammonium cations and carboxylate anions have been synthesized, characterized, and tested for cellulose dissolution. The amount of cellulose dissolved in these ionic liquids depends strongly on the size of the ions: from 0 to 22 wt % cellulose can be dissolved at 90 °C. The best ionic liquids are less viscous and ammonium carboxylate based ionic liquids can dissolve as much as imidazolium-based ones. The viscosity of an ionic liquid can be decreased by the addition of DMSO as a cosolvent. After the addition of cosolvent, similar amounts of cellulose per ions are reached for most ionic liquids. As observed by rheology, ionic liquids with the longest alkyl chains form a gel when a high amount of cellulose is dissolved; this drastically limits their potential. Molecular simulations and IR spectroscopy have also been used with the aim of understanding how molecular interactions differ between efficient and inefficient ionic liquids.

  10. 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.

  11. 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.

  12. Oil-in-water microemulsions stabilized by 3-(N,N- dimethylalkylammonio)propanesulfonate surfactants of varying alkyl chain length: solubilisation of testos-terone propionate.

    PubMed

    Hsieh, Chien-Ming; Warisnoicharoen, Warangkana; Patel, Raju K; Kianfar, Farnoosh; Lawrence, M Jayne

    2017-03-28

    Solubilisation of the poorly-water soluble drug, testosterone propionate, in co-surfactant-free, dilutable, oil-in-water microemulsions stabilized by zwitterionic surfactants of varying alkyl chain length, namely 3-(N,N-dimethyloctylammonio)propanesulfonate and 3-(N,N-dimethyldodecylammonio)propanesulfonate and containing one of four ethyl ester oils, has been investigated. Both 3-(N,N-dimethyloctylammonio)propanesulfonate and 3-(N,N-dimethyldodecylammonio)propanesulfonate-stabilized microemulsions containing two short chain length oils, ethyl butyrate and ethyl caprylate, while only 3-(N,N-dimethyldodecylammonio)propanesulfonate formed microemulsions incorporating the longer chain length oils, ethyl palmitate and ethyl oleate, albeit to a very much reduced extent. Significantly the microemulsions containing the short chain length oils, ethyl butyrate and ethyl caprylate solubilised more testosterone propionate than the corresponding micelles. However, an inverse correlation existed between testosterone propionate solubility in the bulk oil and solubilisation in the microemulsions, in that ethyl caprylate containing microemulsions solubilised more testosterone propionate than those containing an equivalent amount of ethyl butyrate, despite the drug being more soluble in ethyl butyrate. These results suggest that drug solubility in bulk oil is a poor indicator of drug solubility in microemulsions containing that oil, and whether or not the addition of oil improves drug solubility is dependent upon on how it is incorporated within the microemulsion. The longer the chain length of the oil, the more likely the oil is to form a core in the microemulsion droplet, resulting in an additional locus of drug solubilisation and the possibility of an enhanced solubilisation capacity.

  13. 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.

  14. Branched-chain amino acid administration in surgical patients. Effects on amino acid and fuel substrate profiles.

    PubMed

    Desai, S P; Bistrian, B R; Palombo, J D; Moldawer, L L; Blackburn, G L

    1987-07-01

    During the first five days following gastric bypass surgery, 15 patients received near isotonic amino acid solutions that varied in their branched-chain amino acid (BCAA) content and amino acid profiles (15.6%, 50%, or 100% BCAA solutions). Plasma valine concentrations were elevated in patients receiving 50% and 100% BCAA solutions. Plasma alanine concentrations were highest in patients receiving 50% BCAA. Plasma free fatty acids and blood lactate concentrations were unchanged by either the operation or BCAA administration. Serum glucose concentration was unaffected by the different amino acid administrations and followed the pattern induced by stress initially and later by starvation. beta-Hydroxybutyrate concentrations increased as starvation proceeded and were highest in patients receiving the 15.6% BCAA solution. Branched-chain amino acid-enriched solutions without additional energy may be administered safely to patients recovering from operative trauma. Plasma amino acid concentrations and fuel substrate profiles appear to follow metabolic patterns determined by the physiologic response to stress and starvation and can be affected by large quantities of BCAAs.

  15. The antifungal eugenol perturbs dual aromatic and branched-chain amino acid permeases in the cytoplasmic membrane of yeast.

    PubMed

    Darvishi, Emad; Omidi, Mansoor; Bushehri, Ali Akbar Shahnejat; Golshani, Ashkan; Smith, Myron L

    2013-01-01

    Eugenol is an aromatic component of clove oil that has therapeutic potential as an antifungal drug, although its mode of action and precise cellular target(s) remain ambiguous. To address this knowledge gap, a chemical-genetic profile analysis of eugenol was done using ∼4700 haploid Saccharomyces cerevisiae gene deletion mutants to reveal 21 deletion mutants with the greatest degree of susceptibility. Cellular roles of deleted genes in the most susceptible mutants indicate that the main targets for eugenol include pathways involved in biosynthesis and transport of aromatic and branched-chain amino acids. Follow-up analyses showed inhibitory effects of eugenol on amino acid permeases in the yeast cytoplasmic membrane. Furthermore, phenotypic suppression analysis revealed that eugenol interferes with two permeases, Tat1p and Gap1p, which are both involved in dual transport of aromatic and branched-chain amino acids through the yeast cytoplasmic membrane. Perturbation of cytoplasmic permeases represents a novel antifungal target and may explain previous observations that exposure to eugenol results in leakage of cell contents. Eugenol exposure may also contribute to amino acid starvation and thus holds promise as an anticancer therapeutic drug. Finally, this study provides further evidence of the usefulness of the yeast Gene Deletion Array approach in uncovering the mode of action of natural health products.

  16. Peroxisome protein transportation affects metabolism of branched-chain fatty acids that critically impact growth and development of C. elegans.

    PubMed

    Wang, Rencheng; Kniazeva, Marina; Han, Min

    2013-01-01

    The impact of specific lipid molecules, including fatty acid variants, on cellular and developmental regulation is an important research subject that remains under studied. Monomethyl branched-chain fatty acids (mmBCFAs) are commonly present in multiple organisms including mammals, however our understanding of mmBCFA functions is very limited. C. elegans has been the premier model system to study the functions of mmBCFAs and their derived lipids, as mmBCFAs have been shown to play essential roles in post-embryonic development in this organism. To understand more about the metabolism of mmBCFAs in C. elegans, we performed a genetic screen for suppressors of the L1 developmental arrest phenotype caused by mmBCFA depletion. Extensive characterization of one suppressor mutation identified prx-5, which encodes an ortholog of the human receptor for the type-1 peroxisomal targeting signal protein. Our study showed that inactivating prx-5 function compromised the peroxisome protein import, resulting in an increased level of branched-chain fatty acid C17ISO in animals lacking normal mmBCFA synthesis, thereby restoring wild-type growth and development. This work reveals a novel connection between peroxisomal functions and mmBCFA metabolism.

  17. Pyruvate Decarboxylase Catalyzes Decarboxylation of Branched-Chain 2-Oxo Acids but Is Not Essential for Fusel Alcohol Production by Saccharomyces cerevisiae

    PubMed Central

    ter Schure, Eelko G.; Flikweert, Marcel T.; van Dijken, Johannes P.; Pronk, Jack T.; Verrips, C. Theo

    1998-01-01

    The fusel alcohols 3-methyl-1-butanol, 2-methyl-1-butanol, and 2-methyl-propanol are important flavor compounds in yeast-derived food products and beverages. The formation of these compounds from branched-chain amino acids is generally assumed to occur via the Ehrlich pathway, which involves the concerted action of a branched-chain transaminase, a decarboxylase, and an alcohol dehydrogenase. Partially purified preparations of pyruvate decarboxylase (EC 4.1.1.1) have been reported to catalyze the decarboxylation of the branched-chain 2-oxo acids formed upon transamination of leucine, isoleucine, and valine. Indeed, in a coupled enzymatic assay with horse liver alcohol dehydrogenase, cell extracts of a wild-type Saccharomyces cerevisiae strain exhibited significant decarboxylation rates with these branched-chain 2-oxo acids. Decarboxylation of branched-chain 2-oxo acids was not detectable in cell extracts of an isogenic strain in which all three PDC genes had been disrupted. Experiments with cell extracts from S. cerevisiae mutants expressing a single PDC gene demonstrated that both PDC1- and PDC5-encoded isoenzymes can decarboxylate branched-chain 2-oxo acids. To investigate whether pyruvate decarboxylase is essential for fusel alcohol production by whole cells, wild-type S. cerevisiae and an isogenic pyruvate decarboxylase-negative strain were grown on ethanol with a mixture of leucine, isoleucine, and valine as the nitrogen source. Surprisingly, the three corresponding fusel alcohols were produced in both strains. This result proves that decarboxylation of branched-chain 2-oxo acids via pyruvate decarboxylase is not an essential step in fusel alcohol production. PMID:9546164

  18. Separation of short-chain branched polyolefins by high-temperature gradient adsorption liquid chromatography.

    PubMed

    Macko, Tibor; Brüll, Robert; Alamo, Rufina G; Stadler, Florian J; Losio, Simone

    2011-02-01

    A new separation principle was recently introduced into the analytical characterization of polyolefins by researchers from the German Institute for Polymers in Darmstadt. It was demonstrated that polyolefins can be selectively separated via high-performance liquid chromatography on the basis of their adsorption/desorption behaviours at temperatures as high as 160 °C. A Hypercarb® column packed with porous graphite gave the best results. The mobile phase consisted of a mixture of 1-decanol and 1,2,4-trichlorobenzene. In this work, the same chromatographic system is applied to the separation of ethylene/alkene and ethylene/norbornene copolymers. It was found that the elution volumes of the samples correlate linearly with the average chemical composition of samples. The elution volume is indirectly proportional to the concentration of branches in the ethylene/alkene copolymer. Branching shortens the length of continuous methylene sequences of the polymer backbone, thus decreasing the probability of orientation of a methylene sequence in a flat conformation on the graphite surface, which enables the most intensive van der Waals interactions between the methylene backbone and the carbon surface. An opposite trend in the elution order has been found for ethylene/norbornene copolymers. The elution volume of the ethylene/norbornene copolymers increased with the concentration of norbornene. It indicates pronounced attractive interactions between graphite and the cyclic comonomer.

  19. Affinity alkylation of the active site of C21 steroid side-chain cleavage cytochrome P-450 from neonatal porcine testis: a unique cysteine residue alkylated by 17-(bromoacetoxy)progesterone.

    PubMed

    Onoda, M; Haniu, M; Yanagibashi, K; Sweet, F; Shively, J E; Hall, P F

    1987-01-27

    The affinity alkylating progesterone analogue 17-(bromoacetoxy)progesterone has been used to label the active site of a microsomal cytochrome P-450 enzyme from neonatal pig testis. The enzyme causes removal of the C20 and C21 side chains from the substrates progesterone and pregnenolone by catalyzing both 17-hydroxylase and C17,20-lyase reactions, which produce the corresponding C19 steroidal precursors of testosterone. The progesterone analogue causes simultaneous inactivation of the two catalytic activities of the enzyme by a first-order kinetic process that obeys saturation kinetics. Progesterone and 17-hydroxyprogesterone each protect the enzyme against inactivation. The progesterone and analogue is a competitive inhibitor of the enzyme with Ki values of 8.4 microM and 7.8 microM for progesterone and 17-hydroxyprogesterone, respectively. The enzyme inactivation and kinetic data are consistent with a theory proposing that the analogue and the two substrates compete for the same active site. The radioactive analogue 17-[( 14C]bromoacetoxy)progesterone causes inactivation of the enzyme with incorporation of 1.5-2.2 mol of the analogue per mole of inactivated enzyme. When this experiment is carried out in the presence of a substrate, then 0.9-1.2 mol of radioactive analogue is incorporated per mole of inactivated enzyme. The data suggest that the analogue can bind to two different sites, one of which is related to the catalytic site. Radiolabeled enzyme samples, from reactions of the 14C-labeled analogue with the enzyme alone or with enzyme in the presence of a substrate, were subjected to amino acid analysis and also to tryptic digestion and peptide mapping.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Affinity alkylation of the active site of C/sub 21/ steroid side-chain cleavage cytochrome P-450 from neonatal porcine testis: a unique cysteine residue alkylated by 17-(bromoacetoxy)progesterone

    SciTech Connect

    Onoda, M.; Haniu, M.; Yanagibashi, K.; Sweet, F.; Shively, J.E.; Hall, P.F.

    1987-01-27

    The affinity alkylating progesterone analogue 17-(bromoacetoxy)progesterone has been used to label the active site of a microsomal cytochrome P-450 enzyme from neonatal pig testis. The enzyme causes removal of the C/sub 20/ and C/sub 21/ side chains from the substrates progesterone and pregnenolone by catalyzing both 17-hydroxylase and C/sub 17,20/-lyase reactions, which produce the corresponding C/sub 1//sup 9/ steroidal precursors of testosterone. The progesterone analogue causes simultaneous inactivation of the two catalytic activities of the enzyme by a first-order kinetic process that obeys saturation kinetics. Progesterone and 17-hydroxyprogesterone each protect the enzyme against inactivation. The progesterone analogue is a competitive inhibitor of the enzyme with K/sub i/ values of 8.4 ..mu..M and 7.8 ..mu..M for progesterone and 17-hydroxyprogesterone, respectively. The enzyme inactivation and kinetic data are consistent with a theory proposing that the analogue and the two substrates compete for the same active site. The radioactive analogue 17-((/sup 14/C)bromoacetoxy)progesterone causes inactivation of the enzyme with incorporation of 1.5-2.2 mol of the analogue per mole of inactivated enzyme. When this experiment is carried out in the presence of a substrate, then 0.9-1.2 mol of radioactive analogue is incorporated per mole of inactivated enzyme. The data suggest that the analogue can bind to two different sites, one of which is related to the catalytic site. Radiolabeled enzyme samples, from reactions of the /sup 14/C-labeled analogue with the enzyme alone or with enzyme in the presence of a substrate, were subjected to amino acid analysis and also in tryptic digestion and peptide mapping.

  1. Characterization of a novel debranching enzyme from Nostoc punctiforme possessing a high specificity for long branched chains

    SciTech Connect

    Choi, Ji-Hye; Lee, Heeseob; Kim, Young-Wan; Park, Jong-Tae; Woo, Eui-Jeon; Kim, Myo-Jeong; Lee, Byong-Hoon

    2009-01-09

    A novel debranching enzyme from Nostoc punctiforme PCC73102 (NPDE) exhibits hydrolysis activity toward both {alpha}-(1,6)- and {alpha}-(1,4)-glucosidic linkages. The action patterns of NPDE revealed that branched chains are released first, and the resulting maltooligosaccharides are then hydrolyzed. Analysis of the reaction with maltooligosaccharide substrates labeled with {sup 14}C-glucose at the reducing end shows that NPDE specifically liberates glucose from the reducing end. Kinetic analyses showed that the hydrolytic activity of NPDE is greatly affected by the length of the substrate. The catalytic efficiency of NPDE increased considerably upon using substrates that can occupy at least eight glycone subsites such as maltononaose and maltooctaosyl-{alpha}-(1,6)-{beta}-cyclodextrin. These results imply that NPDE has a unique subsite structure consisting of -8 to +1 subsites. Given its unique subsite structure, side chains shorter than maltooctaose in amylopectin were resistant to hydrolysis by NPDE, and the population of longer side chains was reduced.

  2. Cross-talk between branched-chain amino acids and hepatic mitochondria is compromised in nonalcoholic fatty liver disease

    PubMed Central

    Kalavalapalli, Srilaxmi; Bril, Fernando; Garrett, Timothy J.; Nautiyal, Manisha; Mathew, Justin T.; Williams, Caroline M.; Cusi, Kenneth

    2015-01-01

    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

  3. 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.

  4. 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

  5. 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 .

  6. The ability of single-chain surfactants to emulsify an aqueous-based liquid crystal oscillates with odd-even parity of alkyl-chain length.

    PubMed

    Varghese, Nisha; Shetye, Gauri S; Yang, Sijie; Wilkens, Stephan; Smith, Robert P; Luk, Yan-Yeung

    2013-12-15

    The physical properties of many organic molecules often oscillate when the number of carbons in their aliphatic chains changes from odd to even. This odd-even effect for single-chain surfactants in solution is rarely observed. Here, we report the ability of single-chain surfactants to emulsify a class of non-amphiphilic organic salts, disodium cromoglycate (5'DSCG) oscillates as a function of the odd or even number of the aliphatic carbons. This system provides a water-in-oil-in-water emulsion, in which aqueous droplets of 5'DSCG in liquid crystal phases are coated with single-chain surfactants in a bulk carrying aqueous solution. For both surfactants of [Formula: see text] and CH3(CH2)nCOO(-)Na(+), the ability to emulsify 5'DSCG molecules in water is stronger for surfactants with an odd number of sp(3)-hybridized carbon atoms in the aliphatic chains than those with an even number. This observed odd-even effect is consistent with the notion that conventional micelles possess a core of randomly arranged surfactant hydrocarbon tails. However, this water-in-oil-in-water resembles a vesicle system in which the surfactants assemble in a highly ordered structure that separates two aqueous systems. These new self-assembled phases have potential application in the formulation and design of new organic soft materials.

  7. Tissue-of-origin Dictates Branched-Chain Amino Acid Metabolism in Mutant Kras-driven Cancers

    PubMed Central

    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.

    2017-01-01

    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 utilize branched-chain amino acids (BCAAs) differently. NSCLC tumors incorporate free BCAAs into tissue protein and use BCAAs as a nitrogen source while 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 utilization, 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

  8. Elevation of branched-chain amino acid levels in diabetes and NAFL and changes with antidiabetic drug treatment.

    PubMed

    Iwasa, Motoh; Ishihara, Tomoaki; Mifuji-Moroka, Rumi; Fujita, Naoki; Kobayashi, Yoshinao; Hasegawa, Hiroshi; Iwata, Kazuko; Kaito, Masahiko; Takei, Yoshiyuki

    2015-01-01

    Diabetes mellitus (DM), non-alcoholic fatty liver (NAFL), and obesity are associated with elevated branched-chain amino acid (BCAA) levels, but the mechanism and significance of this has not been elucidated. Eighty-four subjects were enrolled including 43 with DM. Serum BCAA levels were positively correlated with waist-hip ratio and ALT. Serum BCAA levels in subjects with DM were higher than non-DM and those in subjects with NAFL were also higher than non-NAFL. Treatment with pioglitazone and alogliptin (19 of 43 DM subjects) improved serum haemoglobin A1c and decreased BCAA levels. The decrease in BCAAs with improved glucose metabolism suggests that abnormal glucose metabolism is also a factor in elevated BCAA levels.

  9. Color identification and fuzzy reasoning based monitoring and controlling of fermentation process of branched chain amino acid

    NASA Astrophysics Data System (ADS)

    Ma, Lei; Wang, Yizhong; Xu, Qingyang; Huang, Huafang; Zhang, Rui; Chen, Ning

    2009-11-01

    The main production method of branched chain amino acid (BCAA) is microbial fermentation. In this paper, to monitor and to control the fermentation process of BCAA, especially its logarithmic phase, parameters such as the color of fermentation broth, culture temperature, pH, revolution, dissolved oxygen, airflow rate, pressure, optical density, and residual glucose, are measured and/or controlled and/or adjusted. The color of fermentation broth is measured using the HIS color model and a BP neural network. The network's input is the histograms of hue H and saturation S, and output is the color description. Fermentation process parameters are adjusted using fuzzy reasoning, which is performed by inference rules. According to the practical situation of BCAA fermentation process, all parameters are divided into four grades, and different fuzzy rules are established.

  10. [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.

  11. Role of Chain Microstructure and Branching on Solution and Thin Film Phase Behavior

    DTIC Science & Technology

    2015-11-30

    isoprene-g-styrene) of High Molecular Weight by a Combination of Anionic Polymerization and Free Radical Emulsion Polymerization , Polymer Chemistry...impacts  applications  that require high‐performance  polymers  that have properties found in rigid and semiflexible  chains, such as high glass transition...microscopy.  Imaging  polymeric  structures formed in  organic  solution is a well‐known challenge because solvent volatility makes  preparation of

  12. 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.

  13. Regulation of hepatic branched-chain α-ketoacid dehydrogenase complex in rats fed a high-fat diet.

    PubMed

    Kadota, Yoshihiro; Toyoda, Takanari; Kitaura, Yasuyuki; Adams, Sean H; Shimomura, Yoshiharu

    2013-12-01

    Branched-chain α-ketoacid (BCKA) dehydrogenase complex (BCKDC) regulates branched-chain amino acid (BCAA) metabolism at the level of BCKA catabolism. It has been demonstrated that the activity of hepatic BCKDC is markedly decreased in type 2 diabetic animal models. In this study, we examined the regulation of hepatic BCKDC in rats with diet-induced obesity (DIO). Rats were fed a control or a 60% of energy high-fat diet (HFD) for twelve weeks. Concentrations of blood components and the activities and protein amounts of hepatic BCKDC and its specific kinase (BDK) were measured. The concentrations of plasma glucose, insulin, and corticosterone were significantly elevated in DIO rats compared to those fed the control diet, suggestive of insulin resistance. Blood BCAA concentrations were not increased. The activity of hepatic BCKDC that was present in the active form in the liver was higher in DIO rats compared to controls, although the total activity and the enzyme amount were not different between two diet groups. The activity of hepatic BDK and the abundance of BDK bound to the BCKDC were decreased in DIO rats. The total amount of hepatic BDK was also significantly decreased in DIO rats. In rats made obese through HFD feeding, in contrast to prior studies in rat models of type 2 diabetes, hepatic BDK was down-regulated and thereby hepatic BCKDC was activated, suggesting that DIO promotes liver BCKA catabolism. In this model there was no evidence that increased blood BCAAs drive DIO-associated insulin resistance, since concentrations of BCAAs were not altered by DIO.

  14. Starch with a slow digestion property produced by altering its chain length, branch density, and crystalline structure.

    PubMed

    Ao, Zihua; Simsek, Senay; Zhang, Genyi; Venkatachalam, Mahesh; Reuhs, Bradley L; Hamaker, Bruce R

    2007-05-30

    The hypothesis of increasing the branch density of starch to reduce its digestion rate through partial shortening of amylopectin exterior chains and the length of amylose was investigated. Starch products prepared using beta-amylase, beta-amylase and transglucosidase, maltogenic alpha-amylase, and maltogenic alpha-amylase and transglucosidase showed significant reduction of rapidly digested starch by 14.5%, 29.0%, 19.8%, and 31.0% with a concomitant increase of slowly digested starch by 9.0%, 19.7%, 5.7%, and 11.0%, respectively. The resistant starch content increased from 5.1% to 13.5% in treated starches. The total contents of the prebiotics isomaltose, isomaltotriose, and panose (Isomaltooligosaccharides) were 2.3% and 5.5%, respectively, for beta-amylase/transglucosidase- and maltogenic alpha-amylase/transglucosidase-treated starches. The molecular weight distribution of enzyme-treated starches and their debranched chain length distributions, analyzed using high-performance size-exclusion chromatography with multiangle laser light scattering and refractive index detection (HPSEC-MALLS-RI) and HPSEC-RI, showed distinctly different patterns among starches with different enzyme treatments. A larger proportion of low molecular weight fractions appeared in starches treated additionally with transglucosidase. All enzyme-treated starches showed a mixture of B- and V-type X-ray diffraction patterns, and 1H NMR spectra showed a significant increase of alpha-1,6 linkages. Both the increase of the starch branch density and the crystalline structure in the treated starches likely contribute to their slow digestion property.

  15. YjeH Is a Novel Exporter of l-Methionine and Branched-Chain Amino Acids in Escherichia coli

    PubMed Central

    Liu, Qian; Liang, Yong; Zhang, Yun; Shang, Xiuling; Liu, Shuwen; Wen, Jifu

    2015-01-01

    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. PMID:26319875

  16. 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

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzenamine, N-phenyl-, ar arâ²-(C9... Significant New Uses for Specific Chemical Substances § 721.10023 Benzenamine, N-phenyl-, ar ar′-(C9-rich C88...) 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

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzenamine, N-phenyl-, ar arâ²-(C9... Significant New Uses for Specific Chemical Substances § 721.10023 Benzenamine, N-phenyl-, ar ar′-(C9-rich C8...) 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

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzenamine, N-phenyl-, ar arâ²-(C9... Significant New Uses for Specific Chemical Substances § 721.10023 Benzenamine, N-phenyl-, ar ar′-(C9-rich C8...) The chemical substance identified as benzenamine, N-phenyl-, ar,ar′-(C9-rich C8-10-branched...

  19. 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

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Benzenamine, N-phenyl-, ar arâ²-(C9... Significant New Uses for Specific Chemical Substances § 721.10023 Benzenamine, N-phenyl-, ar ar′-(C9-rich C88...) The chemical substance identified as benzenamine, N-phenyl-, ar,ar′-(C9-rich C8-10-branched...

  20. 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

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzenamine, N-phenyl-, ar arâ²-(C9... Significant New Uses for Specific Chemical Substances § 721.10023 Benzenamine, N-phenyl-, ar ar′-(C9-rich C8...) The chemical substance identified as benzenamine, N-phenyl-, ar,ar′-(C9-rich C8-10-branched...

  1. 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

  2. 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

  3. Chromatographic behaviour of naproxen-cyclodextrin complexes stationary phase C8 alkyl chain as competitor for the drug release from cyclodextrin cavity.

    PubMed

    Rozou, S; Antoniadou-Vyza, E

    2004-07-02

    Cyclodextrins are known to alter the absorptivity of the guest molecules, therefore, analytical methods that are based on the spectrophotometric data present accuracy problems. In this work, using RP-HPLC methods for naproxen-cyclodextrins quantitation, extensive analytical inaccuracies are detected. Competitive complexation technique is utilised in an attempt to develop an analytical method enabling the determination of naproxen as a free drug. For this reason, stationary phases with silica ligands that can function as competing agents were used, thus contributing to the drug release. The release of the drug from cyclodextrins complexes is achieved by modification of the thermodynamic parameters that determine the stability constant, by changing: the interactions with the mobile phase components (e.g. pH, organic modifier, competitive agents) and the interactions with the stationary phase ligands (C8). After studying the parameters affecting the interaction between the alkyl-chain C8 and naproxen:cyclodextrin complexes, we developed and validated a new specific method for the accurate determination of the drug. Consecutive accumulation of the cyclodextrins molecules on the stationary phase was studied.

  4. 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.

  5. Evaluation and comparison of n-alkyl chain and polar ligand bonded stationary phases for protein separation in reversed-phase liquid chromatography.

    PubMed

    Ding, Ling; Guo, Zhimou; Xiao, Yuansheng; Xue, Xingya; Zhang, Xiuli; Liang, Xinmiao

    2014-09-01

    Protein retention is very sensitive to the change of solvent composition in reversed-phase liquid chromatography for so called "on-off" mechanism, leading to difficulty in mobile phase optimization. In this study, a novel 3-chloropropyl trichlorosilane ligand bonded column was prepared for protein separation. The differences in retention characteristics between the 3-chloropropyl trichlorosilane ligand bonded column and n-alkyl chain modified (C2, C4, C8) stationary phases were elucidated by the retention equation l nk=a+cC(B). Retention parameters (a and c) of nine standard proteins with different molecular weights were calculated by using homemade software. Results showed that retention times of nine proteins were similar on four columns, but the 3-chloropropyl trichlorosilane ligand bonded column obtained the lowest retention parameter values of larger proteins. It meant that their retention behavior affected by acetonitrile concentration would be different due to lower |c| values. More specifically, protein elution windows were broader, and retentions were less sensitive to the change of acetonitrile concentration on the 3-chloropropyl trichlorosilane ligand bonded column than that on other columns. Meanwhile, the 3-chloropropyl trichlorosilane ligand bonded column displayed distinctive selectivity for some proteins. Our results indicated that stationary phase with polar ligand provided potential solutions to the "on-off" problem and optimization in protein separation.

  6. From chain collapse to new structures: spectroscopic properties of poly(3-thiophene acetic acid) upon binding by alkyl trimethylammonium bromide surfactants.

    PubMed

    Franco, I Echavarri; Lorchat, P; Lamps, J-P; Schmutz, M; Schröder, A; Catala, J-M; Combet, J; Schosseler, F

    2012-03-13

    The binding of cationic surfactants with varying alkyl chain length to a regiorandom conjugated polyanion, poly(3-thiophene acetic acid) (PTAA), is studied in an aqueous buffer by using absorption and emission spectroscopies, photon correlation spectroscopy, isothermal titration calorimetry, and cryogenic transmission electron microscopy. We study the mixed solutions as a function of composition ratio R of surfactant molecules to monomer units molar concentrations, at low polymer concentration and in a very wide composition range (10(-6) < R < 10(2)) below the critical micellar concentration. Upon surfactant binding, the molecularly dispersed chains first collapse progressively and then form new structures as the mixed aggregates get enriched in surfactant. The collapse leads to a strong decrease of the conjugation length and to a blue shift of the absorption spectra by 30 to 50 nm. The new structures are responsible for a new intense emission band at about 600 nm, red-shifted by nearly 130 nm from the initial emission maximum of the polymer (~472 nm). As the surfactant tail becomes shorter, the blue shift of the absorption spectra and the intensity raise of the new emission are delayed to larger composition ratios while their variations become smoother functions of the surfactant concentration. These particular spectroscopic properties of PTAA seem related to its unique combination of a strongly hydrophobic backbone, a large ratio of contour length to persistence length, and an overall good aqueous solubility. Our results show that such features are well suited to design a colorimetric biosensor at small composition ratio, and a fluorescent biomarker at large composition ratio.

  7. 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.

  8. 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.

  9. 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...

  10. Additional oxidized and alkyl chain breakdown metabolites of the plasticizer DINCH in urine after oral dosage to human volunteers.

    PubMed

    Schütze, André; Otter, Rainer; Modick, Hendrik; Langsch, Angelika; Brüning, Thomas; Koch, Holger M

    2017-01-01

    Hexamoll(®) DINCH(®) (diisononyl-cyclohexane-1,2-dicarboxylate) is a new high molecular weight plasticizer and a non-aromatic phthalate substitute. In this follow-up study, we further investigated the extensive oxidative metabolism of Hexamoll(®) DINCH(®) after oral dosage of 50 mg to three male volunteers (0.552-0.606 mg/kg body weight). Urine samples were consecutively collected over 48 h post-dose. Chemical analysis was carried out by HPLC-MS/MS with labeled internal standards. New metabolites were tentatively identified and quantified via fragmentation analogies and new standard substances. In addition to the five urinary DINCH metabolites previously reported by us, we identified two groups of extensively oxidized metabolites characterized (a) by multiple side chain oxidation and breakdown and (b) by hydroxylation at the cyclohexane ring. The five newly identified carboxylated breakdown metabolites represented in sum 5.12 ± 0.49 % of the applied dose. MCHxCH (cyclohexane-1,2-dicarboxylic acid mono carboxyhexyl ester) was identified as a major metabolite (2.71 ± 0.34 %) and thus represents the second most important specific metabolite of DINCH after OH-MINCH (10.7 ± 2.1 %). Less than 1 % was excreted as ring-hydroxylated metabolites (four metabolites identified). Based upon a new reference standard, we can also update oxo-MINCH to 2.6 % of the applied dose. This follow-up study increases the total amount of the recovered dose from 39.2 to 45.7 % and describes a new major metabolite (MCHxCH) of DINCH that can be used as an additional valuable and specific biomarker to assess DINCH(®) exposure in future human biomonitoring studies.

  11. Simvastatin increases liver branched-chain α-ketoacid dehydrogenase activity in rats fed with low protein diet.

    PubMed

    Knapik-Czajka, Malgorzata

    2014-11-05

    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

  12. Effects of oral branched-chain amino acids on hepatic encephalopathy and outcome in patients with liver cirrhosis.

    PubMed

    Kawaguchi, Takumi; Taniguchi, Eitaro; Sata, Michio

    2013-10-01

    Branched-chain amino acids (BCAAs) constituting of valine, leucine, and isoleucine act as both substrates of proteins and as key regulators for various nutrient metabolisms. Patients with liver cirrhosis frequently lack sufficient BCAAs and therefore suffer from various metabolic disorders. Hepatic encephalopathy (HE) is a severe metabolic disorder with neurologic manifestations such as flapping tremors and coma in patients with liver cirrhosis. In addition, a mild form of HE known as minimal HE (MHE) is an important social issue because it occurs in up to 80% of patients with chronic liver disease and affects prognosis and activities of daily living, possibly resulting in falls and motor vehicle accidents. Although HE/MHE can be caused by various pathological conditions, including in an accumulation of mercaptans, short-chain fatty acids, and alterations in the gut flora, hyperammonemia has also been implicated in an important pathogenesis of HE/MHE. Besides urea cycle of liver, ammonia can be detoxified in the skeletal muscles by the amidation process for glutamine synthesis using BCAAs. Thus, BCAA supplementation may enhance detoxification of ammonia in skeletal muscle and may be a possible therapeutic strategy for HE/MHE. In this review, we summarize the clinical impacts of BCAA supplementation on HE/MHE and discuss possible mechanisms for a BCAA-induced improvement of HE/MHE. Furthermore, we present some modifications of oral BCAA therapy for improvement of efficacy in HE treatment. We also briefly describe pleiotropic benefits of BCAAs on life-threatening events and overall prognosis in patients with liver cirrhosis.

  13. Identification of In-Chain-Functionalized Compounds and Methyl-Branched Alkanes in Cuticular Waxes of Triticum aestivum cv. Bethlehem

    PubMed Central

    Racovita, Radu C.; Jetter, Reinhard

    2016-01-01

    In this work, cuticular waxes from flag leaf blades and peduncles of Triticum aestivum cv. Bethlehem were investigated in search for novel wax compounds. Seven wax compound classes were detected that had previously not been reported, and their structures were elucidated using gas chromatography-mass spectrometry of various derivatives. Six of the classes were identified as series of homologs differing by two methylene units, while the seventh was a homologous series with homologs with single methylene unit differences. In the waxes of flag leaf blades, secondary alcohols (predominantly C27 and C33), primary/secondary diols (predominantly C28) and esters of primary/secondary diols (predominantly C50, combining C28 diol with C22 acid) were found, all sharing similar secondary hydroxyl group positions at and around C-12 or ω-12. 7- and 8-hydroxy-2-alkanol esters (predominantly C35), 7- and 8-oxo-2-alkanol esters (predominantly C35), and 4-alkylbutan-4-olides (predominantly C28) were found both in flag leaf and peduncle wax mixtures. Finally, a series of even- and odd-numbered alkane homologs was identified in both leaf and peduncle waxes, with an internal methyl branch preferentially on C-11 and C-13 of homologs with even total carbon number and on C-12 of odd-numbered homologs. Biosynthetic pathways are suggested for all compounds, based on common structural features and matching chain length profiles with other wheat wax compound classes. PMID:27820857

  14. Effects of squat exercise and branched-chain amino acid supplementation on plasma free amino acid concentrations in young women.

    PubMed

    Shimomura, Yoshiharu; Kobayashi, Hisamine; Mawatari, Kazunori; Akita, Keiichi; Inaguma, Asami; Watanabe, Satoko; Bajotto, Gustavo; Sato, Juichi

    2009-06-01

    The present study was conducted to examine alterations in plasma free amino acid concentrations induced by squat exercise and branched-chain amino acid (BCAA) supplementation in young, untrained female subjects. In the morning on the exercise session day, participants ingested drinks containing either BCAA (isoleucine:leucine:valine=1:2.3:1.2) or dextrin (placebo) at 0.1 g/kg body weight 15 min before a squat exercise session, which consisted of 7 sets of 20 squats, with 3 min intervals between sets. In the placebo trial, plasma BCAA concentrations were decreased subsequent to exercise, whereas they were significantly increased in the BCAA trial until 2 h after exercise. Marked changes in other free amino acids in response to squat exercise and BCAA supplementation were observed. In particular, plasma concentrations of methionine and aromatic amino acids were temporarily decreased in the BCAA trial, being significantly lower than those in the placebo trial. These results suggest that BCAA intake before exercise affects methionine and aromatic amino acid metabolism.

  15. Influence of lysolecithin and Tween 80 on the colloidal stability of branched chain amino acids in a nanosuspension system.

    PubMed

    Hong, Chi Rac; Lee, Gyu Whan; Paik, Hyun-Dong; Chang, Pahn-Shick; Choi, Seung Jun

    2017-04-15

    This study examined the influence of stabilizers on the solubility and colloidal stability of branched chain amino acids (BCAAs) nanosuspended through high pressure homogenization at 70°C. Although homogenization increased the initial BCAA solubility, irrespective of pH (pH 3 or 6), homogenization alone was not sufficient to increase their long-term solubility. The incorporation of stabilizers into nanosuspensions increased the saturation concentration of BCAAs but the effect of stabilizers on the increase in the saturation concentration of BCAAs was more pronounced at pH 6.0. At pH 6, Tween 80 dramatically increased the colloidal stability of the BCAA nanosuspensions, independent of the BCAA:stabilizer ratio but not at pH 3. However, the effect of lysolecithin on the colloidal stability of nanosuspended BCAAs varied depending on pH and BCAA:lysolecithin ratio. In lysolecithin-related nanosuspensions, there was no clear relationship between the colloidal stability and nanosuspension conditions including pH and BCAA:lysolecithin ratio. This study could provide a useful information on stabilizer selection for the development of liquid or colloidal products with improved solubility and colloidal stability of nanosuspended BCAAs.

  16. Acute dopamine depletion with branched chain amino acids decreases auditory top-down event-related potentials in healthy subjects.

    PubMed

    Neuhaus, Andres H; Goldberg, Terry E; Hassoun, Youssef; Bates, John A; Nassauer, Katharine W; Sevy, Serge; Opgen-Rhein, Carolin; Malhotra, Anil K

    2009-06-01

    Cerebral dopamine homeostasis has been implicated in a wide range of cognitive processes and is of great pathophysiological importance in schizophrenia. A novel approach to study cognitive effects of dopamine is to deplete its cerebral levels with branched chain amino acids (BCAAs) that acutely lower dopamine precursor amino acid availability. Here, we studied the effects of acute dopamine depletion on early and late attentive cortical processing. Auditory event-related potential (ERP) components N2 and P3 were investigated using high-density electroencephalography in 22 healthy male subjects after receiving BCAAs or placebo in a randomized, double-blind, placebo-controlled crossover design. Total free serum prolactin was also determined as a surrogate marker of cerebral dopamine depletion. Acute dopamine depletion increased free plasma prolactin and significantly reduced prefrontal ERP components N2 and P3. Subcomponent analysis of N2 revealed a significant attenuation of early attentive N2b over prefrontal scalp sites. As a proof of concept, these results strongly suggest that BCAAs are acting on basic information processing. Dopaminergic neurotransmission seems to be involved in auditory top-down processing as indexed by prefrontal N2 and P3 reductions during dopamine depletion. In healthy subjects, intact early cortical top-down processing can be acutely dysregulated by ingestion of BCAAs. We discuss the potential impact of these findings on schizophrenia research.

  17. Acute dopamine depletion with branched chain amino acids decreases auditory top-down event-related potentials in healthy subjects

    PubMed Central

    Neuhaus, Andres H.; Goldberg, Terry E.; Hassoun, Youssef; Bates, John A.; Nassauer, Katharine W.; Sevy, Serge; Opgen-Rhein, Carolin; Malhotra, Anil K.

    2013-01-01

    Cerebral dopamine homeostasis has been implicated in a wide range of cognitive processes and is of great pathophysiological importance in schizophrenia. A novel approach to study cognitive effects of dopamine is to deplete its cerebral levels with branched chain amino acids (BCAAs) that acutely lower dopamine precursor amino acid availability. Here, we studied the effects of acute dopamine depletion on early and late attentive cortical processing. Auditory event-related potential (ERP) components N2 and P3 were investigated using high-density electroencephalography in 22 healthy male subjects after receiving BCAAs or placebo in a randomized, double-blind, placebo-controlled crossover design. Total free serum prolactin was also determined as a surrogate marker of cerebral dopamine depletion. Acute dopamine depletion increased free plasma prolactin and significantly reduced prefrontal ERP components N2 and P3. Subcomponent analysis of N2 revealed a significant attenuation of early attentive N2b over prefrontal scalp sites. As a proof of concept, these results strongly suggest that BCAAs are acting on basic information processing. Dopaminergic neurotransmission seems to be involved in auditory top-down processing as indexed by prefrontal N2 and P3 reductions during dopamine depletion. In healthy subjects, intact early cortical top-down processing can be acutely dysregulated by ingestion of BCAAs. We discuss the potential impact of these findings on schizophrenia research. PMID:19356906

  18. 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.

  19. Branched-Chain Amino Acids as Predictors for Individual Differences of Cisplatin Nephrotoxicity in Rats: A Pharmacometabonomics Study.

    PubMed

    Zhang, Pei; Li, Wei; Chen, Jiaqing; Li, Ruiting; Zhang, Zunjian; Huang, Yin; Xu, Fengguo

    2017-03-17

    Nephrotoxicity is the dose-limiting adverse effect of cisplatin with large individual differences. Up to now, little has been done on how to recognize and predict the individual differences in either preclinical or clinical research. In the present study, important postdose indicators were screened out first and integrated into a grouping factor, according to which rats were recognized as lowly or highly sensitive individuals. Then, mass-spectrometry-based untargeted metabolomics approach was performed to dissect the metabolic differences in predose serum of the two groups. Eventually, branched-chain amino acids (BCAAs) were found to be most significant with the lowest p value of Mann-Whitney U test and the highest area under receiving operating characteristic curve (AUC-ROC). The findings were further confirmed by absolute quantitation of BCAAs using liquid chromatography-tandem mass spectrometry. Binary logistic regression showed that in the discovery set absolute BCAA contents in rat predose serum could predict cisplatin nephrotoxicity with accuracy of 85%. This result was validated by another two independent external validation sets with accuracy of 81.8 and 78.8%, respectively. This study could provide new insight into cisplatin nephrotoxicity and may help expedite personalized medicine of cisplatin or other antitumor drugs in future clinical studies.

  20. Increased plasma ammonia may inhibit cellular release of branched-chain amino acids in systemic portal encephalopathy.

    PubMed

    Jahn, H A; Schohn, D C; Koehl, C; Schmitt, R L

    1983-12-01

    Plasma amino acid patterns were determined before and after hemofiltration (HF) and hemodialysis (HD) in 6 patients with portal systemic encephalopathy (PSE) and compared with the plasma AA patterns of 16 patients with chronic renal failure (CRF) treated either by HF or HD. The branched-chain amino acids (BCAA) increased paradoxically in PSE patients during HF but not with HD. There were no differences in BCAA's with HF as compared to HD in the CRF patients. The amount of amino acids lost was the same with both treatment modalities and in both patient groups. Much of the amino acids lost were released from the intracellular space. The BCAA release was significantly higher in PSE patients during HF. No correlation was found between plasma insulin, glucagon, and cortisol levels and BCAA release. An inverse correlation was found between the amount of BCAA's released from the intracellular space and the plasma ammonia levels. It is suggested that a selective cellular transport mechanism for BCAA exists which is inhibited by high plasma ammonia levels in PSE.

  1. 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.

  2. Branched-chain amino acid-rich diet improves skeletal muscle wasting caused by cigarette smoke in rats.

    PubMed

    Tomoda, Koichi; Kubo, Kaoru; Hino, Kazuo; Kondoh, Yasunori; Nishii, Yasue; Koyama, Noriko; Yamamoto, Yoshifumi; Yoshikawa, Masanori; Kimura, Hiroshi

    2014-04-01

    Cigarette smoke induces skeletal muscle wasting by a mechanism not yet fully elucidated. Branched-chain amino acids (BCAA) in the skeletal muscles are useful energy sources during exercise or systemic stresses. We investigated the relationship between skeletal muscle wasting caused by cigarette smoke and changes in BCAA levels in the plasma and skeletal muscles of rats. Furthermore, the effects of BCAA-rich diet on muscle wasting caused by cigarette smoke were also investigated. Wistar Kyoto (WKY) rats that were fed with a control or a BCAA-rich diet were exposed to cigarette smoke for four weeks. After the exposure, the skeletal muscle weight and BCAA levels in plasma and the skeletal muscles were measured. Cigarette smoke significantly decreased the skeletal muscle weight and BCAA levels in both plasma and skeletal muscles, while a BCAA-rich diet increased the skeletal muscle weight and BCAA levels in both plasma and skeletal muscles that had decreased by cigarette smoke exposure. In conclusion, skeletal muscle wasting caused by cigarette smoke was related to the decrease of BCAA levels in the skeletal muscles, while a BCAA-rich diet may improve cases of cigarette smoke-induced skeletal muscle wasting.

  3. Is administrating branched-chain amino acid-enriched nutrition achieved symptom-free in malnourished cirrhotic patients?

    PubMed

    Tsuda, Yasuhiro; Fukui, Hideo; Sujishi, Tetsuya; Ohama, Hideko; Tsuchimoto, Yusuke; Asai, Akira; Fukunisi, Shinya; Higuchi, Kazuhide

    2014-01-01

    Administration of branched-chain amino acids (BCAA) has been reported to improve liver function, quality of life (QOL). However, in some malnourished patients, serum albumin levels do not improve in response to BCAA granules. In this study, we examined the effects of BCAA-enriched enteral nutrition in patients unresponsive to BCAA granules. Thirty-two decompensated cirrhotic patients at Osaka Medical College were enrolled in this study. Since all patients showed no improvement in serum albumin levels despite 3 months of BCAA granule administration, they were administered 50 g of a flavored BCAA-enriched enteral nutrient twice daily, i.e., during the daytime and late evening. Serum albumin levels and major cirrhotic symptoms were examined 1, 3, and 5 months after treatment initiation. Serum albumin levels improved significantly 3 months after treatment initiation (3.14 ± 0.32 g/dl vs 3.5 ± 0.31 g/dl, p<0.01), and Child-Pugh scores decreased significantly (p<0.01). In the majority (53-80%) of patients, muscles cramps, fatigue, fatigability, edema, and sleep disturbance improved within 3 months after therapy initiation. Moreover, approximately 90% of the patients became symptom-free 5 months after treatment initiation. These results indicate that switching to BCAA-enriched nutrients improves QOL of cirrhotic patients unresponsive to BCAA granules.

  4. Effects of eccentric exercise on branched-chain amino acid profiles in rat serum and skeletal muscle.

    PubMed

    Qun, Z; Xinkai, Y; Jing, W

    2014-04-01

    Supplementation of branched-chain amino acid (BCAA) is often used to attenuate exercise-induced skeletal muscle damage and promote adaptation, but no definitive conclusion on the benefits of BCAA on muscle recovery after injurious exercise can be drawn. Exploration of the systematic BCAA alteration in muscular injury-repair stage per se without any BCAA supplement should provide some useful information in favour of BCAA application in muscle regeneration after injury. One bout of 90-min downhill-running exercise was performed to cause rat skeletal muscle injury. After exercise, myofibrillar BCAA concentrations showed minor changes compared with exercise before, while serum concentrations of BCAA were lower after exercise. Especially, serum leucine, isoleucine and total BCAA concentrations 2 weeks post-run were significantly lower than normal values of exercise before (p = 0.008, p = 0.041, p = 0.015). The data demonstrate that a single eccentric exercise can significantly decrease the serum BCAA concentrations, which mean high utilization of BCAA for myogenesis after injurious exercise.

  5. 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.

  6. 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.

  7. Effect of dietary soybean oil addition on the odd-numbered and branched-chain fatty acids in rabbit meat.

    PubMed

    Papadomichelakis, George; Karagiannidou, Areti; Anastasopoulos, Vasilios; Fegeros, Konstantinos

    2010-10-01

    The effect of dietary soybean oil (SO) inclusion (20g/kg) on the odd-numbered (ONFA) and branched-chain (BCFA) fatty acids (FA) of two muscles, differing in fatness (Longissimus lumborum and Biceps femoris), was studied in 24 New ZealandxCalifornian rabbits. The increased muscle fatness in Biceps femoris (P<0.001) was related to higher saturated (P<0.01) and monounsaturated (P<0.01) fatty acids. Intramuscular ONFA and BCFA contents were not affected, but their proportions were reduced (P<0.01 and P<0.001) by SO addition, suggesting a dilution effect of the dietary polyunsaturates accumulated in both muscles, except for 17:0i which decreased only in Longissimus lumborum due to significant (P<0.05) soybean oilxmuscle interaction. The higher (P<0.05) BCFA contents and the FA profile in Biceps femoris were not affected by fatness, indicating an association with other muscle properties. The present study supplies new information on ONFA and BCFA in rabbit meat.

  8. 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...

  9. Solid-state phosphorescence of trans-bis(salicylaldiminato)platinum(II) complexes bearing long alkyl chains: morphology control towards intense emission.

    PubMed

    Komiya, Naruyoshi; Itami, Nao; Naota, Takeshi

    2013-07-15

    Morphology control for intense solid-state phosphorescence of non-emissive, but potentially emissive crystals of platinum complexes and the mechanistic rationale are described. A series of trans-bis(salicylaldiminato)platinum(II) complexes bearing linear alkyl chains (1a: n=5; 1b: n=8; 1c: n=12; 1d: n=14; 1e: n=16; 1f: n=18) was synthesized and the solid-state emission properties were examined by using crystals/aggregates prepared under various precipitation conditions. Crystals of 1e, prepared using "kinetic" conditions including rapid cooling, high concentrations, and poor solvents, emit intensive yellow phosphorescence (λ(max)=545 nm) under UV irradiation at 298 K with an absolute quantum efficiency of 0.36, whereas all the crystals of 1a-1f prepared using "thermodynamic" conditions including slow cooling, low concentrations, and good solvents were either non- or less emissive with Φ(298K) values of 0.12 (1a), 0.11 (1b), 0.10 (1c), 0.07 (1d), 0.02 (1e), and 0.02 (1f) under the same measurement conditions. The amorphous solid 1e, prepared by rapid cooling and freeze-drying, was also non-emissive (Φ(298K)=0.02, 0.02). Temperature-dependent emission spectra showed that the kinetic crystals of 1e exhibit high heat-resistance towards emission decay with increasing temperature, whereas the amorphous solid 1e is entirely heat-quenchable. This is a rare example of the change from a non-emissive crystal into a highly emissive crystal by morphology control through crystal engineering. Emission spectra and powder X-ray diffraction (XRD) patterns of the emissive, kinetic crystals of 1e are clearly distinct from those of the less emissive, thermodynamic crystals of 1a-1f. Single-crystal XRD unequivocally establishes that the thermodynamic crystals of 1d have a multilayered lamellar structure supported by highly regulated, consecutive π-stacking interactions between imine moieties, whereas the kinetic crystals of 1e have a face-to-edge lamellar structure with less

  10. Effects of carbohydrate, branched-chain amino acids, and arginine in recovery period on the subsequent performance in wrestlers

    PubMed Central

    2011-01-01

    Many athletes need to participate in multiple events in a single day. The efficient post-exercise glycogen recovery may be critical for the performance in subsequent exercise. This study examined whether post-exercise carbohydrate supplementation could restore the performance in the subsequent simulated wrestling match. The effect of branched-chain amino acids and arginine on glucose disposal and performance was also investigated. Nine well-trained male wrestlers participated in 3 trials in a random order. Each trial contained 3 matches with a 1-hr rest between match 1 and 2, and a 2-hr rest between match 2 and 3. Each match contained 3 exercise periods interspersed with 1-min rests. The subjects alternated 10-s all-out sprints and 20-s rests in each exercise period. At the end of match 2, 3 different supplementations were consumed: 1.2 g/kg glucose (CHO trial), 1 g/kg glucose + 0.1 g/kg Arg + 0.1 g/kg BCAA (CHO+AA trial), or water (placebo trial). The peak and average power in the 3 matches was similar in the 3 trials. After the supplementation, CHO and CHO+AA trial showed significantly higher glucose and insulin, and lower glycerol and non-esterified fatty acid concentrations than the placebo trial. There was no significant difference in these biochemical parameters between the CHO and CHO+AA trials. Supplementation of carbohydrate with or without BCAA and arginine during the post-match period had no effect on the performance in the following simulated match in wrestlers. In addition, BCAA and arginine did not provide additional insulinemic effect. PMID:22107883

  11. Branched-chain amino acid supplementation lowers perceived exertion but does not affect performance in untrained males.

    PubMed

    Greer, Beau Kjerulf; White, Jim P; Arguello, Eric M; Haymes, Emily M

    2011-02-01

    The purpose of this study was to determine whether branched-chain amino acid (BCAA) supplementation affects aerobic performance, ratings of perceived exertion (RPE), or substrate utilization as compared with an isocaloric, carbohydrate (CHO) beverage or a noncaloric placebo (PLAC) beverage. Nine untrained males performed three 90-minute cycling bouts at 55% VO₂ peak followed by 15-minute time trials. Subjects, who were blinded to beverage selection, ingested a total of 200 kcal via the CHO or BCAA beverage before and at 60 minutes of exercise or the PLAC beverage on the same time course. RPE and metabolic measurements were taken every 15 minutes during steady-state exercise, and each of the trials was separated by 8 weeks. Plasma glucose and BCAA concentrations were measured pre- and post-exercise. A greater distance (4.6 ± 0.6 km) was traveled in the time-trial during the CHO trial than the PLAC trial (3.9 ± 0.4 km) (p < 0.05). There was no difference between the BCAA (4.4 ± 0.5 km) and PLAC trials. RPE was reduced at the 75-minute and 90-minute mark during the BCAA trial as compared with the PLAC trial. There were no significant differences found for the trial vs. time interaction in regard to respiratory exchange ratio. Thus, CHO supplementation improves performance in a loaded time-trial as compared with a PLAC beverage. BCAA supplementation, although effective at increasing blood concentrations of BCAA, did not influence aerobic performance but did attenuate RPE as compared with a PLAC beverage.

  12. Structure of the Branched-chain Amino Acid and GTP-sensing Global Regulator, CodY, from Bacillus subtilis*

    PubMed Central

    Levdikov, Vladimir M.; Blagova, Elena; Young, Vicki L.; Belitsky, Boris R.; Lebedev, Andrey; Sonenshein, Abraham L.

    2017-01-01

    CodY is a branched-chain amino acid (BCAA) and GTP sensor and a global regulator of transcription in low G + C Gram-positive bacteria. It controls the expression of over 100 genes and operons, principally by repressing during growth genes whose products are required for adaptations to nutrient limitation. However, the mechanism by which BCAA binding regulates transcriptional changes is not clear. It is known that CodY consists of a GAF (cGMP-stimulated phosphodiesterases, adenylate cyclases, FhlA) domain that binds BCAAs and a winged helix-turn-helix (wHTH) domain that binds to DNA, but the way in which these domains interact and the structural basis of the BCAA dependence of this interaction are unknown. To gain new insights, we determined the crystal structure of unliganded CodY from Bacillus subtilis revealing a 10-turn α-helix linking otherwise discrete GAF and wHTH domains. The structure of CodY in complex with isoleucine revealed a reorganized GAF domain. In both complexes CodY was tetrameric. Size exclusion chromatography with multiangle laser light scattering (SEC-MALLS) experiments showed that CodY is a dimer at concentrations found in bacterial cells. Comparison of structures of dimers of unliganded CodY and CodY-Ile derived from the tetramers showed a splaying of the wHTH domains when Ile was bound; splaying is likely to account for the increased affinity of Ile-bound CodY for DNA. Electrophoretic mobility shift and SEC-MALLS analyses of CodY binding to 19–36-bp operator fragments are consistent with isoleucine-dependent binding of two CodY dimers per duplex. The implications of these observations for effector control of CodY activity are discussed. PMID:28011634

  13. The Effect of Branched Chain Amino Acids on Skeletal Muscle Mitochondrial Function in Young and Elderly Adults

    PubMed Central

    Tatpati, Laura L.; Irving, Brian A.; Tom, Andrea; Bigelow, Maureen L.; Klaus, Katherine; Short, Kevin R.; Nair, K. Sreekumaran

    2010-01-01

    Context: A reduction in maximal mitochondrial ATP production rate (MAPR) and mitochondrial DNA (mtDNA) abundance occurs with age in association with muscle weakness and reduced endurance in elderly people. Branched chain amino acids (BCAA) have been extensively used to improve physical performance. Objective: The objective was to determine whether an 8-h infusion of BCAA enhances MAPR equally in healthy young and elderly adults. Methods: Using a crossover study design, we compared the effect BCAA vs. saline infusion in 12 young (23.0 ± 0.8 yr) and 12 elderly (70.7 ± 1.1 yr) participants matched for sex and body mass index. Skeletal muscle MAPR and mtDNA abundance were measured in muscle biopsy samples obtained before and at the end of the 8-h infusion. Results: In young participants, MAPR with the substrates glutamate plus malate (supplying electrons to complex I) and succinate plus rotenone (complex II) increased in response to BCAA infusion, relative to a decline in MAPR in response to the saline infusion. In contrast, MAPR was unaffected by BCAA infusion in the elderly participants. Moreover, mtDNA abundance was lower in the elderly compared with the young participants but was unaffected by the BCAA infusion. Insulin and C-peptide concentrations declined over time during the saline infusion, but these declines were prevented by the BCAA infusion. Conclusions: BCAA increased skeletal muscle MAPR in the young participants in comparison with saline, but this effect was not seen in the elderly participants indicating, that unlike in the young, BCAA does not increase muscle mitochondrial function in the elderly. PMID:20022987

  14. 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.

  15. 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

  16. Branched Chain Amino Acids Cause Liver Injury in Obese/Diabetic Mice by Promoting Adipocyte Lipolysis and Inhibiting Hepatic Autophagy.

    PubMed

    Zhang, Fuyang; Zhao, Shihao; Yan, Wenjun; Xia, Yunlong; Chen, Xiyao; Wang, Wei; Zhang, Jinglong; Gao, Chao; Peng, Cheng; Yan, Feng; Zhao, Huishou; Lian, Kun; Lee, Yan; Zhang, Ling; Lau, Wayne Bond; Ma, Xinliang; Tao, Ling

    2016-11-01

    The Western meat-rich diet is both high in protein and fat. Although the hazardous effect of a high fat diet (HFD) upon liver structure and function is well recognized, whether the co-presence of high protein intake contributes to, or protects against, HF-induced hepatic injury remains unclear. Increased intake of branched chain amino acids (BCAA, essential amino acids compromising 20% of total protein intake) reduces body weight. However, elevated circulating BCAA is associated with non-alcoholic fatty liver disease and injury. The mechanisms responsible for this quandary remain unknown; the role of BCAA in HF-induced liver injury is unclear. Utilizing HFD or HFD+BCAA models, we demonstrated BCAA supplementation attenuated HFD-induced weight gain, decreased fat mass, activated mammalian target of rapamycin (mTOR), inhibited hepatic lipogenic enzymes, and reduced hepatic triglyceride content. However, BCAA caused significant hepatic damage in HFD mice, evidenced by exacerbated hepatic oxidative stress, increased hepatic apoptosis, and elevated circulation hepatic enzymes. Compared to solely HFD-fed animals, plasma levels of free fatty acids (FFA) in the HFD+BCAA group are significantly further increased, due largely to AMPKα2-mediated adipocyte lipolysis. Lipolysis inhibition normalized plasma FFA levels, and improved insulin sensitivity. Surprisingly, blocking lipolysis failed to abolish BCAA-induced liver injury. Mechanistically, hepatic mTOR activation by BCAA inhibited lipid-induced hepatic autophagy, increased hepatic apoptosis, blocked hepatic FFA/triglyceride conversion, and increased hepatocyte susceptibility to FFA-mediated lipotoxicity. These data demonstrated that BCAA reduces HFD-induced body weight, at the expense of abnormal lipolysis and hyperlipidemia, causing hepatic lipotoxicity. Furthermore, BCAA directly exacerbate hepatic lipotoxicity by reducing lipogenesis and inhibiting autophagy in the hepatocyte.

  17. Supplementation of branched-chain amino acids maintains the serum albumin level in the course of hepatocellular carcinoma recurrence.

    PubMed

    Kakazu, Eiji; Kondo, Yasuteru; Kogure, Takayuki; Ninomiya, Masashi; Kimura, Osamu; Iwata, Tomoaki; Morosawa, Tatsuki; Iwasaki, Takao; Shimosegawa, Tooru

    2013-01-01

    Hepatocellular carcinoma (HCC) is the third leading cause of cancer deaths worldwide. Serum albumin (Alb) is an important prognostic factor for patients with HCC. Moreover, plasma levels of branched-chain amino acids (BCAA), L-valine, L-leucine, and L-isoleucine, are commonly decreased in patients with cirrhosis. Accordingly, formulations of BCAA has been used to maintain the Alb level and prevent ascites in patients with cirrhosis. The aim of this study is to investigate differences in the changes in Alb between a group that received a BCAA formulation (n = 29) and a group given a standard diet (n = 60) in the course of HCC recurrences. All patients experienced more than one hospitalization (mean: 2.6; range: 2-10) owing to recurrence. The plasma BCAA concentration and BCAA-to-tyrosine ratio (BTR), which is a good indicator of the severity of hepatic parenchymal injury in patients with cirrhosis, were significantly correlated with Alb. We defined the changes in BCAA and Alb between recurrences as ΔBCAA and ΔAlb, respectively, and stratified the patients in both groups based on number of recurrences (3 < early, 3-5 middle, or 5 > later). There was also a positive correlation between ΔBCAA and ΔAlb. Interestingly, in the group with BCAA, ΔAlb and ΔBCAA were significantly smaller, especially in the middle period (3-5 recurrences), than in the group without BCAA. These results indicate that the BCAA supplementation could maintain the BCAA and Alb levels in the middle period (3-5 recurrences). BCAA formulation is useful for hypoalbuminemia in the course of HCC recurrence.

  18. 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

  19. Branched-Chain Amino Acids Are Required for the Survival and Virulence of Actinobacillus pleuropneumoniae in Swine▿

    PubMed Central

    Subashchandrabose, Sargurunathan; LeVeque, Rhiannon M.; Wagner, Trevor K.; Kirkwood, Roy N.; Kiupel, Matti; Mulks, Martha H.

    2009-01-01

    In Actinobacillus pleuropneumoniae, which causes porcine pleuropneumonia, ilvI was identified as an in vivo-induced (ivi) gene and encodes the enzyme acetohydroxyacid synthase (AHAS) required for branched-chain amino acid (BCAA) biosynthesis. ilvI and 7 of 32 additional ivi promoters were upregulated in vitro when grown in chemically defined medium (CDM) lacking BCAA. Based on these observations, we hypothesized that BCAA would be found at limiting concentrations in pulmonary secretions and that A. pleuropneumoniae mutants unable to synthesize BCAA would be attenuated in a porcine infection model. Quantitation of free amino acids in porcine pulmonary epithelial lining fluid showed concentrations of BCAA ranging from 8 to 30 μmol/liter, which is 10 to 17% of the concentration in plasma. The expression of both ilvI and lrp, a global regulator that is required for ilvI expression, was strongly upregulated in CDM containing concentrations of BCAA similar to those found in pulmonary secretions. Deletion-disruption mutants of ilvI and lrp were both auxotrophic for BCAA in CDM and attenuated compared to wild-type A. pleuropneumoniae in competitive index experiments in a pig infection model. Wild-type A. pleuropneumoniae grew in CDM+BCAA but not in CDM−BCAA in the presence of sulfonylurea AHAS inhibitors. These results clearly demonstrate that BCAA availability is limited in the lungs and support the hypothesis that A. pleuropneumoniae, and potentially other pulmonary pathogens, uses limitation of BCAA as a cue to regulate the expression of genes required for survival and virulence. These results further suggest a potential role for AHAS inhibitors as antimicrobial agents against pulmonary pathogens. PMID:19703979

  20. Introduction of unsaturation into the N-n-alkyl chain of the nicotinic receptor antagonists, NONI and NDNI: effect on affinity and selectivity.

    PubMed

    Sumithran, Sangeetha P; Crooks, Peter A; Xu, Rui; Zhu, Jun; Deaciuc, Agripina G; Wilkins, Lincoln H; Dwoskin, Linda P

    2005-08-29

    N-n-octylnicotinium iodide (NONI) and N-n-decylnicotinium iodide (NDNI) are selective nicotinic receptor (nAChR) antagonists mediating nicotine-evoked striatal dopamine (DA) release, and inhibiting [3H]nicotine binding, respectively. This study evaluated effects of introducing unsaturation into the N-n-alkyl chains of NONI and NDNI on inhibition of [3H]nicotine and [3H]methyllycaconitine binding (alpha4beta2* and alpha7* nAChRs, respectively), (86)Rb+ efflux and [3H]DA release (agonist or antagonist effects at alpha4beta2* and alpha6beta2*-containing nAChRs, respectively). In the NONI series, introduction of a C3-cis- (NONB3c), C3-trans- (NONB3t), C7-double-bond (NONB7e), or C3-triple-bond (NONB3y) afforded a 4-fold to 250-fold increased affinity for [3H]nicotine binding sites compared with NONI. NONB7e and NONB3y inhibited nicotine-evoked 86Rb+ efflux, indicating alpha4beta2* antagonism. NONI analogs exhibited a 3-fold to 8-fold greater potency inhibiting nicotine-evoked [3H]DA overflow compared with NONI (IC50 = 0.62 microM; Imax = 89%), with no change in Imax, except for NONB3y (Imax = 50%). In the NDNI series, introduction of a C4-cis- (NDNB4c), C4-trans-double-bond (NDNB4t), or C3-triple-bond (NDNB3y) afforded a 4-fold to 80-fold decreased affinity for [3H]nicotine binding sites compared with NDNI, whereas introduction of a C9 double-bond (NDNB9e) did not alter affinity. NDNB3y and NDNB4t inhibited nicotine-evoked 86Rb+ efflux, indicating antagonism at alpha4beta2* nAChRs. Although NDNI had no effect, NDNB4t and NDNB9e potently inhibited nicotine-evoked [3H]DA overflow (IC50 = 0.02-0.14 microM, Imax = 90%), as did NDNB4c (IC50 = 0.08 microM; Imax = 50%), whereas NDNB3y showed no inhibition. None of the analogs had significant affinity for alpha7* nAChRs. Thus, unsaturated NONI analogs had enhanced affinity at alpha4beta2*- and alpha6beta2*-containing nAChRs, however a general reduction of affinity at alpha4beta2* and an uncovering of antagonist effects at

  1. Use of short chain alkyl imidazolium ionic liquids for on-line stacking and sweeping of methotrexate, flinic acid and folic acid: their application to biological fluids.

    PubMed

    Abd El-Hady, Deia; Albishri, Hassan M; Rengarajan, Rajesh; Wätzig, Hermann

    2014-07-01

    Methotrexate (MTX) is widely used for the treatment of many types of cancer. Folinic acid (FNA) and folic acid (FA) were usually simultaneously supplemented with MTX to reduce the side effects of a folate deficiency. This study, for the first time, included on-line sample preconcentration by stacking and sweeping techniques under reduced or enhanced electric conductivity in the sample region using short chain alkyl imidazolium ionic liquids (ILs) as micelle forming agents for analyte focusing. Both analyte focusing by micelle collapse (AFMC) and sweeping-MEKC had been investigated for the comparison of their effectiveness to examine simultaneously MTX, FNA and FA in plasma and urine under physiological conditions. In sweeping-MEKC, the sample solution without micelles was hydrodynamically injected as a long plug into a fused-silica capillary pre-filled with phosphate buffer containing 3.0 mol/L of 1-butyl-3-methylimidazolium bromide (BMIMBr). Using AFMC, the analytes were prepared in BMIMBr micellar matrix and hydrodynamically injected into the phosphate buffer without IL micelles. The conductivity ratio between BGE and sample (γ, BGE/sample) was optimized to be 3.0 in sweeping-MEKC and 0.33 in AFMC resulting the adequate separation of analytes within 4.0 min. To reduce the possibility of BMIMBr adsorption, an appropriate rinsing protocol was used. The limits of detection were calculated as 0.1 ng/mL MTX, 0.05 ng/mL FNA and 0.05 ng/mL FA by sweeping-MEKC and 0.5 ng/mL MTX, 0.3 ng/mL FNA and 0.3 ng/mL FA by AFMC. The accuracy was tested by recovery in plasma and urine matrices giving values ranging between 90 and 110%. Both stacking and sweeping by BMIMBr could be successfully used for the rapid, selective and sensitive determination of pharmaceuticals in complex matrices due to its fascinating properties, including high conductivity, good thermal stability and ability to form different types of interactions by electrostatic, hydrophobic, hydrogen bonding and

  2. An asymptotic analysis of chain-branching ignition in the laminar wake of a splitter plate separating streams of hydrogen and oxygen

    NASA Astrophysics Data System (ADS)

    Sánchez, A. L.; Iglesias, I.; Liñán, A.

    1998-09-01

    The chain-branching process leading to ignition in the high-temperature laminar wake that forms at the trailing edge of a thin splitter plate separating a stream of hydrogen from a stream of oxygen is investigated with a reduced chemistry description that employs H as the only chain-branching radical not in steady state. The analysis presented covers ignition events occurring in the Rott-Hakkinen and Goldstein regions, where self-similar solutions for the different flow variables are available. It is found that the initiation reactions, which create the first radicals, are only important in a relatively small initial region, becoming negligible downstream as the radical mole fractions increase to values larger than the ratio of the characteristic branching time to the characteristic initiation time, a very small quantity at temperatures of practical interest. As a result, most of the ignition history is controlled by the autocatalytic branching reactions, giving rise to a radical pool that increases exponentially with distance in a process that is described by using as a large parameter the ratio of the streamwise distance to the downstream extent of the initial region where initiation reactions are significant. Comparisons of the asymptotic results with numerical integrations of the conservation equations reveal that a three-term expansion for the H-atom profile is necessary in this case to provide an accurate prediction for the ignition distance.

  3. Analysis of the LIV system of Campylobacter jejuni reveals alternative roles for LivJ and LivK in commensalism beyond branched-chain amino acid transport.

    PubMed

    Ribardo, Deborah A; Hendrixson, David R

    2011-11-01

    Campylobacter jejuni is a leading cause of diarrheal disease in humans and an intestinal commensal in poultry and other agriculturally important animals. These zoonotic infections result in significant amounts of C. jejuni present in the food supply to contribute to disease in humans. We previously found that a transposon insertion in Cjj81176_1038, encoding a homolog of the Escherichia coli LivJ periplasmic binding protein of the leucine, isoleucine, and valine (LIV) branched-chain amino acid transport system, reduced the commensal colonization capacity of C. jejuni 81-176 in chicks. Cjj81176_1038 is the first gene of a six-gene locus that encodes homologous components of the E. coli LIV system. By analyzing mutants with in-frame deletions of individual genes or pairs of genes, we found that this system constitutes a LIV transport system in C. jejuni responsible for a high level of leucine acquisition and, to a lesser extent, isoleucine and valine acquisition. Despite each LIV protein being required for branched-chain amino acid transport, only the LivJ and LivK periplasmic binding proteins were required for wild-type levels of commensal colonization of chicks. All LIV permease and ATPase components were dispensable for in vivo growth. These results suggest that the biological functions of LivJ and LivK for colonization are more complex than previously hypothesized and extend beyond a role for binding and acquiring branched-chain amino acids during commensalism. In contrast to other studies indicating a requirement and utilization of other specific amino acids for colonization, acquisition of branched-chain amino acids does not appear to be a determinant for C. jejuni during commensalism.

  4. 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.

  5. 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.

  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. 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

  8. Anionic Synthesis and Rheological Characterization of Poly(p-methylstyrene) Model Comb Architectures with a Defined and Very Low Degree of Long Chain Branching.

    PubMed

    Kempf, Michael; Barroso, Vitor C; Wilhelm, Manfred

    2010-12-15

    A method is presented for the synthesis of defined sparsely branched polystyrene-based homopolymer model combs. By the use of poly(p-methylstyrene) (PpMS) as backbone and side chains, a low, but well controlled amount of branching of typically less than 1 mol-% (e.g., 1 branch per approx. 200 backbone C-atoms) can be achieved. The used anionic synthesis offers full control of the molecular weight in combination with low polydispersity. Molecular weight and polydispersity were determined by SEC-MALLS, confirming the well defined synthesis with low polydispersity ($\\overline {{\\rm M}} _{{\\rm w}} /\\overline {{\\rm M}} _{{\\rm n}} $ < 1.07). The melt rheological properties of the synthesized linear and comb polymers were obtained in both oscillatory shear and uniaxial extensional flow. Using the so-called van Gurp-Palmen plot, clear differences between both synthesized topologies are clearly seen. The appearance of a second minimum for lower values of the complex modulus in shear is a clear indication of a second relaxation process attributable to the entangled side chains. The presence of the entangled side chains is responsible for the observed strain hardening obtained in extensional viscosity experiments, as compared to the linear polymers. These model samples open up the possibility to compare different advanced rheological methods, e.g., FT-rheology or extensional rheology, towards limiting sensitivity.

  9. 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...

  10. 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.

  11. Structure-Antibacterial Activity Relationships of Imidazolium-Type Ionic Liquid Monomers, Poly(ionic liquids) and Poly(ionic liquid) Membranes: Effect of Alkyl Chain Length and Cations.

    PubMed

    Zheng, Zhiqiang; Xu, Qiming; Guo, Jiangna; Qin, Jing; Mao, Hailei; Wang, Bin; Yan, Feng

    2016-05-25

    The structure-antibacterial activity relationship between the small molecular compounds and polymers are still elusive. Here, imidazolium-type ionic liquid (IL) monomers and their corresponding poly(ionic liquids) (PILs) and poly(ionic liquid) membranes were synthesized. The effect of chemical structure, including carbon chain length of substitution at the N3 position and charge density of cations (mono- or bis-imidazolium) on the antimicrobial activities against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was investigated by determination of minimum inhibitory concentration (MIC). The antibacterial activities of both ILs and PILs were improved with the increase of the alkyl chain length and higher charge density (bis-cations) of imidazolium cations. Moreover, PILs exhibited lower MIC values relative to the IL monomers. However, the antibacterial activities of PIL membranes showed no correlation to those of their analogous small molecule IL monomers and PILs, which increased with the charge density (bis-cations) while decreasing with the increase of alkyl chain length. The results indicated that antibacterial property studies on small molecules and homopolymers may not provide a solid basis for evaluating that in corresponding polymer membranes.

  12. Branched-chain amino acids and arginine supplementation attenuates skeletal muscle proteolysis induced by moderate exercise in young individuals.

    PubMed

    Matsumoto, K; Mizuno, M; Mizuno, T; Dilling-Hansen, B; Lahoz, A; Bertelsen, V; Münster, H; Jordening, H; Hamada, K; Doi, T

    2007-06-01

    This study aimed at evaluating the effect of a single oral intake of branched-chain amino acids (BCAA) with Arg on skeletal muscle protein metabolism during moderate exercise in young individuals. Eight healthy volunteers (4 males and 4 females, means +/- SEM, 26 +/- 1 yrs, 177.8 +/- 3.7 cm, 72.6 +/- 3.9 kg) were studied in a randomized double-blind placebo-controlled cross-over trial. The subjects performed 3 bouts of 20-min cycling exercise (5-min break between each bout) at 126 +/- 13 W corresponding to 50 % of the maximal work intensity. A single oral supplement of either a BCAA drink containing 2 g of BCAA and 0.5 g of Arg or an isocaloric placebo drink was given at 10 min of the 1st exercise bout. Both arterial and venous blood samples were simultaneously taken from the radial artery and the femoral vein, respectively. Blood flow in the femoral artery was determined using the ultrasound Doppler technique. The blood sampling and blood flow measurements were performed at rest, every 10 min during each exercise bout. Net balance of BCAA and Phe across the leg muscles were measured by the arteriovenous difference method. The BCAA ingestion resulted in increases in both the plasma BCAA concentration and BCAA uptake into the working leg. The Phe release from the leg during exercise significantly increased as compared to the basal level in the placebo trial (0.97 +/- 0.28 vs. 0.23 +/- 0.22 micromol/min, p < 0.05). In the BCAA trial, the cumulative Phe release from the leg during the 3rd exercise bout was significantly lower than that in the placebo trial (5.0 +/- 7.4 vs. 35.9 +/- 13.2 micromol/25 min, p < 0.05). These results suggest that endurance exercise at moderate intensity enhances proteolysis in working muscles, and a single oral intake of 2 g of BCAA with Arg at onset of exercise effectively suppresses exercise-induced skeletal muscle proteolysis.

  13. Lipid metabolism during bacterial growth, sporulation, and germination: differential synthesis of individual branched- and normal-chain fatty acids during spore germination and outgrowth of Bacillus thuringiensis.

    PubMed

    Nickerson, K W; Bulla, L A; Mounts, T L

    1975-12-01

    The biosynthesis of individual branched- and normal-chain fatty acids during Bacillus thuringiensis spore germination and outgrowth was studied by comparing pulsed and continuous labeling of these fatty acids with [U-14C]acetate. The relative specific activity of each fatty acid varies with time as the cell progresses through outgrowth. However, fatty acid synthesis does occur in two distinct phases. Upon germination, acetate is incorporated only into the iso-isomers i-C13, i-C14, and i-C16; no normal or anteiso synthesis occurs. Subsequent to T30, the full complement of branched- and normal-chain homologues is formed and there is a dramatic enhancement in the overall rate of fatty acid synthesis. Significantly, this rate increase coincides with a marked shift from the synthesis of short-chain to long-chain fatty acids. These findings illustrate a dichotomy in synthesis that may result from initial fatty acid formation by preexisting spore fatty acid biosynthetic enzymes in the absence of de novo protein synthesis. Elucidation of the timing and kinetics of individual fatty acid formation provides a biochemical profile of activities directly related to membrane differentiation and cellular development.

  14. Seizure control by derivatives of medium chain fatty acids associated with the ketogenic diet show novel branching-point structure for enhanced potency.

    PubMed

    Chang, Pishan; Zuckermann, Alexandra M E; Williams, Sophie; Close, Adam J; Cano-Jaimez, Marife; McEvoy, James P; Spencer, John; Walker, Matthew C; Williams, Robin S B

    2015-01-01

    The medium chain triglyceride (MCT) ketogenic diet is a major treatment of drug-resistant epilepsy but is problematic, particularly in adults, because of poor tolerability. Branched derivatives of octanoic acid (OA), a medium chain fat provided in the diet have been suggested as potential new treatments for drug-resistant epilepsy, but the structural basis of this functionality has not been determined. Here we investigate structural variants of branched medium chain fatty acids as new seizure-control treatments. We initially employ a series of methyl-branched OA derivatives, and using the GABAA receptor antagonist pentylenetetrazol to induce seizure-like activity in rat hippocampal slices, we show a strong, branch-point-specific activity that improves upon the related epilepsy treatment valproic acid. Using low magnesium conditions to induce glutamate excitotoxicity in rat primary hippocampal neuronal cultures for the assessment of neuroprotection, we also show a structural dependence identical to that for seizure control, suggesting a related mechanism of action for these compounds in both seizure control and neuroprotection. In contrast, the effect of these compounds on histone deacetylase (HDAC) inhibition, associated with teratogenicity, shows no correlation with therapeutic efficacy. Furthermore, small structural modifications of the starting compounds provide active compounds without HDAC inhibitory effects. Finally, using multiple in vivo seizure models, we identify potent lead candidates for the treatment of epilepsy. This study therefore identifies a novel family of fatty acids, related to the MCT ketogenic diet, that show promise as new treatments for epilepsy control and possibly other MCT ketogenic diet-responding conditions, such as Alzheimer disease.

  15. Analytic study of the chain dark decomposition reaction of iodides - atomic iodine donors - in the active medium of a pulsed chemical oxygen-iodine laser: 2. Limiting parameters of the branching chain dark decomposition reaction of iodides

    SciTech Connect

    Andreeva, Tamara L; Kuznetsova, S V; Maslov, Aleksandr I; Sorokin, Vadim N

    2009-08-31

    The final stages in the development of a branching chain decomposition reaction of iodide in the active medium of a pulsed chemical oxygen-iodine laser (COIL) are analysed. Approximate expressions are derived to calculate the limiting parameters of the chain reaction: the final degree of iodide decomposition, the maximum concentration of excited iodine atoms, the time of its achievement, and concentrations of singlet oxygen and iodide at that moment. The limiting parameters, calculated by using these expressions for a typical composition of the active medium of a pulsed COIL, well coincide with the results of numerical calculations. (active media)

  16. 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.

  17. Determination of rate constants and branching ratios for TCE degradation by zero-valent iron using a chain decay multispecies model.

    PubMed

    Hwang, Hyoun-Tae; Jeen, Sung-Wook; Sudicky, Edward A; Illman, Walter A

    2015-01-01

    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. 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

  19. Genetic Evidence That Chain Length and Branch Point Distributions Are Linked Determinants of Starch Granule Formation in Arabidopsis1[W][OPEN

    PubMed Central

    Pfister, Barbara; Lu, Kuan-Jen; Eicke, Simona; Feil, Regina; Lunn, John E.; Streb, Sebastian; Zeeman, Samuel C.

    2014-01-01

    The major component of starch is the branched glucan amylopectin. Structural features of amylopectin, such as the branching pattern and the chain length distribution, are thought to be key factors that enable it to form semicrystalline starch granules. We varied both structural parameters by creating Arabidopsis (Arabidopsis thaliana) mutants lacking combinations of starch synthases (SSs) SS1, SS2, and SS3 (to vary chain lengths) and the debranching enzyme ISOAMYLASE1-ISOAMYLASE2 (ISA; to alter branching pattern). The isa mutant accumulates primarily phytoglycogen in leaf mesophyll cells, with only small amounts of starch in other cell types (epidermis and bundle sheath cells). This balance can be significantly shifted by mutating different SSs. Mutation of SS1 promoted starch synthesis, restoring granules in mesophyll cell plastids. Mutation of SS2 decreased starch synthesis, abolishing granules in epidermal and bundle sheath cells. Thus, the types of SSs present affect the crystallinity and thus the solubility of the glucans made, compensating for or compounding the effects of an aberrant branching pattern. Interestingly, ss2 mutant plants contained small amounts of phytoglycogen in addition to aberrant starch. Likewise, ss2ss3 plants contained phytoglycogen, but were almost devoid of glucan despite retaining other SS isoforms. Surprisingly, glucan production was restored in the ss2ss3isa triple mutants, indicating that SS activity in ss2ss3 per se is not limiting but that the isoamylase suppresses glucan accumulation. We conclude that loss of only SSs can cause phytoglycogen production. This is readily degraded by isoamylase and other enzymes so it does not accumulate and was previously unnoticed. PMID:24965177

  20. 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.

  1. Metabolic Fate of Branched-Chain Amino Acids During Adipogenesis, in Adipocytes From Obese Mice and C2C12 Myotubes.

    PubMed

    Estrada-Alcalde, Isabela; Tenorio-Guzman, Miriam R; Tovar, Armando R; Salinas-Rubio, Daniela; Torre-Villalvazo, Ivan; Torres, Nimbe; Noriega, Lilia G

    2017-04-01

    Branched-chain amino acid (BCAA) catabolism is regulated by the branched-chain aminotransferase (BCAT2) and the branched-chain α-keto acid dehydrogenase complex (BCKDH). BCAT2 and BCKDH expression and activity are modified during adipogenesis and altered in adipose tissues of mice with genetic or diet-induced obesity. However, little is known about how these modifications and alterations affect the intracellular metabolic fate of BCAAs during adipogenesis, in adipocytes from mice fed a control or high-fat diet or in C2C12 myotubes. Here, we demonstrate that BCAAs are mainly incorporated into proteins during the early stages of adipocyte differentiation. However, they are oxidized and incorporated into lipids during the late days of differentiation. Conversely, 92% and 97% of BCAA were oxidized, 1.6% and 6% were used for protein synthesis and 1.2% and 1.5% were incorporated into lipids in adipocytes from epididymal and subcutaneous adipose tissue, respectively. All three pathways were decreased in adipocytes from mice fed a high-fat diet. In C2C12 myotubes, leucine is mainly used for protein synthesis and palmitate is incorporated into lipids. Interestingly, leucine decreased both palmitate oxidation and its incorporation to lipids and proteins; and palmitate increased leucine oxidation and decreased its incorporation to lipids and proteins in a dose-dependent manner. These results demonstrate that BCAA metabolic fate differs between the early and late stages of adipocyte differentiation and in adipocytes from mice fed a control or high-fat diet; and that leucine affects the metabolic fate of palmitate and vice versa in C2C12 myotubes. J. Cell. Biochem. 118: 808-818, 2017. © 2016 Wiley Periodicals, Inc.

  2. Apoptotic signaling pathways induced by acute administration of branched-chain amino acids in an animal model of maple syrup urine disease.

    PubMed

    Vilela, Thais C; Scaini, Giselli; Furlanetto, Camila B; Pasquali, Matheus A B; Santos, João Paulo A; Gelain, Daniel P; Moreira, José Cláudio F; Schuck, Patrícia F; Ferreira, Gustavo C; Streck, Emilio L

    2017-02-01

    Maple Syrup Urine Disease (MSUD) is an inborn error of metabolism caused by a deficiency of the branched-chain α-keto acid dehydrogenase complex activity. This blockage leads to accumulation of the branched-chain amino acids leucine, isoleucine and valine, as well as their corresponding α-keto acids and α-hydroxy acids. The affected patients present severe neurological symptoms, such as coma and seizures, as well as edema and cerebral atrophy. Considering that the mechanisms of the neurological symptoms presented by MSUD patients are still poorly understood, in this study, protein levels of apoptotic factors are measured, such as Bcl-2, Bcl-xL, Bax, caspase-3 and -8 in hippocampus and cerebral cortex of rats submitted to acute administration of branched-chain amino acids during their development. The results in this study demonstrated that BCAA acute exposure during the early postnatal period did not significantly change Bcl-2, Bcl-xL, Bax and caspase-8 protein levels. However, the Bax/Bcl-2 ratio and procaspase-3 protein levels were decreased in hippocampus. On the other hand, acute administration of BCAA in 30-day-old rats increase in Bax/Bcl-2 ratio followed by an increased caspase-3 activity in cerebral cortex, whereas BCAA induces apoptosis in hippocampus through activation and cleavage of caspase-3 and -8 without changing the Bax/Bcl-2 ratio. In conclusion, the results suggest that apoptosis could be of pivotal importance in the developmental neurotoxic effects of BCAA. In addition, the current studies also suggest that multiple mechanisms may be involved in BCAA-induced apoptosis in the cerebral cortex and hippocampus.

  3. An enzyme in yeast mitochondria that catalyzes a step in branched-chain amino acid biosynthesis also functions in mitochondrial DNA stability.

    PubMed Central

    Zelenaya-Troitskaya, O; Perlman, P S; Butow, R A

    1995-01-01

    The yeast mitochondrial high mobility group protein Abf2p is required, under certain growth conditions, for the maintenance of wild-type (rho+) mitochondrial DNA (mtDNA). We have identified a multicopy suppressor of the mtDNA instability phenotype of cells with a null allele of the ABF2 gene (delta abf2). The suppressor is a known gene, ILV5, encoding the mitochondrial protein, acetohydroxy acid reductoisomerase, which catalyzes a step in branched-chain amino acid biosynthesis. Efficient suppression occurs with just a 2- to 3-fold increase in ILV5 copy number. Moreover, in delta abf2 cells with a single copy of ILV5, changes in mtDNA stability correlate directly with changes in conditions that are known to affect ILV5 expression. Wild-type mtDNA is unstable in cells with an ILV5 null mutation (delta ilv5), leading to the production of mostly rho- petite mutants. The instability of rho+ mtDNA in delta ilv5 cells is not simply a consequence of a block in branched-chain amino acid biosynthesis, since mtDNA is stable in cells with a null allele of the ILV2 gene, which encodes another enzyme of that pathway. The most severe instability of rho+ mtDNA is observed in cells with null alleles of both ABF2 and ILV5. We suggest that ILV5 encodes a bifunctional protein required for branched-chain amino acid biosynthesis and for the maintenance of rho+ mtDNA. Images PMID:7621838

  4. Effects of intraduodenal feeding of a branched-chain amino acid-rich solution on ammonia-induced encephalopathy in liver-injured rats.

    PubMed

    Hayashi, S; Watanabe, A; Shiota, T; Obata, T; Takei, N; Sakata, T; Nagashima, H

    1982-12-01

    A preventive effect of intraduodenal prefeeding of a branched-chain amino acid (BCAA)-rich solution on ammonia-induced encephalopathy was investigated with carbon tetrachloride CC14-injured rats with the elevated levels of blood ammonia. Five out of six cirrhotic rats, to which an electrolyte solution alone was preinfused for 24 hours, fell into coma following ammonia acetate injection and two comatose rats died. However, no cirrhotic rats preinfused with a BCAA-rich solution died and only two out of the six showed coma with complete recovery. The similar preventive effect could not be observed in rats with acute liver injury.

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  8. Control over phase behavior and solution structure of hairy-rod polyfluorene by means of side-chain length and branching.

    PubMed

    Knaapila, M; Stepanyan, R; Torkkeli, M; Garamus, V M; Galbrecht, F; Nehls, B S; Preis, E; Scherf, U; Monkman, A P

    2008-05-01

    We present guidelines on how the solution structure of pi -conjugated hairy-rod polyfluorenes is controlled by the side-chain length and branching. First, the semiquantitative mean-field theory is formulated to predict the phase behavior of the system as a function of side-chain beads (N). The phase transition at N=N{ *} separates a lyotropic phase with solvent coexistence (NN{ *}). The membrane phase transforms into the isotropic phase of dissolved rodlike polymers at the temperature T_{mem}{ *}(N), which decreases both with N and with the degree of side-chain branching. This picture is complemented by polymer demixing with the transition temperature T_{IN}{ *}(N), which decreases with N . For NN{ *}, stable membranes are predicted for T_{IN}{ *}chain branching was controlled by (9,9-dioctylfluorene)/(9,9-bis(2-ethylhexyl)fluorene) (F8/F2/6) random copolymers. The proportion of F8 to F2/6 repeat units was 100:0, 95:5, 90:10, 50:50, and 0:100. In accordance with the theory, lyotropic, membrane, and isotropic phases with the corresponding phase transitions were observed. For NN{ *}. T_{mem}{ *}(N) decreases from 340 K to 280 K for N > or = 8 . For copolymers, the membrane phase is found when the fraction of F8 units is at least 90%, T_{mem}{ *} decreasing with this fraction. The membrane phase contains three material types: loose sheets of two polymer layers, a better packed beta phase, and dissolved polymer. For N > or = 7 and T

  9. 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.

  10. 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.

  11. Morphology and phase controlled cobalt nanostructures in magnetic polypropylene nanocomposites: the role of alkyl chain-length in maleic anhydride grafted polypropylene.

    PubMed

    He, Qingliang; Yuan, Tingting; Luo, Zhiping; Haldolaarachchige, Neel; Young, David P; Wei, Suying; Guo, Zhanhu

    2013-04-04

    A novel function of maleic anhydride grafted polypropylene (PP) with different backbone chain-lengths was demonstrated, i.e., in controlling the cobalt morphologies (dispersed polyhedral vs. assembled chain nanostructure), crystalline structures (ε- vs. β-phase), and magnetic property (242 vs. 808 Oe) in the synthesized magnetic PP nanocomposites.

  12. 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.

  13. 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

    2015-09-24

    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

  14. Genetic Predisposition to an Impaired Metabolism of the Branched-Chain Amino Acids and Risk of Type 2 Diabetes: A Mendelian Randomisation Analysis

    PubMed Central

    Lotta, Luca A.; Scott, Robert A.; Luan, Jian’an; Tillin, Therese; Stewart, Isobel D.; Perry, John R. B.; Karoly, Edward D.; Forouhi, Nita G.; Zierath, Juleen R.; Savage, David B.; Griffin, Julian L.; Hingorani, Aroon D.; Khaw, Kay-Tee; O’Rahilly, Stephen; Langenberg, Claudia

    2016-01-01

    Background Higher circulating levels of the branched-chain amino acids (BCAAs; i.e., isoleucine, leucine, and valine) are strongly associated with higher type 2 diabetes risk, but it is not known whether this association is causal. We undertook large-scale human genetic analyses to address this question. Methods and Findings Genome-wide studies of BCAA levels in 16,596 individuals revealed five genomic regions associated at genome-wide levels of significance (p < 5 × 10−8). The strongest signal was 21 kb upstream of the PPM1K gene (beta in standard deviations [SDs] of leucine per allele = 0.08, p = 3.9 × 10−25), encoding an activator of the mitochondrial branched-chain alpha-ketoacid dehydrogenase (BCKD) responsible for the rate-limiting step in BCAA catabolism. In another analysis, in up to 47,877 cases of type 2 diabetes and 267,694 controls, a genetically predicted difference of 1 SD in amino acid level was associated with an odds ratio for type 2 diabetes of 1.44 (95% CI 1.26–1.65, p = 9.5 × 10−8) for isoleucine, 1.85 (95% CI 1.41–2.42, p = 7.3 × 10−6) for leucine, and 1.54 (95% CI 1.28–1.84, p = 4.2 × 10−6) for valine. Estimates were highly consistent with those from prospective observational studies of the association between BCAA levels and incident type 2 diabetes in a meta-analysis of 1,992 cases and 4,319 non-cases. Metabolome-wide association analyses of BCAA-raising alleles revealed high specificity to the BCAA pathway and an accumulation of metabolites upstream of branched-chain alpha-ketoacid oxidation, consistent with reduced BCKD activity. Limitations of this study are that, while the association of genetic variants appeared highly specific, the possibility of pleiotropic associations cannot be entirely excluded. Similar to other complex phenotypes, genetic scores used in the study captured a limited proportion of the heritability in BCAA levels. Therefore, it is possible that only some of the mechanisms that increase BCAA

  15. 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.

  16. [Usefulness of branched-chain amino acid (BCAA)-enriched nutrient mixture for nutritional treatment undergoing endoscopic treatment for esophageal varices].

    PubMed

    Shibata, Naozumi; Matsui, Hidetaka; Takeshita, Eiji; Yokota, Tomoyuki; Higaki, Naoyuki; Murakami, Hidehiro; Ikeda, Yoshiou; Minami, Hisaka; Matsuura, Bunzo; Onji, Morikazu

    2005-07-01

    We investigated the alteration of nutritional status in 144 patients who were treated for the first time with endoscopic sclerotherapy or endoscopic variceal ligation during their therapies. The serum levels of albumin, cholinesterase and total cholesterol were compared before and after treatment. The serum level of cholinesterase declined significantly. To investigate the impact of aging on the changes of nutritional status we divided all patients into two groups: (1) under 65 years, and (2) over 65 years. The decline of serum albumin of elderly patients (n=65) was significantly greater than that of younger patients (n=79). A branched-chain amino acid (BCAA)-enriched nutrient mixture for nutritional treatment significantly suppressed the decline of serum albumin in elderly patients. Nutritional treatment with a BCAA-enriched nutrient mixture should be considered during endoscopic therapy for esophageal varices, especially in elderly patients.

  17. Docking and quantitative structure-activity relationship studies for sulfonyl hydrazides as inhibitors of cytosolic human branched-chain amino acid aminotransferase.

    PubMed

    Caballero, Julio; Vergara-Jaque, Ariela; Fernández, Michael; Coll, Deysma

    2009-11-01

    We have performed the docking of sulfonyl hydrazides complexed with cytosolic branched-chain amino acid aminotransferase (BCATc) to study the orientations and preferred active conformations of these inhibitors. The study was conducted on a selected set of 20 compounds with variation in structure and activity. In addition, the predicted inhibitor concentration (IC(50)) of the sulfonyl hydrazides as BCAT inhibitors were obtained by a quantitative structure-activity relationship (QSAR) method using three-dimensional (3D) vectors. We found that three-dimensional molecule representation of structures based on electron diffraction (3D-MoRSE) scheme contains the most relevant information related to the studied activity. The statistical parameters [cross-validate correlation coefficient (Q(2) = 0.796) and fitted correlation coefficient (R(2) = 0.899)] validated the quality of the 3D-MoRSE predictive model for 16 compounds. Additionally, this model adequately predicted four compounds that were not included in the training set.

  18. Design, synthesis, and evaluation of omega-iodovinyl- and omega-iodoalkyl-substituted methyl-branched long-chain fatty acids

    SciTech Connect

    Goodman, M.M.; Callahan, A.P.; Knapp, F.F. Jr.

    1985-06-01

    The synthesis of a new methyl-branched fatty acid, (E)-19-iodo-3(RS)-methyl-18-nonadecenoic acid (19), is described. Methyl branching has been introduced at the 3-position to inhibit beta-oxidation and radioiodide has been attached as a trans-vinyl iodide. Preparation of 19 involved a 15-step sequence of reactions climaxing with formation of the methyl ester 18 by iododestannylation of methyl (E)-19-(tri-n-butylstannyl)-3(RS)-methyl-18-nonadecenoate (17) resulting from the reaction of n-Bu3SnH with methyl 3(RS)-methyl-18-nonadecynoate (16). Methyl branching was introduced at an early stage by Friedel-Crafts acylation of thiophene with 3(RS)-methyl-4-carbomethoxybutanoyl chloride (3) generated from 3-methylglutaric anhydride. The new agent, (/sup 125/I)-19, showed high myocardial uptake (5 min, 4.89% dose/g; 30 min, 3.32% dose/g), good heart/blood (H/B) ratios (5 min, 5.4/1; 30 min, 4.3/1), and significantly greater myocardial retention in fasted rats than the corresponding straight-chain analogue 19-(/sup 125/I)-iodo-18-nonadecenoic acid (5 min, 3.52% dose/g, H/B = 4.8/1; 30 min, 1.19% dose/g, H/B = 1.6/1). Excellent myocardial images were obtained in rats after administration of (123I)-19 and confirmed the slow myocardial washout over a 60-min period. These data suggest that 19 is a good candidate for evaluation of heart disease involving aberrations in fatty acid metabolism by use of imaging techniques such as single photon emission computerized tomography (SPECT) where redistribution or washout should be minimized.

  19. 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.

  20. 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

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

    PubMed

    Lackey, Denise E; Lynch, Christopher J; Olson, Kristine C; Mostaedi, Rouzbeh; Ali, Mohamed; Smith, William H; Karpe, Fredrik; Humphreys, Sandy; Bedinger, Daniel H; Dunn, Tamara N; Thomas, Anthony P; Oort, Pieter J; Kieffer, Dorothy A; Amin, Rajesh; Bettaieb, Ahmed; Haj, Fawaz G; Permana, Paska; Anthony, Tracy G; Adams, Sean H

    2013-06-01

    Elevated blood branched-chain amino acids (BCAA) are often associated with insulin resistance and type 2 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 metabolism. We tested if expression of the mitochondrial BCAA oxidation checkpoint, branched-chain α-ketoacid dehydrogenase (BCKD) complex, is reduced in obese WAT and regulated by metabolic signals. WAT BCKD protein (E1α subunit) was significantly reduced by 35-50% in various obesity models (fa/fa rats, db/db mice, diet-induced obese mice), and BCKD component transcripts significantly lower in subcutaneous (SC) adipocytes from obese vs. lean Pima Indians. Treatment of 3T3-L1 adipocytes or mice with peroxisome proliferator-activated receptor-γ agonists increased WAT BCAA catabolism enzyme mRNAs, whereas the nonmetabolizable glucose analog 2-deoxy-d-glucose had the opposite effect. The results support the hypothesis that suboptimal insulin action and/or perturbed metabolic signals in WAT, as would be seen with insulin resistance/type 2 diabetes, could impair WAT BCAA utilization. However, cross-tissue flux studies comparing lean vs. insulin-sensitive or insulin-resistant obese subjects revealed an unexpected negligible uptake of BCAA from human abdominal SC WAT. This suggests that SC WAT may not be an important contributor to blood BCAA phenotypes associated with insulin resistance in the overnight-fasted state. mRNA abundances for BCAA catabolic enzymes were markedly reduced in omental (but not SC) WAT of obese persons with metabolic syndrome compared with weight-matched healthy obese subjects, raising the possibility that visceral WAT contributes to the BCAA metabolic phenotype of metabolically compromised individuals.

  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. Effect of lactation stage on the odd- and branched-chain milk fatty acids of dairy cattle under grazing and indoor conditions.

    PubMed

    Craninx, M; Steen, A; Van Laar, H; Van Nespen, T; Martín-Tereso, J; De Baets, B; Fievez, V

    2008-07-01

    The pattern of odd- and branched-chain fatty acids (OBCFA) in milk fat reflects rumen microbial activity and proportions of different rumen microbial groups. Therefore, these milk fatty acids (FA) are used to predict rumen proportions of volatile fatty acids, duodenal flow of microbial protein, and occurrence of rumen acidosis. However, current models do not correct for the potential effects of lactation stage on the level of OBCFA in milk fat. Hence, the objectives of this study were 1) to describe progressive changes related to lactation stage in concentrations of milk FA, with emphasis on the OBCFA, using the incomplete gamma function of Wood, and 2) to analyze whether lactation curves of milk FA on the one hand and milk production or milk fat content on the other hand coincide through evaluation of the correlation between the parameters of the Wood functions fitted to individual animal data. Data were collected from 2 trials in which milk FA during lactation were monitored. The first experiment was a stable trial with 2 groups of 10 cows receiving 2 dietary treatments from wk 1 to 40 of lactation. The second experiment was a grazing trial with 9 cows that were followed during the first 18 wk of lactation. Lactation curves of milk production, milk fat content, and individual milk FA were developed using the incomplete gamma function of Wood for each of the 3 dietary strategies separately. For almost all of the milk FA, lactation curve shapes were similar for all 3 dietary treatments. The OBCFA with chain lengths of 14 and 15 carbon atoms followed the lactation curves of the short- and medium-chain milk FA, which increased in early lactation. The OBCFA with chain length of 17 carbon atoms decreased during the early lactation period, following the pattern of milk long-chain fatty acids. The short- and medium-chain milk FA and OBCFA in the early lactation period seemed to be negatively correlated with the starting milk production and milk fat content, but

  5. 40 CFR 721.10283 - Poly[oxy(methyl-1,2-ethanediyl)], .alpha.-sulfo-.omega.-hydroxy-, C12-13-branched and linear...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-, 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....

  6. 40 CFR 721.10284 - Poly[oxy(methyl-1,2-ethanediyl)], .alpha.-sulfo-.omega.-hydroxy-, C14-15-branched and linear...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-, 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....

  7. Structure Effect of Some New Anticancer Pt(II) Complexes of Amino Acid Derivatives with Small Branched or Linear Hydrocarbon Chains on Their DNA Interaction.

    PubMed

    Kantoury, Mahshid; Eslami Moghadam, Mahboube; Tarlani, Ali Akbar; Divsalar, Adeleh

    2016-07-01

    The aim of this study was to investigate the structure effect and identify the modes of binding of amino acid-Pt complexes to DNA molecule for cancer treatment. Hence, three novel water soluble platinum complexes, [Pt(phen)(R-gly)]NO3 (where phen is 1,10-phenanthroline, R-gly is methyl, amyl, and isopentyl-glycine), have been synthesized and characterized by spectroscopic methods, conductivity measurements, and chemical analysis. The anticancer activities of synthesized complexes were investigated against human breast cancer cell line of MDA-MB 231. The 50% cytotoxic concentration values were determined to be 42.5, 58, and 70 μm for methyl-, amyl-, and isopentyl-gly complexes, respectively. These complexes were interacted with calf thymus DNA (ct-DNA) via positive cooperative interaction. The modes of binding of the complexes to DNA were investigated by fluorescence spectroscopy and circular dichroism in combination with a molecular docking study. The result indicates that complexes with small or branched hydrocarbon chains can intercalate with DNA. This is while amyl complexes with linear chains interacted additionally via groove binding. The results of the negative value of Gibbs energy for binding of isopentyl-platinum to DNA and those of the molecular docking were coherent. Furthermore, the docking results demonstrated that hydrophobic interaction plays an important role in the complex-DNA interaction.

  8. P-type ATPase TAT-2 negatively regulates monomethyl branched-chain fatty acid mediated function in post-embryonic growth and development in C. elegans.

    PubMed

    Seamen, Emylie; Blanchette, Jennifer M; Han, Min

    2009-08-01

    Monomethyl branched-chain fatty acids (mmBCFAs) are essential for Caenorhabditis elegans growth and development. To identify factors acting downstream of mmBCFAs for their function in growth regulation, we conducted a genetic screen for suppressors of the L1 arrest that occurs in animals depleted of the 17-carbon mmBCFA C17ISO. Three of the suppressor mutations defined an unexpected player, the P-type ATPase TAT-2, which belongs to the flippase family of proteins that are implicated in mediating phospholipid bilayer asymmetry. We provide evidence that TAT-2, but not other TAT genes, has a specific role in antagonizing the regulatory activity of mmBCFAs in intestinal cells. Interestingly, we found that mutations in tat-2 also suppress the lethality caused by inhibition of the first step in sphingolipid biosynthesis. We further showed that the fatty acid side-chains of glycosylceramides contain 20%-30% mmBCFAs and that this fraction is greatly diminished in the absence of mmBCFA biosynthesis. These results suggest a model in which a C17ISO-containing sphingolipid may mediate the regulatory functions of mmBCFAs and is negatively regulated by TAT-2 in intestinal cells. This work indicates a novel connection between a P-type ATPase and the critical regulatory function of a specific fatty acid.

  9. Metabolic shifts and structural changes in the gut microbiota upon branched-chain amino acid supplementation in middle-aged mice.

    PubMed

    Yang, Zhan; Huang, Simo; Zou, Dayang; Dong, Derong; He, Xiaoming; Liu, Ningwei; Liu, Wei; Huang, Liuyu

    2016-12-01

    The importance of gut microbiota to health has gained extensive attention and is strongly correlated with diet. Dietary supplementation with a branched-chain amino acid-enriched mixture (BCAAem) exerts a variety of beneficial effects in mice and humans. In mice, BCAAem supplementation can promote longevity, but its influence on the gut ecosystem and the underlying mechanism remain unclear. To address this issue, BALB/C mice were fed a BCAAem-supplemented diet and their gut microbiomes were analysed by 16S rDNA sequencing. Quantitative polymerase chain reaction was performed to identify Bifidobacterium spp. in the gut, and gas chromatography-mass spectrometry was conducted for faecal-metabolite detection. The results showed that the structure of the gut microbiota changed, and BCAAem-supplementation in mice slowed the change speed of gut microbiota which is due to age. In addition, the abundance of the Akkermansia and Bifidobacterium increased in BCAAem-supplemented mice, while the ratio of Enterobacteriaceae decreased in BCAAem-supplemented mice. Moreover, 12 different metabolites, representing sugar and lipid metabolism, were altered between the supplemented and control groups. Thus, BCAAem influences the gut microbiota and gut metabolism. In addition, the BCAAem-supplemented group presented lower serum concentrations of lipopolysaccharide-binding protein. The changes are indicative of lower antigen loads in the host gut. These results suggest that dietary supplementation with BCAAem may be considered for improving health and promoting healthy aging.

  10. 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.

  11. 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.

  12. 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...

  13. 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.

  14. Structural and Thermodynamic Basis for Weak Interactions between Dihydrolipoamide Dehydrogenase and Subunit-binding Domain of the Branched-chain α-Ketoacid Dehydrogenase Complex*

    PubMed Central

    Brautigam, Chad A.; Wynn, R. Max; Chuang, Jacinta L.; Naik, Mandar T.; Young, Brittany B.; Huang, Tai-huang; Chuang, David T.

    2011-01-01

    The purified mammalian branched-chain α-ketoacid dehydrogenase complex (BCKDC), which catalyzes the oxidative decarboxylation of branched-chain α-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-Å 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 α-ketoacid dehydrogenase complexes. PMID:21543315

  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. Regioselective synthesis and biological profiling of butyric and phenylalkylcarboxylic esters derivated from D-mannose and xylitol: influence of alkyl chain length on acute toxicity.

    PubMed

    Pouillart, P; Douillet, O; Scappini, B; Gozzini, A; Santini, V; Grossi, A; Pagliai, G; Strippoli, P; Rigacci, L; Ronco, G; Villa, P

    1999-01-01

    Regiospecific synthesis of 12 novel n-butyric and phenylalkylcarboxylic monoesters of mannose and xylitol was achieved. The strategy adopted, avoided a tedious intramolecular transesterification step, previously described for the synthesis of analogous compounds and permitted the facile synthesis of a new generation of stable derivatives. The general tolerance of the drugs has been assayed after intravenous administration of a bolus dose into mice. Monobutyric esters showed a low toxicity commensurate with the requirements for future development. A relationship was observed between chain length and toxicity. In contrast, phenylacetic, 3-phenylpropionic and 4-phenylbutyric esters were found to be toxic. Phenylbutyric esters induced marked and specific neuromuscular damage. Preliminary biological investigations of the new series of monobutyric esters showed them to retain the benificial biological properties of butyric acid whilst remaining relatively non toxic. They induced an inhibition of in vitro proliferation of 10 human cases of de novo acute myeloid leukemia (AML) primary cultures and AML established cell lines. AML blasts growth appeared to be blocked and cell differentiation was established. Transcription and expression of maturation markers and finally apoptosis were observed. Moreover, human gamma-chain hemoglobin (HbF) synthesis in erythroleukemia cells was stimulated by monobutyric esters. Mannose and xylitol butyric derivatives would appear to have exciting potential in treatment of beta-Hemoglobinopathies, sickle cell anemia and cancer.

  17. Performance of a Branch Chain RNA In Situ Hybridization Assay for the Detection of High-risk Human Papillomavirus in Head and Neck Squamous Cell Carcinoma.

    PubMed

    Kerr, Darcy A; Arora, Kshitij S; Mahadevan, Krishnan K; Hornick, Jason L; Krane, Jeffrey F; Rivera, Miguel N; Ting, David T; Deshpande, Vikram; Faquin, William C

    2015-12-01

    High-risk human papillomavirus (HR-HPV) is a major etiologic agent in a subset of head and neck squamous cell carcinomas (HNSCCs), and its recognition has prognostic and predictive implications. The availability of a sensitive and specific test to assess HR-HPV status is limited. We evaluate an RNA in situ hybridization (ISH) method using branch chain technology to detect HR-HPV and compare its results with DNA ISH, p16 immunohistochemistry, and polymerase chain reaction (PCR). Tissue sections from 54 patients were stained with a manual RNA ISH assay (ViewRNA), which detects 14 HR-HPV types, an automated DNA ISH assay, and p16 immunohistochemistry. Most cases (83%, n=45) were also tested on an automated platform for 14 HR-HPV types and 1 limited to HPV 16/18. PCR was performed in all cases and was successful in 93% (n=50). The RNA ISH assay produced results in 96% of the cases with strong signals and was easily interpreted. HR-HPV was detected in more cases (63%, n=34) by RNA ISH than by DNA ISH (39%, n=21). Compared with PCR, both ISH platforms were 94% specific. RNA ISH was more sensitive (91%) than DNA ISH (65%), and RNA ISH correlated more strongly with p16 immunostaining. HPV 16 represented 89% of HR-HPV detected. The cocktail HPV 16/18 platform was concordant with the pooled HR-HPV assay in all expected cases. The automated assay demonstrated high concordance (96%) with the manual version, showed decreased background, and should allow for easy implementation into the workflow of the diagnostic pathology laboratory.

  18. 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.

  19. High concentration of branched-chain amino acids promotes oxidative stress, inflammation and migration of human peripheral blood mononuclear cells via mTORC1 activation.

    PubMed

    Zhenyukh, Olha; Civantos, Esther; Ruiz-Ortega, Marta; Sánchez, Maria Soledad; Vázquez, Clotilde; Peiró, Concepción; Egido, Jesús; Mas, Sebastián

    2017-03-01

    Leucine, isoleucine and valine are essential aminoacids termed branched-chain amino acids (BCAA) due to its aliphatic side-chain. In several pathological and physiological conditions increased BCAA plasma concentrations have been described. Elevated BCAA levels predict insulin resistance development. Moreover, BCAA levels higher than 2mmol/L are neurotoxic by inducing microglial activation in maple syrup urine disease. However, there are no studies about the direct effects of BCAA in circulating cells. We have explored whether BCAA could promote oxidative stress and pro-inflammatory status in peripheral blood mononuclear cells (PBMCs) obtained from healthy donors. In cultured PBMCs, 10mmol/L BCAA increased the production of reactive oxygen species (ROS) via both NADPH oxidase and the mitochondria, and activated Akt-mTOR signalling. By using several inhibitors and activators of these molecular pathways we have described that mTOR activation by BCAA is linked to ROS production and mitochondrial dysfunction. BCAA stimulated the activation of the redox-sensitive transcription factor NF-κB, which resulted in the release of pro-inflammatory molecules, such as interleukin-6, tumor necrosis factor-α, intracellular adhesion molecule-1 or CD40L, and the migration of PBMCs. In conclusion, elevated BCAA blood levels can promote the activation of circulating PBMCs, by a mechanism that involving ROS production and NF-κB pathway activation. These data suggest that high concentrations of BCAA could exert deleterious effects on circulating blood cells and therefore contribute to the pro-inflammatory and oxidative status observed in several pathophysiological conditions.

  20. 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.

  1. Effect of alkyl chain of room temperature ionic liquid (RTILs) on the phase behavior of [C2mim][C(n)SO4]/TX-100/cyclohexane microemulsions: solvent and rotational relaxation study.

    PubMed

    Ghosh, Surajit; Banerjee, Chiranjib; Mandal, Sarthak; Rao, Vishal Govind; Sarkar, Nilmoni

    2013-05-16

    In this investigation, we present microemulsions comprising a nonionic surfactant, Triton X-100 (TX-100), cyclohexane as nonpolar phase, and room temperature ionic liquids (RTILs) as a polar medium. To investigate the effect of alkyl chain length of ionic liquid on the physicochemical properties of microemulsions, we have used 1-ethyl-3-methylimidazolium n-butyl sulfate [C2mim][C4SO4], 1-ethyl-3-methylimidazolium n-hexyl sulfate [C2mim][C6SO4], and 1-ethyl-3-methylimidazolium n-octyl sulfate [C2mim][C8SO4] as polar media. The phase behavior of these ternary systems is investigated by direct observation of transition from clear transparent solution to turbid solution by using UV-vis spectrophotometer at 298 K. The single-phase region is found to increase with increase in chain length of RTIL anion. Dynamic light scattering (DLS) measurements revealed the formation of highly stable nano-sized RTIL-containing microemulsions. The size of the microemulsions increases with the addition of ionic liquid. The maximum increase in size is observed with the addition of [C2mim][C4SO4]. It is proposed that the long octyl chain of octyl sulfate allows the anion to align itself along the TX-100 molecules which increases the rigidity of microemulsions, whereas in case of [C2mim][C4SO4], the short butyl chain is apparently unable to do the same. The dynamics of solvent and rotational relaxation of coumarin 480 (C-480) has also been investigated in these ionic liquid containing microemulsions ([C2mim][C4SO4]/TX-100/cyclohexane, [C2mim][C6SO4]/TX-100/cyclohexane, and [C2mim][C8SO4]/TX-100/cyclohexane) using picosecond time-resolved fluorescence spectroscopy. In RTIL microemulsions, solvent relaxation becomes retarded compared to neat RTIL. We have also shown that with increasing R value, the solvation dynamics becomes faster and the decrease in average solvation time is more pronounced in [C2mim][C4SO4]/TX-100/cyclohexane compared to [C2mim][C6SO4]/TX-100/cyclohexane and [C2mim][C8SO4

  2. Cistus ladanifer L. Shrub is Rich in Saturated and Branched Chain Fatty Acids and their Concentration Increases in the Mediterranean Dry Season.

    PubMed

    Guerreiro, Olinda; Alves, Susana P; Duarte, Maria F; Bessa, Rui J B; Jerónimo, Eliana

    2015-05-01

    The Cistus ladanifer L. shrub is a widespread species of the Mediterranean region that is available as a feed source for ruminants all the year round, constituting a source of energy and nutrients when most of the vegetation is dry. However, there is no trustworthy information about the fatty acid composition of C. ladanifer, as well as no information about the seasonal and age related changes in their fatty acid composition. Thus, we collected the aerial parts of C. ladanifer plants of two age groups [young vs. older ones (2-6 years old)] during four consecutive seasons to characterize their fatty acid composition. The fatty acid composition of C. ladanifer is dominated by saturated fatty acids including the occurrence of two methyl branched chain fatty acids (BCFA), the iso-19:0 and iso-21:0, which as far as we know were detected for the first time in shrubs. Also, we demonstrated that several labdane type compounds might interfere with the fatty acid analysis of C. ladanifer. Marked seasonal changes in BCFA and polyunsaturated fatty acids (PUFA) were found, suggesting that BCFA can replace PUFA in plant lipids at high environmental temperatures.

  3. 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.

  4. Targeted metabolomic analysis reveals the association between the postprandial change in palmitic acid, branched-chain amino acids and insulin resistance in young obese subjects.

    PubMed

    Liu, Liyan; Feng, Rennan; Guo, Fuchuan; Li, Ying; Jiao, Jundong; Sun, Changhao

    2015-04-01

    Obesity is the result of a positive energy balance and often leads to difficulties in maintaining normal postprandial metabolism. The changes in postprandial metabolites after an oral glucose tolerance test (OGTT) in young obese Chinese men are unclear. In this work, the aim is to investigate the complex metabolic alterations in obesity provoked by an OGTT using targeted metabolomics. We used gas chromatography-mass spectrometry and ultra high performance liquid chromatography-triple quadrupole mass spectrometry to analyze serum fatty acids, amino acids and biogenic amines profiles from 15 control and 15 obese subjects at 0, 30, 60, 90 and 120 min during an OGTT. Metabolite profiles from 30 obese subjects as independent samples were detected in order to validate the change of metabolites. There were the decreased levels of fatty acid, amino acids and biogenic amines after OGTT in obesity. At 120 min, percent change of 20 metabolites in obesity has statistical significance when comparing with the controls. The obese parameters was positively associated with changes in arginine and histidine (P<0.05) and the postprandial change in palmitic acid (PA), branched-chain amino acids (BCAAs) and phenylalanine between 1 and 120 min were positively associated with fasting insulin and HOMA-IR (all P<0.05) in the obese group. The postprandial metabolite of PA and BCAAs may play important role in the development and onset of insulin resistance in obesity. Our findings offer new insights in the complex physiological regulation of the metabolism during an OGTT in obesity.

  5. The development and application of a single-cell biosensor for the detection of l-methionine and branched-chain amino acids.

    PubMed

    Mustafi, Nurije; Grünberger, Alexander; Kohlheyer, Dietrich; Bott, Michael; Frunzke, Julia

    2012-07-01

    The detection and quantification of specific metabolites in single bacterial cells is a major goal for industrial biotechnology. We have developed a biosensor based on the transcriptional regulator Lrp that detects intracellular l-methionine and branched-chain amino acids in Corynebacterium glutamicum. In assays, fluorescence output showed a linear relationship with cytoplasmic concentrations of the effector amino acids. In increasing order, the affinity of Lrp for the amino acids is l-valine, l-isoleucine, l-leucine and l-methionine. The sensor was applied for online monitoring and analysis of cell-to-cell variability of l-valine production by the pyruvate dehydrogenase-deficient C. glutamicum strain ΔaceE. Finally, the sensor system was successfully used in a high-throughput (HT) FACS screen for the isolation of amino acid-producing mutants after random mutagenesis of a non-producing wild type strain. These applications illustrate how one of nature's sensor devices - transcriptional regulators - can be used for the analysis, directed evolution and HT screening for microbial strain development.

  6. Oxidation of aliphatic, branched chain, and aromatic hydrocarbons by Nocardia cyriacigeorgica isolated from oil-polluted sand samples collected in the Saudi Arabian Desert.

    PubMed

    Le, Thi Nhi-Cong; Mikolasch, Annett; Awe, Susanne; Sheikhany, Halah; Klenk, Hans-Peter; Schauer, Frieder

    2010-06-01

    A soil bacterium isolated from oil-polluted sand samples collected in the Saudi Arabian Desert has been determined as Nocardia cyriacigeorgica, which has a high capacity of degrading and utilizing a broad range of hydrocarbons. The metabolic pathways of three classes of hydrocarbons were elucidated by identifying metabolites in cell-free extracts analyzed by GC/MS and HPLC/UV-Vis in comparison with standard compounds. During tetradecane oxidation, tetradecanol; tetradecanoic acid; dodecanoic acid; decanoic acid could be found as metabolites, indicating a monoterminal degradation pathway of n -alkanes. The oxidation of pristane resulted in the presence of pristanoic acid; 2-methylglutaric acid; 4,8-dimethylnonanoic acid; and 2,6-dimethylheptanoic acid, which give rise to a possible mono- and di-terminal oxidation. In case of sec -octylbenzene, eight metabolites were detected including 5-phenylhexanoic acid; 3-phenylbutyric acid; 2-phenylpropionic acid; beta -methylcinnamic acid; acetophenone; beta -hydroxy acetophenone; 2,3-dihydroxy benzoic acid and succinic acid. From these intermediates a new degradation pathway for sec -octylbenzene was investigated. Our results indicate that N. cyriacigeorgica has the ability to degrade aliphatic and branched chain alkanes as well as alkylbenzene effectively and, therefore, N. cyriacigeorgica is probably a suitable bacterium for biodegradation of oil or petroleum products in contaminated soils.

  7. Effects of Diets Supplemented with Branched-Chain Amino Acids on the Performance and Fatigue Mechanisms of Rats Submitted to Prolonged Physical Exercise

    PubMed Central

    Falavigna, Gina; Junior, Jonas Alves de Araújo; Rogero, Marcelo Macedo; Pires, Ivanir Santana de Oliveira; Pedrosa, Rogério Graça; Junior, Eivor Martins; de Castro, Inar Alves; Tirapegui, Julio

    2012-01-01

    This study aimed to determine the effects of diets chronically supplemented with branched-chain amino acids (BCAA) on the fatigue mechanisms of trained rats. Thirty-six adult Wistar rats were trained for six weeks. The training protocol consisted of bouts of swimming exercise (one hour a day, five times a week, for six weeks). The animals received a control diet (C) (n = 12), a diet supplemented with 3.57% BCAA (S1) (n = 12), or a diet supplemented with 4.76% BCAA (S2) (n = 12). On the last day of the training protocol, half the animals in each group were sacrificed after one hour of swimming (1H), and the other half after a swimming exhaustion test (EX). Swimming time until exhaustion was increased by 37% in group S1 and reduced by 43% in group S2 compared to group C. Results indicate that the S1 diet had a beneficial effect on performance by sparing glycogen in the soleus muscle (p < 0.05) and by inducing a lower concentration of plasma ammonia, whereas the S2 diet had a negative effect on performance due to hyperammonemia (p < 0.05). The hypothalamic concentration of serotonin was not significantly different between the 1H and EX conditions. In conclusion, chronic BCAA supplementation led to increased performance in rats subjected to a swimming test to exhaustion. However, this is a dose-dependent effect, since chronic ingestion of elevated quantities of BCAA led to a reduction in performance. PMID:23201847

  8. 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

  9. Selective increases of extracellular brain concentrations of aromatic and branched-chain amino acids in relation to deterioration of neurological status in acute (ischemic) liver failure.

    PubMed

    Michalak, A; Butterworth, R F

    1997-12-01

    Previous reports based on studies in brain tissue from humans and experimental animals suggest that aromatic amino acids (AAAs) and branched-chain amino acids (BCAA's) accumulate in brain in acute liver failure. In order to assess these changes in relation to the severity of neurological impairment and to the degree of hyperammonemia, AAAs and BCAAs were measured in vivo by cerebral microdialysis in frontal cortex of rats at various stages during the development of hepatic encephalopathy due to acute liver failure resulting from portacaval anastomosis followed by hepatic artery ligation. Extracellular brain concentrations of AAAs and of valine and leucine were elevated 2 to 4-fold following hepatic devascularization and these increases were significantly correlated to arterial ammonia concentration (r= 0.71-0.84, p<0.05). Extracellular concentrations of tyrosine paralleled the deterioration of neurological status in acute liver failure rats. In view of their role as precursors of monoamine neurotransmitters, ammonia-induced alterations of intracellular/extracellular brain concentration ratios for AAAs could account for altered neuronal excitability and contribute to the encephalopathy characteristic of acute liver failure.

  10. 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.

  11. Branched-Chain Amino Acid Plus Glucose Supplement Reduces Exercise-Induced Delayed Onset Muscle Soreness in College-Age Females

    PubMed Central

    Leahy, Danielle T.; Pintauro, Stephen J.

    2013-01-01

    Supplementation with branched-chain amino acids (BCAAs) has been used to stimulate muscle protein synthesis following exercise. The purpose of this study was to determine if supplementation with BCAAs in combination with glucose would reduce exercise-induced delayed onset muscle soreness (DOMS). Using a double-blind crossover design, 20 subjects (11 females, 9 males) were randomly assigned to either BCAA (n = 10) or placebo (n = 10) groups. Subjects performed a squatting exercise to elicit DOMS and rated their muscle soreness every 24 hours for four days following exercise while continuing to consume the BCAA or placebo. Following a three-week recovery period, subjects returned and received the alternate BCAA or placebo treatment, repeating the same exercise and DOMS rating protocol for the next four days. BCAA supplementation in female subjects resulted in a significant decrease in DOMS versus placebo at 24 hours following exercise (P = 0.018). No significant effect of BCAA supplementation versus placebo was noted in male subjects nor when male and female results were analyzed together. This gender difference may be related to dose per body weight differences between male and female subjects. PMID:24967261

  12. High incidence of lipid deposition in the liver of rats fed a diet supplemented with branched-chain amino acids under vitamin B6 deficiency.

    PubMed

    Kaimoto, Tae; Shibuya, Mayumi; Nishikawa, Kazutaka; Maeda, Hideo

    2013-01-01

    Male Wistar rats were fed four diets composed of purified 20% vitamin-free casein diet with (+) or without (-) vitamin B(6) (7.0 mg of pyridoxine HCl/kg of diet) and with (+) or without (-) branched-chain amino acids (BCAAs) of valine, leucine, and isoleucine (4.75%): B(6)(+)BCAA(-); B(6)(+)BCAA(+); B(6)(-)BCAA(-); and B(6)(-)BCAA(+) for 21 d. Among rats fed the B(6)(-)BCAA(+) diet, about a half showed lipid deposition in the liver. On the other hand, serum triacylglycerol levels in the B(6)(-)BCAA(+) group tended to be decreased. Hepatic triacylglycerol and cholesterol levels tended to increase in the B(6)(-)BCAA(+) group compared with the other three groups. Serum apolipoprotein B and apolipoprotein E (apo E) levels in the B(6)(-)BCAA(+) group were the lowest among the three groups. In contrast, hepatic apo E levels in the B(6)(-)BCAA(+) group were the highest among the three groups. High-performance liquid chromatography of pooled serum of rats with lipid deposits revealed that triacylglycerol and cholesterol levels in very low-density lipoprotein (VLDL) were decreased compared with other diet groups. These results strongly suggest that one of the mechanisms of lipid deposition in rats fed a B(6)(-)BCAA(+) diet is due to impaired secretion of VLDL.

  13. Complete amino acid sequence of branched-chain amino acid aminotransferase (transaminase B) of Salmonella typhimurium, identification of the coenzyme-binding site and sequence comparison analysis

    SciTech Connect

    Feild, M.J.

    1988-01-01

    The complete amino acid sequence of the subunit of branched-chain amino acid aminotransferase of Salmonella typhimurium was determined by automated Edman degradation of peptide fragments generated by chemical and enzymatic digestion of S-carboxymethylated and S-pyridylethylated transaminase B. Peptide fragments of transaminase B were generated by treatment of the enzyme with trypsin, Staphylococcus aureus V8 protease, endoproteinase Lys-C, and cyanogen bromide. Protocols were developed for separation of the peptide fragments by reverse-phase high performance liquid chromatography (HPLC), ion-exchange HPLC, and SDS-urea gel electrophoresis. The enzyme subunit contains 308 amino acid residues and has a molecular weight of 33,920 daltons. The coenzyme-binding site was determined by treatment of the enzyme, containing bound pyridoxal 5-phosphate, with tritiated sodium borohydride prior to trypsin digestion. Monitoring radioactivity incorporation and peptide map comparisons with an apoenzyme tryptic digest, allowed identification of the pyridoxylated-peptide which was isolated by reverse-phase HPLC and sequenced. The coenzyme-binding site is a lysyl residue at position 159. Some peptides were further characterized by fast atom bombardment mass spectrometry.

  14. 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.

  15. Partial deficiency of isoleucine impairs root development and alters transcript levels of the genes involved in branched-chain amino acid and glucosinolate metabolism in Arabidopsis.

    PubMed

    Yu, Hailan; Zhang, Fengxia; Wang, Guodong; Liu, Yule; Liu, Dong

    2013-01-01

    Isoleucine is one of the branched-chain amino acids (BCAAs) that are essential substrates for protein synthesis in all organisms. Although the metabolic pathway for isoleucine has been well characterized in higher plants, it is not known whether it plays a specific role in plant development. In this study, an Arabidopsis mutant, lib (low isoleucine biosynthesis), that has defects in both cell proliferation and cell expansion processes during root development, was characterized. The lib mutant carries a T-DNA insertion in the last exon of the OMR1 gene that encodes a threonine deaminase/dehydratase (TD). TD catalyses the deamination and dehydration of threonine, which is the first and also the committed step in the biosynthesis of isoleucine. This T-DNA insertion results in a partial deficiency of isoleucine in lib root tissues but it does not affect its total protein content. Application of exogenous isoleucine or introduction of a wild-type OMR1 gene into the lib mutant can completely rescue the mutant phenotypes. These results reveal an important role for isoleucine in plant development. In addition, microarray analysis indicated that the partial deficiency of isoleucine in the lib mutant triggers a decrease in transcript levels of the genes encoding the major enzymes involved in the BCAA degradation pathway; the analysis also indicated that many genes involved in the biosynthesis of methionine-derived glucosinolates are up-regulated.

  16. Protective effects of branched-chain amino acids on hepatic ischemia-reperfusion-induced liver injury in rats: a direct attenuation of Kupffer cell activation.

    PubMed

    Kitagawa, Tomomi; Yokoyama, Yukihiro; Kokuryo, Toshio; Nagino, Masato

    2013-02-15

    We determined whether there is a protective effect of branched-chain amino acid (BCAA) on hepatic ischemia-reperfusion (I/R)-induced acute liver injury. Wister rats were divided into the following four groups: simple laparotomy with vehicle; simple laparotomy with BCAA (1 g/kg body wt orally); I/R (30 min clamp) with vehicle; and I/R with BCAA. Serum liver function tests and the gene expression of adhesion molecules (intercellular adhesion molecule and vascular cell adhesion molecule) and vasoconstrictor-related genes (endothelin-1) in the liver were examined. In the in vivo study, portal venous pressure, leukocyte adhesion, and hepatic microcirculation were evaluated. Furthermore, Kupffer cells were isolated and cultured with various concentrations of BCAA in the presence or absence of lipopolysaccharide (LPS). Increased levels of liver function tests following I/R were significantly attenuated by BCAA treatment. The increased expression of adhesion molecules and endothelin-1 was also significantly attenuated by BCAA treatment. Moreover, increased portal venous pressure, enhanced leukocyte adhesion, and deteriorated hepatic microcirculation following I/R were all improved by BCAA treatment. In the experiment using isolated Kupffer cells, the expression of interleukin-6, interleukin-1β, and endothelin-1 in response to LPS stimulation was attenuated by BCAA in a dose-dependent fashion. These results indicate that perioperative oral administration of BCAA has excellent therapeutic potential to reduce I/R-induced liver injury. These beneficial effects may result from the direct attenuation of Kupffer cell activation under stressful conditions.

  17. The effect of increased branched-chain amino acid transaminase activity in yeast on the production of higher alcohols and on the flavour profiles of wine and distillates.

    PubMed

    Lilly, Mariska; Bauer, Florian F; Styger, Gustav; Lambrechts, Marius G; Pretorius, Isak S

    2006-08-01

    In Saccharomyces cerevisiae, branched-chain amino acid transaminases (BCAATases) are encoded by the BAT1 and BAT2 genes. BCAATases catalyse the transfer of amino groups between those amino acids and alpha-keto-acids. alpha-Keto-acids are precursors for the biosynthesis of higher alcohols, which significantly influence the aroma and flavour of yeast-derived fermentation products. The objective of this study was to investigate the influence of BAT-gene expression on general yeast physiology, on aroma and flavour compound formation and on the sensory characteristics of wines and distillates. For this purpose, the genes were overexpressed and deleted in a laboratory strain, BY4742, and overexpressed in an industrial wine yeast strain, VIN13. The data show that, with the exception of a slow growth phenotype observed for the BAT1 deletion strain, the fermentation behaviour of the strains was unaffected by the modifications. The chemical and sensory analysis of fermentation products revealed a strong correction between BAT gene expression and the formation of many aroma compounds. The data suggest that the adjustment of BAT gene expression could play an important role in assisting winemakers in their endeavour to produce wines with specific flavour profiles.

  18. 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

  19. Synthetic high-charge organomica: effect of the layer charge and alkyl chain length on the structure of the adsorbed surfactants.

    PubMed

    Pazos, M Carolina; Castro, Miguel A; Orta, M Mar; Pavón, Esperanza; Valencia Rios, Jesús S; Alba, María D

    2012-05-15

    A family of organomicas was synthesized using synthetic swelling micas with high layer charge (Na(n)Si(8-n)Al(n)Mg(6)F(4)O(20)·XH(2)O, where n = 2, 3, and 4) exchanged with dodecylammonium and octadecylammonium cations. The molecular arrangement of the surfactant was elucidated on the basis on XRD patterns and DTA. The ordering conformation of the surfactant molecules into the interlayer space of micas was investigated by (13)C, (27)Al, and (29)Si MAS NMR. The arrangement of alkylammonium ions in these high-charge synthetic micas depends on the combined effects of the layer charge of the mica and the chain length of the cation. In the organomicas with dodecylammonium, a transition from a parallel layer to a bilayer-paraffin arrangement is observed when the layer charge of the mica increases. However, when octadecylammonium is the interlayer cation, the molecular arrangement of the surfactant was found to follow the bilayer-paraffin model for all values of layer charge. The amount of ordered conformation all-trans is directly proportional of layer charge.

  20. Alkyl ferulates in wound healing potato tubers.

    PubMed

    Bernards, M A; Lewis, N G

    1992-10-01

    Seven ferulic acid esters of 1-alkanols ranging in carbon length from C16 to C28 were synthesized and an HPLC protocol for their separation developed. Extracts prepared from wound healing potato (Solanum tuberosum) tubers and analysed by HPLC indicated that alkyl ferulate esters begin to accumulate 3-7 days after wound treatment. Of the nine esters identified by EIMS, (including two esters of odd chain length alkanols) hexadecyl and octadecyl ferulates were predominant. Alkyl ferulate esters were restricted to the wound periderm.

  1. 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

  2. Altered kinetic properties of the branched-chain alpha-keto acid dehydrogenase complex due to mutation of the beta-subunit of the branched-chain alpha-keto acid decarboxylase (E1) component in lymphoblastoid cells derived from patients with maple syrup urine disease.

    PubMed Central

    Indo, Y; Kitano, A; Endo, F; Akaboshi, I; Matsuda, I

    1987-01-01

    Branched-chain alpha-keto acid dehydrogenase (BCKDH) complexes of lymphoblastoid cell lines derived from patients with classical maple syrup urine disease (MSUD) phenotypes were studied in terms of their catalytic functions and analyzed by immunoblotting, using affinity purified anti-bovine BCKDH antibody. Kinetic studies on three cell lines derived from patients with the classical phenotype showed sigmoidal or near sigmoidal kinetics for overall BCKDH activity and a deficiency of the E1 component activity. An immunoblot study revealed a markedly decreased amount of the E1 beta subunit accompanied by weak staining of the E1 alpha subunit. The E2 and E3 component exhibited a cross-reactive peptide. Thus, in at least some patients with MSUD, mutations of the E1 beta subunit might provide an explanation for the altered kinetic properties of the BCKDH complex. Images PMID:3597778

  3. Biodiesel production from triolein and short chain alcohols through biocatalysis.

    PubMed

    Salis, Andrea; Pinna, Marcella; Monduzzi, Maura; Solinas, Vincenzo

    2005-09-29

    Oleic acid alkyl esters (biodiesel) were synthesised by biocatalysis in solvent-free conditions. Different commercial immobilised lipases, namely Candida antarctica B, Rizhomucor miehei, and Pseudomonas cepacia, were tested towards the reaction between triolein and butanol to produce butyl oleate. Pseudomonas cepacia lipase resulted to be the most active enzyme reaching 100% of conversion after 6h. Different operative conditions such as reaction temperature, water activity, and reagent stoichiometric ratio were investigated and optimised. These conditions were then used to investigate the effect of linear and branched short chain alcohols. Methanol and 2-butanol were the worst alcohols: the former, probably, due to its low miscibility with the oil and the latter because secondary alcohols usually are less reactive than primary alcohols. Conversely, linear and branched primary alcohols with short alkyl chains (C(2)--C(4)) showed high reaction rate and conversion. A mixture of linear and branched short chain alcohols that mimics the residual of ethanol distillation (fusel oil) was successfully used for oleic acid ester synthesis. These compounds are important in biodiesel mixtures since they improve low temperature properties.

  4. Ab initio study of key branching reactions in biodiesel and Fischer-Tropsch fuels.

    PubMed

    Davis, Alexander C; Francisco, Joseph S

    2011-11-30

    Many biologically and Fischer-Tropsch synthesized fuels contain branched alkanes which, during their combustion and atmospheric oxidation mechanism, produce methylalkyl radicals. As a result, an accurate description of the chemistry of these species is essential to integrating these fuels into our energy systems. Even though branched alkanes make up roughly one-third of the compounds in gasoline and diesel fuels, both experimental and theoretical data on methylalkyl radicals and their reactions are scarce, especially for larger chain systems and combustion conditions. The present work investigates all the hydrogen migration reactions available to the n-methylprop-1-yl through n-methylhept-1-yl radicals, for n = 2-6, using the CBS-Q, G2, and G4 composite computational methods, over a wide temperature range. The resulting thermodynamic and kinetic parameters are used to determine the effect that the presence of the methyl group has on these important unimolecular, chain branching reactions, for the reactions involving not only a tertiary abstraction site but also all the primary and secondary sites. The activation energies of hydrogen migration reactions with the methyl group, either within or immediately outside the ring, are found to be roughly 0.8-1.6 kcal mol(-1) lower in energy than expected on the basis of analogous reactions in n-alkyl radicals. An important implication of this result is that the current method of using rate parameters derived from n-alkyl radicals to predict the chain branching characteristics of methylated alkyl radicals significantly underpredicts the importance of these reactions in atmospheric and combustion processes. Discussion of a possible cause for this phenomenon and its effect on the overall combustion mechanism of branched hydrocarbons is presented. Of particular concern is that 2,2,4,4,6,8,8-heptamethylnonane, which is currently used to model branched alkanes in diesel fuel surrogates, is predicted to have a much lower activation

  5. 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.

  6. 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.

  7. 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.

  8. Branched-chain amino acid supplements reduced ascites and increased the quality of life in a patient with liver cirrhosis: A case report.

    PubMed

    Itou, Minoru; Kawaguchi, Takumi; Taniguchi, Eitaro; Oku, Yuichiro; Fukushima, Nobuyoshi; Ando, Eiji; Oriishi, Tetsuharu; Uchida, Yuki; Otsuka, Momoka; Tanaka, Suiko; Iwasaki, Shoko; Torii, Mari; Yoshida, Kiyomi; Adachi, Yuko; Suga, Mariko; Yoshiyama, Manami; Ibi, Ryoko; Akiyama, Yoshiko; Takakura, Machiko; Mitsuyama, Keiichi; Tsuruta, Osamu; Sata, Michio

    2009-01-01

    Liver cirrhosis is frequently accompanied by malnutrition and hypoalbuminemia, which in turn commonly induces ascites in patients with liver cirrhosis. Ascites leads to abdominal distention and appetite loss, resulting in a deteriorated quality of life (QOL). Administration of branched-chain amino acid (BCAA)-rich supplements reduces hepatic encephalopathy and malnutrition. In addition, BCAAs by themselves up-regulate albumin synthesis through an increase in Fisher's ratio. Thus, in patients with liver cirrhosis, BCAA-rich supplements seem to be effective at reducing ascites and improving the QOL. Here, we report the case of a 58-year-old Japanese man with liver cirrhosis with severe ascites and peripheral edema. The hepatic function of the patient was classified as Child-Pugh grade C. To reduce protein-energy malnutrition, BCAA-rich supplements were administered as a late evening snack as part of a regimen including 2000 kcal/day (32.5 kcal/kg/day) of total energy and 83.5 g/day (1.3 g/kg/day) of total protein intake. Eight weeks after admission, ascites and edema had decreased. Nutritional status also improved from the time of admission to discharge; the serum BCAA level increased from 365.4 to 450.2 µmol/l. Furthermore, the ratio of BCAAs to tyrosine (BTR) increased from 1.70 to 3.65. We also evaluated the effects of nutritional therapy on the patient's QOL using the Medical Outcomes Study 36-Item Short-Form Health Survey upon admission and at discharge. All subscores showed marked improvement and reached a level greater than the Japanese norm with nutritional treatment. In conclusion, BCAA supplementation not only reduced ascites, but also improved the QOL in a patient with liver cirrhosis.

  9. Effects of Combined Treatment with Branched-Chain Amino Acids, Citric Acid, L-Carnitine, Coenzyme Q10, Zinc, and Various Vitamins in Tumor-Bearing Mice.

    PubMed

    Awa, Hiroko; Futamura, Akihiko; Higashiguchi, Takashi; Ito, Akihiro; Mori, Naoharu; Murai, Miyo; Ohara, Hiroshi; Chihara, Takeshi; Kaneko, Takaaki

    2017-03-01

    A functional dietary supplement (FDS) containing Coenzyme Q10, branched-chain amino acids and L-carnitine was administered to tumor-bearing mice, investigating its effects on tumor and muscle tissues. Experiment (A): B16 melanoma cells were implanted subcutaneously into the right side of the abdomen of 8- to 9-week-old C57BL/6J mice. The mice were divided into two groups: a FDS group that received oral administration of FDS (n=10), and a control group that received oral administration of glucose (n=10). The moribund condition was used as the endpoint, and median survival time was determined. Experiment (B): On day 21 after tumor implantation, tumors, soleus muscle, gastrocnemius muscle, and suprahyoid muscles were collected. Tumor and muscle weight and other aspects were evaluated in each group: FDS group (n=15) and control group (n=15). The median survival time was comparable (21 d in the FDS group vs. 18 d in the control group, p=0.30). However, cumulative food intake was significantly higher in the FDS group than the control group (p=0.011). Metastasis of melanoma to the lung was observed in the control group but not in the FDS group (p=0.043). The weight of the suprahyoid muscles was significantly higher in the FDS group than in the control group (p=0.0045). The weight of the tumor was significantly lower in the FDS group than in the control group (p=0.013). The results possibly suggest oral administration of FDS in tumor-bearing mice enhances the maintenance of suprahyoid muscles, resulting in an extended feeding period and suppression of tumor growth and metastasis.

  10. 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

  11. Combined effect of branched-chain amino acids and taurine supplementation on delayed onset muscle soreness and muscle damage in high-intensity eccentric exercise

    PubMed Central

    2013-01-01

    Background Previous studies have evaluated the effectiveness of branched-chain amino acid (BCAA) supplementation for preventing delayed onset muscle soreness (DOMS) and muscle damage induced by eccentric exercise, their findings have been inconclusive. Since taurine has anti-inflammatory and anti-oxidative effects, the present study investigated the combined effect of BCAA and taurine on DOMS and muscle damage. Methods Thirty-six untrained male subjects (22.5 ± 3.8 years) were assigned to four groups (placebo + placebo [placebo], BCAA + placebo, placebo + taurine, and BCAA + taurine [combined]) and given a combination of 3.2 g BCAA (or placebo) and 2.0 g taurine (or placebo), three times a day, for two weeks prior to and three days after eccentric elbow flexor exercises. DOMS and muscle damage in the biceps brachii were subjectively and objectively evaluated using the visual analogue scale (VAS), upper arm circumference (CIR), and blood parameters (creatine kinase, lactate dehydrogenase [LDH], aldolase, and 8-hydroxydeoxyguanosine [8-OHdG]). Results In the combined group, VAS and 8-OHdG two days after exercise, CIR two and three days after exercise and LDH from one to three days after exercise were significantly lower than the placebo group. The area under the curve from before exercise to four days later for CIR, LDH, and aldolase was also significantly lower in the combined group than in the placebo group. Conclusion A combination of 3.2 g BCAA and 2.0 g taurine, three times a day, for two weeks prior to and three days after exercise may be a useful nutritional strategy for attenuating exercise-induced DOMS and muscle damage. PMID:24195702

  12. Branched-chain amino acids prevent hepatic fibrosis and development of hepatocellular carcinoma in a non-alcoholic steatohepatitis mouse model.

    PubMed

    Takegoshi, Kai; Honda, Masao; Okada, Hikari; Takabatake, Riuta; Matsuzawa-Nagata, Naoto; Campbell, Jean S; Nishikawa, Masashi; Shimakami, Tetsuro; Shirasaki, Takayoshi; Sakai, Yoshio; Yamashita, Taro; Takamura, Toshinari; Tanaka, Takuji; Kaneko, Shuichi

    2017-02-13

    Oral supplementation with branched-chain amino acids (BCAA; leucine, isoleucine, and valine) in patients with liver cirrhosis potentially suppresses the incidence of hepatocellular carcinoma (HCC) and improves event-free survival. However, the detailed mechanisms of BCAA action have not been fully elucidated. BCAA were administered to atherogenic and high-fat (Ath+HF) diet-induced nonalcoholic steatohepatitis (NASH) model mice. Liver histology, tumor incidence, and gene expression profiles were evaluated. Ath+HF diet mice developed hepatic tumors at a high frequency at 68 weeks. BCAA supplementation significantly improved hepatic steatosis, inflammation, fibrosis, and tumors in Ath+HF mice at 68 weeks. GeneChip analysis demonstrated the significant resolution of pro-fibrotic gene expression by BCAA supplementation. The anti-fibrotic effect of BCAA was confirmed further using platelet-derived growth factor C transgenic mice, which develop hepatic fibrosis and tumors. In vitro, BCAA restored the transforming growth factor (TGF)-β1-stimulated expression of pro-fibrotic genes in hepatic stellate cells (HSC). In hepatocytes, BCAA restored TGF-β1-induced apoptosis, lipogenesis, and Wnt/β-Catenin signaling, and inhibited the transformation of WB-F344 rat liver epithelial stem-like cells. BCAA repressed the promoter activity of TGFβ1R1 by inhibiting the expression of the transcription factor NFY and histone acetyltransferase p300. Interestingly, the inhibitory effect of BCAA on TGF-β1 signaling was mTORC1 activity-dependent, suggesting the presence of negative feedback regulation from mTORC1 to TGF-β1 signaling. Thus, BCAA induce an anti-fibrotic effect in HSC, prevent apoptosis in hepatocytes, and decrease the incidence of HCC; therefore, BCAA supplementation would be beneficial for patients with advanced liver fibrosis with a high risk of HCC.

  13. 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

  14. Insulin does not stimulate muscle protein synthesis during increased plasma branched-chain amino acids alone but still decreases whole body proteolysis in humans.

    PubMed

    Everman, Sarah; Meyer, Christian; Tran, Lee; Hoffman, Nyssa; Carroll, Chad C; Dedmon, William L; Katsanos, Christos S

    2016-10-01

    Insulin stimulates muscle protein synthesis when the levels of total amino acids, or at least the essential amino acids, are at or above their postabsorptive concentrations. Among the essential amino acids, branched-chain amino acids (BCAA) have the primary role in stimulating muscle protein synthesis and are commonly sought alone to stimulate muscle protein synthesis in humans. Fourteen healthy young subjects were studied before and after insulin infusion to examine whether insulin stimulates muscle protein synthesis in relation to the availability of BCAA alone. One half of the subjects were studied in the presence of postabsorptive BCAA concentrations (control) and the other half in the presence of increased plasma BCAA (BCAA). Compared with that prior to the initiation of the insulin infusion, fractional synthesis rate of muscle protein (%/h) did not change (P > 0.05) during insulin in either the control (0.04 ± 0.01 vs 0.05 ± 0.01) or the BCAA (0.05 ± 0.02 vs. 0.05 ± 0.01) experiments. Insulin decreased (P < 0.01) whole body phenylalanine rate of appearance (μmol·kg(-1)·min(-1)), indicating suppression of muscle proteolysis, in both the control (1.02 ± 0.04 vs 0.76 ± 0.04) and the BCAA (0.89 ± 0.07 vs 0.61 ± 0.03) experiments, but the change was not different between the two experiments (P > 0.05). In conclusion, insulin does not stimulate muscle protein synthesis in the presence of increased circulating levels of plasma BCAA alone. Insulin's suppressive effect on proteolysis is observed independently of the levels of circulating plasma BCAA.

  15. Thiamin-responsive maple-syrup-urine disease: decreased affinity of the mutant branched-chain alpha-keto acid dehydrogenase for alpha-ketoisovalerate and thiamin pyrophosphate.

    PubMed Central

    Chuang, D T; Ku, L S; Cox, R P

    1982-01-01

    The biochemical basis for the therapeutic effects of thiamin in thiamin-responsive maple-syrup-urine disease (MSUD) was investigated in intact and disrupted fibroblast cultures from normals and patients with various forms of MSUD. Decarboxylation of alpha-keto[1-14C]isovalerate (KIV) by intact cells from a thiamin-responsive MSUD patient was at 30-40% of the normal rate with or without thiamin in the incubation medium. Under similar conditions, intact classical MSUD fibroblasts failed to decarboxylate KIV. Branched-chain alpha-keto acid (BCKA) dehydrogenase activity measured in disrupted cells from the thiamin-responsive subject showed sigmoidal kinetics in the absence of thiamin pyrophosphate (TPP), with an increased concentration of substrate needed for half-maximal velocity (K0.5 for KIV = 7 mM vs. 0.05 mM in normal cells). When assayed with 0.2 mM TPP present, the mutant enzyme showed (i) a shift in kinetics to near Michaelis-Menten type as observed with the normal BCKA dehydrogenase and (ii) a lower K0.5 value of 4 mM for KIV, suggesting a TPP-mediated increase in the mutant enzyme's affinity for substrate. By contrast, TPP increased only the Vmax and was without effect on the apparent Km for KIV of the BCKA dehydrogenase from cells of normals and patients with classical MSUD and variant thiamin-responsive MSUD (grade 3). Measurement of the apparent Km for TPP of the BCKA dehydrogenase from thiamin-responsive mutant MSUd cells showed a 16-fold increase in the constant to 25 microM compared to enzymes from normal or classical MSUD cells. These findings demonstrate that the primary defect in the thiamin-responsive MSUD patient is a reduced affinity of the mutant BCKA dehydrogenase for TPP that results in impaired oxidative decarboxylation of BCKA. PMID:6954481

  16. Preventive effects of branched-chain amino acid supplementation on the spontaneous development of hepatic preneoplastic lesions in C57BL/KsJ-db/db obese mice.

    PubMed

    Terakura, Daishi; Shimizu, Masahito; Iwasa, Junpei; Baba, Atsushi; Kochi, Takahiro; Ohno, Tomohiko; Kubota, Masaya; Shirakami, Yohei; Shiraki, Makoto; Takai, Koji; Tsurumi, Hisashi; Tanaka, Takuji; Moriwaki, Hisataka

    2012-12-01

    Obesity and its associated disorders, such as non-alcoholic steatohepatitis, increase the risk of hepatocellular carcinoma. Branched-chain amino acids (BCAA), which improve protein malnutrition in patients with liver cirrhosis, reduce the risk of hepatocellular carcinoma in these patients with obesity. In the present study, the effects of BCAA supplementation on the spontaneous development of hepatic premalignant lesions, foci of cellular alteration, in db/db obese mice were examined. Male db/db mice were given a basal diet containing 3.0% of either BCAA or casein, a nitrogen-content-matched control of BCAA, for 36 weeks. On killing the mice, supplementation with BCAA significantly inhibited the development of foci of cellular alteration when compared with casein supplementation by inhibiting cell proliferation, but inducing apoptosis. BCAA supplementation increased the expression levels of peroxisome proliferator-activated receptor-γ, p21(CIP1) and p27(KIP1) messenger RNA and decreased the levels of c-fos and cyclin D1 mRNA in the liver. BCAA supplementation also reduced both the amount of hepatic triglyceride accumulation and the expression of interleukin (IL)-6, IL-1β, IL-18 and tumor necrosis factor-α mRNA in the liver. Increased macrophage infiltration was inhibited and the expression of IL-6, TNF-α, and monocyte chemoattractant protein-1 mRNA in the white adipose tissue were each decreased by BCAA supplementation. BCAA supplementation also reduced adipocyte size while increasing the expression of peroxisome proliferator-activated receptor-α, peroxisome proliferator-activated receptor-γ and adiponectin mRNA in the white adipose tissue compared with casein supplementation. These findings indicate that BCAA supplementation inhibits the early phase of obesity-related liver tumorigenesis by attenuating chronic inflammation in both the liver and white adipose tissue. BCAA supplementation may be useful in the chemoprevention of liver tumorigenesis in obese

  17. 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.

  18. Chain Sampling

    DTIC Science & Technology

    1972-08-01

    35609 Advanced Techniques Branch Plans and Programs Analysis Division Directorate for Product Assurance U. S. Army Missile Command Redstone Arsenal...Ray Heathcock Advanced Techniques Branch Plans and Programs Analysis Division Directorate for Product Assurance U. S. Army Missile Command...for Product Assurance has established a rather unique computer program for handling a variety of chain sampling schemes and is available for

  19. Heating improves poor compliance with branched chain amino acid-rich supplementation in patients with liver cirrhosis: A before-after pilot study.

    PubMed

    Itou, Minoru; Kawaguchi, Takumi; Taniguchi, Eitaro; Shiraishi, Satomi; Ibi, Ryoko; Mutou, Michiko; Okada, Teruyo; Uchida, Yuki; Otsuka, Momoka; Oriishi, Tetsuharu; Tanaka, Suiko; Takakura, Machiko; Mitsuyama, Keiichi; Tsuruta, Osamu; Sata, Michio

    2009-01-01

    Although branched chain amino acid (BCAA) supplementation improves malnutrition in cirrhotic patients, patient compliance with the administration of BCAA-rich supplements is poor due to their bitter taste. Since temperature is an important factor affecting taste, we examined the effect of heating on the stability of BCAAs and on the compliance of patients with liver cirrhosis with BCAA-rich supplement administration. A thermal denaturation test was first conducted, in which the BCAA-rich supplement Aminoleban® EN was heated to 37, 60, or 80°C for 30 or 60 min. The concentration of three amino acids, L-valine, L-leucine and L-isoleucine, was subsequently measured. The nutritional status of the cirrhotic patients was also evaluted. Patients presenting liver failure with a Child-Pugh class of A (n=2), B (n=2) or C (n=2) were hospitalized at Kurume University Hospital. Six patients with liver cirrhosis (HCV, n=3; HBV, n=1; alcohol, n=2) were enrolled. Venous blood samples were drawn in the morning after a 12-h overnight fast. The BCAA-rich supplement was administered to patients at room temperature (25°C) or heat loaded at 60°C for 10 min, with the temperature maintained above 45°C. Each patient was interviewed by a nationally registered dietitian regarding food consumption and intake of the BCAA-rich supplement immediately after each meal. Nutritional status was evaluated according to serum albumin levels, blood hemoglobin, prothrombin time and total lymphocyte count. No significant decrease was noted in valine, leucine or isoleucine levels following the heating of the BCAAs to 80°C. The caloric intake of the BCAA-rich supplement was significantly higher with administration after heating to 60°C, compared to caloric intake with administration at 25°C. In addition, heating of the BCAA-rich supplement significantly increased blood lymphocyte counts. In conclusion, heating did not affect the stability of the BCAAs, and may improve compliance with BCAA

  20. ALKYL PYROPHOSPHATE METAL SOLVENT EXTRACTANTS AND PROCESS

    DOEpatents

    Long, R.L.

    1958-09-30

    A process is presented for the recovery of uranium from aqueous mineral acidic solutions by solvent extraction. The extractant is a synmmetrical dialkyl pyrophosphate in which the alkyl substituents have a chain length of from 4 to 17 carbon atoms. Mentioned as a preferred extractant is dioctyl pyrophosphate. The uranium is precipitated irom the organic extractant phase with an agent such as HF, fluoride salts. alcohol, or ammonia.

  1. 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.

  2. Synthesis Of Alkyl Hydroperoxides Via Alkylation Of gem-Dihydroperoxides

    PubMed Central

    Kyasa, ShivaKumar; Puffer, Benjamin W.

    2013-01-01

    Two-fold alkylation of 1,1-dihydroperoxides, followed by hydrolysis of the resulting bisperoxyacetals, provides a convenient method for synthesis of primary and secondary alkyl hydroperoxides. PMID:23469994

  3. Both total chain length and position of dimethyl-branching effect the myocardial uptake and retention of radioiodinated analogues of 15-(p-iodophenyl)-3,3-dimethylpentadecanoic acid (DMIPP).

    PubMed

    Knapp, F F; Goodman, M M; Kirsch, G; Reske, S N; Kropp, J; Biersack, H J; Ambrose, K R; Lambert, C R; Goudonnet, A

    1996-02-01

    Introduction of geminal dimethyl-branching into the 3-position of 15-(p-iodophenyl) pentadecanoic acid (IPPA) significantly delays myocardial clearance in rats and dogs following intravenous administration. Several new analogues of DMIPP have been synthesized and evaluated in fasted rats. The effects of both the position of dimethyl-branching and the total chain-length of 3, 3-dimethyl analogues on heart uptake and clearance kinetics have been studied. In the first series of compounds, two methyl groups were introduced into the 3-, 4-, 6-, or 9- position. Tissue distribution studies of the 15-(p-[I-125] iodophenyl)-analogues demonstrated that the position of dimethyl-branching is an important factor affecting both myocardial specificity and retention. The [I-125] labeled 3,3- and 4,4-DMIPP analogues showed higher myocardial uptake and faster blood clearance than the 6,6- and 9,9-DMIPP analogues [heart, % dose/gm heart: blood), 30 min: 3,3-DMIPP = 5.06 (12:1); 4,4-DMIPP = 8.03 (16.7: 1); 6,6-DMIPP = 2.26 (3.1:1); 9,9-DMIPP = 3.06 (2.77)]. In the second series, the effects of total fatty acid chain length were evaluated with 3,3-dimethyl-substituted analogues with C11, C12, C13, C14, C15, and C19 chain lengths. The C14 and C15 chain length analogues showed the best properties [global heart: blood ratios): 30 min: C11, 0.70 (0.82); C12, 1.25 (0.68); C13, 0.47 (0.90); C14, 1.63 (3.54); C15, 5.06 (12); C19. 1.29 (0.82). These detailed studies have demonstrated that both total chain length and the position of geminal dimethyl-branching are important structural parameters which affect myocardial specificity and retention of omega-(p-iodophenyl)-substituted fatty acid analogues and that 3,3-DMIPP and 4,4-DMIPP are the best candidates with optimal properties for further study.

  4. Branched-chain Amino Acids are Beneficial to Maintain Growth Performance and Intestinal Immune-related Function in Weaned Piglets Fed Protein Restricted Diet

    PubMed Central

    Ren, M.; Zhang, S. H.; Zeng, X. F.; Liu, H.; Qiao, S. Y.

    2015-01-01

    As a novel approach for disease control and prevention, nutritional modulation of the intestinal health has been proved. However, It is still unknown whether branched-chain amino acid (BCAA) is needed to maintain intestinal immune-related function. The objective of this study was to determine whether BCAA supplementation in protein restricted diet affects growth performance, intestinal barrier function and modulates post-weaning gut disorders. One hundred and eight weaned piglets (7.96±0.26 kg) were randomly fed one of the three diets including a control diet (21% crude protein [CP], CON), a protein restricted diet (17% CP, PR) and a BCAA diet (BCAA supplementation in the PR diet) for 14 d. The growth performance, plasma amino acid concentrations, small intestinal morphology and intestinal immunoglobulins were tested. First, average daily gain (ADG) (p<0.05) and average daily feed intake (ADFI) (p<0.05) of weaned pigs in PR group were lower, while gain:feed ratio was lower than the CON group (p<0.05). Compared with PR group, BCAA group improved ADG (p<0.05), ADFI (p<0.05) and feed:gain ratio (p<0.05) of piglets. The growth performance data between CON and BCAA groups was not different (p>0.05). The PR and BCAA treatments had a higher (p<0.05) plasma concentration of methionine and threonine than the CON treatment. The level of some essential and functional amino acids (such as arginine, phenylalanine, histidine, glutamine etc.) in plasma of the PR group was lower (p<0.05) than that of the CON group. Compared with CON group, BCAA supplementation significantly increased BCAA concentrations (p<0.01) and decreased urea concentration (p<0.01) in pig plasma indicating that the efficiency of dietary nitrogen utilization was increased. Compared with CON group, the small intestine of piglets fed PR diet showed villous atrophy, increasing of intra-epithelial lymphocytes (IELs) number (p<0.05) and declining of the immunoglobulin concentration, including jejunal

  5. Branched-chain Amino Acids are Beneficial to Maintain Growth Performance and Intestinal Immune-related Function in Weaned Piglets Fed Protein Restricted Diet.

    PubMed

    Ren, M; Zhang, S H; Zeng, X F; Liu, H; Qiao, S Y

    2015-12-01

    As a novel approach for disease control and prevention, nutritional modulation of the intestinal health has been proved. However, It is still unknown whether branched-chain amino acid (BCAA) is needed to maintain intestinal immune-related function. The objective of this study was to determine whether BCAA supplementation in protein restricted diet affects growth performance, intestinal barrier function and modulates post-weaning gut disorders. One hundred and eight weaned piglets (7.96±0.26 kg) were randomly fed one of the three diets including a control diet (21% crude protein [CP], CON), a protein restricted diet (17% CP, PR) and a BCAA diet (BCAA supplementation in the PR diet) for 14 d. The growth performance, plasma amino acid concentrations, small intestinal morphology and intestinal immunoglobulins were tested. First, average daily gain (ADG) (p<0.05) and average daily feed intake (ADFI) (p<0.05) of weaned pigs in PR group were lower, while gain:feed ratio was lower than the CON group (p<0.05). Compared with PR group, BCAA group improved ADG (p<0.05), ADFI (p<0.05) and feed:gain ratio (p<0.05) of piglets. The growth performance data between CON and BCAA groups was not different (p>0.05). The PR and BCAA treatments had a higher (p<0.05) plasma concentration of methionine and threonine than the CON treatment. The level of some essential and functional amino acids (such as arginine, phenylalanine, histidine, glutamine etc.) in plasma of the PR group was lower (p<0.05) than that of the CON group. Compared with CON group, BCAA supplementation significantly increased BCAA concentrations (p<0.01) and decreased urea concentration (p<0.01) in pig plasma indicating that the efficiency of dietary nitrogen utilization was increased. Compared with CON group, the small intestine of piglets fed PR diet showed villous atrophy, increasing of intra-epithelial lymphocytes (IELs) number (p<0.05) and declining of the immunoglobulin concentration, including jejunal

  6. Alkyl and Aromatic Amines as Digestive Ripening/Size Focusing Agents for Gold Nanoparticles

    PubMed Central

    Sun, Yijun; Jose, Deepa; Sorensen, Christopher; Klabunde, Kenneth J.

    2013-01-01

    Both long chain alkyl thiols and alkyl amines behave as size focusing agents for gold nanoparticles, a process that is under thermodynamic control. However, amines do not oxidize surface gold atoms while thiols do oxidize surface gold to gold(I) with evolution of hydrogen gas. Therefore, alkyl amines participate in digestive ripening by a different mechanism. The efficiency of alkyl amines for this process is described and compared, and ultimate gold particle size differences are discussed. Reported herein is a detailed investigation of alkyl chain lengths for alkyl amines, aromatic amines (aniline), and unusually reactive amines (2-phenylethyl amine). Also, two methods of preparation of the crude gold nanoparticles were employed: gold ion reduction/inverse micelle vs. metal vaporization (Solvated Metal Atom Dispersion—SMAD).

  7. Effects of alkyl substituents of xanthine on phosphodiesterase isoenzymes.

    PubMed

    Miyamoto, K; Sakai, R; Kurita, M; Ohmae, S; Sanae, F; Sawanishi, H; Hasegawa, T; Takagi, K

    1995-03-01

    The structure-activity relationships of a series of alkylxanthine derivatives were investigated. The partition coefficient of alkylxanthines enlarged with an elongation of the alkyl chain at the 1-, 3-, or 7-position of xanthine. There was a mild correlation between the apparent partition coefficient and the tracheal relaxant activity or the inhibitory activity on phosphodiesterase (PDE) IV isoenzyme, while the tracheal relaxant activity closely correlated with the PDE IV inhibitory activity. Regarding substituents at different positions, the alkylation at the 3-position increased the inhibitory activity on every PDE isoenzyme. The alkylation at the 1-position potentiated the inhibitory activity on PDE IV with the alkyl chain length, but decreased the activities on other PDE isoenzymes. The alkylation at the 7-position was characteristic in its decrease in inhibitory activity on PDE III. These results suggested that the potency of the inhibitory activity of xanthine derivatives on PDE isoenzymes is not dependent simply upon their hydrophobicity but upon change in the affinity for the active sites on PDE isoenzymes by the introduction of the alkyl group at particular positions of the xanthine skeleton.

  8. Synthesis of branched polysaccharides with tunable degree of branching.

    PubMed

    Ciric, Jelena; Loos, Katja

    2013-03-01

    An in vitro enzyme-catalyzed tandem reaction using the enzymes phosphorylase b from rabbit muscle and Deinococcus geothermalis glycogen branching enzyme (Dg GBE) to obtain branched polyglucans with tunable degree of branching (2% ÷ 13%) is presented. The tunable degree of branching is obtained by varying the reaction conditions such as pH value, the choice of reducing agent and its concentration and reaction time. Linear amylose is formed by the phosphorylase-catalyzed propagation of glucose-1-phosphate while Dg GBE introduces branching points on the α-(1→6) position by relocating short oligosaccharide chains. Our results show that the best way to obtain different degrees of branching with this set of enzymes is by regulation of the reaction time.

  9. Herbicidal action of 2-hydroxy-3-alkyl-1,4-naphthoquinones.

    PubMed

    Jewess, Philip J; Higgins, James; Berry, Kate J; Moss, Stephen R; Boogaard, Adrian B; Khambay, Bhupinder P S

    2002-03-01

    The main mode of herbicidal activity of 2-hydroxy-3-alkyl-1,4-naphthoquinones is shown to be inhibition of photosystem II (PSII). The herbicidal and in vitro activities have been measured and correlated with their (Log)octanol/water partition coefficients (Log Ko/w). The length of the 3-n-alkyl substituent for optimal activity differed between herbicidal and in vitro activity. The maximum in vitro activity was given by the nonyl to dodecyl homologues (Log Ko/w between 6.54 and 8.12), whereas herbicidal activity peaked with the n-hexyl compound (Log Ko/w = 4.95). The effect of chain branching was also investigated using isomeric pentyl analogues substituted at position 3. All exhibited similar levels of in vitro activities but herbicidal activities differed, albeit moderately, with the exception of one analogue that was much less phytotoxic. Other modes of action were also investigated using two representative compounds. They did not show any activity on photosystem I or mitochondrial complex I, or generate toxic oxygen radicals by redox cycling reactions. Only moderate activity was found against mitochondrial complex III from plants, in contrast to much higher corresponding activity using an insect enzyme.

  10. Synthesis and antiviral activity of some C2-, C4-, and C6-substituted pyrazolo[3,4-D]pyrimidine acyclonucleosides with the alkylating chains of ACV, HBG, and ISO-DHPG.

    PubMed

    Moukha-Chafiq, Omar; Taha, Mohamed Labd; Lazrek, Hassan Bihi; Vasseur, Jean-Jacques; Clercq, Erik De

    2006-01-01

    A useful route to obtain trisubstituted pyrazolo[3,4-d]pyrimidines 14-17 is described. Those later were coupled with the alkylating agents 18-20 as in ACV, HBG, and iso-DHPG to give, after deprotection, the desired acylonucleosides 33-44. Almost all of the new compounds were evaluated for their inhibitory effects against the replication of various DNA viruses in culture.

  11. Synthesis and antifungal activity of natural product-based 6-alkyl-2 3 4 5-tetrahydropyridines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven 6-alkyl-2,3,4,5-tetrahydropyridines (5a–5g) that mimic the natural products piperideines that were recently identified in the fire ant venom have been synthesized. Compounds 5c–5g with the C-6 alkyl chain lengths from C14 to C18 showed varying degrees of antifungal activities, with 5e (6-hexa...

  12. Alkyl-π engineering in state control toward versatile optoelectronic soft materials

    PubMed Central

    Lu, Fengniu; Nakanishi, Takashi

    2015-01-01

    Organic π-conjugated molecules with extremely rich and tailorable electronic and optical properties are frequently utilized for the fabrication of optoelectronic devices. To achieve high solubility for facile solution processing and desirable softness for flexible device fabrication, the rigid π units were in most cases attached by alkyl chains through chemical modification. Considerable numbers of alkylated-π molecular systems with versatile applications have been reported. However, a profound understanding of the molecular state control through proper alkyl chain substitution is still highly demanded because effective applications of these molecules are closely related to their physical states. To explore the underlying rule, we review a large number of alkylated-π molecules with emphasis on the interplay of van der Waals interactions (vdW) of the alkyl chains and π–π interactions of the π moieties. Based on our comprehensive investigations of the two interactions’ impacts on the physical states of the molecules, a clear guidance for state control by alkyl-π engineering is proposed. Specifically, either with proper alkyl chain substitution or favorable additives, the vdW and π–π interactions can be adjusted, resulting in modulation of the physical states and optoelectronic properties of the molecules. We believe the strategy summarized here will significantly benefit the alkyl-π chemistry toward wide-spread applications in optoelectronic devices. PMID:27877748

  13. Method of making alkyl esters

    DOEpatents

    Elliott, Brian

    2010-09-14

    Methods of making alkyl esters are described herein. The methods are capable of using raw, unprocessed, low-cost feedstocks and waste grease. Generally, the method involves converting a glyceride source to a fatty acid composition and esterifying the fatty acid composition to make alkyl esters. In an embodiment, a method of making alkyl esters comprises providing a glyceride source. The method further comprises converting the glyceride source to a fatty acid composition comprising free fatty acids and less than about 1% glyceride by mass. Moreover, the method comprises esterifying the fatty acid composition in the presence of a solid acid catalyst at a temperature ranging firm about 70.degree. C. to about 120.degree. C. to produce alkyl esters, such that at least 85% of the free fatty acids are converted to alkyl esters. The method also incorporates the use of packed bed reactors for glyceride conversion and/or fatty acid esterification to make alkyl esters.

  14. A novel type of highly effective nonionic gemini alkyl O-glucoside surfactants: a versatile strategy of design.

    PubMed

    Liu, Songbai; Sang, Ruocheng; Hong, Shan; Cai, Yujing; Wang, Hua

    2013-07-09

    A novel type of highly effective gemini alkyl glucosides has been rationally designed and synthesized. The gemini surfactants have been readily prepared by glycosylation of the gemini alkyl chains that are synthesized with regioselective ring-opening of ethylene glycol epoxides by the alkyl alcohols. The new gemini alkyl glucosides exhibit significantly better surface activity than the known results. Then rheological, DLS, and TEM studies have revealed the intriguing self-assembly behavior of the novel gemini surfactants. This study has proved the effectiveness of the design of gemini alkyl glucosides which is modular, extendable, and synthetically simple. The new gemini surfactants have great potential as nano carriers in drug and gene delivery.

  15. Variation of the Side Chain Branch Position Leads to Vastly Improved Molecular Weight and OPV Performance in 4,8-dialkoxybenzo[1,2-b:4,5-b′]dithiophene/2,1,3-benzothiadiazole Copolymers

    DOE PAGES

    Coffin, Robert C.; MacNeill, Christopher M.; Peterson, Eric D.; ...

    2011-01-01

    Tmore » hrough manipulation of the solubilizing side chains, we were able to dramatically improve the molecular weight ( M w ) of 4,8-dialkoxybenzo[1,2- b :4,5- b ′ ]dithiophene (BDT)/2,1,3-benzothiadiazole (BT) copolymers. When dodecyl side chains ( P1 ) are employed at the 4- and 8-positions of the BDT unit, we obtain a chloroform-soluble copolymer fraction with M w of 6.3 kg/mol. Surprisingly, by moving to the commonly employed 2-ethylhexyl branch ( P2 ), M w decreases to 3.4 kg/mol.his is despite numerous reports that this side chain increases solubility and M w . By moving the ethyl branch in one position relative to the polymer backbone (1-ethylhexyl, P3 ), M w is dramatically increased to 68.8 kg/mol. As a result of this M w increase, the shape of the absorption profile is dramatically altered, with λ max = 637 nm compared with 598 nm for P1 and 579 nm for P2 .he hole mobility as determined by thin film transistor (TFT) measurements is improved from ~ 1 × 10 − 6  cm 2 /Vs for P1 and P2 to 7 × 10 − 4  cm 2 /Vs for P3 , while solar cell power conversion efficiency in increased to 2.91 % for P3 relative to 0.31 % and 0.19 % for P1 and P2 , respectively.« less

  16. Transesterified tyrosol and hydroxytyrosol alkyl esters from cuphea oil – antioxidant behavior in Liposomes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tyrosol and hydroxytyrosol are the antioxidant molecules abundantly found in olive oil. Transesterification of tyrosol and hydroxytyrosol with cuphea oil results in medium