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Sample records for acids leucine valine

  1. Branched-chain amino acid interactions with reference to amino acid requirements in adult men: Valine metabolism at different leucine intakes

    SciTech Connect

    Pelletier, V.; Marks, L.; Wagner, D.A.; Hoerr, R.A.; Young, V.R. )

    1991-08-01

    The authors explored whether the oxidation of valine and by implication the physiological requirement for this amino acid are affected by changes in leucine intake over a physiological range. Six young adult men received, in random order, four L-amino acid-based diets for 5 d supplying either 20 or 10 mg valine.kg body wt-1.d-1, each in combination with 80 or 40 mg leucine.kg-1.d-1. On day 6 subjects were studied with an 8-h continuous intravenous infusion of (1-13C)valine (and (2H3)leucine) to determine valine oxidation in the fasted state (first 3 h) and fed state (last 5 h). Valine oxidation in the fasted state was similar among all diets but was lower (P less than 0.05) in the fed state for the 10 vs 20 mg valine.kg-1.d-1 intake. Leucine intake did not affect valine oxidation. Mean daily valine balance approximated +1.3 mg.kg-1.d-1 for the 20-mg intake and -1.6 mg.kg-1.d-1 for the 10-mg intake. These findings support our previously suggested mean valine requirement estimate of approximately 20 mg.kg-1.d-1.

  2. Exogenous valine reduces conversion of leucine to 3-methyl-1-butanol in Saccharomyces cerevisiae

    SciTech Connect

    Bigelis, R.; Weir, P.D.; Jones, R.R.M.; Umbarger, H.E.

    1983-02-01

    Mutant strains of the yeast Saccharomyces cerevisiae that require branched-chain amino acids must be supplemented with large concentrations (up to 10 mM) of these amino acids to satisfy their nutritional requirements. The utilization of one branched-chain amino acid, leucine, was examined in several leul strains of yeast grown aerobically in a glucose-ammonium salts minimal medium containing a limiting concentration (0.2 mM) of leucine. In this medium, the leucine requirement of the auxotrophic strains could be reduced by valine, another branched-chain amino acid. Increasing the valine concentration increased the cell yields of cultures and also reduced the levels of 3-methyl-1-butanol detected in the medium by gas chromatography. The concentration of 3-methyl-1-butanol was reduced from 122.0 to 48.9 ..mu..M when 5.0 mM valine was supplemented to limiting-leucine cultures. The amino acids isoleucine, threonine, norleucine, norvaline, ..cap alpha..-amino-butyrate, alanine, and glycine also spared the leucine requirement of leucine auxotrophs, most likely because they resemble leucine and competed for its uptake. We propose that leucine analogs restrict the entry and degradation of leucine and thus reduce its conversion to 3-methyl-1-butanol, a major component of fuel oil.

  3. Transport of leucine, isoleucine and valine by luminal membrane vesicles from rabbit proximal tubule.

    PubMed

    Jørgensen, K E; Kragh-Hansen, U; Sheikh, M I

    1990-03-01

    1. Transport of L- and D-isomers of leucine, isoleucine and valine by luminal membrane vesicles prepared from either the convoluted part (pars convoluta) or the straight part (pars recta) of rabbit proximal tubule was studied by a rapid filtration technique and by a spectrophotometric method using a potential-sensitive carbocyanine dye. 2. Both types of renal membrane vesicle take up the amino acids in a Na(+)-dependent, H(+)-independent and electrogenic manner. The L-isomers are transported with higher affinities than their corresponding D-forms, of which only D-leucine is taken up to a significant extent. 3. Membrane vesicles prepared from pars convoluta take up the L-amino acids by a single and common system. Filtration studies showed that the Km values for L-leucine and L-valine transport are, on average, 0.23 and 0.83 mM, respectively. The values of KA (the concentration of amino acid producing a half-maximal optical response) are comparable to those of Km, namely 0.18 mM for L-leucine and 0.60 mM for L-valine. KA for L-isoleucine transport was found to be 0.19 mM. D-Leucine is taken up by the same system but with a much lower affinity (KA = 7.2 mM). 4. Membrane vesicles prepared from pars recta possess two, and probably common, transport systems for the L-isomers of the amino acids. The average Michaelis-Menten constants were as follows: L-leucine, K1m = 0.17 mM, K2m = 6.5 mM; L-valine, K1m = 0.19 mM, K2m = 11.5 mM. The KA values were: L-leucine, K1A = 0.12 mM, K2A = 7.4 mM; L-valine, K1A = 0.18 mM, K2A = 10.0 mM; L-isoleucine, K1A = 0.17 mM, K2A = 9.0 mM. D-Leucine is taken up by a low-affinity system only (KA = 6.5 mM), which seems to be the same as the low-affinity system transporting the L-forms of the amino acids. PMID:2352186

  4. Comparison of deuterated leucine, valine, and lysine in the measurement of human apolipoprotein A-I and B-100 kinetics

    SciTech Connect

    Lichtenstein, A.H.; Cohn, J.S.; Hachey, D.L.; Millar, J.S.; Ordovas, J.M.; Schaefer, E.J. )

    1990-09-01

    The production rates of apolipoprotein (apo)B-100 in very low density lipoprotein and in low density lipoprotein and apolipoprotein A-I in high density lipoprotein were determined using a primed-constant infusion of (5,5,5,-2H3)leucine, (4,4,4,-2H3)valine, and (6,6-2H2,1,2-13C2)lysine. The three stable isotope-labeled amino acids were administered simultaneously to determine whether absolute production rates calculated using a stochastic model were independent of the tracer species utilized. Three normolipidemic adult males were studied in the constantly fed state over a 15-h period. The absolute production rates of very low density lipoprotein apoB-100 were 11.4 +/- 5.8 (leucine), 11.2 +/- 6.8 (valine), and 11.1 +/- 5.4 (lysine) mg per kg per day (mean +/- SDM). The absolute production rates for low density lipoprotein apoB-100 were 8.0 +/- 4.7 (leucine), 7.5 +/- 3.8 (valine), and 7.5 +/- 4.2 (lysine) mg per kg per day. The absolute production rates for high density lipoprotein apoA-I were 9.7 +/- 0.2 (leucine), 9.4 +/- 1.7 (valine), and 9.1 +/- 1.3 (lysine) mg per kg per day. There were no statistically significant differences in absolute synthetic rates of the three apolipoproteins when the plateau isotopic enrichment values of very low density lipoprotein apoB-100 were used to define the isotopic enrichment of the intracellular precursor pool. Our data indicate that deuterated leucine, valine, or lysine provided similar results when used for the determination of apoA-I and apoB-100 absolute production rates within plasma lipoproteins as part of a primed-constant infusion protocol.

  5. Linkage Relationships of Genes Controlling Isoleucine, Valine, and Leucine Biosynthesis in Bacillus subtilis

    PubMed Central

    Barat, M.; Anagnostopoulos, C.; Schneider, A.-M.

    1965-01-01

    Barat, M. (Centre National de la Recherche Scientifique, Gif-sur-Yvette, Seine et Oise, France), C. Anagnostopoulos, and A.-M. Schneider. Linkage relationships of genes controlling isoleucine, valine, and leucine biosynthesis in Bacillus subtilis. J. Bacteriol.90:357–369. 1965.—In Bacillus subtilis, the genetic loci controlling isoleucine and valine biosynthesis are not all clustered. Some of them were located on two distinct transforming deoxyribonucleic acid “molecules.” One of these molecules (the “ileilva2–4-met segment”) carries the threonine deaminase and the dihydroxy acid dehydrase loci linked to methionine markers. The other (the “ilva1–3-leu segment”) bears the reductoisomerase locus and one or more loci involved in leucine synthesis. A phenylalanine marker was also shown to be weakly linked to this latter group. In transduction mediated by phage PBS-1, these groups are transferred jointly with other gene clusters. The phage appears to convey chromosome fragments considerably longer than the transforming “molecules.” The genetic maps of both the above segments were extended by transduction. Some groups previously studied by transformation can be placed in the following linear order: the ile-ilva2–4-met segment, the cluster of loci involved in aromatic amino acid synthesis (try segment), and a lysine locus. An arginine locus is cotransduced with the phe-ilva1–2-leu segment. Recombination frequencies between linked markers are much lower in transduction by this phage than in transformation. PMID:14329448

  6. Providing a diet deficient in valine but with excess leucine results in a rapid decrease in feed intake and modifies the postprandial plasma amino acid and α-keto acid concentrations in pigs.

    PubMed

    Gloaguen, M; Le Floc'h, N; Corrent, E; Primot, Y; van Milgen, J

    2012-09-01

    Indispensable AA are involved in the control of feed intake. When a diet deficient in Val is offered to pigs, feed intake is typically reduced. This effect is aggravated when dietary Leu is supplied in excess of the requirement. If an unbalanced supply of branched-chain AA (BCAA) is harmful, an anorectic response may serve as a mechanism to prevent this situation. We verified this hypothesis by measuring the voluntary feed intake of a balanced diet offered during the 30-min period 1 h after ingestion of a test meal deficient or not in Val (Val- and Val+) with an excess of Leu. Twelve and four 6-wk-old crossbred female pigs were used in Exp. 1 and 2, respectively. Prior ingestion of the Val- test meal resulted in a 14% reduction in feed intake compared with that observed after ingestion of the Val+ test meal (P = 0.06) in Exp. 1, indicating that the signal to reduce feed intake occurred within 1 h. It is possible that the plasma concentration of the limiting AA serves as a signal for the dietary AA deficiency. We therefore determined the postprandial plasma concentrations of BCAA and their α-keto acids after ingestion of Val- and Val+ in 4 pigs in Exp. 2. After ingestion of the Val- diet, plasma concentrations of Val and its keto acid were reduced compared with values observed after ingestion of the Val+ diet. The peak concentration occurred earlier after ingestion of the Val- diet compared with that of the Val+ diet. Although the plasma concentration increased after the meal, it declined rapidly in pigs offered Val-, and the Val concentration 4 h after ingestion of the meal was even less than that observed in the fasted state. In conclusion, it appears that the pig is able to detect a deficient supply of Val within 1 h after ingestion. The plasma concentration of Val or its concentration relative to the other BCAA during the postprandial period may act as a signal indicating the AA deficiency. PMID:22585822

  7. Leucine and alpha-Ketoisocaproic acid, but not norleucine, stimulate skeletal muscle protein synthesis in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The branched-chain amino acid, leucine, acts as a nutrient signal to stimulate protein synthesis in skeletal muscle of young pigs. However, the chemical structure responsible for this effect has not been identified. We have shown that the other branched-chain amino acids, isoleucine and valine, are ...

  8. Examining the critical roles of human CB2 receptor residues Valine 3.32 (113) and Leucine 5.41 (192) in ligand recognition and downstream signaling activities.

    PubMed

    Alqarni, Mohammed; Myint, Kyaw Zeyar; Tong, Qin; Yang, Peng; Bartlow, Patrick; Wang, Lirong; Feng, Rentian; Xie, Xiang-Qun

    2014-09-26

    We performed molecular modeling and docking to predict a putative binding pocket and associated ligand-receptor interactions for human cannabinoid receptor 2 (CB2). Our data showed that two hydrophobic residues came in close contact with three structurally distinct CB2 ligands: CP-55,940, SR144528 and XIE95-26. Site-directed mutagenesis experiments and subsequent functional assays implicated the roles of Valine residue at position 3.32 (V113) and Leucine residue at position 5.41 (L192) in the ligand binding function and downstream signaling activities of the CB2 receptor. Four different point mutations were introduced to the wild type CB2 receptor: V113E, V113L, L192S and L192A. Our results showed that mutation of Val113 with a Glutamic acid and Leu192 with a Serine led to the complete loss of CB2 ligand binding as well as downstream signaling activities. Substitution of these residues with those that have similar hydrophobic side chains such as Leucine (V113L) and Alanine (L192A), however, allowed CB2 to retain both its ligand binding and signaling functions. Our modeling results validated by competition binding and site-directed mutagenesis experiments suggest that residues V113 and L192 play important roles in ligand binding and downstream signaling transduction of the CB2 receptor. PMID:25148941

  9. Evidence for valine intolerance in patients with cirrhosis.

    PubMed

    Schauder, P; Schröder, K; Herbertz, L; Langer, K; Langenbeck, U

    1984-01-01

    Valine (62.5 mg per kg), leucine (70 mg per kg) and equal amounts of the calcium salts of the corresponding keto acids, i.e., alpha-ketoisovaleric acid (KIVA) and alpha-ketoisocaproic acid (KICA) were orally administered to patients with cirrhosis and to control subjects. Valine or leucine ingestion increased serum valine and leucine levels and the corresponding keto acids, KIVA and KICA, in cirrhotics and controls. KIVA or KICA ingestion increased serum KIVA and KICA concentrations within a few minutes associated with a rise in valine and leucine. In cirrhotics, administration of valine or KIVA resulted in significantly higher serum valine or KIVA concentrations than in control subjects. The clearance of valine and KIVA from blood was also delayed in cirrhotic patients. No such differences were observed after leucine or KICA ingestion. It is suggested that cirrhotics have a diminished tolerance for valine. Since the tolerance for KIVA, but not KICA, is also impaired, it appears that cirrhotics have a derangement in one or more metabolic steps distal to the branched-chain keto acid dehydrogenase. PMID:6745855

  10. Influence of the Valine Zipper Region on the Structure and Aggregation of the Basic Leucine Zipper (bZIP) Domain of Activating Transcription Factor 5 (ATF5)

    PubMed Central

    Ciaccio, Natalie A.; Reynolds, T. Steele; Middaugh, C. Russell; Laurence, Jennifer S.

    2012-01-01

    Protein aggregation is a major problem for biopharmaceuticals. While the control of aggregation is critically important for the future of protein pharmaceuticals, mechanisms of aggregate assembly, particularly the role that structure plays, are still poorly understood. Increasing evidence indicates that partially folded intermediates critically influence the aggregation pathway. We have previously reported the use of the basic leucine zipper (bZIP) domain of Activating Transcription Factor 5 (ATF5) as a partially folded model system to investigate protein aggregation. This domain contains three regions with differing structural propensity: a N-terminal polybasic region, a central helical leucine zipper region, and a C-terminal extended valine zipper region. Additionally, a centrally positioned cysteine residue readily forms an intermolecular disulfide bond that reduces aggregation. Computational analysis of ATF5 predicts that the valine zipper region facilitates self-association. Here we test this hypothesis using a truncated mutant lacking the C-terminal valine zipper region. We compare the structure and aggregation of this mutant to the wild-type (WT) form under both reducing and non-reducing conditions. Our data indicate that removal of this region results in a loss of alpha-helical structure in the leucine zipper and a change in the mechanism of self-association. The mutant form displays increased association at low temperature but improved resistance to thermally induced aggregation. PMID:23067245

  11. Conversion of L-leucine to isovaleric acid by Propionibacterium freudenreichii TL 34 and ITGP23.

    PubMed

    Thierry, Anne; Maillard, Marie-Bernadette; Yvon, Mireille

    2002-02-01

    Several branched-chain volatile compounds are involved in the flavor of Swiss cheese. These compounds are probably produced by enzymatic conversion of branched-chain amino acids, but the flora and the pathways involved remain hypothetical. Our aim was to determine the ability of Propionibacterium freudenreichii, which is one of the main components of the secondary flora of Swiss cheese, to produce flavor compounds during leucine catabolism. Cell extracts and resting cells of two strains were incubated in the presence of L-leucine, alpha-ketoglutaric acid, and cofactors, and the metabolites produced were determined by high-performance liquid chromatography and gas chromatography. The first step of leucine catabolism was a transamination that produced alpha-ketoisocaproic acid, which was enzymatically converted to isovaleric acid. Both reactions were faster at pH 8.0 than at acidic pHs. Cell extracts catalyzed only the transamination step under our experimental conditions. Small amounts of 3-methylbutanol were also produced by resting cells, but neither 3-methylbutanal noralpha-hydroxyisocaproic acid was detected. L-Isoleucine and L-valine were also converted to the corresponding acids and alcohols. Isovaleric acid was produced by both strains during growth in a complex medium, even under conditions simulating Swiss cheese conditions (2.1% NaCl, pH 5.4, 24 degrees C). Our results show that P. frendenreichii could play a significant role in the formation of isovaleric acid during ripening. PMID:11823198

  12. Valine entry into rat brain after diet-induced changes in plasma amino acids

    SciTech Connect

    Tews, J.K.; Greenwood, J.; Pratt, O.E.; Harper, A.E.

    1987-01-01

    Passage of amino acids across the blood-brain barrier is assumed to be modified by amino acid composition of the blood. To gain a better understanding of the effects of protein intake on brain amino acid uptake, the authors examined associations among diet, plasma amino acid patterns, and the rate of entry of valine into the brain. Rats were fed diets containing 6, 18, or 50% casein before receiving one meal of a diet containing 0, 6, 18, or 50% casein. After 4-7 h, they were anesthetized and infused intravenously with (/sup 14/C)valine for 5 min before plasma and brain samples were taken for determination of radioactivity and content of individual amino acids. As protein content of the meal was increased from 0 to 50% casein, plasma and brain concentrations of valine and most other large neutral amino acid (LNAA) increased severalfold; also the ratio of (/sup 14/C)valine in brain to that in plasma decreased by >50%, and the rate of valine entry into the brain increased 3.5-fold. The increase in valine flux slowed as plasma levels of LNAA, competitors for valine transport, increased. The results were far more dependent on protein content of the final meal than on that of the adaptation diet; thus changes in protein intake, as reflected in altered plasma amino acid patterns, markedly altered valine entry into the brain.

  13. 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. PMID:24985571

  14. Optimisation of broiler chicken responses from 0 to 7 d of age to dietary leucine, isoleucine and valine using Taguchi and mathematical methods.

    PubMed

    Sedghi, M; Golian, A; Kolahan, F; Afsar, A

    2015-01-01

    Three experiments were conducted to evaluate the applicability of the Taguchi method (TM) and optimisation algorithms to optimise the branch chain amino acids (BCAA) requirements in 0 to 7 d broiler chicks. In the first experiment, the standardised digestible (SID) amino acids and apparent metabolisable energy (AME) values of maize, wheat and soya bean meal were evaluated. In the second experiment, three factors including leucine (Leu), isoleucine (Ile) and valine (Val), each at 4 levels, were selected, and an orthogonal array layout of L16 (4(3)) using TM was performed. After data collection, optimisation of average daily gain (ADG) and feed conversion ratio (FCR) were obtained using TM. The multiobjective genetic algorithm (MOGA) and random search algorithm (RSA) were also applied to predict the optimal combination of BCAA for broiler performance. In the third experiment, a growth study was conducted to evaluate the applicability of obtained optimum BCAA requirements data by TM, MOGA and RSA, and results were compared with those of birds fed with a diet formulated according to Ross 308 recommendations. In the second experiment, the TM resulted in 13.45 g/kg SID Leu, 8.5 g/kg SID Ile and 10.45 g/kg SID Val as optimum level for maximum ADG (21.57 g/bird/d) and minimum FCR (1.11 g feed/g gain) in 0- to 7-d-old broiler chickens. MOGA predicted the following combinations: SID Leu = 14.8, SID Ile = 9.1 and SID Val = 10.3 for maximum ADG (22.05) and minimum FCR (1.11). The optimisation using RSA predicted Leu = 16.0, Ile = 9.5 and Val = 10.2 for maximum ADG (22.67), and Leu = 15.5, Ile = 9.0 and Val = 10.4 to achieve minimum FCR (1.08). The validation experiment confirmed that TM, MOGA and RSA yielded optimum determination of dietary amino acid requirements and improved ADG and FCR as compared to Aviagen recommendations. However, based on the live animal validation trial, MOGA and RSA overpredicted the optimum requirement as compared to TM. In

  15. Specific 13C labeling of leucine, valine and isoleucine methyl groups for unambiguous detection of long-range restraints in protein solid-state NMR studies

    NASA Astrophysics Data System (ADS)

    Fasshuber, Hannes Klaus; Demers, Jean-Philippe; Chevelkov, Veniamin; Giller, Karin; Becker, Stefan; Lange, Adam

    2015-03-01

    Here we present an isotopic labeling strategy to easily obtain unambiguous long-range distance restraints in protein solid-state NMR studies. The method is based on the inclusion of two biosynthetic precursors in the bacterial growth medium, α-ketoisovalerate and α-ketobutyrate, leading to the production of leucine, valine and isoleucine residues that are exclusively 13C labeled on methyl groups. The resulting spectral simplification facilitates the collection of distance restraints, the verification of carbon chemical shift assignments and the measurement of methyl group dynamics. This approach is demonstrated on the type-three secretion system needle of Shigella flexneri, where 49 methyl-methyl and methyl-nitrogen distance restraints including 10 unambiguous long-range distance restraints could be collected. By combining this labeling scheme with ultra-fast MAS and proton detection, the assignment of methyl proton chemical shifts was achieved.

  16. Specific 13C labeling of leucine, valine and isoleucine methyl groups for unambiguous detection of long-range restraints in protein solid-state NMR studies.

    PubMed

    Fasshuber, Hannes Klaus; Demers, Jean-Philippe; Chevelkov, Veniamin; Giller, Karin; Becker, Stefan; Lange, Adam

    2015-03-01

    Here we present an isotopic labeling strategy to easily obtain unambiguous long-range distance restraints in protein solid-state NMR studies. The method is based on the inclusion of two biosynthetic precursors in the bacterial growth medium, α-ketoisovalerate and α-ketobutyrate, leading to the production of leucine, valine and isoleucine residues that are exclusively (13)C labeled on methyl groups. The resulting spectral simplification facilitates the collection of distance restraints, the verification of carbon chemical shift assignments and the measurement of methyl group dynamics. This approach is demonstrated on the type-three secretion system needle of Shigella flexneri, where 49 methyl-methyl and methyl-nitrogen distance restraints including 10 unambiguous long-range distance restraints could be collected. By combining this labeling scheme with ultra-fast MAS and proton detection, the assignment of methyl proton chemical shifts was achieved. PMID:25625825

  17. Leucine acts as a nutrient signal to stimulate protein synthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The postprandial rise in amino acids and insulin independently stimulates protein synthesis in skeletal muscle of piglets. Leucine is an important mediator of the response to amino acids. We have shown that the postprandial rise in leucine, but not isoleucine or valine, acutely stimulates muscle pro...

  18. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine

    NASA Astrophysics Data System (ADS)

    Deborah, M.; Jawahar, A.; Mathavan, T.; Dhas, M. Kumara; Benial, A. Milton Franklin

    2015-03-01

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (0 0 2) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

  19. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine.

    PubMed

    Deborah, M; Jawahar, A; Mathavan, T; Dhas, M Kumara; Benial, A Milton Franklin

    2015-03-15

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery. PMID:25554963

  20. Kinetics of sequential metabolism from D-leucine to L-leucine via alpha-ketoisocaproic acid in rat.

    PubMed

    Hasegawa, Hiroshi; Matsukawa, Takehisa; Shinohara, Yoshihiko; Hashimoto, Takao

    2002-12-01

    D-Leucine is considered to be converted into the L-enantiomer by two steps: oxidative deamination to form alpha-ketoisocaproic acid (KIC) and subsequent stereospecific reamination of KIC. We investigated the pharmacokinetics of leucine enantiomers and KIC in rats to evaluate how deamination of D-leucine, reamination of KIC, and decarboxylation of KIC were affected to the overall extent that converted D-leucine into the L-enantiomer. After intravenous administrations of D-[(2)H(7)]leucine, L-[(2)H(7)]leucine, or [(2)H(7)]KIC, their plasma concentrations together with endogenous L-leucine and KIC were determined by gas chromatography-mass spectrometry. The rapid appearances of [(2)H(7)]KIC and L-[(2)H(7)]leucine were observed after administration of D-[(2)H(7)]leucine, whereas no detectable amount of D-[(2)H(7)]leucine was found after administrations of [(2)H(7)]KIC or L-[(2)H(7)]leucine. The fraction of conversion from D-[(2)H(7)]leucine into [(2)H(7)]KIC (F(D-->KIC)) was estimated by using the area under the curve (AUC) of [(2)H(7)]KIC on the D-[(2)H(7)]leucine administration [AUC(KIC(D))] and that of [(2)H(7)]KIC on the [(2)H(7)]KIC administration (AUC(KIC)) to yield 70.1%. The fraction of conversion from [(2)H(7)]KIC to L-[(2)H(7)]leucine (F(KIC-->L)) was 40.2%. The fraction of conversion from D-leucine to the L-enantiomer (F(D-->L)) was considered to be the product of F(D-->KIC) and F(KIC-->L), indicating that 28.2% of D-[(2)H(7)]leucine was metabolized to L-[(2)H(7)]leucine via [(2)H(7)]KIC. These results suggested that the relatively low conversion of D-leucine into the L-enantiomer might depend on irreversible decarboxylation of KIC. Regardless of [(2)H(7)]KIC, F(D-->L) was also calculated directly using AUC(L(D)) and AUC(L) to yield 27.5%. There were no differences between the two F(D-->L) values, suggesting that almost all of the formation of L-[(2)H(7)]leucine from D-[(2)H(7)]leucine occurred via [(2)H(7)]KIC as an intermediate. PMID:12433816

  1. Clusters of isoleucine, leucine, and valine side chains define cores of stability in high-energy states of globular proteins: Sequence determinants of structure and stability.

    PubMed

    Kathuria, Sagar V; Chan, Yvonne H; Nobrega, R Paul; Özen, Ayşegül; Matthews, C Robert

    2016-03-01

    Measurements of protection against exchange of main chain amide hydrogens (NH) with solvent hydrogens in globular proteins have provided remarkable insights into the structures of rare high-energy states that populate their folding free-energy surfaces. Lacking, however, has been a unifying theory that rationalizes these high-energy states in terms of the structures and sequences of their resident proteins. The Branched Aliphatic Side Chain (BASiC) hypothesis has been developed to explain the observed patterns of protection in a pair of TIM barrel proteins. This hypothesis supposes that the side chains of isoleucine, leucine, and valine (ILV) residues often form large hydrophobic clusters that very effectively impede the penetration of water to their underlying hydrogen bond networks and, thereby, enhance the protection against solvent exchange. The linkage between the secondary and tertiary structures enables these ILV clusters to serve as cores of stability in high-energy partially folded states. Statistically significant correlations between the locations of large ILV clusters in native conformations and strong protection against exchange for a variety of motifs reported in the literature support the generality of the BASiC hypothesis. The results also illustrate the necessity to elaborate this simple hypothesis to account for the roles of adjacent hydrocarbon moieties in defining stability cores of partially folded states along folding reaction coordinates. PMID:26660714

  2. Interactions between Equine Cyclin T1, Tat, and TAR Are Disrupted by a Leucine-to-Valine Substitution Found in Human Cyclin T1

    PubMed Central

    Taube, Ran; Fujinaga, Koh; Irwin, Dan; Wimmer, Jörg; Geyer, Matthias; Peterlin, B. Matija

    2000-01-01

    Transcriptional transactivators (Tat) from human immunodeficiency and equine infectious anemia viruses (HIV and EIAV) interact with their transactivation response elements (TAR) to increase the rates of viral transcription. Whereas the human cyclin T1 is required for the binding of Tat to TAR from HIV, it is unknown how Tat from EIAV interacts with its TAR. Furthermore, Tat from EIAV functions in equine and canine cells but not in human cells. In this study, we present sequences of cyclins T1 from horse and dog and demonstrate that their N-terminal 300 residues rescue the transactivation of Tat from EIAV in human cells. Although human and equine cyclins T1 bind to this Tat, only the equine cyclin T1 supports the binding of Tat to TAR from EIAV. Finally, a reciprocal exchange of the valine for the leucine at position 29 in human and equine cyclins T1, respectively, renders the human cyclin T1 active and the equine cyclin T1 inactive for Tat transactivation from EIAV. Thus, the collaboration between a specific cyclin T1 and Tat for their high-affinity interaction with TAR is a common theme of lentiviral transactivation. PMID:10623752

  3. Metabolism of Valine by the Filamentous Fungus Arthrobotrys conoides1

    PubMed Central

    Gupta, Rishab K.; Pramer, David

    1970-01-01

    Uptake of valine by Arthrobotrys conoides was an active process and was independent of its incorporation into cellular protein. Chemical fractionation of cells supplied with 14C-l-valine for different time intervals revealed that the amino acid initially entered a pool of metabolic intermediates and was extractable with cold trichloroacetic acid. After a 4-min interval, some intracellular valine was incorporated into cell proteins, but most underwent metabolic transformation to a variety of products that included carboxylic acids and other amino acids. Carbon derived from valine was not localized in the lipid or nucleic acid fraction of cells, but some was completely oxidized and recovered as metabolic 14CO2. Autoradiograms of paper and thin-layer chromatograms of acid hydrolysates of cellular protein identified the following amino acids as having originated from valine: glutamate, aspartate, alanine, and leucine. Similar analysis of cold trichloroacetic acid extracts established that 14C supplied as l-valine had been transformed also to α-ketoisovalerate, isobutyrate, propionate, succinate, malate, oxalacetate, pyruvate, and α-ketoglutarate. Pathways for transformation of the carbon skeleton of valine to various metabolic products are proposed. Images PMID:5463679

  4. Role of alanine-valine transaminase in Salmonella typhimurium and analysis of an avtA::Tn5 mutant.

    PubMed Central

    Berg, C M; Whalen, W A; Archambault, L B

    1983-01-01

    In Salmonella typhimurium, as in Escherichia coli, mutations in avtA, the gene encoding the alanine-valine transaminase (transaminase C), are silent unless they are combined with mutations involved in isoleucine-valine biosynthesis. avtA is repressed by leucine or alanine but not by valine. Transaminase C is found at reduced levels upon starvation for any one of several amino acids. We hypothesize that this is due to repression of avtA by the elevated alanine and leucine pools found in amino acid-starved cells. PMID:6309735

  5. Role of alanine-valine transaminase in Salmonella typhimurium and analysis of an avtA::Tn5 mutant.

    PubMed

    Berg, C M; Whalen, W A; Archambault, L B

    1983-09-01

    In Salmonella typhimurium, as in Escherichia coli, mutations in avtA, the gene encoding the alanine-valine transaminase (transaminase C), are silent unless they are combined with mutations involved in isoleucine-valine biosynthesis. avtA is repressed by leucine or alanine but not by valine. Transaminase C is found at reduced levels upon starvation for any one of several amino acids. We hypothesize that this is due to repression of avtA by the elevated alanine and leucine pools found in amino acid-starved cells. PMID:6309735

  6. Enteral leucine and protein synthesis in skeletal and cardiac muscle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are three members of the Branch Chain Amino Acids: leucine, isoleucine, and valine. As essential amino acids, these amino acids have important functions which include a primary role in protein structure and metabolism. It is intriguing that the requirement for BCAA in humans comprise about 40–...

  7. Role of renal D-amino-acid oxidase in pharmacokinetics of D-leucine.

    PubMed

    Hasegawa, Hiroshi; Matsukawa, Takehisa; Shinohara, Yoshihiko; Konno, Ryuichi; Hashimoto, Takao

    2004-07-01

    d-Amino acids are now recognized to be widely present in mammals. Renal d-amino-acid oxidase (DAO) is associated with conversion of d-amino acids to the corresponding alpha-keto acids, but its contribution in vivo is poorly understood because the alpha-keto acids and/or l-amino acids formed are indistinguishable from endogenous compounds. First, we examined whether DAO is indispensable for conversion of d-amino acids to their alpha-keto acids by using the stable isotope tracer technique. After a bolus intravenous administration of d-[(2)H(7)]leucine to mutant mice lacking DAO activity (ddY/DAO(-)) and normal mice (ddY/DAO(+)), elimination of d-[(2)H(7)]leucine and formation of alpha-[(2)H(7)]ketoisocaproic acid ([(2)H(7)]KIC) and l-[(2)H(7)]leucine in plasma were determined. The ddY/DAO(-) mice, in contrast to ddY/DAO(+) mice, failed to convert d-[(2)H(7)]leucine to [(2)H(7)]KIC and l-[(2)H(7)]leucine. This result clearly revealed that DAO was indispensable for the process of chiral inversion of d-leucine. We further investigated the effect of renal mass reduction by partial nephrectomy on elimination of d-[(2)H(7)]leucine and formation of [(2)H(7)]KIC and l-[(2)H(7)]leucine. Renal mass reduction slowed down the elimination of d-[(2)H(7)]leucine. The fraction of conversion of d-[(2)H(7)]leucine to [(2)H(7)]KIC in sham-operated rats was 0.77, whereas that in five-sixths-nephrectomized rats was 0.25. The elimination behavior of d-[(2)H(7)]leucine observed in rats suggested that kidney was the principal organ responsible for converting d-leucine to KIC. PMID:15026304

  8. In vitro transcriptional studies of the bkd operon of Pseudomonas putida: L-branched-chain amino acids and D-leucine are the inducers.

    PubMed

    Madhusudhan, K T; Luo, J; Sokatch, J R

    1999-05-01

    BkdR is the transcriptional activator of the bkd operon, which encodes the four proteins of the branched-chain keto acid dehydrogenase multienzyme complex of Pseudomonas putida. In this study, hydroxyl radical footprinting revealed that BkdR bound to only one face of DNA over the same region identified in DNase I protection assays. Deletions of even a few bases in the 5' region of the BkdR-binding site greatly reduced transcription, confirming that the entire protected region is necessary for transcription. In vitro transcription of the bkd operon was obtained by using a vector containing the bkdR-bkdA1 intergenic region plus the putative rho-independent terminator of the bkd operon. Substrate DNA, BkdR, and any of the L-branched-chain amino acids or D-leucine was required for transcription. Branched-chain keto acids, D-valine, and D-isoleucine did not promote transcription. Therefore, the L-branched-chain amino acids and D-leucine are the inducers of the bkd operon. The concentration of L-valine required for half-maximal transcription was 2.8 mM, which is similar to that needed to cause half-maximal proteolysis due to a conformational change in BkdR. A model for transcriptional activation of the bkd operon by BkdR during enzyme induction which incorporates these results is presented. PMID:10217783

  9. Effect of L-Valine on the growth and characterization of Sodium Acid Phthalate (SAP) single crystals

    NASA Astrophysics Data System (ADS)

    Nirmala, L. Ruby; Prakash, J. Thomas Joseph

    2013-06-01

    Undoped and amino acid doped good quality single crystals of Sodium Acid Phthalate crystals (SAP) were grown by slow evaporation solution growth technique which are semiorganic in nature. The effect of amino acid (L-Valine) dopant on the growth and the properties of SAP single crystal was investigated. The single crystal X-ray diffraction studies and FT-IR studies were carried out to identify the crystal structure and the presence of functional groups in undoped and L-Valine doped SAP crystals. The transparent nature of the grown crystal was observed using UV-Visible spectrum. The thermal decomposition of the doped SAP crystals was investigated by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). The enhancement in the NLO property of the undoped and L-Valine doped SAP crystals using KDP crystal as a reference was studied using SHG measurements. Vickers micro hardness measurements are used for the study of mechanical strength of the grown crystals.

  10. Continuous recovery of valine in a model mixture of amino acids and salt from Corynebacterium bacteria fermentation using a simulated moving bed chromatography.

    PubMed

    Park, Chanhun; Nam, Hee-Geun; Jo, Se-Hee; Wang, Nien-Hwa Linda; Mun, Sungyong

    2016-02-26

    The economical efficiency of valine production in related industries is largely affected by the performance of a valine separation process, in which valine is to be separated from leucine, alanine, and ammonium sulfate. Such separation is currently handled by a batch-mode hybrid process based on ion-exchange and crystallization schemes. To make a substantial improvement in the economical efficiency of an industrial valine production, such a batch-mode process based on two different separation schemes needs to be converted into a continuous-mode separation process based on a single separation scheme. To address this issue, a simulated moving bed (SMB) technology was applied in this study to the development of a continuous-mode valine-separation chromatographic process with uniformity in adsorbent and liquid phases. It was first found that a Chromalite-PCG600C resin could be eligible for the adsorbent of such process, particularly in an industrial scale. The intrinsic parameters of each component on the Chromalite-PCG600C adsorbent were determined and then utilized in selecting a proper set of configurations for SMB units, columns, and ports, under which the SMB operating parameters were optimized with a genetic algorithm. Finally, the optimized SMB based on the selected configurations was tested experimentally, which confirmed its effectiveness in continuous separation of valine from leucine, alanine, ammonium sulfate with high purity, high yield, high throughput, and high valine product concentration. It is thus expected that the developed SMB process in this study will be able to serve as one of the trustworthy ways of improving the economical efficiency of an industrial valine production process. PMID:26830632

  11. Stimulation of muscle protein synthesis by leucine is dependent on plasma amino acid availability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have reported that a physiological increase in plasma leucine increased translation initiation factor activity during 60- and 120-min leucine infusion. Muscle protein synthesis was stimulated at 60 min but not at 120 min, perhaps due to the decrease (-50%) in plasma essential amino acids (AA). ...

  12. Long-term leucine induced stimulation of muscle protein synthesis is amino acid dependent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infusing leucine for 1 h increases skeletal muscle protein synthesis in the neonate, but this is not sustained for 2 h unless the corresponding fall in amino acids is prevented. This study aimed to determine whether a continuous leucine infusion can stimulate protein synthesis for a prolonged period...

  13. Regulation of transaminase C synthesis in Escherichia coli: conditional leucine auxotrophy.

    PubMed

    McGilvray, D; Umbarger, H E

    1974-11-01

    The regulation of synthesis of the valine-alanine-alpha-aminobutyrate transaminase (transaminase C) was studied in Escherichia coli mutants lacking the branched-chain amino acid transaminase (transaminase B). An investigation was made of two strains, CU2 and CU2002, each carrying the same transaminase B lesion but exhibiting different growth responses on a medium supplemented with branched-chain amino acids. Both had the absolute isoleucine requirement characteristic of ilvE auxotrophs, but growth of strain CU2 was stimulated by valine, whereas that of strain CU2002 was markedly inhibited by valine. Strain CU2002 behaved like a conditional leucine auxotroph in that the inhibition by valine was reversed by leucine. Results of enzymatic studies showed that synthesis of transaminase C was repressed by valine in strain CU2002 but not in strain CU2. Inhibition by valine in strain CU2002 appears to be the combined effect of repression on transaminase C synthesis and valine-dependent feedback inhibition of alpha-acetohydroxy acid synthase activity, causing alpha-ketoisovalerate (and hence leucine) limitation. The ilvE markers of strains CU2 and CU2002 were each transferred by transduction to a wild-type genetical background. All ilvE recombinants from both crosses resembled strain CU2002 and were inhibited by valine in the presence of isoleucine. Thus, strain CU2 carries an additional lesion that allows it to grow on a medium containing isoleucine plus valine. It is concluded that conditional leucine auxotrophy is characteristic of mutants carrying an ilvE lesion alone. PMID:4616947

  14. Amino acid transport across the tonoplast of vacuoles isolated from barley mesophyll protoplasts: Uptake of alanine, leucine, and glutamine. [Hordeum vulgare L

    SciTech Connect

    Dietz, K.J.; Jaeger, R.; Kaiser, G.; Martinoia, E. )

    1990-01-01

    Mesophyll protoplasts from leaves of well-fertilized barley (Hordeum vulgare L.) plants contained amino acids at concentrations as high as 120 millimoles per liter. With the exception of glutamic acid, which is predominantly localized in the cytoplasm, a major part of all other amino acids was contained inside the large central vacuole. Alanine, leucine, and glutamine are the dominant vacuolar amino acids in barley. Their transport into isolated vacuoles was studied using {sup 14}C-labeled amino acids. Uptake was slow in the absence of ATP. A three- to sixfold stimulation of uptake was observed after addition of ATP or adenylyl imidodiphosphate an ATP analogue not being hydrolyzed by ATPases. Other nucleotides were ineffective in increasing the rate of uptake. ATP-Stimulated amino acid transport was not dependent on the transtonoplast pH or membrane potential. p-Chloromercuriphenylsulfonic acid and n-ethyl maleimide increased transport independently of ATP. Neutral amino acids such as valine or leucine effectively decreased the rate of alanine transport. Glutamine and glycine were less effective or not effective as competitive inhibitors of alanine transport. The results indicate the existence of a uniport translocator specific for neutral or basic amino acids that is under control of metabolic effectors.

  15. Stimulation of muscle protein synthesis by prolonged parenteral infusion of leucine is dependent on amino acid availability in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The postprandial rise in amino acids, particularly leucine, stimulates muscle protein synthesis in neonates. Previously, we showed that a 1-h infusion of leucine increased protein synthesis, but this response was not sustained for 2 h unless the leucine-induced decrease in amino acids was prevented....

  16. Stimulation of skeletal muscle protein synthesis in neonatal pigs by long-term infusion of leucine is amino acid dependent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infusing leucine for 1 hr increases skeletal muscle protein synthesis in neonatal pigs, but this is not sustained for 2 h unless the leucine-induced fall in amino acids is prevented. We aimed to determine whether continuous leucine infusion can stimulate protein synthesis for a prolonged period whe...

  17. LEUCINE STIMULATION OF SKELETAL MUSCLE PROTEIN SYNTHESIS DURING PROLONGED LEUCINE INFUSION IS DEPENDENT ON AMINO ACID AVAILABILITY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leucine stimulates protein synthesis in cultured cells, mature rats and neonatal pigs. We have reported that leucine infusion increases protein synthesis in skeletal muscle of neonatal pigs during a 60-min infusion. When leucine infusion was prolonged for 120 min, however, protein synthesis was no...

  18. Predicting Three-Dimensional Conformations of Peptides Constructed of Only Glycine, Alanine, Aspartic Acid, and Valine

    NASA Astrophysics Data System (ADS)

    Oda, Akifumi; Fukuyoshi, Shuichi

    2015-06-01

    The GADV hypothesis is a form of the protein world hypothesis, which suggests that life originated from proteins (Lacey et al. 1999; Ikehara 2002; Andras 2006). In the GADV hypothesis, life is thought to have originated from primitive proteins constructed of only glycine, alanine, aspartic acid, and valine ([GADV]-proteins). In this study, the three-dimensional (3D) conformations of randomly generated short [GADV]-peptides were computationally investigated using replica-exchange molecular dynamics (REMD) simulations (Sugita and Okamoto 1999). Because the peptides used in this study consisted of only 20 residues each, they could not form certain 3D structures. However, the conformational tendencies of the peptides were elucidated by analyzing the conformational ensembles generated by REMD simulations. The results indicate that secondary structures can be formed in several randomly generated [GADV]-peptides. A long helical structure was found in one of the hydrophobic peptides, supporting the conjecture of the GADV hypothesis that many peptides aggregated to form peptide multimers with enzymatic activity in the primordial soup. In addition, these results indicate that REMD simulations can be used for the structural investigation of short peptides.

  19. Prolonged stimulation of muscle protein synthesis by leucine in neonates is dependent on amino acid availability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rise in amino acids and insulin after a meal independently stimulate protein synthesis in skeletal muscle of neonates by activating the intracellular signalling pathways that regulate mRNA translation. Leucine, in particular, is important in mediating the response to amino acids. Previously, w...

  20. Partial derepression of the isoleucine-valine enzymes during methionine starvation is Salmonella typhimurium.

    PubMed

    Rizzino, A; Mastanduno, M; Freundlich, M

    1977-03-18

    Methionine starvation of methionine auxotrophs in the presence of excess branched-chain amino acids results in a partial derepression of the isoleucine and valine enzymes. Reversed-phase chromatography indicated that isoleucine, valine and leucine tRNA were altered during methionine starvation. In addition, the total tRNA isolated from cells under these conditions were undermethylated. The observed derepression may be caused by the inability of methyl-deficient tRNA's to participate adequately in normal regulatory functions. PMID:321028

  1. Effects of leucine supplementation and serum withdrawal on branched-chain amino acid pathway gene and protein expression in mouse adipocytes.

    PubMed

    Kitsy, Abderrazak; Carney, Skyla; Vivar, Juan C; Knight, Megan S; Pointer, Mildred A; Gwathmey, Judith K; Ghosh, Sujoy

    2014-01-01

    The essential branched-chain amino acids (BCAA), leucine, valine and isoleucine, are traditionally associated with skeletal muscle growth and maintenance, energy production, and generation of neurotransmitter and gluconeogenic precursors. Recent evidence from human and animal model studies has established an additional link between BCAA levels and obesity. However, details of the mechanism of regulation of BCAA metabolism during adipogenesis are largely unknown. We interrogated whether the expression of genes and proteins involved in BCAA metabolism are sensitive to the adipocyte differentiation process, and responsive to nutrient stress from starvation or BCAA excess. Murine 3T3-L1 preadipocytes were differentiated to adipocytes under control conditions and under conditions of L-leucine supplementation or serum withdrawal. RNA and proteins were isolated at days 0, 4 and 10 of differentiation to represent pre-differentiation, early differentiation and late differentiation stages. Expression of 16 BCAA metabolism genes was quantified by quantitative real-time PCR. Expression of the protein levels of branched-chain amino acid transaminase 2 (Bcat2) and branched-chain alpha keto acid dehydrogenase (Bckdha) was quantified by immunoblotting. Under control conditions, all genes displayed induction of gene expression during early adipogenesis (Day 4) compared to Day 0. Leucine supplementation resulted in an induction of Bcat2 and Bckdha genes during early and late differentiation. Western blot analysis demonstrated condition-specific concordance between gene and protein expression. Serum withdrawal resulted in undetectable Bcat2 and Bckdha protein levels at all timepoints. These results demonstrate that the expression of genes related to BCAA metabolism are regulated during adipocyte differentiation and influenced by nutrient levels. These results provide additional insights on how BCAA metabolism is associated with adipose tissue function and extends our understanding of

  2. EFFECT OF THE LEUCINE ANALOGS, ALPHA-KETOISOCAPROIC ACID (KIC) AND NORLEUCINE, ON MUSCLE PROTEIN SYNTHESIS AND TRANSLATION INITIATION FACTOR ACTIVATION IN NEONATAL PIGS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leucine acts as a nutrient signal to stimulate protein synthesis in skeletal muscle of neonatal pigs; however, the chemical structure responsible for this effect has not been identified. We have shown that isoleucine and valine are not able to stimulate protein synthesis when raised in plasma withi...

  3. Mechanism of specific influence of L-Glutamic acid on the shape of L-Valine crystals

    NASA Astrophysics Data System (ADS)

    Yoshiura, Hiromu; Nagano, Hiroshi; Hirasawa, Izumi

    2013-01-01

    The specific interaction between L-valine (L-Val) and L-glutamic acid (L-Glu) in the process of evaporative crystallization from an aqueous solution has been investigated. It was found that only 2.0% (wt/wt) of L-Glu against the total amount of L-Val was required to induce significant agglomeration of L-Val. Interestingly, the agglomeration was only induced under acidic conditions, suggesting that the electrostatic interaction was an effective factor for the agglomeration process. As well as the electrostatic interaction, the length of the amino acid side chain was identified as another important factor. In addition, we confirmed that the incorporation rate of L-Glu into L-Val crystals was different during the nucleation and crystal growth stages. Based on these results, a mechanism has been proposed for the interaction of L-Glu and L-Val during the agglomeration process.

  4. Acetohydroxy acid synthase I, a required enzyme for isoleucine and valine biosynthesis in Escherichia coli K-12 during growth on acetate as the sole carbon source.

    PubMed Central

    Dailey, F E; Cronan, J E

    1986-01-01

    Escherichia coli K-12 has two acetohydroxy acid synthase (AHAS) isozymes (AHAS I and AHAS III). Both of these isozymes catalyze the synthesis of alpha-aceto-alpha-hydroxybutyrate and alpha-acetolactate, which are key intermediates of the isoleucine-valine biosynthetic pathway. Strains lacking either isozyme but not both activities have been previously shown to grow well in minimal media in the absence of isoleucine and valine on any of several commonly used carbon sources (e.g., glucose or succinate). We report the characterization of mutants that were unable to grow on either acetate or oleate as a sole carbon source due to a defect in isoleucine-valine biosynthesis. The defect in isoleucine-valine biosynthesis was expressed only on these carbon sources and was due to the loss of AHAS I activity, resulting from lesions in the ilvBN operon. Previously identified ilvBN mutant strains also failed to grow on acetate or oleate minimal media. Our results indicated that AHAS I is an essential enzyme for isoleucine and valine biosynthesis when E. coli K-12 is grown on acetate or oleate as the sole carbon source. AHAS III was expressed during growth on acetate or oleate but was somehow unable to produce sufficient amounts of alpha-aceto-alpha-hydroxybutyrate and alpha-acetolactate to allow growth. PMID:3511034

  5. Effect of strength training session on plasma amino acid concentration following oral ingestion of leucine, BCAAs or glutamine in men.

    PubMed

    Mero, Antti; Leikas, Anne; Knuutinen, Juha; Hulmi, Juha J; Kovanen, Vuokko

    2009-01-01

    We examined the acute effects of a 1-h strength training session (STS) on plasma amino acid concentration following orally ingestion of leucine, branched-chain amino acids (BCAAs) or glutamine in nine physically active men who participated in double-blinded and randomised experiments. The subjects took placebo, leucine, BCAAs, or glutamine capsules (50 mg/kg) in either rest (REST) or STS condition. Blood samples were taken before and at 30, 60, 90, and 120 min after the beginning of the treatment and they were assayed for plasma amino acids with HPLC. Following both leucine and BCAA ingestion the peak concentration of leucine was similar at rest (524 +/- 46 and 530 +/- 29 nmol/ml, respectively) and similar after STS (398 +/- 43 and 387 +/- 46 nmol/ml, respectively) but the rest and STS concentrations differed from each other (P < 0.01-0.001). The modelled polynomial data for the leucine treatment showed that the peak concentration of leucine occurred at 67 min at rest and at 90 min in STS (difference between REST and STS: P = 0.012). For the BCAA treatment the polynomial data showed that the peak concentration of leucine occurred at 72 min at rest and at 78 min in STS (P = 0.067). The peak concentration of glutamine was similar in both rest and STS condition and occurred at 60 min at rest and at 57 min in STS. In conclusion, 1-h of STS slows the increase in the peak concentration of plasma leucine similarly after oral ingestion of leucine or BCAAs but after oral ingestion of glutamine it has no slowing effect on glutamine concentration. PMID:19015870

  6. Suppression of Endogenous Glucose Production by Isoleucine and Valine and Impact of Diet Composition.

    PubMed

    Arrieta-Cruz, Isabel; Su, Ya; Gutiérrez-Juárez, Roger

    2016-02-01

    Leucine has been shown to acutely inhibit hepatic glucose production in rodents by a mechanism requiring its metabolism to acetyl-CoA in the mediobasal hypothalamus (MBH). In the early stages, all branched-chain amino acids (BCAA) are metabolized by a shared set of enzymes to produce a ketoacid, which is later metabolized to acetyl-CoA. Consequently, isoleucine and valine may also modulate glucose metabolism. To examine this possibility we performed intrahypothalamic infusions of isoleucine or valine in rats and assessed whole body glucose kinetics under basal conditions and during euglycemic pancreatic clamps. Furthermore, because high fat diet (HFD) consumption is known to interfere with central glucoregulation, we also asked whether the action of BCAAs was affected by HFD. We fed rats a lard-rich diet for a short interval and examined their response to central leucine. The results showed that both isoleucine and valine individually lowered blood glucose by decreasing liver glucose production. Furthermore, the action of the BCAA leucine was markedly attenuated by HFD feeding. We conclude that all three BCAAs centrally modulate glucose metabolism in the liver and that their action is disrupted by HFD-induced insulin resistance. PMID:26891318

  7. Suppression of Endogenous Glucose Production by Isoleucine and Valine and Impact of Diet Composition

    PubMed Central

    Arrieta-Cruz, Isabel; Su, Ya; Gutiérrez-Juárez, Roger

    2016-01-01

    Leucine has been shown to acutely inhibit hepatic glucose production in rodents by a mechanism requiring its metabolism to acetyl-CoA in the mediobasal hypothalamus (MBH). In the early stages, all branched-chain amino acids (BCAA) are metabolized by a shared set of enzymes to produce a ketoacid, which is later metabolized to acetyl-CoA. Consequently, isoleucine and valine may also modulate glucose metabolism. To examine this possibility we performed intrahypothalamic infusions of isoleucine or valine in rats and assessed whole body glucose kinetics under basal conditions and during euglycemic pancreatic clamps. Furthermore, because high fat diet (HFD) consumption is known to interfere with central glucoregulation, we also asked whether the action of BCAAs was affected by HFD. We fed rats a lard-rich diet for a short interval and examined their response to central leucine. The results showed that both isoleucine and valine individually lowered blood glucose by decreasing liver glucose production. Furthermore, the action of the BCAA leucine was markedly attenuated by HFD feeding. We conclude that all three BCAAs centrally modulate glucose metabolism in the liver and that their action is disrupted by HFD-induced insulin resistance. PMID:26891318

  8. Acetohydroxy acid synthase I is required for isoleucine and valine biosynthesis by Salmonella typhimurium LT2 during growth on acetate or long-chain fatty acids.

    PubMed

    Dailey, F E; Cronan, J E; Maloy, S R

    1987-02-01

    Salmonella typhimurium LT2 normally expresses two acetohydroxy acid synthases (AHAS I and AHAS II). The function of AHAS I in this organism was unclear, since AHAS I-deficient (ilvBN) mutants of LT2 grew well on glucose or succinate minimal media, whereas AHAS II-deficient (ilvGM) mutants requried isoleucine for normal growth on glucose minimal media. We report that AHAS I-deficient mutants of S. typhimurium required isoleucine and valine for growth on acetate or oleate minimal media, whereas AHAS II-deficient mutants were able to grow on these media without isoleucine supplementation. PMID:3542980

  9. Supplemental leucine and isoleucine affect expression of cationic amino acid transporters and myosin, serum concentration of amino acids, and growth performance of pigs.

    PubMed

    Cervantes-Ramírez, M; Mendez-Trujillo, V; Araiza-Piña, B A; Barrera-Silva, M A; González-Mendoza, D; Morales-Trejo, A

    2013-01-01

    Leucine (Leu) participates in the activity of cationic amino acid (aa) transporters. Also, branched-chain aa [Leu, isoleucine (Ile), and valine (Val)] share intestinal transporters for absorption. We conducted an experiment with 16 young pigs (body weight of about 16 kg) to determine whether Leu and Ile affect expression of aa transporters b(0,+) and CAT-1 in the jejunum and expression of myosin in muscle, as well as serum concentration of essential aa, and growth performance in pigs. Dietary treatments were: wheat-based diets fortified with Lys, Thr, and Met; basal diet plus 0.50% Leu; basal diet plus 0.50% Ile, and basal diet plus 0.50% Leu and 0.50% Ile. After 28 days, the pigs were sacrificed to collect blood, jejunum, and semitendinosus and longissimus muscle samples. The effects of single and combined addition of Leu and Ile were analyzed. Leu alone or combined with Ile significantly decreased daily weight gain and reduced feed conversion. Leu and Ile, alone or in combination, significantly decreased expression of b(0,+) and significantly increased CAT-1. Ile alone or combined with Leu significantly decreased myosin expression in semitendinosus and significantly decreased it in longissimus muscle. Leu alone significantly decreased Lys, Ile and Thr serum concentrations; Ile significantly decreased Thr serum concentration; combined Leu and Ile significantly decreased Thr and significantly increased Val serum concentration. We conclude that dietary levels of Leu and Ile affect growth performance, expression of aa transporters and myosin, and aa serum concentrations in pigs. PMID:23408397

  10. Leucine disposal rate for assessment of amino acid metabolism in maintenance hemodialysis patients

    PubMed Central

    Denny, Gerald B.; Deger, Serpil M.; Chen, Guanhua; Bian, Aihua; Sha, Feng; Booker, Cindy; Kesler, Jaclyn T.; David, Sthuthi; Ellis, Charles D.; Ikizler, T. Alp

    2016-01-01

    Background Protein energy wasting (PEW) is common in patients undergoing maintenance hemodialysis (MHD) and closely associated with poor outcomes. Insulin resistance and associated alterations in amino acid metabolism are potential pathways leading to PEW. We hypothesized that the measurement of leucine disposal during a hyperinsulinemic- euglycemic-euaminoacidemic clamp (HEAC) procedure would accurately measure the sensitivity to insulin for its actions on concomitant carbohydrate and protein metabolism in MHD patients. Methods We examined 35 MHD patients and 17 control subjects with normal kidney function by hyperinsulinemic-euglycemic clamp (HEGC) followed by HEAC clamp procedure to obtain leucine disposal rate (LDR) along with isotope tracer methodology to assess whole body protein turnover. Results The glucose disposal rate (GDR) by HEGC was 5.1 ± 2.1 mg/kg/min for the MHD patients compared to 6.3 ± 3.9 mg/kg/min for the controls (p = 0.38). The LDR during HEAC was 0.09 ± 0.03 mg/kg/min for the MHD patients compared to 0.11 ± 0.05 mg/kg/min for the controls (p = 0.009). The LDR level was correlated with whole body protein synthesis (r = 0.25; p = 0.08), with whole body protein breakdown (r = −0.38 p = 0.01) and net protein balance (r = 0.85; p < 0.001) in the overall study population. Correlations remained significant in subgroup analysis. The GDR derived by HEGC and LDR correlated well in the controls (r = 0.79, p < 0.001), but less so in the MHD patients (r = 0.58, p < 0.001). Conclusions Leucine disposal rate reliably measures amino acid utilization in MHD patients and controls in response to high dose insulin. PMID:27413537

  11. Biosynthesis of 4-methyleneglutamic acid by peanut seedlings: Evidence for the involvement of a distinct source of leucine

    SciTech Connect

    Winter, H.C.; Dekker, E.E. )

    1989-04-01

    Germinating peanut seeds accumulate 4-methyleneglutamic acid its {gamma}-amide(MeGlx), as well as 4-methylglutamic acid(MGlu) for which leucine has been implicated as a precursor. When we incubated detached peanut cotyledons with {sup 14}C-leucine for 24-96 hr, most of the label was found in non-extractable components, while small but significant amounts were present in MeGlx, MGlu, and free leucine. The level of leucine in storage protein of ungerminated seeds is similar to the maximum level of MeGlx found in germinated seeds; further correlations were observed in various peanut tissues between rapid accumulation of MeGlx and the presence of high levels of glyoxysomal enzymes (catalase and isocitrate lyase). These results suggest that during germination, most of the leucine in the seed storage protein is converted to MeGlx, possibly by a glyoxysomal oxidase system in cotyledons, whereas most of the free leucine for protein synthesis is formed de novo.

  12. D-valine as an indicator for metabolic changes in L-valine

    SciTech Connect

    Faulhaber, P.; Bartlett, R.; Lathrop, K.A.; Harper, P.V.

    1985-05-01

    Racemic C-11-carboxyl labeled amino acids are easily prepared and have been proven useful as pancreatic imaging agents in humans. The authors are continuing an investigation of the biokinetics and metabolism of one of these, C-11 labeled valine using the D-enantiomer to measure tissue distribution of ''unchanged'' valine and comparing it to L-valine. Mice were injected IV with D-, L-, or D,L-valine, and data collected for various tissues, exhaled CO/sub 2/ and urine at intervals between 1 and 150 min. The % injected activity (IA) per organ for D-valine was multiplied by the ratio of the % retained activity (RA) for L-valine to % RA for D-valine. This value is assumed to represent ''unchanged'' L-valine; it was subtracted from the measured % IA for L-valine to give metabolized C-11. Greatest differences are an increasing excess of --15% for small intestine (SI) and an increasing deficit of --15% for muscle at 120 min. Muscle is apparently an active site for incorporation of C-11 from L-valine into other molecules which are then concentrated in the SI. Some tissues were homogenized in chloroform-methanol (2:1), mixed with a small amount of water, centrifuged, and the 3 resulting layers assayed for C-11. In the liver, for example, at 15 and 45 min there was no activity in the chloroform layer for D-, or L-valine. The aqueous layer contained 18% sample activity (SA) at 15 min and 10% SA at 45 min for L-valine, and --78% SA at both times for D-valine; the tissue layer contained 82% SA and 91% SA, for L-valine, and --22% SA for D-valine at both times. Use of enantiomers in this way gives the possibility of quantitating isolated metabolic processes.

  13. A Single Acyl-CoA Dehydrogenase Is Required For Catabolism Of Isoleucine, Valine And Short-Chain Fatty Acids In Aspergillus nidulans

    PubMed Central

    Maggio-Hall, Lori A.; Lyne, Paul; Wolff, Jon A.; Keller, Nancy P.

    2010-01-01

    An acyl-CoA dehydrogenase has been identified as part of the mitochondrial β-oxidation pathway in the ascomycete fungus Aspergillus nidulans. Disruption of the scdA gene prevented use of butyric acid (C4) and hexanoic acid (C6) as carbon sources and reduced cellular butyryl-CoA dehydrogenase activity by 7.5-fold. While the mutant strain exhibited wild-type levels of growth on erucic acid (C22:1) and oleic acid (C18:1), some reduction in growth was observed with myristic acid (C14). The ΔscdA mutation was found to be epistatic to a mutation downstream in the β-oxidation pathway (disruption of enoyl-CoA hydratase). The ΔscdA mutant was also unable to use isoleucine or valine as a carbon source. Transcription of scdA was observed in the presence of either fatty acids or amino acids. When the mutant was grown in medium containing either isoleucine or valine, organic acid analysis of culture supernatants showed accumulation of 2-oxo acid intermediates of branched chain amino acid catabolism, suggesting feedback inhibition of the upstream branched-chain α-keto acid dehydrogenase. PMID:17656140

  14. Evidence that the branched-chain amino acid L-valine prevents exercise-induced release of 5-HT in rat hippocampus.

    PubMed

    Gomez-Merino, D; Béquet, F; Berthelot, M; Riverain, S; Chennaoui, M; Guezennec, C Y

    2001-07-01

    The branched-chain amino acid L-valine competes with tryptophan for transport into the brain and has previously been shown to decrease brain 5-HT synthesis. The purpose of this study was to assess, using a combined venous catheterization and in vivo microdialysis method, the effect of pre-exercise L-valine administration on 5-hydroxytryptamine (5-HT) metabolism in the ventral hippocampus of rats submitted to an acute intensive treadmill running (120 min at 25 m x min(-1) followed by 150 min of recovery). The presented results include measurement of extracellular tryptophan (TRP), the 5-HT precursor, and extracellular 5-hydroxyindoleacetic acid (5-HIAA), the 5-HT metabolite. The data clearly demonstrate that exercise induces 5-HT release in the rat hippocampus: in control group, hippocampal 5-HT levels increase from 123.7 +/- 6.4% at the end of exercise to 133.9 +/- 6.4% after 60 min of recovery. Moreover, two hours of intensive running induced significant increases both in extracellular TRP levels (from 120 min of exercise to 30 min of recovery) and 5-HIAA levels (from 90 min of exercise to 90 min of recovery). Pre-exercise administration of L-valine prevents significantly the exercise-induced 5-HT release: 5-HT levels are maintained to baseline during exercise and recovery. With regard to the competitive effect of L-valine with TRP, we could observe a treatment-induced decrease in brain TRP levels (from 120 min of exercise to the end of recovery). Besides, L-valine does not prevent exercise-induced increase in 5-HIAA levels. The present study evidences that an acute intensive exercise stimulates 5-HT metabolism in the rat hippocampus, and that a pre-exercise administration of L-valine prevents, via a limiting effect on 5-HT synthesis, exercise-induced 5-HT release. This study provides some anwers to previous human and animal investigations, showing physiological and psychological benefits of branched-chain amino acids supplementation on performance. PMID:11510866

  15. Reaction of dehydropyrrolizidine alkaloids with valine and hemoglobin.

    PubMed

    Zhao, Yuewei; Wang, Shuguang; Xia, Qingsu; Gamboa da Costa, Gonçalo; Doerge, Daniel R; Cai, Lining; Fu, Peter P

    2014-10-20

    Pyrrolizidine alkaloid-containing plants are probably the most common poisonous plants affecting livestock, wildlife, and humans. Pyrrolizidine alkaloids exert toxicity through metabolism to dehydropyrrolizidine alkaloids that bind to cellular protein and DNA, leading to hepatotoxicity, genotoxicity, and tumorigenicity. To date, it is not clear how dehydropyrrolizidine alkaloids bind to cellular constituents, including amino acids and proteins, resulting in toxicity. Metabolism of carcinogenic monocrotaline, riddelliine, and heliotrine produces dehydromonocrotaline, dehyroriddelliine, and dehydroheliotrine, respectively, as primary reactive metabolites. In this study, we report that reaction of dehydromonocrotaline with valine generated four highly unstable 6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP)-derived valine (DHP-valine) adducts. For structural elucidation, DHP-valine adducts were derivatized with phenyl isothiocyanate (PITC) to DHP-valine-PITC products. After HPLC separation, their structures were characterized by mass spectrometry, UV-visible spectrophotometry, (1)H NMR, and (1)H-(1)H COSY NMR spectral analysis. Two DHP-valine-PITC adducts, designated as DHP-valine-PITC-1 and DHP-valine-PITC-3, had the amino group of valine linked to the C7 position of the necine base, and the other two DHP-valine-PITC products, DHP-valine-PITC-2 and DHP-valine-PITC-4, linked to the C9 position of the necine base. DHP-valine-PITC-1 was interconvertible with DHP-valine-PITC-3, and DHP-valine-PITC-2 was interconvertible with DHP-valine-PITC-4. Reaction of dehydroriddelliine and dehydroheliotrine with valine provided similar results. However, reaction of valine and dehydroretronecine (DHR) under similar experimental conditions did not produce DHP-valine adducts. Reaction of dehydromonocrotaline with rat hemoglobin followed by derivatization with PITC also generated the same four DHP-valine-PITC adducts. This represents the first full structural elucidation of

  16. Metabolism of orally administered branched-chain alpha-keto acids.

    PubMed

    Dalton, R N; Chantler, C

    1983-11-01

    The changes in serum branched-chain alpha-keto acid (BCKA) and plasma amino acid concentrations, in response to a therapeutic oral dose of an essential amino acid/keto acid mixture, were studied in fasting healthy adults. Of the branched-chain amino acids (BCAA), only the plasma leucine concentration rose significantly despite increases in al three serum BCKA concentrations. The plasma valine concentration tended to rise, but plasma isoleucine concentrations fell. When KMVA (keto-isoleucine) alone was given, there followed an increase in plasma isoleucine concentration and a fall in valine and leucine. Similarly, when KIVA (keto-valine) was given, plasma valine rose and leucine and isoleucine fell. These results suggest some transamination of the keto acid with amino groups of the other BCAA. KICA (keto-leucine), however, produced larger falls in plasma valine and isoleucine than was expected from the rise in leucine. In addition, KICA caused significant, insulin-independent reductions in plasma threonine, serine, cystine, methionine, tyrosine, phenylalanine, and alanine. We conclude that although orally administered BCKA's will increase the BCAA supply, their value may not simply relate to the supply of essential amino acids for protein synthesis but to a direct effect of KICA on protein metabolism. PMID:6368946

  17. High Leucine Diets Stimulate Cerebral Branched-Chain Amino Acid Degradation and Modify Serotonin and Ketone Body Concentrations in a Pig Model.

    PubMed

    Wessels, Anna G; Kluge, Holger; Hirche, Frank; Kiowski, Andreas; Schutkowski, Alexandra; Corrent, Etienne; Bartelt, Jörg; König, Bettina; Stangl, Gabriele I

    2016-01-01

    In addition to its role as an essential protein component, leucine (Leu) displays several other metabolic functions such as activation of protein synthesis. This property makes it an interesting amino acid for the therapy of human muscle atrophy and for livestock production. However, Leu can stimulate its own degradation via the branched-chain keto acid dehydrogenase complex (BCKDH). To examine the response of several tissues to excessive Leu, pigs were fed diets containing two- (L2) and four-fold (L4) higher Leu contents than the recommended amount (control). We found that the L4 diet led to a pronounced increase in BCKDH activity in the brain (2.5-fold, P < 0.05), liver (1.8-fold, P < 0.05) and cardiac muscle (1.7-fold, P < 0.05), whereas we found no changes in enzyme activity in the pancreas, skeletal muscle, adipose tissue and intestinal mucosa. The L2 diet had only weak effects on BCKDH activity. Both high Leu diets reduced the concentrations of free valine and isoleucine in nearly all tissues. In the brain, high Leu diets modified the amount of tryptophan available: for serotonin synthesis. Compared to the controls, pigs treated with the high Leu diets consumed less food, showed increased plasma concentrations of 3-hydroxybutyrate and reduced levels of circulating serotonin. In conclusion, excessive Leu can stimulate BCKDH activity in several tissues, including the brain. Changes in cerebral tryptophan, along with the changes in amino acid-derived metabolites in the plasma may limit the use of high Leu diets to treat muscle atrophy or to increase muscle growth. PMID:26930301

  18. 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

  19. Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BACKGROUND: The effects of essential amino acid (EAA) supplementation during moderate steady state (ie, endurance) exercise on postexercise skeletal muscle metabolism are not well described, and the potential role of supplemental leucine on muscle protein synthesis (MPS) and associated molecular re...

  20. Distinct Plasma Profile of Polar Neutral Amino Acids, Leucine, and Glutamate in Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Tirouvanziam, Rabindra; Obukhanych, Tetyana V.; Laval, Julie; Aronov, Pavel A.; Libove, Robin; Banerjee, Arpita Goswami; Parker, Karen J.; O'Hara, Ruth; Herzenberg, Leonard A.; Herzenberg, Leonore A.; Hardan, Antonio Y.

    2012-01-01

    The goal of this investigation was to examine plasma amino acid (AA) levels in children with Autism Spectrum Disorders (ASD, N = 27) and neuro-typically developing controls (N = 20). We observed reduced plasma levels of most polar neutral AA and leucine in children with ASD. This AA profile conferred significant post hoc power for discriminating…

  1. A chiral ligand exchange CE essay with zinc(II)-L-valine complex for determining enzyme kinetic constant of L-amino acid oxidase.

    PubMed

    Qi, Li; Yang, Gengliang; Zhang, Haizhi; Qiao, Juan

    2010-06-15

    A new strategy for the enantioseparation of D,L-amino acids employing the principle of ligand exchange capillary electrophoresis with Zn(II)-L-valine complex as a chiral selecting system in the presence of beta-cyclodextrin has been designed. Successful enantioseparation of label free and labeled amino acids have been achieved with a buffer of 100.0mM boric acid, 5.0mM ammonium acetate, 4.0mM beta-cyclodextrin, 4.0mM ZnSO(4) and 8.0mM L-valine at pH 8.1. This new method was shown to be applicable to the quantitative analysis of label free D- and L-aromatic amino acids. Furthermore, the expanding enzymatic use of L-amino acid oxidase to incubate with different L-amino acids has allowed understanding of the substrate's specificity. An on-column incubation assay has been developed to study the L-amino acid oxidase's catalytic efficiency. It was demonstrated that the enzyme kinetic constant could be determined by using this new method. PMID:20441938

  2. Heat-initiated prebiotic formation of peptides from glycine/aspartic acid and glycine/valine in aqueous environment and clay suspension

    NASA Astrophysics Data System (ADS)

    Pant, Chandra Kala; Lata, Hem; Pathak, Hari Datt; Mehata, Mohan Singh

    2009-04-01

    The effect of heat on the reaction system of glycine/aspartic acid and glycine/valine in the aqueous environment as well as in montmorillonite clay suspension with or without divalent cations (Ca2+, Mg2+ and Ni2+) has been investigated at 85°C±5°C for varying periods under prebiotic drying and wetting conditions. The resulting products were analysed and characterized by chromatographic and spectroscopic methods. Peptide formation appears to depend on the duration of heat effect, nature of reactant amino acids and, to some extent, on montmorillonite clay incorporated with divalent cations. In the glycine/aspartic acid system, oligomerization of glycine was limited up to trimer level (Gly)3 along with the formation of glycyl-aspartic acid, while linear and cyclic peptides of aspartic acid were not formed, whereas the glycine/valine system preferentially elongated homo-oligopeptide of glycine up to pentamer level (Gly)5 along with formation of hetero-peptides (Gly-Val and Val-Gly). These studies are relevant in the context of the prebiotic origin of proteins and the role of clay and metal ions in condensation and oligomerization of amino acids. The length of the bio-oligomer chain depends upon the reaction conditions. However, condensation into even a small length seems significant, as the same process would have taken millions of years in the primitive era of the Earth, leading to the first proteins.

  3. D-Amino acids influence ultrasonic calling in mice pups: effects of D-phenylalanine and D-leucine.

    PubMed

    Albonetti, M E; D'Udine, B; Oliverio, A

    1985-06-24

    6-day-old mice pups were injected with D-amino acids (D-phenyl-alanine + D-leucine), and their ultrasonic distress vocalizations were measured. D-Amino acids, which exert opioid-like effects, reduce the number of ultrasonic calls without affecting the activity of the pups. This effect is reversed by naloxone, an opioid antagonist. The role of endogenous opioids in modulating early attachment is discussed. PMID:4041020

  4. Leucine-enriched essential amino acids attenuate inflammation in rat muscle and enhance muscle repair after eccentric contraction.

    PubMed

    Kato, Hiroyuki; Miura, Kyoko; Nakano, Sayako; Suzuki, Katsuya; Bannai, Makoto; Inoue, Yoshiko

    2016-09-01

    Eccentric exercise results in prolonged muscle damage that may lead to muscle dysfunction. Although inflammation is essential to recover from muscle damage, excessive inflammation may also induce secondary damage, and should thus be suppressed. In this study, we investigated the effect of leucine-enriched essential amino acids on muscle inflammation and recovery after eccentric contraction. These amino acids are known to stimulate muscle protein synthesis via mammalian target of rapamycin (mTOR), which, is also considered to alleviate inflammation. Five sets of 10 eccentric contractions were induced by electrical stimulation in the tibialis anterior muscle of male SpragueDawley rats (8-9 weeks old) under anesthesia. Animals received a 1 g/kg dose of a mixture containing 40 % leucine and 60 % other essential amino acids or distilled water once a day throughout the experiment. Muscle dysfunction was assessed based on isometric dorsiflexion torque, while inflammation was evaluated by histochemistry. Gene expression of inflammatory cytokines and myogenic regulatory factors was also measured. We found that leucine-enriched essential amino acids restored full muscle function within 14 days, at which point rats treated with distilled water had not fully recovered. Indeed, muscle function was stronger 3 days after eccentric contraction in rats treated with amino acids than in those treated with distilled water. The amino acid mix also alleviated expression of interleukin-6 and impeded infiltration of inflammatory cells into muscle, but did not suppress expression of myogenic regulatory factors. These results suggest that leucine-enriched amino acids accelerate recovery from muscle damage by preventing excessive inflammation. PMID:27168073

  5. Effects of running the Bostom Marathon on plasma concentrations of large neutral amino acids

    NASA Technical Reports Server (NTRS)

    Conlay, L. A.; Wurtman, R. J.; Lopez G-Coviella, I.; Blusztajn, J. K.; Vacanti, C. A.; Logue, M.; During, M.; Caballero, B.; Maher, T. J.; Evoniuk, G.

    1989-01-01

    Plasma large neutral amino acid concentrations were measured in thirty-seven subjects before and after completing the Boston Marathon. Concentrations of tyrosine, phenylalanine, and methionine increased, as did their 'plasma ratios' (i.e., the ratio of each amino acid's concentration to the summed plasma concentrations of the other large neutral amino acids which compete with it for brain uptake). No changes were noted in the plasma concentrations of tryptophan, leucine, isoleucine, nor valine; however, the 'plasma ratios' of valine, leucine, and isoleucine all decreased. These changes in plasma amino acid patterns may influence neurotransmitter synthesis.

  6. Blood-brain barrier permeability to leucine-enkephalin, D-alanine2-D-leucine5-enkephalin and their N-terminal amino acid (tyrosine).

    PubMed

    Zlokovic, B V; Begley, D J; Chain-Eliash, D G

    1985-06-10

    The permeability of the blood-brain barrier to [tyrosyl-3,5-3H]enkephalin-(5-L-leucine) (abbreviated to Leu-Enk) and of its synthetic analogue D-alanine2-[tyrosyl-3,5-3H]enkephalin-(5-D-leucine) (abbreviated to D-Ala2-D-Leu5-Enk) was studied, in the adult rat, by means of Oldendorf's27 intracarotid injection technique. The brain uptake index (BUI) corrected for residual vascular radioactivity was about the same for both peptides, indicating a low extraction from the blood during a 5- or 15-s period of exposure to the peptides. Transport of Leu-Enk was not saturated by unlabelled Enk at a concentration as high as 5 mM but was completely abolished by 5mM tyrosine and by the inhibitor of aminopeptidase activity, bacitracin (2 mM). Also the typical L-transport system substrate, 2-aminobicyclo(2,2,1)heptane-2 carboxylic acid (BCH)9 at 10 mM concentration markedly reduced (by 80%) Leu-Enk uptake by the brain. In contrast, brain uptake of D-Ala2-D-Leu5-Enk was reduced only to about one-half of its control value by bacitracin or by 25% by BCH. Brain uptake for L-tyrosine was typically large and markedly inhibited by BCH but not inhibited by 5 mM unlabelled Leu-Enk. These results show that the measurable but low first-pass extractions for enkephalins are not representative of the uptake of these peptides into the brain, but rather reflect their extreme sensitivity to enzymatic degradation with a release of the N-terminal tyrosine residue. The results also suggest that small amounts of D-Ala2-D-Leu5-Enk might cross the blood-brain barrier in an intact form.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3891014

  7. Asymmetrical transfer of alpha-aminoisobutyric acid (AIB), leucine and lysine across the in vitro perfused human placenta.

    PubMed

    Schneider, H; Proegler, M; Sodha, R; Dancis, J

    1987-01-01

    The mechanism for establishing transplacental gradients for leucine, lysine and alpha-aminoisobutyric acid (AIB) has been investigated in the perfused human placenta. Experiments were done with either the maternal or the fetal circulation closed and the donor circulation open. Transfer of the amino acids towards the fetal side was more rapid than it was in the reverse direction. When the maternal perfusate was recirculated, the amino acid concentrations were maintained at a considerably lower level in the maternal circulation than in the open fetal circuit. When the fetal circuit was closed, the concentrations approached or slightly exceeded those in the maternal perfusate over a period of three hours. Within the placenta, higher concentrations were established during the experiments with transfer towards the fetal side than in the reverse direction. Of the three amino acids, leucine was transferred most rapidly across the placenta while AIB reached the highest concentrations in the placental tissue. The asymmetry of the transplacental amino acid flux is favoured by rapid uptake from the maternal circulation and transfer towards the fetus. Both rates exceed those observed in the reverse direction. The transfer rate of D-leucine was 1.7 times that of L-glucose. For in vitro studies of the transfer rate of physiological compounds a correction for diffusion is required. The results may differ considerably depending on which marker is used as the basis. PMID:3112761

  8. Involvement of the Neutral Amino Acid Transporter SLC6A15 and Leucine in Obesity-Related Phenotypes

    PubMed Central

    Drgonova, Jana; Jacobsson, Josefin A.; Han, Joan C.; Yanovski, Jack A.; Fredriksson, Robert; Marcus, Claude; Schiöth, Helgi B.; Uhl, George R.

    2013-01-01

    Brain pathways, including those in hypothalamus and nucleus of the solitary tract, influence food intake, nutrient preferences, metabolism and development of obesity in ways that often differ between males and females. Branched chain amino acids, including leucine, can suppress food intake, alter metabolism and change vulnerability to obesity. The SLC6A15 (v7-3) gene encodes a sodium-dependent transporter of leucine and other branched chain amino acids that is expressed by neurons in hypothalamus and nucleus of the solitary tract. We now report that SLC6A15 knockout attenuates leucine's abilities to reduce both: a) intake of normal chow and b) weight gain produced by access to a high fat diet in gender-selective fashions. We identify SNPs in the human SLC6A15 that are associated with body mass index and insulin resistance in males. These observations in mice and humans support a novel, gender-selective role for brain amino acid compartmentalization mediated by SLC6A15 in diet and obesity-associated phenotypes. PMID:24023709

  9. 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<Leucineleucine (40%, P < 0.05) and placebo (100%, P < 0.05). In summary, EAA ingestion appears to stimulate translation initiation more effectively than the other supplements, although the results also suggest that this effect is primarily attributable to the BCAA. PMID:27053525

  10. Failure of dietary leucine to influence the tryptophan-niacin pathway in the chicken.

    PubMed

    Penz, A M; Clifford, A J; Rogers, Q R; Kratzer, F H

    1984-01-01

    Three experiments were conducted with young chicks to determine whether dietary leucine affects the conversion of tryptophan to niacin. Either tryptophan or niacin improved growth and reduced perosis when chicks were fed a purified diet marginal in tryptophan and deficient in niacin. Addition of 4.8% L-leucine to the diet did not alter the growth and perosis prevention response obtained with tryptophan. Liver weight was slightly increased by the addition of 5.4% L-leucine to the diet. Plasma insulin was slightly reduced by leucine and by isoleucine and valine. Picolinic carboxylase in the kidney was reduced in chicks fed 0.2% tryptophan with no niacin and was also reduced when isoleucine and valine were added to the diets. Liver picolinic carboxylase activity was not influenced by diet. Plasma isoleucine and valine were reduced by the addition of leucine to the diet and were increased again when isoleucine and valine were added to the diet. Plasma leucine was increased by the addition of leucine but was not altered by valine and isoleucine. Plasma tryptophan was not influenced by dietary supplements of leucine or isoleucine and valine. The results show that in the chick there is no evidence for an effect of leucine on the tryptophan to niacin pathway. PMID:6693983

  11. Leucine metabolism in rat liver after a bolus injection of endotoxin.

    PubMed

    Holecek, M; Sprongl, L; Tichý, M; Pecka, M

    1998-06-01

    To evaluate the contribution of hepatic tissue to alterations in the metabolism of proteins and the branched-chain amino acids (BCAA) leucine, isoleucine, and valine in systemic inflammatory response syndrome, we studied the changes of leucine metabolism in isolated perfused liver (IPL) of endotoxin-treated rats. Male albino rats were injected with the endotoxin of Salmonella enteritidis (5 mg x kg(-1)) or saline (control). Four hours later, leucine and ketoisocaproate (KIC) oxidation and incorporation into liver proteins were determined in IPL using the single-pass liver perfusion technique. L-[1-(14)C]leucine and alpha-keto[1-(14)C]isocaproic acid were used as a tracer in two separate experiments. Endotoxin treatment resulted in a decrease of plasma BCAA levels, an increase of leucine oxidation, and a decrease of KIC oxidation by IPL. Leucine incorporation into liver proteins was lower in endotoxin-treated rats, and we did not find measurable incorporation of the labeled carbon of KIC in liver proteins in either group of animals. The sum of individual amino acid concentrations in the effluent perfusate was higher in endotoxin-treated animals, although only leucine and phenylalanine increased significantly. The decrease in KIC oxidation indicates a decreased capacity of hepatic tissue to oxidize branched-chain ketoacids (BCKA). The increase in leucine oxidation by IPL of endotoxin-treated rats indicates an increase in BCAA aminotransferase activity. These changes demonstrate an important response of the body that enables the resynthesis of essential BCAA from their ketoanalogs delivered to the liver from peripheral tissues, particularly muscle. PMID:9627366

  12. 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.

  13. Regulation of branched-chain amino acid transport in Escherichia coli.

    PubMed Central

    Quay, S C; Oxender, D L

    1976-01-01

    The repression and derepression of leucine, isoleucine, and valine transport in Escherichia coli K-12 was examined by using strains auxotrophic for leucine, isoleucine, valine, and methionine. In experiments designed to limit each of these amino acids separately, we demonstrate that leucine limitation alone derepressed the leucine-binding protein, the high-affinity branched-chain amino acid transport system (LIV-I), and the membrane-bound, low-affinity system (LIV-II). This regulation did not seem to involve inactivation of transport components, but represented an increase in the differential rate of synthesis of transport components relative to total cellular proteins. The apparent regulation of transport by isoleucine, valine, and methionine reported elsewhere was shown to require an intact leucine, biosynthetic operon and to result from changes in the level of leucine biosynthetic enzymes. A functional leucyl-transfer ribonucleic acid synthetase was also required for repression of transport. Transport regulation was shown to be essentially independent of ilvA or its gene product, threonine deaminase. The central role of leucine or its derivatives in cellular metabolism in general is discussed. PMID:783137

  14. L-leucine, L-methionine, and L-phenylalanine share a Na(+)/K (+)-dependent amino acid transporter in shrimp hepatopancreas.

    PubMed

    Duka, Ada; Ahearn, Gregory A

    2013-08-01

    Hepatopancreatic brush border membrane vesicles (BBMV), made from Atlantic White shrimp (Litopenaeus setiferus), were used to characterize the transport properties of (3)H-L-leucine influx by these membrane systems and how other essential amino acids and the cations, sodium and potassium, interact with this transport system. (3)H-L-leucine uptake by BBMV was pH-sensitive and occurred against transient transmembrane concentration gradients in both Na(+)- and K(+)-containing incubation media, suggesting that either cation was capable of providing a driving force for amino acid accumulation. (3)H-L-leucine uptake in NaCl or KCl media were each three times greater in acidic pH (pH 5.5) than in alkaline pH (pH 8.5). The essential amino acid, L-methionine, at 20 mM significantly (p < 0.0001) inhibited the 2-min uptakes of 1 mM (3)H-L-leucine in both Na(+)- and K(+)-containing incubation media. The residual (3)H-L-leucine uptake in the two media were significantly greater than zero (p < 0.001), but not significantly different from each other (p > 0.05) and may represent an L-methionine- and cation-independent transport system. (3)H-L-leucine influxes in both NaCl and KCl incubation media were hyperbolic functions of [L-leucine], following the carrier-mediated Michaelis-Menten equation. In NaCl, (3)H-L-leucine influx displayed a low apparent K M (high affinity) and low apparent J max, while in KCl the transport exhibited a high apparent K M (low affinity) and high apparent J max. L-methionine or L-phenylalanine (7 and 20 mM) were competitive inhibitors of (3)H-L-leucine influxes in both NaCl and KCl media, producing a significant (p < 0.01) increase in (3)H-L-leucine influx K M, but no significant response in (3)H-L-leucine influx J max. Potassium was a competitive inhibitor of sodium co-transport with (3)H-L-leucine, significantly (p < 0.01) increasing (3)H-L-leucine influx K M in the presence of sodium, but having negligible effect on (3)H-L-leucine influx J

  15. Valine adsorption and electrooxidation at carbon materials

    SciTech Connect

    Aleksandrova, L.R.; Andreev, V.N.; Bogdanovskaya, V.A.; Safronov, A.Yu.

    1987-08-01

    The authors study the electrochemical behavior of valine (which is contained on most proteins) at electrodes made of carbon materials. The electrochemical behavior of valine at carbon materials was studied potentiodynamically. Adsorption measurements involving radiotracers were performed. The valine with C/sub 1//sup 14/ label was 1% of the total amino acid concentration. Potentiodynamic curves measured at an electrode of BM-4 carbon in base electrolyte solution are presented. The results of measurements made in solutions of different pH and at different electrode materials are given. It is found that the mesoporous BM-4 carbon has the highest adsorption capacity for amino acid, while electrooxidation only occurs in neutral solutions, but at all types of carbon materials.

  16. Possible involvement of phospholipase C and protein kinase C in stimulatory actions of L-leucine and its keto acid, alpha-ketoisocaproic acid, on protein synthesis in RLC-16 hepatocytes.

    PubMed

    Yagasaki, Kazumi; Morisaki-Tsuji, Naoko; Miura, Atsuhito; Funabiki, Ryuhei

    2002-11-01

    Effects of leucine and related compounds on protein synthesis were studied in RLC-16 hepatocytes. The incorporation of [(3)H] tyrosine into cellular protein was measured as an indexof protein synthesis. In leucine-depleted RLC-16 cells, L-leucineand its keto acid, alpha-ketoisocaproic acid (KIC), stimulated protein synthesis, while D-leucine did not. Mepacrine, an inhibitor of both phospholipase A(2) and C canceled stimulatory actions of L-leucine and KIC on protein synthesis, suggesting a possible involvement of either arachidonic acid metabolism by phospholipase A(2), cyclooxygenase or lipoxygenase, or phosphatidylinositol degradation by phospholipase C in the stimulatory actions of L-leucine and KIC.Neither indomethacin, an inhibitor of cyclooxygenase, nor caffeic acid, an inhibitor of lipoxygenase, diminished their stimulatory actions, suggesting no involvement of arachidonic acid metabolism. Conversely, 1-O-hexadecyl-2-O-methylglycerol, an inhibitor of protein kinase C, significantly canceled the stimulatory actions of L-leucine and KIC on protein synthesis, suggesting an involvement of phosphatidylinositol degradation and activation of protein kinase C. These results strongly suggest that both L-leucine and KIC stimulate protein synthesis in RLC-16 cells via activation of phospholipase C and production of diacylglycerol and inositol triphosphate from phosphatidylinositol, which in turn activate protein kinase C. PMID:19003115

  17. Some non-anomerically C-C-linked carbohydrate amino acids related to leucine-synthesis and structure determination.

    PubMed

    Steiner, Bohumil; Micová, Júlia; Koós, Miroslav; Langer, Vratislav; Gyepesová, Dalma

    2003-06-23

    (5'R)-5'-Isobutyl-5'-[methyl (4R)-2,3-O-isopropylidene-beta-L-erythrofuranosid-4-C-yl]-imidazolidin-2',4'-dione was synthesised starting from methyl 2,3-O-isopropylidene-alpha-D-lyxo-pentodialdo-1,4-furanoside via methyl 6-deoxy-6-isopropyl-2,3-O-isopropylidene-alpha-D-lyxo-hexofuranosid-5-ulose applying the Bucherer-Bergs reaction. Its 5'-R configuration was confirmed by X-ray crystallography. Corresponding alpha-amino acid-methyl (5R)-5-amino-5-C-carboxy-5,6-dideoxy-6-isopropyl-alpha-D-lyxo-hexofuranoside (alternative name: 2-[methyl (4R)-beta-L-erythrofuranosid-4-C-yl]-D-leucine) was obtained from the above hydantoin by acid hydrolysis of the isopropylidene group followed by basic hydrolysis of the hydantoin ring. Analogous derivatives with 5S configuration, formed in a minority, were also isolated and characterised. PMID:12801708

  18. Regulation of amino acid transport in Escherichia coli by transcription termination factor rho.

    PubMed Central

    Quay, S C; Oxender, D L

    1977-01-01

    Amino acid transport rates and amino acid binding proteins were examined in a strain containing the rho-120 mutation (formerly SuA), which has been shown to lower the rho-dependent, ribonucleic acid-activated adenosine triphosphatase activity to 9% of the rho activity in the isogenic wild-type strain. Tryptophan and proline transport, which occur by membrane-bound systems, were not altered. On the other hand, arginine, histidine, leucine, isoleucine, and valine transport were variably increased by a factor of 1.4 to 5.0. Kinetics of leucine transport showed that the LIV (leucine, isoleucine, and valine)-I (binding protein-associated) transport system is increased 8.5-fold, whereas the LIV-II (membrane-bound) system is increased 1.5-fold in the rho mutant under leucine-limited growth conditions. The leucine binding protein is increased fourfold under the same growth conditions. The difference in leucine transport in these strains was greatest during leucine-limited growth; growth on complex media repressed both strains to the same transport activity. We propose that rho-dependent transcriptional termination is important for leucine-specific repression of branched-chain amino acid transport, although rho-independent regulation, presumably by a corepressor-aporepressor-type mechanism, must also occur. PMID:324970

  19. Activation of the mTOR pathway by the amino acid (L)-leucine in the 5q- syndrome and other ribosomopathies.

    PubMed

    Boultwood, Jacqueline; Yip, Bon Ham; Vuppusetty, Chaitanya; Pellagatti, Andrea; Wainscoat, James S

    2013-01-01

    Patients with the 5q- syndrome and Diamond-Blackfan anemia (DBA) suffer from a severe macrocytic anemia. The 5q- syndrome and DBA are disorders of aberrant ribosome biogenesis (ribosomopathies) and haploinsufficiency of the ribosomal protein genes RPS14 and RPS19, respectively, underlies the anemia found in these disorders. Erythroblasts obtained from patients with the 5q- syndrome and DBA show impaired mRNA translation and this defect in translation may represent a potential therapeutic target in these ribosomopathies. There are some indications that the amino acid l-leucine, a translation enhancer, may have some efficacy in this group of disorders. Recent studies have shown that l-leucine treatment of zebrafish and murine models of the 5q- syndrome and DBA results in a marked improvement in the anemia. l-leucine treatment of RPS14-deficient and RPS19-deficient erythroblasts and erythroblasts from patients with the 5q- syndrome has been shown to result in an increase in cell proliferation, erythroid differentiation and mRNA translation in culture. l-leucine has been shown to improve hemoglobin levels and transfusion independence in a patient with DBA. l-leucine activates the mTOR (mammalian target of rapamycin) signaling pathway that controls cell growth and mRNA translation. There is evidence to suggest that the promotion of translation via the mTOR pathway by l-leucine is the mechanism that underlies the enhanced erythroid progenitor cell growth and differentiation observed in animal and cellular models of the 5q- syndrome and DBA treated with this amino acid. These data support the rationale for clinical trials of l-leucine as a therapeutic agent for the 5q- syndrome and DBA. PMID:23031788

  20. Association of Valine and Leucine at HLA–DRB1 Position 11 With Radiographic Progression in Rheumatoid Arthritis, Independent of the Shared Epitope Alleles but Not Independent of Anti–Citrullinated Protein Antibodies

    PubMed Central

    van Steenbergen, H. W.; Raychaudhuri, S.; Rodríguez-Rodríguez, L.; Rantapää-Dahlqvist, S.; Berglin, E.; Toes, R. E. M.; Huizinga, T. W. J.; Fernández-Gutiérrez, B.; Gregersen, P. K.; van der Helm-van Mil, A. H. M.

    2015-01-01

    Objective For decades it has been known that the HLA–DRB1 shared epitope (SE) alleles are associated with an increased risk of development and progression of rheumatoid arthritis (RA). Recently, the following variations in the peptide-binding grooves of HLA molecules that predispose to RA development have been identified: Val and Leu at HLA–DRB1 position 11, Asp at HLA–B position 9, and Phe at HLA–DPB1 position 9. This study was undertaken to investigate whether these variants are also associated with radiographic progression in RA, independent of SE and anti–citrullinated protein antibody (ACPA) status. Methods A total of 4,911 radiograph sets from 1,878 RA patients included in the Leiden Early Arthritis Clinic (The Netherlands), Umeå (Sweden), Hospital Clinico San Carlos–Rheumatoid Arthritis (Spain), and National Data Bank for Rheumatic Diseases (US) cohorts were studied. HLA was imputed using single-nucleotide polymorphism data from an Immunochip, and the amino acids listed above were tested in relation to radiographic progression per cohort using an additive model. Results from the 4 cohorts were combined in inverse-variance weighted meta-analyses using a fixed-effects model. Analyses were conditioned on SE and ACPA status. Results Val and Leu at HLA–DRB1 position 11 were associated with more radiographic progression (meta-analysis P = 5.11 × 10−7); this effect was independent of SE status (meta-analysis P = 0.022) but not independent of ACPA status. Phe at HLA–DPB1 position 9 was associated with more severe radiographic progression (meta-analysis P = 0.024), though not independent of SE status. Asp at HLA–B position 9 was not associated with radiographic progression. Conclusion Val and Leu at HLA–DRB1 position 11 conferred a risk of a higher rate of radiographic progression independent of SE status but not independent of ACPA status. These findings support the relevance of these amino acids at position 11. PMID:25580908

  1. Organic Reference Materials for Hydrogen, Carbon, and Nitrogen Stable Isotope-Ratio Measurements: Caffeines, n-Alkanes, Fatty Acid Methyl Esters, Glycines, L-Valines, Polyethylenes, and Oils.

    PubMed

    Schimmelmann, Arndt; Qi, Haiping; Coplen, Tyler B; Brand, Willi A; Fong, Jon; Meier-Augenstein, Wolfram; Kemp, Helen F; Toman, Blaza; Ackermann, Annika; Assonov, Sergey; Aerts-Bijma, Anita T; Brejcha, Ramona; Chikaraishi, Yoshito; Darwish, Tamim; Elsner, Martin; Gehre, Matthias; Geilmann, Heike; Gröning, Manfred; Hélie, Jean-François; Herrero-Martín, Sara; Meijer, Harro A J; Sauer, Peter E; Sessions, Alex L; Werner, Roland A

    2016-04-19

    An international project developed, quality-tested, and determined isotope-δ values of 19 new organic reference materials (RMs) for hydrogen, carbon, and nitrogen stable isotope-ratio measurements, in addition to analyzing pre-existing RMs NBS 22 (oil), IAEA-CH-7 (polyethylene foil), and IAEA-600 (caffeine). These new RMs enable users to normalize measurements of samples to isotope-δ scales. The RMs span a range of δ(2)H(VSMOW-SLAP) values from -210.8 to +397.0 mUr or ‰, for δ(13)C(VPDB-LSVEC) from -40.81 to +0.49 mUr and for δ(15)N(Air) from -5.21 to +61.53 mUr. Many of the new RMs are amenable to gas and liquid chromatography. The RMs include triads of isotopically contrasting caffeines, C16 n-alkanes, n-C20-fatty acid methyl esters (FAMEs), glycines, and l-valines, together with polyethylene powder and string, one n-C17-FAME, a vacuum oil (NBS 22a) to replace NBS 22 oil, and a (2)H-enriched vacuum oil. A total of 11 laboratories from 7 countries used multiple analytical approaches and instrumentation for 2-point isotopic normalization against international primary measurement standards. The use of reference waters in silver tubes allowed direct normalization of δ(2)H values of organic materials against isotopic reference waters following the principle of identical treatment. Bayesian statistical analysis yielded the mean values reported here. New RMs are numbered from USGS61 through USGS78, in addition to NBS 22a. Because of exchangeable hydrogen, amino acid RMs currently are recommended only for carbon- and nitrogen-isotope measurements. Some amino acids contain (13)C and carbon-bound organic (2)H-enrichments at different molecular sites to provide RMs for potential site-specific isotopic analysis in future studies. PMID:26974360

  2. A fifth member of the tomato 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase gene family harbours a leucine zipper and is anaerobically induced.

    PubMed

    Sell, Simone; Hehl, Reinhard

    2005-02-01

    Using the leucine zipper domain of a small anaerobically induced bZIP transcription factor in a yeast two hybrid screen, anaerobically induced genes were identified. One peptide corresponds to an anaerobically induced IDS4-like protein that maybe involved in G-protein signaling. Surprisingly, another interacting peptide corresponds to a novel anaerobically induced 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase, designated ACO5. ACO5 harbours a leucine zipper and transcription is mainly induced in fruits and to a lesser extend in leaves. The role of ACO5 in the low oxygen response of tomato is discussed. PMID:16040352

  3. Leucine metabolism in TNF-alpha- and endotoxin-treated rats: contribution of hepatic tissue.

    PubMed

    Holecek, M; Sprongl, L; Skopec, F; Andrýs, C; Pecka, M

    1997-12-01

    The effects of tumor necrosis factor-alpha (TNF-alpha; cachectin) and lipopolysaccharide of Salmonella enteritidis (LPS; endotoxin) on leucine metabolism in rats were evaluated in the whole body using intravenous infusion of L-[1-14C]leucine and in isolated perfused liver (IPL) using the single-pass perfusion technique with alpha-keto[1-14C]isocaproate as a tracer for measurement of ketoisocaproic acid (KIC) oxidation, and the recirculation technique for measurement of hepatic amino acid exchanges. The data obtained in TNF-alpha and LPS groups were compared with those obtained in controls. Both TNF-alpha and LPS treatment induced an increase of whole body leucine turnover, oxidation, and clearance. As the result of a higher increase of leucine oxidation than of incorporation into the pool of body proteins, the fractional oxidation of leucine was increased. The fractional rate of protein synthesis increased significantly in the spleen (both in TNF-alpha and LPS rats), in blood plasma, liver, colon, kidneys, gastrocnemius muscle (in LPS rats), and in lungs (TNF-alpha-treated rats), whereas it decreased in the jejunum (LPS rats). In IPL of TNF-alpha- and LPS-treated rats a decrease of KIC oxidation and higher uptake of branched-chain amino acids (BCAA; valine, leucine, and isoleucine) were observed when compared with control animals. We hypothesize that the negative consequences of increased whole body proteolysis and of increased oxidation of BCAA induced by TNF-alpha and/or LPS are reduced by decreased activity of hepatic branched-chain ketoacid dehydrogenase that can help resupply BCAA to the body. PMID:9435518

  4. Decarboxylation of [1-(13)C]leucine by hydroxyl radicals.

    PubMed

    Guitton, J; Tinardon, F; Lamrini, R; Lacan, P; Desage, M; Francina, A

    1998-08-01

    The decarboxylation of [1-13C]leucine by hydroxyl radicals was studied by using gas chromatography-isotope ratio mass spectrometry (GC-IRMS) to follow the production of 13CO2. A Fenton reaction between a (Fe2+)-porphyrin and hydrogen peroxide under aerobic conditions yielded hydroxyl radicals. The decarboxylation rates (VLeu) measured by GC-IRMS were dependent on [1-13C]leucine, porphyrin and hydrogen peroxide concentrations. The 13CO2 production was also dependent on bicarbonate or carbon dioxide added in the reaction medium. Bicarbonate facilitated 13CO2 production, whereas carbon dioxide decreased 13CO2 production. Proton effects on some decarboxylation intermediates could explain bicarbonate or carbon dioxide effects. No effect on the decarboxylation rates was observed in the presence of the classical hydroxyl radicals scavengers dimethyl sulfoxide, mannitol, and uric acid. By contrast, a competitive effect with a strong decrease of the decarboxylation rates was observed in the presence of various amino acids: unlabeled leucine, valine, phenylalanine, cysteine, lysine, and histidine. Two reaction products, methyl-4 oxo-2 pentanoate and methyl-3 butanoate were identified by gas chromatography-mass spectrometry in comparison with standards. The present results suggest that [1-13C]leucine can participate to the coordination sphere of (Fe2+)-porphyrin, with a caged process of the hydroxyl radicals which cannot get out of the coordination sphere. PMID:9680180

  5. Synthesis and characterization of novel, optically active polyamides derived from S-valine natural amino acid and bulky anthracenic side chain.

    PubMed

    Mallakpour, Shadpour; Mirkarimi, Fatemeh

    2010-11-01

    This is the first description of the application of molten tetrabutylammonium bromide (TBAB) in the presence of triphenyl phosphite (TPP) for the synthesis of novel polyamides (PAs). Monomer diacid, 5-[(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)-3-methylbutanoylamino]isophthalic acid (4), having anthracenic and amino acid S-valine pendant group, was synthesized in four steps. Several novel, optically active PAs were prepared by the condensation of synthesized diacid monomer 4 with various aromatic diamines using two different techniques: a mixture of N-methyl-2-pyrrolidone (NMP)/TPP/pyridine/calcium chloride (method I) and combination of TPP with TBAB (method II). The main goal of the present paper was to prepare novel PAs in a green media by removal of toxic reagents. Therefore, TBAB/TPP was used as a novel, easy, safe and eco-friendly method for the preparation of aromatic PAs. This method is compared with the polymerization reaction under conventional solvent and in the case of TBAB as a new method, higher yields, inherent viscosities and thermally stable of PAs are gained. The resulting polymers showed good solubility in polar aprotic solvents such as dimethyl sulfoxide, NMP, N,N-dimethylacetamide and N,N-dimethylformamide. These polymers are characterized with respect to chemical structure and purity by means of specific rotation experiments, FT-IR, 1H NMR spectroscopy techniques and elemental analysis. The obtained PAs exhibit good thermal stability up to 335°C for 10% weight loss in nitrogen atmosphere and glass transition temperatures fell in the rang of 177-185°C. PMID:20352462

  6. Forced Ambiguity of the Leucine Codons for Multiple-Site-Specific Incorporation of a Noncanonical Amino Acid

    PubMed Central

    Kwon, Inchan; Choi, Eun Sil

    2016-01-01

    Multiple-site-specific incorporation of a noncanonical amino acid into a recombinant protein would be a very useful technique to generate multiple chemical handles for bioconjugation and multivalent binding sites for the enhanced interaction. Previously combination of a mutant yeast phenylalanyl-tRNA synthetase variant and the yeast phenylalanyl-tRNA containing the AAA anticodon was used to incorporate a noncanonical amino acid into multiple UUU phenylalanine (Phe) codons in a site-specific manner. However, due to the less selective codon recognition of the AAA anticodon, there was significant misincorporation of a noncanonical amino acid into unwanted UUC Phe codons. To enhance codon selectivity, we explored degenerate leucine (Leu) codons instead of Phe degenerate codons. Combined use of the mutant yeast phenylalanyl-tRNA containing the CAA anticodon and the yPheRS_naph variant allowed incorporation of a phenylalanine analog, 2-naphthylalanine, into murine dihydrofolate reductase in response to multiple UUG Leu codons, but not to other Leu codon sites. Despite the moderate UUG codon occupancy by 2-naphthylalaine, these results successfully demonstrated that the concept of forced ambiguity of the genetic code can be achieved for the Leu codons, available for multiple-site-specific incorporation. PMID:27028506

  7. Valine radiolysis by MeV ions

    NASA Astrophysics Data System (ADS)

    Da Silveira, Enio

    2016-07-01

    Valine, (CH3)2 CHCH (NH2) COOH, is a protein amino acid that has been identified in extraterrestrial environments and in the Murchison meteorite [1]. The knowledge of half-lives of small organic molecules under ionizing radiation is important for the setup of models describing the spread out of prebiotics across the Solar System or the Galaxy. We have investigated typical effects of MeV cosmic ray ions on prebiotic molecules in laboratory by impinging ions produced by the PUC-Rio Van de Graaff accelerator. Pure valine films, deposited by evaporation on KBr substrates, were irradiated by H ^{+}, He ^{+} and N ^{+} ion beams, from 0.5 to 1.5 MeV and up to a fluence of 10 ^{15} projectiles/cm ^{2}. The sample temperature was varied from 10 K to 300 K. The irradiation was interrupted several times for Mid-FTIR analysis of the sample. The main findings are: 1- The column density of the valine decreases exponentially with fluence. 2- In some cases, a second exponential appears in the beginning of irradiation; this feature has been attributed to sample compaction by the ion beam [2]. 3- Destruction cross sections of valine are in the 10 ^{-15} cm ^{2} range, while compaction cross sections are in the 10 ^{-14} cm ^{2} range. 4- Destruction cross section increases with the stopping power of the beam and also with the sample temperature. 5- Surprisingly, during the radiolysis of valine, just CO _{2} is seen by as a daughter molecule formed in the bulk. 6- After long beam fluence, also a CO peak appears in the infrared spectrum; this species is however interpreted as a fragment of the formed CO2 molecules. 7- Considering the flux ratio between laboratory experiments and actual galactic cosmic rays, half-life of valine is predicted for ISM conditions [3]. This work on pure valine is the first measurement of a series. New experiments are planned for determining cross sections of valine dissolved in H _{2}O or CO _{2}, inspired by the study performed for glycine [4]. [1] P

  8. Leucine metabolism in stable cirrhosis.

    PubMed

    Mullen, K D; Denne, S C; McCullough, A J; Savin, S M; Bruno, D; Tavill, A S; Kalhan, S C

    1986-01-01

    Alterations in protein and amino acid metabolism have been postulated to explain the frequent observations of muscle wasting and decreased plasma branched-chain amino acid concentrations in cirrhosis. In order to investigate the changes in protein metabolism, we have measured the rates of leucine turnover and oxidation in six stable, biopsy-proven cirrhotics and six age and sex-matched healthy control subjects after an overnight fast, using [1-13C]leucine tracer. Following a primed constant-rate infusion of [1-13C]leucine, the 13C enrichments of plasma leucine and expired CO2 were used to estimate leucine turnover and oxidation, respectively. Fat-free body mass was estimated from the measurements of total body water as quantified by H2[18O] tracer dilution. The rates of CO2 production and oxygen consumption were measured hourly during the study period, using open-circuit respiratory calorimetry. Urinary urea, ammonia and total nitrogen excretion rates were quantified from timed urine samples. Even though the plasma leucine levels were lower in cirrhotics as compared with controls (100.5 +/- 17.1 vs. 138.3 +/- 20.4 mumoles per liter, mean +/- S.D., p less than 0.001), the rates of leucine turnover were not significantly different in the two groups (89.4 +/- 19.0 vs. 87.8 +/- 19.0 mumoles per kg X hr). In contrast, the rates of leucine oxidation were significantly reduced in cirrhosis (8.1 +/- 2.5 vs. 12.7 +/- 3.1 mumoles per kg X hr, p less than 0.01). When all subjects were considered, the leucine oxidation rate was correlated with plasma leucine concentration (r = 0.62, p less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3089896

  9. Triennial growth symposium: Leucine acts as a nutrient signal to stimulate protein synthesis in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The postprandial increases in AA and insulin independently stimulate protein synthesis in skeletal muscle of piglets. Leucine is an important mediator of the response to AA. We have shown that the postprandial increase in leucine, but not isoleucine or valine, acutely stimulates muscle protein synth...

  10. Abiotic Formation of Valine Peptides Under Conditions of High Temperature and High Pressure

    NASA Astrophysics Data System (ADS)

    Furukawa, Yoshihiro; Otake, Tsubasa; Ishiguro, Takato; Nakazawa, Hiromoto; Kakegawa, Takeshi

    2012-12-01

    We investigated the oligomerization of solid valine and the stabilities of valine and valine peptides under conditions of high temperature (150-200 °C) and high pressure (50-150 MPa). Experiments were performed under non-aqueous condition in order to promote dehydration reaction. After prolonged exposure of monomeric valine to elevated temperatures and pressures, the products were analyzed by liquid chromatography mass spectrometry comparing their retention times and masses. We identified linear peptides that ranged in size from dimer to hexamer, as well as a cyclic dimer. Previous studies that attempted abiotic oligomerization of valine in the absence of a catalyst have never reported valine peptides larger than a dimer. Increased reaction temperature increased the dissociative decomposition of valine and valine peptides to products such as glycine, β-alanine, ammonia, and amines by processes such as deamination, decarboxylation, and cracking. The amount of residual valine and peptide yields was greater at higher pressures at a given temperature, pressure, and reaction time. This suggests that dissociative decomposition of valine and valine peptides is reduced by pressure. Our findings are relevant to the investigation of diagenetic processes in prebiotic marine sediments where similar pressures occur under water-poor conditions. These findings also suggest that amino acids, such as valine, could have been polymerized to peptides in deep prebiotic marine sediments within a few hundred million years.

  11. Supplementation of a suboptimal protein dose with leucine or essential amino acids: effects on myofibrillar protein synthesis at rest and following resistance exercise in men

    PubMed Central

    Churchward-Venne, Tyler A; Burd, Nicholas A; Mitchell, Cameron J; West, Daniel W D; Philp, Andrew; Marcotte, George R; Baker, Steven K; Baar, Keith; Phillips, Stuart M

    2012-01-01

    Leucine is a nutrient regulator of muscle protein synthesis by activating mTOR and possibly other proteins in this pathway. The purpose of this study was to examine the role of leucine in the regulation of human myofibrillar protein synthesis (MPS). Twenty-four males completed an acute bout of unilateral resistance exercise prior to consuming either: a dose (25 g) of whey protein (WHEY); 6.25 g whey protein with total leucine equivalent to WHEY (LEU); or 6.25 g whey protein with total essential amino acids (EAAs) equivalent to WHEY for all EAAs except leucine (EAA-LEU). Measures of MPS, signalling through mTOR, and amino acid transporter (AAT) mRNA abundance were made while fasted (FAST), and following feeding under rested (FED) and post-exercise (EX-FED) conditions. Leucinaemia was equivalent between WHEY and LEU and elevated compared to EAA-LEU (P = 0.001). MPS was increased above FAST at 1–3 h post-exercise in both FED (P < 0.001) and EX-FED (P < 0.001) conditions with no treatment effect. At 3–5 h, only WHEY remained significantly elevated above FAST in EX-FED (WHEY 184%vs. LEU 55% and EAA-LEU 35%; P = 0.036). AAT mRNA abundance was increased above FAST after feeding and exercise with no effect of leucinaemia. In summary, a low dose of whey protein supplemented with leucine or all other essential amino acids was as effective as a complete protein (WHEY) in stimulating postprandial MPS; however only WHEY was able to sustain increased rates of MPS post-exercise and may therefore be most suited to increase exercise-induced muscle protein accretion. PMID:22451437

  12. Direct Analysis of Leucine and Its Metabolites β-Hydroxy-β-methylbutyric Acid, α-Ketoisocaproic Acid, and α-Hydroxyisocaproic Acid in Human Breast Milk by Liquid Chromatography-Mass Spectrometry.

    PubMed

    Ehling, Stefan; Reddy, Todime M

    2015-09-01

    A direct, quantitative, and confirmatory method based on stable isotope dilution liquid chromatography-mass spectrometry was developed and validated for the analysis of leucine and metabolites β-hydroxy-β-methylbutyric acid (HMB), α-ketoisocaproic acid (KIC), and α-hydroxyisocaproic acid (HICA) in human breast milk. Chromatographic resolution was achieved between isobaric leucine and isoleucine. Accuracy and intermediate precision were 89-117% and <10% relative standard deviation (RSD) across three validation runs. Limits of quantitation for HMB, KIC, HICA, and leucine in human breast milk were 20 μg/L, 20 μg/L, 10 μg/L, and 1 mg/L. Measured concentrations of HMB, KIC, HICA, and free leucine in human breast milk from six donors at various stages of lactation were 42-164 μg/L, < 20-1057 μg/L, < 10 μg/L, and 2.1-88.5 mg/L. HMB and KIC were confirmed in human breast milk by orthogonal hydrophilic interaction chromatography (HILIC). This work provides a tool for further study of human breast milk composition and its effect on protein turnover in developing infants. PMID:26271627

  13. Altered regulation of isoleucine-valine biosynthesis in a hisW mutant of Salmonella typhimurium.

    PubMed

    Davis, L; Williams, L S

    1982-08-01

    Control of isoleucine-valine biosynthesis was examined in the cold-sensitive hisW3333 mutant strain of Salmonella typhimurium. During growth at the permissive temperature (37 degrees C), the isoleucine-valine (ilv) biosynthetic enzyme levels of the hisW mutant were two- to fourfold below these levels in an isogenic hisW+ strain. Upon a reduction in growth temperature to partially permissive (30 degrees C), the synthesis of these enzymes in the hisW mutant was further reduced. However, synthesis of the ilv enzymes was responsive to the repression signal(s) caused by the addition of excess amounts of isoleucine, valine, and leucine to the hisW mutants. Such a "super-repressed" phenotype as that observed in this hisW mutant is similar to that previously shown for the hisU1820 mutant, but was different from the regulatory response of the hisT1504 mutant strain. Moreover, by the use of growth-rate-limiting amounts of the branched-chain amino acids, it was shown that this hisW mutant generally did not increase the synthesis of the ilv enzymes as did the hisW+ strain. Overall, these results are in agreement with the hypothesis that the hisW mutant is less responsive to ilv specific attenuation control than is the hisW+ strain and suggest that this limited regulatory response is due to an alteration in the amount or structure of an element essential to attenuation control of the ilv operons. PMID:7047499

  14. Leucine aminopeptidase blood test

    MedlinePlus

    Serum leucine aminopeptidase ... Leucine aminopeptidase is a type of protein called an enzyme . This enzyme is normally found in cells ... check if your liver is damaged. Too much leucine aminopeptidase is released into your blood when you ...

  15. Enantioselective Synthesis of Quaternary α-Amino Acids via l-tert-Leucine-Derived Squaramide-Catalyzed Conjugate Addition of α-Nitrocarboxylates to Enones.

    PubMed

    Bera, Kalisankar; Satam, Nishikant S; Namboothiri, Irishi N N

    2016-07-01

    Enantioselective Michael addition of tertiary α-nitroesters to β-unsubstituted vinyl ketones has been carried out in the presence of an l-tert-leucine-derived squaramide as organocatalyst. The products, quaternary α-nitroesters, were formed in excellent yield and moderate to good ee's in most cases. Scale-up of the reaction and synthetic applications of the products, including transformation to representative quaternary α-amino acids, have also been demonstrated. PMID:27244116

  16. A Heterospecific Leucine Zipper Tetramer

    SciTech Connect

    Deng, Y.; Liu, J; Zheng, Q; Li, Q; Kallenbach, N; Lu, M

    2008-01-01

    Protein-protein interactions dictate the assembly of the macromolecular complexes essential for functional networks and cellular behavior. Elucidating principles of molecular recognition governing important interfaces such as coiled coils is a challenging goal for structural and systems biology. We report here that two valine-containing mutants of the GCN4 leucine zipper that fold individually as four-stranded coiled coils associate preferentially in mixtures to form an antiparallel, heterotetrameric structure. X-ray crystallographic analysis reveals that the coinciding hydrophobic interfaces of the hetero- and homotetramers differ in detail, explaining their partnering and structural specificity. Equilibrium disulfide exchange and thermal denaturation experiments show that the 50-fold preference for heterospecificity results from a combination of preferential packing and hydrophobicity. The extent of preference is sensitive to the side chains comprising the interface. Thus, heterotypic versus homotypic interaction specificity in coiled coils reflects a delicate balance in complementarity of shape and chemistry of the participating side chains.

  17. Determination of free D-proline and D-leucine in the brains of mutant mice lacking D-amino acid oxidase activity.

    PubMed

    Hamase, K; Inoue, T; Morikawa, A; Konno, R; Zaitsu, K

    2001-11-15

    A new procedure to accurately measure a trace amount of d-proline in biological samples has been developed. This D-amino acid was derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole and was determined by a column-switching HPLC system, a combination of a micro-ODS column and a chiral column. The detection limit for D-proline spiked in a mouse cerebrum sample is 1 fmol (injection amount, S/N = 3). Within-day precision and day-to-day precision obtained for spiked d-proline (10 fmol) are 2.14 and 5.35% (RSD), respectively. Using the new method, the amount of free D-proline in eight brain regions and sera of mutant ddY/DAO- mice, lacking D-amino acid oxidase activity, and control ddY/DAO+ mice was determined. The amount of free D-leucine was also investigated. The amount and distribution of D-proline in the brains of ddY/DAO+ mice and ddY/DAO- mice are almost the same, and relatively high amounts of D-proline have been observed in the pituitary gland and in the pineal gland. On the other hand, the amount of D-leucine is different between the two strains. In the brains of ddY/DAO+ mice, a relatively high amount of D-leucine has been observed in the pineal gland compared with other regions. In the brains of ddY/DAO- mice, D-leucine amounts are approximately 10 times higher than those obtained in ddY/DAO+ mice and regional difference has not been observed, while the amounts of L-proline and L-leucine are not significantly different between the two strains. In the serum, the amounts of both free D-proline and d-leucine are significantly higher in the ddY/DAO- mice than those obtained in ddY/DAO+ mice. PMID:11700980

  18. Structural insights into chaperone-activity enhancement by a K354E mutation in tomato acidic leucine aminopeptidase.

    PubMed

    DuPrez, Kevin T; Scranton, Melissa A; Walling, Linda L; Fan, Li

    2016-05-01

    Tomato plants express acidic leucine aminopeptidase (LAP-A) in response to various environmental stressors. LAP-A not only functions as a peptidase for diverse peptide substrates, but also displays chaperone activity. A K354E mutation has been shown to abolish the peptidase activity but to enhance the chaperone activity of LAP-A. To better understand this moonlighting function of LAP-A, the crystal structure of the K354E mutant was determined at 2.15 Å resolution. The structure reveals that the K354E mutation destabilizes an active-site loop and causes significant rearrangement of active-site residues, leading to loss of the catalytic metal-ion coordination required for the peptidase activity. Although the mutant was crystallized in the same hexameric form as wild-type LAP-A, gel-filtration chromatography revealed an apparent shift from the hexamer to lower-order oligomers for the K354E mutant, showing a mixture of monomers to trimers in solution. In addition, surface-probing assays indicated that the K354E mutant has more accessible hydrophobic areas than wild-type LAP-A. Consistently, computational thermodynamic estimations of the interfaces between LAP-A monomers suggest that increased exposure of hydrophobic surfaces occurs upon hexamer breakdown. These results suggest that the K354E mutation disrupts the active-site loop, which also contributes to the hexameric assembly, and destabilizes the hexamers, resulting in much greater hydrophobic areas accessible for efficient chaperone activity than in the wild-type LAP-A. PMID:27139632

  19. Proline-, glutamic acid-, and leucine-rich protein 1 mediates estrogen rapid signaling and neuroprotection in the brain

    PubMed Central

    Sareddy, Gangadhara R.; Zhang, Quanguang; Wang, Ruimin; Scott, Erin; Zou, Yi; O'Connor, Jason C.; Chen, Yidong; Dong, Yan; Vadlamudi, Ratna K.; Brann, Darrell

    2015-01-01

    17-β estradiol (E2) has been implicated as neuroprotective in a variety of neurodegenerative disorders. However, the underlying mechanism remains unknown. Here, we provide genetic evidence, using forebrain-specific knockout (FBKO) mice, that proline-, glutamic acid-, and leucine-rich protein 1 (PELP1), an estrogen receptor coregulator protein, is essential for the extranuclear signaling and neuroprotective actions of E2 in the hippocampal CA1 region after global cerebral ischemia (GCI). E2-mediated extranuclear signaling (including activation of extracellular signal-regulated kinase and Akt) and antiapoptotic effects [such as attenuation of JNK signaling and increase in phosphorylation of glycogen synthase kinase-3β (GSK3β)] after GCI were compromised in PELP1 FBKO mice. Mechanistic studies revealed that PELP1 interacts with GSK3β, E2 modulates interaction of PELP1 with GSK3β, and PELP1 is a novel substrate for GSK3β. RNA-seq analysis of control and PELP1 FBKO mice after ischemia demonstrated alterations in several genes related to inflammation, metabolism, and survival in PELP1 FBKO mice, as well as a significant reduction in the activation of the Wnt/β-catenin signaling pathway. In addition, PELP1 FBKO studies revealed that PELP1 is required for E2-mediated neuroprotection and for E2-mediated preservation of cognitive function after GCI. Collectively, our data provide the first direct in vivo evidence, to our knowledge, of an essential role for PELP1 in E2-mediated rapid extranuclear signaling, neuroprotection, and cognitive function in the brain. PMID:26627258

  20. 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

  1. Leucine-Enriched Essential Amino Acids Augment Mixed Protein Synthesis, But Not Collagen Protein Synthesis, in Rat Skeletal Muscle after Downhill Running.

    PubMed

    Kato, Hiroyuki; Suzuki, Hiromi; Inoue, Yoshiko; Suzuki, Katsuya; Kobayashi, Hisamine

    2016-01-01

    Mixed and collagen protein synthesis is elevated for as many as 3 days following exercise. Immediately after exercise, enhanced amino acid availability increases synthesis of mixed muscle protein, but not muscle collagen protein. However, the potential for synergic effects of amino acid ingestion with exercise on both mixed and collagen protein synthesis remains unclear. We investigated muscle collagen protein synthesis in rats following post-exercise ingestion of leucine-enriched essential amino acids. We determined fractional protein synthesis rates (FSR) at different time points following exercise. Mixed protein and collagen protein FSRs in skeletal muscle were determined by measuring protein-bound enrichments of hydroxyproline and proline, and by measuring the intracellular enrichment of proline, using injections of flooding d₃-proline doses. A leucine-enriched mixture of essential amino acids (or distilled water as a control) was administrated 30 min or 1 day post-exercise. The collagen protein synthesis in the vastus lateralis was elevated for 2 days after exercise. Although amino acid administration did not increase muscle collagen protein synthesis, it did lead to augmented mixed muscle protein synthesis 1 day following exercise. Thus, contrary to the regulation of mixed muscle protein synthesis, muscle collagen protein synthesis is not affected by amino acid availability after damage-inducing exercise. PMID:27367725

  2. Leucine-Enriched Essential Amino Acids Augment Mixed Protein Synthesis, But Not Collagen Protein Synthesis, in Rat Skeletal Muscle after Downhill Running

    PubMed Central

    Kato, Hiroyuki; Suzuki, Hiromi; Inoue, Yoshiko; Suzuki, Katsuya; Kobayashi, Hisamine

    2016-01-01

    Mixed and collagen protein synthesis is elevated for as many as 3 days following exercise. Immediately after exercise, enhanced amino acid availability increases synthesis of mixed muscle protein, but not muscle collagen protein. However, the potential for synergic effects of amino acid ingestion with exercise on both mixed and collagen protein synthesis remains unclear. We investigated muscle collagen protein synthesis in rats following post-exercise ingestion of leucine-enriched essential amino acids. We determined fractional protein synthesis rates (FSR) at different time points following exercise. Mixed protein and collagen protein FSRs in skeletal muscle were determined by measuring protein-bound enrichments of hydroxyproline and proline, and by measuring the intracellular enrichment of proline, using injections of flooding d3-proline doses. A leucine-enriched mixture of essential amino acids (or distilled water as a control) was administrated 30 min or 1 day post-exercise. The collagen protein synthesis in the vastus lateralis was elevated for 2 days after exercise. Although amino acid administration did not increase muscle collagen protein synthesis, it did lead to augmented mixed muscle protein synthesis 1 day following exercise. Thus, contrary to the regulation of mixed muscle protein synthesis, muscle collagen protein synthesis is not affected by amino acid availability after damage-inducing exercise. PMID:27367725

  3. Acidic leucine-rich nuclear phosphoprotein 32 family member B (ANP32B) contributes to retinoic acid-induced differentiation of leukemic cells

    SciTech Connect

    Yu, Yun; Shen, Shao-Ming; Zhang, Fei-Fei; Wu, Zhao-Xia; Han, Bin; Wang, Li-Shun

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer ANP32B was down-regulated during ATRA-induced leukemic cell differentiation. Black-Right-Pointing-Pointer Knockdown of ANP32B enhanced ATRA-induced leukemic cell differentiation. Black-Right-Pointing-Pointer Ectopic expression of ANP32B inhibited ATRA-induced leukemic cell differentiation. Black-Right-Pointing-Pointer ANP32B inhibited ATRA activated transcriptional activity of RAR{alpha}. -- Abstract: The acidic leucine-rich nuclear phosphoprotein 32B (ANP32B) is a member of a conserved superfamily of nuclear proteins whose functions are largely unknown. In our previous work, ANP32B was identified as a novel direct substrate for caspase-3 and acted as a negative regulator for leukemic cell apoptosis. In this work, we provided the first demonstration that ANP32B expression was down-regulated during differentiation induction of leukemic cells by all-trans retinoic acid (ATRA). Knockdown of ANP32B expression by specific shRNA enhanced ATRA-induced leukemic cell differentiation, while ectopic expression of ANP32B attenuated it, indicating an inhibitory role of ANP32B against leukemic cell differentiation. Furthermore, luciferase reporter assay revealed that ANP32B might exert this role through inhibiting the ATRA dependent transcriptional activity of retinoic acid receptor (RAR{alpha}). These data will shed new insights into understanding the biological functions of ANP32B protein.

  4. Prebiotic Synthesis of Hydrophobic and Protein Amino Acids

    PubMed Central

    Ring, David; Wolman, Yecheskel; Friedmann, Nadav; Miller, Stanley L.

    1972-01-01

    The formation of amino acids by the action of electric discharges on a mixture of methane, nitrogen, and water with traces of ammonia was studied in detail. The presence of glycine, alanine, α-amino-n-butyric acid, α-aminoisobutyric acid, valine, norvaline, isovaline, leucine, isoleucine, alloisoleucine, norleucine, proline, aspartic acid, glutamic acid, serine, threonine, allothreonine, α-hydroxy-γ-aminobutyric acid, and α,γ-diaminobutyric acid was confirmed by ion-exchange chromatography and gas chromatography-mass spectrometry. All of the primary α-amino acids found in the Murchison Meteorite have been synthesized by this electric discharge experiment. PMID:4501592

  5. Repression and inhibition of transport systems for branched-chain amino acids in Salmonella typhimurium.

    PubMed

    Kiritani, K; Ohnishi, K

    1977-02-01

    Kinetics of the transport systems common for entry of L-isoleucine, L-leucine, and L-valine in Salmonella typhimurium LT2 have been analyzed as a function of substrateconcentration in the range of 0.5 to 45 muM. The systems of transport mutants, KA203 (ilvT3) and KA204 (ilvT4), are composed of two components; apparent Km values for uptake of isoleucine, leucine, and valine by the low Km component are 2 muM, 2 to 3 muM, and 1 muM, respectively, and by the high Km component 30 muM, 20 to 40 muM, and 0.1 mM, respectively. The transport system(s) of the wild type has not been separated into components but rather displays single Km values of 9 muM for isoleucine, 10 muM for leucine, and 30 muM for valine. The transport activity of the wild type was repressed by L-leucine, alpha ketoisocaproate, glycyl-L-isoleucine, glycyl-L-leucine, and glycyl-L-methionine. That for the transport mutants was repressed by L-alanine, L-isoleucine, L-methionine, L-valine, alpha-ketoisovalerate, alpha-keto-beta-methylvalerate, glycyl-L-alanine, glycyl-L-threonine, and glycyl-L-valine, in addition to the compounds described above. Repression of the mutant transport systems resulted in disappearance of the low Km component for valine uptake, together with a decrease in Vmax of the high Km component; the kinetic analysis with isoleucine and leucine as substrates was not possible because of poor uptake. The maximum reduction of the transport activity for isoleucine was obtained after growing cells for two to three generations in a medium supplemented with repressor, and for the depression, protein synthesis was essential after removal of the repressor. The transport activity for labeled isoleucine in the transport mutant and wild-type strains was inhibited by unlabeled L-alanine, L-cysteine, L-isoleucine, L-leucine, L-methionine, L-threonine, and L-valine. D-Amino acids neither repressed nor inhibited the transport activity of cells for entry of isoleucine. PMID:320186

  6. The basic leucine zipper transcription factor ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 is an important transcriptional regulator of abscisic acid-dependent grape berry ripening processes.

    PubMed

    Nicolas, Philippe; Lecourieux, David; Kappel, Christian; Cluzet, Stéphanie; Cramer, Grant; Delrot, Serge; Lecourieux, Fatma

    2014-01-01

    In grape (Vitis vinifera), abscisic acid (ABA) accumulates during fruit ripening and is thought to play a pivotal role in this process, but the molecular basis of this control is poorly understood. This work characterizes ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 (VvABF2), a grape basic leucine zipper transcription factor belonging to a phylogenetic subgroup previously shown to be involved in ABA and abiotic stress signaling in other plant species. VvABF2 transcripts mainly accumulated in the berry, from the onset of ripening to the harvesting stage, and were up-regulated by ABA. Microarray analysis of transgenic grape cells overexpressing VvABF2 showed that this transcription factor up-regulates and/or modifies existing networks related to ABA responses. In addition, grape cells overexpressing VvABF2 exhibited enhanced responses to ABA treatment compared with control cells. Among the VvABF2-mediated responses highlighted in this study, the synthesis of phenolic compounds and cell wall softening were the most strongly affected. VvABF2 overexpression strongly increased the accumulation of stilbenes that play a role in plant defense and human health (resveratrol and piceid). In addition, the firmness of fruits from tomato (Solanum lycopersicum) plants overexpressing VvABF2 was strongly reduced. These data indicate that VvABF2 is an important transcriptional regulator of ABA-dependent grape berry ripening. PMID:24276949

  7. Suppressors of a genetic regulatory mutation affecting isoleucine-valine biosynthesis in Escherichia coli K-12.

    PubMed Central

    Hahn, J E; Calhoun, D H

    1978-01-01

    Escherichia coli K-12 mutant PS187 carries a mutation, ilvA538, in the structural gene for the biosynthetic L-threonine deaminase that leads to a leucine-sensitive growth phenotype, an isoleucine- and leucine-hypersensitive L-threonine deaminase, and pleiotropic effects resulting in abnormally low and invariant expression of some of the isoleucine-valine biosynthetic enzymes. Fifty-eight derivatives of strain PS187 were isolated as resistant to growth inhibition by leucine, by valine, or by valine plus glycly-valine and were biochemically, genetically, and physiologically characterized. All of these derivatives produced the feedback-hypersensitive L-threonine deaminase, and thus presumably possess the ilvA538 allele of the parent strain. Elevated synthesis of L-threonine deaminase was observed in 41 of the 58 isolates. Among 18 strains analyzed genetically, only those with mutations linked to the ilv gene clusters at 83 min produced elevated levels of L-threonine deaminase. One of the strains, MSR91, isolated as resistant to valine plus glycyl-valine, was chosen for more detailed study. The locus in strain MSR91 conferring resistance was located in four factor crosses between ilvE and rbs, and is in or near the ilvO gene postulated to be a site controlling the expression of the ilvEDA genes. Synthesis of the ilvEDA gene products in strain MSR91 is constitutive and derepressed approximately 200-fold relative to the parent strain, indicating that the genetic regulatory effects of the ilvA538 allele have been suppressed. Strain MSR91 should be suitable for use in purification of the ilvA538 gene product, since enzyme synthesis is fully derepressed and the suppressor mutation is clearly not located within the ilvA gene. PMID:361682

  8. Effect of spermine on the uptake of amino acids in Micrococcus lysodeikticus.

    PubMed

    Ariel, M; Grossowicz, N

    1972-08-01

    Spermine inhibited the transport of neutral aliphatic amino acids (valine, leucine, isoleucine, alanine, and glycine) into cells of Micrococcus lysodeikticus. On the other hand, spermine did not affect the uptake of basic (arginine and histidine), acidic (glutamic acid), or aromatic (phenylalanine and tyrosine) amino acids. Inhibition of uptake of the neutral amino acids by spermine is apparently of a noncompetitive nature; the V(max) decreased, whereas the apparent K(m) remained unaltered. The inhibition is most likely due to a specific binding of spermine to the carrier(s) of these amino acids. Related polyamines, spermidine and cadaverine, also caused inhibition of valine uptake, though to a lesser extent; spermidine was less active than spermine, and cadaverine showed the weakest effect of all. Valine, leucine, and isoleucine were transported into M. lysodeikticus cells by a common carrier as evidenced from competition experiments. The uptake of these amino acids is an active process; it was temperature-dependent and inhibited by azide (10(-1)m to 2.5 x 10(-2)m) and dinitrophenol (10(-3)m). The intracellular concentration of valine was 100-fold higher than in the medium. PMID:5053465

  9. Phase Shift of the Circadian Rhythm of Lemna Caused by Pulses of a Leucine Analog, Trifluoroleucine

    PubMed Central

    Kondo, Takao

    1988-01-01

    Pulses of a fluorinated analog of leucine, 5′,5′,5′-trifluoroleucine, reset the phase of the circadian rhythm of K+ uptake in Lemna gibba G3 under continuous light conditions. The trifluoroleucine pulse caused the largest delay phase-shifts during the early subjective phase but it caused only small phase advances. The action of trifluoroleucine was investigated and the following results were obtained. (a) The uptake of trifluoroleucine was essentially the same at all circadian phases, even though phase shifting was dramatically different at different phases. At effective phases, the magnitude of phase shifting was well correlated with the amount of trifluoroleucine taken up by the duckweed. (b) The trifluoroleucine pulse lowered the endogenous content of valine and leucine but these decreases did not correlate with phase shifting. (c) Protein synthesis was not affected by trifluoroleucine pulses which caused large phase shifts. (d) Pulses of 4-azaleucine, a different structural analog of leucine, also caused phase shifting. However, neither the direction nor the effective times of phase shifting were similar to those of trifluoroleucine. Taken together, these results negate the proposition that trifluoroleucine and azaleucine caused phase shift by disturbing amino acid metabolism and/or inhibiting protein synthesis, but they suggest instead that these analogs are incorporated into some protein(s) which are necessary for normal clock operation. PMID:16666410

  10. Transaminase B from Escherichia coli: quaternary structure, amino-terminal sequence, substrate specificity, and absence of a separate valine-alpha-ketoglutarate activity.

    PubMed

    Lee-Peng, F C; Hermodson, M A; Kohlhaw, G B

    1979-08-01

    Transaminase B (branched-chain amino acid aminotransferase, EC 2.6.1.42), the ilvE gene product, was purified to apparent homogeneity from an Escherichia coli K-12 strain which carries the ilvE gene both on the host chromosome and on a plasmid. The oligomeric structure of the enzyme, as determined by analytical ultracentrifugation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was confirmed to be that of a hexamer with a molecular weight of about 182,000 and apparently identical subunits. Cross-linking with dimethylsuberimidate yielded trimers, dimers, and monomers, but essentially no species of higher molecular weight. These results are consistent with a double-trimer arrangement of the subunits in native enzyme. The amino-terminal sequence was found to be: Gly Thr Lys Lys Ala Asp Tyr Ile (Trp) Phe Asn Gly (Thr) (Met) Val. Purified transaminase B catalyzed transamination between alpha-ketoglutarate and l-isoleucine, l-leucine, l-valine, and, to a lesser extent, l-phenylalanine and l-tyrosine, the latter reacting very sluggishly. The enzyme was free of aspartate transaminase and of transaminase C. The apparent K(m) values for the branched-chain alpha-ketoacids were smaller than those for the corresponding amino acids. The lowest K(m) was recorded for dl-alpha-keto-beta-methyl-n-valerate, and the highest was recorded for l-valine. The ratio of the valine- and isoleucine-alpha-ketoglutarate activities did not change significantly during purification, and both activities were quantitatively removed from crude extract by antibody raised against purified transaminase B. These observations argue against the existence of a separate valine-alpha-ketoglutarate transaminase. Anti-E. coli transaminase B antibody cross-reacted with crude extract from Salmonella typhimurium, but not with extract obtained from Pseudomonas aeruginosa. PMID:378964

  11. Association between insulin resistance and plasma amino acid profile in non-diabetic Japanese subjects

    PubMed Central

    Yamada, Chizumi; Kondo, Masumi; Kishimoto, Noriaki; Shibata, Takeo; Nagai, Yoko; Imanishi, Tadashi; Oroguchi, Takashige; Ishii, Naoaki; Nishizaki, Yasuhiro

    2015-01-01

    Aims/Introduction Elevation of the branched-chain amino acids (BCAAs), valine, leucine and isoleucine; and the aromatic amino acids, tyrosine and phenylalanine, has been observed in obesity-related insulin resistance. However, there have been few studies on Asians, who are generally less obese and less insulin-resistant than Caucasian or African-Americans. In the present study, we investigated the relationship between homeostasis model assessment of insulin resistance (HOMA-IR) and plasma amino acid concentration in non-diabetic Japanese participants. Materials and Methods A total of 94 healthy men and women were enrolled, and plasma amino acid concentration was measured by liquid chromatography/mass spectrometry after overnight fasting. The associations between HOMA-IR and 20 amino acid concentrations, and anthropometric and clinical parameters of lifestyle-related diseases were evaluated. Results The mean age and body mass index were 40.1 ± 9.6 years and 22.7 ± 3.9, respectively. Significantly positive correlations were observed between HOMA-IR and valine, isoleucine, leucine, tyrosine, phenylalanine and total BCAA concentration. Compared with the HOMA-IR ≤ 1.6 group, the HOMA-IR > 1.6 group showed significantly exacerbated anthropometric and clinical parameters, and significantly elevated levels of valine, isoleucine, leucine, tyrosine, phenylalanine and BCAA. Conclusions The present study shows that the insulin resistance-related change in amino acid profile is also observed in non-diabetic Japanese subjects. These amino acids include BCAAs (valine, isoleucine and leucine) and aromatic amino acids (tyrosine and phenylalanine), in agreement with previous studies carried out using different ethnic groups with different degrees of obesity and insulin resistance. PMID:26221519

  12. Leucine aminopeptidase - urine

    MedlinePlus

    Leucine aminopeptidase is a type of protein called an enzyme. It is normally found in liver cells ... Increased levels of leucine aminopeptidase can be seen in ... Hepatitis Liver cancer Liver ischemia (reduced blood flow to the ...

  13. Leucine aminopeptidase - urine

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003617.htm Leucine aminopeptidase - urine To use the sharing features on this page, please enable JavaScript. Leucine aminopeptidase is a type of protein called an ...

  14. Utilization of α-Keto and α-Hydroxy Analogues of Valine by the Growing Rat

    PubMed Central

    Chawla, Rajender K.; Rudman, Daniel

    1974-01-01

    When 70-80-g male albino rats eat a diet furnishing daily requirement of valine for optimal growth (70 μmol/g) and all other nutrients (“complete diet”), they gain weight at an average rate of 3.0 g/100 g body wt/day. When valine is removed, they lose weight at an average 2.1 g/100 g body wt/day. The growth retardation is improved or corrected by adding valine to the diet, daily weight gain being proportional to dietary valine content over a range of 0-70 μmol/g. Addition of α-ketoisovaleric acid instead of valine to the valine-free diet also improves or corrects the growth failure. Percent efficiency of α-ketoisovaleric acid as a substitute for valine was calculated as: 100 × (micromole valine per gram diet required to produce specified growth response)/(micromole α-ketoisovaleric acid per gram diet required to produce the same response). Efficiency of the substitution is inversely related to dietary content of the keto analogue, being 80% when diet contains 17.5 μmol/g (molar equivalent of ¼ the daily requirement of valine), and 37% when diet provides 140 μmol/g (molar equivalent of twice the daily requirement of valine). α-Hydroxyisovaleric acid also substitutes for valine. Efficiency of the substitution at the single ration tested, 70 μmol/g diet, is 45%, similar to that for the keto analogue under the same conditions. When [1-14C]α-ketoisovaleric acid is injected intravenously, 30-80% of the administered radioactivity is exhaled as 14CO2 within 24 h. This finding suggests that inefficiency of α-ketoisovaleric acid as a substitute for valine results in part from degradation of the keto acid to isobutyric acid by branched chain dehydrogenase-decarboxylase. Oral administration of neomycin, polymyxin, and bacitracin reduces efficiency of α-ketoisovaleric acid as a substitute for valine by ¼-½. This effect suggests that transamination of the keto acid may be performed in part by gastrointestinal microbes. PMID:4367888

  15. 21 CFR 582.5925 - Valine.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Valine. 582.5925 Section 582.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... § 582.5925 Valine. (a) Product. Valine (L- and DL-forms). (b) Conditions of use. This substance...

  16. 21 CFR 582.5925 - Valine.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Valine. 582.5925 Section 582.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... § 582.5925 Valine. (a) Product. Valine (L- and DL-forms). (b) Conditions of use. This substance...

  17. 21 CFR 582.5925 - Valine.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Valine. 582.5925 Section 582.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... § 582.5925 Valine. (a) Product. Valine (L- and DL-forms). (b) Conditions of use. This substance...

  18. 21 CFR 582.5925 - Valine.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Valine. 582.5925 Section 582.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... § 582.5925 Valine. (a) Product. Valine (L- and DL-forms). (b) Conditions of use. This substance...

  19. 21 CFR 582.5925 - Valine.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Valine. 582.5925 Section 582.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... § 582.5925 Valine. (a) Product. Valine (L- and DL-forms). (b) Conditions of use. This substance...

  20. L-Leucine prevents ammonia-induced changes in glutamate receptors in the brain and in visual evoked potentials in the rabbit.

    PubMed

    Ferenci, P; Pappas, C S; Jones, E A

    1984-01-01

    The effect of L-leucine on glutamate receptors in the brain and on visual evoked potentials was studied in hyperammonemic rabbits. Hyperammonemia was induced by the iv infusion of 2.1 mmol NH4Cl/h over 3 hr. Hyperammonemia was followed by a 116% increase in the specific binding of 3H-glutamate to synaptic membranes prepared from the hippocampus. This increase was due to both an increase in the affinity and in the density of the glutamate receptor. The simultaneous infusion of L-leucine (6.7 mmol/hr) completely prevented the ammonia-induced increase in the specific glutamate binding, whereas L-valine and D-leucine had no effect. Hyperammonemia was also associated with typical, reproducible, and reversible changes in visual evoked potentials. The amplitudes of the first negative and the second positive peak decreased, whereas the latencies of these peaks remained unchanged. The simultaneous infusion of L-leucine completely prevented these changes. These findings indicate (1) that L-leucine prevents ammonia-induced changes in the glutamatergic excitatory neurotransmitter system and (2) that pharmacologic doses of L-leucine modulate the effects of hyperammonemia on central neurotransmission as assessed by visual evoked potentials. A causal relationship between the effects of L-leucine on ammonia-induced changes in glutamate receptors and in visual evoked potentials cannot be inferred with confidence. These findings provide a potential alternative explanation for the apparent beneficial effects of infusions of branched-chain amino acids on hepatic encephalography in patients with chronic liver disease. PMID:6151602

  1. Maintenance valine, isoleucine, and tryptophan requirements for poultry.

    PubMed

    de Lima, M B; Sakomura, N K; Dorigam, J C P; da Silva, E P; Ferreira, N T; Fernandes, J B K

    2016-04-01

    Poultry maintenance requirements for valine, isoleucine, and tryptophan were measured by nitrogen balance using different unit systems. The nitrogen balance trial lasted 5 d with 48 h of fasting (with roosters receiving only water+sucrose) and the last 72 h for feeding and excreta collection. Forty grams of each diet first-limiting in valine, isoleucine, or tryptophan was fed by tube each day (3 d) to give a range of intakes from 0 to 101, 0 to 119, and 0 to 34 mg/kg BW d of valine, isoleucine, and tryptophan, respectively. A nitrogen-free diet containing energy, vitamins, and minerals, meeting the rooster requirements, was offered ad libitum during these three d. To confirm that the amino acids studied were limiting, a treatment was added with a control diet formulated by adding 0.24 g/kg of L-valine, 0.21 g/kg of L-isoleucine, and 0.10 g/kg of L-tryptophan to the diets with lower amino acid level. Excreta were collected during the last 3 d of the balance period and the nitrogen content of the excreta was analyzed. For each amino acid, a linear regression between nitrogen retention (NR) and amino acid intake was performed. The equations from linear regression were: NR=-98.6 (±10.1)+2.4 (±0.2)×Val, NR=-46.9 (±7.1)+2.3 (±0.1)×Ile, NR=-39.5 (±7.7)+7.3 (±0.4)×Trp; where Val, Ile, and Trp are the intakes of valine, isoleucine, and tryptophan in mg/kg body weight per d, respectively. The valine, isoleucine, and tryptophan required to maintain the body at zero NR were calculated to be 41, 20, and 5 mg/kg body weight per d, respectively. For the system unit mg per kg of metabolic weight, the intake of valine, isoleucine, and tryptophan was 59, 32, and 9, respectively. Considering the degree of maturity of the animal and body protein content (BPm (0.73)×u), the amounts of valine, isoleucine, and tryptophan required for maintenance were calculated to be 247, 134, and 37 mg per unit of maintenance protein (BPm (0.73)×u) per d. Maintenance requirement is more

  2. One-step biosynthesis of α-ketoisocaproate from L-leucine by an Escherichia coli whole-cell biocatalyst expressing an L-amino acid deaminase from Proteus vulgaris.

    PubMed

    Song, Yang; Li, Jianghua; Shin, Hyun-dong; Du, Guocheng; Liu, Long; Chen, Jian

    2015-01-01

    This work aimed to develop a whole-cell biotransformation process for the production of α-ketoisocaproate from L-leucine. A recombinant Escherichia coli strain was constructed by expressing an L-amino acid deaminase from Proteus vulgaris. To enhance α-ketoisocaproate production, the reaction conditions were optimized as follows: whole-cell biocatalyst 0.8 g/L, leucine concentration 13.1 g/L, temperature 35 °C, pH 7.5, and reaction time 20 h. Under the above conditions, the α-ketoisocaproate titer reached 12.7 g/L with a leucine conversion rate of 97.8%. In addition, different leucine feeding strategies were examined to increase the α-ketoisocaproate titer. When 13.1 g/L leucine was added at 2-h intervals (from 0 to 22 h, 12 addition times), the α-ketoisocaproate titer reached 69.1 g/L, while the leucine conversion rate decreased to 50.3%. We have developed an effective process for the biotechnological production of α-ketoisocaproate that is more environmentally friendly than the traditional petrochemical synthesis approach. PMID:26217895

  3. E.S.R. of spin-trapped radicals in gamma-irradiated polycrystalline amino acids. Chromatographic separation of radicals.

    PubMed

    Makino, K; Riesz, P

    1982-06-01

    The free radicals produced by gamma-radiolysis of polycrystalline amino acids (L-valine, L-leucine, L-isoleucine and L-proline) at room temperature in the absence of air were investigated by spin trapping with 2-methyl-2-nitrosopropane (MNP). The spin adducts produced by dissolving the irradiated solids in aqueous MNP solutions were separated by high-performance liquid chromatography and then identified by e.s.r. Deamination (ring-opening reaction for L-proline) was observed for all amino acid. For L-valine and L-leucine, H-abstraction from the tertiary carbon in the side chains occurred. For isoleucine, H-abstractions from the alpha-carbon of the amino acid and from a non-terminal carbon in the side chain were found. PMID:6288602

  4. Stereospecificity of amino acid hydroxamate inhibition of aminopeptidases.

    PubMed

    Wilkes, S H; Prescott, J M

    1983-11-25

    Hydroxamates of amino acids and aliphatic acids are effective inhibitors of Aeromonas proteolytica amino-peptidase (EC 3.4.11.10) and of both the cytosolic (EC 3.4.11.1) and microsomal (EC 3.4.11.2) aminopeptidases of swine kidney. Cytosolic leucine aminopeptidase and the Aeromonas enzyme were inhibited to a greater extent by D isomers than by the L enantiomorphs, manganese-activated kidney cytosolic leucine aminopeptidase being inhibited 10 times more effectively by D-leucine and D-valine hydroxamic acids than by the L isomers. The D isomers of these two compounds inhibited Aeromonas aminopeptidase to an even greater extent with Ki values of 2 X 10(-9) and 5 X 10(-9), respectively, whereas the corresponding L isomers were bound 150 times less tightly. With the Aeromonas enzyme, a comparison of inhibition by racemic mixtures with that of the corresponding L isomers indicated that in all cases the contribution of the D isomer was predominant. Isocaproic hydroxamic acid inhibited this enzyme equally well as L-leucine hydroxamic acid, indicating that the amino group orientation in the D isomer contributes to the binding efficacy. Swine kidney microsomal aminopeptidase was also inhibited by D isomers of leucine and valine hydroxamic acids but in contrast to the other two enzymes, the inhibition was 10-fold less than that observed for the corresponding L isomers. Cytosolic leucine aminopeptidase with either 6 g atoms of zinc per mol or 12 g atoms of zinc per mol was inhibited only slightly by any of the hydroxamic acid compounds; evidently enzyme-bound manganese (or magnesium) is specific for hydroxamate binding to this aminopeptidase. PMID:6643439

  5. Efficiency of substitution of 2-ketoisocaproic acid and 2-ketoisovaleric acid in the diet of normal and uremic growing rats.

    PubMed

    Laouari, D; Kamoun, P P; Rocchiccioli, F; Dodu, C; Kleinknecht, C; Broyer, M

    1986-12-01

    Effects of various intakes of the ketoanalogues of leucine (KICA) and valine (KIVA) on growth, nitrogen, and urea excretion were examined and compared to those of an optimal intake (A) of the corresponding amino acids. Diet KICA and KIVA contents varied from 1 to 4 times A. In controls, growth was significantly reduced with equimolar substitution, corrected with twice A, and unchanged at higher levels. Doubling KICA corrected growth except with substantial anorexia. In uremic rats fed KIVA, growth was corrected at twice A. Low-KICA diets reduced plasma-leucine level; higher KICA diets normalized plasma leucine and revealed branched-chain amino acid (BCAA) antagonism. Changes in 2-ketoacids were unrelated to those of BCAA. In uremia, KICA decreased plasma and urinary urea without changing nitrogen retention. Ketoacid substitution for amino acids was 50% efficient in normal rats and not altered by uremia. BCKAs, specifically KICA, could modify urea metabolism. PMID:3788832

  6. 1H nuclear magnetic resonance of modified bases of valine transfer ribonucleic acid (Escherichia coli). A direct monitor of sequential thermal unfolding.

    PubMed

    Kastrup, R V; Schmidt, P G

    1975-08-12

    Proton magnetic resonances at 220 MHz from three nucleotide residues of valine I tRNA (Escherichia coli) serve as intrinsic probes of local molecular structure. Resonances from the methyl group of ribothymidine, the methyl group of N6-methyladenosine, and the C-5 methylene of dihydrouridine monitor separate conformational transitions in the TpsiC, anticodon, and dihydrouridine loops, respectively. As the temperature is raised in a solution containing 0.23 M Na+ and no Mg2+, the dihydrouridine region melts with a Tm of 55 degrees, the anticodon region at 58 degrees, and the TpsiC region at 67 degrees. The dihydrouridine nuclear magnetic resonance (NMR) transition correlates with the major change in absorbance monitored in the uv at 330 nm which is ascribed to structural pertubations near the 4-thiouracil moiety. On the NMR time scale slow exchange is seen throughout the temperature range for dihydrouridine and below the apparent Tm for the ribothymidine methyl group. Chemical shift and line width differences between folded and unfolded forms of the polynucleotide indicate that, in the native structure, ribothymidine is in a highly structured region and N6-methyladenosine is in a somewhat less restricted environment. Narrow line widths for the C-5 methylene triplet are found over the whole temperature range indicating that this base is undergoing rapid internal reorientation relative to the overall macromolecule. PMID:1100098

  7. Gallic acid-l-leucine (GAL) conjugate enhances macrophage phagocytosis via inducing leukotriene B4 12-hydroxydehydrogenase (LTB4DH) expression.

    PubMed

    Cheng, Yuanyuan; Tse, Hung-Fat; Li, Xuechen; Han, Yifan; Rong, Jianhui

    2016-06-01

    Timely clearance of apoptotic cells is an important step in the resolution of ongoing inflammation and the restoration of tissue integrity and function after acute myocardial infarction. Natural products gallic acid and l-leucine are well-documented for anti-inflammatory and anabolic effects. We synthesized gallic acid-l-leucine (GAL) conjugate via direct coupling gallic acid and l-leucine. The aim of the present study was to investigate the effect of GAL conjugate on the phagocytotic activity of macrophages. By using murine macrophage cell line RAW264.7 as an in vitro model, we evaluated the effect of GAL conjugate on the phagocytic uptake of fluorescently labeled latex beads and apoptotic cardiomyocyte H9c2 cells. We found that GAL conjugate enhanced the phagocytic activity of macrophage RAW264.7 cells in a concentration-dependent manner. Further mechanistic studies revealed that the effect of GAL conjugate on macrophage phagocytosis was positively correlated with the up-regulation of leukotriene B4 12-hydroxydehydrogenase (LTB4DH) expression at both mRNA and protein levels. By ESI-MS based lipidomics profiling, GAL conjugate increased the enzymatic activities of LTB4DH, leading to the formation of lipid metabolites including 12-oxo-LTB4, 13,14-dh-oxo-PGE2 and 13,14-dh-oxo-PGF2α. Interestingly, GAL conjugate failed to increase macrophage phagocytosis upon silencing of LTB4DH by specific siRNA. Moreover, it appeared that GAL conjugate induced LTB4DH expression via activating the Nrf2/HO-1 pathway. After Nrf-2 was silenced by specific siRNA, GAL conjugate no longer induced LTB4DH expression in the Nrf2-siRNA transfected cells. Taken together, our results suggest that GAL enhances macrophage phagocytosis via sequentially activating Nrf2 and up-regulating LTB4DH expression. Thus, GAL conjugate may serve as a lead compound for the development of new anti-inflammatory drugs. PMID:27148819

  8. Transport of L-leucine hydroxy analogue and L-lactate in rabbit small-intestinal brush-border membrane vesicles.

    PubMed

    Friedrich, M; Murer, H; Berger, E G

    1991-05-01

    Substitution of the alpha-amino group of amino acids by hydroxyl groups yields hydroxy analogues (HA), which have been ascribed beneficial effects in nitrogen-sparing diets for uremic patients. In this study, intestinal uptake of L-leucine HA (L-LeuHA) and L-lactate into rabbit jejunal brush-border membrane vesicles was investigated. An inward-directed H+ or Na+ gradient stimulated uptake of both labelled substrates in a voltage-clamped assay. The H+ gradient was the major driving force of uptake as compared with the Na+ gradient, and it led to a transient accumulation of both L-LeuHA and L-lactate. The proton ionophore carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP) reduced the initial H(+)-gradient-driven uptake rates of both substrates, but was without effect on Na(+)-gradient-driven uptakes. The H(+)-gradient-driven L-LeuHA uptake was saturable (apparent Kt = 15.4 mM). Alpha-HA of L-leucine, L-isoleucine, L-valine, D-leucine, D-valine or L-lactate inhibited the H(+)-gradient-driven L-LeuHA or L-lactate uptakes whereas free branched-chain amino acids had no effect. Preloading the vesicles with one of the L- or D-HA of branched-chain amino acids or with L-lactate stimulated tracer L-LeuHA and also tracer L-lactate uptakes in the presence of a H+ gradient. It is concluded that H(+)-gradient-driven transport of L- and D-stereoisomeric HA of branched-chain amino acids as well as of L-lactate across rabbit intestinal brush-border membranes is mediated by the same carrier. Furthermore, there exists a Na+ gradient-driven L-lactate transport system in the rabbit intestinal brush-border membrane. PMID:1876483

  9. Genetic analysis of pathway regulation for enhancing branched-chain amino acid biosynthesis in plants.

    PubMed

    Chen, Hao; Saksa, Kristen; Zhao, Feiyi; Qiu, Joyce; Xiong, Liming

    2010-08-01

    The branched-chain amino acids (BCAAs) valine, leucine and isoleucine are essential amino acids that play critical roles in animal growth and development. Animals cannot synthesize these amino acids and must obtain them from their diet. Plants are the ultimate source of these essential nutrients, and they synthesize BCAAs through a conserved pathway that is inhibited by its end products. This feedback inhibition has prevented scientists from engineering plants that accumulate high levels of BCAAs by simply over-expressing the respective biosynthetic genes. To identify components critical for this feedback regulation, we performed a genetic screen for Arabidopsis mutants that exhibit enhanced resistance to BCAAs. Multiple dominant allelic mutations in the VALINE-TOLERANT 1 (VAT1) gene were identified that conferred plant resistance to valine inhibition. Map-based cloning revealed that VAT1 encodes a regulatory subunit of acetohydroxy acid synthase (AHAS), the first committed enzyme in the BCAA biosynthesis pathway. The VAT1 gene is highly expressed in young, rapidly growing tissues. When reconstituted with the catalytic subunit in vitro, the vat1 mutant-containing AHAS holoenzyme exhibits increased resistance to valine. Importantly, transgenic plants expressing the mutated vat1 gene exhibit valine tolerance and accumulate higher levels of BCAAs. Our studies not only uncovered regulatory characteristics of plant AHAS, but also identified a method to enhance BCAA accumulation in crop plants that will significantly enhance the nutritional value of food and feed. PMID:20497381

  10. Derepression of Synthesis of the Aminoacyl-Transfer Ribonucleic Acid Synthetases for the Branched-Chain Amino Acids of Escherichia coli

    PubMed Central

    McGinnis, Etheleen; Williams, Ann C.; Williams, L. S.

    1974-01-01

    The kinetics of derepression of valyl-, isoleucyl-, and leucyl-transfer ribonucleic acid (tRNA) synthetase formation was examined during valine-, isoleucine-, and leucine-limited growth. When valine was limiting growth, valyl-tRNA synthetase formation was maximally derepressed within 5 min, whereas the rates of synthesis of isoleucyl-, and leucyl-tRNA synthetases were unchanged. Isoleucine-restricted growth caused a maximal derepression of isoleucyl-tRNA synthetase formation in 5 min and derepression of valyl-tRNA synthetase formation in 15 min with no effect on leucyl-tRNA synthetase formation. When leucine was limiting growth, leucyl-tRNA synthetase formation was immediately derepressed, whereas valyl- and isoleucyl-tRNA synthetase formation was unaffected by manipulation of the leucine supply to the cells. These results support our previous findings that valyl-tRNA synthetase formation is subject to multivalent repression control by both isoleucine and valine. In contrast, repression control of iso-leucyl- and leucyl-tRNA synthetase formation is specifically mediated by the supply of the cognate amino acid. PMID:4604302

  11. A novel D-leucine-containing Conus peptide: diverse conformational dynamics in the contryphan family.

    PubMed

    Jacobsen, R B; Jimenez, E C; De la Cruz, R G; Gray, W R; Cruz, L J; Olivera, B M

    1999-08-01

    A Conus peptide family (the contryphans) is noteworthy because of the presence of a post-translationally modified D-amino acid in all members of the family. A new contryphan peptide, Leu-contryphan-P, was isolated from the venom of Conus purpurascens; the sequence of this peptide is: Gly-Cys-Val-D-Leu-Leu-Pro-Trp-Cys-OH. This is the first known occurrence of D-leucine in a Conus peptide. The discovery of Leu-contryphan-P suggests that there may be branches of the contryphan peptide family that diverge much more in sequence than previously anticipated. Several natural contryphans provide dramatic examples of interconversion between multiple conformational states in small constrained peptides. The contryphans that have 4-trans-hydroxyproline and D-tryptophan in positions 3 and 4, respectively, exhibit two peaks under reverse-phase HPLC conditions, indicating interconversion between two discrete conformations. However, [L-Trp4]contryphan-Sm (with L-Trp substituted for D-Trp) exhibits a single, broad peak that elutes later than the natural peptide, suggesting that D-Trp stabilizes a conformation in which hydrophobic residues are buried. Leucontryphan-P which has valine and D-leucine instead of 4-trans-hydroxyproline and D-tryptophan shows only a single peak that elutes much later than the other contryphans. PMID:10461743

  12. Regulation of valine and. alpha. -ketoisocaproate metabolism in rat kidney mitochondria

    SciTech Connect

    Miller, R.H.; Harper, A.E. )

    1988-10-01

    Activities of branched-chain amino acid (BCAA) aminotransferase (BCAT) and {alpha}-keto acid dehydrogenase (BCKD) were assayed in mitochondria isolated from kidneys of rats. Rates of transamination of valine and oxidation of keto acids {alpha}-ketoisocaproate (KIC) or {alpha}-ketoisovalerate (KIV) were estimated using radioactive tracers of the appropriate substrate from amounts of {sup 14}C-labeled products formed. Because of the high mitochondrial BCAT activity, an amino acceptor for BCAT, {alpha}-ketoglutarate ({alpha}-KG) or KIC, was added to the assay medium when valine was the substrate. Rates of valine transamination and subsequent oxidation of the KIV formed were determined with 0.5 mM {alpha}-KG as the amino acceptor; these rates were 5- to 50-fold those without added {alpha}-KG. Rates of CO{sub 2} evolution from valine also increased when KIC was present; however, with KIC concentrations above 0.2 mM, rates of CO{sub 2} evolution from valine declined although rates of transamination continued to rise. When 0.05 mM KIC was added to the assay medium, oxidation of KIC was suppressed by inclusion of valine or glutamate in the medium. When valine was present KIC was not oxidized preferentially, presumably because it was also serving as an amino acceptor for BCAT. These results indicate that as the supply of amino acceptor, {alpha}-KG or KIC, is increased in mitochondria not only is the rate of valine transamination stimulated but also the rate of oxidation of the KIV formed from valine. Thus the rate of oxidation of BCAA can be controlled by factors that influence the rate and direction of BCAA transamination and, thereby, the supply of substrate for BCKD.

  13. Metabolic fate of the carboxyl-carbon of valine

    SciTech Connect

    Lathrop, K.A.; Bartlett, R.D.; Faulhaber, P.F.; Harper, P.V.

    1984-01-01

    Although several C-11-carboxyl-labeled amino acids show promise for clinical use, few detailed biokinetic studies have been reported. Such information is necessary for the calculation of comprehensive radiation absorbed doses and may reveal additional clinical uses. The authors have collected data in mice at intervals between 1 and 90 m after i.v. injection of D,L-, L-, or D-valine for 22 whole organs or tissue samples and for CO/sub 2/ and urinary excretion. The enantiomers were cleanly separated by HPLC, but studies with the D,L- mixture were also done as additional assurance of purity for the separation (i.e., (D+L)/2=D,L). Elimination of C-11 from L-valine is restricted to the approx. =25% of injected activity (IA) observed as exhaled CO/sub 2/, the production of which appears completed in approx. =15 m, the exhalation in approx. =100m. The remaining 75% IA is available for incorporation directly into proteins or into coenzyme-A after deamination to 2-oxoisovalerate. The approx. =25% IA from D-valine that appears to be retained in the body probably is not converted to L-valine since virtually no CO/sub 2/ is recovered. The pancreatic content of approx. =8% of retained activity (RA) for both L- and D- valine at 90 m suggests similar localization mechanisms for the activity remaining in the body after excretion is ended. A similar correspondence of RA is seen in most other organs, the notable exceptions being the approx. =2 to 3 times higher %RA in blood and muscle for D-valine and in small intestine for L-valine. Studies such as this offer the possibility for quantitation of isolated metabolic processes, in this case production of CO/sub 2/ from 2-oxoisovalerate formed by deamination, and for separating metabolized from non-metabolized localization of C-11 when the D-amino acid can be shown to remain undegraded.

  14. Estimation of the standardized ileal digestible valine to lysine ratio required for 25- to 120-kilogram pigs fed low crude protein diets supplemented with crystalline amino acids.

    PubMed

    Liu, X T; Ma, W F; Zeng, X F; Xie, C Y; Thacker, P A; Htoo, J K; Qiao, S Y

    2015-10-01

    Four 28-d experiments were conducted to determine the standardized ileal digestible (SID) valine (Val) to lysine (Lys) ratio required for 26- to 46- (Exp. 1), 49- to 70- (Exp. 2), 71- to 92- (Exp. 3), and 94- to 119-kg (Exp. 4) pigs fed low CP diets supplemented with crystalline AA. The first 3 experiments utilized 150 pigs (Duroc × Landrace × Large White), while Exp. 4 utilized 90 finishing pigs. Pigs in all 4 experiments were randomly allocated to 1 of 5 diets with 6 pens per treatment (3 pens of barrows and 3 pens of gilts) and 5 pigs per pen for the first 3 experiments and 3 pigs per pen for Exp. 4. Diets for all experiments were formulated to contain SID Val to Lys ratios of 0.55, 0.60, 0.65, 0.70, or 0.75. In Exp. 1 (26 to 46 kg), ADG increased (linear, = 0.039; quadratic, = 0.042) with an increasing dietary Val:Lys ratio. The SID Val:Lys ratio to maximize ADG was 0.62 using a linear broken-line model and 0.71 using a quadratic model. In Exp. 2 (49 to 70 kg), ADG increased (linear, = 0.021; quadratic, = 0.042) as the SID Val:Lys ratio increased. G:F improved (linear, = 0.039) and serum urea nitrogen (SUN) decreased (linear, = 0.021; quadratic, = 0.024) with an increased SID Val:Lys ratio. The SID Val:Lys ratios to maximize ADG as well as to minimize SUN levels were 0.67 and 0.65, respectively, using a linear broken-line model and 0.72 and 0.71, respectively, using a quadratic model. In Exp. 3 (71 to 92 kg), ADG increased (linear, = 0.007; quadratic, = 0.022) and SUN decreased (linear, = 0.011; quadratic, = 0.034) as the dietary SID Val:Lys ratio increased. The SID Val:Lys ratios to maximize ADG as well as to minimize SUN levels were 0.67 and 0.67, respectively, using a linear broken-line model and 0.72 and 0.74, respectively, using a quadratic model. In Exp. 4 (94 to 119 kg), ADG increased (linear, = 0.041) and G:F was improved (linear, = 0.004; quadratic, = 0.005) as the dietary SID Val:Lys ratio increased. The SID Val:Lys ratio to maximize G:F was 0

  15. Branched-chain amino acids are associated with cardiometabolic risk profiles found already in lean, overweight and obese young.

    PubMed

    Mangge, Harald; Zelzer, Sieglinde; Prüller, Florian; Schnedl, Wolfgang J; Weghuber, Daniel; Enko, Dietmar; Bergsten, Peter; Haybaeck, Johannes; Meinitzer, Andreas

    2016-06-01

    Cardiovascular risk is increased in obese subjects. Nevertheless, some overweight and obese remain cardiometabolically healthy (CMH), and normal-weight persons develop cardiovascular disease (CVD). Herein, we investigate the potential of branched-chain amino acids (BCAAs) to identify an increased CVD risk in a cross-sectional study of 666 adults and juveniles (age 25.3±12.8years), classified as lean, overweight or obese. Cardiometabolic groups were defined by cutoffs of systolic blood pressure<130mmHg, diastolic blood pressure<85mmHg, glucose<125mg/dl, triglycerides<150mg/dl, HDL-cholesterol>40mg/dl (males), HDL-cholesterol>50mg/dl (females) and HOMA-IR<5. CMH had ≤1 cutoff, and cardiometabolically abnormal (CMA) had ≥2 cutoffs. Amino acids were measured by high-pressure lipid chromatography after precipitation of serum with perchloric acid and derivatization with o-phthalaldehyde. Valine correlated with 5, leucine correlated with 3 and isoleucine correlated with 5 of the cardiac risk classification factors. Valine and leucine were significantly higher in the obese (P<.001, P=.015, respectively), overweight (P<.001, P=.015, respectively) and lean (P=.024, P=.012, respectively) CMA compared to CMH subjects. Isoleucine showed except of the lean group the same results. Taken together, BCAAs, especially valine and leucine, are proposed as a cardiometabolic risk marker independent of body mass index (BMI) category. PMID:27142745

  16. Amino acid availability and age affect the leucine stimulation of protein synthesis and eIF4F formation in muscle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have previously shown that a physiological increase in plasma leucine for 60 and 120 min increases translation initiation factor activation in muscle of neonatal pigs. Although muscle protein synthesis is increased by leucine at 60 min, it is not maintained at 120 min, perhaps because of the decr...

  17. Determination of 13C isotopic enrichment of valine and threonine by GC-C-IRMS after formation of the N(O,S)-ethoxycarbonyl ethyl ester derivatives of the amino acids.

    PubMed

    Godin, Jean-Philippe; Faure, Magali; Breuille, Denis; Hopfgartner, Gérard; Fay, Laurent-Bernard

    2007-06-01

    We describe a new method of assessing, in a single run, (13)C isotopic enrichment of both Val and Thr by gas chromatography-combustion-isotope-ratio mass spectrometry (GC-C-IRMS). This method characterised by a rapid one-step derivatisation procedure performed at room temperature to form the N(O,S)-ethoxycarbonyl ethyl ester derivatives, and a polar column for GC. The suitability of this method for Val and Thr in in-vivo samples (mucosal hydrolysate) was demonstrated by studying protein metabolism with two tracers ((13)C-valine or (13)C-threonine). The intra-day and inter-day repeatability were both assessed either with standards or with in-vivo samples at natural abundance and at low (13)C isotopic enrichment. For inter-day repeatability CVs were between 0.8 and 1.5% at natural abundance and lower than 5.5% at 0.112 and 0.190 atom% enrichment for Val and Thr, respectively. Overall isotopic precision was studied for eleven standard amino acid derivatives (those of Val, Ala, Leu, Iso, Gly, Pro, Asp, Thr, Ser, Met, and Phe) and was assessed at 0.32 per thousand. The (13)C isotopic measurement was then extended to the other amino acids (Ala, Val, Leu, Iso, Gly, Pro, Thr, and Phe) at natural abundance for in-vivo samples. The isotopic precision was better than 0.002 atom% per amino acid (for n = 4 rats). This analytical method was finally applied to an animal study to measure Thr utilization in protein synthesis. PMID:17468859

  18. Analytical continuation in coupling constant method; application to the calculation of resonance energies and widths for organic molecules: Glycine, alanine and valine and dimer of formic acid

    NASA Astrophysics Data System (ADS)

    Papp, P.; Matejčík, Š.; Mach, P.; Urban, J.; Paidarová, I.; Horáček, J.

    2013-06-01

    The method of analytic continuation in the coupling constant (ACCC) in combination with use of the statistical Padé approximation is applied to the determination of resonance energy and width of some amino acids and formic acid dimer. Standard quantum chemistry codes provide accurate data which can be used for analytic continuation in the coupling constant to obtain the resonance energy and width of organic molecules with a good accuracy. The obtained results are compared with the existing experimental ones.

  19. Desorption yield for valine as induced by fast heavy ions

    SciTech Connect

    Beining, P.; Scheer, J.; Nieschler, E.; Nees, B.; Voit, H.

    1988-11-01

    The dependence of the desorption yield for the amino acid valine on the energy of different MeV primary ions has been measured. The primary-ion energies cover a relatively large range with corresponding energy losses between 2 and 55 keV/(..mu..g/cm/sup 2/). The observed energy dependence can be understood in the framework of a simple macroscopic model.

  20. Partial molar volume of L-Valine in water under high pressure

    NASA Astrophysics Data System (ADS)

    Sawamura, Seiji

    2013-06-01

    Partial molar volume of L-valine in water was estimated up to 400 MPa from pressure coefficient of the solubility of the solute and molar volume of solid valine. The former was measured in a previous paper and the latter was measured in this article using a piston-cylinder typed cell. The partial molar volume increased with pressure and a maximum was observed around 250 MPa. It was compared with other amino acids.

  1. High-Speed Microdialysis-Capillary Electrophoresis Assays for Measuring Branched Chain Amino Acid Uptake in 3T3-L1 cells.

    PubMed

    Harstad, Rachel K; Bowser, Michael T

    2016-08-16

    We have developed a high-throughput microdialysis-capillary electrophoresis (MD-CE) assay for monitoring branched chain amino acid (BCAA) uptake/release dynamics in 3T3-L1 cells. BCAAs (i.e., isoleucine, leucine, and valine) and their downstream metabolites (i.e., alanine, glutamine, and glutamate) are important indicators of adipocyte lipogenesis. To perform an analysis, amino acids were sampled using microdialysis, fluorescently labeled in an online reaction, separated using CE, and detected using laser-induced fluorescence (LIF) in a sheath flow cuvette. Separation conditions were optimized for the resolution of the BCAAs isoleucine, leucine, and valine, as well as 13 other amino acids, including ornithine, alanine, glutamine, and glutamate. CE separations were performed in <30 s, and the temporal resolution of the online MD-CE assay was <60 s. Limits of detection (LOD) were 400, 200, and 100 nM for isoleucine, leucine, and valine, respectively. MD-CE dramatically improved throughput in comparison to traditional offline CE methods, allowing 8 replicates of 15 samples (i.e., 120 analyses) to be assayed in <120 min. The MD-CE assay was used to assess the metabolism dynamics of 3T3-L1 cells over time, confirming the utility of the assay. PMID:27398773

  2. Potent anti-seizure effects of D-leucine.

    PubMed

    Hartman, Adam L; Santos, Polan; O'Riordan, Kenneth J; Stafstrom, Carl E; Hardwick, J Marie

    2015-10-01

    There are no effective treatments for millions of patients with intractable epilepsy. High-fat ketogenic diets may provide significant clinical benefit but are challenging to implement. Low carbohydrate levels appear to be essential for the ketogenic diet to work, but the active ingredients in dietary interventions remain elusive, and a role for ketogenesis has been challenged. A potential antiseizure role of dietary protein or of individual amino acids in the ketogenic diet is understudied. We investigated the two exclusively ketogenic amino acids, L-leucine and L-lysine, and found that only L-leucine potently protects mice when administered prior to the onset of seizures induced by kainic acid injection, but not by inducing ketosis. Unexpectedly, the D-enantiomer of leucine, which is found in trace amounts in the brain, worked as well or better than L-leucine against both kainic acid and 6Hz electroshock-induced seizures. However, unlike L-leucine, D-leucine potently terminated seizures even after the onset of seizure activity. Furthermore, D-leucine, but not L-leucine, reduced long-term potentiation but had no effect on basal synaptic transmission in vitro. In a screen of candidate neuronal receptors, D-leucine failed to compete for binding by cognate ligands, potentially suggesting a novel target. Even at low doses, D-leucine suppressed ongoing seizures at least as effectively as diazepam but without sedative effects. These studies raise the possibility that D-leucine may represent a new class of anti-seizure agents, and that D-leucine may have a previously unknown function in eukaryotes. PMID:26054437

  3. Comparison of leucine and dispensable amino acid kinetics between Indian women with low or normal body mass indexes during pregnancy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evidence suggests that in women with a normal to high body mass index (BMI; in kg/m(2)), the extra amino acids needed during pregnancy are met through reduced oxidation. It is not known whether a woman with a low BMI can make this adaptation successfully. The objective was to measure and compare leu...

  4. Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) association with lymph node metastasis predicts poor survival in oral squamous cell carcinoma patients

    PubMed Central

    Lee, Chien-Hung; Lin, Shu-Hui; Chin, Mei-Chung; Chiang, Shang-Lun; Wang, Zhi-Hong; Hua, Chun-Hung; Tsai, Ming-Hsui; Chang, Jan-Gowth; Ko, Ying-Chin

    2016-01-01

    Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) is a multifunctional protein aberrantly expressed in various types of cancers. However, its expression pattern and clinical significance in oral squamous cell carcinoma (OSCC) remains unclear. In this study, we immunohistochemically investigated the expression pattern of ANP32A in 259 OSCC patients and the results were correlated with clinicopathological factors using Allred, Klein and Immunoreactive scoring (IRS) system. Our data indicated that high expression of ANP32A was significantly associated with N stage and tumor differentiation status in OSCC patients. High ANP32A expression with N2/N3 stage had an increased mortality risk than low ANP32A expressing OSCC patients with N0/N1 stage. Functional studies revealed that knockdown of ANP32A significantly decreased the migration and invasion ability thereby concomitantly increasing E-cadherin and decreasing Slug, Claudin-1 and Vimentin expression in vitro. These results suggest that ANP32A is commonly increased in oral squamous cell carcinoma and ANP32A protein could act as a potential biomarker for prognosis assessment of oral cancer patients with lymph node metastasis. PMID:26918356

  5. L: -Stereoselective amino acid amidase with broad substrate specificity from Brevundimonas diminuta: characterization of a new member of the leucine aminopeptidase family.

    PubMed

    Komeda, Hidenobu; Hariyama, Nozomi; Asano, Yasuhisa

    2006-04-01

    Brevundimonas diminuta TPU 5720 produces an amidase acting L-stereoselectively on phenylalaninamide. The enzyme (LaaA(Bd)) was purified to electrophoretic homogeneity by ammonium sulfate fractionation and four steps of column chromatography. The final preparation gave a single band on SDS-PAGE with a molecular weight of approximately 53,000. The native molecular weight of the enzyme was about 288,000 based on gel filtration chromatography, suggesting that the enzyme is active as a homohexamer. It had maximal activity at 50 degrees C and pH 7.5. LaaA(Bd) lost its activity almost completely on dialysis against potassium phosphate buffer (pH 7.0), and the amidase activity was largely restored by the addition of Co(2+) ions. The enzyme was, however, inactivated in the presence of ethylenediaminetetraacetic acid even in the presence of Co(2+), suggesting that LaaA(Bd) is a Co(2+)-dependent enzyme. LaaA(Bd) had hydrolyzing activity toward a broad range of L-amino acid amides including L-phenylalaninamide, L-glutaminamide, L-leucinamide, L-methioninamide, L-argininamide, and L-2-aminobutyric acid amide. Using information on the N-terminal amino acid sequence of the enzyme, the gene encoding LaaA(Bd) was cloned from the chromosomal DNA of the strain and sequenced. Analysis of 4,446 bp of the cloned DNA revealed the presence of seven open-reading frames (ORFs), one of which (laaA ( Bd )) encodes the amidase. LaaA(Bd) is composed of 491 amino acid residues (calculated molecular weight 51,127), and the deduced amino acid sequence exhibits significant similarity to that of ORFs encoding hypothetical cytosol aminopeptidases found in the genomes of Caulobacter crescentus, Bradyrhizobium japonicum, Rhodopseudomonas palustris, Mesorhizobium loti, and Agrobacterium tumefaciens, and leucine aminopeptidases, PepA, from Rickettsia prowazekii, Pseudomonas putida ATCC 12633, and Escherichia coli K-12. The laaA ( Bd ) gene modified in the nucleotide sequence upstream from its start codon

  6. Gene expression, serum amino acid levels, and growth performance of pigs fed dietary leucine and lysine at different ratios.

    PubMed

    García, H; Morales, A; Araiza, A; Htoo, J K; Cervantes, M

    2015-01-01

    We examined 96 pigs (28.1 ± 0.83 kg) to analyze the effect of Leu:Lys ratios on expression of the cationic amino acid transporters b(0,+) and CAT-1 in the jejunum and liver as well as myosin expression in 2 muscles to estimate the optimum standardized ileal digestible (SID) Leu:Lys ratio for growth rate and efficiency. A wheat-and wheat bran-based diets were formulated to meet the requirements of SID amino acids other than Leu (0.70%) and Lys (0.80%). L-Leu was added to the basal diet in 5 SID Leu:Lys ratios (88, 100, 120, 140, and 160% in diets 1-5). Tissue samples were collected from 8 pigs with ratios of 88, 120, and 160%. Relative expression of b(0,+), CAT-1, and myosin was analyzed. b(0,+) expression in the jejunum was higher but lower in the liver of pigs with the 120% ratio compared to those with the 88 or 160% ratio; myosin expression in longissimus dorsi was also higher in pigs with the 120% ratio (P < 0.05). CAT-1 was lower in the jejunum and longissimus dorsi of pigs with 120 or 160% ratios than in pigs with 88%. Serum concentration of nearly all amino acids decreased with excess dietary Leu (P < 0.05). The SID Leu:Lys of 104 and 109% optimized average daily gain and feed conversion ratio, respectively. Thus, the dietary Leu:Lys ratio affects the expression of genes coding for amino acid transporters and myosin, the availability of Lys, and the growth rate and efficiency in pigs. PMID:25867302

  7. Compartmental model of leucine kinetics in humans.

    PubMed

    Cobelli, C; Saccomani, M P; Tessari, P; Biolo, G; Luzi, L; Matthews, D E

    1991-10-01

    The complexity of amino acid and protein metabolism has limited the development of comprehensive, accurate whole body kinetic models. For leucine, simplified approaches are in use to measure in vivo leucine fluxes, but their domain of validity is uncertain. We propose here a comprehensive compartmental model of the kinetics of leucine and alpha-ketoisocaproate (KIC) in humans. Data from a multiple-tracer administration were generated with a two-stage (I and II) experiment. Six normal subjects were studied. In experiment I, labeled leucine and KIC were simultaneously injected into plasma. Four plasma leucine and KIC tracer concentration curves and label in the expired CO2 were measured. In experiment II, labeled bicarbonate was injected into plasma, and labeled CO2 in the expired air was measured. Radioactive (L-[1-14C]leucine, [4,5-3H]KIC, [14C]bicarbonate) and stable isotope (L-[1-13C]leucine, [5,5,5-2H3]KIC, [13C]bicarbonate) tracers were employed. The input format was a bolus (impulse) dose in the radioactive case and a constant infusion in the stable isotope case. A number of physiologically based, linear time-invariant compartmental models were proposed and tested against the data. The model finally chosen for leucine-KIC kinetics has 10 compartments: 4 for leucine, 3 for KIC, and 3 for bicarbonate. The model is a priori uniquely identifiable, and its parameters were estimated with precision from the five curves of experiment I. The separate assessment of bicarbonate kinetics (experiment II) was shown to be unnecessary. The model defines masses and fluxes of leucine in the organism, in particular its intracellular appearance from protein breakdown, its oxidation, and its incorporation into proteins. An important feature of the model is its ability to estimate leucine oxidation by resolving the bicarbonate model in each individual subject. Finally, the model allows the assessment of the domain of validity of the simpler commonly used models. PMID:1928344

  8. Synthesis of poly(alkenoic acid) with L-leucine residue and methacrylate photopolymerizable groups useful in formulating dental restorative materials.

    PubMed

    Buruiana, Tinca; Nechifor, Marioara; Melinte, Violeta; Podasca, Viorica; Buruiana, Emil C

    2014-01-01

    To develop resin-modified glass ionomer materials, we synthesized methacrylate-functionalized acrylic copolymer (PAlk-LeuM) derived from acrylic acid, itaconic acid and N-acryloyl-L-leucine using (N-methacryloyloxyethylcarbamoyl-N'-4-hydroxybutyl) urea as the modifying agent. The spectroscopic (proton/carbon nuclear magnetic resonance, Fourier transform infrared spectroscopy) characteristics, and the gel permeation chromatography/Brookfield viscosity measurements were analysed and compared with those of the non-modified copolymer (PAlk-Leu). The photocurable copolymer (PAlk-LeuM, ~14 mol% methacrylate groups) and its precursor (PAlk-Leu) were incorporated in dental ionomer compositions besides diglycidyl methacrylate of bisphenol A (Bis-GMA) or an analogue of Bis-GMA (Bis-GMA-1), triethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate. The kinetic data obtained by photo-differential scanning calorimetry showed that both the degree of conversion (60.50-75.62%) and the polymerization rate (0.07-0.14 s(-1)) depend mainly on the amount of copolymer (40-50 wt.%), and conversions over 70% were attained in the formulations with 40 wt.% PAlk-LeuM. To formulate light-curable cements, each organic composition was mixed with filler (90 wt.% fluoroaluminosilicate/10 wt.% hydroxyapatite) into a 2.7:1 ratio (powder/liquid ratio). The light-cured specimens exhibited flexural strength (FS), compressive strength (CS) and diametral tensile strength (DTS) varying between 28.08 and 64.79 MPa (FS), 103.68-147.13 MPa (CS) and 16.89-31.87 MPa (DTS). The best values for FS, CS and DTS were found for the materials with the lowest amount of PAlk-LeuM. Other properties such as the surface hardness, water sorption/water solubility, surface morphology and fluorescence caused by adding the fluorescein monomer were also evaluated. PMID:24701975

  9. Drug permeation and cellular interaction of amino acid-coated drug combination powders for pulmonary delivery.

    PubMed

    Vartiainen, Ville; Bimbo, Luis M; Hirvonen, Jouni; Kauppinen, Esko I; Raula, Janne

    2016-05-17

    The effect of three amino acid coatings (L-leucine, L-valine and L-phenylalanine) on particle integrity, aerosolization properties, cellular interaction, cytocompatibility, and drug permeation properties of drug combination powder particles (beclomethasone dipropionate and salbutamol sulphate) for dry powder inhalation (DPI) was investigated. Particles with crystalline L-leucine coating resulted in intact separated particles, with crystalline L-valine coating in slightly sintered particles and with amorphous L-phenylalanine coating in strongly fused particles. The permeation of beclomethasone dipropionate across a Calu-3 differentiated cell monolayer was increased when compared with its physical mixture. Drug crystal formation was also observed on the Calu-3 cell monolayer. The L-leucine coated particles were further investigated for cytocompatibility in three human pulmonary (Calu-3, A549 and BEAS-2B) and one human macrophage (THP-1) cell lines, where they showed excellent tolerability. The l-leucine coated particles were also examined for their ability to elicit reactive oxygen species in pulmonary BEAS-2B and macrophage THP-1 cell lines. The study showed the influence of the amino acid coatings for particle formation and performance and their feasibility for combination therapy for pulmonary delivery. PMID:27034001

  10. Directed evolution of leucine dehydrogenase for improved efficiency of L-tert-leucine synthesis.

    PubMed

    Zhu, Lin; Wu, Zhe; Jin, Jian-Ming; Tang, Shuang-Yan

    2016-07-01

    L-tert-Leucine and its derivatives are used as synthetic building blocks for pharmaceutical active ingredients, chiral auxiliaries, and ligands. Leucine dehydrogenase (LeuDH) is frequently used to prepare L-tert-leucine from the α-keto acid precursor trimethylpyruvate (TMP). In this study, a high-throughput screening method for the L-tert-leucine synthesis reaction based on a spectrophotometric approach was developed. Directed evolution strategy was applied to engineer LeuDH from Lysinibacillus sphaericus for improved efficiency of L-tert-leucine synthesis. After two rounds of random mutagenesis, the specific activity of LeuDH on the substrate TMP was enhanced by more than two-fold, compared with that of the wild-type enzyme, while the activity towards its natural substrate, leucine, decreased. The catalytic efficiencies (k cat/K m) of the best mutant enzyme, H6, on substrates TMP and NADH were all enhanced by more than five-fold as compared with that of the wild-type enzyme. The efficiency of L-tert-leucine synthesis by mutant H6 was significantly improved. A productivity of 1170 g/l/day was achieved for the mutant enzyme H6, compared with 666 g/l/day for the wild-type enzyme. PMID:26898942

  11. Pathway for isoleucine formation form pyruvate by leucine biosynthetic enzymes in leucine-accumulating isoleucine revertants of Serratia marcescens.

    PubMed

    Kisumi, M; Komatsubara, S; Chibata, I

    1977-07-01

    Leaky revertants isolated from isoleucine auxotrophs of Serratia marcescens mutant resistant to alpha-aminobutyric acid were previously reported to accumulate leucine in the medium, due to the absence of both feedback inhibition and repression of leucine biosynthesis. Growth of the revertant was accelerated by pyruvate, D(-)-citramalate, citraconate, and alpha-ketobutyrate, but not by threonine. Extracts of the revertant exhibited high activities of pyruvate-dependent coenzyme A liberation from acetyl-coenzyme A, hydration of citraconate, and conversion of citraconate to alpha-ketobutyrate, but showed no threonine-deaminating activity. In the leucine-accumulating revertants the above three activities were not affected by leucine, but in the wild strain and other revertants accumulating no leucine all or one of these activities was controlled by leucine. A leucine auxotroph isolated from the leucine-accumulating revertant showed isoleucine auxotrophy as well. From these data, it is concluded that, in leucine-accumulating revertants, of S. marcescent, isoleucine, is synthesized from alpha-ketobutyrate via citramalate formed from pyruvate annd acetyl-coenzyme A by leucine biosynthetic enzymes, as a result of desensitization of alpha-isopropylmalate synthetase to feedback inhibition. PMID:142769

  12. Conditions for the formation of dilysyl-dipyrrolones A and B, and novel yellow dipyrrolone derivatives formed from xylose and amino acids in the presence of lysine.

    PubMed

    Nomi, Yuri; Sakamoto, Junko; Takenaka, Makiko; Ono, Hiroshi; Murata, Masatsune

    2011-01-01

    Foods derived from plants contain pentose in addition to hexose. It is well known that pentose contributes more to browning by the Maillard reaction than hexose does. We have recently found novel yellow compounds formed from xylose and lysine under weakly acidic conditions, named dilysyldipyrrolones (dilysyl-DPLs) A and B. We indicate in this study that dilysyl-DPLs were specifically formed under weakly acidic conditions from pentose, but not hexose. Moreover, we found novel DPL derivatives which were formed from xylose and such amino acids as alanine, arginine, aspartic acid, glutamic acid, isoleucine, leucine, phenylalanine, serine, and valine in the presence of lysine. PMID:21307606

  13. Efficient synthesis of D-branched-chain amino acids and their labeled compounds with stable isotopes using D-amino acid dehydrogenase.

    PubMed

    Akita, Hironaga; Suzuki, Hirokazu; Doi, Katsumi; Ohshima, Toshihisa

    2014-02-01

    D-Branched-chain amino acids (D-BCAAs) such as D-leucine, D-isoleucine, and D-valine are known to be peptide antibiotic intermediates and to exhibit a variety of bioactivities. Consequently, much effort is going into achieving simple stereospecific synthesis of D-BCAAs, especially analogs labeled with stable isotopes. Up to now, however, no effective method has been reported. Here, we report the establishment of an efficient system for enantioselective synthesis of D-BCAAs and production of D-BCAAs labeled with stable isotopes. This system is based on two thermostable enzymes: D-amino acid dehydrogenase, catalyzing NADPH-dependent enantioselective amination of 2-oxo acids to produce the corresponding D-amino acids, and glucose dehydrogenase, catalyzing NADPH regeneration from NADP(+) and D-glucose. After incubation with the enzymes for 2 h at 65°C and pH 10.5, 2-oxo-4-methylvaleric acid was converted to D-leucine with an excellent yield (>99 %) and optical purity (>99 %). Using this system, we produced five different D-BCAAs labeled with stable isotopes: D-[1-(13)C,(15)N]leucine, D-[1-(13)C]leucine, D-[(15)N]leucine, D-[(15)N]isoleucine, and D-[(15)N]valine. The structure of each labeled D-amino acid was confirmed using time-of-flight mass spectrometry and nuclear magnetic resonance analysis. These analyses confirmed that the developed system was highly useful for production of D-BCAAs labeled with stable isotopes, making this the first reported enzymatic production of D-BCAAs labeled with stable isotopes. Our findings facilitate tracer studies investigating D-BCAAs and their derivatives. PMID:23661083

  14. Raman and surface-enhanced Raman spectroscopy of amino acids and nucleotide bases for target bacterial vibrational mode identification

    NASA Astrophysics Data System (ADS)

    Guicheteau, Jason; Argue, Leanne; Hyre, Aaron; Jacobson, Michele; Christesen, Steven D.

    2006-05-01

    Raman and surface-enhanced Raman spectroscopy (SERS) studies of bacteria have reported a wide range of vibrational mode assignments associated with biological material. We present Raman and SER spectra of the amino acids phenylalanine, tyrosine, tryptophan, glutamine, cysteine, alanine, proline, methionine, asparagine, threonine, valine, glycine, serine, leucine, isoleucine, aspartic acid and glutamic acid and the nucleic acid bases adenosine, guanosine, thymidine, and uridine to better characterize biological vibrational mode assignments for bacterial target identification. We also report spectra of the bacteria Bacillus globigii, Pantoea agglomerans, and Yersinia rhodei along with band assignments determined from the reference spectra obtained.

  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. Regulation of yeast acetohydroxyacid synthase by valine and ATP.

    PubMed Central

    Pang, S S; Duggleby, R G

    2001-01-01

    The first step in the common pathway for the biosynthesis of branched-chain amino acids is catalysed by acetohydroxyacid synthase (AHAS; EC 4.1.3.18). The enzyme is found in plants, fungi and bacteria, and is regulated by controls on transcription and translation, and by allosteric modulation of catalytic activity. It has long been known that the bacterial enzyme is composed of two types of subunit, and a similar arrangement has been found recently for the yeast and plant enzymes. One type of subunit contains the catalytic machinery, whereas the other has a regulatory function. Previously, we have shown [Pang and Duggleby (1999) Biochemistry 38, 5222--5231] that yeast AHAS can be reconstituted from its separately purified subunits. The reconstituted enzyme is inhibited by valine, and ATP reverses this inhibition. In the present work, we further characterize the structure and the regulatory properties of reconstituted yeast AHAS. High phosphate concentrations are required for reconstitution and it is shown that these conditions are necessary for physical association between the catalytic and regulatory subunits. It is demonstrated by CD spectral changes that ATP binds to the regulatory subunit alone, most probably as MgATP. Neither valine nor MgATP causes dissociation of the regulatory subunit from the catalytic subunit. The specificity of valine inhibition and MgATP activation are examined and it is found that the only effective analogue of either regulator of those tested is the non-hydrolysable ATP mimic, adenosine 5'-[beta,gamma-imido]triphosphate. The kinetics of regulation are studied in detail and it is shown that the activation by MgATP depends on the valine concentration in a complex manner that is consistent with a proposed quantitative model. PMID:11463345

  17. Amino Acid Metabolism of Lemna minor L. 1

    PubMed Central

    Rhodes, David; Hogan, Austin L.; Deal, Luanne; Jamieson, Gene C.; Haworth, Philip

    1987-01-01

    Chlorsulfuron, an inhibitor of acetolactate synthase (EC 4.1.3.18) (TB Ray 1984 Plant Physiol 75: 827-831), markedly inhibited the growth of Lemna minor at concentrations of 10−8 molar and above, but had no inhibitory effects on growth at 10−9 molar. At growth inhibitory concentrations, chlorsulfuron caused a pronounced increase in total free amino acid levels within 24 hours. Valine, leucine, and isoleucine, however, became smaller percentages of the total free amino acid pool as the concentration of chlorsulfuron was increased. At concentrations of chlorsulfuron of 10−8 molar and above, a new amino acid was accumulated in the free pool. This amino acid was identified as α-amino-n-butyrate by chemical ionization and electron impact gas chromatography-mass spectrometry. The amount of α-amino-n-butyrate increased from undetectable levels in untreated plants, to as high as 840 nanomoles per gram fresh weight (2.44% of the total free pool) in plants treated with 10−4 molar chlorsulfuron for 24 hours. The accumulation of this amino acid was completely inhibited by methionine sulfoximine. Chlorsulfuron did not inhibit the methionine sulfoximine induced accumulations of valine, leucine, and isoleucine, supporting the idea that the accumulation of the branched-chain amino acids in methionine sulfoximine treated plants is the result of protein turnover rather than enhanced synthesis. Protein turnover may be primarily responsible for the failure to achieve complete depletion of valine, leucine, and isoleucine even at concentrations of chlorsulfuron some 104 times greater than that required to inhibit growth. Tracer studies with 15N demonstrate that chlorsulfuron inhibits the incorporation of 15N into valine, leucine, and isoleucine. The α-amino-n-butyrate accumulated in the presence of chlorsulfuron and [15N]H4+ was heavily labeled with 15N at early time points and appeared to be derived by transamination from a rapidly labeled amino acid such as glutamate or

  18. Application of metabolic engineering for the biotechnological production of L-valine.

    PubMed

    Oldiges, Marco; Eikmanns, Bernhard J; Blombach, Bastian

    2014-07-01

    The branched chain amino acid L-valine is an essential nutrient for higher organisms, such as animals and humans. Besides the pharmaceutical application in parenteral nutrition and as synthon for the chemical synthesis of e.g. herbicides or anti-viral drugs, L-valine is now emerging into the feed market, and significant increase of sales and world production is expected. In accordance, well-known microbial production bacteria, such as Escherichia coli and Corynebacterium glutamicum strains, have recently been metabolically engineered for efficient L-valine production under aerobic or anaerobic conditions, and the respective cultivation and production conditions have been optimized. This review summarizes the state of the art in L-valine biosynthesis and its regulation in E. coli and C. glutamicum with respect to optimal metabolic network for microbial L-valine production, genetic strain engineering and bioprocess development for L-valine production, and finally, it will shed light on emerging technologies that have the potential to accelerate strain and bioprocess engineering in the near future. PMID:24816722

  19. Concomitant extracellular accumulation of alpha-keto acids and higher alcohols by Zygosaccharomyces rouxii.

    PubMed

    Van Der Sluis, Catrinus; Rahardjo, Yovita S P; Smit, Bart A; Kroon, Pieter J; Hartmans, Sybe; Ter Schure, Eelko G; Tramper, Johannes; Wijffels, Renéh

    2002-01-01

    Alpha-keto acids are key intermediates in the formation of higher alcohols, important flavor components in soy sauce, and produced by the salt-tolerant yeast Zygosaccharomyces rouxii. Unlike most of the higher alcohols, the alpha-keto acids are usually not extracellularly accumulated by Z. rouxii when it is cultivated with ammonium as the sole nitrogen source. To facilitate extracellular accumulation of the alpha-keto acids from aspartate-derived amino acid metabolism, the amino acids valine, leucine, threonine and methionine were exogenously supplied during batch and A-star cultivations of (routants of) Z. rouxii. It was shown that all alpha-keto acids from the aspartate-derived amino acid metabolism, except alpha-ketobutyrate, could be extracellularly accumulated. In addition, it appeared from the concomitant extracellular accumulation of alpha-keto acids and higher alcohols that in Z. rouxii, valine, leucine and methionine were converted via Ehrlich pathways similar to those in Saccharomyces cerevisiae. Unlike these amino acids, threonine was converted via both the Ehrlich and amino acid biosynthetic pathways in Z. rouxii. PMID:16233175

  20. In vitro and in vivo antitumor effects of novel actinomycin D analogs with amino acid substituted in the cyclic depsipeptides.

    PubMed

    Zhang, Bang-zhi; Wang, Kai-rong; Yan, Jie-xi; Zhang, Wei; Song, Jing-jing; Ni, Jing-man; Wang, Rui

    2010-04-01

    The actinomycin D (AMD) analogs in which the D-valine residues (the second amino acid residue in the cyclic depsipeptide of AMD) and the N-methyl-L-valine residues (the fifth amino acid residue in the cyclic depsipeptide of AMD) were replaced with D-Phe or l- and D-forms N-methylvalines, N-methylisoleucine, N-methylleucine, N-methylphenylalanine, N-methylalanine, and sarcosine were synthesized. The antimicrobial activity and cytotoxic activities of these compounds in vitro were investigated. The results showed that most D-valine substituted analogs had much lower antimicrobial activity and cytotoxic activities in vitro than AMD itself, but three N-methyl-L-valine substituted analogs had comparable or even more remarkable cytotoxic activities in vitro than AMD. Acute toxicities and antitumor effects of the N-methyl-L-valine substituted analogs in mice were also examined. The result showed that the acute toxicity of compound 4 L-methylleucine(5)-AMD analog is comparable to AMD itself and that of compound 3(L-Methylisoleucine(5)-AMD analog) is slightly more toxic, about 1.25-fold than AMD. However, the acute toxicity of compound 5 D-methylleucine5-AMD analog is about 2-fold lower than AMD. This suggested that the N-methyl-D-amino acid replacement in the cyclic ring might play a vital role in their decreased acute toxicities, and perhaps the N-methyl-D-leucine substituent is more favorable, though there may be a slight loss of antitumor activity. This finding may be helpful for the design and development of more potent antitumor agents together with low acute toxicity, and suggests that the N-methyl-D-leucine substituent has the potential to be used as antitumor drug lead. PMID:20045716

  1. Short-term and long-term ethanol administration inhibits the placental uptake and transport of valine in rats

    SciTech Connect

    Patwardhan, R.V.; Schenker, S.; Henderson, G.I.; Abou-Mourad, N.N.; Hoyumpa, A.M. Jr.

    1981-08-01

    Ethanol ingestion during pregnancy causes a pattern of fetal/neonatal dysfunction called the FAS. The effects of short- and long-term ethanol ingestion on the placental uptake and maternal-fetal transfer of valine were studied in rats. The in vivo placental uptake and fetal uptake were estimated after injection of 0.04 micromol of /sub 14/C-valine intravenously on day 20 of gestation in Sprague-Dawley rats. Short-term ethanol ingestion (4 gm/kg) caused a significant reduction in the placental uptake of /sub 14/C-valine by 33%, 60%, and 30%, and 31% at 2.5, 5, 10, and 15 min after valine administration, respectively (p less than 0.01), and a similar significant reduction occurred in the fetal uptake of /sub 14/C-valine (p less than 0.01). Long-term ethanol ingestion prior to and throughout gestation resulted in a 47% reduction in placental valine uptake (p less than 0.01) and a 46% reduction in fetal valine uptake (p less than 0.01). Long-term ethanol feeding from day 4 to day 20 of gestation caused a 32% reduction in placental valine uptake (p less than 0.01) and a 26% reduction in fetal valine uptake (p less than 0.01). We conclude that both short- and long-term ingestion of ethanol inhibit the placental uptake and maternal-fetal transfer of an essential amino acid--valine. An alteration of placental function may contribute to the pathogenesis of the FAS.

  2. Protein and leucine metabolism in maple syrup urine disease

    SciTech Connect

    Thompson, G.N.; Bresson, J.L.; Pacy, P.J.; Bonnefont, J.P.; Walter, J.H.; Leonard, J.V.; Saudubray, J.M.; Halliday, D. )

    1990-04-01

    Constant infusions of (13C)leucine and (2H5)phenylalanine were used to trace leucine and protein kinetics, respectively, in seven children with maple syrup urine disease (MSUD) and eleven controls matched for age and dietary protein intake. Despite significant elevations of plasma leucine (mean 351 mumol/l, range 224-477) in MSUD subjects, mean whole body protein synthesis (3.78 +/- 0.42 (SD) g.kg-1. 24 h-1) and catabolism (4.07 +/- 0.46) were similar to control values (3.69 +/- 0.50 and 4.09 +/- 0.50, respectively). The relationship between phenylalanine and leucine fluxes was also similar in MSUD subjects (mean phenylalanine-leucine flux ratio 0.35 +/- 0.07) and previously reported adult controls (0.33 +/- 0.02). Leucine oxidation was undetectable in four of the MSUD subjects and very low in the other three (less than 4 mumol.kg-1.h-1; controls 13-20). These results show that persistent elevation in leucine concentration has no effect on protein synthesis. The marked disturbance in leucine metabolism in MSUD did not alter the relationship between rates of catabolism of protein to phenylalanine and leucine, which provides further support for the validity of the use of a single amino acid to trace whole body protein metabolism. The minimal leucine oxidation in MSUD differs from findings in other inborn metabolic errors and indicates that in patients with classical MSUD there is no significant route of leucine disposal other than through protein synthesis.

  3. Leucine metabolism in human newborns

    SciTech Connect

    Denne, S.C.; Kalhan, S.C. )

    1987-12-01

    The present study was designed to (1) determine whether a relationship exists between newborn birth weight and leucine metabolism and (2) compare leucine and energy metabolism in a period of rapid growth and development (i.e., newborn) with a constant nongrowth period (i.e., adult). Leucine kinetics and energy expenditure were measured in the postabsorptive state in 12 normal full-term newborns in early neonatal life and in 11 normal adults using a primed constant L-(1-{sup 13}C)leucine infusion combined with respiratory calorimetry. A significant positive correlation between newborn birth weight and leucine flux was observed. These data suggest the following. (1) A relationship exists between newborn birth weight and protein metabolism, as reflected by the correlation between leucine flux when expressed as micromoles per kilogram per hour and birth weight. (2) The high rate of leucine flux measured in newborns probably reflects the rapid remodeling of protein that occurs in this period of development, even during fasting. (3) The similar values in newborns and adults of leucine kinetics and energy expenditure when normalized to metabolic body weight and the nearly equivalent allometric exponents relating body weight to leucine flux and energy expenditure support a close relationship between leucine and energy metabolism, at least at the extremes of human growth.

  4. The Basic Leucine Zipper Transcription Factor ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 Is an Important Transcriptional Regulator of Abscisic Acid-Dependent Grape Berry Ripening Processes1[W][OPEN

    PubMed Central

    Nicolas, Philippe; Lecourieux, David; Kappel, Christian; Cluzet, Stéphanie; Cramer, Grant; Delrot, Serge; Lecourieux, Fatma

    2014-01-01

    In grape (Vitis vinifera), abscisic acid (ABA) accumulates during fruit ripening and is thought to play a pivotal role in this process, but the molecular basis of this control is poorly understood. This work characterizes ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 (VvABF2), a grape basic leucine zipper transcription factor belonging to a phylogenetic subgroup previously shown to be involved in ABA and abiotic stress signaling in other plant species. VvABF2 transcripts mainly accumulated in the berry, from the onset of ripening to the harvesting stage, and were up-regulated by ABA. Microarray analysis of transgenic grape cells overexpressing VvABF2 showed that this transcription factor up-regulates and/or modifies existing networks related to ABA responses. In addition, grape cells overexpressing VvABF2 exhibited enhanced responses to ABA treatment compared with control cells. Among the VvABF2-mediated responses highlighted in this study, the synthesis of phenolic compounds and cell wall softening were the most strongly affected. VvABF2 overexpression strongly increased the accumulation of stilbenes that play a role in plant defense and human health (resveratrol and piceid). In addition, the firmness of fruits from tomato (Solanum lycopersicum) plants overexpressing VvABF2 was strongly reduced. These data indicate that VvABF2 is an important transcriptional regulator of ABA-dependent grape berry ripening. PMID:24276949

  5. The Product of the LEU-3 Cistron as a Regulatory Element for the Production of the Leucine Biosynthetic Enzymes of Neurospora

    PubMed Central

    Polacco, Joseph C.; Gross, S. R.

    1973-01-01

    A class of intracistronic (or closely linked) partial reversions of leu-3 mutations has been found to be conditionally constitutive with respect to the synthesis of isopropylmalate isomerase (specified by the leu-2 cistron) and β-isopropylmalate dehydrogenase (specified by the leu-1 cistron), two of the enzymes of leucine biosynthesis in Neurospora. The intermediate level of enzyme production by these leu-3cc mutants is independent of the obligatory inducer effector, α-isopropylmalate, but dependent upon the presence of the branched-chain amino acids, isoleucine, valine and leucine. The properties of leu-3+, leu-3 and leu-3cc in heterokaryons indicate that the transnuclear regulatory activity of the leu-3 product varies specifically as a function of available effector molecules. The information presented suggests that the leu-3 cistron is responsible not only for the production of a "positive" regulatory substance necessary for the expression of the leu-1 and leu-2 cistrons, but that it probably serves also a coordinating role in the expression of many of the genes involved in branched-chain amino acid metabolism. PMID:4744402

  6. MicroRNA-27a is induced by leucine and contributes to leucine-induced proliferation promotion in C2C12 cells.

    PubMed

    Chen, Xiaoling; Huang, Zhiqing; Chen, Daiwen; Yang, Ting; Liu, Guangmang

    2013-01-01

    Leucine, a branched chain amino acid, is well known to stimulate protein synthesis in skeletal muscle. However, the role of leucine in myoblast proliferation remains unclear. In this study, we found that leucine could promote proliferation of C2C12 cells. Moreover, expressions of miR-27a and myostatin (a bona fide target of miR-27a) were upregulated and downregulated, respectively, following leucine treatment. We also found that miR-27a loss-of-function by transfection of a miR-27a inhibitor suppressed the promotion of myoblast proliferation caused by leucine. Our results suggest that miR-27a is induced by leucine and contributes to leucine-induced proliferation promotion of myoblast. PMID:23880856

  7. Plasma and cerebrosponal fluid amino acid levels in diabetic ketoacidosis before and after corrective therapy.

    PubMed

    Aoki, T T; Assal J-P; Manzano, F M; Kozak, G P; Cahill, G F

    1975-05-01

    To evaluate the effect of insulin-saline-bicarbonate therapy on amino acid metabolism in diabetic ketoacidosis, arterial and venous blood samples as well as cerebrospinal fluid (CSF) were obtained from six patients before and after initiation of corrective therapy. Levels of CSF glutamine were decreased while alanine alpha-amino-n-butyrate, valine, isoleucine and leucine were increased significantly compared to a control group composed of six normal, postabsorptive adults free of any neurologic disease. Following therapy, CSF levels of alanine, alpha-amino-n-butyrate, valine, isoleucine, and leucine declined while glutamine levels did not change. Admission arterial plasma levels of the glycogenic amino acids were lower than normal while the branched-chain amino acids were elevated. Plasma alanine and glutamine arterio-venous (A-V) differences across forearm tissue were larger. After four hours of corrective therapy, arterial plasma levels of most of the amino acids had declined sharply and A-V differences for glutamine and alanine were markedly reduced (p smaller than.025 and p smaller than.01, paired t, respectively). Coincident with the decrease in A-V amino acid differences, plasma glucagon and free fatty acid levels declined significantly. These data suggest that the effect exerted by insulin-saline-bicarbonate therapy on amino acid metabolism is manifested by diminished A-V plasma alanine and glutamine differences across forearm tissue. Thus, the role played by the splanchnic bed both before and following corrective measures may be secondary to substrate availability. PMID:805076

  8. Enhanced acetohydroxy acid synthase III activity in an ilvH mutant of Escherichia coli K-12.

    PubMed Central

    Ricca, E; Limauro, D; Lago, C T; de Felice, M

    1988-01-01

    The acetohydroxy acid synthase III isozyme, which catalyzes the first common step in the biosynthesis of isoleucine, leucine, and valine in Escherichia coli K-12, is composed of two subunits, the ilvI and ilvH gene products. A missense mutation in ilvH (ilvH612), which reduced the sensitivity of the enzyme to the end product inhibition by valine, also increased its specific activity and lowered the Km for alpha-acetolactate synthesis. The mutation increased the sensitivity of acetohydroxy acid synthase III to dialysis and heat treatment and reduced the requirement for thiamine pyrophosphate addition to the assay mixture for activity. A strain carrying the ilvH612 mutation grew better than a homologous ilvH+ strain in the presence of leucine. The data indicate that this is a consequence of a more active acetohydroxy acid synthase III isozyme rather than the result of an alteration of the leucine-mediated repression of the ilvIH operon. PMID:3053650

  9. Production of L-(1-/sup 11/C)valine by HPLC resolution

    SciTech Connect

    Washburn, L.C.; Sun, T.T.; Byrd, B.L.; Callahan, A.P.

    1982-01-01

    Based on a recently developed analytical technique, preparative high-performance liquid chromatographic (HPLC) resolution of DL-(1-/sup 11/C)valine has been achieved. A conventional reverse-phase HPLC column and a chiral mobile phase (aqueous solution of L-proline, cupric acetate, and sodium acetate) were used. The copper can be removed from the L-valine fraction by precipitation as the sulfide, and final purification by cation-exchange chromatography yields L-(1-/sup 11/C)valine in a form that is acceptable for clinical positron tomographic studies. This purification method does not remove the L-proline introduced in the resolution process, but added L-proline did not affect the tissue distribution of L-(1-/sup 14/C)valine in rats. We have produced up to 60 mCi of L-(1-/sup 11/C)valine in an overall synthesis and resolution time of 50 min. This procedure should be adaptable to the rapid resolution of other C-/sup 11/-labeled amino acid racemates.

  10. Production of L-(1-/sup 11/C)valine by HPLC resolution

    SciTech Connect

    Washburn, L.C.; Sun, T.T.; Byrd, B.L.; Callahan, A.P.

    1982-01-01

    Based on a recently developed analytical technique, preparative high-performance liquid chromatographic (HPLC) resolution of DL-(1-/sup 11/C)valine has been achieved. A conventional reverse-phase HPLC column and a chiral mobile phase (aqueous solution of L-proline, cupric acetate, and sodium acetate) were used. The copper can be removed from the L-valine fraction by precipitation as the sulfide, and final purification by cation-exchange chromatography yields L-(1-/sup 11/C)valine in a form that is acceptable for clinical positron tomographic studies. This purification method does not remove the L-proline introduced in the resolution process, but added L-proline did not affect the tissue distribution of L-(1-/sup 14/C)valine in rats. We have produced up to 60 mCi of L-(1-/sup 11/C)valine in an overall synthesis and resolution time of 50 min. This procedure should be adapable to the rapid resolution of other C-11-labeled amino acid racemates.

  11. Final report on key comparison CCQM-K55.c (L-(+)-Valine): Characterization of organic substances for chemical purity

    NASA Astrophysics Data System (ADS)

    Westwood, Steven; Josephs, Ralf; Choteau, Tiphaine; Daireaux, Adeline; Wielgosz, Robert; Davies, Stephen; Moad, Michael; Chan, Benjamin; Muñoz, Amalia; Conneely, Patrick; Ricci, Marina; Pires do Rego, Eliane Cristina; Garrido, Bruno C.; Violante, Fernando G. M.; Windust, Anthony; Dai, Xinhua; Huang, Ting; Zhang, Wei; Su, Fuhai; Quan, Can; Wang, Haifeng; Lo, Man-fung; Wong, Wai-fun; Gantois, Fanny; Lalerle, Béatrice; Dorgerloh, Ute; Koch, Matthias; Klyk-Seitz, Urszula-Anna; Pfeifer, Dietmar; Philipp, Rosemarie; Piechotta, Christian; Recknagel, Sebastian; Rothe, Robert; Yamazaki, Taichi; Zakaria, Osman Bin; Castro, E.; Balderas, M.; González, N.; Salazar, C.; Regalado, L.; Valle, E.; Rodríguez, L.; Ángel Laguna, L.; Ramírez, P.; Avila, M.; Ibarra, J.; Valle, L.; Pérez, M.; Arce, M.; Mitani, Y.; Konopelko, L.; Krylov, A.; Lopushanskaya, E.; Tang Lin, Teo; Liu, Qinde; Tong Kooi, Lee; Fernandes-Whaley, Maria; Prevoo-Franzsen, Désirée; Nhlapo, Nontete; Visser, Ria; Kim, Byungjoo; Lee, Hwashim; Kankaew, Pornhatai; Pookrod, Preeyaporn; Sudsiri, Nittaya; Shearman, Kittiya; Ceyhan Gören, Ahmet; Bilsel, Gökhan; Yilmaz, Hasibe; Bilsel, Mine; Çergel, Muhiddin; Gonca Çoskun, Fatma; Uysal, Emrah; Gündüz, Simay; Ün, Ilker; Warren, John; Bearden, Daniel W.; Bedner, Mary; Duewer, David L.; Lang, Brian E.; Lippa, Katrice A.; Schantz, Michele M.; Sieber, John R.

    2014-01-01

    Under the auspices of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) a key comparison, CCQM K55.c, was coordinated by the Bureau International des Poids et Mesures (BIPM) in 2012. Twenty National Measurement Institutes or Designated Institutes and the BIPM participated. Participants were required to assign the mass fraction of valine present as the main component in the comparison sample for CCQM-K55.c. The comparison samples were prepared from analytical grade L-valine purchased from a commercial supplier and used as provided without further treatment or purification. Valine was selected to be representative of the performance of a laboratory's measurement capability for the purity assignment of organic compounds of low structural complexity [molecular weight range 100-300] and high polarity (pKOW > -2). The KCRV for the valine content of the material was 992.0 mg/g with a combined standard uncertainty of 0.3 mg/g. The key comparison reference value (KCRV) was assigned by combination of KCRVs assigned from participant results for each orthogonal impurity class. The relative expanded uncertainties reported by laboratories having results consistent with the KCRV ranged from 1 mg/g to 6 mg/g when using mass balance based approaches alone, 2 mg/g to 7 mg/g using quantitative 1H NMR (qNMR) based approaches and from 1 mg/g to 2.5 mg/g when a result obtained by a mass balance method was combined with a separate qNMR result. The material provided several analytical challenges. In addition to the need to identify and quantify various related amino acid impurities including leucine, isoleucine, alanine and α-amino butyrate, care was required to select appropriate conditions for performing Karl Fischer titration assay for water content to avoid bias due to in situ formation of water by self-condensation under the assay conditions. It also proved to be a challenging compound for purity assignment by qNMR techniques

  12. Leucine Metabolism in T Cell Activation: mTOR Signaling and Beyond.

    PubMed

    Ananieva, Elitsa A; Powell, Jonathan D; Hutson, Susan M

    2016-07-01

    In connection with the increasing interest in metabolic regulation of the immune response, this review discusses current advances in understanding the role of leucine and leucine metabolism in T lymphocyte (T cell) activation. T cell activation during the development of an immune response depends on metabolic reprogramming to ensure that sufficient nutrients and energy are taken up by the highly proliferating T cells. Leucine has been described as an important essential amino acid and a nutrient signal that activates complex 1 of the mammalian target of rapamycin (mTORC1), which is a critical regulator of T cell proliferation, differentiation, and function. The role of leucine in these processes is further discussed in relation to amino acid transporters, leucine-degrading enzymes, and other metabolites of leucine metabolism. A new model of T cell regulation by leucine is proposed and outlines a chain of events that leads to the activation of mTORC1 in T cells. PMID:27422517

  13. DeltapH-Dependent Amino Acid Transport into Plasma Membrane Vesicles Isolated from Sugar Beet (Beta vulgaris L.) Leaves: II. Evidence for Multiple Aliphatic, Neutral Amino Acid Symports.

    PubMed

    Li, Z C; Bush, D R

    1991-08-01

    Proton-coupled aliphatic, neutral amino acid transport was investigated in plasma membrane vesicles isolated from sugar beet (Beta vulgaris L., cv Great Western) leaves. Two neutral amino acid symport systems were resolved based on inter-amino acid transport competition and on large variations in the specific activity of each porter in different species. Competitive inhibition was observed for transport competition between alanine, methionine, glutamine, and leucine (the alanine group) and between isoleucine, valine, and threonine (the isoleucine group). The apparent K(m) and K(i) values were similar for transport competition among amino acids within the alanine group. In contrast, the kinetics of transport competition between these two groups of amino acids did not fit a simple competitive model. Furthermore, members of the isoleucine group were weak transport antagonists of the alanine group. These results are consistent with two independent neutral amino acid porters. In support of that conclusion, the ratio of the specific activity of alanine transport versus isoleucine transport varied from two- to 13-fold in plasma membrane vesicles isolated from different plant species. This ratio would be expected to remain relatively stable if these amino acids were moving through a single transport system and, indeed, the ratio of alanine to glutamine transport varied less than twofold. Analysis of the predicted structure of the aliphatic, neutral amino acids in solution shows that isoleucine, valine, and threonine contain a branched methyl or hydroxyl group at the beta-carbon position that places a dense electron cloud close to the alpha-amino group. This does not occur for the unbranched amino acids or those that branch further away, e.g. leucine. We hypothesize that this structural feature of isoleucine, valine, and threonine results in unfavorable steric interactions with the alanine transport system that limits their flux through this porter. Hydrophobicity and

  14. Dosimetry of D- and L-enantiomers of /sup 11/C-labeled tryptophan and valine

    SciTech Connect

    Washburn, L.C.; Byrd, B.L.; Sun, T.T.; Crook, J.E.; Hubner, K.F.; Coffey, J.L.; Watson, E.E.

    1985-01-01

    We have previously reported the radiation dosimetry of /sup 11/C-labeled DL-tryptophan and DL-valine, as well as clinical pancreatic imaging studies with these agents. Because of significant uptake in both normal pancreas and in pancreatic tumors (thought to be due to the presence of the D-enantiomer), differential diagnosis of pancreatic carcinoma was not feasible. High-performance liquid chromatographic (HPLC) methods were developed for rapid resolution of /sup 11/C-labeled DL-tryptophan and DL-valine. Radiation dose estimates to the various organs in man were calculated for the D- and L-enantiomers of /sup 11/C-labeled tryptophan and valine, based on tissue distribution data in rats. The dose estimates were sufficiently low that 20-mCi doses of each of the enantiomeric amino acids were approved by the FDA for intravenous administration to humans. 21 refs., 3 tabs.

  15. Marginality and needs of dietary valine for broilers fed certain all-vegetable diets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Valine is likely the fourth limiting amino acid in most diets based of corn and soybean meal. However, its exact needs are not well known, and information regarding it is sparse. A series of studies were conducted to validate valine’s limitation in all-vegetable diets fed to broilers, and subseque...

  16. [Alterations in the excess synthesis of riboflavin in Pichia guilliermondii under the influence of branched-chain amino acids].

    PubMed

    Shlee, D

    1977-01-01

    The effect of the branched-chain amino acids: L-valine, L-isoleucine and L-leucine on riboflavin overproduction was studied in the Pichia (Candida) guilliermondii (Cast.) Lang. et G. yeast, L-Val, L-Ile and L-Leu were found to inhibit riboflavin overproduction only under iron-deficient growth conditions. Other amino acids used did not show this effect. In crude extracts of P. guilliermondii the specific activity of the alpha-acetolactate forming enzyme, pH 8.0, is inhibited by L-Val. It is revealed that the activity of alpha-acetolactate synthetase in iron-deficient riboflavin-overproduction cells was exceedingly higher than in the valine-inhibited cells. Under iron deficiency alpha-acetolactate synthetase shows maximal activity after 48 h of growth. It was possible to detect diacetyl (and aceton) in the culture fluid. PMID:867527

  17. Mutants of Salmonella typhimurium with an Altered Leucyl-Transfer Ribonucleic Acid Synthetase

    PubMed Central

    Alexander, Renee R.; Calvo, J. M.; Freundlich, M.

    1971-01-01

    Two trifluoroleucine-resistant mutants of Salmonella typhimurium, strains CV69 and CV117, had an altered leucyl-transfer ribonucleic acid (tRNA) synthetase. The mutant enzymes had higher apparent Km values for leucine (ca. 10-fold) and lower specific activities (ca. twofold) than the parent enzyme when tested in crude extracts. Preparations of synthetase purified ca. 60-fold from the parent and strain CV117 differed sixfold in their leucine Km values. In addition, the mutant enzyme was inactivated faster than the parent enzyme at 50 C. The growth rates of strains CV69 and CV117 at 37 C were not significantly different from that of the parent, whereas at 42 C strain CV69 grew more slowly than the parent. Leucine-, valine-, and isoleucine-forming enzymes were partially derepressed when the mutants were grown in minimal medium; the addition of leucine repressed these enzymes to wild-type levels. During growth in minimal medium, the proportion of leucine tRNA that was charged in the mutants was about 75% of that in the parent. The properties of strain CV117 were shown to result from a single mutation located near gal at minute 18 on the genetic map. These studies suggest that leucyl-tRNA synthetase is involved in repression of the enzymes required for the synthesis of branched-chain amino acids. PMID:4928008

  18. Peripheral metabolism of branched-chain keto acids in patients with chronic renal failure.

    PubMed

    Garibotto, G; Paoletti, E; Fiorini, F; Russo, R; Robaudo, C; Deferrari, G; Tizianello, A

    1993-01-01

    Peripheral tissue metabolism of branched-chain amino acids (BCAA) and branched-chain keto acids (BCKA) in the postabsorptive state was evaluated in 8 patients with chronic renal failure (CRF) and 7 controls by measuring the arterial-deep forearm venous differences for BCAA and BCKA. Arterial whole blood levels of BCAA and BCKA were also measured in an additional 7 patients and 11 controls. In CRF, total BCKA levels are reduced owing to a decrease in ketoisocaproic acid (KICA) and ketoisovaleric acid (KIVA) levels, parallel to changes in BCAA levels, whereas levels of ketomethylvaleric acid (KMVA) are not different from controls. Both in normal conditions and in patients, arterial levels of individual BCAA are directly correlated with arterial levels of the corresponding BCKA. However, in CRF, the ratios of leucine to KICA and of isoleucine to KMVA are increased. A direct correlation between KICA and HCO3- levels is observed. In CRF, the release of leucine and valine as well as of KICA and KMVA from peripheral tissues is reduced, whereas KIVA is neither released nor taken up by the forearm. The lack of KICA release from peripheral tissues likely accounts for its low circulating levels. The depressed peripheral release of leucine associated with the lack of KICA release suggests an increased degradation of leucine which proceeds beyond the transamination step. PMID:8345831

  19. Application and microbial preparation of D-valine.

    PubMed

    Chen, Ming; Shi, Chao; Zhao, Jing; Gao, Ziqing; Zhang, Chunzhi

    2016-10-01

    D-Valine is an important organic chiral source and has extensive industrial application, which is used as intermediate for the synthesis of agricultural pesticides, semi-synthetic veterinary antibiotics and pharmaceutical drugs. Its derivatives have shown great activity in clinical use, such as penicillamine for the treatment of immune-deficiency diseases, and actinomycin D for antitumor therapy. Fluvalinate, a pyrethroid pesticide made from D-valine, is a broad-spectrum insecticide with low mammalian toxicity. Valnemulin, a semi-synthetic pleuromutilin derivative synthesized from D-valine, is an antibiotic for animals. Moreover, D-valine is also used in cell culture for selectively inhibiting fibroblasts proliferation. Due to its widespread application, D-valine is gaining more and more attention and some approaches for D-valine preparation have been investigated. In comparison with other approaches, microbial preparation of D-valine is more competitive and promising because of its high stereo selectivity, mild reaction conditions and environmental friendly process. So far, microbial preparation of D-valine can be mainly classified into three categories: microbial asymmetric degradation of DL-valine, microbial stereoselective hydrolysis of N-acyl-DL-valine by D-aminoacylase, and microbial specific hydrolysis of DL-5-isopropylhydantoin by D-hydantoinase coupled with D-carbamoylase. In this paper, the industrial application of D-valine and its microbial preparation are reviewed. PMID:27565781

  20. Amino Acid Metabolism of Thermoanaerobacter Strain AK90: The Role of Electron-Scavenging Systems in End Product Formation

    PubMed Central

    Scully, Sean Michael; Orlygsson, Johann

    2015-01-01

    The catabolism of the 20 amino acids by Thermoanaerobacter strain AK90 (KR007667) was investigated under three different conditions: as single amino acids without an electron-scavenging system, in the presence of thiosulfate, and in coculture with a hydrogenotrophic methanogen. The strain degraded only serine without an alternative electron acceptor but degraded 11 amino acids (alanine, cysteine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tyrosine, and valine) under both of the electron-scavenging systems investigated. Acetate was the dominant end product from alanine, cysteine, lysine, serine, and threonine under electron-scavenging conditions. The branched-chain amino acids, isoleucine, leucine, and valine, were degraded to their corresponding fatty acids under methanogenic conditions and to a mixture of their corresponding fatty acids and alcohols in the presence of thiosulfate. The partial pressure of hydrogen seems to be of importance for the branched-chain alcohol formation. This was suggested by low but detectable hydrogen concentrations at the end of cultivation on the branched-chain amino acid in the presence of thiosulfate but not when cocultured with the methanogen. A more detailed examination of the role of thiosulfate as an electron acceptor was performed with Thermoanaerobacter ethanolicus (DSM 2246) and Thermoanaerobacter brockii (DSM 1457). PMID:26413318

  1. Anticodon-independent aminoacylation of an RNA minihelix with valine.

    PubMed Central

    Frugier, M; Florentz, C; Giegé, R

    1992-01-01

    Minihelices mimicking the amino acid acceptor and anticodon branches of yeast tRNA(Val) have been synthesized by in vitro transcription of synthetic templates. It is shown that a minihelix corresponding to the amino acid acceptor branch and containing solely a valine-specific identity nucleotide can be aminoacylated by yeast valyl-tRNA synthetase. Its charging ability is lost after mutating this nucleotide. This ability is stimulated somewhat by the addition of a second hairpin helix that mimicks the anticodon arm, which suggests that information originating from the anticodon stem-loop can be transmitted to the active site of the enzyme by the core of the protein. Images PMID:1570324

  2. Double-blind, placebo-controlled pilot trial of L-Leucine-enriched amino-acid mixtures on body composition and physical performance in men and women aged 65–75 years

    PubMed Central

    Ispoglou, T; White, H; Preston, T; McElhone, S; McKenna, J; Hind, K

    2016-01-01

    Background/Objectives: Adequate protein intake is essential to retaining muscle and maintaining physical function, especially in the elderly, and L-Leucine has received attention as an essential amino acid (EAA) that enhances protein retention. The study's aim was to compare the efficacy of EAA mixtures on lean tissue mass (LTM) and functional performance (FP) in a healthy elderly population. Subjects/Methods: Thirty-six subjects (65–75 years) volunteered to receive capsules with EAAs (Groups A and B containing 20% and 40% L-Leucine, respectively) or placebo (lactose containing 0% L-Leucine, Group C) for 12 weeks. The daily amount ranged from 11 to 21 g (0.21 g/ kg/day) and was taken in two equal dosages alongside food, morning and evening. Main outcomes measured before and after intervention were LTM and FP (30-s arm-curl test; 30-s chair-stand test (30-CST); 6-min walk test (6-WT); and handgrip strength). Secondary outcomes included dietary intakes and physical activity. Results: Twenty-five subjects (11 male and 14 female) completed the study (Group A, n=8; Group B, n=8; Group C, n=9). Gains associated with medium effect sizes were noted in LTM (Group B, 1.1 ±1.1%, P=0.003) and FP (Group A in 30-CST (11.0±11.5%, P=0.02) and 6-WT (8.8±10.0%, P=0.02); Group B in 6-WT (5.8±6.6%, P=0.03) and a trend in 30-CST (13.2±16.0, P=0.06)). Significant differences between groups were not observed in secondary outcomes. Conclusions: Twice-daily supplementation of EAAs containing 20% or 40% L-Leucine improved aspects of functional status and at the higher level improved LTM. Further work to establish change in a larger sample and palatable supplemental format is now required. PMID:26081485

  3. Postoperative enteral hyperalimentation results in earlier elevation of serum branched-chain amino acid levels.

    PubMed

    Moss, G; Naylor, E D

    1994-07-01

    To objectively document the immediate maintenance and successful exploitation of postoperative gastrointestinal (GI) function, elemental diet was infused into the more distal duodenum of 30 cholecystectomy patients at 300 kcal per hour, beginning on arrival at the recovery room. Approximately 4,600 kcal and 190 grams of amino acids were absorbed during the initial 16 hours. Serum branched-chain amino acids (BCAAs) had risen above basal levels at 4 hours, statistically significant only for leucine (+64%). The higher concentrations had reached statistical significance for all BCAAs by 6 hours, when leucine had risen by 83%, isoleucine by 54%, and valine by 47%. The elevated BCAA and glucose levels sustained throughout the hyperalimentation period objectively verify that postoperative GI function can be safely exploited, and may contribute to improved wound healing and sepsis resistance. PMID:8024096

  4. Structural basis for leucine sensing by the Sestrin2-mTORC1 pathway

    PubMed Central

    Saxton, Robert A.; Knockenhauer, Kevin E.; Wolfson, Rachel L.; Chantranupong, Lynne; Pacold, Michael E.; Wang, Tim; Schwartz, Thomas U.; Sabatini, David M.

    2015-01-01

    Eukaryotic cells coordinate growth with the availability of nutrients through mTOR complex 1 (mTORC1), a master growth regulator. Leucine is of particular importance and activates mTORC1 via the Rag GTPases and their regulators GATOR1 and GATOR2. Sestrin2 interacts with GATOR2 and is a leucine sensor. We present the 2.7-Å crystal structure of Sestrin2 in complex with leucine. Leucine binds through a single pocket that coordinates its charged functional groups and confers specificity for the hydrophobic side chain. A loop encloses leucine and forms a lid-latch mechanism required for binding. A structure-guided mutation in Sestrin2 that decreases its affinity for leucine leads to a concomitant increase in the leucine concentration required for mTORC1 activation in cells. These results provide a structural mechanism of amino acid sensing by the mTORC1 pathway. PMID:26586190

  5. Isolation and Partial Characterization of Temperature-Sensitive Escherichia coli Mutants with Altered Leucyl- and Seryl-Transfer Ribonucleic Acid Synthetases

    PubMed Central

    Low, B.; Gates, F.; Goldstein, T.; Söll, D.

    1971-01-01

    Two temperature-sensitive mutants of Escherichia coli have been found in which the conditional growth is a result of a thermosensitive leucyl-transfer ribonucleic acid (tRNA) synthetase and seryl-tRNA synthetase, respectively. The corresponding genetic loci, leuS and serS, cotransduce with lip and serC, respectively. As a result of the mutationally altered leucyl-tRNA synthetase, some leucine-, valine-, and isoleucine-forming enzymes were derepressed. Thus, leucyl-tRNA synthetase is involved in the repression of the enzymes needed for the synthesis of branched-chain amino acids. PMID:4942762

  6. Chiroptical study of α-aliphatic amino acid films in the vacuum ultraviolet region.

    PubMed

    Tanaka, Masahito; Yagi-Watanabe, Kazutoshi; Kaneko, Fusae; Nakagawa, Kazumichi

    2010-11-11

    A series of natural circular dichroism (CD) and absorption spectra for films of α-aliphatic amino acids--such as alanine, aminobutyric acid, norvaline, norleucine, valine, leucine, and isoleucine--in the vacuum ultraviolet (VUV) region were observed with the absolute values of optical constants at the undulator-based CD beamline TERAS BL5. Preliminary predictions of some CD spectra were also performed, based on quantum-chemical calculations using the crystal structure. Although the absorption spectra show similar features to each other, significant differences between the CD spectra were found, especially in the 7-8 eV region. The CD spectra of aliphatic amino acids with branched alkyl groups in the side-chain--such as valine, leucine, and isoleucine--exhibit strong negative CD peaks in this energy region. In contrast, the corresponding CD peaks were weak or absent in the spectra of amino acids with straight alkyl groups. Our simple calculation, and the absorption spectra of alkanes, suggest that this difference partly originates from the contribution of the alkyl group. Clear discrepancies between the CD spectra of these amino acids in solutions and those in the solid state were also observed; this is probably caused by the different molecular structures in each state. Our results clearly indicated that CD spectra in the VUV region were very sensitive to the conformations of chiral molecules. PMID:20958008

  7. Valine-Resistance, a Potential Marker in Plant Cell Genetics. II. Optimization of Uv Mutagenesis and Selection of Valine-Resistant Colonies Derived from Tobacco Mesophyll Protoplasts.

    PubMed

    Grandbastien, M A; Bourgin, J P; Caboche, M

    1985-02-01

    The induction and selection of valine-resistant mutants from haploid tobacco (Nicotiana tabacum L.) mesophyll protoplast-derived cells have been studied. Using cells from an original mutant plant obtained previously, we performed reconstruction experiments in order to determine the best conditions for the recovery of resistant cells among a population of sensitive cells. Optimal selective conditions were shown to depend on various factors including cell density, time of addition of valine and seasonal variations affecting the mother plants.-Using cell densities of approximately 10( 4) cells/ml, we defined efficient selective conditions: more than 25% of the putative mutant clones selected from UV-mutagenized protoplasts were reproducibly confirmed to be valine resistant. Further characterization of some regenerated mutant plants indicated that valine-resistance was associated with an uptake deficiency, as in the case of the original mutant plant of the Val(r)-2 line used for reconstruction experiments. Spontaneous mutation rates for valine-resistance were below accurately detectable levels, i.e., less than 10(-6) per cell per generation. Induced mutation frequency varied nonlinearily with UV dose from 10(-5) to 5 x 10(-4) resistant clones per surviving colony. Two independent loci (vr2 and vr3) were previously shown to be involved in valine-resistance due to amino acid uptake deficiency. Haploid tobacco plants were produced through anther culture from an F(1) double-heterozygous plant obtained from a cross between the original mutant plant and a wild-type plant. Study of the level of resistance to valine of protoplast-derived cells allowed the classification of these haploid plants in four types: sensitive, resistant and two intermediary resistant types believed to result from the presence of a mutant allele at only one of the two loci involved. The frequencies of UV-induced mutations in cells derived from haploid plants of one of the intermediary types were

  8. Relationship between surface concentration of L-leucine and bulk powder properties in spray dried formulations.

    PubMed

    Mangal, Sharad; Meiser, Felix; Tan, Geoffrey; Gengenbach, Thomas; Denman, John; Rowles, Matthew R; Larson, Ian; Morton, David A V

    2015-08-01

    The amino acid L-leucine has been demonstrated to act as a lubricant and improve the dispersibility of otherwise cohesive fine particles. It was hypothesized that optimum surface L-leucine concentration is necessary to achieve optimal surface and bulk powder properties. Polyvinylpyrrolidone was spray dried with different concentration of L-leucine and the change in surface composition of the formulations was determined using X-ray photoelectron spectroscopy (XPS) and time of flight-secondary ion mass spectrometry (ToF-SIMS). The formulations were also subjected to powder X-ray diffraction analysis in order to understand the relationship between surface concentration and solid-state properties of L-leucine. In addition, the morphology, surface energy and bulk cohesion of spray dried formulations were also assessed to understand the relation between surface L-leucine concentration and surface and bulk properties. The surface concentration of L-leucine increased with higher feed concentrations and plateaued at about 10% L-leucine. Higher surface L-leucine concentration also resulted in the formation of larger L-leucine crystals and not much change in crystal size was noted above 10% L-leucine. A change in surface morphology of particles from spherical to increasingly corrugated was also observed with increasing surface l-leucine concentration. Specific collapsed/folded over particles were only seen in formulations with 10% or higher l-leucine feed concentration suggesting a change in particle surface formation process. In addition, bulk cohesion also reduced and approached a minimum with 10% L-leucine concentration. Thus, the surface concentration of L-leucine governs particle formation and optimum surface L-leucine concentration results in optimum surface and bulk powder properties. PMID:26007290

  9. NMR analyses of the conformations of L-isoleucine and L-valine bound to Escherichia coli isoleucyl-tRNA synthetase

    SciTech Connect

    Kohda, D.; Kawai, G.; Yokoyama, S.; Kawakami, M.; Mizushima, S.; Miyazawa, T.

    1987-10-06

    The 400-MHz /sup 1/H NMR spectra of L-isoleucine and L-valine were measured in the presence of Escherichia coli isoleucyl-tRNA synthetase (IleRS). Because of chemical exchange of L-isoleucine or L-valine between the free state and the IleRS-bound state, a transferred nuclear Overhauser effect (TRNOE) was observed among proton resonances of L-isoleucine or L-valine. However, in the presence of isoleucyl adenylate tightly bound to the amino acid activation site of IleRS, no TRNOE for L-isoleucine or L-valine was observed. This indicates that the observed TRNOE is due to the interaction of L-isoleucine or L-valine with the amino acid activation site of IleRS. The conformations of these amino acids in the amino acid activation site of IleRS were determined by the analyses of time dependences of TRNOEs and TRNOE action spectra. The IleRS-bound L-isoleucine takes the gauche/sup +/ form about the C/sub ..cap alpha../-C/sub ..beta../ bond and the trans form about the C/sub ..beta../-C/sub ..gamma../sub 1// bond. The IleRS-bound L-valine takes the guache/sup -/ form about the C/sub ..cap alpha../-C/sub ..beta../ bond. Thus, the conformation of the IleRS-bound L-valine is the same as that of IleRS-bound L-isoleucine except for the delta-methyl group. The side chain of L-isoleucine or L-valine lies in an aliphatic hydrophobic pocket of the active site of IleRS. Such hydrophobic interaction with IleRS is more significant for L-isoleucine than for L-valine. The TRNOE analysis is useful for studying the amino acid discrimination mechanism of aminoacyl-tRNA synthetases.

  10. Age Attenuates Leucine Oxidation after Eccentric Exercise

    PubMed Central

    Kullman, E. L.; Campbell, W. W.; Krishnan, R. K.; Yarasheski, K. E.; Evans, W. J.; Kirwan, J. P.

    2013-01-01

    Aging may alter protein metabolism during periods of metabolic and physiologic challenge. The purpose of this study was to assess the effects of age on whole-body amino acid turnover in response to eccentric exercise and hyperglycemia-induced hyperinsulinemia. 16 healthy men were divided into young (N = 8) and older (N = 8) groups. Protein metabolism was assessed using a [1-13C]-leucine isotopic tracer approach. Measures were obtained under fasted basal conditions and during 3-h hyperglycemic clamps that were performed without (control) and 48 h after eccentric exercise. Exercise reduced leucine oxidation in the younger men (P < 0.05), but not in older men. Insulin sensitivity was inversely correlated with leucine oxidation (P < 0.05), and was lower in older men (P < 0.05). Healthy aging is associated with an impaired capacity to adjust protein oxidation in response to eccentric exercise. The decreased efficiency of protein utilization in older men may contribute to impaired maintenance, growth, and repair of body tissues with advancing age. PMID:23325713

  11. Effects of leucine supplemented diet on intestinal absorption in tumor bearing pregnant rats

    PubMed Central

    Ventrucci, Gislaine; de Mello, Maria Alice Roston; Gomes-Marcondes, Maria Cristina Cintra

    2002-01-01

    Background It is known that amino acid oxidation is increased in tumor-bearing rat muscles and that leucine is an important ketogenic amino acid that provides energy to the skeletal muscle. Methods To evaluate the effects of a leucine supplemented diet on the intestinal absorption alterations produced by Walker 256, growing pregnant rats were distributed into six groups. Three pregnant groups received a normal protein diet (18% protein): pregnant (N), tumor-bearing (WN), pair-fed rats (Np). Three other pregnant groups were fed a diet supplemented with 3% leucine (15% protein plus 3% leucine): leucine (L), tumor-bearing (WL) and pair-fed with leucine (Lp). Non pregnant rats (C), which received a normal protein diet, were used as a control group. After 20 days, the animals were submitted to intestinal perfusion to measure leucine, methionine and glucose absorption. Results Tumor-bearing pregnant rats showed impairment in food intake, body weight gain and muscle protein content, which were less accentuated in WL than in WN rats. These metabolic changes led to reduction in both fetal and tumor development. Leucine absorption slightly increased in WN group. In spite of having a significant decrease in leucine and methionine absorption compared to L, the WL group has shown a higher absorption rate of methionine than WN group, probably due to the ingestion of the leucine supplemented diet inducing this amino acid uptake. Glucose absorption was reduced in both tumor-bearing groups. Conclusions Leucine supplementation during pregnancy in tumor-bearing rats promoted high leucine absorption, increasing the availability of the amino acid for neoplasic cells and, mainly, for fetus and host utilization. This may have contributed to the better preservation of body weight gain, food intake and muscle protein observed in the supplemented rats in relation to the non-supplemented ones. PMID:11955290

  12. 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

  13. A new physiological role for Pdr12p in Saccharomyces cerevisiae: export of aromatic and branched-chain organic acids produced in amino acid catabolism.

    PubMed

    Hazelwood, Lucie A; Tai, Siew Leng; Boer, Viktor M; de Winde, Johannes H; Pronk, Jack T; Daran, Jean Marc

    2006-09-01

    Saccharomyces cerevisiae can use a broad range of compounds as sole nitrogen source. Many amino acids, such as leucine, tyrosine, phenylalanine and methionine, are utilized through the Ehrlich pathway. The fusel acids and alcohols produced from this pathway, along with their derived esters, are important contributors to beer and wine flavor. It is unknown how these compounds are exported from the cell. Analysis of nitrogen-source-dependent transcript profiles via microarray analysis of glucose-limited, aerobic chemostat cultures revealed a common upregulation of PDR12 in cultures grown with leucine, methionine or phenylalanine as sole nitrogen source. PDR12 encodes an ABC transporter involved in weak-organic-acid resistance, which has hitherto been studied in the context of resistance to exogenous organic acids. The hypothesis that PDR12 is involved in export of natural products of amino acid catabolism was evaluated by analyzing the phenotype of null mutants in PDR12 or in WAR1, its positive transcriptional regulator. The hypersensitivity of the pdr12Delta and war1Delta strains for some of these compounds indicates that Pdr12p is involved in export of the fusel acids, but not the fusel alcohols derived from leucine, isoleucine, valine, phenylalanine and tryptophan. PMID:16911515

  14. Effects of branched-chain amino acid supplementation on plasma concentrations of free amino acids, insulin, and energy substrates in young men.

    PubMed

    Zhang, Yi; Kobayashi, Hisamine; Mawatari, Kazunori; Sato, Juichi; Bajotto, Gustavo; Kitaura, Yasuyuki; Shimomura, Yoshiharu

    2011-01-01

    The present study was conducted to examine alterations in the concentrations of plasma free amino acids, glucose, insulin, free fatty acids (FFAs), and urea nitrogen induced by branched-chain amino acid (BCAA) supplementation in young men. Overnight-fasted subjects ingested drinks containing 1 or 5 g of a BCAA mixture (weight ratio of 1 : 2.3 : 1.2 for isoleucine : leucine : valine), and blood was intermittently collected for 3 h after ingestion. Ingestion of the BCAA mixture resulted in significant increases in the plasma concentrations of individual BCAAs, corresponding to the amounts of amino acids ingested. On the other hand, plasma concentrations of methionine and aromatic amino acids tended to decrease in the trial with 5 g BCAAs, suggesting that BCAA ingestion affects the metabolism of these amino acids. The ingestion of BCAAs temporarily increased plasma insulin levels and affected plasma concentrations of FFAs, but had almost no effect on glucose or urea nitrogen. PMID:21512300

  15. Design and synthesis of human ABCB1 (P-glycoprotein) inhibitors by peptide coupling of diverse chemical scaffolds on carboxyl and amino termini of (S)-valine-derived thiazole amino acid.

    PubMed

    Singh, Satyakam; Prasad, Nagarajan Rajendra; Chufan, Eduardo E; Patel, Bhargav A; Wang, Yi-Jun; Chen, Zhe-Sheng; Ambudkar, Suresh V; Talele, Tanaji T

    2014-05-22

    P-glycoprotein (P-gp) serves as a therapeutic target for the development of multidrug resistance reversal agents. In this study, we synthesized 21 novel compounds by peptide coupling at corresponding carboxyl and amino termini of (S)-valine-based bis-thiazole and monothiazole derivatives with diverse chemical scaffolds. Using calcein-AM efflux assay, we identified compound 28 (IC50 = 1.0 μM) carrying 3,4,5-trimethoxybenzoyl and 2-aminobenzophenone groups, respectively, at the amino and carboxyl termini of the monothiazole zwitter-ion. Compound 28 inhibited the photolabeling of P-gp with [(125)I]-iodoarylazidoprazosin with IC50 = 0.75 μM and stimulated the basal ATP hydrolysis of P-gp in a concentration-dependent manner (EC50 ATPase = 0.027 μM). Compound 28 at 3 μM reduced resistance in cytotoxicity assay to paclitaxel in P-gp-expressing SW620/Ad300 and HEK/ABCB1 cell lines. Biochemical and docking studies showed site-1 to be the preferable binding site for 28 within the drug-binding pocket of human P-gp. PMID:24773054

  16. New Amino Acid Regulatory Locus Having Unusual Properties in Heterozygous Merodiploids

    PubMed Central

    Kline, Ellis L.

    1972-01-01

    Spontaneous mutants of Escherichia coli B/r resistant to 5′,5′,5′,-trifluoro-dl-leucine contain defects in a gene which maps to the left of the threonine region. Low-level constitutive expression of the isoleucine-valine and leucine operons is caused by this mutation in haploid strains. This is in contrast to extremely high levels of gene expression in the heterozygous merodiploids (F' wild type/mutant allele). The properties of these mutants define a new locus and suggest that it encodes a subunit protein which is involved in the repression of the structural genes for the branched-chain amino acid pathways. Images PMID:4555405

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

    SciTech Connect

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

    1988-03-15

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

  18. Measurement of local rates of brain protein synthesis by quantitative autoradiography: validation with L-(/sup 3/H)valine

    SciTech Connect

    Dwyer, B.E.; Donatoni, P.; Wasterlain, C.G.

    1982-12-01

    Following the injection of 4-day old rats with 150 mM L-(3,4-/sup 3/H)valine (10 mumol/g, IP) the incorporation of /sup 3/H into protein was linear 2 hours. Valine specific activity in the brain acid-soluble fraction was constant between 30 and 120 min after injection with a mean value of 82.3% of the injectate. Significant amounts of tritated metabolites accumulated in the brain acid-soluble fraction (41.4% of radioactivity at 120 min) but do not prove an impediment to measuring rates of protein synthesis. The rate of protein synthesis in cerebral cortex of the 4-day old rat was measured by quantitative autoradiography using (/sup 3/H)valine and /sup 3/H-sensitive film. The measured rate shows excellent agreement with that found previously using L-(1-/sup 14/C)valine. Our results suggest that (/sup 3/H)valine can be a useful precursor to measure local rates of brain protein synthesis by quantitative autoradiography.

  19. 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.

  20. The Regulation of Essential Amino Acid Synthesis and Accumulation in Plants.

    PubMed

    Galili, Gad; Amir, Rachel; Fernie, Alisdair R

    2016-04-29

    Although amino acids are critical for all forms of life, only proteogenic amino acids that humans and animals cannot synthesize de novo and therefore must acquire in their diets are classified as essential. Nine amino acids-lysine, methionine, threonine, phenylalanine, tryptophan, valine, isoleucine, leucine, and histidine-fit this definition. Despite their nutritional importance, several of these amino acids are present in limiting quantities in many of the world's major crops. In recent years, a combination of reverse genetic and biochemical approaches has been used to define the genes encoding the enzymes responsible for synthesizing, degrading, and regulating these amino acids. In this review, we describe recent advances in our understanding of the metabolism of the essential amino acids, discuss approaches for enhancing their levels in plants, and appraise efforts toward their biofortification in crop plants. PMID:26735064

  1. Biochemical Characterization of Branched Chain Amino Acids Uptake in Trypanosoma cruzi.

    PubMed

    Manchola, Nubia C; Rapado, Ludmila N; Barisón, María J; Silber, Ariel M

    2016-05-01

    Trypanosoma cruzi is the etiological agent of Chagas disease. During its life cycle, it alternates among vertebrate and invertebrate hosts. Metabolic flexibility is a main biochemical characteristic of this parasite, which is able to obtain energy by oxidizing a variety of nutrients that can be transported from the extracellular medium. Moreover, several of these metabolites, more specifically amino acids, have a variety of functions beyond being sources of energy. Branched chain amino acids (BCAA), beyond their role in ATP production, are involved in sterol biosynthesis; for example, leucine is involved as a negative regulator of the parasite differentiation process occurring in the insect midgut. BCAA are essential metabolites in most nonphotosynthetic eukaryotes, including trypanosomes. In view of this, the metabolism of BCAA in T. cruzi depends mainly on their transport into the cell. In this work, we kinetically characterized the BCAA transport in T. cruzi epimastigotes. Our data point to BCAA as being transported by a single saturable transport system able to recognize leucine, isoleucine and valine. In view of this, we used leucine to further characterize this system. The transport increased linearly with temperature from 10 to 45 °C, allowing the calculation of an activation energy of 51.30 kJ/mol. Leucine uptake was an active process depending on ATP production and a H(+) gradient, but not on a Na(+) or K(+) gradient at the cytoplasmic membrane level. PMID:26496801

  2. Human milk nonprotein nitrogen components: changing patterns of free amino acids and urea in the course of early lactation.

    PubMed

    Harzer, G; Franzke, V; Bindels, J G

    1984-08-01

    Free amino acids and urea were analyzed in 78 human milk samples obtained during the first 5 wk of lactation from 10 mothers delivering at term. Significant differences (p less than 0.05) in the concentrations between colostral and mature milk were found for glutamic acid, glutamine, alanine, glycine, cystine, and phosphoethanolamine which increased, and with serine, phosphoserine, aspartic acid + asparagine, arginine, lysine, isoleucine, phenylalanine, proline, methionine, tryptophan, and beta-alanine which decreased. Some of these changes occurred within the first 5 days of lactation, so that differences between transitional and mature milk became negligible (glutamic acid, alanine, and serine, aspartic acid + asparagine, lysine, isoleucine, methionine, tryptophan, respectively). No significant differences between any of the three stages of lactation were found regarding the concentrations of total free amino acids, urea, taurine, threonine, valine, leucine, histidine, and tyrosine. Possible relevances for free amino acids, including nonprotein ones, in human milk are discussed. PMID:6147084

  3. Leucine Transport in Cells Isolated from Cold-Hardened and Nonhardened Winter Rye 1

    PubMed Central

    Barran, Leslie R.; Singh, Jas

    1982-01-01

    The properties of the leucine transport systems of cells isolated from dark-grown cold-hardened and nonhardened winter rye (Secale cereale L. cv. Puma) epicotyls were remarkably similar. After 1 hour of incubation, leucine was accumulated in the cells 80- to 100-fold above that of the external medium, but the transported leucine was not metabolized. Approximately one-third of the accumulated leucine was present in the vacuole after 40 minutes of incubation. At 25°C, efflux of leucine from the vacuole was 6 to 10 times slower than it was from the cytoplasm, while at 5°C efflux from the cells was inhibited. The apparent Km and Vmax for leucine uptake for both types of cells were of the order of 20 to 60 micromolar and 0.5 to 1.3 nanomoles per minute per 106 cells. The pH and temperature optima for both types of cells were 5 and 25°C, respectively. The leucine transport system for these cells was relatively specific for amino acids lacking either bulky or charged groups on the amino acid side chains. Arrhenius plots for leucine uptake by hardened and nonhardened cells showed discontinuities at 13°C, and the energies of activation were similar. The results suggests that biochemical changes which occur in rye cells upon cold hardening did not result in an observable perturbation of the properties of the leucine transport system. PMID:16662298

  4. Electron ionization and dissociation of aliphatic amino acids

    NASA Astrophysics Data System (ADS)

    Papp, P.; Shchukin, P.; Kočíšek, J.; Matejčík, Š.

    2012-09-01

    We present experimental and theoretical study of electron ionization and dissociative ionization to the gas phase amino acids valine, leucine, and isoleucine. A crossed electron/molecular beams technique equipped with quadrupole mass analyzer has been applied to measure mass spectra and ion efficiency curves for formation of particular ions. From experimental data the ionization energies of the molecules and the appearance energies of the fragment ions were determined. Ab initio calculations (Density Functional Theory and G3MP2 methods) were performed in order to calculate the fragmentation paths and interpret the experimental data. The experimental ionization energies of parent molecules [P]+ 8.91 ± 0.05, 8.85 ± 0.05, and 8.79 ± 0.05 eV and G3MP2 ionization energies (adiabatic) of 8.89, 8.88, and 8.81 eV were determined for valine, leucine, and isoleucine, respectively, as well as the experimental and theoretical threshold energies for dissociative ionization channels. The comparison of experimental data with calculations resulted in identification of the ions as well as the neutral fragments formed in the dissociative reactions. Around 15 mass/charge ratio fragments were identified from the mass spectra by comparison of experimental appearance energies with calculated reaction enthalpies for particular dissociative reactions.

  5. Raman spectroscopic study of DL valine under pressure up to 20 GPa

    NASA Astrophysics Data System (ADS)

    Rêgo, F. S. C.; Lima, J. A.; Freire, P. T. C.; Melo, F. E. A.; Mendes Filho, J.; Polian, A.

    2016-04-01

    DL-valine crystal was studied by Raman spectroscopy under hydrostatic pressure using a diamond anvil cell from ambient pressure up to 19.4 GPa in the spectral range from 40 to 3300 cm-1. Modifications in the spectra furnished evidence of the occurrence of two structural phase transitions undergone by this racemic amino acid crystal. The classification of the vibrational modes, the behavior of their wavenumber as a function of the pressure and the reversibility of the phase transitions are discussed.

  6. Photosensitizing effect of cations on amino acids and peptides.

    PubMed

    Bogdanova, N P; Khenokh, M A

    1969-01-01

    In connection with a study of the chemical evolution of abiogenically synthesized organic compounds on primitive Earth and the physical conditions of other planets, this paper reports the experimental results obtained by the photolysis of solutions of aliphatic amino acids (glycine, alanine, valine, leucine, n. leucine) and peptides in the atmosphere of the air, N2, Ar and CO2 in the presence of the most simple photocatalyzers-cations of sulphates. The evidence shows that the photochemical conversion of NH2 acids depends on the content of the atmosphere. The decay of NH2-group is most active in air. N2 and Ar exert no significant influence on deamination, whereas in the atmosphere of CO2 the formation of ammonia in valine, for example, was only 29 per cent of its total amount during photolysis in the air. Cu2+ and Fe2+ catalyzed while Al3+ inhibited the ammonia excretion. The formation of acetaldehyde during alanine photolysis was actually independent from the atmosphere of N2 and was inhibited in Ar and CO2. Oxydative processes inducing the formation of glyoxalic acid and formaldehyde were sharply inhibited in Ar, N2 and CO2. Under the influence of ultraviolet light of the decay of NH2-acids is also accompanied by the formation of new NH2-acids. The photosensitizing effect of cations induces a rupture of -CO-NH-bonds in peptides and, provided heavy radiation doses, prevents the formation of new NH2-acids. The longer the dipeptide chain, the more significant the quantum yield of its decomposition. The photolysis of dipeptides, leading to their decay, does not necessarily induce a hydrolytic rupture of -CO-NH-bonds resulting in the formation of three amino acids. The results obtained permit approaching problems concerning the effect of the gas content of the atmosphere and various cations (photocatalyzers) on photolytic conversion of abiogenically synthesized and biogenically significant substances, amino acids for example, at the action of ultraviolet light. PMID

  7. Quantitative measurements of regional glucose utilization and rate of valine incorporation into proteins by double-tracer autoradiography in the rat brain tumor model

    SciTech Connect

    Kirikae, M.; Diksic, M.; Yamamoto, Y.L.

    1989-02-01

    We examined the rate of glucose utilization and the rate of valine incorporation into proteins using 2-(/sup 18/F)fluoro-2-deoxyglucose and L-(1-14C)-valine in a rat brain tumor model by quantitative double-tracer autoradiography. We found that in the implanted tumor the rate of valine incorporation into proteins was about 22 times and the rate of glucose utilization was about 1.5 times that in the contralateral cortex. (In the ipsilateral cortex, the tumor had a profound effect on glucose utilization but no effect on the rate of valine incorporation into proteins.) Our findings suggest that it is more useful to measure protein synthesis than glucose utilization to assess the effectiveness of antitumor agents and their toxicity to normal brain tissue. We compared two methods to estimate the rate of valine incorporation: kinetic (quantitation done using an operational equation and the average brain rate coefficients) and washed slices (unbound labeled valine removed by washing brain slices in 10% trichloroacetic acid). The results were the same using either method. It would seem that the kinetic method can thus be used for quantitative measurement of protein synthesis in brain tumors and normal brain tissue using (/sup 11/C)-valine with positron emission tomography.

  8. Differential effects of long-term leucine infusion on tissue protein synthesis in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leucine is unique among the amino acids in its ability to promote protein synthesis by activating translation initiation via the mammalian target of rapamycin (mTOR) pathway. Previously, we showed that leucine infusion acutely stimulates protein synthesis in fast-twitch glycolytic muscle of neonatal...

  9. 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

  10. The 213-amino-acid leucine-rich repeat region of the listeria monocytogenes InlB protein is sufficient for entry into mammalian cells, stimulation of PI 3-kinase and membrane ruffling.

    PubMed

    Braun, L; Nato, F; Payrastre, B; Mazié, J C; Cossart, P

    1999-10-01

    The Listeria monocytogenes InlB protein is a 630-amino-acid surface protein that mediates entry of the bacterium into a wide variety of cell types, including hepatocytes, fibroblasts and epithelial cells such as Vero, HEp-2 and HeLa cells. Invasion stimulates host proteins tyrosine phosphorylation, PI 3-kinase activity and rearrangements in the actin cytoskeleton. We previously showed that InlB is sufficient for entry of InlB-coated latex beads into cells and recent results indicate that purified InlB can stimulate PI 3-kinase activity and is thus the first bacterial agonist of this lipid kinase. In this study, we identified the region of InlB responsible for entry and stimulation of signal transduction events. Eight monoclonal antibodies directed against InlB were raised and, of those, five inhibited bacterial entry. These five antibodies recognized epitopes within the leucine-rich repeat (LRR) region and/or the inter-repeat (IR) region. InlB-staphylococcal protein A (SPA) fusion proteins and recombinant InlB derivatives were generated and tested for their capacity to mediate entry into cultured mammalian cells. All the InlB derivatives that carried the amino-terminal 213-amino-acid LRR region conferred invasiveness to the normally non-invasive bacterium L. innocua or to inert latex beads and the corresponding purified polypeptides inhibited bacterial entry. In addition, the 213-amino-acid LRR region was able to stimulate PI 3-kinase activity and changes in the actin cytoskeleton (membrane ruffling). These properties were not detected with purified internalin, another invasion protein of L. monocytogenes that displays LRRs similar to those of InlB. Taken together, these results show that the first 213 amino acids of InlB are critical for its specific properties. PMID:10540282

  11. The mechanism of transfer for L-leucine into the vascular bed of the Anuran small intestine.

    PubMed Central

    Cheeseman, C I

    1981-01-01

    1. The vascularly perfused small intestine of Rana pipiens was used to investigate the movement of the amino acid L-leucine from the epithelium into the vascular bed. It was found that only a few amino acids when present in the lumen inhibited the wash-out leucine into the vascular bed. The series of amino acids which had this effect belonged to the group previously shown to be transported by 'L-type' carrier systems. 2. Nearly all amino acids when present in the lumen accelerated the flux of leucine from the vascular bed to the lumen and there was little correlation between the amino acids which caused this effect and those which inhibited leucine wash-out into the vascular bed. Replacement of luminal sodium also promoted serosal-to-mucosal leucine flux. 3. The effect of the presence of amino acids in the lumen on the uptake of leucine from the vascular bed was measured using a fractional extraction technique; sucrose was the extracellular marker. There was complete correlation between the amino acids which promoted the extraction of leucine from the vascular bed and those which inhibited leucine wash-out into the vascular bed. 4. In contrast, the wash-out of leucine into the vascular bed was not accelerated by the addition of amino acids to the vascular perfusate, and the presence of 10 mM-leucine in the vascular bed had very little effect upon the mucosal-to-serosal flux of leucine. 5. These results are discussed with regard to the specificity of an exit system for leucine, in the intestinal epithelium, which appears to have an energy requirement. PMID:6975822

  12. Branched-chain amino acids complex inhibits melanogenesis in B16F0 melanoma cells.

    PubMed

    Cha, Jae-Young; Yang, Hyun-Ju; Moon, Hyung-In; Cho, Young-Su

    2012-04-01

    Present study was investigated the effect of each or complex of three branched-chain amino acids (BCAAs; isoleucine, leucine, and valine) on melanin production in B16F0 melanoma cells treated with various concentrations (1-16 mM) for 72 h. Among the 20 amino acids, lysine and glycine showed the highest activities of DPPH radical scavenging and mushroom tyrosinase inhibition, respectively. Each and combination of BCAAs reduced melanogenesis in a concentration-dependent manner without any morphological changes and cell viability in melanoma cells. Present study was also investigated the inhibitory effects of each or complex of BCAAs at each 10 mM concentration on the 100 μM IBMX-mediated stimulation of melanogenesis in melanoma cells for 72 h and found that IBMX treatment was stimulated to enhance melanin synthesis and that the complex of BCAAs was the most effectively inhibited in the melanin amounts of cellular and extracellular and the whitening the cell pellet. When the inhibitory effect of BCAAs on tyrosinase was examined by intracellular tyrosinase assay, both isoleucine and valine exhibit slightly inhibition, but leucine and combination of BCAAs did not inhibit the cell-derived tyrosinase activity. Present study demonstrated that complex of BCAAs inhibited melanin production without changes intercellular tyrosinase activity. Thus, the complex of BCAAs may be used in development of safe potentially depigmenting agents. PMID:21854182

  13. Evaluation of circulating levels and renal clearance of natural amino acids in patients with Cushing's disease.

    PubMed

    Faggiano, A; Pivonello, R; Melis, D; Alfieri, R; Filippella, M; Spagnuolo, G; Salvatore, F; Lombardi, G; Colao, A

    2002-02-01

    Although the hypercortisolism-induced impairment of protein homeostasis is object of several studies, a detailed evaluation of the complete amino acid profile of patients with Cushing's syndrome (CS) has never been performed. The aim of the current open transversal controlled study was to evaluate serum and urinary concentrations as well as renal clearance of the complete series of natural amino acids and their relationship with glucose tolerance in patients with Cushing's disease (CD). Twenty patients with CD (10 active and 10 cured) and 20 sex- and age-matched healthy controls entered the study. Measurement of serum and urinary levels of the complete series of natural amino acids was performed in all patients analyzed by cationic exchange high performance liquid cromatography (HPLC) after 2 weeks of a standardized protein intake regimen. The renal clearance (renal excretion rate) of each amino acid was calculated on the basis of the serum and urinary concentrations of creatinine and the specific amino acid. Fasting glucose and insulin levels, glucose and insulin response to standard glucose load, insulinogenic and homeostasis model insulin resistance (Homa-R) indexes were also evaluated and correlated to the circulating levels and renal clearances of each amino acid. Significantly higher serum (p<0.01) and urinary (p<0.05) levels of alanine and cystine, lower serum and higher urinary levels of leucine, isoleucine and valine (p<0.05) and higher renal excretion rates of leucine, isoleucine and valine (p<0.01) were found in patients with active CD than in patients cured from the disease and in controls. No difference was found between cured patients and controls. Creatinine clearance was similar in active and cured patients and in controls. In patients with active CD, urinary cortisol levels were significantly correlated to urinary cystine levels (r=0.85; p<0.01) and renal excretion rate of leucine (r=-0.76; p<0.05), isoleucine (r=-0.76; p<0.05) and valine (r=-0

  14. Leucine regulation of the ilvGEDA operon of Serratia marcescens by attenuation is modulated by a single leucine codon.

    PubMed Central

    Hsu, J H; Harms, E; Umbarger, H E

    1985-01-01

    The effect of leucine limitation and of restricted leucine tRNA charging on the expression of the ilvGEDA operon of Serratia marcescens was examined. In this organism, the ilv leader region specifies a putative peptide containing only a single leucine codon that could be involved in leucine-mediated control by attenuation (E. Harms, J.-H. Hsu, C. S. Subrahmanyam, and H. E. Umbarger, J. Bacteriol. 164:207-216, 1985). A plasmid (pPU134) containing the DNA of the S. marcescens ilv control region and three of the associated structural genes was studied as a single chromosomal copy in an Escherichia coli strain auxotrophic for all three branched-chain amino acids. The S. marcescens ilv genes responded to a multivalent control similar to that found in other enteric organisms. Furthermore, the S. marcescens ilv genes were derepressed when the charging of leucine tRNA was restricted in a leuS derivative of E. coli that had been transformed with pPU134. It was concluded that ribosome stalling leading to deattenuation is not dependent on either tandem or a consecutive series of codons for the regulatory amino acid. However, the fact that the single leucine codon is a less frequently used codon (CUA) may be important. The procedure for obtaining the cloned ilv genes in single chromosomal copy exploited the dependence of ColE1 replicons on the polA gene. The cloning experiments also revealed a branched-chain amino acid-glutamate transaminase in S. marcescens that is different from transaminase B. PMID:3900038

  15. Knockout of leucine aminopeptidase in Toxoplasma gondii using CRISPR/Cas9.

    PubMed

    Zheng, Jun; Jia, Honglin; Zheng, Yonghui

    2015-02-01

    Leucine aminopeptidases of the M17 peptidase family represent ideal drug targets for therapies directed against the pathogens Plasmodium, Babesia and Trypanosoma. Previously, we characterised Toxoplasma gondii leucine aminopeptidase and demonstrated its role in regulating the levels of free amino acids. In this study, we evaluated the potential of T. gondii leucine aminopeptidase as a drug target in T. gondii by a knockout method. Existing knockout methods for T. gondii have many drawbacks; therefore, we developed a new technique that takes advantage of the CRISPR/Cas9 system. We first chose a Cas9 target site in the gene encoding T. gondii leucine aminopeptidase and then constructed a knockout vector containing Cas9 and the single guide RNA. After transfection, single tachyzoites were cloned in 96-well plates by limiting dilution. Two transfected strains derived from a single clone were cultured in Vero cells, and then subjected to expression analysis by western blotting. The phenotypic analysis revealed that knockout of T. gondii leucine aminopeptidase resulted in inhibition of attachment/invasion and replication; both the growth and attachment/invasion capacity of knockout parasites were restored by complementation with a synonymously substituted allele of T. gondii leucine aminopeptidase. Mouse experiments demonstrated that T. gondii leucine aminopeptidase knockout somewhat reduced the pathogenicity of T. gondii. An enzymatic activity assay showed that T. gondii leucine aminopeptidase knockout reduced the processing of a leucine aminopeptidase-specific substrate in T. gondii. The absence of leucine aminopeptidase activity could be slightly compensated for in T. gondii. Overall, T. gondii leucine aminopeptidase knockout influenced the growth of T. gondii, but did not completely block parasite development, virulence or enzymatic activity. Therefore, we conclude that leucine aminopeptidase would be useful only as an adjunctive drug target in T. gondii. PMID

  16. Optical Properties of TGS Crystal with L-Valine Admixture

    SciTech Connect

    Stadnyk, V. Yo. Romanyuk, N. A.; Kiryk, Yu. I.

    2010-11-15

    The thermal expansion and temperature and the spectral dependences of the refractive indices and birefringence of triglycine sulphate (TGS) crystals with a 5% L-valine admixture have been investigated. It is established that the introduction of L-valine weakens the temperature dependence of the refractive indices and the birefringence and thermal expansion of TGS crystals. The parameters of the Sellmeier formula, refractions, and electronic polarizabilities are calculated. The changes observed may be related to the increase in hardness of admixture-containing crystals, the decrease in the spontaneous polarization, the replacement of the refraction components of the valine bond, or the spontaneous electro-optic effect.

  17. Optical Properties of TGS Crystal with L-Valine Admixture

    NASA Astrophysics Data System (ADS)

    Stadnyk, V. Yo.; Romanyuk, N. A.; Kiryk, Yu. I.

    2010-11-01

    The thermal expansion and temperature and the spectral dependences of the refractive indices and birefringence of triglycine sulphate (TGS) crystals with a 5% L-valine admixture have been investigated. It is established that the introduction of L-valine weakens the temperature dependence of the refractive indices and the birefringence and thermal expansion of TGS crystals. The parameters of the Sellmeier formula, refractions, and electronic polarizabilities are calculated. The changes observed may be related to the increase in hardness of admixture-containing crystals, the decrease in the spontaneous polarization, the replacement of the refraction components of the valine bond, or the spontaneous electro-optic effect.

  18. Interference by methionine on valine uptake in Acremonium chrysogenum.

    PubMed Central

    Alonso, M J; Luengo, J M

    1987-01-01

    The incorporation of L-[U-14C]valine into delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV), a direct biosynthetic precursor of penicillins and cephalosporins, was studied. When DL-methionine was added to Acremonium chrysogenum culture broths, no labeled ACV was found, while a large amount of radioactive ACV was detected when methionine was not present. DL-Norleucine, a nonsulfur analog of methionine, also inhibited the synthesis of radioactive ACV to some degree. This effect was due to the inhibition of valine transport by methionine and norleucine. PMID:3566258

  19. beta-hydroxyisobutyryl coenzyme A deacylase deficiency: a defect in valine metabolism associated with physical malformations

    SciTech Connect

    Brown, G.K.; Hunt, S.M.; Scholem, R.; Fowler, K.; Grimes, A.; Mercer, J.F.; Truscott, R.M.; Cotton, R.G.; Rogers, J.G.; Danks, D.M.

    1982-10-01

    An infant, born to parents who were first cousins had multiple physical malformations. An associated biochemical abnormality was suggested by the urinary excretion of cysteine and cysteamine conjugates of methacrylic acid. The coenzyme A (CoA) ester of this compound is an intermediate in the pathway of valine oxidation. Subsequent investigation revealed a deficiency of beta-hydroxyisobutyryl-CoA deacylase, an enzyme unique to valine metabolism. The enzyme defect results in accumulation of methacrylyl-CoA, a highly reactive compound, which readily undergoes addition reactions with free sulfhydryl groups. Tissue damage due to reactions between methacrylyl-CoA and important sulfhydryl-containing enzymes and cofactors may account for the teratogenic effects seen in this patient.

  20. Charged Amino Acid-rich Leucine Zipper-1 (Crlz-1) as a Target of Wnt Signaling Pathway Controls Pre-B Cell Proliferation by Affecting Runx/CBFβ-targeted VpreB and λ5 Genes.

    PubMed

    Choi, Seung-Young; Park, Sung-Kyun; Yoo, Han-Woong; Pi, Joo-Hyun; Kang, Chang-Joong

    2016-07-15

    The proliferation of pre-B cells is known to further increase the clonal diversity of B cells at the stage of pre-B cells by allowing the same rearranged heavy chains to combine with differently rearranged light chains in a subsequent developmental stage. Crlz-1 (charged amino acid-rich leucine zipper-1) was found to control this proliferation of pre-B cells by working as a Wnt (wingless-related mouse mammary tumor virus integration site) target gene in these cells. Mechanistically, Crlz-1 protein functioned by mobilizing cytoplasmic CBFβ (core binding factor β) into the nucleus to allow Runx (runt-related transcription factor)/CBFβ heterodimerization. Runx/CBFβ then turned on its target genes such as EBF (early B cell factor), VpreB, and λ5 and thereby pre-B cell receptor signaling, leading to the expression of cyclins D2 and D3 Actually, the proliferative function of Crlz-1 was demonstrated by not only Crlz-1 or β-catenin knockdown but also Crlz-1 overexpression. Furthermore, the mechanistic view that the proliferative function of Crlz-1 is caused by relaying Wnt/β-catenin to pre-B cell receptor signaling pathways through the regulation of Runx/CBFβ heterodimerization was also verified by employing niclosamide, XAV939, and LiCl as Wnt inhibitors and activator, respectively. PMID:27226553

  1. Dietary leucine requirement of juvenile Japanese seabass ( Lateolabrax japonicus)

    NASA Astrophysics Data System (ADS)

    Li, Yan; Cheng, Zhenyan; Mai, Kangsen; Ai, Qinghui

    2015-02-01

    A 56-day feeding trial was conducted to examine the dietary leucine requirement of juvenile Japanese seabass in seawater floating net cages (1.5 m × 1.5 m × 2.0 m). Six isonitrogenous (crude protein 40%) and isoenergetic (gross energy 20 kJ g-1) diets were formulated to contain different concentrations of leucine (0.9%, 1.49%, 2.07%, 2.70%, 3.30% and 3.88% of dry matter). Crystalline L-amino acids were supplemented to simulate the whole body amino acid pattern of Japanese seabass except for leucine. Three groups (30 fish individuals each, 8.0 g ± 0.20 g in initial weight) were fed to apparent satiation at 5:00 and 17:30 every day. During the experimental period, the water temperature ranged from 26 to 32δC and salinity from 26 to 30, and the dissolved oxygen was maintained at 7 mg L-1. The results showed that weight gain ( WG), nitrogen retention ( NR), feed efficiency ( FE) and protein efficiency ratio ( PER) were significantly increased when dietary leucine was increased from 0.90% to 2.70% of dry matter, and then declined. WG was the highest when fish were fed D4 containing 2.70% of leucine. No significant differences were observed in body composition among dietary treatments ( P > 0.05). Considering the change of WG, the optimum dietary leucine requirement of juvenile Japanese seabass was either 2.39% of dry matter or 5.68% of dietary protein.

  2. Phosphate depletion impairs leucine-induced insulin secretion.

    PubMed

    Oh, H Y; Fadda, G Z; Smogorzewski, M; Liou, H H; Massry, S G

    1994-11-01

    Phosphate depletion (PD) in vivo causes a sundry of abnormalities in pancreatic islets including a rise in cytosolic calcium, low ATP content, reduced Ca2+ ATPase and Na(+)-K+ ATPase activity, and impaired insulin secretion in response to glucose or potassium. L-Leucine is a strong secretagogue that triggers insulin secretion by deamination to alpha-ketoisocaproic acid (KIC) and the subsequent metabolism of the latter to ATP and by the activation of glutamate dehydrogenase (GLDH), which acts on glutamate to generate alpha-ketoglutarate, the metabolism of which results in ATP production. The generation of ATP triggers events that lead to insulin secretion. It is not known whether PD impairs leucine-induced insulin secretion, and the cellular derangements that are involved in such an abnormality are not defined. These issues were studied in PD rats and in pair-weighed normal animals as controls. D-Leucine uptake by islets from PD rats is normal, but both leucine- and KIC-induced insulin secretions are impaired and the activity of branched-chain keto acid dehydrogenase, which facilitates the metabolism of KIC, is reduced. Both leucine and 2-aminobicyclo (2-2-1) haptene failed to stimulate GLDH and to augment the generation of alpha-ketoglutarate in the islets of PD rats. Also, the concentration of basal alpha-ketoglutarate was significantly higher in the islets of PD rats, suggesting that its metabolism is impaired. In addition, the activity of glutaminase is significantly reduced, an abnormality that would result in decreased production of glutamate, the substrate for GLDH. The data show that PD impairs leucine-induced insulin secretion.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7873737

  3. Baicalein reverts L-valine-induced persistent sodium current up-modulation in primary cortical neurons.

    PubMed

    Caioli, Silvia; Candelotti, Elena; Pedersen, Jens Z; Saba, Luana; Antonini, Alessia; Incerpi, Sandra; Zona, Cristina

    2016-04-01

    L-valine is a branched-chain amino acid (BCAA) largely used as dietary integrator by athletes and involved in some inherited rare diseases such as maple syrup urine disease. This pathology is caused by an altered BCAA metabolism with the accumulation of toxic keto acids in tissues and body fluids with consequent severe neurological symptoms. In animal models of BCAA accumulation, increased oxidative stress levels and lipid peroxidation have been reported. The aim of this study was to analyze both whether high BCAA concentrations in neurons induce reactive oxygen species (ROS) production and whether, by performing electrophysiological recordings, the neuronal functional properties are modified. Our results demonstrate that in primary cortical cultures, a high dose of valine increases ROS production and provokes neuronal hyperexcitability because the action potential frequencies and the persistent sodium current amplitudes increase significantly compared to non-treated neurons. Since Baicalein, a flavone obtained from the Scutellaria root, has been shown to act as a strong antioxidant with neuroprotective effects, we evaluated its possible antioxidant activity in primary cortical neurons chronically exposed to L-valine. The preincubation of cortical neurons with Baicalein prevents the ROS production and is able to revert both the neuronal hyperexcitability and the increase of the persistent sodium current, indicating a direct correlation between the ROS production and the altered physiological parameters. In conclusion, our data show that the electrophysiological alterations of cortical neurons elicited by high valine concentration are due to the increase in ROS production, suggesting much caution in the intake of BCAA dietary integrators. PMID:26721313

  4. Synthesis, spectroscopic, mutagenic, and cytotoxicity studies of some mixed-ligand platinum(II) complexes of 2,2'-bipyridine and amino acids.

    PubMed

    Jain, N; Mital, R; Ray, K S; Srivastava, T S; Bhattacharya, R K

    1987-09-01

    Seven platinum(II) complexes of the type [Pt(bipy)(AA)]n+ (where n = 1 or 0 and AA is anion of L-valine, L-isoleucine, L-aspartic acid (dianion), L-glutamic acid (dianion), L-glutamine, L-proline, or S-methyl-L-cysteine) have been prepared and characterized. The modes of binding of amino acids in these complexes have been ascertained particularly by infrared and 1H NMR spectral studies. The L-glutamine complex shows a ID50 value (50% inhibitory dose) in the range of greater than 20 micrograms/ml to 100 micrograms/ml of the complex. However, the complexes of L-valine, L-isoleucine, L-aspartic acid, L-glutamic acid, L-proline, and S-methyl-L-cysteine show ID50 values greater than 100 micrograms/ml of the complex. The above complexes also show inferior growth inhibition of P-388 cells than platinum(II) complexes of 2,2'-bipyridine with L-alanine, L-leucine, L-methionine, and L-aspargine as reported earlier. The platinum(II) complexes of 2,2'-bipyridine with glycine (Gly), L-alanine (Ala), L-leucine (leu), L-valine (Val), L-methionine (Met), L-phenylalanine (Phe), L-serine (Ser), L-tyrosine (Tyr) and L-tryptophan (Trp) have been tested for mutagenesis using TA 100 and TA 98 strains. They show nonmutagenicity. This is in contrast to the cis-[Pt(NH3)2Cl2] showing a base pair substitution mutagenesis. PMID:3320273

  5. Alpha-keto and alpha-hydroxy branched-chain acid interrelationships in normal humans.

    PubMed

    Hoffer, L J; Taveroff, A; Robitaille, L; Mamer, O A; Reimer, M L

    1993-09-01

    Plasma concentrations of the branched-chain amino acids leucine, isoleucine and valine, and those of leucine's and isoleucine's transamination products alpha-ketoisocaproic acid (KICA) and alpha-keto-beta-methylvaleric acid (KMVA), respectively, are known to increase after a protein meal or during extended fasting, but little or no increase in the concentration of valine's transamination product, alpha-ketoisovaleric acid (KIVA), has been observed under these conditions. To determine whether this could be explained by the conversion of KIVA to its alpha-hydroxy analogue, we measured the plasma concentrations of KICA, KMVA and KIVA, as well as their alpha-hydroxy analogues [alpha-hydroxyisocaproic acid (HICA), alpha-hydroxy-beta-methylvaleric acid (HMVA) and alpha-hydroxyisovaleric acid (HIVA)], in normal volunteers immediately after a protein meal or during a 60-h fast. We also determined the oxidoreduction equilibrium constants for HIVA/KIVA and HICA/KICA and their extent of plasma protein binding. In subjects in the postabsorptive state, the plasma concentrations of KICA and KMVA were 100 times those of HICA and HMVA, whereas that of KIVA was only twice that of HIVA. Shortly after a protein meal, KICA and KMVA concentrations increased significantly by 30 and 60%, respectively, whereas that of KIVA decreased by 25% (P < 0.05). HICA, HMVA and HIVA concentrations did not change. During prolonged fasting the plasma concentrations of all six metabolites increased gradually. The high plasma keto/hydroxy acid ratios were not related to their K(eq), which favored alpha-hydroxy analogue formation. The reduction of the branched-chain alpha-keto acids to their alpha-hydroxy analogues seems to take place too slowly to attain thermodynamic equilibrium.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8360777

  6. Light-activated amino acid transport in Halobacterium halobium envelope vesicles

    NASA Technical Reports Server (NTRS)

    Macdonald, R. E.; Lanyi, J. K.

    1977-01-01

    Vesicles prepared from Halobacterium halobium cell envelopes accumulate amino acids in response to light-induced electrical and chemical gradients. Nineteen of 20 commonly occurring amino acids have been shown to be actively accumulated by these vesicles in response to illumination or in response to an artificially created Na+ gradient. On the basis of shared common carriers the transport systems can be divided into eight classes, each responsible for the transport of one or several amino acids: arginine, lysine, histidine; asparagine, glutamine; alanine, glycine, threonine, serine; leucine, valine, isoleucine, methionine; phenylalanine, tyrosine, tryptophan; aspartate; glutamate; proline. Available evidence suggests that these carriers are symmetrical in that amino acids can be transported equally well in both directions across the vesicle membranes. A tentative working model to account for these observations is presented.

  7. Extraction and carrier-facilitated transport of amino acids using synthetic non-cyclic receptors through bulk liquid membrane.

    PubMed

    Joshi, Pratibha; Joshi, Nidhi; Sharma, Uma

    2006-10-01

    The extraction and carrier-facilitated transport of amino acids (leucine, valine and glycine) was studied through chloroform bulk liquid membrane system using a series of non-cyclic receptors such as diethylene glycol (1), diethylene glycol dimethyl ether (2), diethylene glycol dibutyl ether (3), diethylene glycol dibenzoate (4), triethylene glycol (5) and tetraethylene glycol (6). The amount of amino acid extracted and transported depends mainly upon the structure and the concentration of the receptors and also on the concentration of amino acid. The receptors 1 to 4, having small chain length and flexible end groups, formed stable complexes with amino acids, and the flexibility of receptors in different conformational forms was responsible for their carrier ability, while the receptors 5 and 6, having larger chain length showed poor carrier ability. Hydrophobicity of amino acids also play an important role in the extraction as well as transport process. PMID:17133741

  8. Obesity-related elevations in plasma leucine are associated with alterations in enzymes involved in branched-chain amino acid metabolism.

    PubMed

    She, Pengxiang; Van Horn, Cynthia; Reid, Tanya; Hutson, Susan M; Cooney, Robert N; Lynch, Christopher J

    2007-12-01

    Elevations in branched-chain amino acids (BCAAs) in human obesity were first reported in the 1960s. Such reports are of interest because of the emerging role of BCAAs as potential regulators of satiety, leptin, glucose, cell signaling, adiposity, and body weight (mTOR and PKC). To explore loss of catabolic capacity as a potential contributor to the obesity-related rises in BCAAs, we assessed the first two enzymatic steps, catalyzed by mitochondrial branched chain amino acid aminotransferase (BCATm) or the branched chain alpha-keto acid dehydrogenase (BCKD E1alpha subunit) complex, in two rodent models of obesity (ob/ob mice and Zucker rats) and after surgical weight loss intervention in humans. Obese rodents exhibited hyperaminoacidemia including BCAAs. Whereas no obesity-related changes were observed in rodent skeletal muscle BCATm, pS293, or total BCKD E1alpha or BCKD kinase, in liver BCKD E1alpha was either unaltered or diminished by obesity, and pS293 (associated with the inactive state of BCKD) increased, along with BCKD kinase. In epididymal fat, obesity-related declines were observed in BCATm and BCKD E1alpha. Plasma BCAAs were diminished by an overnight fast coinciding with dissipation of the changes in adipose tissue but not in liver. BCAAs also were reduced by surgical weight loss intervention (Roux-en-Y gastric bypass) in human subjects studied longitudinally. These changes coincided with increased BCATm and BCKD E1alpha in omental and subcutaneous fat. Our results are consistent with the idea that tissue-specific alterations in BCAA metabolism, in liver and adipose tissue but not in muscle, may contribute to the rise in plasma BCAAs in obesity. PMID:17925455

  9. Chiral conducting surfaces via electrochemical oxidation of L-leucine-oligothiophenes.

    PubMed

    McTiernan, Christopher D; Omri, Karim; Chahma, M'hamed

    2010-09-17

    Polythiophenes bearing a specific chiral center such as L-leucine have been prepared via the electrochemical oxidation of a series of L-leucine functionalized oligothiophenes (monothiophenes and terthiophenes). These oligothiophenes have been prepared through the condensation of L-leucine methyl ester and the corresponding thiophene monomers in the presence of hydroxybenzotriazole (HOBt) and N,N'-dicyclohexylcarbodiimide (DCC) followed by hydrolysis of the esters. The electroactive polymers are electrochemically stable and exhibit excellent adhesive properties on electrode surfaces (platinum, gold, and glassy carbon) as well as interesting optical properties in both doped and undoped states. Hydrogen bonds between a free amino acid (L-leucine, D-leucine, L-alanine, D-alanine, and D/L-alanine) and the L-leucine based polythiophenes (chiral conducting surface) were probed using cyclic voltammetry. Preliminary results show that the capacitive current of a modified L-leucine-polythiophene electrode decreases as a result of the formation of a hydrogen bond barrier on the surface of the chiral conducting surface accompanied with a shift of the oxidation potential. Cyclic voltammetry responses resulting from the interaction of the chiral conducting surface with L and Dfree amino acid isomers are similar. The formation of hydrogen bonds between the chiral conducting surfaces and the free amino acids was characterized by (1)H NMR. A chemical shift was observed for the N-H group in monomer 6 as a result of the hydrogen bond formation between the L-leucine methyl ester (D-leucine methyl ester, D/L-leucine methyl ester) and monomer 6. PMID:20718451

  10. Compartmentalization of amino acids in surfactant aggregates - Partitioning between water and aqueous micellar sodium dodecanoate and between hexane and dodecylammonium propionate trapped water in hexane

    NASA Technical Reports Server (NTRS)

    Fendler, J. H.; Nome, F.; Nagyvary, J.

    1975-01-01

    The partitioning of amino acids (glycine, alanine, leucine, phenylalanine, histidine, aspartic acid, glutamic acid, lysine, isoleucine, threonine, serine, valine, proline, arginine) in aqueous and nonaqueous micellar systems was studied experimentally. Partitioning from neat hexane into dodecylammonium propionate trapped water in hexane was found to be dependent on both electrostatic and hydrophobic interactions, which implies that the interior of dodecylammonium propionate aggregates is negatively charged and is capable of hydrogen bonding in addition to providing a hydrophobic environment. Unitary free energies of transfer of amino acid side chains from hexane to water were determined and solubilities of amino acids in neat hexane substantiated the amino acid hydrophobicity scale. The relevance of the experiments to prebiotic chemistry was examined.

  11. Leucine in Obesity: Therapeutic Prospects.

    PubMed

    Yao, Kang; Duan, Yehui; Li, Fengna; Tan, Bie; Hou, Yongqing; Wu, Guoyao; Yin, Yulong

    2016-08-01

    Obesity develops from an imbalance of energy homeostasis and is associated with chronic low-grade inflammation in white adipose tissues (WAT). Inflammation is involved in the pathophysiology of many obesity-induced disorders including insulin resistance and diabetes. Increasing evidence has shown that dietary leucine supplementation positively affects the parameters associated with obesity and obesity-related metabolic disorders. The beneficial effects include increased loss of body weight, reduced WAT inflammation, improved lipid and glucose metabolism, enhanced mitochondrial function, and preserved lean body mass. Although these beneficial effects have not been clearly established, dietary leucine supplementation, either alone or as part of a therapeutic regimen, may be a good nutritional tool in the prevention and management of obesity and obesity-induced metabolic disorders. PMID:27256112

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

    PubMed

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

    2015-09-01

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

  13. flrB, a Regulatory Locus Controlling Branched-Chain Amino Acid Biosynthesis in Salmonella typhimurium

    PubMed Central

    Friedberg, Devorah; Mikulka, Thomas W.; Jones, Judith; Calvo, Joseph M.

    1974-01-01

    Salmonella typhimurium strain CV123 (ara-9 gal-205 flrB1), isolated as a mutant resistant to trifluoroleucine, has derepressed and constitutive levels of enzymes forming branched-chain amino acids. This strain grows more slowly than the parent at several temperatures, both in minimal medium and nutrient broth. It overproduces and excretes sizeable amounts of leucine, valine, and isoleucine in comparison with the parental strain. Both leuS (coding for leucyl-transfer ribonucleic acid [tRNA]synthetase) and flrB are linked to lip (min 20 to 25) by P1 transduction, whereas only leuS is linked to lip by P22 transduction. Strain CV123 containing an F′ lip+ episome from Escherichia coli has repressed levels of leucine-forming enzymes, indicating that flrB+ is dominant to flrB. Leucyl-tRNA synthetase from strain CV123 appears to be identical to the leucyl-tRNA synthetase in the parent. No differences were detected between strain CV123 and the parent with respect to tRNA acceptor activity for a number of amino acids. Furthermore, there was no large difference between the two strains in the patterns of leucine tRNA isoaccepting species after fractionation on several different columns. Several other flrB strains exhibited temperature-sensitive excretion of leucine, i.e., they excreted leucine at 37 C but not 25 C. In one such strain, excretion at 37 C was correlated with derepression of some enzymes specified by ilv and leu. These latter results suggest that flrB codes for a protein. PMID:4598011

  14. flrB, a regulatory locus controlling branched-chain amino acid biosynthesis in Salmonella typhimurium.

    PubMed

    Friedberg, D; Mikulka, T W; Jones, J; Calvo, J M

    1974-06-01

    Salmonella typhimurium strain CV123 (ara-9 gal-205 flrB1), isolated as a mutant resistant to trifluoroleucine, has derepressed and constitutive levels of enzymes forming branched-chain amino acids. This strain grows more slowly than the parent at several temperatures, both in minimal medium and nutrient broth. It overproduces and excretes sizeable amounts of leucine, valine, and isoleucine in comparison with the parental strain. Both leuS (coding for leucyl-transfer ribonucleic acid [tRNA]synthetase) and flrB are linked to lip (min 20 to 25) by P1 transduction, whereas only leuS is linked to lip by P22 transduction. Strain CV123 containing an F' lip(+) episome from Escherichia coli has repressed levels of leucine-forming enzymes, indicating that flrB(+) is dominant to flrB. Leucyl-tRNA synthetase from strain CV123 appears to be identical to the leucyl-tRNA synthetase in the parent. No differences were detected between strain CV123 and the parent with respect to tRNA acceptor activity for a number of amino acids. Furthermore, there was no large difference between the two strains in the patterns of leucine tRNA isoaccepting species after fractionation on several different columns. Several other flrB strains exhibited temperature-sensitive excretion of leucine, i.e., they excreted leucine at 37 C but not 25 C. In one such strain, excretion at 37 C was correlated with derepression of some enzymes specified by ilv and leu. These latter results suggest that flrB codes for a protein. PMID:4598011

  15. Differential transport properties of D-leucine and L-leucine in the archaeon, Halobacterium salinarum.

    PubMed

    Tanaka, M; Mukohata, Y; Yuasa, S

    2000-04-01

    The transport of D-leucine was compared with that of L-leucine in Halobacterium salinarum. When a high-outside/low-inside Na+ gradient was imposed, D-leucine as well as L-leucine accumulated in envelope vesicles, supporting the hypothesis that D-leucine is transported via a symport system along with Na+. Kinetic analyses, including inhibition experiments, indicated that both enantiomers are transported via a common carrier. However, a Hill plot indicated a single binding site for Na+ during L-leucine transport, but dual binding sites for Na+ during D-leucine transport. Furthermore, D-leucine transport was dependent on electrical membrane potential, suggesting that a transporter bound with D-leucine is positively charged. L-leucine transport was slightly, if at all, dependent on membrane potential, suggesting that a transporter bound with L-leucine is electrically neutral. These results indicate that the leucine carrier in Halobacterium salinarum translocates two moles of Na+ per mole of D-leucine, and one mole of Na+ per mole of L-leucine. PMID:10779875

  16. Chiral analysis of amino acids using electrochemical composite bienzyme biosensors.

    PubMed

    Domínguez, R; Serra, B; Reviejo, A J; Pingarrón, J M

    2001-11-15

    The construction and performance of bienzyme amperometric composite biosensors for the selective determination of l- or d-amino acids is reported. D- or L-Amino acid oxidase, horseradish peroxidase, and the mediator ferrocene were coimmobilized by simple physical inclusion into the bulk of a graphite-70% Teflon electrode matrix. Working conditions including amino acid oxidase loading and pH were optimized. Studies on the repeatability of the amperometric response obtained at +0.00 V, with and without regeneration of the electrode surface by polishing, on the useful lifetime of one single biosensor and on the reproducibility in the fabrication of different biosensors illustrate the robustness of the bioelectrodes design. Calibration plots by both amperometry in stirred solutions and flow injection with amperometric detection were obtained for L-arginine, L-phenylalanine, L-leucine, L-methionine, L-tryptophan, D-leucine, D-methionine, D-serine, and D-valine. Differences in sensitivity were discussed in terms of the hydrophobicity of the substrate and of the electrode surface. The bienzyme composite electrode was applied to the determination of L- and D-amino acids in racemic samples, as well as to the estimation of the L-amino acids content in muscatel grapes. PMID:11700983

  17. Leucine kinetics from (2H3)- and ( sup 13 C)leucine infused simultaneously by gut and vein

    SciTech Connect

    Hoerr, R.A.; Matthews, D.E.; Bier, D.M.; Young, V.R. )

    1991-01-01

    In amino acid tracer kinetic studies of the fed state, ingested amino acid may be taken up during its initial transit through splanchnic tissues and thus not enter the plasma compartment where tracer is infused. To investigate this possibility, adult human subjects received simultaneous intravenous (iv) and intragastric (ig) leucine tracer infusions, first during a postabsorptive (PA) 4-h primed continuous ig infusion of L-(1-13C)-leucine and L-(5,5,5-2H3)leucine iv, followed on a separate day by a fed infusion, in which an ig infusion of a liquid formula was started 2 h before the tracer infusion and continued throughout the tracer study. Subjects were accustomed to a constant experimental diet supplying 1.5 g protein.kg-1.day-1 and 41-45 kcal.kg-1.day-1 for 7 and 12 days before the PA and fed studies, respectively. For the PA study, plasma enrichment for the ig tracer was 3.34 +/- 0.27 (SE) mol + excess and for the iv tracer it was 4.18 +/- 0.10 (P less than 0.02). Enrichments of alpha-keto-isocaproic acid (KIC) were 3.24 +/- 0.16 (ig) and 3.02 +/- 0.14 (iv), respectively (not significant (NS)). For the fed study, plasma leucine enrichment for the ig tracer was 2.15 +/- 0.14 and for the iv tracer was 2.84 +/- 0.09 (P less than 0.02). KIC enrichments were 2.02 +/- 0.08 (ig) and 2.24 +/- 0.08 (iv), respectively (NS). In the PA study, the ratio of the plasma leucine enrichments for the ig and iv tracers was 0.80 +/- 0.06 and in the fed experiment, 0.76 +/- 0.05, respectively.

  18. Transport of amino acids in Lactobacillus casei by proton-motive-force-dependent and non-proton-motive-force-dependent mechanisms.

    PubMed

    Strobel, H J; Russell, J B; Driessen, A J; Konings, W N

    1989-01-01

    Lactobacillus casei 393 cells which were energized with glucose (pH 6.0) took up glutamine, asparagine, glutamate, aspartate, leucine, and phenylalanine. Little or no uptake of several essential amino acids (valine, isoleucine, arginine, cysteine, tyrosine, and tryptophan) was observed. Inhibition studies indicated that there were at least five amino acid carriers, for glutamine, asparagine, glutamate/aspartate, phenylalanine, or branched-chain amino acids. Transport activities had pH optima between 5.5 and 6.0, but all amino acid carriers showed significant activity even at pH 4.0. Leucine and phenylalanine transport decreased markedly when the pH was increased to 7.5. Inhibitors which decreased proton motive force (delta p) nearly eliminated leucine and phenylalanine uptake, and studies with de-energized cells and membrane vesicles showed that an artificial electrical potential (delta psi) of at least -100 mV was needed for rapid uptake. An artificial delta p was unable to drive glutamine, asparagine, or glutamate uptake, and transport of these amino acids was sensitive to a decline in intracellular pH. When intracellular pH was greater than 7.7, glutamine, asparagine, or glutamate was transported rapidly even though the proton motive force had been abolished by inhibitors. PMID:2492498

  19. Time-Resolved Transcriptome Analysis of Bacillus subtilis Responding to Valine, Glutamate, and Glutamine

    PubMed Central

    Ye, Bang-Ce; Zhang, Yan; Yu, Hui; Yu, Wen-Bang; Liu, Bao-Hong; Yin, Bin-Cheng; Yin, Chun-Yun; Li, Yuan-Yuan; Chu, Ju; Zhang, Si-Liang

    2009-01-01

    Microorganisms can restructure their transcriptional output to adapt to environmental conditions by sensing endogenous metabolite pools. In this paper, an Agilent customized microarray representing 4,106 genes was used to study temporal transcript profiles of Bacillus subtilis in response to valine, glutamate and glutamine pulses over 24 h. A total of 673, 835, and 1135 amino-acid-regulated genes were identified having significantly changed expression at one or more time points in response to valine, glutamate, and glutamine, respectively, including genes involved in cell wall, cellular import, metabolism of amino-acids and nucleotides, transcriptional regulation, flagellar motility, chemotaxis, phage proteins, sporulation, and many genes of unknown function. Different amino acid treatments were compared in terms of both the global temporal profiles and the 5-minute quick regulations, and between-experiment differential genes were identified. The highlighted genes were analyzed based on diverse sources of gene functions using a variety of computational tools, including T-profiler analysis, and hierarchical clustering. The results revealed the common and distinct modes of action of these three amino acids, and should help to elucidate the specific signaling mechanism of each amino acid as an effector. PMID:19763274

  20. Amino acids interference on the quantification of reducing sugars by the 3,5-dinitrosalicylic acid assay mislead carbohydrase activity measurements.

    PubMed

    Teixeira, Ricardo Sposina Sobral; da Silva, Ayla Sant'Ana; Ferreira-Leitão, Viridiana Santana; da Silva Bon, Elba Pinto

    2012-12-01

    This study evaluated the interference of the amino acids tryptophan, cysteine, histidine, tyrosine, hydroxyproline, leucine, proline, serine, glycine, valine, glutamic acid, phenylalanine, and methionine on the measurement of reducing sugars using a phenol-free 3,5-dinitrosalicylic acid (DNS) reagent. It was found that in reaction mixtures containing 20mM of either tryptophan, cysteine, histidine, tyrosine, or hydroxyproline the measurement of 3.7 mM glucose was overestimated by 76%, 50%, 35%, 18%, and 10%, respectively. The amino acids valine, glutamic acid, and phenylalanine did not affect the DNS reaction, while methionine decreased the color development by 5%. The measurement of glucose, xylose, arabinose, and cellobiose at the 3.7-12.4 mM range in the presence of 20 mM cysteine resulted in an overestimated concentration of 34.8-50%. Enzymatic assays for measuring xylanolytic and filter paper activity (FPAse) were conducted in the presence of 20-60 mM cysteine, and compared to cysteine-free assays. In the presence of cysteine, the measured xylanase activity increased threefold and the FPAse activity increased twofold due to the overestimation of the reducing sugar concentrations in the assays. The interference from cysteine was reduced to a maximum of 8.6% when a DNS reagent containing phenol was used. PMID:23103512

  1. The development and amino acid binding ability of nano-materials based on azo derivatives: theory and experiment.

    PubMed

    Shang, Xuefang; Du, Jinge; Yang, Wancai; Liu, Yun; Fu, Zhiyuan; Wei, Xiaofang; Yan, Ruifang; Yao, Ningcong; Guo, Yaping; Zhang, Jinlian; Xu, Xiufang

    2014-05-01

    Two nano-material-containing azo groups have been designed and developed, and the binding ability of nano-materials with various amino acids has been characterized by UV-vis and fluorescence titrations. Results indicated that two nano-materials showed the strongest binding ability for homocysteine among twenty normal kinds of amino acids (alanine, valine, leucine, isoleucine, methionine, aspartic acid, glutamic acid, arginine, glycine, serine, threonine, asparagine, phenylalanine, histidine, tryptophan, proline, lysine, glutamine, tyrosine and homocysteine). The reason for the high sensitivity for homocysteine was that two nano-materials containing an aldehyde group reacted with SH in homocysteine and afforded very stable thiazolidine derivatives. Theoretical investigation further illustrated the possible binding mode in host-guest interaction and the roles of molecular frontier orbitals in molecular interplay. Thus, the two nano-materials can be used as optical sensors for the detection of homocysteine. PMID:24656358

  2. Application of environmental forensics to identify the sources of ground water contamination using amino acid "finger print"

    NASA Astrophysics Data System (ADS)

    Choi, J.; Kim, J.; Park, J.; Nam, Y.; Lee, J.; Yoo, E.; Kim, H.; Lee, W.; Choe, S.; Han, J.

    2011-12-01

    The analysis of patterns of amino acids of the leachate from livestock burial site and the wastewater from the manure treatment plant was performed to trace the source of NO3-N contamination in groundwater near mass burial sites. Amino acid was analyzed with LC-MSMS using ODS-II column after the derivatiztion with PITC (phenylisothiocyanate) by following Edman Method. The average concentration of amino acid in the burial leachate was 531.90 mg/L and livestock wastewater was 1.75 mg/L. The concentration of burial leachate is about 300 times higher than that of livestock wastewater. The order of the concentration of each amino acid which were commonly detected in leachate was Valin > Leucine > Isoleucin. On the other hands, livestock wastewater showed different trend (Alanine > Lysine > Valine). Six amino acids among 20 amino acids which were stably detected in leachate and livestock wastewater were selected and compared with peak pattern. By determining the relative ratio of concentrations of amino acids (Ile/Val, Leu/Trp, Val/Trp, Lys/Leu, Lys/Ile, Met/Lys) in the same sample, the sources of the contamination was concluded. Based on this analysis using those indicators, samples affected by livestock wastewater were 43.0% (324 samples) and samples influenced by fertilizer or compost were 57.0% (470 samples) among 754 samples. Any sample among 754 samples didn't seem to be effected by leachate of nearby burial site.

  3. Regulation of Leucine Biosynthesis in Bacillus subtilis

    PubMed Central

    Ward, Jonathan B.; Zahler, Stanley A.

    1973-01-01

    The biosynthesis of α-isopropylmalate (αIPM) synthetase, IPM isomerase, and βIPM dehydrogenase in Bacillus subtilis can be derepressed in leucine auxotrophs by limiting them for leucine. The derepression of the three enzymes is apparently coordinate. A class of mutants resistant to 4-azaleucine excretes leucine and has derepressed levels of all three enzymes. The azaleucine-resistance mutations may lie in a gene (azlA) encoding a repressor. Efforts to find mutations characteristic of a constitutive operator have been unsuccessful. No polar mutations have been found among nine leucine auxotrophs that have characteristics of frameshift mutations. The enzyme catalyzing the first step in leucine biosynthesis, αIPM synthetase, is sensitive to feedback inhibition by leucine. We conclude that leucine biosynthesis is controlled by the inhibition of the activity of the first biosynthetic enzyme by leucine, and by the repression of the synthesis of the first three biosynthetic enzymes by leucine. The repression of the three enzymes may be under the control of a single repressor and a single operator, or of a single repressor and a separate operator for each structural gene. PMID:4200854

  4. Pyrolysis of simple amino acids and nucleobases: survivability limits and implications for extraterrestrial delivery

    NASA Astrophysics Data System (ADS)

    Basiuk, V. A.; Douda, J.

    1999-04-01

    The idea of extraterrestrial delivery of organic matter to the early Earth is strongly supported by the detection of a large variety of organic compounds in the interstellar medium, comets, and carbonaceous chondrites. Whether organic compounds essential for the emergence and evolution of life, particularly amino acids and nucleic acid bases found in the meteorites, can be efficiently delivered by other space bodies is unclear and depends primarily on capability of the biomolecules to survive high temperatures during atmospheric deceleration and impacts to the terrestrial surface. In the present study we estimated survivability of simple amino acids (glycine, Lalanine, α-aminoisobutyric acid, L-valine and L-leucine), purines (adenine and guanine) and pyrimidines (uracil and cytosine) under rapid heating to temperatures of 400-1000°C under N2 or CO2 atmosphere. We have found that most of the compounds studied cannot survive the temperatures substantially higher than 700°C however at 500600°C, the recovery can be at a percent level (or even 10%-level for adenine, uracil, alanine, and valine). The final fate of amino acids and nucleobases during the atmospheric deceleration and surface impacts is discussed depending on such factors as size of the space body, nature and altitude of the heating, chemical composition of the space body and of the atmosphere.

  5. Transfer coefficients for L-valine and the rate of incorporation of L-(1-/sup 14/C) valine into proteins in normal adult rat brain

    SciTech Connect

    Kirikae, M.; Diksic, M.; Yamamoto, Y.L.

    1988-08-01

    An autoradiographic method for the measurement of the rate of valine incorporation into brain proteins is described. The transfer coefficients for valine into and out of the brain and the rate of valine incorporation into normal rat brain proteins are given. The valine incorporation and the transfer constants of valine between different biological compartments are provided for 14 gray matter and 2 white matter structures of an adult rat brain. The rate of valine incorporation varies between 0.52 +/- 0.19 nmol/g/min in white matter and 1.94 +/- 0.47 in inferior colliculus (gray matter). Generally, the rate of valine incorporation is about three to four times higher in the gray matter than in the white matter structures.

  6. Leucine supplementation via drinking water reduces atherosclerotic lesions in apoE null mice

    PubMed Central

    Zhao, Yang; Dai, Xiao-yan; Zhou, Zhou; Zhao, Ge-xin; Wang, Xian; Xu, Ming-jiang

    2016-01-01

    Aim: Recent evidence suggests that the essential amino acid leucine may be involved in systemic cholesterol metabolism. In this study, we investigated the effects of leucine supplementation on the development of atherosclerosis in apoE null mice. Methods: ApoE null mice were fed with chow supplemented with leucine (1.5% w/v) in drinking water for 8 week. Aortic atherosclerotic lesions were examined using Oil Red O staining. Plasma lipoprotein-cholesterol levels were measured with fast protein liquid chromatography. Hepatic gene expression was detected using real-time PCR and Western blot analyses. Results: Leucine supplementation resulted in 57.6% reduction of aortic atherosclerotic lesion area in apoE null mice, accompanied by 41.2% decrease of serum LDL-C levels and 40.2% increase of serum HDL-C levels. The body weight, food intake and blood glucose level were not affected by leucine supplementation. Furthermore, leucine supplementation increased the expression of Abcg5 and Abcg8 (that were involved in hepatic cholesterol efflux) by 1.28- and 0.86-fold, respectively, and significantly increased their protein levels. Leucine supplementation also increased the expression of Srebf1, Scd1 and Pgc1b (that were involved in hepatic triglyceride metabolism) by 3.73-, 1.35- and 1.71-fold, respectively. Consequently, leucine supplementation resulted in 51.77% reduction of liver cholesterol content and 2.2-fold increase of liver triglyceride content. Additionally, leucine supplementation did not affect the serum levels of IL-6, IFN-γ, TNF-α, IL-10 and IL-12, but markedly decreased the serum level of MCP-1. Conclusion: Leucine supplementation effectively attenuates atherosclerosis in apoE null mice by improving the plasma lipid profile and reducing systemic inflammation. PMID:26687933

  7. Leucine stimulates protein synthesis in skeletal muscle of neonatal pigs by enhancing mTORC1 activation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Skeletal muscle in the neonate grows at a rapid rate due in part to an enhanced sensitivity to the postprandial rise in amino acids, particularly leucine. To elucidate the molecular mechanism by which leucine stimulates protein synthesis in neonatal muscle, overnight-fasted 7-day-old piglets were tr...

  8. Involvement of protein kinase C activation in L-leucine-induced stimulation of protein synthesis in l6 myotubes.

    PubMed

    Yagasaki, Kazumi; Morisaki, Naoko; Kitahara, Yoshiro; Miura, Atsuhito; Funabiki, Ryuhei

    2003-11-01

    Effects of leucine and related compounds on protein synthesis were studied in L6 myotubes. The incorporation of [(3)H]tyrosine into cellular protein was measured as an index of protein synthesis. In leucine-depleted L6 myotubes, leucine and its keto acid, alpha-ketoisocaproic acid (KIC), stimulated protein synthesis, while D-leucine did not. Mepacrine, an inhibitor of both phospholipases A(2) and C, canceled stimulatory actions of L-leucine and KIC on protein synthesis. Neither indomethacin, an inhibitor of cyclooxygenase, nor caffeic acid, an inhibitor of lipoxygenase, diminished their stimulatory actions, suggesting no involvement of arachidonic acid metabolism. Conversely, 1-O-hexadecyl-2-O-methylglycerol, an inhibitor of proteinkinase C, significantly canceled the stimulatory actions of L-leucine and KIC on protein synthesis, suggesting an involvement of phosphatidylinositol degradation and activation of protein kinase C. L-Leucine caused a rapid activation of protein kinase C in both cytosol and membrane fractions of the cells. These results strongly suggest that both L-leucine and KIC stimulate protein synthesis in L6 myotubes through activation of phospholipase C and protein kinase C. PMID:19003213

  9. Design and characterization of short antimicrobial peptides using leucine zipper templates with selectivity towards microorganisms.

    PubMed

    Ahmad, Aqeel; Azmi, Sarfuddin; Srivastava, Saurabh; Kumar, Amit; Tripathi, Jitendra Kumar; Mishra, Nripendra N; Shukla, Praveen K; Ghosh, Jimut Kanti

    2014-11-01

    Design of antimicrobial peptides with selective activity towards microorganisms is an important step towards the development of new antimicrobial agents. Leucine zipper sequence has been implicated in cytotoxic activity of naturally occurring antimicrobial peptides; moreover, this motif has been utilized for the design of novel antimicrobial peptides with modulated cytotoxicity. To understand further the impact of substitution of amino acids at 'a' and/or 'd' position of a leucine zipper sequence of an antimicrobial peptides on its antimicrobial and cytotoxic properties four short peptides (14-residue) were designed on the basis of a leucine zipper sequence without or with replacement of leucine residues in its 'a' and 'd' positions with D-leucine or alanine or proline residue. The original short leucine zipper peptide (SLZP) and its D-leucine substituted analog, DLSA showed comparable activity against the tested Gram-positive and negative bacteria and the fungal strains. The alanine substituted analog (ASA) though showed appreciable activity against the tested bacteria, it showed to some extent lower activity against the tested fungi. However, the proline substituted analog (PSA) showed lower activity against the tested bacterial or fungal strains. Interestingly, DLSA, ASA and PSA showed significantly lower cytotoxicity than SLZP against both human red blood cells (hRBCs) and murine 3T3 cells. Cytotoxic and bactericidal properties of these peptides matched with peptide-induced damage/permeabilization of mammalian cells and bacteria or their mimetic lipid vesicles suggesting cell membrane could be the target of these peptides. As evidenced by tryptophan fluorescence and acrylamide quenching studies the peptides showed similarities either in interaction or in their localization within the bacterial membrane mimetic negatively charged lipid vesicles. Only SLZP showed localization inside the mammalian membrane mimetic zwitterionic lipid vesicles. The results show

  10. Molecular aggregation in crystalline 1:1 complexes of hydrophobic D- and L-amino acids. I. The L-isoleucine series.

    PubMed

    Dalhus; Görbitz

    1999-06-01

    The amino acid L-isoleucine has been cocrystallized with seven selected D-amino acids including D-methionine [L-isoleucine-D-methionine (1/1), C(6)H(13)NO(2).C(5)H(11)NO(2)S, amino-acid side chain R = -CH(2)-CH(2)-S-CH(3)] and a homologous series from D-alanine [L-isoleucine-D-alanine (1/1), C(6)H(13)NO(2).C(3)H(7)NO(2), R = -CH(3)] through D-alpha-aminobutyric acid [L-isoleucine-D-alpha-aminobutyric acid (1/1), C(6)H(13)NO(2).C(4)H(9)NO(2), R = -CH(2)-CH(3)] and D-norvaline [L-isoleucine-D-norvaline (1/1), C(6)H(13)NO(2).C(5)H(11)NO(2), R = -CH(2)-CH(2)-CH(3)] to D-norleucine [L-isoleucine-D-norleucine (1/1), C(6)H(13)NO(2).C(6)H(13)NO(2), R = -CH(2)-CH(2)-CH(2)-CH(3)] with linear side chains, and D-valine [L-isoleucine-D-valine (1/1), C(6)H(13)NO(2).C(5)H(11)NO(2), R = -CH-(CH(3))(2)] and D-leucine [L-isoleucine-D-leucine (1/1), C(6)H(13)NO(2).C(6)H(13)NO(2), R = -CH(2)-CH-(CH(3))(2)] with branched side chains. All the crystal structures are divided into distinct hydrophilic and hydrophobic layers. In the five complexes with amino acids with linear side chains the polar parts of the D- and L-amino acids are related by pseudo-glide-plane symmetry, and four of them have remarkably similar molecular arrangements. The D-valine and D-leucine complexes, on the other hand, are structurally quite different with the polar parts of the D- and L-amino acids related by pseudo-inversion. Differences in the hydrogen-bond pattern in the two molecular arrangements are discussed. PMID:10927385

  11. Effective atomic numbers and electron densities of bacteriorhodopsin and its comprising amino acids in the energy range 1 keV-100 GeV

    NASA Astrophysics Data System (ADS)

    Ahmadi, Morteza; Lunscher, Nolan; Yeow, John T. W.

    2013-04-01

    Recently, there has been an interest in fabrication of X-ray sensors based on bacteriorhodopsin, a proton pump protein in cell membrane of Halobacterium salinarium. Therefore, a better understanding of interaction of X-ray photons with bacteriorhodopsin is required. We use WinXCom program to calculate the mass attenuation coefficient of bacteriorhodopsin and its comprising amino acids for photon energies from 1 keV to 100 GeV. These amino acids include alanine, arginine, asparagine, aspartic acid, glutamine, glutamic acid, glycine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, Asx1, Asx2, Glx1 and Glx2. We then use that data to calculate effective atomic number and electron densities for the same range of energy. We also emphasize on two ranges of energies (10-200 keV and 1-20 MeV) in which X-ray imaging and radiotherapy machines work.

  12. [Characteristics of the effect of gamma-irradiation on the amino acid composition of collagen as modified by a gaseous atmosphere].

    PubMed

    Duzhenkova, N A; Savich, A V

    1986-01-01

    The comparative changes in the amino acid composition of calf skin collagen after gamma-irradiation (doses from 100 to 1,000 Gy) in aqueous solutions under different gas atmospheres (O2, N2O, H2, vacuum) were investigated. The radiochemical yields of collagen amino acid residues destruction were determined. Under O2 (OH X, O2-) most of amino acids are destroyed with higher yields than under N2O. Leucine, valine, isoleucine, phenylalanine, arginine were the exception because of their high reaction rate constants with OH X and hydroxylation reactions. Under H2 (e-aq, H) and in vacuum (e-aq, OH X) the mechanism of collagen radiolysis changed due to its aggregation; the destruction of those amino acids which have high reaction rate constants with water radiolysis products was mainly observed (phenylalanine, tyrosine, histidine). PMID:3774972

  13. Leucine metabolism in patients with Hepatic Encephalopathy

    SciTech Connect

    McGhee, A.S.; Kassouny, M.E.; Matthews, D.E.; Millikan, W.

    1986-03-01

    A primed continuous infusion of (/sup 15/N, 1-/sup 13/C)leucine was used to determine whether increased oxidation and/or protein synthesis of leucine occurs in patients with cirrhosis. Five controls and patients were equilibrated on a metabolic balance diet (0.6 g protein per kg ideal body weight (IBW)). An additional four patients were equilibrated in the same manner with the same type of diet with a protein level of 0.75 g per kg IBW. Plasma leucine and breath CO/sub 2/ enrichments were measured by mass spectrometry. Protein synthesis and leucine metabolism were identical in controls and patients when both were fed a diet with 0.6 g protein/kg IBW. Results indicate that systemic derangements of leucine metabolism are not the cause of Hepatic Encephalopathy.

  14. Purification and identification of a novel leucine aminopeptidase from Bacillus thuringiensis israelensis.

    PubMed

    Cahan, Rivka; Hetzroni, Efrat; Nisnevitch, Marina; Nitzan, Yeshayahu

    2007-11-01

    A novel leucine aminopeptidase was purified from a Bacillus thuringiensis israelensis (Bti) culture. The purification stages included heating the concentrated supernatant to 65 degrees C for 90 min, anion-exchange chromatography by DEAE cellulose, and hydrophobic chromatography by phenyl Sepharose. The specific activity of leucine aminopeptidase after the hydrophobic chromatography increased by 215.5-fold and the yield was 16%. The molecular weight of the active enzyme was 59 kDa. Mass spectrometry analysis of the 59-kDa leucine aminopeptidase revealed that this protein has at least 41% homology with the cytosol leucine aminopeptidase produced by Bacillus cereus. Maximal leucine aminopeptidase activity occurred at 65 degrees C, pH 10 toward leucine as the amino acid terminus. The enzyme was strongly inhibited by bestatin, dithiothreitol, and 1,10-phenanthroline, indicating that the enzyme might be considered as a metallo-aminopeptidase that has disulfide bonds at the catalytic site or at a region that influences its configuration. Examination of the purified leucine aminopeptidase's effect on the activation of the protoxin Cyt1Aa from Bti revealed that when it acts synergistically with Bti endogenous proteases, it has only a minor role in the processing of Cyt1Aa into an active toxin. PMID:17682820

  15. Analysis of cyclic pyrolysis products formed from amino acid monomer.

    PubMed

    Choi, Sung-Seen; Ko, Ji-Eun

    2011-11-18

    Amino acid was mixed with silica and tetramethylammonium hydroxide (TMAH) to favor pyrolysis of amino acid monomer. The pyrolysis products formed from amino acid monomer were using GC/MS and GC. 20 amino acids of alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine were analyzed. The pyrolysis products were divided into cyclic and non-cyclic products. Among the 20 amino acids, arginine, asparagine, glutamic acid, glutamine, histidine, lysine, and phenylalanine generated cyclic pyrolysis products of the monomer. New cyclic pyrolysis products were formed by isolation of amino acid monomers. They commonly had polar side functional groups to 5-, 6-, or 7-membered ring structure. Arginine, asparagine, glutamic acid, glutamine, histidine, and phenylalanine generated only 5- or 6-membered ring products. However, lysine generated both 6- and 7-membered ring compounds. Variations of the relative intensities of the cyclic pyrolysis products with the pyrolysis temperature and amino acid concentration were also investigated. PMID:21993510

  16. Role of Insulin in the Regulation of Leucine Kinetics in the Conscious Dog

    PubMed Central

    Abumrad, Naji N.; Jefferson, L. S.; Rannels, S. R.; Williams, P. E.; Cherrington, A. D.; Lacy, W. W.

    1982-01-01

    To study the effect of insulin on leucine kinetics, three groups of conscious dogs were studied after an overnight fast (16-18 h). One, saline-infused group (n = 5), served as control. The other two groups were infused with somatostatin and constant replacement amount of glucagon; one group (n = 6) received no insulin replacement, to produce acute insulin deficiency, and the other (n = 6) was constantly replaced with 600 μU/kg per min insulin, to produce twice basal hyperinsulinemia. Hepatic and extrahepatic splanchnic (gut) balance of leucine and α-ketoisocaproate (KIC) were calculated using the arteriovenous difference technique. l,4,5,[3H]Leucine was used to measure the rates (micromoles per kilogram per minute) of appearance (Ra) and disappearance (Rd), and clearance (Cl) of plasma leucine (milliliters per kilogram per minute). Saline infusion for 7 h resulted in isotopic steady state, where Ra and Rd were equal (3.2±0.2 μmol/kg per min). Acute insulin withdrawal of 4-h duration caused the plasma leucine to increase by 40% (P < 0.005). This change was caused by a decrease in the outflow of leucine (Cl) from the plasma, since Ra did not change. The net hepatic release of the amino acid (0.24±0.03 μmol/kg per min) did not change significantly; the arterio-deep femoral venous differences of leucine (−10±1 μmol/liter) and KIC (−12±2 μmol/liter) did not change significantly indicating net release of the amino and ketoacids across the hindlimb. Selective twice basal hyperinsulinemia resulted in a 36% drop in plasma leucine (from control levels of 128±8 to 82±7 μmol/liter, P < 0.005) within 4 h. This was accompanied by a 15% reduction in Ra and a 56% rise in clearance (P < 0.001, both). Net hepatic leucine production and net release of leucine and KIC across the hindlimb fell markedly. These studies indicate that physiologic changes in circulating insulin levels result in a differential dose-dependent effect on total body leucine metabolism in the

  17. Substrate specificity of duckling hepatic and renal D-amino acid oxidase.

    PubMed

    Elkin, R G; Lyons, M L

    1988-05-01

    The substrate specificity of duckling hepatic and renal D-amino acid oxidase (DAAO; D-amino acid: O2 oxidoreductase [deaminating], E.C. 1.4.3.3) was determined using a method based on the combination of coupled enzyme reactions and a colorimetric procedure. When activities were averaged across tissues, D-proline was the most reactive substrate, followed by (in order) D-phenylalanine, D-alanine, D-methionine, D-leucine, D-isoleucine, D-valine, D-tryptophan, D-arginine, and D-lysine. Compared with D-alanine, duckling DAAO had minimal or no reactivity with D-asparagine, D-glutamine, D-histidine, D-threonine, D-cysteine, glycine, or D-serine. These results were in general agreement with data from other vertebrate species. PMID:2900508

  18. Effect of amino acids on insulin-stimulated glucose metabolism in fat cells.

    PubMed

    Mizunuma, T; Takahashi, Y; Okuda, H

    1981-02-01

    The effect of amino acids on insulin responsiveness in epididymal adipose tissue was examined. It was found that insulin-stimulated glucose oxidation in fat cells was significantly inhibited by glycine, alanine, valine, leucine, isoleucine, cysteine, methionine, lysine, phenylalanine, and proline. The effect of insulin on glucose incorporation into triglyceride is also severely diminished by these amino acids. In addition, alanine reduced the incorporation of precursors ([U-14C]glucose or [1-14C]palmitate) into triglyceride both in vitro and in vivo. The Ki values of alanine were 0.4 and 0.5 mM toward the precursors of glucose and palmitate, respectively. The mechanism of reduction of insulin responsiveness in rat adipose tissue is discussed on the basis of these results. PMID:7016847

  19. L-leucine transport systems in Saccharomyces cerevisiae participation of GAP1, S1 and S2 transport systems.

    PubMed

    Kotliar, N; Stella, C A; Ramos, E H; Mattoon, J R

    1994-09-01

    L-leucine uptake in Saccharomyces cerevisiae is mediated by three different transport systems, S1, S2 and GAP1. Their activities are dependent on the nitrogen source of the culture media. Wild type cells grown in L-proline exhibit a single transport system with high affinity and high Vmax that is partially inhibited by L-citrulline. A gap1 mutant shows two transport systems with Km and Vmax values similar to those previously described as S1 and S2, this transport activity is not inhibited by D-leucine, D-isoleucine or D-valine. Two systems can be also determined in wild type cells grown in rich medium containing a mixed nitrogen source where decreased GAP1 function is observed. In either wild type or gap1 cells grown in medium containing ammonium ions as sole nitrogen source, L-leucine uptake kinetics shows two systems with lower Vmax and similar Km values to those of the S1 and S2 systems. These results show that in S. cerevisiae GAP1, S1 and S2 participate in L-leucine entrance in cells grown in a poor nitrogen source, and that S1 and S2 are two ammonia-sensitive permeases that mediate the uptake in cells grown in a rich nitrogen source. PMID:7812191

  20. Leucine induced dephosphorylation of Sestrin2 promotes mTORC1 activation.

    PubMed

    Kimball, Scot R; Gordon, Bradley S; Moyer, Jenna E; Dennis, Michael D; Jefferson, Leonard S

    2016-08-01

    The studies described herein were designed to explore the role of Sestrin2 in mediating the selective action of leucine to activate mTORC1. The results demonstrate that Sestrin2 is a phosphoprotein and that its phosphorylation state is responsive to the availability of leucine, but not other essential amino acids. Moreover, leucine availability-induced alterations in Sestrin2 phosphorylation correlated temporally and dose dependently with the activation state of mTORC1, there being a reciprocal relationship between the degree of phosphorylation of Sestrin2 and the extent of repression of mTORC1. With leucine deprivation, Sestrin2 became more highly phosphorylated and interacted more strongly with proteins of the GATOR2 complex. Notably, in cells lacking the protein kinase ULK1, the activation state of mTORC1 was elevated in leucine-deficient medium, such that the effect of re-addition of the amino acid was blunted. In contrast, overexpression of ULK1 led to hyperphosphorylation of Sestrin2 and enhanced its interaction with GATOR2. Neither rapamycin nor Torin2 had any effect on Sestrin2 phosphorylation, suggesting that leucine deprivation-induced repression of mTORC1 was not responsible for the action of ULK1 on Sestrin2. Mass spectrometry analysis of Sestrin2 revealed three phosphorylation sites that are conserved across mammalian species. Mutation of the three sites to phospho-mimetic amino acids in exogenously expressed Sestrin2 promoted its interaction with GATOR2 and dramatically repressed mTORC1 even in the presence of leucine. Overall, the results support a model in which leucine selectively promotes dephosphorylation of Sestrin2, causing it to dissociate from and thereby activate GATOR2, leading to activation of mTORC1. PMID:27010498

  1. Metabolic Responses of Saccharomyces cerevisiae to Valine and Ammonium Pulses during Four-Stage Continuous Wine Fermentations

    PubMed Central

    Clement, T.; Perez, M.; Mouret, J. R.; Sanchez, I.; Sablayrolles, J. M.

    2013-01-01

    Nitrogen supplementation, which is widely used in winemaking to improve fermentation kinetics, also affects the products of fermentation, including volatile compounds. However, the mechanisms underlying the metabolic response of yeast to nitrogen additions remain unclear. We studied the consequences for Saccharomyces cerevisiae metabolism of valine and ammonium pulses during the stationary phase of four-stage continuous fermentation (FSCF). This culture technique provides cells at steady state similar to that of the stationary phase of batch wine fermentation. Thus, the FSCF device is an appropriate and reliable tool for individual analysis of the metabolic rerouting associated with nutrient additions, in isolation from the continuous evolution of the environment in batch processes. Nitrogen additions, irrespective of the nitrogen-containing compound added, substantially modified the formation of fermentation metabolites, including glycerol, succinate, isoamyl alcohol, propanol, and ethyl esters. This flux redistribution, fulfilling the requirements for precursors of amino acids, was consistent with increased protein synthesis resulting from increased nitrogen availability. Valine pulses, less efficient than ammonium addition in increasing the fermentation rate, were followed by a massive conversion of this amino acid in isobutanol and isobutyl acetate through the Ehrlich pathway. However, additional routes were involved in valine assimilation when added in stationary phase. Overall, we found that particular metabolic changes may be triggered according to the nature of the amino acid supplied, in addition to the common response. Both these shared and specific modifications should be considered when designing strategies to modulate the production of volatile compounds, a current challenge for winemakers. PMID:23417007

  2. Metabolic responses of Saccharomyces cerevisiae to valine and ammonium pulses during four-stage continuous wine fermentations.

    PubMed

    Clement, T; Perez, M; Mouret, J R; Sanchez, I; Sablayrolles, J M; Camarasa, C

    2013-04-01

    Nitrogen supplementation, which is widely used in winemaking to improve fermentation kinetics, also affects the products of fermentation, including volatile compounds. However, the mechanisms underlying the metabolic response of yeast to nitrogen additions remain unclear. We studied the consequences for Saccharomyces cerevisiae metabolism of valine and ammonium pulses during the stationary phase of four-stage continuous fermentation (FSCF). This culture technique provides cells at steady state similar to that of the stationary phase of batch wine fermentation. Thus, the FSCF device is an appropriate and reliable tool for individual analysis of the metabolic rerouting associated with nutrient additions, in isolation from the continuous evolution of the environment in batch processes. Nitrogen additions, irrespective of the nitrogen-containing compound added, substantially modified the formation of fermentation metabolites, including glycerol, succinate, isoamyl alcohol, propanol, and ethyl esters. This flux redistribution, fulfilling the requirements for precursors of amino acids, was consistent with increased protein synthesis resulting from increased nitrogen availability. Valine pulses, less efficient than ammonium addition in increasing the fermentation rate, were followed by a massive conversion of this amino acid in isobutanol and isobutyl acetate through the Ehrlich pathway. However, additional routes were involved in valine assimilation when added in stationary phase. Overall, we found that particular metabolic changes may be triggered according to the nature of the amino acid supplied, in addition to the common response. Both these shared and specific modifications should be considered when designing strategies to modulate the production of volatile compounds, a current challenge for winemakers. PMID:23417007

  3. Use of the valine biosynthetic pathway to convert glucose into isobutanol.

    PubMed

    Savrasova, Ekaterina A; Kivero, Aleksander D; Shakulov, Rustem S; Stoynova, Nataliya V

    2011-09-01

    Microbiological synthesis of higher alcohols (1-butanol, isobutanol, 2-methyl-1-butanol, etc.) from plant biomass is critically important due to their advantages over ethanol as a motor fuel. In recent years, the use of branched-chain amino acid (BCAA) biosynthesis pathways together with heterologous Ehrlich pathway enzyme system (Hazelwood et al. in Appl Environ Microbiol 74:2259-2266, 2008) has been proposed by the Liao group as an alternative approach to aerobic production of higher alcohols as new-generation biofuels (Atsumi et al. in Nature 451:86-90, 2008; Atsumi et al. in Appl Microbiol Biotechnol 85:651-657, 2010; Cann and Liao in Appl Microbiol Biotechnol 81:89-98, 2008; Connor and Liao in Appl Environ Microbiol 74:5769-5775, 2008; Shen and Liao in Metab Eng 10:312-320, 2008; Yan and Liao in J Ind Microbiol Biotechnol 36:471-479, 2009). On the basis of these remarkable investigations, we re-engineered Escherichia coli valine-producing strain H-81, which possess overexpressed ilvGMED operon, for the aerobic conversion of sugar into isobutanol. To redirect valine biosynthesis to the production of alcohol, we also--as has been demonstrated previously (Atsumi et al. in Nature 451:86-90, 2008; Atsumi et al. in Appl Microbiol Biotechnol 85:651-657, 2010; Cann and Liao in Appl Microbiol Biotechnol 81:89-98, 2008; Connor and Liao in Appl Environ Microbiol 74:5769-5775, 2008; Shen and Liao in Metab Eng 10:312-320, 2008; Yan and Liao in J Ind Microbiol Biotechnol 36:471-479, 2009)--used enzymes of Ehrlich pathway. In particular, in our study, the following heterologous proteins were exploited: branched-chain 2-keto acid decarboxylase (BCKAD) encoded by the kdcA gene from Lactococcus lactis with rare codons substituted, and alcohol dehydrogenase (ADH) encoded by the ADH2 gene from Saccharomyces cerevisiae. We show that expression of both of these genes in the valine-producing strain H-81 results in accumulation of isobutanol instead of valine. Expression of BCKAD

  4. A Role for the Kp Leucine Zipper in Regulating P Element Transposition in Drosophila Melanogaster

    PubMed Central

    Andrews, J. D.; Gloor, G. B.

    1995-01-01

    The KP element can repress P element mobility in Drosophila melanogaster. Three mutant KP elements were made that had either two amino acid substitutions or a single amino acid deletion in the putative leucine zipper domain found in the KP polypeptide. Each KP element was expressed from the actin 5C proximal promoter. The wild-type control construct strongly repressed P element mobility, measured by the GD sterility and sn(w) mutability assays, in a position-independent manner. The single amino acid deletion mutant failed to repress P mobility regardless of its insertion site, while repression of P element mobility by the double amino acid substitution mutants was position dependent. The results show that the leucine zipper of the KP polypeptide is important for P element regulation. This supports the multimer-poisoning model of P element repression, because leucine zipper motifs are involved in protein-protein interactions. PMID:8647395

  5. Leptin Signaling Is Required for Leucine Deprivation-enhanced Energy Expenditure*

    PubMed Central

    Zhang, Qian; Liu, Bin; Cheng, Ying; Meng, Qingshu; Xia, Tingting; Jiang, Lei; Chen, Shanghai; Liu, Yong; Guo, Feifan

    2014-01-01

    Leptin signaling in the hypothalamus is crucial in energy homeostasis. We have previously shown that dietary deprivation of the essential amino acid leucine in mice stimulates fat loss by increasing energy expenditure. The involvement of leptin signaling in this regulation, however, has not been reported. Here, we show that leucine deprivation promotes leptin signaling in mice maintained on an otherwise normal diet and restores leptin responses in mice maintained on a high fat diet, a regimen known to induce leptin resistance. In addition, we found that leucine deprivation stimulated energy expenditure, and fat loss was largely blocked in db/db mice homozygous for a mutation in leptin receptor and a knock-in mouse line Y3F with abrogation of leptin receptor Tyr1138-mediated signal transducer and activator transcript 3 signaling. Overall, our studies describe a novel link between hypothalamic leptin signaling and stimulation of energy expenditure under leucine deprivation. PMID:24302741

  6. Sestrin2 is a leucine sensor for the mTORC1 pathway.

    PubMed

    Wolfson, Rachel L; Chantranupong, Lynne; Saxton, Robert A; Shen, Kuang; Scaria, Sonia M; Cantor, Jason R; Sabatini, David M

    2016-01-01

    Leucine is a proteogenic amino acid that also regulates many aspects of mammalian physiology, in large part by activating the mTOR complex 1 (mTORC1) protein kinase, a master growth controller. Amino acids signal to mTORC1 through the Rag guanosine triphosphatases (GTPases). Several factors regulate the Rags, including GATOR1, aGTPase-activating protein; GATOR2, a positive regulator of unknown function; and Sestrin2, a GATOR2-interacting protein that inhibits mTORC1 signaling. We find that leucine, but not arginine, disrupts the Sestrin2-GATOR2 interaction by binding to Sestrin2 with a dissociation constant of 20 micromolar, which is the leucine concentration that half-maximally activates mTORC1. The leucine-binding capacity of Sestrin2 is required for leucine to activate mTORC1 in cells. These results indicate that Sestrin2 is a leucine sensor for the mTORC1 pathway. PMID:26449471

  7. Sestrin2 is a leucine sensor for the mTORC1 pathway

    PubMed Central

    Wolfson, Rachel L.; Chantranupong, Lynne; Saxton, Robert A.; Shen, Kuang; Scaria, Sonia M.; Cantor, Jason R.; Sabatini, David M.

    2015-01-01

    Leucine is a proteogenic amino acid that also regulates many aspects of mammalian physiology, in large part by activating the mTOR complex 1 (mTORC1) protein kinase, a master growth controller. Amino acids signal to mTORC1 through the Rag guanine triphosphatases (GTPases). Several factors regulate the Rags, including GATOR1, a GTPase activating protein (GAP); GATOR2, a positive regulator of unknown function; and Sestrin2, a GATOR2-interacting protein that inhibits mTORC1 signaling. We find that leucine, but not arginine, disrupts the Sestrin2-GATOR2 interaction by binding to Sestrin2 with a Kd of 20 µM, which is the leucine concentration that half-maximally activates mTORC1. The leucine-binding capacity of Sestrin2 is required for leucine to activate mTORC1 in cells. These results indicate that Sestrin2 is a leucine sensor for the mTORC1 pathway. PMID:26449471

  8. Leucine supplementation of a low-protein meal increases skeletal muscle and visceral tissue protein synthesis in neonatal pigs by stimulating mTOR-dependent translation initiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protein synthesis and eukaryotic initiation factor (eIF) activation are increased in skeletal muscle of neonatal pigs parenterally infused with amino acids. Leucine appears to be the most effective single amino acid to trigger these effects. To examine the response to enteral leucine supplementation...

  9. Determination of the safety of leucine supplementation in healthy elderly men.

    PubMed

    Rasmussen, Betina; Gilbert, Erin; Turki, Abrar; Madden, Kenneth; Elango, Rajavel

    2016-07-01

    Leucine, a branched-chain amino acid (BCAA), has been shown to stimulate muscle protein synthesis, and thus has been proposed to prevent age-related muscle atrophy (sarcopenia). Therefore, leucine supplementation may have potential benefits in elderly populations to preserve muscle mass. The tolerable upper intake level (UL) for leucine intake in young men has recently been determined to be 500 mg kg(-1) day(-1), and increases in blood ammonia concentrations were seen at intake levels above 500 mg kg(-1) day(-1); the UL for leucine in elderly is unknown. The objective of the current study was to determine the safety of leucine supplementation in healthy elderly men. Six healthy elderly men (72.2 ± 3.5 years) received graded stepwise increases in leucine intakes ranging from 50 to 750 mg kg(-1) day(-1), on eight separate study days. Plasma and urinary biochemical variables, including blood ammonia, and an oral primed-continuous protocol of L-1-(13)C-Leucine was performed. Blood ammonia concentrations above normal values (35 µmol/L) were observed at leucine intakes >550 mg kg(-1) day(-1). Leucine oxidation measured as a F(13)CO2 (rate of label tracer oxidation) increased with increasing leucine intakes and started to plateau after 450 mg kg(-1) day(-1). Two-phased linear regression analysis of the F(13)CO2 data revealed a breakpoint of 431 mg kg(-1) day(-1) (R (2) = 0.73), suggesting that the upper limit to oxidize leucine was reached at that point. Taking the data together the upper limit for leucine intake in healthy elderly could be set similar to young men at 500 mg kg(-1) day(-1) or ~35 g/day for an individual weighing 70 kg. PMID:27138628

  10. Umbilical uptake of amino acids in the unstressed fetal lamb.

    PubMed Central

    Lemons, J A; Adcock, E W; Jones, M D; Naughton, M A; Meschia, G; Battaglia, F C

    1976-01-01

    The whole blood concentrations of 22 amino acids were measured in a chronic, unstressed fetal lamb preparations. Samples were taken daily from the umbilical artery, umbilical vein, and maternal artery over the latter quarter of gestation. 73 sets of samples (from the umbilical artery and vein and the maternal artery) from 13 animals were analyzed for amino acid levels. Oxygen contents were determined simultaneously in 48 sets (umbilical artery and vein) to relate fetal oxygen consumption to amino acid uptake via the umbilical circulation. The results indicate that there is no umbilical uptake of the acidic amino acids, glutamate and aspartate; there is, in fact, a net flux of glutamate out of the fetus into the placenta. As both of these amino acids are major constituents of body proteins, the data indicate that they are formed within the fetus. The umbilical uptake of some neutral and basic amino acids (e.g., valine, leucine, isoleucine, arginine, phenylalanine, and tyrosine) is in considerable excess of estimated growth requirements, suggesting that some amino acids undergo extensive transamination and oxidative degradation in the fetus. Finally, the net uptake of nitrogen, carbon, and calories by the growing ovine fetus in the form of amino acids, glucose, and lactate is compared to estimated requirements as determined in previous studies. PMID:1033209

  11. Uniquely Localized Intra-Molecular Amino Acid Concentrations at the Glycolytic Enzyme Catalytic/Active Centers of Archaea, Bacteria and Eukaryota are Associated with Their Proposed Temporal Appearances on Earth

    NASA Astrophysics Data System (ADS)

    Pollack, J. Dennis; Gerard, David; Pearl, Dennis K.

    2013-04-01

    The distributions of amino acids at most-conserved sites nearest catalytic/active centers (C/AC) in 4,645 sequences of ten enzymes of the glycolytic Embden-Meyerhof-Parnas pathway in Archaea, Bacteria and Eukaryota are similar to the proposed temporal order of their appearance on Earth. Glycine, isoleucine, leucine, valine, glutamic acid and possibly lysine often described as prebiotic, i.e., existing or occurring before the emergence of life, were localized in positional and conservational defined aggregations in all enzymes of all Domains. The distributions of all 20 biologic amino acids in most-conserved sites nearest their C/ACs were quite different either from distributions in sites less-conserved and further from their C/ACs or from all amino acids regardless of their position or conservation. The major concentrations of glycine, e.g., perhaps the earliest prebiotic amino acid, occupies ≈16 % of all the most-conserved sites within a volume of ≈7-8 Å radius from their C/ACs and decreases linearly towards the molecule's peripheries. Spatially localized major concentrations of isoleucine, leucine and valine are in the mid-conserved and mid-distant sites from their C/ACs in protein interiors. Lysine and glutamic acid comprise ≈25-30 % of all amino acids within an irregular volume bounded by ≈24-28 Å radii from their C/ACs at the most-distant least-conserved sites. The unreported characteristics of these amino acids: their spatially and conservationally identified concentrations in Archaea, Bacteria and Eukaryota, suggest some common structural organization of glycolytic enzymes that may be relevant to their evolution and that of other proteins. We discuss our data in relation to enzyme evolution, their reported prebiotic putative temporal appearances on Earth, abundances, biological "cost", neighbor-sequence preferences or "ordering" and some thermodynamic parameters.

  12. Uniquely localized intra-molecular amino acid concentrations at the glycolytic enzyme catalytic/active centers of Archaea, Bacteria and Eukaryota are associated with their proposed temporal appearances on earth.

    PubMed

    Pollack, J Dennis; Gerard, David; Pearl, Dennis K

    2013-04-01

    The distributions of amino acids at most-conserved sites nearest catalytic/active centers (C/AC) in 4,645 sequences of ten enzymes of the glycolytic Embden-Meyerhof-Parnas pathway in Archaea, Bacteria and Eukaryota are similar to the proposed temporal order of their appearance on Earth. Glycine, isoleucine, leucine, valine, glutamic acid and possibly lysine often described as prebiotic, i.e., existing or occurring before the emergence of life, were localized in positional and conservational defined aggregations in all enzymes of all Domains. The distributions of all 20 biologic amino acids in most-conserved sites nearest their C/ACs were quite different either from distributions in sites less-conserved and further from their C/ACs or from all amino acids regardless of their position or conservation. The major concentrations of glycine, e.g., perhaps the earliest prebiotic amino acid, occupies ≈ 16 % of all the most-conserved sites within a volume of ≈ 7-8 Å radius from their C/ACs and decreases linearly towards the molecule's peripheries. Spatially localized major concentrations of isoleucine, leucine and valine are in the mid-conserved and mid-distant sites from their C/ACs in protein interiors. Lysine and glutamic acid comprise ≈ 25-30 % of all amino acids within an irregular volume bounded by ≈ 24-28 Å radii from their C/ACs at the most-distant least-conserved sites. The unreported characteristics of these amino acids: their spatially and conservationally identified concentrations in Archaea, Bacteria and Eukaryota, suggest some common structural organization of glycolytic enzymes that may be relevant to their evolution and that of other proteins. We discuss our data in relation to enzyme evolution, their reported prebiotic putative temporal appearances on Earth, abundances, biological "cost", neighbor-sequence preferences or "ordering" and some thermodynamic parameters. PMID:23715690

  13. The effect of sugar, amino acid, metal ion, and NaCl on model Maillard reaction under pH control.

    PubMed

    Kwak, E-J; Lim, S-I

    2004-08-01

    The color intensities was determined of Maillard reaction products (MRPs) prepared by heating each of five sugars (maltose, fructose, glucose, arabinose, and xylose) with each of 12 amino acids (aspartic acid, glutamic acid, alanine, leucine, isoleucine, valine, proline, serine, cysteine, phenylalanine, arginine, and lysine). The remaining percentages of glucose and rate of change of color intensity due to the addition of a metal ion and NaCl were monitored for nine MRPs that had been formed between glucose and each of nine amino acids (aspartic acid, glutamic acid, alanine, valine, serine, cysteine, phenylalanine, arginine, and lysine). Model MRPs were prepared in a block heater at 100 degrees C for 1-12 h with the pH value controlled at 6.5. The resulting color intensity of each MRPs formed from the basic amino acids was greater due to the higher reactivity than those from the acidic amino acids. The remaining percentage of glucose in each MRPs from the basic amino acids was lower than those from the acidic amino acids. The MRPs from the nonpolar amino acids showed an intermediate color intensity and remaining percentages of glucose between those formed from the basic and acidic amino acids. Browning tended to be accelerated in the presence of metal ions, especially Fe2+ and Cu2+, although it was affected by the property of the amino acid and heating time as well as by the type of metal ion. On the other hand, browning was greatly inhibited by a high concentration of NaCl. PMID:15309575

  14. Pyruvate decarboxylase catalyzes decarboxylation of branched-chain 2-oxo acids but is not essential for fusel alcohol production by Saccharomyces cerevisiae.

    PubMed

    ter Schure, E G; Flikweert, M T; van Dijken, J P; Pronk, J T; Verrips, C T

    1998-04-01

    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

  15. Protein Ingestion Induces Muscle Insulin Resistance Independent of Leucine-Mediated mTOR Activation

    PubMed Central

    Smith, Gordon I.; Yoshino, Jun; Stromsdorfer, Kelly L.; Klein, Seth J.; Magkos, Faidon; Reeds, Dominic N.; Klein, Samuel

    2015-01-01

    Increased plasma branched-chain amino acid concentrations are associated with insulin resistance, and intravenous amino acid infusion blunts insulin-mediated glucose disposal. We tested the hypothesis that protein ingestion impairs insulin-mediated glucose disposal by leucine-mediated mTOR signaling, which can inhibit AKT. We measured glucose disposal and muscle p-mTORSer2448, p-AKTSer473, and p-AKTThr308 in 22 women during a hyperinsulinemic-euglycemic clamp procedure with and without concomitant ingestion of whey protein (0.6 g/kg fat-free mass; n = 11) or leucine that matched the amount given with whey protein (n = 11). Both whey protein and leucine ingestion raised plasma leucine concentration by approximately twofold and muscle p-mTORSer2448 by ∼30% above the values observed in the control (no amino acid ingestion) studies; p-AKTSer473 and p-AKTThr308 were not affected by whey protein or leucine ingestion. Whey protein ingestion decreased insulin-mediated glucose disposal (median 38.8 [quartiles 30.8, 61.8] vs. 51.9 [41.0, 77.3] µmol glucose/µU insulin · mL−1 · min−1; P < 0.01), whereas ingestion of leucine did not (52.3 [43.3, 65.4] vs. 52.3 [43.9, 73.2]). These results indicate that 1) protein ingestion causes insulin resistance and could be an important regulator of postprandial glucose homeostasis and 2) the insulin-desensitizing effect of protein ingestion is not due to inhibition of AKT by leucine-mediated mTOR signaling. PMID:25475435

  16. Isolation and characterization of valine dehydrogenase from Streptomyces aureofaciens.

    PubMed Central

    Vancurová, I; Vancura, A; Volc, J; Neuzil, J; Flieger, M; Basarová, G; Bĕhal, V

    1988-01-01

    Valine dehydrogenase was purified to homogeneity from the crude extracts of Streptomyces aureofaciens. The molecular weight of the native enzyme was 116,000 by equilibrium ultracentrifugation and 118,000 by size exclusion high-performance liquid chromatography. The enzyme was composed of four subunits with molecular weights of 29,000. The isoelectric point was 5.1. The enzyme required NAD+ as a cofactor, which could not be replaced by NADP+. Sulfhydryl reagents inhibited the enzyme activity. The pH optimum was 10.7 for oxidative deamination of L-valine and 9.0 for reductive amination of alpha-ketoisovalerate. The Michaelis constants were 2.5 mM for L-valine and 0.10 mM for NAD+. For reductive amination the Km values were 1.25 mM for alpha-ketoisovalerate, 0.023 mM for NADH, and 18.2 mM for NH4Cl. Images PMID:3182727

  17. Partitioning of amino acids in the aqueous biphasic system containing the water-miscible ionic liquid 1-butyl-3-methylimidazolium bromide and the water-structuring salt potassium citrate.

    PubMed

    Zafarani-Moattar, Mohammed Taghi; Hamzehzadeh, Sholeh

    2011-07-01

    In biotechnology, extraction by means of aqueous biphasic systems (ABS) is known as a promising tool for the recovery and purification of bio-molecules. Over the past decade, the increasing emphasis on cleaner and environmentally benign extraction procedures has led to enhanced interest in the ABS containing ionic liquids (ILs)-a new class of non-volatile alternative solvents. ABS composed of the hydrophilic IL {1-butyl-3-methylimidazolium bromide ([C4 mim]Br)} and potassium citrate-which is easily degraded-represents a clean media to green separation of bio-molecules. In this regard, here, the extraction capability of this ABS was evaluated through its application to the extraction of some amino acids. To gain an insight into the driving forces of amino acid partitioning in the studied IL-based ABS, the distribution of five model amino acids (L-tryptophan, L-phenylalanine, L-tyrosine, L-leucine, and L-valine) at different aqueous medium pH values and different phase compositions was investigated. The studies indicated that hydrophobic interactions were the main driving force, although electrostatic interactions and salting-out effects were also important for the transfer of the amino acids. Moreover, based on the statistical analysis of the driving forces of amino acid partitioning in the studied IL-based ABS, a model was established to describe the partition coefficient of three model amino acids, L-tryptophan, L-phenylalanine, and L-valine, and employed to predict the partition coefficient of two other model amino acids, L-tyrosine and L-leucine. PMID:21509956

  18. IGFBP-1 hyperphosphorylation in response to leucine deprivation is mediated by the AAR pathway.

    PubMed

    Malkani, Niyati; Jansson, Thomas; Gupta, Madhulika B

    2015-09-01

    Insulin-like growth factor-1 (IGF-I) is the key regulator of fetal growth. IGF-I bioavailability is markedly diminished by IGF binding protein-1 (IGFBP-1) phosphorylation. Leucine deprivation strongly induces IGFBP-1 hyperphosphorylation, and plays an important role in fetal growth restriction (FGR). FGR is characterized by decreased amino acid availability, which activates the amino acid response (AAR) and inhibits the mechanistic target of rapamycin (mTOR) pathway. We investigated the role of AAR and mTOR in mediating IGFBP-1 secretion and phosphorylation in HepG2 cells in leucine deprivation. mTOR inhibition (rapamycin or raptor + rictor siRNA), or activation (DEPTOR siRNA) demonstrated a role of mTOR in leucine deprivation-induced IGFBP-1 secretion but not phosphorylation. When the AAR was blocked (U0126, or ERK/GCN2 siRNA), both IGFBP-1 secretion and hyperphosphorylation (pSer101/pSer119/pSer169) due to leucine deprivation were prevented. CK2 inhibition by TBB also attenuated IGFBP-1 phosphorylation in leucine deprivation. These results suggest that the AAR and mTOR independently regulate IGFBP-1 secretion and phosphorylation in response to decreased amino acid availability. PMID:25957086

  19. Facile fabrication of superhydrophobic flower-like polyaniline architectures by using valine as a dopant in polymerization

    NASA Astrophysics Data System (ADS)

    Sun, Jun; Bi, Hong

    2012-03-01

    A facile method was developed to fabricate superhydrophobic, flower-like polyanline (PANI) architectures with hierarchical nanostructures by adding valine in polymerization as a dopant. The water contact angle of the prepared PANI film was measured to be 155.3°, and the hydrophobic surface of the PANI architectures can be tuned easily by varying the polymerization time as well as valine doping quantity. It is believed that valine plays an important role in not only growth of the hierarchical PANI structures but also formation of the superhydrophobic surface, for it provides functional groups such as sbnd COOH, sbnd NH2 and a hydrophobic terminal group which may further increase intra-/inter-molecular interactions including hydrogen bonding, π-π stacking and hydrophobic properties. Similar flower-like PANI architectures have been prepared successfully by employing other amino acids such as threonine, proline and arginine. This method makes it possible for widespread applications of superhydrophobic PANI film due to its simplicity and practicability.

  20. Changes in intramuscular amino acid levels in submaximally exercised horses - a pilot study.

    PubMed

    van den Hoven, R; Bauer, A; Hackl, S; Zickl, M; Spona, J; Zentek, J

    2010-08-01

    The time-dependent changes in intramuscular amino acid (AA) levels caused by exercise and by feeding a protein/AA supplement were analysed in nine horses. Horses were submitted to a total of four standardized exercise tests (SETs). Amino acid concentrations were determined prior to, immediately after, 4 and 18 h after exercise. The experiment was subdivided into two consecutive periods of 3 weeks. In each period two SETs were performed. In the second period, horses were given a protein/AA supplement within 1 h after exercise. Significant changes in mean plasma AA levels similar to previous studies were noted to be time-dependent and to be associated with feeding the supplement. The intramuscular concentrations of the free AA in relation to pre-exercise levels showed significant time-dependent changes for alanine, asparagine, aspartate, citrulline, glutamine, glycine, isoleucine, leucine, methionine, serine, taurine, threonine, tyrosine and valine. Feeding the supplement significantly increased the 4 h post-exercise intramuscular concentration of alanine, isoleucine, methionine and tyrosine. At 18 h after exercise, apart from isoleucine and methionine, levels were still increased and also those of asparagine, histidine and valine in relation to none treatment. Hence, it was concluded that AA mixtures administered orally to horses within 1 h after exercise increased intramuscular AA pool. PMID:19663973

  1. Distinctive amino acid composition profiles in salivary proteins of the tick Ixodes scapularis

    PubMed Central

    Hughes, Austin L.; Friedman, Robert

    2012-01-01

    Bioinformatic analysis of the amino acid composition of proteins of the tick Ixodes scapularis showed that, in comparison to other secreted proteins, salivary proteins in general have higher frequencies of polar residues and lower frequencies of the non-polar residues leucine and valine. Computer prediction of linear B-cell epitopes showed that polar residues were associated with the presence of high-quality epitopes and that tick salivary proteins included significantly more proteins with predicted high-quality epitopes than did other secreted proteins. The results provided no evidence that salivary proteins as a whole have evolved characteristics minimizing their antigenicity to the vertebrate host. Certain salivary proteins may indeed have evolved low antigenicity, but the I. scapularis sialome include at least some apparently antigenic proteins that might be tested experimentally to determine whether they would be suitable candidates for anti-tick vaccines. PMID:22108016

  2. Application of Pre-Column Labeling Liquid Chromatography for Canine Plasma-Free Amino Acid Analysis.

    PubMed

    Azuma, Kazuo; Hirao, Yoshiko; Hayakawa, Yoshihiro; Murahata, Yusuke; Osaki, Tomohiro; Tsuka, Takeshi; Imagawa, Tomohiro; Okamoto, Yoshiharu; Ito, Norihiko

    2016-01-01

    Plasma-free amino acid (PFAA) levels are a useful metric for diagnosing cancer and providing a prognosis. However, the use of analysis of PFAA levels has been limited in the veterinary medicine field. We addressed the application of liquid chromatography (LC) using a pre-column labeling technique for analysis of canine PFAA levels. This method significantly shortened the analysis time relative to conventional methods. No diurnal fluctuations were detected at 9:00 AM in most PFAA levels, and food intake increased the levels of some PFAAs, including valine, leucine, tyrosine, phenylalanine, and proline. These results indicate that LC with pre-column labeling is useful for measuring canine PFAA levels, for which time of day and interval after food intake must be taken into consideration. PMID:26771650

  3. Application of Pre-Column Labeling Liquid Chromatography for Canine Plasma-Free Amino Acid Analysis

    PubMed Central

    Azuma, Kazuo; Hirao, Yoshiko; Hayakawa, Yoshihiro; Murahata, Yusuke; Osaki, Tomohiro; Tsuka, Takeshi; Imagawa, Tomohiro; Okamoto, Yoshiharu; Ito, Norihiko

    2016-01-01

    Plasma-free amino acid (PFAA) levels are a useful metric for diagnosing cancer and providing a prognosis. However, the use of analysis of PFAA levels has been limited in the veterinary medicine field. We addressed the application of liquid chromatography (LC) using a pre-column labeling technique for analysis of canine PFAA levels. This method significantly shortened the analysis time relative to conventional methods. No diurnal fluctuations were detected at 9:00 AM in most PFAA levels, and food intake increased the levels of some PFAAs, including valine, leucine, tyrosine, phenylalanine, and proline. These results indicate that LC with pre-column labeling is useful for measuring canine PFAA levels, for which time of day and interval after food intake must be taken into consideration. PMID:26771650

  4. Role of uptake of (14C)valine into protein in the development of tolerance to diisopropylphosphorofluoridate (DFP) toxicity

    SciTech Connect

    Gupta, R.C.; Dettbarn, W.D.

    1986-07-01

    In a subchronic toxicity study male Sprague-Dawley rats were daily treated with diisopropylphosphorofluoridate (DFP) (0.5 mg/kg, sc) for 14 days. Maximum signs of anticholinesterase toxicity were observed during Days 4 and 5 comparable to those seen 10-15 min following a single sublethal dosage (1.5 mg DFP/kg, sc). Signs disappeared after Days 6-7 of exposure and rats became apparently normal during the remainder of the treatment period. Significant hypothermia was seen following the second to fifth doses with maximum effect after the fifth injection. Subsequent injections of DFP did not cause any reduction in temperature. Incorporation of (/sup 14/C)valine was measured 24 hr after the 5th and 14th injections of DFP, at a time when body temperature had recovered to control values. The rate of in vivo incorporation of (/sup 14/C)valine was measured 0.5, 1.0, and 2.0 hr after a subcutaneous injection of L-(1-/sup 14/C)valine at a dose of 5 microCi/mmol/100 g body wt. After five injections the rate of L-(1-/sup 14/C)valine uptake into the free amino acid pool and the incorporation into the protein bound pool was significantly (p less than 0.01) reduced in discrete brain regions, liver, kidney, and skeletal muscles. At the end of the 14-day treatment, protein synthesis in all the skeletal muscles tested had recovered completely (p greater than 0.01) to the values of nontreated control animals. In brain, liver, and kidney, however, no recovery was seen during this period. The recovery of protein synthesis in skeletal muscle may be one of the mechanisms that lead to tolerance development during prolonged administration of subacute concentrations of DFP.

  5. Leucine modulates peptide transport system-1 across the blood-brain barrier at the stereospecific site within the central nervous system.

    PubMed

    Banks, W A; Kastin, A J

    1991-04-01

    Previous results have shown that leucine injected into a cerebral ventricle (i.c.v.) can act as an allosteric regulator of peptide transport system-1 (PTS-1), the system that transports Tyr-Pro-Leu-Gly-NH2 (Tyr-MIF-1) and the enkephalins out of the central nervous system (CNS). D-Leucine appeared more potent than L-leucine. In the current study, dose-response curves were constructed for each compound after both intravenous (i.v.) and i.c.v. injection. Based on ED50 values after i.c.v. injection, D-leucine was about 200 times more potent than L-leucine in its inhibition of PTS-1, thereby confirming stereospecificity of the allosteric site. D- and L-Leucine were also more potent when given i.c.v. than when given i.v., suggesting that the site is located on the CNS side of the blood-brain barrier (BBB). The finding that D-leucine was less potent than L-leucine when given i.v. is also consistent with a CNS site of action because the L-isomer of leucine has been shown to be preferentially transported into the brain. These findings agree with the previous suggestion that some of the neurotoxic effects of leucine may be mediated through PTS-1 and could help explain how D-amino acids can exert opiate-related effects on the CNS. PMID:1676737

  6. Solubility calculations of branched and linear amino acids using lattice cluster theory

    NASA Astrophysics Data System (ADS)

    Fischlschweiger, Michael; Enders, Sabine; Zeiner, Tim

    2014-09-01

    In this work, the activity coefficients and the solubility of amino acids in water were calculated using the lattice cluster theory (LCT) combined with the extended chemical association lattice model allowing self-association as well as cross-association. This permits the study of the influence of the amino acids structure on the thermodynamic properties for the first time. By the used model, the activity coefficient and solubilities of the investigated fourteen amino acids (glycine, alanine, γ-aminobutyric acid, dl-valine, dl-threonine, dl-methionine, l-leucine, l-glutamic acid, l-proline, hydroxyproline, histidine, l-arginine, α-amino valeric acid) could be described in good accordance with experimental data. In the case of different α-amino acids, but different hydrocarbon chains, the same interaction energy parameter can be used within the LCT. All studied amino acids could be modelled using the same parameter for the description of the amino acid association properties. The formed cross-associates contain more amino acids than expressed by the overall mole fraction of the solution. Moreover, the composition of the cross-associates depends on temperature, where the amount of amino acids increases with increasing temperature.

  7. The impaired intestinal mucosal immune system by valine deficiency for young grass carp (Ctenopharyngodon idella) is associated with decreasing immune status and regulating tight junction proteins transcript abundance in the intestine.

    PubMed

    Luo, Jian-Bo; Feng, Lin; Jiang, Wei-Dan; Liu, Yang; Wu, Pei; Jiang, Jun; Kuang, Sheng-Yao; Tang, Ling; Zhang, Yong-An; Zhou, Xiao-Qiu

    2014-09-01

    This study investigated the effects of dietary valine on the growth, intestinal immune response, tight junction proteins transcript abundance and gene expression of immune-related signaling molecules in the intestine of young grass carp (Ctenopharyngodon idella). Six iso-nitrogenous diets containing graded levels of valine (4.3-19.1 g kg(-)(1) diet) were fed to the fish for 8 weeks. The results showed that percentage weight gain (PWG), feed intake and feed efficiency of fish were the lowest in fish fed the valine-deficient diet (P < 0.05). In addition, valine deficiency decreased lysozyme, acid phosphatase activities and complement 3 content in the intestine (P < 0.05), down-regulated mRNA levels of interleukin 10, transforming growth factor β1, IκBα and target of rapamycin (TOR) (P < 0.05), and up-regulated tumor necrosis factor α, interleukin 8 and nuclear factor κB P65 (NF-κB P65) gene expression (P < 0.05). Additionally, valine deficiency significantly decreased transcript of Occludin, Claudin b, Claudin c, Claudin 3, and ZO-1 (P < 0.05), and improved Claudin 15 expression in the fish intestine (P < 0.05). However, valine did not have a significant effect on expression of Claudin 12 in the intestine of grass carp (P > 0.05). In conclusion, valine deficiency decreased fish growth and intestinal immune status, as well as regulated gene expression of tight junction proteins, NF-κB P65, IκBα and TOR in the fish intestine. Based on the quadratic regression analysis of lysozyme activity or PWG, the dietary valine requirement of young grass carp (268-679 g) were established to be 14.47 g kg(-1) diet (4.82 g 100 g(-1) CP) or 14.00 g kg(-1) diet (4.77 g 100 g(-1) CP), respectively. PMID:25014314

  8. Raman spectra of amino acids and their aqueous solutions

    NASA Astrophysics Data System (ADS)

    Zhu, Guangyong; Zhu, Xian; Fan, Qi; Wan, Xueliang

    2011-03-01

    Amino acids are the basic "building blocks" that combine to form proteins and play an important physiological role in all life-forms. Amino acids can be used as models for the examination of the importance of intermolecular bonding in life processes. Raman spectra serve to obtain information regarding molecular conformation, giving valuable insights into the topology of more complex molecules (peptides and proteins). In this paper, amino acids and their aqueous solution have been studied by Raman spectroscopy. Comparisons of certain values for these frequencies in amino acids and their aqueous solutions are given. Spectra of solids when compared to those of the solute in solution are invariably much more complex and almost always sharper. We present a collection of Raman spectra of 18 kinds of amino acids ( L-alanine, L-arginine, L-aspartic acid, cystine, L-glutamic acid, L-glycine, L-histidine, L-isoluecine, L-leucine, L-lysine, L-phenylalanine, L-methionone, L-proline, L-serine, L-threonine, L-tryptophan, L-tyrosine, L-valine) and their aqueous solutions that can serve as references for the interpretation of Raman spectra of proteins and biological materials.

  9. Amino Acid and Vitamin Requirements of Several Bacteroides Strains

    PubMed Central

    Quinto, Grace

    1966-01-01

    Nutritional studies were performed on nine Bacteroides strains, by use of the methodology and media of anaerobic rumen microbiology. Ristella perfoetens CCI required l-arginine hydrochloride, l-tryptophan, l-leucine, l-histidine hydrochloride, l-cysteine hydrochloride, dl-valine, dl-tyrosine, and the vitamin calcium-d-pantothenate, since scant turbidity developed in media without these nutrients. R. perfoetens was stimulated by glycine, dl-lysine hydrochloride, dl-isoleucine, l-proline, l-glutamic acid, dl-alanine, dl-phenylalanine, dl-methionine, and the vitamins nicotinamide and p-aminobenzoic acid, since maximal turbidity developed more slowly in media without these nutrients than in complete medium. Medium A-23, which was devised for R. perfoetens, contained salts, 0.0002% nicotinamide and calcium d-pantothenate, 0.00001% p-aminobenzoic acid, 0.044% l-tryptophan, 0.09% l-glutamic acid, and 0.1% of the other 13 amino acids listed above. Zuberella clostridiformis and seven strains of R. pseudoinsolita did not require vitamins, and showed no absolute requirement for any one amino acid. Various strains produced maximal turbidity more slowly in media deficient in l-proline, glycine, l-glutamic acid, dl-serine, l-histidine hydrochloride, dl-alanine, or l-cysteine hydrochloride, than in complete medium. These eight strains grew optimally in medium A-23 plus 0.1% dl-serine but without vitamins. PMID:16349673

  10. Fetoplacental deamination and decarboxylation of leucine

    SciTech Connect

    Loy, G.L.; Quick, A.N. Jr.; Hay, W.W. Jr.; Meschia, G.; Battaglia, F.C.; Fennessey, P.V. )

    1990-10-01

    Fetal and placental metabolism of leucine (Leu) and ketoisocaproic acid (KIC) were studied in seven fetal lambs at 132 +/- 1.3-days gestation. Fetal infusions of (1-13C)Leu, (1-14C)Leu, and antipyrine were carried out for 4 h. Uterine and umbilical blood flows were measured using the antipyrine steady-state diffusion technique. Leu and KIC concentrations, (14C)Leu-specific activities, 14CO2, (13C)Leu, and (13C)KIC enrichment (mole percent enrichment) were measured in the maternal artery, uterine vein, and umbilical artery and vein to calculate net fluxes of tracee and tracer molecules between fetus and placenta and between the uteroplacenta and the maternal circulation. There were net Leu and KIC fluxes into the fetus from the placenta with the KIC flux equal to approximately 19% of the combined Leu plus KIC flux. In addition, there was a net KIC flux into the uterine circulation. The fraction of infused tracer Leu escaping the placenta into the mother was small (approximately 6%). By contrast, there was a rapid exchange of tracer Leu carbon between placenta and fetus resulting in a significant flux of labeled KIC from placenta to fetus. Approximately 20% of the infused tracer carbon was converted to CO2 within the fetus. This rate of conversion was greater than 80% of the total fetoplacental conversion rate and significantly higher than the flux of KIC tracer carbon from placenta to fetus. Fetal KIC decarboxylation rate, calculated from the fetal KIC enrichment data, was 2.83 +/- 0.40 mumol.min-1.kg fetus-1 and approximately 60% of the combined net Leu and KIC flux into the fetus from the placenta.

  11. Metabolizable energy, nitrogen balance, and ileal digestibility of amino acids in quality protein maize for pigs

    PubMed Central

    2014-01-01

    Background To compare the nutritional value and digestibility of five quality protein maize (QPM) hybrids to that of white and yellow maize, two experiments were carried out in growing pigs. In experiment 1, the energy metabolizability and the nitrogen balance of growing pigs fed one of five QPM hybrid diets were compared against those of pigs fed white or yellow maize. In experiment 2, the apparent and standardized ileal digestibility (AID and SID, respectively) of proteins and amino acids from the five QPM hybrids were compared against those obtained from pigs fed white and yellow maize. In both experiments, the comparisons were conducted using contrasts. Results The dry matter and nitrogen intakes were higher in the pigs fed the QPM hybrids (P < 0.05) than in the pigs fed white or yellow maize. Energy digestibility (P < 0.001) and metabolizability (P < 0.01) were higher in the pigs fed the white and yellow maize diets than in those fed the QPM diets. The AID of lysine was higher (P < 0.01) in the QPM diets than in the white and yellow maize. The AIDs of leucine, isoleucine, valine, phenylalanine, and methionine were lower in the QPM diets than those of maize (white and yellow) (all P < 0.05). Maize (white and yellow) had greater SIDs of leucine, isoleucine, valine, phenylalanine, glutamic acid, serine, alanine, tyrosine, and proline (P < 0.05). Conclusions Based on these results, it was concluded that QPM had a lower metabolizable energy content and a higher amount of digestible lysine than normal maize. PMID:25045520

  12. Effects of aspartame and glucose administration on brain and plasma levels of large neutral amino acids and brain 5-hydroxyindoles.

    PubMed

    Yokogoshi, H; Roberts, C H; Caballero, B; Wurtman, R J

    1984-07-01

    Administration of the artificial sweetener aspartame (L-aspartylphenylalanylmethyl ester; 200 mg/kg) by gavage to rats caused large increments in brain and plasma levels of phenylalanine and its product tyrosine. Glucose administration (3 g/kg, by gavage, a dose sufficient to cause insulin-mediated reductions in plasma levels of the large neutral amino acids leucine, isoleucine, and valine) also elevated brain phenylalanine and tyrosine, and enhanced the increments caused by the aspartame, nearly doubling the rise in brain phenylalanine. Each animal's brain phenylalanine or tyrosine levels were highly correlated (r = 0.97 and 0.99, respectively) with its plasma phenylalanine or tyrosine ratios, affirming that aspartame's effects on the brain amino acids result from the changes it produces in plasma composition. As described previously, glucose consumption increased brain tryptophan levels, and consequently, brain levels of the 5-hydroxyindoles serotonin and 5-hydroxyindoleacetic acid. Aspartame alone had no effect on these compounds but completely blocked the changes in 5-hydroxyindoles caused by glucose. Each animal's brain level of tryptophan (r = 0.89) and 5-hydroxyindoles (r = 0.74) was also significantly correlated with its plasma tryptophan ratio, affirming that the effects of glucose or aspartame on these brain constituents also result from the changes they produce in plasma composition. The aspartame-glucose combination also reduced brain levels of leucine, isoleucine, and valine to a significantly greater extent than aspartame or glucose alone. These observations indicate that high aspartame doses can generate major neurochemical changes in rats, especially when consumed along with carbohydrate-containing foods. However, they should not in any way be interpreted as demonstrating that aspartame significantly affects the human brain. PMID:6204522

  13. Reduction in plasma leucine after sprint exercise is greater in males than in females.

    PubMed

    Esbjörnsson, M; Rooyackers, O; Norman, B; Rundqvist, H C; Nowak, J; Bülow, J; Simonsen, L; Jansson, E

    2012-06-01

    There is a pronounced gender difference in the accumulation of plasma ammonia after sprint exercise. Ammonia is a key intermediate in amino acid metabolism, which implies that gender-related differences in plasma and muscle amino acid concentrations after sprint exercise exist. To study this, three bouts of 30-s sprint exercise were performed by healthy females (n=8) and males (n=6). Blood leucine and muscle leucine were collected over the exercise period. Basal arterial plasma and skeletal muscle leucine were 40% higher in males than females (P<0.010 and P<0.020). Plasma, but not muscle, leucine decreased by sprint exercise and more so in males than females (g × t: P=0.025). Increase in ammonia was higher in males than females in both plasma and muscle (g × t: P<0.001 and P=0.003). An opposite pattern was shown for plasma glutamine, where an increase was found in females (P<0.001), but not in males. In conclusion, the lower plasma ammonia after sprint exercise in females seems to be explained by a lower accumulation of ammonia in skeletal muscle and by a buffering of ammonia in the form of glutamine in females. The greater reduction in plasma leucine in males seems to be related to their greater increase in muscle ammonia after sprint exercise. PMID:22612362

  14. Functional Profiling Discovers the Dieldrin Organochlorinated Pesticide Affects Leucine Availability in Yeast

    PubMed Central

    Vulpe, Chris D.

    2013-01-01

    Exposure to organochlorinated pesticides such as dieldrin has been linked to Parkinson’s and Alzheimer’s diseases, endocrine disruption, and cancer, but the cellular and molecular mechanisms of toxicity behind these effects remain largely unknown. Here we demonstrate, using a functional genomics approach in the model eukaryote Saccharomyces cerevisiae, that dieldrin alters leucine availability. This model is supported by multiple lines of congruent evidence: (1) mutants defective in amino acid signaling or transport are sensitive to dieldrin, which is reversed by the addition of exogenous leucine; (2) dieldrin sensitivity of wild-type or mutant strains is dependent upon leucine concentration in the media; (3) overexpression of proteins that increase intracellular leucine confer resistance to dieldrin; (4) leucine uptake is inhibited in the presence of dieldrin; and (5) dieldrin induces the amino acid starvation response. Additionally, we demonstrate that appropriate negative regulation of the Ras/protein kinase A pathway, along with an intact pyruvate dehydrogenase complex, is required for dieldrin tolerance. Many yeast genes described in this study have human orthologs that may modulate dieldrin toxicity in humans. PMID:23358190

  15. Activities of the enzymes of the Ehrlich pathway and formation of branched-chain alcohols in Saccharomyces cerevisiae and Candida utilis grown in continuous culture on valine or ammonium as sole nitrogen source.

    PubMed

    Derrick, S; Large, P J

    1993-11-01

    Valine aminotransferase, a key enzyme in both biosynthesis and breakdown of branched-chain amino acids, showed consistently higher activity in Candida utilis grown in continuous culture than in Saccharomyces cerevisiae, while pyruvate decarboxylase and alcohol dehydrogenase, the other two enzymes of the Ehrlich pathway of branched-chain alcohol formation, were lower in activity. By spheroplast lysis, it was shown that valine aminotransferase followed the distribution of pyruvate decarboxylase in being located in the cytosol. Replacement of ammonium as nitrogen source by valine during conditions of carbon or nitrogen limitation caused increased specific activities of these three enzymes in S. cerevisiae, but (with one exception) decreased those of C. utilis. Of the metabolites accumulating in the culture medium, little or no ethanol or branched-chain alcohols were present during carbon-limited growth of either organism, but the change to nitrogen limitation resulted in increases in concentration of 20- to 100-fold in pyruvate, acetate and non-pyruvate keto acids as well as the accumulation of branched-chain alcohols in both organisms, and of ethanol, ethyl acetate and glycerol in S. cerevisiae. When valine was the limiting nitrogen source, there was an increase in non-pyruvate keto acids and a 10- to 16-fold increase in 2-methylpropanol. Total branched-chain alcohols formed under nitrogen limitation were 2-fold higher in S. cerevisiae than in C. utilis, irrespective of nitrogen source. Accumulation of branched-chain alcohols, ethanol, acetate and glycerol was also observed during carbon-limited growth of S. cerevisiae with valine as nitrogen source at dilution rates above the critical rate for transition to respirofermentative growth. Less than 70% of the valine carbon metabolized during growth of S. cerevisiae and only 15% of that used during growth of C. utilis was recovered in identified metabolic products. Even allowing for losses by volatilization during

  16. Stereospecificity of reactions catalyzed by bacterial D-amino acid transaminase.

    PubMed

    Martínez del Pozo, A; Merola, M; Ueno, H; Manning, J M; Tanizawa, K; Nishimura, K; Soda, K; Ringe, D

    1989-10-25

    The spectral shift from 420 to 338 nm when pure bacterial D-amino acid transaminase binds D-amino acid substrates is also exhibited in part by high concentrations of L-amino acids (L-alanine and L-glutamate) but not by simple dicarboxylic acids or monoamines. Slow processing of L-alanine to D-alanine was observed both by coupled enzymatic assays using D-amino acid oxidase and by high pressure liquid chromatography analysis employing an optically active chromophore (Marfey's reagent). When the acceptor for L-alanine was alpha-ketoglutarate, D-glutamate was also formed. This minor activity of the transaminase involved both homologous (L-alanine and D-alanine) and heterologous (L-alanine and D-glutamate) substrate pairs and was a function of the nature of the keto acid acceptor. In the presence of alpha-ketoisovalerate, DL-alanine was almost completely processed to D-valine; within the limits of the assay no L-valine was detected. With alpha-ketoisocaproate, 90% of the DL-alanine was converted to D-leucine. In the mechanism of this transaminase reaction, there may be more stereoselective constraints for the protonation of the quinonoid intermediate during the second half-reaction of the transamination reaction, i.e. the donation of the amino group from the pyridoxamine 5'-phosphate coenzyme to a second keto acid acceptor, than during removal of the alpha proton in the initial steps of the reaction pathway. Thus, with this D-amino acid transaminase, the discrete steps of transamination ensure fidelity of the stereospecificity of reaction pathway. PMID:2808352

  17. Effect of excess levels of lysine and leucine in wheat-based, amino acid-fortified diets on the mRNA expression of two selected cationic amino acid transporters in pigs.

    PubMed

    Morales, A; Barrera, M A; Araiza, A B; Zijlstra, R T; Bernal, H; Cervantes, M

    2013-04-01

    An experiment was conducted to evaluate the effect of excess levels of Leu and Lys on the expression of b(0,+) and CAT-1 mRNA in jejunum, liver and the muscles Longissimus dorsi (LDM) and Semitendinosus (STM). Twenty pigs with an average initial BW of 16.4 ± 1.7 kg were used in a Randomized Complete Block. Dietary treatments (T) were as follows: T1, basal diet; T2, basal plus 3.5 g l-Lys/kg diet; T3, basal plus 1.5 g l-Leu/kg diet; T4, basal plus 3.5 g l-Lys plus 1.5 g l-Leu/kg diet. Diets in T1 and T3 met 100% the requirement of Lys for pigs within the 10 to 20 kg body weight range; diets in T2 and T4 contained 35% excess of Lys. Also, diets in T1 and T2 supplied 104%, whereas diets in T3 and T4 supplied 116% the requirement of Leu. The expression of b(0,+) in jejunum was reduced (p = 0.002) because of the supplementation of l-Leu, but l-Lys supplementation had no effect (p = 0.738). In contrast, the expression of b(0,+) in STM (p = 0.012) and liver (p = 0.095) was reduced by the high level of Lys, but Leu had no effect (p > 0.100). CAT-1 expression in STM increased by high Lys (p = 0.023) and Leu (p = 0.007) levels. In liver, the expression of CAT-1 substantially increased (p = 0.001) because of Lys. In conclusion, excess levels of dietary Lys and Leu affect the expression of cationic amino acid transporters, and this effect varies depending on the studied tissue. PMID:22211733

  18. Child Stunting is Associated with Low Circulating Essential Amino Acids

    PubMed Central

    Semba, Richard D.; Shardell, Michelle; Sakr Ashour, Fayrouz A.; Moaddel, Ruin; Trehan, Indi; Maleta, Kenneth M.; Ordiz, M. Isabel; Kraemer, Klaus; Khadeer, Mohammed A.; Ferrucci, Luigi; Manary, Mark J.

    2016-01-01

    Background Stunting affects about one-quarter of children under five worldwide. The pathogenesis of stunting is poorly understood. Nutritional interventions have had only modest effects in reducing stunting. We hypothesized that insufficiency in essential amino acids may be limiting the linear growth of children. Methods We used a targeted metabolomics approach to measure serum amino acids, glycerophospholipids, sphingolipids, and other metabolites using liquid chromatography-tandem mass spectrometry in 313 children, aged 12–59 months, from rural Malawi. Children underwent anthropometry. Findings Sixty-two percent of the children were stunted. Children with stunting had lower serum concentrations of all nine essential amino acids (tryptophan, isoleucine, leucine, valine, methionine, threonine, histidine, phenylalanine, lysine) compared with nonstunted children (p < 0.01). In addition, stunted children had significantly lower serum concentrations of conditionally essential amino acids (arginine, glycine, glutamine), non-essential amino acids (asparagine, glutamate, serine), and six different sphingolipids compared with nonstunted children. Stunting was also associated with alterations in serum glycerophospholipid concentrations. Interpretation Our findings support the idea that children with a high risk of stunting may not be receiving an adequate dietary intake of essential amino acids and choline, an essential nutrient for the synthesis of sphingolipids and glycerophospholipids. PMID:27211567

  19. Sestrin regulation of TORC1: Is Sestrin a leucine sensor?

    PubMed

    Lee, Jun Hee; Cho, Uhn-Soo; Karin, Michael

    2016-01-01

    Sestrins are highly conserved, stress-inducible proteins that inhibit target of rapamycin complex 1 (TORC1) signaling. After their transcriptional induction, both vertebrate and invertebrate Sestrins turn on the adenosine monophosphate (AMP)-activated protein kinase (AMPK), which activates the tuberous sclerosis complex (TSC), a key inhibitor of TORC1 activation. However, Sestrin overexpression, on occasion, can result in TORC1 inhibition even in AMPK-deficient cells. This effect has been attributed to Sestrin's ability to bind the TORC1-regulating GATOR2 protein complex, which was postulated to control trafficking of TORC1 to lysosomes. How the binding of Sestrins to GATOR2 is regulated and how it contributes to TORC1 inhibition are unknown. New findings suggest that the amino acid leucine specifically disrupts the association of Sestrin2 with GATOR2, thus explaining how leucine and related amino acids stimulate TORC1 activity. We discuss whether and how these findings fit what has already been learned about Sestrin-mediated TORC1 inhibition from genetic studies conducted in fruit flies and mammals. PMID:27273098

  20. Cloning and characterization of brnQ, a gene encoding a low-affinity, branched-chain amino acid carrier in Lactobacillus delbrückii subsp. lactis DSM7290.

    PubMed

    Stucky, K; Hagting, A; Klein, J R; Matern, H; Henrich, B; Konings, W N; Plapp, R

    1995-12-20

    A gene (brnQ), encoding a carrier for branched-chain amino acids in Lactobacillus delbrückii subsp. lactis DSM7290 was cloned in the low-copy-number vector pLG339 by complementation of a transport-deficient Escherichia coli strain. The plasmid carrying the cloned gene restored growth of an E. coli strain mutated in 4 different branched-chain amino acid transport genes at low concentrations of isoleucine, and increased its sensitivity to valine. Transport assays showed that leucine, isoleucine and valine are transported by this carrier and that transport is driven by the proton motive force. Nucleotide sequence analysis revealed an open reading frame of 1338 bp encoding a hydrophobic protein of 446 amino acids with a calculated molecular mass of 47864 Daltons. The start site of brnQ transcription was determined by primer extension analysis using mRNA from Lactobacillus delbrückii subsp. lactis DSM7290. The hydropathy profile suggests the existence of at least 12 hydrophobic domains that probably form membrane-associated alpha-helices. Comparisons of the nucleotide sequence of brnQ from Lactobacillus delbrückii subsp. lactis DSM7290, the amino acid sequence of its product and the topology of the hydrophobic domains with those of the respective carrier genes and proteins of Salmonella typhimurium and Pseudomonas aeruginosa revealed extensive homology. PMID:8544834

  1. 3D Printing of Protein Models in an Undergraduate Laboratory: Leucine Zippers

    ERIC Educational Resources Information Center

    Meyer, Scott C.

    2015-01-01

    An upper-division undergraduate laboratory experiment is described that explores the structure/function relationship of protein domains, namely leucine zippers, through a molecular graphics computer program and physical models fabricated by 3D printing. By generating solvent accessible surfaces and color-coding hydrophobic, basic, and acidic amino…

  2. Selective single crystal complexation of L- or D-leucine by p-sulfonatocalix[6]arene.

    PubMed

    Atwood, Jerry L; Dalgarno, Scott J; Hardie, Michaele J; Raston, Colin L

    2005-01-21

    p-Sulfonatocalix[6]arene, organised in the 'double cone' conformation, has multi-guest capability binding either L- or D-leucine in a single crystal in a bi-layer type arrangement from a racemic mixture of the amino acid. PMID:15645029

  3. FLCN Maintains the Leucine Level in Lysosome to Stimulate mTORC1

    PubMed Central

    Chen, Zhi; Ji, Xin; Qiao, Xianfeng; Jin, Yaping; Liu, Wei

    2016-01-01

    The intracellular amino acid pool within lysosome is a signal that stimulates the nutrient-sensing mTORC1 signalling pathway. The signal transduction cascade has garnered much attention, but little is known about the sequestration of the signalling molecules within the lysosome. Using human HEK293 cells as a model, we found that suppression of the BHD syndrome gene FLCN reduced the leucine level in lysosome, which correlated with decreased mTORC1 activity. Both consequences could be reversed by supplementation with high levels of leucine, but not other tested amino acids. Conversely, overexpressed FLCN could sequester lysosomal leucine and stimulate mTORC1 in an amino acid limitation environment. These results identify a novel function of FLCN: it controls mTORC1 by modulating the leucine signal in lysosome. Furthermore, we provided evidence that FLCN exerted this role by inhibiting the accumulation of the amino acid transporter PAT1 on the lysosome surface, thereby maintaining the signal level within the organelle. PMID:27280402

  4. FLCN Maintains the Leucine Level in Lysosome to Stimulate mTORC1.

    PubMed

    Wu, Xiaochun; Zhao, Lingling; Chen, Zhi; Ji, Xin; Qiao, Xianfeng; Jin, Yaping; Liu, Wei

    2016-01-01

    The intracellular amino acid pool within lysosome is a signal that stimulates the nutrient-sensing mTORC1 signalling pathway. The signal transduction cascade has garnered much attention, but little is known about the sequestration of the signalling molecules within the lysosome. Using human HEK293 cells as a model, we found that suppression of the BHD syndrome gene FLCN reduced the leucine level in lysosome, which correlated with decreased mTORC1 activity. Both consequences could be reversed by supplementation with high levels of leucine, but not other tested amino acids. Conversely, overexpressed FLCN could sequester lysosomal leucine and stimulate mTORC1 in an amino acid limitation environment. These results identify a novel function of FLCN: it controls mTORC1 by modulating the leucine signal in lysosome. Furthermore, we provided evidence that FLCN exerted this role by inhibiting the accumulation of the amino acid transporter PAT1 on the lysosome surface, thereby maintaining the signal level within the organelle. PMID:27280402

  5. Determination of amino acids in Chinese rice wine by fourier transform near-infrared spectroscopy.

    PubMed

    Shen, Fei; Niu, Xiaoying; Yang, Danting; Ying, Yibin; Li, Bobin; Zhu, Geqing; Wu, Jian

    2010-09-01

    Chinese rice wine is abundant in amino acids. The possibility of quantitative detection of 16 free amino acids (aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine, and arginine) in Chinese rice wine by Fourier transform near-infrared (NIR) spectroscopy was investigated for the first time in this study. A total of 98 samples from vintage 2007 rice wines with different aging times were analyzed by NIR spectroscopy in transmission mode. Calibration models were developed using partial least-squares regression (PLSR) with high-performance liquid chromatography (HPLC) by postcolumn derivatization and diode array detection as a reference method. To validate the calibration models, full cross (leave-one-out) validation was employed. The results showed that the calibration statistics were good (rcal>0.94) for all amino acids except proline, histidine, and arginine. The correlation coefficient in cross validation (rcv) was >0.81 for 12 amino acids. The residual predictive deviation (RPD) value obtained was >1.5 in all amino acids except proline and arginine, and it was >2.0 in 6 amino acids. The results obtained in this study indicated that NIR spectroscopy could be used as an easy, rapid, and novel tool to quantitatively predict free amino acids in Chinese rice wine without sophisticated methods. PMID:20707307

  6. 21 CFR 582.5406 - Leucine.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Leucine. 582.5406 Section 582.5406 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

  7. 21 CFR 582.5406 - Leucine.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Leucine. 582.5406 Section 582.5406 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

  8. Elevational Variation in Soil Amino Acid and Inorganic Nitrogen Concentrations in Taibai Mountain, China.

    PubMed

    Cao, Xiaochuang; Ma, Qingxu; Zhong, Chu; Yang, Xin; Zhu, Lianfeng; Zhang, Junhua; Jin, Qianyu; Wu, Lianghuan

    2016-01-01

    Amino acids are important sources of soil organic nitrogen (N), which is essential for plant nutrition, but detailed information about which amino acids predominant and whether amino acid composition varies with elevation is lacking. In this study, we hypothesized that the concentrations of amino acids in soil would increase and their composition would vary along the elevational gradient of Taibai Mountain, as plant-derived organic matter accumulated and N mineralization and microbial immobilization of amino acids slowed with reduced soil temperature. Results showed that the concentrations of soil extractable total N, extractable organic N and amino acids significantly increased with elevation due to the accumulation of soil organic matter and the greater N content. Soil extractable organic N concentration was significantly greater than that of the extractable inorganic N (NO3--N + NH4+-N). On average, soil adsorbed amino acid concentration was approximately 5-fold greater than that of the free amino acids, which indicates that adsorbed amino acids extracted with the strong salt solution likely represent a potential source for the replenishment of free amino acids. We found no appreciable evidence to suggest that amino acids with simple molecular structure were dominant at low elevations, whereas amino acids with high molecular weight and complex aromatic structure dominated the high elevations. Across the elevational gradient, the amino acid pool was dominated by alanine, aspartic acid, glycine, glutamic acid, histidine, serine and threonine. These seven amino acids accounted for approximately 68.9% of the total hydrolyzable amino acid pool. The proportions of isoleucine, tyrosine and methionine varied with elevation, while soil major amino acid composition (including alanine, arginine, aspartic acid, glycine, histidine, leucine, phenylalanine, serine, threonine and valine) did not vary appreciably with elevation (p>0.10). The compositional similarity of many

  9. Elevational Variation in Soil Amino Acid and Inorganic Nitrogen Concentrations in Taibai Mountain, China

    PubMed Central

    Yang, Xin; Zhu, Lianfeng; Zhang, Junhua; Jin, Qianyu; Wu, Lianghuan

    2016-01-01

    Amino acids are important sources of soil organic nitrogen (N), which is essential for plant nutrition, but detailed information about which amino acids predominant and whether amino acid composition varies with elevation is lacking. In this study, we hypothesized that the concentrations of amino acids in soil would increase and their composition would vary along the elevational gradient of Taibai Mountain, as plant-derived organic matter accumulated and N mineralization and microbial immobilization of amino acids slowed with reduced soil temperature. Results showed that the concentrations of soil extractable total N, extractable organic N and amino acids significantly increased with elevation due to the accumulation of soil organic matter and the greater N content. Soil extractable organic N concentration was significantly greater than that of the extractable inorganic N (NO3−-N + NH4+-N). On average, soil adsorbed amino acid concentration was approximately 5-fold greater than that of the free amino acids, which indicates that adsorbed amino acids extracted with the strong salt solution likely represent a potential source for the replenishment of free amino acids. We found no appreciable evidence to suggest that amino acids with simple molecular structure were dominant at low elevations, whereas amino acids with high molecular weight and complex aromatic structure dominated the high elevations. Across the elevational gradient, the amino acid pool was dominated by alanine, aspartic acid, glycine, glutamic acid, histidine, serine and threonine. These seven amino acids accounted for approximately 68.9% of the total hydrolyzable amino acid pool. The proportions of isoleucine, tyrosine and methionine varied with elevation, while soil major amino acid composition (including alanine, arginine, aspartic acid, glycine, histidine, leucine, phenylalanine, serine, threonine and valine) did not vary appreciably with elevation (p>0.10). The compositional similarity of many

  10. Molecular aggregation in selected crystalline 1:1 complexes of hydrophobic D- and L-amino acids. IV. The L-phenylalanine series.

    PubMed

    Görbitz, Carl Henrik; Rissanen, Kari; Valkonen, Arto; Husabø, Asmund

    2009-06-01

    The amino acid L-phenylalanine has been cocrystallized with D-2-aminobutyric acid, C(9)H(11)NO(2).C(4)H(9)NO(2), D-norvaline, C(9)H(11)NO(2).C(5)H(11)NO(2), and D-methionine, C(9)H(11)NO(2).C(5)H(11)NO(2)S, with linear side chains, as well as with D-leucine, C(9)H(11)NO(2).C(6)H(13)NO(2), D-isoleucine, C(9)H(11)NO(2).C(6)H(13)NO(2), and D-allo-isoleucine, C(9)H(11)NO(2).C(6)H(13)NO(2), with branched side chains. The structures of these 1:1 complexes fall into two classes based on the observed hydrogen-bonding pattern. From a comparison with other L:D complexes involving hydrophobic amino acids and regular racemates, it is shown that the structure-directing properties of phenylalanine closely parallel those of valine and isoleucine but not those of leucine, which shares side-chain branching at C(gamma) with phenylalanine and is normally considered to be the most closely related non-aromatic amino acid. PMID:19498234

  11. Leucine Loading Test is Only Discriminative for 3-Methylglutaconic Aciduria Due to AUH Defect.

    PubMed

    Wortmann, Saskia B; Kluijtmans, Leo A J; Sequeira, Silvia; Wevers, Ron A; Morava, Eva

    2014-01-01

    Currently, six inborn errors of metabolism with 3-methylglutaconic aciduria as discriminative feature are known. The "Primary 3-methylglutaconic aciduria," 3-methylglutaconyl-CoA hydratase deficiency or AUH defect, is a disorder of leucine catabolism. For all other subtypes, also denoted "Secondary 3-methylglutaconic acidurias" (TAZ defect or Barth syndrome, SERAC1 defect or MEGDEL syndrome, OPA3 defect or Costeff syndrome, DNAJC19 defect or DCMA syndrome, TMEM70 defect, "not otherwise specified (NOS) 3-MGA-uria"), the origin of 3-methylglutaconic aciduria remains enigmatic but is hypothesized to be independent from leucine catabolism. Here we show the results of leucine loading test in 21 patients with different inborn errors of metabolism who present with 3-methylglutaconic aciduria. After leucine loading urinary 3-methylglutaconic acid levels increased only in the patients with an AUH defect. This strongly supports the hypothesis that 3-methylglutaconic aciduria is independent from leucine breakdown in other inborn errors of metabolism with 3-methylglutaconic aciduria and also provides a simple test to discriminate between primary and secondary 3-methylglutaconic aciduria in regular patient care. PMID:24757000

  12. Differential regulation of protein synthesis in skeletal muscle and liver of neonatal pigs by leucine through an mTORC1-dependent pathway.

    PubMed

    Suryawan, Agus; Nguyen, Hanh V; Almonaci, Rosemarie D; Davis, Teresa A

    2012-02-28

    Neonatal growth is characterized by a high protein synthesis rate that is largely due to an enhanced sensitivity to the postprandial rise in insulin and amino acids, especially leucine. The mechanism of leucine's action in vivo is not well understood. In this study, we investigated the effect of leucine infusion on protein synthesis in skeletal muscle and liver of neonatal pigs. To evaluate the mode of action of leucine, we used rapamycin, an inhibitor of mammalian target of rapamycin (mTOR) complex-1 (mTORC1). Overnight-fasted 7-day-old piglets were treated with rapamycin for 1 hour and then infused with leucine (400 μmol·kg(-1)·h(-1)) for 1 hour. Leucine infusion increased the rate of protein synthesis, and ribosomal protein S6 kinase 1 (S6K1) and eukaryotic initiation factor (eIF) 4E-binding protein-1 (4E-BP1) phosphorylation in gastrocnemius and masseter muscles (P < 0.05), but not in the liver. The leucine-induced stimulation of protein synthesis and S6K1 and 4E-BP1 phosphorylation were completely blocked by rapamycin, suggesting that leucine action is by an mTORC1-dependent mechanism. Neither leucine nor rapamycin had any effect on the activation of the upstream mTORC1 regulators, AMP-activated protein kinase and protein kinase B, in skeletal muscle or liver. The activation of eIF2α and elongation factor 2 was not affected by leucine or rapamycin, indicating that these two pathways are not limiting steps of leucine-induced protein synthesis. These results suggest that leucine stimulates muscle protein synthesis in neonatal pigs by inducing the activation of mTORC1 and its downstream pathway leading to mRNA translation. PMID:22675606

  13. Asymmetric photolysis of /RS/-leucine with circularly polarized ultraviolet light

    NASA Technical Reports Server (NTRS)

    Flores, J. J.; Bonner, W. A.; Massey, G. A.

    1977-01-01

    (RS)-leucine in 0.1 M HCl solution has been subjected to photolysis with 212.8-nm right (R-) and left circularly polarized light (LCPL) obtained from a laser source. RCPL preferentially photolyzed the (R)-leucine component and LCPL the (S)-leucine component of the RS substrate. The enantiomeric excess produced were 1.98% for the 59% conversion with RCPL and 2.50% for the 75% conversion with LCPL. These 'equal and opposite' effects represent the second highest enantiomeric enrichments yet reported for an asymmetric photolysis and the first ever reported for a prebiotically important substrate - an amino acid. Implications regarding the origin of optical activity are briefly discussed.

  14. Incorporation of fucose and leucine into PNS myelin proteins in nerves undergoing early Wallerian degeneration

    SciTech Connect

    Peterson, R.G.; Baughman, S.; Scheidler, D.M.

    1981-02-01

    The simultaneous incorporation of (/sup 3/H)fucose and (1-/sup 14/C)leucine into normal rat sciatic nerve was examined using an in vitro incubation model. A linear rate of protein precursor uptake was found in purified myelin protein over 1/2-6 hr of incubation utilizing a supplemented medium containing amino acids. This model was then used to examine myelin protein synthesis in nerves undergoing degeneration at 1-4 days following a crush injury. Data showed a statistically significant decrease in the ratio of fucose to leucine at 2, 3, and 4 days of degeneration, which was the consequence of a significant increase in leucine uptake. These results, plus substantial protein recovery in axotomized nerves, are indicative of active synthesis of proteins that purify with myelin during early Wallerian degeneration.

  15. Sources of propionate for the biogenesis of ethyl-braced insect juvenile hormones: role of isoleucine and valine

    SciTech Connect

    Brindle, P.A.; Baker, F.C.; Tsai, L.W.; Reuter, C.C.; Schooley, D.A.

    1987-11-01

    Corpora allata from adult female Manduca sexta biosynthesis the sesquiterpenoid juvenile hormone (JH) III and the unusual ethyl-branched homologue JH II in vitro. The authors maintained corpora allata in medium 199 using (methyl-/sup 3/H)methionine as the source of the JH methyl ester moiety and as a mass marker. This allowed measurement of the relative contributions of /sup 14/C-labeled precursors to the biogenesis of JH II and III carbon skeletons. They showed efficient incorporation of a propionate equivalent, from isoleucine or valine catabolism, into the ethyl-branched portion of JH II, using double-label liquid scintillation counting of isolated JHs and gas chromatography/mass spectrometry with selected ion monitoring of JH deuteromethoxyhydrin derivatives. Methionine was a poor source of propionate for JH II biosynthesis, while glucose, succinate, threonine, and ..beta..-alanine did not contribute propionate at all. Leucine, isoleucine, and glucose incorporated into JH III and the acetate-derivative portion of JH II.

  16. Excess leucine intake enhances muscle anabolic signaling but not net protein anabolism in young men and women.

    PubMed

    Glynn, Erin L; Fry, Christopher S; Drummond, Micah J; Timmerman, Kyle L; Dhanani, Shaheen; Volpi, Elena; Rasmussen, Blake B

    2010-11-01

    Essential amino acids (EAA) stimulate skeletal muscle protein synthesis (MPS) in humans. Leucine may have a greater stimulatory effect on MPS than other EAA and/or decrease muscle protein breakdown (MPB). To determine the effect of 2 different leucine concentrations on muscle protein turnover and associated signaling, young men (n = 6) and women (n = 8) ingested 10 g EAA in 1 of 2 groups: composition typical of high quality proteins (CTRL; 1.8 g leucine) or increased leucine concentration (LEU; 3.5 g leucine). Participants were studied for 180 min postingestion. Fractional synthetic rate and leg phenylalanine and leucine kinetics were assessed on muscle biopsies using stable isotopic techniques. Signaling was determined by immunoblotting. Arterial leucine concentration and delivery to the leg increased in both groups and was significantly higher in LEU than in CTRL; however, transport into the muscle and intracellular availability did not differ between groups. MPS increased similarly in both groups 60 min postingestion. MPB decreased at 60 min only in LEU, but net muscle protein balance improved similarly. Components of mammalian target of rapamycin (mTOR) signaling were improved in LEU, but no changes were observed in ubiquitin-proteasome system signaling. Changes in light chain 3 and mTOR association with Unc-51-like kinase 1 indicate autophagy decreased more in LEU. We conclude that in 10 g of EAA, the leucine content typical of high quality proteins (~1.8 g) is sufficient to induce a maximal skeletal muscle protein anabolic response in young adults, but leucine may play a role in autophagy regulation. PMID:20844186

  17. Determination of the D and L isomers of some protein amino acids present in soils

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Cheng, C.-N.; Cronin, S. E.

    1977-01-01

    The D and L isomers of some protein amino acids present in soils were measured by using a gas chromatographic technique. The results of two processing procedures were compared to determine the better method. Results of the comparison indicated that the determination of D and L percentages requires amino acid purification if one is to obtain accurate data. It was found that very significant amounts of D-alanine, D-aspartic acid, and D-glutamic acid were present in the contemporary soils studied. Valine, isoleucine, leucine, proline, and phenylalanine generally contained only a trace to very small amounts of the D isomer. It is probable that the D-amino acids from the alanine, aspartic, and glutamic acids are contributed to the soil primarily via microorganisms. The finding of very significant quantities of some D-amino acids (about 5-16%) in present-day soils may alert some investigators of geological sediments to a possible problem in using amino acid racemization as an age-dating technique.

  18. 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. PMID:19602839

  19. Aspartate protects Lactobacillus casei against acid stress.

    PubMed

    Wu, Chongde; Zhang, Juan; Du, Guocheng; Chen, Jian

    2013-05-01

    The aim of this study was to investigate the effect of aspartate on the acid tolerance of L. casei. Acid stress induced the accumulation of intracellular aspartate in L. casei, and the acid-resistant mutant exhibited 32.5 % higher amount of aspartate than that of the parental strain at pH 4.3. Exogenous aspartate improved the growth performance and acid tolerance of Lactobacillus casei during acid stress. When cultivated in the presence of 50 mM aspartate, the biomass of cells increased 65.8 % compared with the control (without aspartate addition). In addition, cells grown at pH 4.3 with aspartate addition were challenged at pH 3.3 for 3 h, and the survival rate increased 42.26-fold. Analysis of the physiological data showed that the aspartate-supplemented cells exhibited higher intracellular pH (pHi), intracellular NH4 (+) content, H(+)-ATPase activity, and intracellular ATP pool. In addition, higher contents of intermediates involved in glycolysis and tricarboxylic acid cycle were observed in cells in the presence of aspartate. The increased contents of many amino acids including aspartate, arginine, leucine, isoleucine, and valine in aspartate-added cells may contribute to the regulation of pHi. Transcriptional analysis showed that the expression of argG and argH increased during acid stress, and the addition of aspartate induced 1.46- and 3.06-fold higher expressions of argG and argH, respectively, compared with the control. Results presented in this manuscript suggested that aspartate may protect L. casei against acid stress, and it may be used as a potential protectant during the production of probiotics. PMID:23292549

  20. Computational Modeling of the Optical Rotation of Amino Acids: An "in Silico" Experiment for Physical Chemistry

    ERIC Educational Resources Information Center

    Simpson, Scott; Autschbach, Jochen; Zurek, Eva

    2013-01-01

    A computational experiment that investigates the optical activity of the amino acid valine has been developed for an upper-level undergraduate physical chemistry laboratory course. Hybrid density functional theory calculations were carried out for valine to confirm the rule that adding a strong acid to a solution of an amino acid in the l…

  1. Non-ionic surfactant modified ligand exchange chromatography using copper (II) complex of N,N-dimethyl-L-phenylalanine as the chiral additive for enantioselective amino acids separation.

    PubMed

    Dimitrova, Pepa; Bart, Hans-Jörg

    2010-03-17

    The influence of non-ionic surfactants on the selectivity and retention in the ligand exchange chromatography for the enantioselective separation of racemic mixtures of the amino acids dl-methionine, dl-leucine, dl-valine and dl-tyrosine applying chiral mobile phases was investigated, whereas five different surfactants were tested as modifiers. The experiments were carried out using a commercially available non-chiral RP-C8 column and the copper (II) complex of N,N-dimethyl-l-phenylalanine as the chiral additive. Varying the surfactant concentrations the retention factors and the selectivity could be controlled and in general no negative influence on the separation (due to surfactant adsorption on the non-chiral stationary phase) occurred. Changing the temperature the van't Hoff plots were obtained and the thermodynamic parameters calculated. Temperature had influence on the selectivity for each surfactant and lowered the retention times as expected. PMID:20172105

  2. Glycine restores the anabolic response to leucine in a mouse model of acute inflammation.

    PubMed

    Ham, Daniel J; Caldow, Marissa K; Chhen, Victoria; Chee, Annabel; Wang, Xuemin; Proud, Christopher G; Lynch, Gordon S; Koopman, René

    2016-06-01

    Amino acids, especially leucine, potently stimulate protein synthesis and reduce protein breakdown in healthy skeletal muscle and as a result have received considerable attention as potential treatments for muscle wasting. However, the normal anabolic response to amino acids is impaired during muscle-wasting conditions. Although the exact mechanisms of this anabolic resistance are unclear, inflammation and ROS are believed to play a central role. The nonessential amino acid glycine has anti-inflammatory and antioxidant properties and preserves muscle mass in calorie-restricted and tumor-bearing mice. We hypothesized that glycine would restore the normal muscle anabolic response to amino acids under inflammatory conditions. Relative rates of basal and leucine-stimulated protein synthesis were measured using SUnSET methodology 4 h after an injection of 1 mg/kg lipopolysaccharide (LPS). Whereas leucine failed to stimulate muscle protein synthesis in LPS-treated mice pretreated with l-alanine (isonitrogenous control), leucine robustly stimulated protein synthesis (+51%) in mice pretreated with 1 g/kg glycine. The improvement in leucine-stimulated protein synthesis was accompanied by a higher phosphorylation status of mTOR, S6, and 4E-BP1 compared with l-alanine-treated controls. Despite its known anti-inflammatory action in inflammatory cells, glycine did not alter the skeletal muscle inflammatory response to LPS in vivo or in vitro but markedly reduced DHE staining intensity, a marker of oxidative stress, in muscle cross-sections and attenuated LPS-induced wasting in C2C12 myotubes. Our observations in male C57BL/6 mice suggest that glycine may represent a promising nutritional intervention for the attenuation of skeletal muscle wasting. PMID:27094036

  3. Systemic exchangeability of enteral leucine: relationship to plasma flux

    SciTech Connect

    Istfan, N.W.; Ling, P.R.; Bistrian, B.R.; Blackburn, G.L.

    1988-04-01

    The exchangeability of enterally infused leucine within the systemic compartment was estimated in fasted and fed rats using L-(1-/sup 14/C)leucine as a tracer. The experimental design consisted of enteral and parenteral feedings with intravenous or intragastric tracer infusions. During continuous intragastric feeding, only 73 +/- 6% (SE) of the intragastric leucine tracer infusion was accounted for in the systemic circulation. When comparing intravenous vs. intragastric tracer, the estimate of the contribution of protein breakdown to plasma leucine flux was 6 +/- 1 (SE) mumol.h-1.100 g-1 and 18 +/- 3 (SE) mumol.h-1.100 g-1 (P less than 0.01), respectively, for the two routes of administration. Correction of enteral input (either isotope or total leucine), by a factor of 27% for first-pass extraction, eliminated all significant differences in plasma leucine kinetics. Of the 27% of enterally infused tracer not appearing systemically, only 3% could be accounted for in newly synthesized protein in the liver. The remainder is hypothesized to represent first-pass utilization of leucine in intestinal protein synthesis and other metabolic pathways in the splanchnic bed. In contrast, systemic appearance of enteral leucine was essentially complete in the fasted rats, indicating less splanchnic metabolism of leucine in this state. These data indicate that significant error can result in estimating the contribution of endogenous protein breakdown to plasma leucine flux during feeding if the systemic exchangeability of dietary leucine is not considered.

  4. Water Deficit-Induced Changes in Concentrations in Proline and Some Other Amino Acids in the Phloem Sap of Alfalfa.

    PubMed Central

    Girousse, C.; Bournoville, R.; Bonnemain, J. L.

    1996-01-01

    Changes in amino acid composition of alfalfa (Medicago sativa L.) phloem sap were studies in response to a water deficit. Sap was collected by stylectomy. As the leaf water potential ([psi]) decreased from -0.4 to -2.0 MPa, there was significant increase of the total amino acid concentration, due to that of some amino acids: proline, valine, isoleucine, leucine, glutamic acid, aspartic acid, and threonine. Asparagine concentration, which is the main amino acid assayed in the phloem sap of alfalfa (it accounts for 70% of the total content), did not vary with the plant water status. The other amino acid concentrations remained stable as [psi] varied; in particular, [gamma]-amino butyric acid concentration remained unchanged, whereas it varied in response to wounding. The more striking change in the sieve tubes was the accumulation of proline, which was observed below a [psi] threshold value of about -0.9 MPa (concentration x60 for a decrease of [psi] from -0.9 to -2.0 MPa). The role of such changes in phloem sap amino acid concentration in osmotic adjustment of growing tissues is discussed. PMID:12226278

  5. Epithelial cells isolated from chicken jejunum: an experimental model for the study of the functional properties of amino acid transport system b(0,+).

    PubMed

    Angelo, S; Rojas, A M; Ramírez, H; Devés, R

    2002-07-01

    The transport of lysine has been investigated in epithelial cells isolated from chicken jejunum. The kinetics of lysine transport and the pattern of interaction with zwitterionic amino acids were consistent with system b(0,+) activity, the broad-spectrum and Na(+)-independent amino acid transporter. The half-saturation constant for lysine entry (K(m)+/-S.E.) was 0.029+/-0.002 mM and the flux was not affected significantly by Na(+) replacement with choline. Lysine influx was inhibited by L-leucine both in Na(+) and choline medium with inhibition constants (K(i)+/-S.E.) 0.068+/-0.006 mM (in Na(+)) and 0.065+/-0.009 mM (in choline). Other inhibitory amino acids (K(i)+/-S.E.) were (mM): L-tyrosine (0.073+/-0.018), L-methionine (0.15+/-0.015), L-cystine (0.42+/-0.04), L-cysteine (1.1+/-0.07), L-isoleucine (1.1+/-0.09), L-glutamine (1.8+/-0.16) and L-valine (2.5+/-0.13). Lysine exit was trans-accelerated (approx. 20 fold) by 2 mM L-lysine and L-leucine. The flux was resistant to pretreatment of the cells with p-chloromercuriphenylsulfonate (0.2 mM), which is an inhibitor of system y(+)L, the broad-spectrum and cation-modulated transporter. PMID:12044773

  6. The effects of short intensive exercise on plasma free amino acids in standardbred trotters.

    PubMed

    Hackl, S; van den Hoven, R; Zickl, M; Spona, J; Zentek, J

    2009-04-01

    The aim of this study was to investigate the effect of short intense exercise on plasma amino acid concentrations in trotters and to test the repeatability of plasma amino acids concentration in samples obtained on two independent days under field conditions. Plasma amino acid concentrations were analysed in blood samples of 36 standardbred trotters before and after intense exercise over a distance of 2000 m. Sampling was repeated in 20 horses after 35 days. Exercise intensity was estimated from post-exercise lactate levels. Horses were divided in two groups according to a cut-off lactate concentration at 15 mmol/l. The plasma concentrations of alanine, aspartate, glutamate, isoleucine, leucine, lysine and taurine increased and arginine, asparagine, citrulline, glutamine, glycine, histidine, methionine, serine, tryptophan and 3-methylhistidine decreased after exercise. Ornithine, threonine, tyrosine, phenylalanine and valine concentrations remained constant. Higher intensity of exercise significantly decreased tryptophan and increased taurine concentrations. Sampling day had a significant effect on the absolute pre- and post-exercise amino acid concentrations. Exercise had a significant influence on the concentrations of most plasma amino acids in trotters. These changes could reflect shifts between the free amino acid compartments, but there were also some indications for muscle catabolism. The amino acid supply of sporting horses could be of specific significance for maintaining muscle integrity and for the improvement of post-exercise recovery of competition horses. PMID:19320929

  7. Biological activities of indoleacetylamino acids and their use as auxins in tissue culture

    SciTech Connect

    Hangarter, R.P.; Peterson, M.D.; Good, N.E.

    1980-05-01

    The auxin activities of a number of indoleacetylamino acid conjugates have been determined in three test systems: growth of tomato hypocotyl explants (Lycopersicon esculentum Mill. cv. Marglobe); growth of tobacco callus cultures (Nicotiana tabacum L. cv. Wisconsin 38); and ethylene production from pea stems (Pisum sativum L. cv. Alaska). The activities of the conjugates differ greatly depending on the amino acid moiety. Indoleacetyl-L-alanine supports rapid callus growth from the tomato hypocotyls while inhibiting growth of shoots and roots. Indoleacetlyglycine behaves in a similar manner but is somewhat less effective in supporting callus growth and in inhibiting growth of shoots and roots. Indoleacetylglycine behaves in a similar manner but is somewhat less effective in supporting callus growth and in inhibiting shoot formation. The other amino acid conjugates tested (valine, leucine, aspartic acid, threonine, methionine, phenylalanine, and proline) support shoot formation without supporting root formation or much callus growth. The tobacco callus system, which forms abundant shoots in the presence or absence of free indoleacetic acid, produces only rapid undifferentiated growth in the presence of indoleacetyl-L-alanine and indoleacetylglycine. The other conjugates inhibit shoot formatin weakly if at all. Most of the conjugates induce sustained ethylene production from the pea stems but at rates well below the initial rates observed with free indoleacetic acid. Many, but not all of the effects of conjugates such as indoleacetyl-L-alanine can be mimicked by frequent renewals of the supply of free indoleacetic acid.

  8. A Single Valine Residue Plays an Essential Role in Peripherin/rds Targeting to Photoreceptor Outer Segments

    PubMed Central

    Salinas, Raquel Y.; Baker, Sheila A.; Gospe, Sidney M.; Arshavsky, Vadim Y.

    2013-01-01

    Peripherin/retinal degeneration slow (rds) is an integral membrane protein specifically localized to the light-sensing organelle of the photoreceptor cell, the outer segment. Within the outer segment, peripherin is found at the edges of photoreceptor discs, where it plays a critical role in disc morphogenesis and maintenance. Peripherin loss or mutations are often associated with severe forms of visual impairments. Like all other resident outer segment proteins, peripherin is synthesized in the photoreceptor cell body and subsequently transported to the outer segment. In an effort to further examine peripherin’s delivery to outer segments, we undertook a careful examination of its targeting sequence. Using a fluorescently labeled reporter expressed in the rods of transgenic tadpoles, we narrowed peripherin’s targeting sequence to ten amino acids within its C-terminal tail. This small stretch of amino acid residues is both necessary and sufficient for outer segment targeting. We also conducted alanine scanning of all residues within this sequence and found that only a single residue, valine at position 332, is essential for outer segment targeting. This valine is conserved in all species and its mutation is sufficient to completely abrogate the targeting of full-length peripherin in mouse rods. PMID:23342122

  9. Enthalpy pair coefficients of interaction for DL-valine in aqueous solutions of polyatomic alcohols at 298 K

    NASA Astrophysics Data System (ADS)

    Mezhevoi, I. N.; Badelin, V. G.

    2013-12-01

    Integral enthalpies of dissolution Δsol H m of DL-valine are measured via calorimetry of dissolution in aqueous solutions of glycerol, ethylene glycol, and 1,2-propylene glycol. Standard values of the enthalpies of dissolution (Δsol H ○) and transfer (Δtr H ○) of amino acid from water to mixed solvent are calculated from the resulting experimental data. The enthalpy coefficients for pair interactions hxy of amino acid with polyatomic alcohol molecules are calculated using the McMillan-Meyer theory and have positive values. The obtained results are discussed in light of the theory of the predomination of various types of interactions in mixed solutions and the effect of structural features of interacting biomolecules on the thermochemical parameters of the dissolution of amino acids.

  10. Plasma arginine and leucine kinetics and urea production rates in burn patients.

    PubMed

    Yu, Y M; Young, V R; Castillo, L; Chapman, T E; Tompkins, R G; Ryan, C M; Burke, J F

    1995-05-01

    We measured plasma arginine and leucine kinetics and rates of urea production (appearance) in 12 severely burned patients (mean body surface burn area, 48%) during a basal state (low-dose intravenous glucose) and while receiving routine, total parenteral nutrition ([TPN] fed state) including an L-amino acid mixture, supplying a generous level of nitrogen (mean, 0.36 g N.kg-1.d-1). The two nutritional states were studied in random order using a primed 4-hour constant intravenous tracer infusion protocol. Stable-nuclide-labeled tracers were L-[guanidino-13C]arginine, L-[1-13C]leucine, [18O]urea, and NaH13CO3 (prime only), with blood and expired air samples drawn at intervals to determine isotopic abundance of arginine, citrulline, ornithine, alpha-ketoisocaproate ([KIC] for leucine), and urea in plasma and 13CO2 in breath. Results are compared with data obtained in these laboratories in healthy adults. Leucine kinetics (flux and disappearance into protein synthesis) indicated the expected higher turnover in burn patients than in healthy controls. Mean leucine oxidation rates are also higher and compared well with values predicted from urea production rates, provided that urea nitrogen recycling via intestinal hydrolysis is taken into account. The plasma urea flux was also higher than for normal subjects. Arginine fluxes as measured in the systemic whole body, via the plasma pool, were correspondingly higher in burned patients than in healthy controls and were in good agreement with values predicted from leucine-KIC kinetics. However, systemic whole-body arginine flux measured via the plasma pool was only 20% of the arginine flux estimated from the urea flux plus the rate of protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7752916

  11. Polarized Raman spectra and intensities of aliphatic amino acids

    NASA Astrophysics Data System (ADS)

    Himmler, Hans J.; Eysel, Hans H.

    1989-01-01

    Raman spectra of aliphatic α- L-amino acids, glycine, alanine, and valine were re-investigated both in aqueous solution and deuterium oxide solution. The spectra were taken of the zwitterionic and of the completely deprotonated form of the amino acids. Spectra of leucine and isoleucine were studied in water at the isoelectric point. Spectra were recorded both with parallel and perpendicular polarization and the isotropic and anisotropic scattering components were isolated. The integrated intensities of CH stretch, CC stretch and carboxylate bend vibrations are discussed. Linear relations between the number of CC and CH bonds and the total scattered intensity in the appropriate spectral regions are observed. The sum over the carboxylate modes shows characteristic intensities for the first three members of the aliphatic amino acids. An increase of isotropic scattering of ϱ co 2 near 510 cm -1 with increasing chain length of the amino acid (or with increasing concentration) is interpreted as the result of micelle formation.

  12. Branched-Chain Amino Acid Metabolism in Arabidopsis thaliana

    PubMed Central

    Binder, Stefan

    2010-01-01

    Valine, leucine and isoleucine form the small group of branched-chain amino acids (BCAAs) classified by their small branched hydrocarbon residues. Unlike animals, plants are able to de novo synthesize these amino acids from pyruvate, 2-oxobutanoate and acetyl-CoA. In plants, biosynthesis follows the typical reaction pathways established for the formation of these amino acids in microorganisms. Val and Ile are synthesized in two parallel pathways using a single set of enzymes. The pathway to Leu branches of from the final intermediate of Val biosynthesis. The formation of this amino acid requires a three-step pathway generating a 2-oxoacid elongated by a methylene group. In Arabidopsis thaliana and other Brassicaceae, a homologous three-step pathway is also involved in Met chain elongation required for the biosynthesis of aliphatic glucosinolates, an important class of specialized metabolites in Brassicaceae. This is a prime example for the evolutionary relationship of pathways from primary and specialized metabolism. Similar to animals, plants also have the ability to degrade BCAAs. The importance of BCAA turnover has long been unclear, but now it seems apparent that the breakdown process might by relevant under certain environmental conditions. In this review, I summarize the current knowledge about BCAA metabolism, its regulation and its particular features in Arabidopsis thaliana. PMID:22303262

  13. A study of L-leucine, L-phenylalanine and L-alanine transport in the perfused rat mammary gland: possible involvement of LAT1 and LAT2.

    PubMed

    Shennan, D B; Calvert, D T; Travers, M T; Kudo, Y; Boyd, C A R

    2002-08-19

    The transport of L-leucine, L-phenylalanine and L-alanine by the perfused lactating rat mammary gland has been examined using a rapid, paired-tracer dilution technique. The clearances of all three amino acids by the mammary gland consisted of a rising phase followed by a rapid fall-off, respectively, reflecting influx and efflux of the radiotracers. The peak clearance of L-leucine was inhibited by BCH (65%) and D-leucine (58%) but not by L-proline. The inhibition of L-leucine clearance by BCH and D-leucine was not additive. L-leucine inhibited the peak clearance of radiolabelled L-leucine by 78%. BCH also inhibited the peak clearance of L-phenylalanine (66%) and L-alanine (33%) by the perfused mammary gland. Lactating rat mammary tissue was found to express both LAT1 and LAT2 mRNA. The results suggest that system L is situated in the basolateral aspect of the lactating rat mammary epithelium and thus probably plays a central role in neutral amino acid uptake from blood. The finding that L-alanine uptake by the gland was inhibited by BCH suggests that LAT2 may make a significant contribution to neutral amino acid uptake by the mammary epithelium. PMID:12101005

  14. L-leucine, beta-hydroxy-beta-methylbutyric acid (HMB) and creatine monohydrate prevent myostatin-induced Akirin-1/Mighty mRNA down-regulation and myotube atrophy

    PubMed Central

    2014-01-01

    Background The purpose of this study was to examine if L-leucine (Leu), β-hydroxy-β-methylbutyrate (HMB), or creatine monohydrate (Crea) prevented potential atrophic effects of myostatin (MSTN) on differentiated C2C12 myotubes. Methods After four days of differentiation, myotubes were treated with MSTN (10 ng/ml) for two additional days and four treatment groups were studied: 1) 3x per day 10 mM Leu, 2) 3x per day 10 mM HMB, 3) 3x per day 10 mM Crea, 4) DM only. Myotubes treated with DM without MSTN were analyzed as the control condition (DM/CTL). Following treatment, cells were analyzed for total protein, DNA content, RNA content, muscle protein synthesis (MPS, SUnSET method), and fiber diameter. Separate batch treatments were analyzed for mRNA expression patterns of myostatin-related genes (Akirin-1/Mighty, Notch-1, Ski, MyoD) as well as atrogenes (MuRF-1, and MAFbx/Atrogin-1). Results MSTN decreased fiber diameter approximately 30% compared to DM/CTL myotubes (p < 0.001). Leu, HMB and Crea prevented MSTN-induced atrophy. MSTN did not decrease MPS levels compared to DM/CTL myotubes, but MSTN treatment decreased the mRNA expression of Akirin-1/Mighty by 27% (p < 0.001) and MyoD by 26% (p < 0.01) compared to DM/CTL myotubes. shRNA experiments confirmed that Mighty mRNA knockdown reduced myotube size, linking MSTN treatment to atrophy independent of MPS. Remarkably, MSTN + Leu and MSTN + HMB myotubes had similar Akirin-1/Mighty and MyoD mRNA levels compared to DM/CTL myotubes. Furthermore, MSTN + Crea myotubes exhibited a 36% (p < 0.05) and 86% (p < 0.001) increase in Akirin-1/Mighty mRNA compared to DM/CTL and MSTN-only treated myotubes, respectively. Conclusions Leu, HMB and Crea may reduce MSTN-induced muscle fiber atrophy by influencing Akirin-1/Mighty mRNA expression patterns. Future studies are needed to examine if Leu, HMB and Crea independently or synergistically affect Akirin-1/Mighty expression, and how Akirin-1/Mighty

  15. Hypertrophy-Promoting Effects of Leucine Supplementation and Moderate Intensity Aerobic Exercise in Pre-Senescent Mice

    PubMed Central

    Xia, Zhi; Cholewa, Jason; Zhao, Yan; Yang, Yue-Qin; Shang, Hua-Yu; Guimarães-Ferreira, Lucas; Naimo, Marshall Alan; Su, Quan-Sheng; Zanchi, Nelo Eidy

    2016-01-01

    Several studies have indicated a positive influence of leucine supplementation and aerobic training on the aging skeletal muscle signaling pathways that control muscle protein balance and muscle remodeling. However, the effect of a combined intervention requires further clarification. Thirteen month old CD-1® mice were subjected to moderate aerobic exercise (45 min swimming per day with 3% body weight workload) and fed a chow diet with 5% leucine or 3.4% alanine for 8 weeks. Serum and plasma were prepared for glucose, urea nitrogen, insulin and amino acid profile analysis. The white gastrocnemius muscles were used for determination of muscle size and signaling proteins involved in protein synthesis and degradation. The results show that both 8 weeks of leucine supplementation and aerobic training elevated the activity of mTOR (mammalian target of rapamycin) and its downstream target p70S6K and 4E-BP1, inhibited the ubiquitin-proteasome system, and increased fiber cross-sectional area (CSA) in white gastrocnemius muscle. Moreover, leucine supplementation in combination with exercise demonstrated more significant effects, such as greater CSA, protein content and altered phosphorylation (suggestive of increased activity) of protein synthesis signaling proteins, in addition to lower expression of proteins involved in protein degradation compared to leucine or exercise alone. The current study shows moderate aerobic training combined with 5% leucine supplementation has the potential to increase muscle size in fast-twitch skeletal muscle during aging, potentially through increased protein synthesis and decreased protein breakdown. PMID:27144582

  16. Hypertrophy-Promoting Effects of Leucine Supplementation and Moderate Intensity Aerobic Exercise in Pre-Senescent Mice.

    PubMed

    Xia, Zhi; Cholewa, Jason; Zhao, Yan; Yang, Yue-Qin; Shang, Hua-Yu; Guimarães-Ferreira, Lucas; Naimo, Marshall Alan; Su, Quan-Sheng; Zanchi, Nelo Eidy

    2016-01-01

    Several studies have indicated a positive influence of leucine supplementation and aerobic training on the aging skeletal muscle signaling pathways that control muscle protein balance and muscle remodeling. However, the effect of a combined intervention requires further clarification. Thirteen month old CD-1(®) mice were subjected to moderate aerobic exercise (45 min swimming per day with 3% body weight workload) and fed a chow diet with 5% leucine or 3.4% alanine for 8 weeks. Serum and plasma were prepared for glucose, urea nitrogen, insulin and amino acid profile analysis. The white gastrocnemius muscles were used for determination of muscle size and signaling proteins involved in protein synthesis and degradation. The results show that both 8 weeks of leucine supplementation and aerobic training elevated the activity of mTOR (mammalian target of rapamycin) and its downstream target p70S6K and 4E-BP1, inhibited the ubiquitin-proteasome system, and increased fiber cross-sectional area (CSA) in white gastrocnemius muscle. Moreover, leucine supplementation in combination with exercise demonstrated more significant effects, such as greater CSA, protein content and altered phosphorylation (suggestive of increased activity) of protein synthesis signaling proteins, in addition to lower expression of proteins involved in protein degradation compared to leucine or exercise alone. The current study shows moderate aerobic training combined with 5% leucine supplementation has the potential to increase muscle size in fast-twitch skeletal muscle during aging, potentially through increased protein synthesis and decreased protein breakdown. PMID:27144582

  17. Skeletal muscle protein synthesis in neonatal pigs is stimulated by A-ketoisocaproic acid, but not by norleucine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In neonatal pigs, skeletal muscle protein synthesis is stimulated when plasma leucine is increased within the physiological postprandial range. We previously have shown that valine and isoleucine were not able to stimulate protein synthesis when their plasma concentrations were elevated within the ...

  18. Investigations on particle surface characteristics vs. dispersion behaviour of L-leucine coated carrier-free inhalable powders.

    PubMed

    Raula, Janne; Thielmann, Frank; Naderi, Majid; Lehto, Vesa-Pekka; Kauppinen, Esko I

    2010-01-29

    Aerosol microparticles of salbutamol sulphate are gas-phase coated with an amino acid L-leucine. Depending of the saturated state of L-leucine, the coating is formed by the surface diffusion of L-leucine molecules within a droplet or by the physical vapour deposition (PVD) of L-leucine or by the combination thereof. The PVD coated particles showed excellent aerosolization characteristics in a carrier-free powder delivery from an inhaler. The aerosolization of the fine powders is compared with surface energy parameters analysed by inverse gas chromatography (IGC). The dispersion testing is conducted by a Inhalation Simulator using a fast inhalation profile with inhalation flow rate of 67 l min(-1). It is found that the powder emission is affected by the morphology, surface roughness (asperity size and density) of the particles and acidity of particle surface. The latter affects the dispersion and dose repeatability of fine powder in a case if L-leucine content is high enough. However, there is no direct correlation between dispersive surface energies and aerosolization performances of the powders. Crucial factors for the improved aerosolization rely weakly on surface acid-base properties but strongly on particle morphology and fine-scale surface roughness. PMID:19879344

  19. Designed heterodimerizing leucine zippers with a ranger of pIs and stabilities up to 10(-15) M.

    PubMed

    Moll, J R; Ruvinov, S B; Pastan, I; Vinson, C

    2001-03-01

    We have designed a heterodimerizing leucine zipper system to target a radionuclide to prelocalized noninternalizing tumor-specific antibodies. The modular nature of the leucine zipper allows us to iteratively use design rules to achieve specific homodimer and heterodimer affinities. We present circular-dichroism thermal denaturation measurements on four pairs of heterodimerizing leucine zippers. These peptides are 47 amino acids long and contain four or five pairs of electrostatically attractive g <--> e' (i, i' +5) interhelical heterodimeric interactions. The most stable heterodimer consists of an acidic leucine zipper and a basic leucine zipper that melt as homodimers in the micro (T(m) = 28 degrees C) or nanomolar (T(m) = 40 degrees C) range, respectively, but heterodimerize with a T(m) >90 degrees C, calculated to represent femtamolar affinities. Modifications to this pair of acidic and basic zippers, designed to destabilize homodimerization, resulted in peptides that are unstructured monomers at 4 microM and 6 degrees C but that heterodimerize with a T(m) = 74 degrees C or K(d(37)) = 1.1 x 10(-11) M. A third heterodimerizing pair was designed to have a more neutral isoelectric focusing point (pI) and formed a heterodimer with T(m) = 73 degrees C. We can tailor this heterodimerizing system to achieve pharmacokinetics aimed at optimizing targeted killing of cancer cells. PMID:11344333

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

    PubMed

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

    2007-03-22

    The potentials of mean force of homodimers of the molecules modeling hydrophobic amino acid side chains (ethane (for alanine), propane (for proline), isobutane (for valine), isopentane (for leucine and isoleucine), ethylbenzene (for phenylalanine), and methyl propyl sulfide (for methionine)) were determined by umbrella-sampling molecular dynamics simulations in explicit water as functions of distance and orientation. Analytical expressions consisting of the Gay-Berne term to represent effective van der Waals interactions and the cavity term derived in paper 1 of this series were fitted to the potentials of mean force. The positions and depths of the contact minima and the positions and heights of the desolvation maxima, including their dependence on the orientation of the molecules, were well represented by the analytical expressions for all systems, which justifies use of such potentials in coarse-grain protein-folding simulations. PMID:17388418

  1. Search for conserved amino acid residues of the [Formula: see text]-crystallin proteins of vertebrates.

    PubMed

    Shiliaev, Nikita G; Selivanova, Olga M; Galzitskaya, Oxana V

    2016-04-01

    [Formula: see text]-crystallin is the major eye lens protein and a member of the small heat-shock protein (sHsp) family. [Formula: see text]-crystallins have been shown to support lens clarity by preventing the aggregation of lens proteins. We performed the bioinformatics analysis of [Formula: see text]-crystallin sequences from vertebrates to find conserved amino acid residues as the three-dimensional (3D) structure of [Formula: see text]-crystallin is not identified yet. We are the first who demonstrated that the N-terminal region is conservative along with the central domain for vertebrate organisms. We have found that there is correlation between the conserved and structured regions. Moreover, amyloidogenic regions also correspond to the structured regions. We analyzed the amino acid composition of [Formula: see text]-crystallin A and B chains. Analyzing the occurrence of each individual amino acid residue, we have found that such amino acid residues as leucine, serine, lysine, proline, phenylalanine, histidine, isoleucine, glutamic acid, and valine change their content simultaneously in A and B chains in different classes of vertebrates. Aromatic amino acids occur more often in [Formula: see text]-crystallins from vertebrates than on the average in proteins among 17 animal proteomes. We obtained that the identity between A and B chains in the mammalian group is 0.35, which is lower than the published 0.60. PMID:26972563

  2. A study of conformational stability of poly(L-alanine), poly(L-valine), and poly(L-alanine)/poly(L-valine) blends in the solid state by (13)C cross-polarization/magic angle spinning NMR.

    PubMed

    Murata, Katsuyoshi; Kuroki, Shigeki; Kimura, Hideaki; Ando, Isao

    2002-06-01

    13C cross-polarization/magic angle spinning (CP/MAS) NMR and (1)H T(1rho) experiments of poly(L-alanine) (PLA), poly(L-valine) (PLV), and PLA/PLV blends have been carried out in order to elucidate the conformational stability of the polypeptides in the solid state. These were prepared by adding a trifluoroacetic acid (TFA) solution of the polymer with a 2.0 wt/wt % of sulfuric acid (H(2)SO(4)) to alkaline water. From these experimental results, it is clarified that the conformations of PLA and PLV in their blends are strongly influenced by intermolecular hydrogen-bonding interactions that cause their miscibility at the molecular level. PMID:11948439

  3. Cloning and nucleotide sequences of livB and livC, the structural genes encoding binding proteins of the high-affinity branched-chain amino acid transport in Salmonella typhimurium.

    PubMed

    Ohnishi, K; Nakazima, A; Matsubara, K; Kiritani, K

    1990-02-01

    The liv gene cluster responsible for encoding the high-affinity branched-chain amino acid transport proteins in Salmonella typhimurium was mapped in the 7.6-kilobase HindIII-SacI segment of plasmid pMN12 by utilizing the gene dosage effect. By subcloning and biochemical analysis, the livB and livC structural genes encoding the leucine-, isoleucine-, valine-, threonine-binding protein (LIVT-BP) and the leucine-specific binding protein (L-BP), respectively, were localized within the 3,617-base HindIII-BstEII segment. Upon determining the nucleotide sequence of the 3,617 bases, we found that the coding sequence of the livB gene (1,095 base pairs) starts at the position 355 and specifies the precursor LIVT-BP of 365 amino acid residues, and the livC gene (1,107 base pairs) starts at the position 2,452 and encodes the precursor L-BP of 369 amino acid residues. The two genes, separated by a 1-kilobase intergenic region, each possess potential promoters and rho-independent transcriptional terminators. The mature LIVT-BP and L-BP are produced by removing the putative 21 and 23 signal peptides from the respective precursors. In comparison with the analogous two binding proteins from Escherichia coli K-12, strong homologies are observed. PMID:2193932

  4. Serine- and threonine/valine-dependent activation of PDK and Tor orthologs converge on Sch9 to promote aging.

    PubMed

    Mirisola, Mario G; Taormina, Giusi; Fabrizio, Paola; Wei, Min; Hu, Jia; Longo, Valter D

    2014-02-01

    Dietary restriction extends longevity in organisms ranging from bacteria to mice and protects primates from a variety of diseases, but the contribution of each dietary component to aging is poorly understood. Here we demonstrate that glucose and specific amino acids promote stress sensitization and aging through the differential activation of the Ras/cAMP/PKA, PKH1/2 and Tor/S6K pathways. Whereas glucose sensitized cells through a Ras-dependent mechanism, threonine and valine promoted cellular sensitization and aging primarily by activating the Tor/S6K pathway and serine promoted sensitization via PDK1 orthologs Pkh1/2. Serine, threonine and valine activated a signaling network in which Sch9 integrates TORC1 and Pkh signaling via phosphorylation of threonines 570 and 737 and promoted intracellular relocalization and transcriptional inhibition of the stress resistance protein kinase Rim15. Because of the conserved pro-aging role of nutrient and growth signaling pathways in higher eukaryotes, these results raise the possibility that similar mechanisms contribute to aging in mammals. PMID:24516402

  5. Serine- and Threonine/Valine-Dependent Activation of PDK and Tor Orthologs Converge on Sch9 to Promote Aging

    PubMed Central

    Fabrizio, Paola; Wei, Min; Hu, Jia; Longo, Valter D.

    2014-01-01

    Dietary restriction extends longevity in organisms ranging from bacteria to mice and protects primates from a variety of diseases, but the contribution of each dietary component to aging is poorly understood. Here we demonstrate that glucose and specific amino acids promote stress sensitization and aging through the differential activation of the Ras/cAMP/PKA, PKH1/2 and Tor/S6K pathways. Whereas glucose sensitized cells through a Ras-dependent mechanism, threonine and valine promoted cellular sensitization and aging primarily by activating the Tor/S6K pathway and serine promoted sensitization via PDK1 orthologs Pkh1/2. Serine, threonine and valine activated a signaling network in which Sch9 integrates TORC1 and Pkh signaling via phosphorylation of threonines 570 and 737 and promoted intracellular relocalization and transcriptional inhibition of the stress resistance protein kinase Rim15. Because of the conserved pro-aging role of nutrient and growth signaling pathways in higher eukaryotes, these results raise the possibility that similar mechanisms contribute to aging in mammals. PMID:24516402

  6. Intermolecular Vibrations of Hydrophobic Amino Acids

    NASA Astrophysics Data System (ADS)

    Williams, Michael Roy Casselman

    -TDS) was used to measure the absorption spectra of low-frequency vibrational modes for a variety of hydrophobic amino acids in the solid (polycrystalline) state. The THz-TDS technique uses ultrafast (<50 fs) pulses of light from a visible/near-IR laser to generate single-cycle pulses of THz (far-IR) light. Pulses from the ultrafast laser are also used to coherently gate a THz detector, allowing phase-sensitive measurements of the THz electric field. In some cases, Raman scattering spectra of some of the polycrystalline hydrophobic amino acid samples were measured as well, in this case using an Ar+ laser and a triple monochromator to detect signals at the low Raman-shift values corresponding to the far-IR. THz-TDS was used to measure the low-frequency vibrational absorption spectra of pure L- and pure D-valine crystals as well as the racemic cocrystal, DL-valine. As expected, the Land D-valine THz-TDS absorption spectra are identical to one another (they are enantiomorphous crystals) but very different from the spectrum of DL-valine. In the process of these experiments, it was discovered that it was possible to prepare two distinct polymorphs (different crystalline arrangements) of DL-valine by varying the conditions under which stock material was recrystallized. Once crystallized in a particular form, both polymorphs remained (meta)stable at all temperatures investigated (from 80 K to room temperature), i.e., no phase transformation was observed. The THz-TDS and Raman spectra of the two polymorphs of DL-valine were measured. In addition, THz-TDS and Raman spectra of DL-leucine were measured; this substance has a crystal structure closely analagous to one of the DL-valine polymorphs. The temperature-dependence of the THz-TDS spectrum of each material was also measured. At lower temperatures, it is generally expected that intermolecular vibration frequencies increase (blueshift) due to a shrinking unit cell (effectively squeezing the oscillator potential into a smaller space

  7. Investigations on the effect of amino acids on acrylamide, pyrazines, and Michael addition products in model systems.

    PubMed

    Koutsidis, Georgios; Simons, Sandra P J; Thong, Yeong H; Haldoupis, Yannis; Mojica-Lazaro, Jonas; Wedzicha, Bronislaw L; Mottram, Donald S

    2009-10-14

    Acrylamide and pyrazine formation, as influenced by the incorporation of different amino acids, was investigated in sealed low-moisture asparagine-glucose model systems. Added amino acids, with the exception of glycine and cysteine and at an equimolar concentration to asparagine, increased the rate of acrylamide formation. The strong correlation between the unsubstituted pyrazine and acrylamide suggests the promotion of the formation of Maillard reaction intermediates, and in particular glyoxal, as the determining mode of action. At increased amino acid concentrations, diverse effects were observed. The initial rates of acrylamide formation remained high for valine, alanine, phenylalanine, tryptophan, glutamine, and leucine, while a significant mitigating effect, as evident from the acrylamide yields after 60 min of heating at 160 degrees C, was observed for proline, tryptophan, glycine, and cysteine. The secondary amine containing amino acids, proline and tryptophan, had the most profound mitigating effect on acrylamide after 60 min of heating. The relative importance of the competing effect of added amino acids for alpha-dicarbonyls and acrylamide-amino acid alkylation reactions is discussed and accompanied by data on the relative formation rates of selected amino acid-AA adducts. PMID:19739658

  8. Changes in total nitrogen and amino acid composition of New Zealand Undaria pinnatifida with growth, location and plant parts.

    PubMed

    Zhou, April Yongdong; Robertson, John; Hamid, Nazimah; Ma, Qianli; Lu, Jun

    2015-11-01

    Undaria pinnatifida is known as unwanted organism in New Zealand. However, Wakame is a traditional food made of U. pinnatifida, which is now cultured extensively in East Asia. Therefore, it is important to examine this introduced alga as a potential source of dietary protein for human consumption in New Zealand. This study determined total nitrogen content and amino acid profile of New Zealand U. pinnatifida harvested from the Marlborough Sounds on a monthly basis from June to November 2011. Total average nitrogen content and crude protein content was 21.02 mg/g dry weight and 13.1% of dry weight, respectively. The three most abundant amino acids that contributed to flavour (glutamic acid, aspartic acid and alanine) were present and the most abundant essential amino acids were arginine, leucine, lysine and valine. The results showed that the amino acid content in blades from the exposed farm was significantly higher (P < 0.05) than the others. Sporophyll maturation of U. pinnatifida in New Zealand influenced protein content and amino acid composition. Sporophyll, considered as a waste product by many, was found to be a potentially good source of protein. PMID:25976828

  9. Leucine: tRNA Ligase from Cultured Cells of Nicotiana tabacum var. Xanthi

    PubMed Central

    Gore, Nigel R.; Wray, John L.

    1978-01-01

    Leucine:tRNA ligase was assayed in extracts from cultured tobacco (Nicotiana tabacum) XD cells by measuring the initial rate of aminoacylation of transfer RNA with l-[4,5-3H]leucine. Transfer RNA was purified from tobacco XD cells after the method of Vanderhoef et al. (Phytochemistry 9: 2291-2304). The buoyant density of leucine:tRNA ligase from cells grown for 100 generations in 2.5 mm [15N]nitrate and 30% deuterium oxide was 1.3397. After transfer of cells into light medium (2.5 mm [14N]nitrate and 100% H2O) the ligase activity increased and the buoyant density decreased with time to 1.3174 at 72 hours after transfer. It was concluded that leucine:tRNA ligase molecules were synthesized de novo from light amino acids during the period of activity increase. The width at half-peak height of the enzyme distribution profiles following isopycnic equilibrium centrifugation in caesium chloride remained constant at all times after transfer into light medium providing evidence for the loss of preexisting functional ligase molecules. It was concluded that during the period of activity increase the cellular level of enzyme activity was determined by a balance between de novo synthesis and the loss of functional enzyme molecules due to either inactivation or degradation. PMID:16660229

  10. Autophagy and leucine promote chronological longevity and respiration proficiency during calorie restriction in yeast

    PubMed Central

    Aris, John P.; Alvers, Ashley L.; Ferraiuolo, Roy A.; Fishwick, Laura K.; Hanvivatpong, Amanda; Hu, Doreen; Kirlew, Christine; Leonard, Michael T.; Losin, Kyle J.; Marraffini, Michelle; Seo, Arnold Y.; Swanberg, Veronica; Westcott, Jennifer L.; Wood, Michael S.; Leeuwenburgh, Christiaan; Dunn, William A.

    2013-01-01

    We have previously shown that autophagy is required for chronological longevity in the budding yeast Saccharomyces cerevisiae. Here we examine the requirements for autophagy during extension of chronological life span (CLS) by calorie restriction (CR). We find that autophagy is upregulated by two CR interventions that extend CLS: water wash CR and low glucose CR. Autophagy is required for full extension of CLS during water wash CR under all growth conditions tested. In contrast, autophagy was not uniformly required for full extension of CLS during low glucose CR, depending on the atg allele and strain genetic background. Leucine status influenced CLS during CR. Eliminating the leucine requirement in yeast strains or adding supplemental leucine to growth media extended CLS during CR. In addition, we observed that both water wash and low glucose CR promote mitochondrial respiration proficiency during aging of autophagy-deficient yeast. In general, the extension of CLS by water wash or low glucose CR was inversely related to respiration deficiency in autophagy-deficient cells. Also, autophagy is required for full extension of CLS under non-CR conditions in buffered media, suggesting that extension of CLS during CR is not solely due to reduced medium acidity. Thus, our findings show that autophagy is: (1) induced by CR, (2) required for full extension of CLS by CR in most cases (depending on atg allele, strain, and leucine availability) and, (3) promotes mitochondrial respiration proficiency during aging under CR conditions. PMID:23337777

  11. 'Zipbody' leucine zipper-fused Fab in E. coli in vitro and in vivo expression systems.

    PubMed

    Ojima-Kato, Teruyo; Fukui, Kansuke; Yamamoto, Hiroaki; Hashimura, Dai; Miyake, Shiro; Hirakawa, Yuki; Yamasaki, Tomomi; Kojima, Takaaki; Nakano, Hideo

    2016-04-01

    A small antibody fragment, fragment of antigen binding (Fab), is favorable for various immunological assays. However, production efficiency of active Fab in microorganisms depends considerably on the clones. In this study, leucine zipper-peptide pairs that dimerize in parallel (ACID-p1 (LZA)/BASE-p1 (LZB) or c-Jun/c-Fos) were fused to the C-terminus of heavy chain (Hc, VH-CH1) and light chain (Lc, VL-CL), respectively, to accelerate the association of Hc and Lc to form Fab in Escherichia coli in vivo and in vitro expression systems. The leucine zipper-fused Fab named 'Zipbody' was constructed using anti-E. coli O157 monoclonal antibody obtained from mouse hybridoma and produced in both in vitro and in vivo expression systems in an active form, whereas Fab without the leucine zipper fusion was not. Similarly, Zipbody of rabbit monoclonal antibody produced in in vitro expression showed significant activity. The purified, mouse Zipbody produced in the E. coli strain Shuffle T7 Express had specificity toward the antigen; in bio-layer interferometry analysis, the KD value was measured to be 1.5-2.0 × 10(-8) M. These results indicate that leucine zipper fusion to Fab C-termini markedly enhances active Fab formation in E. coli. PMID:26902097

  12. Assessment of the metabolic chiral inversion of D-leucine in rat by gas chromatography-mass spectrometry combined with a stable isotope dilution analysis.

    PubMed

    Hasegawa, H; Matsukawa, T; Shinohara, Y; Hashimoto, T

    2000-08-01

    The stereoselective pharmacokinetics of leucine enantiomers in rats has been investigated to evaluate the inversion of D-leucine to L-enantiomer. After a bolus i.v. administration of D- or L-[2H7]leucine to rats, blood samples were obtained over 6 h after administration and analyzed by a stereoselective gas chromatography-mass spectrometry method. Racemic [2H3]leucine was used as an internal standard. The method involved methyl esterification and subsequent chiral derivatization with (+)-alpha-methoxy-alpha-trifluoromethylphenylacetyl chloride to form the diastereomeric amide. The derivatization made possible the separation of leucine enantiomers with good gas chromatographic behavior. Plasma concentration of both D- and L-[2H7]leucine declined biexponentially, with elimination half-lives of 60 and 14 min, respectively. In contrast to the L-enantiomer, the D-enantiomer had a lower systemic clearance. When D-[2H7]leucine was administered, the L-enantiomer was found to rapidly appear in plasma. About 30% of an administered dose of the D-isomer was stereospecifically inverted to the L-enantiomer. There was no measurable inversion of the L- to D-enantiomer. This methodology has made it possible to evaluate the pharmacokinetics of each enantiomer of amino acids and estimate of chiral inversion after administration of D-amino acids. PMID:10901701

  13. Plasma amino acid and serum unesterified fatty acid deficits and the effect of nutritional support in chemotherapy treatment.

    PubMed

    Ching, N; Grossi, C; Jham, G; Angers, J; Zurawinsky, H; Ching, C Y; Nealon, T F

    1984-06-01

    The deficits in plasma amino acids and serum unesterified fatty acids of cancer patients undergoing chemotherapy and/or radiation therapy were studied to delineate the special requirements of the patients and efficacy of our nutritional therapy. Seven general surgery patients and 13 patients treated by the Head-Neck Service had baseline levels measured as part of their nutritional evaluation prior to surgical treatment of their cancers. Fifteen chemotherapy outpatients maintained on their regular diets had fasting levels analyzed. Twenty-six patients who were admitted for their therapy had their intake of the regular hospital diet supplemented with a low-residue enteral diet formula (Vivonex High Nitrogen Diet); parenteral nutrition was used only if their oral intake was totally inadequate. Baseline and sequential measurements were made of plasma amino acid and serum unesterified fatty acid levels by gas liquid chromatographic techniques. Before operation the patients had normal levels of amino acids except for a significant deficiency of threonine and glycine observed in patients with head-neck tumors. Outpatients with and without hepatic metastases had significantly depressed levels of the essential amino acids valine, leucine, threonine, and methionine and the nonessential amino acids serine, glycine, and proline. The baseline levels of the patients admitted for treatment had similar deficiencies except for more evidence of lysine deficiency. Patients supported with total parenteral nutrition had rapid elevation of the amino acid levels. The patients whose intake was supplemented with the oral diets had improvement in their amino acid levels, but the deficiency in the leucine and threonine fractions persisted up to 4 weeks of therapy. Although the lysine levels were normal when first analyzed, significant differences developed in the patients without hepatic metastases after the start of chemotherapy with return to normal only after chemotherapy was discontinued

  14. Stimulating effects of inosine, uridine and glutamine on the tissue distribution of radioactive D-leucine in tumor bearing mice.

    PubMed

    Goto, R; Takeda, A; Tamemasa, O; Chaney, J E; Digenis, G A

    1984-02-01

    This experiment was carried out in search for stimulators of the in vivo uptake of D- and L-leucine by tumor and pancreas for the possible application to gamma-emitter labeled amino acids in nuclear medical diagnosis. Inosine, uridine, and glutamine which are stimulators of the in vitro incorporation of radioactive L-amino acids into some tumor cells significantly enhanced the uptake of D-leucine into the pancreas, while in Ehrlich solid tumor only a little if any increase was observed. Of the compounds tested inosine showed the highest stimulation of pancreas uptake in the range of doses used, resulting in the best pancreas-to-liver concentration ratio, a factor of significant consideration for pancreas imaging. The uptake of L-leucine by the tumor and pancreas was little affected by these compounds. PMID:6739860

  15. Nucleobase and amino acid formation through impacts of meteorites on the early ocean

    NASA Astrophysics Data System (ADS)

    Furukawa, Yoshihiro; Nakazawa, Hiromoto; Sekine, Toshimori; Kobayashi, Takamichi; Kakegawa, Takeshi

    2015-11-01

    The emergence of life's building blocks on the prebiotic Earth was the first crucial step for the origins of life. Extraterrestrial delivery of intact amino acids and nucleobases is the prevailing hypothesis for their availability on prebiotic Earth because of the difficulties associated with the production of these organics from terrestrial carbon and nitrogen sources under plausible prebiotic conditions. However, the variety and amounts of these intact organics delivered by meteorites would have been limited. Previous shock-recovery experiments have demonstrated that meteorite impact reactions could have generated organics on the prebiotic Earth. Here, we report on the simultaneous formation of nucleobases (cytosine and uracil) found in DNA and/or RNA, various proteinogenic amino acids (glycine, alanine, serine, aspartic acid, glutamic acid, valine, leucine, isoleucine, and proline), non-proteinogenic amino acids, and aliphatic amines in experiments simulating reactions induced by extraterrestrial objects impacting on the early oceans. To the best of our knowledge, this is the first report of the formation of nucleobases from inorganic materials by shock conditions. In these experiments, bicarbonate was used as the carbon source. Bicarbonate, which is a common dissolved carbon species in CO2-rich atmospheric conditions, was presumably the most abundant carbon species in the early oceans and in post-impact plumes. Thus, the present results expand the possibility that impact-induced reactions generated various building blocks for life on prebiotic Earth in large quantities through the use of terrestrial carbon reservoirs.

  16. Etching, micro hardness and laser damage threshold studies of a nonlinear optical material L-valine

    NASA Astrophysics Data System (ADS)

    Anbuchezhiyan, M.; Ponnusamy, S.; Muthamizhchelvan, C.; Kanakam, C. C.; Singh, S. P.; Pal, P. K.; Datta, P. K.

    2012-04-01

    A nonlinear optical crystal of L-valine was grown from an aqueous solution containing a small amount of phosphoric acid by the slow evaporation method. The grown crystal was characterized by a single crystal X-ray diffraction to determine the unit cell parameters. The powder X-ray diffraction analysis also confirmed the lattice parameters to be a = 9.6687(7) Å, b = 5.2709(4) Å, c = 12.0371(10) Å and β = 90.805(4)°. The results of the Inductively Coupled Plasma Optical Emission Spectrometry (ICPOES) indicate the presence of a small amount of phosphorus in the grown crystal. The Vickers micro hardness test was performed to study the mechanical strength of the crystals. Chemical etching studies were carried out to analyze the dislocation structure. The laser damaged threshold of the grown crystal was measured to be 11.11 GW/cm2 for 10 ns pulse at 1064 nm, which is higher than that of the standard nonlinear optical crystals like KDP. Second harmonic generation of the grown crystals was also 1.44 times that of KDP.

  17. Nonlinear effects in desorption of valine with fast incident molecular ions

    SciTech Connect

    Salehpour, M.; Fishel, D.L.; Hunt, J.E.

    1988-12-15

    Fast molecular ions as primary particles have been used to study secondary-ion desorption from organic layers. The secondary molecular-ion yield of the amino acid valine (molecular weight, 117) has been measured as a function of the velocity of primary atomic and molecular incident ions. The primary ions used were C/sup +/, O/sup +/, Ar/sup +/, C/sub 2//sup +/, O/sub 2//sup +/ , CO/sup +/, CO/sub 2//sup +/, CH/sup +/, CH/sub 3//sup +/, CF/sup +/, CF/sub 3//sup +/, C/sub 3/F/sub 5//sup +/, and C/sub 4/F/sub 7//sup +/ in the energy range 600 keV--3.7 MeV. The secondary molecular-ion yields, when compared to yields for atomic constituents, unambiguously show that collective effects exist in desorption with incident molecular ions. Results are discussed in the framework of enhancement in the electronic stopping power per atom for molecular ions due to the vicinage of the fast-moving charges in the material. The resulting high-yield enhancements, especially with the use of large incident ions such as C/sub 3/F/sub 5//sup +/ and C/sub 4/F/sub 7//sup +/, are very encouraging for the future of mass spectrometry of large organic molecules.

  18. Structural dynamics of myoglobin: ligand migration and binding in valine 68 mutants.

    PubMed

    Nienhaus, Karin; Deng, Pengchi; Olson, John S; Warren, Joshua J; Nienhaus, G Ulrich

    2003-10-24

    We have combined Fourier transform infrared/temperature derivative (FTIR-TDS) spectroscopy at cryogenic temperatures and flash photolysis at ambient temperature to examine the effects of polar and bulky amino acid replacements of the highly conserved distal valine 68 in sperm whale myoglobin. In FTIR-TDS experiments, the CO ligand can serve as an internal voltmeter that monitors the local electrostatic field not only at the active site but also at intermediate ligand docking sites. Mutations of residue 68 alter size, shape, and electric field of the distal pocket, especially in the vicinity of the primary docking site (state B). As a consequence, the infrared bands associated with the ligand at site B are shifted. The effect is most pronounced in mutants with large aromatic side chains. Polar side chains (threonine or serine) have only little effect on the peak frequencies. Ligands that migrate toward more remote sites C and D give rise to IR bands with altered frequencies. TDS experiments separate the photoproducts according to their recombination temperatures. The rates and extent of ligand migration among internal cavities at cryogenic temperatures can be used to interpret geminate and bimolecular O2 and CO recombination at room temperature. The kinetics of geminate recombination can be explained by steric arguments alone, whereas both the polarity and size of the position 68 side chain play major roles in regulating bimolecular ligand binding from the solvent. PMID:12907676

  19. Structure-activity relations of leucine derivatives reveal critical moieties for cellular uptake and activation of mTORC1-mediated signaling.

    PubMed

    Nagamori, Shushi; Wiriyasermkul, Pattama; Okuda, Suguru; Kojima, Naoto; Hari, Yoshiyuki; Kiyonaka, Shigeki; Mori, Yasuo; Tominaga, Hideyuki; Ohgaki, Ryuichi; Kanai, Yoshikatsu

    2016-04-01

    Among amino acids, leucine is a potential signaling molecule to regulate cell growth and metabolism by activating mechanistic target of rapamycin complex 1 (mTORC1). To reveal the critical structures of leucine molecule to activate mTORC1, we examined the structure-activity relationships of leucine derivatives in HeLa S3 cells for cellular uptake and for the induction of phosphorylation of p70 ribosomal S6 kinase 1 (p70S6K), a downstream effector of mTORC1. The activation of mTORC1 by leucine and its derivatives was the consequence of two successive events: the cellular uptake by L-type amino acid transporter 1 (LAT1) responsible for leucine uptake in HeLa S3 cells and the activation of mTORC1 following the transport. The structural requirement for the recognition by LAT1 was to have carbonyl oxygen, alkoxy oxygen of carboxyl group, amino group and hydrophobic side chain. In contrast, the requirement for mTORC1 activation was more rigorous. It additionally required fixed distance between carbonyl oxygen and alkoxy oxygen of carboxyl group, and amino group positioned at α-carbon. L-Configuration in chirality and appropriate length of side chain with a terminal isopropyl group were also important. This confirmed that LAT1 itself is not a leucine sensor. Some specialized leucine sensing mechanism with rigorous requirement for agonistic structures should exist inside the cells because leucine derivatives not transported by LAT1 did not activate mTORC1. Because LAT1-mTOR axis is involved in the regulation of cell growth and cancer progression, the results from this study may provide a new insight into therapeutics targeting both LAT1 and leucine sensor. PMID:26724922

  20. Identification and quantitation of N-(carboxymethyl)valine adduct in hemoglobin by gas chromatography/mass spectrometry.

    PubMed

    Cai, J; Hurst, H E

    1999-05-01

    A sensitive, specific and reproducible method was developed for the quantitation of the hemoglobin (Hb) adduct N-(carboxymethyl)valine (CMV). This adduct is one of various products from the Maillard reaction, involving reducing sugars and amino acids, proteins or other molecules with a free amino group. Such adducts, including N epsilon-(carboxymethyl)lysine (CML), are called advanced glycation end products (AGE) and have been correlated with aging and severity of diabetes in human tissues. This method was developed to examine the CMV-Hb adduct as a possible AGE formed by reaction of Hb with glucose or other oxidation products. CMV was cleaved selectively from isolated globin using pentafluorophenyl isothiocyanate (PFPITC) in a modified Edman degradation at pH 9.5. The carboxyl group of the adduct was derivatized to its methyl ester with diazomethane. The resulting derivative, 5-isopropyl-1-(methyl acetate)-3-pentafluorophenyl-2-thiohydantoin, was detected by gas chromatography/mass spectrometry with selected ion monitoring (GC/SIM/MS). Quantitation was based on the response factor of the derivative molecular ion (m/z 396) from synthesized CMV and N-(2-carboxyethyl)valine (molecular ion m/z 410) as internal standard. This method exhibits reproducibility and linearity in the range 0.2-100 ng CMV. The limit of quantitation (0.2 ng CMV) gave a signal-to-noise ratio greater than 5:1 using a 1:30 sample aliquot. The GC/SIM/MS method can detect CMV adduct in 5 mg globin samples with relative standard deviations less than 5%. This approach avoids tedious acid hydrolysis and interference from other amino acids. The molecular ion and other CMV derivative ion assignments from samples were confirmed by accurate mass determinations using GC/high resolution SIM/MS. Measurements from random mouse, rat and human globin samples gave mean CMV levels of about 6, 5 and 14 nmol g-1 Hb in these species, respectively. PMID:10390858

  1. Conductometric and fluorometric studies of sodium dodecyl sulphate in aqueous solution and in the presence of amino acids

    NASA Astrophysics Data System (ADS)

    Ali, Anwar; Malik, Nisar Ahmad; Uzair, Sahar; Ali, Maroof

    2014-10-01

    The critical micelle concentration (CMC) of sodium dodecyl sulphate (SDS) in pure water and in the presence of amino acids (0.01, 0.02 and 0.03 mol kg-1), L-valine (Val) and L-leucine (Leu) was determined from conductometric and fluorometric methods using pyrene as luminescence probe. Depression in the CMC at low concentration of amino acids is attributed to the increased hydrophobic-hydrophobic interaction between the non-polar groups of the surfactant, while, at high concentration, amino acids bind strongly with the anion, DS-, head groups of SDS, thereby, delaying the micelle formation, resulting in increased CMC. A pronounced decrease in the CMC, while a marked increase in λ0+, with decrease in the solvated radius (rather than crystal radius) of the counterions is observed. Negative values of ΔG0m and ΔH0m indicate that micellisation of SDS in the presence of amino acids is thermodynamically spontaneous and exothermic. Highest negative value of ΔH0m in 0.01 m Val, with lowest CMC value, shows that 0.01 m aqueous Val is the most suitable medium favouring the micellisation of SDS. Decrease in I1/I3 from Val to Leu confirms the relative hydrophobicity of two amino acids. The observed values of the packing parameter, P, of SDS in water and in aqueous amino acids suggest that micelles formed are spherical in nature.

  2. Pushing product formation to its limit: metabolic engineering of Corynebacterium glutamicum for L-leucine overproduction.

    PubMed

    Vogt, Michael; Haas, Sabine; Klaffl, Simon; Polen, Tino; Eggeling, Lothar; van Ooyen, Jan; Bott, Michael

    2014-03-01

    Using metabolic engineering, an efficient L-leucine production strain of Corynebacterium glutamicum was developed. In the wild type of C. glutamicum, the leuA-encoded 2-isopropylmalate synthase (IPMS) is inhibited by low L-leucine concentrations with a K(i) of 0.4 mM. We identified a feedback-resistant IMPS variant, which carries two amino acid exchanges (R529H, G532D). The corresponding leuA(fbr) gene devoid of the attenuator region and under control of a strong promoter was integrated in one, two or three copies into the genome and combined with additional genomic modifications aimed at increasing L-leucine production. These modifications involved (i) deletion of the gene encoding the repressor LtbR to increase expression of leuBCD, (ii) deletion of the gene encoding the transcriptional regulator IolR to increase glucose uptake, (iii) reduction of citrate synthase activity to increase precursor supply, and (iv) introduction of a gene encoding a feedback-resistant acetohydroxyacid synthase. The production performance of the resulting strains was characterized in bioreactor cultivations. Under fed-batch conditions, the best producer strain accumulated L-leucine to levels exceeding the solubility limit of about 24 g/l. The molar product yield was 0.30 mol L-leucine per mol glucose and the volumetric productivity was 4.3 mmol l⁻¹ h⁻¹. These values were obtained in a defined minimal medium with a prototrophic and plasmid-free strain, making this process highly interesting for industrial application. PMID:24333966

  3. Regions of the Bacillus subtilis ilv-leu operon involved in regulation by leucine.

    PubMed Central

    Grandoni, J A; Fulmer, S B; Brizzio, V; Zahler, S A; Calvo, J M

    1993-01-01

    The ilv-leu operon of Bacillus subtilis is regulated in part by transcription attenuation. The cis-acting elements required for regulation by leucine lie within a 683-bp fragment of DNA from the region upstream of ilvB, the first gene of the operon. This fragment contains the ilv-leu promoter and 482 bp of the ilv-leu leader region. Spontaneous mutations that lead to increased expression of the operon were shown to lie in an imperfect inverted repeat encoding the terminator stem within the leader region. Mutations within the inverted repeat of the terminator destroyed most of the leucine-mediated repression. The remaining leucine-mediated repression probably resulted from a decrease in transcription initiation. A systematic analysis of other deletions within the ilv-leu leader region identified a 40-bp region required for the derepression that occurred during leucine limitation. This region lies within a potential RNA stem-and-loop structure that is probably required for leucine-dependent control. Deletion analysis also suggested that alternate secondary structures proximal to the terminator are involved in allowing transcription to proceed beyond the terminator. Additional experiments suggested that attenuation of the ilv-leu operon is not dependent on coupling translation to transcription of the leader region. Our data support a model proposed by Grundy and Henkin (F. J. Grundy and T. M. Henkin, Cell 74:475-482, 1993) in which uncharged tRNA acts as a positive regulatory factor to increase gene expression during amino acid limitation. Images PMID:8244927

  4. Targeting of glycoprotein I (gE) of varicella-zoster virus to the trans-Golgi network by an AYRV sequence and an acidic amino acid-rich patch in the cytosolic domain of the molecule.

    PubMed Central

    Zhu, Z; Hao, Y; Gershon, M D; Ambron, R T; Gershon, A A

    1996-01-01

    Previous studies suggested that varicella-zoster virus (VZV) envelope glycoproteins (gps) are selectively transported to the trans-Golgi network (TGN) and that the cytosolic domain of gpI (gE) targets it to the TGN. To identify targeting signals in the gpI cytosolic domain, intracellular protein trafficking was studied in transfected cells expressing chimeric proteins in which a full-length or mutated gpI cytosolic domain was fused to the gpI transmembrane domain and interleukin-2 receptor (tac) ectodomain. Expressed protein was visualized with antibodies to tac. A targeting sequence (AYRV) and a second, acidic amino acid-rich region of the gpI cytosolic domain (putative signal patch) were each sufficient to cause expressed protein to colocalize with TGN markers. This targeting was lost when the tyrosine of the AYRV sequence was replaced with glycine or lysine, when arginine was replaced with glutamic acid, or when valine was substituted with lysine. In contrast, tyrosine could be replaced by phenylalanine and valine could be substituted with leucine. Mutation of alanine to aspartic acid or deletion of alanine abolished TGN targeting. Exposure of transfected cells to antibodies to the tac ectodomain revealed that the TCN targeting of expressed tac-gpI chimeric proteins occurred as a result of selective retrieval from the plasmalemma. These data suggest that the AYRV sequence and a second signaling patch in the cytosolic domain of gpI are responsible for its targeting to the TGN. The observations also support the hypothesis that the TGN plays a critical role in the envelopment of VZV. PMID:8794291

  5. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Leucine aminopeptidase test system. 862.1460 Section 862.1460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1460 Leucine aminopeptidase...

  6. Prolonged leucine supplementation does not augment muscle mass or affect glycemic control in elderly type 2 diabetic men.

    PubMed

    Leenders, Marika; Verdijk, Lex B; van der Hoeven, Letty; van Kranenburg, Janneau; Hartgens, Fred; Wodzig, Will K W H; Saris, Wim H M; van Loon, Luc J C

    2011-06-01

    The loss of muscle mass with aging has been, at least partly, attributed to a blunted muscle protein synthetic response to food intake. Leucine coingestion has been reported to stimulate postprandial insulin release and augment postprandial muscle protein accretion. We assessed the clinical benefits of 6 mo of leucine supplementation in elderly, type 2 diabetes patients. Sixty elderly males with type 2 diabetes (age, 71 ± 1 y; BMI, 27.3 ± 0.4 kg/m(2)) were administered 2.5 g L-leucine (n = 30) or a placebo (n = 30) with each main meal during 6 mo of nutritional intervention (7.5 g/d leucine or placebo). Body composition, muscle fiber characteristics, muscle strength, glucose homeostasis, and basal plasma amino acid and lipid concentrations were assessed prior to, during, and after intervention. Lean tissue mass did not change or differ between groups and at 0, 3, and 6 mo were 61.9 ± 1.1, 62.2 ± 1.1, and 62.0 ± 1.0 kg, respectively, in the leucine group and 62.2 ± 1.3, 62.2 ± 1.3, and 62.2 ± 1.3 kg in the placebo group. There also were no changes in body fat percentage, muscle strength, and muscle fiber type characteristics. Blood glycosylated hemoglobin did not change or differ between groups and was 7.1 ± 0.1% in the leucine group and 7.2 ± 0.2% in the placebo group. Consistent with this, oral glucose insulin sensitivity and plasma lipid concentrations did not change or differ between groups. We conclude that prolonged leucine supplementation (7.5 g/d) does not modulate body composition, muscle mass, strength, glycemic control, and/or lipidemia in elderly, type 2 diabetes patients who habitually consume adequate dietary protein. PMID:21525248

  7. Leucine for retention of lean mass on a hypocaloric diet.

    PubMed

    Jitomir, Jean; Willoughby, Darryn S

    2008-12-01

    As obesity rates continue to climb, there is a pressing need for novel weight loss techniques. However, the energy-restricted diets recommended for weight loss typically result in significant amounts of lean tissue loss, in addition to the desired body fat loss. Leucine, a supported anticatabolic agent, has shown promise in research at many levels. First, leucine is known to stimulate the mammalian target of rapamycin pathway, which initiates translation and protein synthesis in muscle cells. Furthermore, leucine may help to regulate blood glucose levels by promoting gluconeogenesis. Finally, several recent studies provide evidence that leucine aids in the retention of lean mass in a hypocaloric state. The aim of this paper is to review relevant leucine research in the three areas described and assess its potential as supplement for obese individuals. PMID:19053849

  8. Acute effects of enteral leucine supplementation of a low protein diet on muscle protein synthesis in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protein synthesis and eukaryotic initiation factor (eIF) activation are increased in skeletal muscle of neonatal pigs parenterally infused with insulin and amino acids (AA), particularly leucine. We hypothesized that enteral Leu supplementation of a low protein diets in neonatal pigs will acutely in...

  9. Rapamycin blocks leucine-induced protein synthesis by suppressing mTORC1 activation in skeletal muscle of neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Skeletal muscle in the neonate grows at a rapid rate due in part to an enhanced sensitivity to the postprandial rise in amino acids, particularly leucine (Leu). To elucidate the molecular mechanism by which Leu stimulates protein synthesis in neonatal muscle, overnight fasted 7-day-old piglets were...

  10. Chemical Composition, Nitrogen Fractions and Amino Acids Profile of Milk from Different Animal Species.

    PubMed

    Rafiq, Saima; Huma, Nuzhat; Pasha, Imran; Sameen, Aysha; Mukhtar, Omer; Khan, Muhammad Issa

    2016-07-01

    Milk composition is an imperative aspect which influences the quality of dairy products. The objective of study was to compare the chemical composition, nitrogen fractions and amino acids profile of milk from buffalo, cow, sheep, goat, and camel. Sheep milk was found to be highest in fat (6.82%±0.04%), solid-not-fat (11.24%±0.02%), total solids (18.05%±0.05%), protein (5.15%±0.06%) and casein (3.87%±0.04%) contents followed by buffalo milk. Maximum whey proteins were observed in camel milk (0.80%±0.03%), buffalo (0.68%±0.02%) and sheep (0.66%±0.02%) milk. The non-protein-nitrogen contents varied from 0.33% to 0.62% among different milk species. The highest r-values were recorded for correlations between crude protein and casein in buffalo (r = 0.82), cow (r = 0.88), sheep (r = 0.86) and goat milk (r = 0.98). The caseins and whey proteins were also positively correlated with true proteins in all milk species. A favorable balance of branched-chain amino acids; leucine, isoleucine, and valine were found both in casein and whey proteins. Leucine content was highest in cow (108±2.3 mg/g), camel (96±2.2 mg/g) and buffalo (90±2.4 mg/g) milk caseins. Maximum concentrations of isoleucine, phenylalanine, and histidine were noticed in goat milk caseins. Glutamic acid and proline were dominant among non-essential amino acids. Conclusively, current exploration is important for milk processors to design nutritious and consistent quality end products. PMID:26954163

  11. Chemical Composition, Nitrogen Fractions and Amino Acids Profile of Milk from Different Animal Species

    PubMed Central

    Rafiq, Saima; Huma, Nuzhat; Pasha, Imran; Sameen, Aysha; Mukhtar, Omer; Khan, Muhammad Issa

    2016-01-01

    Milk composition is an imperative aspect which influences the quality of dairy products. The objective of study was to compare the chemical composition, nitrogen fractions and amino acids profile of milk from buffalo, cow, sheep, goat, and camel. Sheep milk was found to be highest in fat (6.82%±0.04%), solid-not-fat (11.24%±0.02%), total solids (18.05%±0.05%), protein (5.15%±0.06%) and casein (3.87%±0.04%) contents followed by buffalo milk. Maximum whey proteins were observed in camel milk (0.80%±0.03%), buffalo (0.68%±0.02%) and sheep (0.66%±0.02%) milk. The non-protein-nitrogen contents varied from 0.33% to 0.62% among different milk species. The highest r-values were recorded for correlations between crude protein and casein in buffalo (r = 0.82), cow (r = 0.88), sheep (r = 0.86) and goat milk (r = 0.98). The caseins and whey proteins were also positively correlated with true proteins in all milk species. A favorable balance of branched-chain amino acids; leucine, isoleucine, and valine were found both in casein and whey proteins. Leucine content was highest in cow (108±2.3 mg/g), camel (96±2.2 mg/g) and buffalo (90±2.4 mg/g) milk caseins. Maximum concentrations of isoleucine, phenylalanine, and histidine were noticed in goat milk caseins. Glutamic acid and proline were dominant among non-essential amino acids. Conclusively, current exploration is important for milk processors to design nutritious and consistent quality end products. PMID:26954163

  12. Novel fatty acid methyl esters from the actinomycete Micromonospora aurantiaca

    PubMed Central

    Bruns, Hilke; Riclea, Ramona

    2011-01-01

    Summary The volatiles released by Micromonospora aurantiaca were collected by means of a closed-loop stripping apparatus (CLSA) and analysed by GC–MS. The headspace extracts contained more than 90 compounds from different classes. Fatty acid methyl esters (FAMEs) comprised the major compound class including saturated unbranched, monomethyl and dimethyl branched FAMEs in diverse structural variants: Unbranched, α-branched, γ-branched, (ω−1)-branched, (ω−2)-branched, α- and (ω−1)-branched, γ- and (ω−1)-branched, γ- and (ω−2)-branched, and γ- and (ω−3)-branched FAMEs. FAMEs of the last three types have not been described from natural sources before. The structures for all FAMEs have been suggested based on their mass spectra and on a retention index increment system and verified by the synthesis of key reference compounds. In addition, the structures of two FAMEs, methyl 4,8-dimethyldodecanoate and the ethyl-branched compound methyl 8-ethyl-4-methyldodecanoate were deduced from their mass spectra. Feeding experiments with isotopically labelled [2H10]leucine, [2H10]isoleucine, [2H8]valine, [2H5]sodium propionate, and [methyl-2H3]methionine demonstrated that the responsible fatty acid synthase (FAS) can use different branched and unbranched starter units and is able to incorporate methylmalonyl-CoA elongation units for internal methyl branches in various chain positions, while the methyl ester function is derived from S-adenosyl methionine (SAM). PMID:22238549

  13. Shock synthesis of amino acids in simulated primitive environments.

    NASA Technical Reports Server (NTRS)

    Bar-Nun, A.; Bar-Nun, N.; Bauer, S. H.; Sagan, C.

    1971-01-01

    A single pulse shock tube of a uniform bore was used in the experiments. The reaction mixture consisted of 3.3 per cent methane, 11 per cent ethane, and 5.6 per cent ammonia, diluted with ultra-pure argon. The formation of glycine, alanine, valine, and leucine under conditions of shock heating was observed. Thermodynamic relations are discussed together with questions of conversion efficiency.

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

    PubMed

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

    2014-01-01

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

  15. Genetically variable taste sensitivity to D-amino acids in mice.

    PubMed

    Ninomiya, Y; Nomura, T; Katsukawa, H

    1992-11-20

    Behavioral and neural responses to D-amino acids were compared between two inbred strains, C57BL and BALB mice. In both strains, an aversion conditioned to D-valine, D-leucine, D-methionine, D-histidine or D-tryptophan generalized to sucrose, whereas an aversion to D-alanine or D-serine did not generalize to sucrose. Generalization patterns across various test stimuli for each of these 7 D-amino acids were significantly correlated between two strains. However, an aversion conditioned to D-phenylalanine generalized to sucrose in C57BL mice, but not in BALB mice. Application of a proteolytic enzyme, Pronase E, to the tongue reduced chorda tympani responses to sucrose and D-amino acids to which a conditioned aversion generalized to sucrose. Again, only in C57BL mice, Pronase inhibited D-phenylalanine responses. These comparable results indicate that sweet taste response is genetically highly variable only to D-phenylalanine among 8 D-amino acids tested. PMID:1467999

  16. Echinococcus granulosus: absorption of cycloleucine and alpha-aminoisobutyric acid by protoscoleces.

    PubMed

    Jeffs, S A; Arme, C

    1986-02-01

    Protoscoleces of Echinococcus granulosus absorb the amino acids cycloleucine and alpha-aminoisobutyric acid (AIB) by a combination of mediated uptake and diffusion. After correcting for the latter, values for Kt and Vmax of 0.124 mM and 0.947 nmoles/mg protein/2 min for cycloleucine were calculated; corresponding values for AIB were 0.039 mM and 0.139 nmoles/mg protein/2 min. Both amino acids were accumulated against a concentration gradient and a comparison of Kt and Ki values determined in mutual inhibition experiments suggested that both cycloleucine and AIB share a common uptake locus (loci). Cycloleucine uptake was pH-dependent and could be inhibited by a variety of other amino acids. Neither D- nor L-proline inhibited cycloleucine absorption but D-methionine, D-alanine, D-leucine, D-valine and D-serine were much more effective inhibitors than their L-counterparts. PMID:3083393

  17. The effect of fermentation and storage on free amino acids of tarhana.

    PubMed

    Erbas, M; Ertugay, M F; Erbas, M O; Certel, M

    2005-08-01

    A study on the evaluation of free amino acids (FAAs) in tarhana during fermentation and storage was performed. The FAAs in tarhana were determined by RP-HPLC with a fluorescence detector following extraction from the sample and derivatization with dansyl chloride. The amount of FAAs increased significantly (p<0.01) during fermentation and storage. The increase in the content of total free amino acids (TFAAs) and total free essential amino acids (TFEAAs) of fermented tarhana, which was used with yogurt bacteria and baker's yeast, was 57% and 93%, respectively. The amino acids primarily responsible for the increase were valine and tryptophan followed by methionine, alanine, isoleucine + leucine, phenylalanine, arginine, proline, and lysine. The TFAA content of tarhana at the end of fermentation was found to be 8% of total protein (16.8%). The ratio of TFEAAs/TFAAs was initially 0.46 and increased to 0.57 at the end of fermentation. The TFAA content of wet tarhanas was higher than that of the dry counterpart. It was found that the TFAA content of dry tarhana was 25% lower than the fresh wet tarhana (FWT), at the end of fermentation. It was concluded that the decrease in FAAs in dry tarhana was due to the Maillard reaction and partial degradation of FAAs during dehydration. PMID:16236596

  18. Deduced amino acid sequence of human pulmonary surfactant proteolipid: SPL(pVal)

    SciTech Connect

    Whitsett, J.A.; Glasser, S.W.; Korfhagen, T.R.; Weaver, T.E.; Clark, J.; Pilot-Matias, T.; Meuth, J.; Fox, J.L.

    1987-05-01

    Hydrophobic, proteolipid-like protein of Mr 6500 was isolated from ether/ethanol extracts of human, canine and bovine pulmonary surfactant. Amino acid composition of the protein demonstrated a remarkable abundance of hydrophobic residues, particularly valine and leucine. The N-terminal amino acid sequence of the human protein was determined: N-Leu-Ile-Pro-Cys-Cys-Pro-Val-Asn-Leu-Lys-Arg-Leu-Leu-Ile-Val4... An oligonucleotide probe was used to screen an adult human lung cDNA library and resulted in detection of cDNA clones with predicted amino acid sequence with close identity to the N-terminal amino acid sequence of the human peptide. SPL(pVal) was found within the reading frame of a larger peptide. SPL(pVal) results from proteolytic processing of a larger preprotein. Northern blot analysis detected in a single 1.0 kilobase SPL(pVal) RNA which was less abundant in fetal than in adult lung. Mixtures of purified canine and bovine SPL(pVal) and synthetic phospholipids display properties of rapid adsorption and surface tension lowering activity characteristic of surfactant. Human SPL(pVal) is a pulmonary surfactant proteolipid which may therefore be useful in combination with phospholipids and/or other surfactant proteins for the treatment of surfactant deficiency such as hyaline membrane disease in newborn infants.

  19. An electrochemical sensor based on cellulose nanocrystal for the enantioselective discrimination of chiral amino acids.

    PubMed

    Bi, Qing; Dong, Shuqing; Sun, Yaming; Lu, Xiaoquan; Zhao, Liang

    2016-09-01

    A novel electrochemical sensor based on 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanocrystals (TOCNCs) and l-cystines (l-Cys) modified Au electrode (TOCNC/l-Cys/Au) has been fabricated for detection and discrimination of the enantiomers of phenylalanine (Phe), leucine (Leu), and valine (Val). The three amino acids are in connection with metabolism diseases. The TOCNC/l-Cys/Au electrode exhibited obvious peak current difference for the amino acid enantiomers by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The TOCNCs on the electrode surface expressed different interactions with d- and l-amino acids, so the electrochemical recognitions of the three amino acid enantiomers were achieved. TOCNCs were characterized by Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM). The modified electrodes were characterized by SEM and electrochemical techniques. According to DPV, peak currents of the two enantiomers decreased linearly with their concentrations. Furthermore, satisfactory results were obtained when this electrode was applied to measure the d- and l-Phe mixture. The experimental results show that TOCNCs are suitable material for chiral sensor. The contrast of serum sample of healthy people and patients with type 2 diabetes also was proposed, and significant difference was exhibited on the modified electrode. This work is significant for the screening, diagnosis, and treatment of multiple metabolic diseases. PMID:27288559

  20. The role of the N-terminal leucine residue in snake venom cardiotoxin II (Naja naja atra).

    PubMed

    Wu, C Y; Chen, W C; Ho, C L; Chen, S T; Wang, K T

    1997-04-28

    The N-terminal leucine residue of snake venom cardiotoxin II (CTX II) (Naja naja atra) was systematically replaced with D-leucine (CTXII-L1-D-L), glycine (CTXII-L1G) or deleted [CTXII-(2-60)] to study the role of leucine residue in CTX II molecule. CTX II, CTXL1-D-L, CTXL1G and CTX(2-60) were produced by chemical synthesis method and purified by high performance liquid chromatography. Owing to folding problem in CTXII-(2-60), only CTX II, CTXII-L1-D-L and CTXII-L1G were produced in a pure form and characterized by amino acid analysis, mass spectrometry and peptide mapping. In the structural aspect, changing the Leu-1 by D-Leu or Gly causes a drastic alteration in the whole CTX II structure as detected by circular dichroism, 1-anilino-naphthalene-8-sulfonate (ANS) fluorescence assay. In the functional aspect, both CTXII-L1-D-L and CTXII-L1G are still retained substantial biological activity of CTX II. Therefore, the results indicate that both the chirality and the side-chain of the N-terminal leucine residue of CTX II are important elements in maintaining the whole CTX II structure. In addition, this study is the first report in elucidating the reason why the first N-terminal residue of most CTXs (90.3%) is leucine residue. PMID:9168920

  1. Leucine and Protein Metabolism in Obese Zucker Rats

    PubMed Central

    She, Pengxiang; Olson, Kristine C.; Kadota, Yoshihiro; Inukai, Ayami; Shimomura, Yoshiharu; Hoppel, Charles L.; Adams, Sean H.; Kawamata, Yasuko; Matsumoto, Hideki; Sakai, Ryosei; Lang, Charles H.; Lynch, Christopher J.

    2013-01-01

    Branched-chain amino acids (BCAAs) are circulating nutrient signals for protein accretion, however, they increase in obesity and elevations appear to be prognostic of diabetes. To understand the mechanisms whereby obesity affects BCAAs and protein metabolism, we employed metabolomics and measured rates of [1-14C]-leucine metabolism, tissue-specific protein synthesis and branched-chain keto-acid (BCKA) dehydrogenase complex (BCKDC) activities. Male obese Zucker rats (11-weeks old) had increased body weight (BW, 53%), liver (107%) and fat (∼300%), but lower plantaris and gastrocnemius masses (−21–24%). Plasma BCAAs and BCKAs were elevated 45–69% and ∼100%, respectively, in obese rats. Processes facilitating these rises appeared to include increased dietary intake (23%), leucine (Leu) turnover and proteolysis [35% per g fat free mass (FFM), urinary markers of proteolysis: 3-methylhistidine (183%) and 4-hydroxyproline (766%)] and decreased BCKDC per g kidney, heart, gastrocnemius and liver (−47–66%). A process disposing of circulating BCAAs, protein synthesis, was increased 23–29% by obesity in whole-body (FFM corrected), gastrocnemius and liver. Despite the observed decreases in BCKDC activities per gm tissue, rates of whole-body Leu oxidation in obese rats were 22% and 59% higher normalized to BW and FFM, respectively. Consistently, urinary concentrations of eight BCAA catabolism-derived acylcarnitines were also elevated. The unexpected increase in BCAA oxidation may be due to a substrate effect in liver. Supporting this idea, BCKAs were elevated more in liver (193–418%) than plasma or muscle, and per g losses of hepatic BCKDC activities were completely offset by increased liver mass, in contrast to other tissues. In summary, our results indicate that plasma BCKAs may represent a more sensitive metabolic signature for obesity than BCAAs. Processes supporting elevated BCAA]BCKAs in the obese Zucker rat include increased dietary intake, Leu and

  2. Changes in plasma osmolality, cortisol and amino acid levels of tongue sole ( Cynoglossus semilaevis) at different salinities

    NASA Astrophysics Data System (ADS)

    Wang, Guodong; Xu, Kefeng; Tian, Xiangli; Dong, Shuanglin; Fang, Ziheng

    2015-10-01

    A serial of salinity transferring treatments were performed to investigate the osmoregulation of tongue sole ( Cynoglossus semilaevis). Juvenile tongue sole were directly transferred from a salinity of 30 to 0, 10, 20, 30, 40 and 50. Blood sampling was performed for each treatment after 0, 1, 6 and 12 h, as well as after 1, 2, 4, 8, 16 and 32 d. The plasma osmolality, cortisol and free amino acids were assessed. Under the experimental conditions, no fish died after acute salinity transfer. The plasma cortisol level increased 1 h after the abrupt transfer from a salinity of 30 to that of 0, 40 and 50, and decreased from 6 h to 8 d after transfer. Similar trends were observed in the changes of plasma osmolality. The plasma free amino acids concentration showed a `U-shaped' relationship with salinity after being transferred to different salinities for 4 days. More obvious changes of plasma free amino acid concentration occurred under hyper-osmotic conditions than under hypo-osmotic conditions. The concentrations of valine, isoleucine, lysine, glutamic acid, glycine, proline and taurine increased with rising salinity. The plasma levels of threonine, leucine, arginine, serine, and alanine showed a `U-shaped' relationship with salinity. The results of this study suggested that free amino acids might have important effects on osmotic acclimation in tongue sole.

  3. Ion formation upon electron collisions with valine embedded in helium nanodroplets

    NASA Astrophysics Data System (ADS)

    Weinberger, Nikolaus; Ralser, Stefan; Renzler, Michael; Harnisch, Martina; Kaiser, Alexander; Denifl, Stefan; Böhme, Diethard K.; Scheier, Paul

    2016-04-01

    We report here experimental results for the electron ionization of large superfluid helium nanodroplets with sizes of about 105 atoms that are doped with valine and clusters of valine. Spectra of both cations and anions were monitored with high-resolution time-of-flight mass spectrometry (mass resolution >4000). Clear series of peaks with valine cluster sizes up to at least 40 and spaced by the mass of a valine molecule are visible in both the cation and anion spectra. Ion efficiency curves are presented for selected cations and anions at electron energies up to about 40 eV and these provide insight into the mode of ion formation. The measured onset of 24.59 eV for cations is indicative of valine ionization by He+ whereas broad resonances at 2, 10 and 22 eV (and beyond) in the formation of anions speak to the occurrence of various modes of dissociative electron attachment by collisions with electrons or He*- and the influence of droplet size on the relative importance of these processes. Comparisons are also made with gas phase results and these provide insight into a matrix effect within the superfluid helium nanodroplet. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  4. Leucine supplementation of a chronically restricted protein and energy diet enhances mTOR pathway activation but not muscle protein synthesis in neonatal pigs.

    PubMed

    Manjarín, Rodrigo; Columbus, Daniel A; Suryawan, Agus; Nguyen, Hanh V; Hernandez-García, Adriana D; Hoang, Nguyet-Minh; Fiorotto, Marta L; Davis, Teresa

    2016-01-01

    Suboptimal nutrient intake represents a limiting factor for growth and long-term survival of low-birth weight infants. The objective of this study was to determine if in neonates who can consume only 70 % of their protein and energy requirements for 8 days, enteral leucine supplementation will upregulate the mammalian target of rapamycin (mTOR) pathway in skeletal muscle, leading to an increase in protein synthesis and muscle anabolism. Nineteen 4-day-old piglets were fed by gastric tube 1 of 3 diets, containing (kg body weight(-1) · day(-1)) 16 g protein and 190 kcal (CON), 10.9 g protein and 132 kcal (R), or 10.8 g protein + 0.2 % leucine and 136 kcal (RL) at 4-h intervals for 8 days. On day 8, plasma AA and insulin levels were measured during 6 post-feeding intervals, and muscle protein synthesis rate and mTOR signaling proteins were determined at 120 min post-feeding. At 120 min, leucine was highest in RL (P < 0.001), whereas insulin, isoleucine and valine were lower in RL and R compared to CON (P < 0.001). Compared to RL and R, the CON diet increased (P < 0.01) body weight, protein synthesis, phosphorylation of S6 kinase (p-S6K1) and 4E-binding protein (p-4EBP1), and activation of eukaryotic initiation factor 4 complex (eIF4E · eIF4G). RL increased (P ≤ 0.01) p-S6K1, p-4EBP1 and eIF4E · eIF4G compared to R. In conclusion, when protein and energy intakes are restricted for 8 days, leucine supplementation increases muscle mTOR activation, but does not improve body weight gain or enhance skeletal muscle protein synthesis in neonatal pigs. PMID:26334346

  5. Capsaicin Synthesis Requires in Situ Phenylalanine and Valine Formation in in Vitro Maintained Placentas from Capsicum chinense.

    PubMed

    Baas-Espinola, Fray M; Castro-Concha, Lizbeth A; Vázquez-Flota, Felipe A; Miranda-Ham, María L

    2016-01-01

    Capsaicinoids (CAP) are nitrogenous metabolites formed from valine (Val) and phenylalanine (Phe) in the placentas of hot Capsicum genotypes. Placentas of Habanero peppers can incorporate inorganic nitrogen into amino acids and have the ability to secure the availability of the required amino acids for CAP biosynthesis. In order to determine the participation of the placental tissue as a supplier of these amino acids, the effects of blocking the synthesis of Val and Phe by using specific enzyme inhibitors were analyzed. Isolated placentas maintained in vitro were used to rule out external sources' participation. Blocking Phe synthesis, through the inhibition of arogenate dehydratase, significantly decreased CAP accumulation suggesting that at least part of Phe required in this process has to be produced in situ. Chlorsulfuron inhibition of acetolactate synthase, involved in Val synthesis, decreased not only Val accumulation but also that of CAP, pointing out that the requirement for this amino acid can also be fulfilled by this tissue. The presented data demonstrates that CAP accumulation in in vitro maintained placentas can be accomplished through the in situ availability of Val and Phe and suggests that the synthesis of the fatty acid chain moiety may be a limiting factor in the biosynthesis of these alkaloids. PMID:27338325

  6. Influence of cold stress on contents of soluble sugars, vitamin C and free amino acids including gamma-aminobutyric acid (GABA) in spinach (Spinacia oleracea).

    PubMed

    Yoon, Young-Eun; Kuppusamy, Saranya; Cho, Kye Man; Kim, Pil Joo; Kwack, Yong-Bum; Lee, Yong Bok

    2017-01-15

    The contents of soluble sugars (sucrose, fructose, glucose, maltose and raffinose), vitamin C and free amino acids (34 compounds, essential and non-essential) were quantified in open-field and greenhouse-grown spinaches in response to cold stress using liquid chromatography. In general, greenhouse cultivation produced nutritionally high value spinach in a shorter growing period, where the soluble sugars, vitamin C and total amino acids concentrations, including essential were in larger amounts compared to those grown in open-field scenarios. Further, low temperature exposure of spinach during a shorter growth period resulted in the production of spinach with high sucrose, ascorbate, proline, gamma-aminobutyric acid, valine and leucine content, and these constitute the most important energy/nutrient sources. In conclusion, cultivation of spinach in greenhouse at a low temperature (4-7°C) and exposure for a shorter period (7-21days) before harvest is recommended. This strategy will produce a high quality product that people can eat. PMID:27542466

  7. Maple syrup urine disease

    MedlinePlus

    ... People with this condition cannot break down the amino acids leucine, isoleucine, and valine. This leads to a ... be done to check for this disorder: Plasma amino acid test Urine organic acid test Genetic testing There ...

  8. Simultaneous analysis of the non-canonical amino acids norleucine and norvaline in biopharmaceutical-related fermentation processes by a new ultra-high performance liquid chromatography approach.

    PubMed

    Biermann, Michael; Bardl, Bettina; Vollstädt, Sebastian; Linnemann, Julia; Knüpfer, Uwe; Seidel, Guido; Horn, Uwe

    2013-04-01

    In this study, a precise and reliable ultra-high performance liquid chromatography (UHPLC) method for the simultaneous determination of non-canonical (norvaline and norleucine) and standard amino acids (aspartic acid, glutamic acid, serine, histidine, glycine, threonine, arginine, tyrosine, methionine, valine, phenylalanine, isoleucine, leucine) in biopharmaceutical-related fermentation processes was established. After pre-column derivatization with ortho-phthaldialdehyde and 2-mercaptoethanol, the derivatives were separated on a sub-2 μm particle C18 reverse-phase column. Identification and quantification of amino acids were carried out by fluorescence detection. To test method feasibility on standard HPLC instruments, the assay was properly transferred to a core-shell particle C18 reverse-phase column. The limits of detection showed excellent sensitivity by values from 0.06 to 0.17 pmol per injection and limits of quantification between 0.19 and 0.89 pmol. In the present study, the newly established UHPLC method was applied to a recombinant antibody Escherichia coli fermentation process for the analysis of total free amino acids. We were able to specifically detect and quantify the unfavorable amino acids in such complex samples. Since we observed trace amounts of norvaline and norleucine during all fermentation phases, an obligatory process monitoring should be considered to improve quality of recombinant protein drugs in future. PMID:23306451

  9. Nucleotide sequences and characterization of liv genes encoding components of the high-affinity branched-chain amino acid transport system in Salmonella typhimurium.

    PubMed

    Matsubara, K; Ohnishi, K; Kiritani, K

    1992-07-01

    A 7.6-kb fragment of Salmonella typhimurium LT2 containing the liv gene cluster, which specifies the high-affinity branched-chain amino acid transport system (LIV-I), has been isolated. The upstream region contains the livB and livC genes encoding the leucine-isoleucine-valine-threonine and leucine-specific binding proteins, respectively. In this study, the nucleotide sequence of the 4-kb downstream segment was determined and found to contain four reading frames, designated as livA, livE, livF, and livG, that encode putative membrane-associated proteins. The livA and livE genes encode hydrophobic proteins composed of 308 and 425 amino acid residues, respectively. The livF and livG genes encode hydrophilic proteins of 255 and 237 amino acids, respectively; both the proteins contain consensus amino acid sequences found in proteins with ATP-binding sites. These four genes linked together have a potential rho-independent transcriptional terminator adjacent to the 3'-end of livG. No promoter sequence was found in the immediate upstream region of the livAEFG cluster. The livA, livE, livF, and livG gene products were identified as proteins with apparent M(r)s of 25,500, 34,500, 28,000, and 26,000, respectively, by SDS-polyacryl-amide gel electrophoresis. The deduced amino acid sequences of these four proteins showed strong homology to those of the corresponding membrane-associated proteins required for the high-affinity branched-chain amino acid transport systems from both Escherichia coli and Pseudomonas aeruginosa. PMID:1429514

  10. Design, synthesis, and fungicidal activities of imino diacid analogs of valine amide fungicides.

    PubMed

    Sun, Man; Yang, Hui-Hui; Tian, Lei; Li, Jian-Qiang; Zhao, Wei-Guang

    2015-12-15

    The novel imino diacid analogs of valine amides were synthesized via several steps, including the protection, amidation, deprotection, and amino alkylation of valine, with the resulting structures confirmed by (1)H and (13)C NMR and HRMS. Bioassays showed that some of these compounds exhibited good fungicidal activity. Notably, isopropyl 2-((1-((1-(3-fluorophenyl)ethyl)amino)-3-methyl-1-oxobutan-2-yl)amino)propanoate 5i displayed significant levels of control, at 50%, against Erysiphe graminis at 3.9μM as well as a level of potency very similar to the reference azoxystrobin, which gave 60% activity at this concentration. The present work demonstrates that imino diacid analogs of valine amides could be potentially useful key compounds for the development of novel fungicides against wheat powdery mildew. PMID:26546215

  11. Water adsorption on etched hydrophobic surfaces of L-, D- and DL-valine crystals

    NASA Astrophysics Data System (ADS)

    Segura, J. J.; Verdaguer, A.; Fraxedas, J.

    2014-03-01

    The adsorption of water on etched (001) surfaces of L-, D- and DL-valine crystals has been characterized by atomic force microscopy (AFM) using different operational modes (contact, non-contact and electrostatic) above and below the dew point, the temperature at which water vapor from humid air condenses into liquid water at constant atmospheric pressure. The analysis of the images suggests the formation of aggregates of solvated valine molecules that easily diffuse on the hydrophobic terraces only constrained by step barriers of the well-defined chiral parallelepipedic patterns induced by the etching process.

  12. Stereochemistry of valine biosynthesis. Configuration of the product of rearrangement of alpha-acetolactate.

    PubMed

    Crout, D H; Hedgecock, C J; Lipscomb, E L; Armstrong, F B

    1980-09-01

    When alpha-aceto[1,3,5-13C3]lactate (2-hydroxy-2-methyl-3-oxo[1,3,5-13C3]butanoate) was incubated with a cell-free system prepared from Salmonella typhimurium, the valine produced was labelled in the C-4 pro-S position. This result proves that during the tertiary ketol rearrangement catalysed by the reductoisomerase of the isoleucine-valine pathway, the methyl group transfer is to the re face of the trigonal centre at C-3 of alpha-acetolactate. PMID:7002550

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

    PubMed

    Holecek, Milan

    2010-05-01

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

  14. Branched-chain amino acid biosynthesis in Salmonella typhimurium: a quantitative analysis.

    PubMed

    Epelbaum, S; LaRossa, R A; VanDyk, T K; Elkayam, T; Chipman, D M; Barak, Z

    1998-08-01

    We report here the first quantitative study of the branched-chain amino acid biosynthetic pathway in Salmonella typhimurium LT2. The intracellular levels of the enzymes of the pathway and of the 2-keto acid intermediates were determined under various physiological conditions and used for estimation of several of the fluxes in the cells. The results led to a revision of previous ideas concerning the way in which multiple acetohydroxy acid synthase (AHAS) isozymes contribute to the fitness of enterobacteria. In wild-type LT2, AHAS isozyme I provides most of the flux to valine, leucine, and pantothenate, while isozyme II provides most of the flux to isoleucine. With acetate as a carbon source, a strain expressing AHAS II only is limited in growth because of the low enzyme activity in the presence of elevated levels of the inhibitor glyoxylate. A strain with AHAS I only is limited during growth on glucose by the low tendency of this enzyme to utilize 2-ketobutyrate as a substrate; isoleucine limitation then leads to elevated threonine deaminase activity and an increased 2-ketobutyrate/2-ketoisovalerate ratio, which in turn interferes with the synthesis of coenzyme A and methionine. The regulation of threonine deaminase is also crucial in this regard. It is conceivable that, because of fundamental limitations on the specificity of enzymes, no single AHAS could possibly be adequate for the varied conditions that enterobacteria successfully encounter. PMID:9696751

  15. Emerging Roles of Branched-Chain Amino Acid Supplementation in Human Diseases

    PubMed Central

    Tamanna, Nahid; Mahmood, Niaz

    2014-01-01

    The branched-chain amino acids (BCAAs), namely, valine, leucine, and isoleucine, are indispensable amino acids required for body protein synthesis. Unlike other amino acids, the BCAAs are primarily catabolised in the extrahepatic tissues. The BCAAs play role in regulation of protein synthesis and turnover as well as maintenance of the body glutamate-glutamine level. In strenuous and traumatic conditions, the BCAAs are oxidized which limits their availability in tissues. Such condition affects the body glutamate-glutamine pool and protein synthesis mechanisms. Thus BCCA supplementation is emerging as a nutritional strategy for treating many diseases. Many studies have found that BCAA administration is able to improve the health status of the patients suffering from different diseases even though there are conditions where they do not exert any effect. There are also some reports where elevated BCAAs have been shown to be associated with the pathogenesis of diseases. In this review, we have discussed the implication of BCAA supplementation in different pathological conditions and their relevant outcomes.

  16. Salmonella typhimurium mutants defective in acetohydroxy acid synthases I and II.

    PubMed

    Shaw, K J; Berg, C M; Sobol, T J

    1980-03-01

    An analysis of transposon-induced mutants shows that Salmonella typhimurium possesses two major isozymes of acetohydroxy acid synthase, the enzymes which mediate the first common step in isoleucine and valine biosynthesis. A third (minor) acetohydroxy acid synthase is present, but its significance in isoleucine and valine synthesis may be negligible. Mutants defective in acetohydroxy acid synthase II (ilvG::Tn10) require isoleucine, alpha-ketobutyrate, or threonine for growth, a mutant defective in acetohydroxy acid synthase I (ilvB::Tn5) is a prototroph, and a double mutant (ilvG::Tn10 ilvB::Tn5) requires isoleucine plus valine for growth. PMID:6245063

  17. A nuclear factor containing the leucine-rich repeats expressed in murine cerebellar neurons.

    PubMed Central

    Matsuoka, K; Taoka, M; Satozawa, N; Nakayama, H; Ichimura, T; Takahashi, N; Yamakuni, T; Song, S Y; Isobe, T

    1994-01-01

    A nuclear protein, termed leucine-rich acidic nuclear protein (LANP), has been isolated from among rat cerebellar proteins whose expression was transiently increased during an early stage of postnatal development. The amino acid sequence, deduced from its cDNA, showed that LANP contains 247 amino acids consisting of two distinct structural domains: the N-terminal domain characterized by "leucine-rich repeat," which is found in many eukaryotic proteins and which potentially functions in mediating protein-protein interactions, and the C-terminal domain characterized by a cluster of acidic amino acids with a putative nuclear localization signal. Immunohistochemical study using an antibody against LANP revealed that the protein is localized mainly in nuclei of Purkinje cells. In the rat cerebellum on postnatal day 7, LANP mRNA was expressed moderately in the external granule and Purkinje cells and weakly in the internal granule cells. The expression in these cells, especially in Purkinje cells, increased in the second postnatal week and thereafter decreased to an adult level. The structural characteristics, localization, and the stage- and cell type-specific expression suggest a potential role of LANP in a signal transduction pathway that directs differentiation of cerebellar neurons. Images PMID:7937870

  18. S-Isovaline Contained in Meteorites, Induces Enantiomeric Excess in D,L-glutamic Acid During Recrystallization

    NASA Astrophysics Data System (ADS)

    Kojo, Shosuke

    2015-06-01

    S-Isovaline (S-Iva: 6.7 mmol) and D,L-glutamic acid (Glu: 2 mmol) were dissolved in 10 ml of hot water, and the resulting solution was divided in 5 vessels. After recrystallization, the crystals were collected from each vessel, and the enantiomeric excess (ee) of Glu was determined with chemical derivatization using 1-fluoro-2,4-dinitrophenyl- 5-L-leucinamide followed by high-performance liquid chromatography. Ten crystallizations provided all D-rich Glu with ee values of 2.69 % ± 0.81 % (mean ± standard deviation), and those using R-Iva provided all L-rich Glu with ee values of 6.24 % ± 2.20 %. Five recrystallizations of D,L-Glu alone provided ee values of 0.474 % ± 0.33 %. The differences among these three ee values were statistically significant, showing that S-Iva, which was present in meteorites caused a significant induction of ee in this physiological amino acid. This is the first outcome that S-Iva induced ee changes in a physiological amino acid. S-Iva did not induce any ee changes in D,L-asparagine, leucine, valine, methionine, phenylalanine, tryptophan, glutamine, tyrosine, aspartic acid, or histidine under similar recrystallizations.

  19. S-Isovaline Contained in Meteorites, Induces Enantiomeric Excess in D,L-glutamic Acid During Recrystallization.

    PubMed

    Kojo, Shosuke

    2015-06-01

    S-Isovaline (S-Iva: 6.7 mmol) and D,L-glutamic acid (Glu: 2 mmol) were dissolved in 10 ml of hot water, and the resulting solution was divided in 5 vessels. After recrystallization, the crystals were collected from each vessel, and the enantiomeric excess (ee) of Glu was determined with chemical derivatization using 1-fluoro-2,4-dinitrophenyl- 5-L-leucinamide followed by high-performance liquid chromatography. Ten crystallizations provided all D-rich Glu with ee values of 2.69 % ± 0.81% (mean ± standard deviation), and those using R-Iva provided all L-rich Glu with ee values of 6.24 % ± 2.20%. Five recrystallizations of D,L-Glu alone provided ee values of 0.474 % ± 0.33%. The differences among these three ee values were statistically significant, showing that S-Iva, which was present in meteorites caused a significant induction of ee in this physiological amino acid. This is the first outcome that S-Iva induced ee changes in a physiological amino acid. S-Iva did not induce any ee changes in D,L-asparagine, leucine, valine, methionine, phenylalanine, tryptophan, glutamine, tyrosine, aspartic acid, or histidine under similar recrystallizations. PMID:25754590

  20. Impact of the N-terminal amino acid on the formation of pyrazines from peptides in Maillard model systems.

    PubMed

    Van Lancker, Fien; Adams, An; De Kimpe, Norbert

    2012-05-01

    Only a minor part of Maillard reaction studies in the literature focused on the reaction between carbohydrates and peptides. Therefore, in continuation of a previous study in which the influence of the peptide C-terminal amino acid was investigated, this study focused on the influence of the peptide N-terminal amino acid on the production of pyrazines in model reactions of glucose, methylglyoxal, or glyoxal. Nine different dipeptides and three tripeptides were selected. It was shown that the structure of the N-terminal amino acid is determinative for the overall pyrazine production. Especially, the production of 2,5(6)-dimethylpyrazine and trimethylpyrazine was low in the case of proline, valine, or leucine at the N-terminus, whereas it was very high for glycine, alanine, or serine. In contrast to the alkyl-substituted pyrazines, unsubstituted pyrazine was always produced more in the case of experiments with free amino acids. It is clear that different mechanisms must be responsible for this observation. This study clearly illustrates the capability of peptides to produce flavor compounds such as pyrazines. PMID:22463717

  1. Chiral separation of the clinically important compounds fucose and pipecolic acid using CE: determination of the most effective chiral selector.

    PubMed

    Hadjistasi, Christoforos A; Stavrou, Ioannis J; Stefan-Van Staden, Raluca-Ioana; Aboul-Enein, Hassan Y; Kapnissi-Christodoulou, Constantina P

    2013-09-01

    In this study, simple electrophoretic methods were developed for the chiral separation of the clinically important compounds fucose and pipecolic acid. In recent years, these analytes, and particularly their individual enantiomers, have attracted considerable attention due to their role in biological functions and disorders. The detectability and sensitivity of pipecolic acid and fucose were improved by reacting them with fluorenylmethyloxycarbonyl chloride (FMOC-Cl) and 5-amino-2-naphthalene-sulfonic acid (ANSA), respectively. The enantioseparation conditions were optimized by initially investigating the type of the chiral selector. Different chiral selectors, such as polymeric surfactants and cyclodextrins, were used and the most effective ones were determined with regard to resolution and analysis time. A 10-mM β-cyclodextrin was able to separate the enantiomers of ANSA-DL-fucose and the polymeric surfactant poly(sodium N-undecanoyl-LL-leucine-valinate) was able to separate the enantiomers of FMOC-DL-pipecolic acid, with resolution values of 3.45 and 2.78, respectively. Additional parameters, such as the concentration and the pH of the background electrolyte (BGE), the concentration of the chiral selector, and the addition of modifiers were examined in order to optimize the separations. The addition of the chiral ionic liquid D-alanine tert-butyl ester lactate into the BGE was also investigated, for the first time, in order to improve resolution of the enantiomers. PMID:23757267

  2. Application of self-organising maps towards segmentation of soybean samples by determination of amino acids concentration.

    PubMed

    Silva, Lívia Ramazzoti Chanan; Angilelli, Karina Gomes; Cremasco, Hágata; Romagnoli, Érica Signori; Galão, Olívio Fernandes; Borsato, Dionisio; Moraes, Larissa Alexandra Cardoso; Mandarino, José Marcos Gontijo

    2016-09-01

    Soybeans are widely used both for human nutrition and animal feed, since they are an important source of protein, and they also provide components such as phytosterols, isoflavones, and amino acids. In this study, were determined the concentrations of the amino acids lysine, histidine, arginine, asparagine, glutamic acid, glycine, alanine, valine, isoleucine, leucine, tyrosine, phenylalanine present in 14 samples of conventional soybeans and 6 transgenic, cultivated in two cities of the state of Paraná, Londrina and Ponta Grossa. The results were tabulated and presented to a self-organising map for segmentation according planting regions and conventional or transgenic varieties. A network with 7000 training epochs and a 10 × 10 topology was used, and it proved appropriate in the segmentation of the samples using the data analysed. The weight maps provided by the network, showed that all the amino acids were important in targeting the samples, especially isoleucine. Three clusters were formed, one with only Ponta Grossa samples (including transgenic (PGT) and common (PGC)), a second group with Londrina transgenic (LT) samples and the third with Londrina common (LC) samples. PMID:27213953

  3. GCN2 contributes to mTORC1 inhibition by leucine deprivation through an ATF4 independent mechanism.

    PubMed

    Averous, Julien; Lambert-Langlais, Sarah; Mesclon, Florent; Carraro, Valérie; Parry, Laurent; Jousse, Céline; Bruhat, Alain; Maurin, Anne-Catherine; Pierre, Philippe; Proud, Christopher G; Fafournoux, Pierre

    2016-01-01

    It is well known that the GCN2 and mTORC1 signaling pathways are regulated by amino acids and share common functions, in particular the control of translation. The regulation of GCN2 activity by amino acid availability relies on the capacity of GCN2 to sense the increased levels of uncharged tRNAs upon amino acid scarcity. In contrast, despite recent progress in the understanding of the regulation of mTORC1 by amino acids, key aspects of this process remain unsolved. In particular, while leucine is well known to be a potent regulator of mTORC1, the mechanisms by which this amino acid is sensed and control mTORC1 activity are not well defined. Our data establish that GCN2 is involved in the inhibition of mTORC1 upon leucine or arginine deprivation. However, the activation of GCN2 alone is not sufficient to inhibit mTORC1 activity, indicating that leucine and arginine exert regulation via additional mechanisms. While the mechanism by which GCN2 contributes to the initial step of mTORC1 inhibition involves the phosphorylation of eIF2α, we show that it is independent of the downstream transcription factor ATF4. These data point to a novel role for GCN2 and phosphorylation of eIF2α in the control of mTORC1 by certain amino acids. PMID:27297692

  4. GCN2 contributes to mTORC1 inhibition by leucine deprivation through an ATF4 independent mechanism

    PubMed Central

    Averous, Julien; Lambert-Langlais, Sarah; Mesclon, Florent; Carraro, Valérie; Parry, Laurent; Jousse, Céline; Bruhat, Alain; Maurin, Anne-Catherine; Pierre, Philippe; Proud, Christopher G.; Fafournoux, Pierre

    2016-01-01

    It is well known that the GCN2 and mTORC1 signaling pathways are regulated by amino acids and share common functions, in particular the control of translation. The regulation of GCN2 activity by amino acid availability relies on the capacity of GCN2 to sense the increased levels of uncharged tRNAs upon amino acid scarcity. In contrast, despite recent progress in the understanding of the regulation of mTORC1 by amino acids, key aspects of this process remain unsolved. In particular, while leucine is well known to be a potent regulator of mTORC1, the mechanisms by which this amino acid is sensed and control mTORC1 activity are not well defined. Our data establish that GCN2 is involved in the inhibition of mTORC1 upon leucine or arginine deprivation. However, the activation of GCN2 alone is not sufficient to inhibit mTORC1 activity, indicating that leucine and arginine exert regulation via additional mechanisms. While the mechanism by which GCN2 contributes to the initial step of mTORC1 inhibition involves the phosphorylation of eIF2α, we show that it is independent of the downstream transcription factor ATF4. These data point to a novel role for GCN2 and phosphorylation of eIF2α in the control of mTORC1 by certain amino acids. PMID:27297692

  5. l-Ala-γ-d-Glu-meso-diaminopimelic Acid (DAP) Interacts Directly with Leucine-rich Region Domain of Nucleotide-binding Oligomerization Domain 1, Increasing Phosphorylation Activity of Receptor-interacting Serine/Threonine-protein Kinase 2 and Its Interaction with Nucleotide-binding Oligomerization Domain 1*

    PubMed Central

    Laroui, Hamed; Yan, Yutao; Narui, Yoshie; Ingersoll, Sarah A.; Ayyadurai, Saravanan; Charania, Moiz A.; Zhou, Feimeng; Wang, Binghe; Salaita, Khalid; Sitaraman, Shanthi V.; Merlin, Didier

    2011-01-01

    The oligopeptide transporter PepT1 expressed in inflamed colonic epithelial cells transports small bacterial peptides, such as muramyl dipeptide (MDP) and l-Ala-γ-d-Glu-meso-diaminopimelic acid (Tri-DAP) into cells. The innate immune system uses various proteins to sense pathogen-associated molecular patterns. Nucleotide-binding oligomerization domain (NOD)-like receptors of which there are more than 20 related family members are present in the cytosol and recognize intracellular ligands. NOD proteins mediate NF-κB activation via receptor-interacting serine/threonine-protein kinase 2 (RICK or RIPK). The specific ligands for some NOD-like receptors have been identified. NOD type 1 (NOD1) is activated by peptides that contain a diaminophilic acid, such as the PepT1 substrate Tri-DAP. In other words, PepT1 transport activity plays an important role in controlling intracellular loading of ligands for NOD1 in turn determining the activation level of downstream inflammatory pathways. However, no direct interaction between Tri-DAP and NOD1 has been identified. In the present work, surface plasmon resonance and atomic force microscopy experiments showed direct binding between NOD1 and Tri-DAP with a Kd value of 34.5 μm. In contrast, no significant binding was evident between muramyl dipeptide and NOD1. Furthermore, leucine-rich region (LRR)-truncated NOD1 did not interact with Tri-DAP, indicating that Tri-DAP interacts with the LRR domain of NOD1. Next, we examined binding between RICK and NOD1 proteins and found that such binding was significant with a Kd value of 4.13 μm. However, NOD1/RICK binding was of higher affinity (Kd of 3.26 μm) when NOD1 was prebound to Tri-DAP. Furthermore, RICK phosphorylation activity was increased when NOD was prebound to Tri-DAP. In conclusion, we have shown that Tri-DAP interacts directly with the LRR domain of NOD1 and consequently increases RICK/NOD1 association and RICK phosphorylation activity. PMID:21757725

  6. Leucine metabolism regulates TRI6 expression and affects deoxynivalenol production and virulence in Fusarium graminearum.

    PubMed

    Subramaniam, Rajagopal; Narayanan, Swara; Walkowiak, Sean; Wang, Li; Joshi, Manisha; Rocheleau, Hélène; Ouellet, Thérèse; Harris, Linda J

    2015-11-01

    TRI6 is a positive regulator of the trichothecene gene cluster and the production of trichothecene mycotoxins [deoxynivalenol (DON)] and acetylated forms such as 15-Acetyl-DON) in the cereal pathogen Fusarium graminearum. As a global transcriptional regulator, TRI6 expression is modulated by nitrogen-limiting conditions, sources of nitrogen and carbon, pH and light. However, the mechanism by which these diverse environmental factors affect TRI6 expression remains underexplored. In our effort to understand how nutrients affect TRI6 regulation, comparative digital expression profiling was performed with a wild-type F. graminearum and a Δtri6 mutant strain, grown in nutrient-rich conditions. Analysis showed that TRI6 negatively regulates genes of the branched-chain amino acid (BCAA) metabolic pathway. Feeding studies with deletion mutants of MCC, encoding methylcrotonyl-CoA-carboxylase, one of the key enzymes of leucine metabolism, showed that addition of leucine specifically down-regulated TRI6 expression and reduced 15-ADON accumulation. Constitutive expression of TRI6 in the Δmcc mutant strain restored 15-ADON production. A combination of cellophane breach assays and pathogenicity experiments on wheat demonstrated that disrupting the leucine metabolic pathway significantly reduced disease. These findings suggest a complex interaction between one of the primary metabolic pathways with a global regulator of mycotoxin biosynthesis and virulence in F. graminearum. PMID:26248604

  7. Leucine supplementation improves regeneration of skeletal muscles from old rats.

    PubMed

    Pereira, Marcelo G; Silva, Meiricris T; da Cunha, Fernanda M; Moriscot, Anselmo S; Aoki, Marcelo S; Miyabara, Elen H

    2015-12-01

    The decreased regenerative capacity of old skeletal muscles involves disrupted turnover of proteins. This study investigated whether leucine supplementation in old rats could improve muscle regenerative capacity. Young and old male Wistar rats were supplemented with leucine; then, the muscles were cryolesioned and examined after 3 and 10 days. Leucine supplementation attenuated the decrease in the expression of eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1) and eukaryotic translation initiation factor 4E (eIF4E) in young and old muscles on day 3 post-injury and promoted an increase in the cross-sectional area of regenerating myofibers from both young and old soleus muscles on day 10 post-injury. This supplementation decreased the levels of ubiquitinated proteins and increased the proteasome activity in young regenerating muscles, but the opposite effect was observed in old regenerating muscles. Moreover, leucine decreased the inflammation area and induced an increase in the number of proliferating satellite cells in both young and old muscles. Our results suggest that leucine supplementation improves the regeneration of skeletal muscles from old rats, through the preservation of certain biological responses upon leucine supplementation. Such responses comprise the decrease in the inflammation area, increase in the number of proliferating satellite cells and size of regenerating myofibers, combined with the modulation of components of the phosphoinositide 3-kinase/Akt-protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway and ubiquitin-proteasome system. PMID:26481769

  8. Lysine and Leucine Deficiencies Affect Myocytes Development and IGF Signaling in Gilthead Sea Bream (Sparus aurata)

    PubMed Central

    Azizi, Sheida; Nematollahi, Mohammad Ali; Mojazi Amiri, Bagher; Vélez, Emilio J.; Lutfi, Esmail; Navarro, Isabel; Capilla, Encarnación; Gutiérrez, Joaquim

    2016-01-01

    Optimizing aquaculture production requires better knowledge of growth regulation and improvement in diet formulation. A great effort has been made to replace fish meal for plant protein sources in aquafeeds, making necessary the supplementation of such diets with crystalline amino acids (AA) to cover the nutritional requirements of each species. Lysine and Leucine are limiting essential AA in fish, and it has been demonstrated that supplementation with them improves growth in different species. However, the specific effects of AA deficiencies in myogenesis are completely unknown and have only been studied at the level of hepatic metabolism. It is well-known that the TOR pathway integrates the nutritional and hormonal signals to regulate protein synthesis and cell proliferation, to finally control muscle growth, a process also coordinated by the expression of myogenic regulatory factors (MRFs). This study aimed to provide new information on the impact of Lysine and Leucine deficiencies in gilthead sea bream cultured myocytes examining their development and the response of insulin-like growth factors (IGFs), MRFs, as well as key molecules involved in muscle growth regulation like TOR. Leucine deficiency did not cause significant differences in most of the molecules analyzed, whereas Lysine deficiency appeared crucial in IGFs regulation, decreasing significantly IGF-I, IGF-II and IGF-IRb mRNA levels. This treatment also down-regulated the gene expression of different MRFs, including Myf5, Myogenin and MyoD2. These changes were also corroborated by a significant decrease in proliferation and differentiation markers in the Lysine-deficient treatment. Moreover, both Lysine and Leucine limitation induced a significant down-regulation in FOXO3 gene expression, which deserves further investigation. We believe that these results will be relevant for the production of a species as appreciated for human consumption as it is gilthead sea bream and demonstrates the importance of

  9. Relations among arginine, citrulline, ornithine, and leucine kinetics in adult burn patients.

    PubMed

    Yu, Y M; Ryan, C M; Burke, J F; Tompkins, R G; Young, V R

    1995-11-01

    Plasma fluxes of arginine, citrulline, and leucine, and the rate of conversion of labeled citrulline to arginine (Qcit-->arg) were determined in nine severely burned patients (mean: 56% body surface burn area, mean 10 d postinjury) while they received total parenteral nutrition (TPN) including an L-amino acid mixture that supplied a generous amount of nitrogen (mean: 0.39 +/- 0.02 g.kg-1.d-1). Plasma fluxes were also studied in these patients during a basal state (low-dose intravenous glucose) by using a primed, 4-h constant intravenous tracer-infusion protocol. Stable-nuclide labeled tracers were L-[15N-15N-guanidino,5,5,2H2]arginine; L-[13C-ureido]citrulline; L-[1-13C]leucine; and NaH13CO3 (prime only), with blood and expired air samples drawn at intervals to determine isotopic abundance of arginine, citrulline, ornithine, and alpha-ketoisocaproate (KIC; for leucine) in plasma and 13CO2 in breath. Leucine kinetics (flux and disappearance into protein synthesis) confirmed the anticipated higher protein turnover in these burn patients compared with healthy control subjects. The plasma arginine fluxes were correspondingly higher in burn patients than in healthy control subjects. However, the citrulline flux and rate of conversion of citrulline to arginine were not higher than values obtained in our laboratories in healthy adult subjects. We hypothesize that the higher rates of arginine loss from the body after burn injury would need to be balanced by an appropriate exogenous intake of preformed arginine to maintain protein homeostasis and promote recovery from this catabolic condition. PMID:7572742

  10. Structural and functional evolution of isopropylmalate dehydrogenases in the leucine and glucosinolate pathways of Arabidopsis thaliana

    SciTech Connect

    He, Yan; Galant, Ashley; Pang, Qiuying; Strul, Johanna M.; Balogun, Sherifat F.; Jez, Joseph M.; Chen, Sixue

    2012-10-24

    The methionine chain-elongation pathway is required for aliphatic glucosinolate biosynthesis in plants and evolved from leucine biosynthesis. In Arabidopsis thaliana, three 3-isopropylmalate dehydrogenases (AtIPMDHs) play key roles in methionine chain-elongation for the synthesis of aliphatic glucosinolates (e.g. AtIPMDH1) and leucine (e.g. AtIPMDH2 and AtIPMDH3). Here we elucidate the molecular basis underlying the metabolic specialization of these enzymes. The 2.25 {angstrom} resolution crystal structure of AtIPMDH2 was solved to provide the first detailed molecular architecture of a plant IPMDH. Modeling of 3-isopropylmalate binding in the AtIPMDH2 active site and sequence comparisons of prokaryotic and eukaryotic IPMDH suggest that substitution of one active site residue may lead to altered substrate specificity and metabolic function. Site-directed mutagenesis of Phe-137 to a leucine in AtIPMDH1 (AtIPMDH1-F137L) reduced activity toward 3-(2'-methylthio)ethylmalate by 200-fold, but enhanced catalytic efficiency with 3-isopropylmalate to levels observed with AtIPMDH2 and AtIPMDH3. Conversely, the AtIPMDH2-L134F and AtIPMDH3-L133F mutants enhanced catalytic efficiency with 3-(2'-methylthio)ethylmalate {approx}100-fold and reduced activity for 3-isopropylmalate. Furthermore, the altered in vivo glucosinolate profile of an Arabidopsis ipmdh1 T-DNA knock-out mutant could be restored to wild-type levels by constructs expressing AtIPMDH1, AtIPMDH2-L134F, or AtIPMDH3-L133F, but not by AtIPMDH1-F137L. These results indicate that a single amino acid substitution results in functional divergence of IPMDH in planta to affect substrate specificity and contributes to the evolution of specialized glucosinolate biosynthesis from the ancestral leucine pathway.

  11. Site reactivity in the free radicals induced damage to leucine residues: a theoretical study.

    PubMed

    Medina, M E; Galano, A; Alvarez-Idaboy, J R

    2015-02-21

    Several recent computational studies have tried to explain the observed selectivity in radical damage to proteins. In this work we use Density Functional Theory and Transition State Theory including tunnelling corrections, reaction path degeneracy, the effect of diffusion, and the role of free radicals to get further insights into this important topic. The reaction between a leucine derivative and free radicals of biological significance, in aqueous and lipid media, has been investigated. Both thermochemical and kinetic analyses, in both hydrophilic and hydrophobic environments, have been carried out. DPPH, ˙OOH, ˙OOCH3, ˙OOCH2Cl, ˙OOCHCl2 and ˙OOCHCH2 radicals do not react with the target molecule. The reactions are proposed to be kinetically controlled. The leucine gamma site was the most reactive for the reactions with ˙N3, ˙OOCCl3, ˙OCH3, ˙OCH2Cl, and ˙OCHCl2 radicals, with rate constants equal to 1.97 × 10(5), 3.24 × 10(4), 6.68 × 10(5), 5.98 × 10(6) and 8.87 × 10(8) M(-1) s(-1), respectively, in aqueous solution. The ˙Cl, ˙OH and ˙OCCl3 radicals react with leucine at the beta, gamma, and delta positions at rates close to the diffusion limit with the alpha position which is the slowest path and the most thermodynamically favored. The presented results confirm that the Bell-Evans-Polanyi principle does not apply for the reactions between amino acid residues and free radicals. Regarding the influence of the environment on the reactivity of the studied series of free radicals towards leucine residues, it is concluded that hydrophilic media slightly lower the reactivity of the studied radicals, compared to hydrophobic ones, albeit the trends in reactivity are very similar. PMID:25592549

  12. Distribution and Evolution of Yersinia Leucine-Rich Repeat Proteins.

    PubMed

    Hu, Yueming; Huang, He; Hui, Xinjie; Cheng, Xi; White, Aaron P; Zhao, Zhendong; Wang, Yejun

    2016-08-01

    Leucine-rich repeat (LRR) proteins are widely distributed in bacteria, playing important roles in various protein-protein interaction processes. In Yersinia, the well-characterized type III secreted effector YopM also belongs to the LRR protein family and is encoded by virulence plasmids. However, little has been known about other LRR members encoded by Yersinia genomes or their evolution. In this study, the Yersinia LRR proteins were comprehensively screened, categorized, and compared. The LRR proteins encoded by chromosomes (LRR1 proteins) appeared to be more similar to each other and different from those encoded by plasmids (LRR2 proteins) with regard to repeat-unit length, amino acid composition profile, and gene expression regulation circuits. LRR1 proteins were also different from LRR2 proteins in that the LRR1 proteins contained an E3 ligase domain (NEL domain) in the C-terminal region or an NEL domain-encoding nucleotide relic in flanking genomic sequences. The LRR1 protein-encoding genes (LRR1 genes) varied dramatically and were categorized into 4 subgroups (a to d), with the LRR1a to -c genes evolving from the same ancestor and LRR1d genes evolving from another ancestor. The consensus and ancestor repeat-unit sequences were inferred for different LRR1 protein subgroups by use of a maximum parsimony modeling strategy. Structural modeling disclosed very similar repeat-unit structures between LRR1 and LRR2 proteins despite the different unit lengths and amino acid compositions. Structural constraints may serve as the driving force to explain the observed mutations in the LRR regions. This study suggests that there may be functional variation and lays the foundation for future experiments investigating the functions of the chromosomally encoded LRR proteins of Yersinia. PMID:27217422

  13. Electrophysiological evidence for acidic, basic, and neutral amino acid olfactory receptor sites in the catfish.

    PubMed

    Caprio, J; Byrd, R P

    1984-09-01

    Electrophysiological experiments indicate that olfactory receptors of the channel catfish, Ictalurus punctatus, contain different receptor sites for the acidic (A), basic (B), and neutral amino acids; further, at least two partially interacting neutral sites exist, one for the hydrophilic neutral amino acids containing short side chains (SCN), and the second for the hydrophobic amino acids containing long side chains (LCN). The extent of cross-adaptation was determined by comparing the electro-olfactogram (EOG) responses to 20 "test" amino acids during continuous bathing of the olfactory mucosa with water only (control) to those during each of the eight "adapting" amino acid regimes. Both the adapting and test amino acids were adjusted in concentrations to provide approximately equal response magnitudes in the unadapted state. Under all eight adapting regimes, the test EOG responses were reduced from those obtained in the unadapted state, but substantial quantitative differences resulted, depending upon the molecular structure of the adapting stimulus. Analyses of the patterns of EOG responses to the test stimuli identified and characterized the respective "transduction processes," a term used to describe membrane events initiated by a particular subset of amino acid stimuli that are intricately linked to the origin of the olfactory receptor potential. Only when the stimulus compounds interact with different transduction processes are the stimuli assumed to bind to different membrane "sites." Four relatively independent L-alpha-amino acid transduction processes (and thus at least four binding sites) identified in this report include: (a) the A process for aspartic and glutamic acids; (b) the B process for arginine and lysine; (c) the SCN process for glycine, alanine, serine, glutamine, and possibly cysteine; (d) the LCN process for methionine, ethionine, valine, norvaline, leucine, norleucine, glutamic acid-gamma-methyl ester, histidine, phenylalanine, and also

  14. Diet quality influences isotopic discrimination among amino acids in an aquatic vertebrate.

    PubMed

    Chikaraishi, Yoshito; Steffan, Shawn A; Takano, Yoshinori; Ohkouchi, Naohiko

    2015-05-01

    Stable nitrogen isotopic composition of amino acids (δ (15)NAA) has recently been employed as a powerful tool in ecological food web studies, particularly for estimating the trophic position (TP) of animal species in food webs. However, the validity of these estimates depends on the consistency of the trophic discrimination factor (TDF; - Δδ (15)NAA at each shift of trophic level) among a suite of amino acids within the tissues of consumer species. In this study, we determined the TDF values of amino acids in tadpoles (the Japanese toad, Bufo japonicus) reared exclusively on one of three diets that differed in nutritional quality. The diets were commercial fish-food pellets (plant and animal biomass), bloodworms (animal biomass), and boiled white rice (plant carbohydrate), representing a balanced, protein-rich, and protein-poor diet, respectively. The TDF values of two "source amino acids" (Src-AAs), methionine and phenylalanine, were close to zero (0.3-0.5‰) among the three diets, typifying the values reported in the literature (∼0.5‰ and ∼0.4‰, respectively). However, TDF values of "trophic amino acids" (Tr-AAs) including alanine, valine, leucine, isoleucine, and glutamic acid varied by diet: for example, the glutamic acid TDF was similar to the standard value (∼8.0‰) when tadpoles were fed either the commercial pellets (8.0‰) or bloodworms (7.9‰), but when they were fed boiled rice, the TDF was significantly reduced (0.6‰). These results suggest that a profound lack of dietary protein may alter the TDF values of glutamic acid (and other Tr-AAs and glycine) within consumer species, but not the two Src-AAs (i.e., methionine and phenylalanine). Knowledge of how a nutritionally poor diet can influence the TDF of Tr- and Src-AAs will allow amino acid isotopic analyses to better estimate TP among free-roaming animals. PMID:26045955

  15. Docosahexaenoic acid status in females of reproductive age with maple syrup urine disease.

    PubMed

    Mazer, Laura M; Yi, Sarah H L; Singh, Rani H

    2010-04-01

    Individuals with maple syrup urine disease (MSUD) have impaired metabolism of branched-chain amino acids (BCAA) valine, isoleucine, and leucine. Life-long dietary therapy is recommended to restrict BCAA intake and thus prevent poor neurological outcomes and death. To maintain adequate nutritional status, the majority of protein and nutrients are derived from synthetic BCAA-free medical foods with variable fatty acid content. Given the restrictive diet and the importance of omega-3 fatty acids, particularly docosahexaenoic acid (DHA), in neurological development, this study evaluated the dietary and fatty acid status of females of reproductive age with MSUD attending a metabolic camp. Healthy controls of similar age and sex were selected from existing normal laboratory data. Total lipid fatty acid concentration in plasma and erythrocytes was analyzed using gas chromatography-mass spectroscopy. Participants with MSUD had normal to increased concentrations of plasma and erythrocyte alpha linolenic acid (ALA) but significantly lower concentrations of plasma and erythrocyte docosahexaenoic acid (DHA) as percent of total lipid fatty acids compared with controls (plasma DHA: MSUD 1.03 +/- 0.35, controls 2.87 +/- 1.08; P = 0.001; erythrocyte DHA: MSUD 2.58 +/- 0.58, controls 3.66 +/- 0.80; P = 0.011). Dietary records reflected negligible or no DHA intake over the 3-day period prior to the blood draw (range 0-2 mg). These results suggest females of reproductive age with MSUD have lower blood DHA concentrations than age-matched controls. In addition, the presence of ALA in medical foods and the background diet may not counter the lack of preformed DHA in the diet. The implications of these results warrant further investigation. PMID:20217236

  16. 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.

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

    PubMed

    Imanari, M; Kadowaki, M; Fujimura, S

    2008-05-01

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

  18. Spin-trap-radical chromatography of spin adducts produced from L-valine by. gamma. -irradiation

    SciTech Connect

    Makiino, K.; Suzuki, N.; Moriya, F.; Rokushika, S.; Hatano, H.

    1980-01-01

    Diastereomeric spin adducts produced by reaction of 2-methyl-2-nitrosopropane with the short-lived radicals from L-valine by ..gamma..-irradiation could be separated and identified by means of high performance liquid chromatography and ESR spectroscopy. 6 figures.

  19. Biosensor-driven adaptive laboratory evolution of l-valine production in Corynebacterium glutamicum.

    PubMed

    Mahr, Regina; Gätgens, Cornelia; Gätgens, Jochem; Polen, Tino; Kalinowski, Jörn; Frunzke, Julia

    2015-11-01

    Adaptive laboratory evolution has proven a valuable strategy for metabolic engineering. Here, we established an experimental evolution approach for improving microbial metabolite production by imposing an artificial selective pressure on the fluorescent output of a biosensor using fluorescence-activated cell sorting. Cells showing the highest fluorescent output were iteratively isolated and (re-)cultivated. The L-valine producer Corynebacterium glutamicum ΔaceE was equipped with an L-valine-responsive sensor based on the transcriptional regulator Lrp of C. glutamicum. Evolved strains featured a significantly higher growth rate, increased L-valine titers (~25%) and a 3-4-fold reduction of by-product formation. Genome sequencing resulted in the identification of a loss-of-function mutation (UreD-E188*) in the gene ureD (urease accessory protein), which was shown to increase L-valine production by up to 100%. Furthermore, decreased L-alanine formation was attributed to a mutation in the global regulator GlxR. These results emphasize biosensor-driven evolution as a straightforward approach to improve growth and productivity of microbial production strains. PMID:26453945

  20. The optimum dietary indispensable amino acid pattern for growing Atlantic salmon (Salmo salar L.) fry.

    PubMed

    Rollin, Xavier; Mambrini, Muriel; Abboudi, Tarik; Larondelle, Yvan; Kaushik, Sadasivam J

    2003-11-01

    To determine the optimum indispensable (I) amino acid (AA) balance in Atlantic salmon (Salmo salar L.) fry, a single protocol established for the pig was adapted. The balance was calculated from the reduction in N gain after replacing about 45% of a single IAA by a mixture of dispensable AA in isonitrogenous diets. We confirmed that the mixture of AA simulating the AA pattern of cod-meal protein and gelatine (46:3, w/w) was used with the same efficiency as cod-meal protein and gelatine. From the deletion experiment an optimum balance between the IAA was derived. Expressed relative to lysine = 100, the optimal balance was: arginine 76 (SE 0.2), histidine 28 (SE 2.2), methionine + cystine 64 (SE 1.7), phenylalanine + tyrosine 105 (SE 1.6), threonine 51 (SE 2.4), tryptophan 14 (SE 0.7), valine 59 (SE 1.7). No estimates were made for isoleucine and leucine. Expressed as g/16 g N, the optimal balance was: arginine 4.0 (SE 0.0), histidine 1.5 (SE 0.1), lysine 5.3 (SE 0.2), methionine + cystine 3.4 (SE 0.1), phenylaline + tyrosine 5.6 (SE 0.1), threonine 2.7 (SE 0.1), tryptophan 0.7 (SE 0.0), valine 3.1 (SE 0.1). This AA composition is close to that of the Atlantic salmon whole-body, but using it as an estimation of the IAA requirements may lead to an overestimation of the branched-chain AA requirements and an underestimation of aromatic and S-containing AA requirements. The results are discussed in accordance with the key assumptions associated with the model used (broken-line model, IAA efficiencies and maintenance requirements). PMID:14667180

  1. Free amino acids in atmospheric particulate matter of Venice, Italy

    NASA Astrophysics Data System (ADS)

    Barbaro, Elena; Zangrando, Roberta; Moret, Ivo; Barbante, Carlo; Cescon, Paolo; Gambaro, Andrea

    2011-09-01

    The concentrations of free amino acids were determined in atmospheric particulate matter from the city of Venice (Italy) in order to better understand their origin. The analysis of aerosol samples was carried out via high-performance liquid chromatography coupled to a triple quadrupole tandem mass spectrometric detector (HPLC/ESI-MS/MS). The internal standard method was used and the analytical procedure was validated by evaluating the trueness, the precision, the recovery, the detection and the quantification limits. The particulate matter was collected using quartz fiber filters and extracted in methanol; after filtration the extract was directly analyzed. Forty samples were collected from April to October 2007 and the average concentrations of free amino acids in the aerosol were: alanine 35.6 pmol m -3, aspartic acid 31.1 pmol m -3, glycine 30.1 pmol m -3, glutamic acid 32.5 pmol m -3, isoleucine 2.4 pmol m -3, leucine 2.7 pmol m -3, methionine, cystine and 3-hydroxy-proline below the limit of detection, phenylalanine 2.8 pmol m -3, proline 43.3 pmol m -3, serine 8.6 pmol m -3, threonine 2.8 pmol m -3, tyrosine 1.7 pmolm -3, valine 3.8 pmol m -3, asparagine 70.2 pmol m -3, glutamine 38.0 pmol m -3, 4-hydroxy-proline 2.5 pmol m -3, methionine sulfoxide 1.1 pmol m -3, and methionine sulfone 0.1 pmol m -3. The total average concentration of these free amino acids in aerosol samples of Venice Lagoon was 334 pmol m -3. The temporal evolution and multivariate analysis indicated the photochemical origin of 4-hydroxy-proline and methionine sulfoxide and for other compounds an origin further away from the site of sampling, presumably reflecting transport from terrestrial sources.

  2. Genetics Home Reference: maple syrup urine disease

    MedlinePlus

    ... is unable to process certain protein building blocks (amino acids) properly. The condition gets its name from the ... protein complex is essential for breaking down the amino acids leucine, isoleucine, and valine, which are present in ...

  3. Genetics Home Reference: dihydrolipoamide dehydrogenase deficiency

    MedlinePlus

    ... in the breakdown of three protein building blocks (amino acids) commonly found in protein-rich foods: leucine, isoleucine, and valine. Breakdown of these amino acids produces molecules that can be used for energy. ...

  4. The stability constants of copper(II) complexes with some alpha-amino acids in dioxan-water mixtures.

    PubMed

    Doğan, A; Köseoğlu, F; Kiliç, E

    2001-08-15

    In this study, the overall stability constants of copper(II) complexes with some alpha-amino acids (glycine, dl-alanine, dl-valine, l-leucine, l-asparagine, l-glutamine) were determined by potentiometric titration in water, 25% dioxan-75% water, 35% dioxan-65% water, 50% dioxan-50% water, and 60% dioxan-40% water. The titrations were performed at 25 degrees C, under nitrogen atmosphere, and the ionic strength of the medium was maintained at 0.10 M by using sodium perchlorate. The formation curves of their complexes (n-p[L]) were obtained by means of the titration data. Then the stability constants were determined in relation to these curves. The mol ratio of copper(II) to alpha-amino acid was also determined and it was found that the complexes were CuL(2) type. Another important result obtained was that the tendency of amino acids to form complexes with copper(II) was greater in dioxan-water mixtures compared to water. PMID:11488627

  5. Recombinant polycistronic structure of hydantoinase process genes in Escherichia coli for the production of optically pure D-amino acids.

    PubMed

    Martínez-Gómez, Ana Isabel; Martínez-Rodríguez, Sergio; Clemente-Jiménez, Josefa María; Pozo-Dengra, Joaquín; Rodríguez-Vico, Felipe; Las Heras-Vázquez, Francisco Javier

    2007-03-01

    Two recombinant reaction systems for the production of optically pure D-amino acids from different D,L-5-monosubstituted hydantoins were constructed. Each system contained three enzymes, two of which were D-hydantoinase and D-carbamoylase from Agrobacterium tumefaciens BQL9. The third enzyme was hydantoin racemase 1 for the first system and hydantoin racemase 2 for the second system, both from A. tumefaciens C58. Each system was formed by using a recombinant Escherichia coli strain with one plasmid harboring three genes coexpressed with one promoter in a polycistronic structure. The D-carbamoylase gene was cloned closest to the promoter in order to obtain the highest level of synthesis of the enzyme, thus avoiding intermediate accumulation, which decreases the reaction rate. Both systems were able to produce 100% conversion and 100% optically pure D-methionine, D-leucine, D-norleucine, D-norvaline, D-aminobutyric acid, D-valine, D-phenylalanine, D-tyrosine, and D-tryptophan from the corresponding hydantoin racemic mixture. For the production of almost all D-amino acids studied in this work, system 1 hydrolyzed the 5-monosubstituted hydantoins faster than system 2. PMID:17220246

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

    PubMed

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

    2013-04-01

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

  7. High-Resolution Electrospray Ionization/Ion Mobility Spectrometer for Detection of Abiotic Amino Acids

    NASA Technical Reports Server (NTRS)

    Beegle, L. W.; Terrell, C. A.; Kim, H.; Kanik, I.

    2003-01-01

    One of the primary goals of the current NASA thrust in Astrobiology is the detection and identification of organic molecules as part of an in-situ lander platform on the surface of Mars or Europa. The identification of these molecules should help determine whether indigenous organisms exist on the surface of Mars or in an undersea environment on Europa. In addition, a detailed organic chemical inventory of surface and near surface molecules will help elucidate the possibilities of life elsewhere in the Universe. Terrestrial life has, as its backbone, the family of molecules known as the amino acids (AA), and while AA can be found in the terrestrial environments as part of more complex molecules, such as peptides, and proteins, they also exist as individual molecules due to of the hydrolyses of biopolymers. In terrestrial biochemistry, there are 20 principal amino acids which are necessary for life. However, some forms of these molecules can be found in nature synthesized via abiotic process. For example, they are known to exist extraterrestrially as a component of carbonaceous meteorites. The idea that amino acids are readily created by abiotic means has been demonstrated by their positive identification in the Murchison CM2 meteorite, which fell in 1969. This meteorite was analyzed before contamination by terrestrial microbes could result. Three laboratories individually tested parts of the meteorite and concluded that the amino acids present in them were indigenous to the meteorite because, among other reasons, they had equal L- and D- enantiomers. Final identification of the constituents of the Murchison included 33 amino acids which have no known biotic source, 11 amino acids which have limited distribution and 8 (Glycine, Alanine, Valine, Proline, Leucine, Isoleucine, Aspartic Acid, and Glutamic Acid), which readily occur in terrestrial proteins.

  8. Polymers from amino acids: development of dual ester-urethane melt condensation approach and mechanistic aspects.

    PubMed

    Anantharaj, S; Jayakannan, M

    2012-08-13

    A new dual ester-urethane melt condensation methodology for biological monomers-amino acids was developed to synthesize new classes of thermoplastic polymers under eco-friendly and solvent-free polymerization approach. Naturally abundant L-amino acids were converted into dual functional ester-urethane monomers by tailor-made synthetic approach. Direct polycondensation of these amino acid monomers with commercial diols under melt condition produced high molecular weight poly(ester-urethane)s. The occurrence of the dual ester-urethane process and the structure of the new poly(ester-urethane)s were confirmed by (1)H and (13)C NMR. The new dual ester-urethane condensation approach was demonstrated for variety of amino acids: glycine, β-alanine, L-alanine, L-leucine, L-valine, and L-phenylalanine. MALDI-TOF-MS end group analysis confirmed that the amino acid monomers were thermally stable under the melt polymerization condition. The mechanism of melt process and the kinetics of the polycondensation were studied by model reactions and it was found that the amino acid monomer was very special in the sense that their ester and urethane functionality could be selectively reacted by polymerization temperature or catalyst. The new polymers were self-organized as β-sheet in aqueous or organic solvents and their thermal properties such as glass transition temperature and crystallinity could be readily varied using different l-amino acid monomers or diols in the feed. Thus, the current investigation opens up new platform of research activates for making thermally stable and renewable engineering thermoplastics from natural resource amino acids. PMID:22713137

  9. 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.

  10. Acetohydroxy acid synthase isoenzymes of Escherichia coli K12 and Salmonella typhimurium.

    PubMed

    de Felice, M; Lago, C T; Squires, C H; Calvo, J M

    1982-01-01

    In Escherichia coli K12 and in Salmonella typhimurium the first step common to the biosynthesis of isoleucine, leucine and valine is catalyzed by an intriguing system of isoenzymes. Two of these are normally expressed, while the genetic determinant for a third one is transcribed, but not translated as an active polypeptide. We analyze here the significance of this system in the light of the most recent results. PMID:6805381

  11. Consequences of Alteration in Leucine Zipper Sequence of Melittin in Its Neutralization of Lipopolysaccharide-induced Proinflammatory Response in Macrophage Cells and Interaction with Lipopolysaccharide*

    PubMed Central

    Srivastava, Raghvendra M.; Srivastava, Saurabh; Singh, Manish; Bajpai, Virendra Kumar; Ghosh, Jimut Kanti

    2012-01-01

    The bee venom antimicrobial peptide, melittin, besides showing versatile activity against microorganisms also neutralizes lipopolysaccharide (LPS)-induced proinflammatory responses in macrophage cells. However, how the amino acid sequence of melittin contributes in its anti-inflammatory properties is mostly unknown. To determine the importance of the leucine zipper sequence of melittin in its neutralization of LPS-induced inflammatory responses in macrophages and interaction with LPS, anti-inflammatory properties of melittin and its three analogues and their interactions with LPS were studied in detail. Two of these analogues, namely melittin Mut-1 (MM-1) and melittin Mut-2 (MM-2), possess leucine to alanine substitutions in the single and double heptadic leucine residue(s) of melittin, respectively, whereas the third analogue is a scrambled peptide (Mel-SCR) that contains the amino acid composition of melittin with minor rearrangement in its leucine zipper sequence. Although MM-1 partly inhibited the production of proinflammatory cytokines in RAW 264.7 and rat primary macrophage cells in the presence of LPS, MM-2 and Mel-SCR were negligibly active. A progressive decrease in interaction of melittin with LPS, aggregation in LPS, and dissociation of LPS aggregates with alteration in the leucine zipper sequence of melittin was observed. Furthermore, with alteration in the leucine zipper sequence of melittin, these analogues failed to exhibit cellular responses associated with neutralization of LPS-induced inflammatory responses in macrophage cells by melittin. The data indicated a probable important role of the leucine zipper sequence of melittin in neutralizing LPS-induced proinflammatory responses in macrophage cells as well as in its interaction with LPS. PMID:22128186

  12. Metabolic engineering of valine- and isoleucine-derived glucosinolates in Arabidopsis expressing CYP79D2 from Cassava.

    PubMed

    Mikkelsen, Michael Dalgaard; Halkier, Barbara Ann

    2003-02-01

    Glucosinolates are amino acid-derived natural products that, upon hydrolysis, typically release isothiocyanates with a wide range of biological activities. Glucosinolates play a role in plant defense as attractants and deterrents against herbivores and pathogens. A key step in glucosinolate biosynthesis is the conversion of amino acids to the corresponding aldoximes, which is catalyzed by cytochromes P450 belonging to the CYP79 family. Expression of CYP79D2 from cassava (Manihot esculenta Crantz.) in Arabidopsis resulted in the production of valine (Val)- and isoleucine-derived glucosinolates not normally found in this ecotype. The transgenic lines showed no morphological phenotype, and the level of endogenous glucosinolates was not affected. The novel glucosinolates were shown to constitute up to 35% of the total glucosinolate content in mature rosette leaves and up to 48% in old leaves. Furthermore, at increased concentrations of these glucosinolates, the proportion of Val-derived glucosinolates decreased. As the isothiocyanates produced from the Val- and isoleucine-derived glucosinolates are volatile, metabolically engineered plants producing these glucosinolates have acquired novel properties with great potential for improvement of resistance to herbivorous insects and for biofumigation. PMID:12586901

  13. Method development for the determination of D- and L-isomers of leucine in human plasma by high-performance liquid chromatography tandem mass spectrometry and its application to animal plasma samples.

    PubMed

    Sugimoto, Hiroshi; Kakehi, Masaaki; Jinno, Fumihiro

    2015-10-01

    We developed a highly sensitive and specific high-performance liquid chromatography tandem mass spectrometry method with an electrospray ionization for the determination of D- and L-isomers of leucine in human plasma. Phosphate-buffered saline was used as the surrogate matrix for preparation of calibration curves and quality control samples. The extraction of D- and L-leucine in plasma samples (100 μL) was performed using cationic exchange solid-phase extraction. The enantiomer separation of D- and L-leucine was successfully achieved without derivatization using a CHIRALPAK ZWIX(-) with an isocratic mobile phase comprised of methanol/acetonitrile/1 mol/L ammonium formate/formic acid (500:500:25:2, v/v/v/v) at a flow rate of 0.5 mL/min. In addition, the discrimination of DL-leucine from structural isomers DL-isoleucine and DL-allo-isoleucine was performed using the unique precursor and product ion pair transition of DL-leucine (m/z 132.1 > 43.0) and DL-leucine-d 7 (m/z 139.2 > 93.0) in positive electrospray ionization mode. The standard curves were linear throughout the calibration range from 0.001 to 1 μg/mL for D-leucine and from 1 to 1000 μg/mL for L-leucine, respectively, with acceptable intra- and inter-day precision and accuracy. The stability of D- and L-leucine in human plasma and solvents was confirmed. The endogenous level of D- and L-leucine in human plasma was 0.00197~0.00591 and 9.63~24.7 μg/mL, respectively. This method was also successfully applied to investigate the species difference in the ratios of D-leucine to total leucine from individual plasma concentrations in humans and various animals. The plasma D-leucine concentrations or their ratio to total leucine in rodents was much higher than that in humans. PMID:26345443

  14. Olfactory discrimination of amino acids in brown bullhead catfish.

    PubMed

    Valentincic, T; Metelko, J; Ota, D; Pirc, V; Blejec, A

    2000-02-01

    Olfactory discrimination of amino acids was investigated in brown bullhead catfish (Ameiurus nebulosus). Based on the magnitude of the observed food search activity of catfish conditioned to single amino acids, the tested compounds were classified as being detected by the catfish as equal to, similar to, or different from the conditioned stimulus. L-Proline (L-Pro)-conditioned brown bullhead catfish discriminated all amino acids from L-Pro, but catfish conditioned to L-valine (L-Val) and L-isoleucine (L-Ile) did not discriminate L-Val from L-Ile nor L-Ile from L-Val; however, all other amino acids tested were always discriminated from these two compounds. Catfish conditioned to L-alanine (L-Ala) discriminated basic, acidic and several neutral amino acids with long side-chains (LCNs) from L-Ala; however, they did not always discriminate L-Ala from all neutral amino acids with short side-chains (SCNs). The L-norleucine (L-nLeu)-conditioned fish responded to L-norvaline (L-nVal), L-methionine (L-Met) and L-Ala similarly to L-nLeu, indicating that these amino acids are detected as similar or identical to L-nLeu. L-nLeu was, however, discriminated from L-Ala in L-Ala-conditioned catfish. Interestingly, L-leucine (L-Leu) was discriminated from the conditioned stimuli, L-Ala, L-Ile and L-Val, indicating independent receptors for L-Leu. Although conditioned catfish discriminated other amino acids from L-arginine hydrochloride (L-Arg), in some tests they were unable to discriminate L-Arg from L-lysine hydrochloride (L-Lys). These results imply the existence of independent olfactory receptive pathways for: (i) L-Pro; (ii) basic amino acids (L-Arg and L-Lys); (iii) L-Leu; (iv) other neutral amino acids with branched side-chains (L-Ile and L-Val); (v) neutral amino acids with long linear side-chains (L-nLeu, L-nVal and L-Met); (vi) neutral amino acids with short side-chains; and (vii) amino acids with sulfhydryl groups (L-Cys and L-homoCys). PMID:10667990

  15. Photoacoustic spectroscopy study of neodymium complexes with alanine, valine, phenylalanine and tryptophan.

    PubMed

    Yang, Yuetao; Zhang, Shuyi

    2003-04-01

    Neodymium complexes with amino acids: Nd(Ala)(3)Cl(3).3H(2)O, Nd(Val)(3)Cl(3).3H(2)O, Nd(Phe)Cl(3).5H(2)O and Nd(Trp)(3)Cl(3).3H(2)O (Ala: L-alanine, Val: L-valine, Phe: L-phenylalanine, Trp: L-tryptophan) are synthesized and their photoacoustic (PA) spectra are reported. The nephelauxetic ratio beta, bonding parameter b(1/2) and Sinha parameter delta are calculated based on their PA spectra. The variation of these parameters and correlation of them with the nature of metal-ligand bonding are discussed. The PA intensity analysis of the f-f transitions of neodymium ion is carried out by calculating the intensity branching vector. The environmental effect on the f-f transitions of neodymium ion is also studied. The branching vectors of the f-f transitions of Nd(Ala)(3)Cl(3).3H(2)O and Nd(Val)(3)Cl(3).3H(2)O are similar, which indicates the perturbation of the two ligand fields is similar. The branching vectors of energy levels 4G(5/2)+(2)G(7/2) of Nd(Phe)Cl(3).5H(2)O and Nd(Trp)(3)Cl(3).3H(2)O increase remarkably compared with those of Nd(Ala)(3)Cl(3).3H(2)O and Nd(Val)(3)Cl(3).3H(2)O. As the degree of covalency increases, the oscillator strength of the hypersensitive transition exhibits a corresponding increase. The relaxation process of Nd(Ala)(3)Cl(3).3H(2)O is established through its PA and electron absorption spectroscopy (EAS). A method used to resolve the PA amplitude spectrum is suggested. With the phase spectrum, PA absorption bands of Nd(Trp)(3)Cl(3).3H(2)O are resolved well in the region of ligand absorption. PMID:12659889

  16. Leucine metabolism in cirrhotic patients with hepatic encephalopathy

    SciTech Connect

    McGhee, A.S.

    1985-01-01

    The purpose of this study was to determine whether increased oxidation of or protein synthesis requiring leucine occurs in cirrhotic patients. Five control subjects and four subjects with cirrhosis were equilibrated on a baseline diet (0.6 g protein per kg ideal body weight (IBW)) with sufficient nonprotein calories to preclude negative nitrogen balance. An additional four patients were equilibrated on the same type of diet with a higher protein level (0.75 g per kg IBW). Control subjects and the patients were then studied during continuous infusion of L-(/sup 15/N, 1-/sup 13/C) leucine in the fasted state and, in the fed state, with a Propac diet which had the same distribution of energy nutrients as the baseline diets. Plasma levels of L-(/sup 15/N, 1-/sup 13/C), L-(1-/sup 13/C) and L-(/sup 15/N) leucine were measured during isotopic steady state by gas chromatography-mass spectrometry and fractional excretion of /sup 13/CO/sup 2/ in breath samples were analyzed by isotopic ratio mass spectrometry. During the fasted and fed states leucine metabolism was measured to quantitate rates of nitrogen flux (Q/sub N/), carbon flux (Q/sub c/) and oxidation to carbon dioxide and water (C). From these measured values, proteins breakdown (B), protein synthesis (S), deamination (X/sup 0/) and reamination (X/sub N/) were calculated. The results showed that protein synthesis and leucine metabolism were identical in controls and patients when both were fed a diet with 0.6 g protein/kg IBW and maintenance level of nonprotein calories. The data also showed that leucine metabolism can be quantitatively and reproducibly measured in subjects with cirrhosis.

  17. ΔpH-Dependent Amino Acid Transport into Plasma Membrane Vesicles Isolated from Sugar Beet Leaves

    PubMed Central

    Li, Zhen-Chang; Bush, Daniel R.

    1990-01-01

    Amino acid transport into plasma membrane vesicles isolated from mature sugar beet (Beta vulgaris L. cv Great Western) leaves was investigated. The transport of alanine, leucine, glutamine, glutamate, isoleucine, and arginine was driven by a trans-membrane proton concentration difference. ΔpH-Dependent alanine, leucine, glutamine, and glutamate transport exhibited simple Michaelis-Menten kinetics, and double-reciprocal plots of the data were linear with apparent Km values of 272, 346, 258, and 1981 micromolar, respectively. These results are consistent with carrier mediated transport. ΔpH-Dependent isoleucine and arginine transport exhibited biphasic kinetics, suggesting these amino acids may be transported by at least two transport systems. Symport mediated alanine transport was electrogenic as demonstrated by the effect of membrane potential (ΔΨ) on ΔpH-dependent flux. In the absence of significant charge compensation, a low rate of alanine transport was observed. When ΔΨ was held at 0 millivolt with symmetric potassium concentrations and valinomycin, the rate of flux was stimulated fourfold. In the presence of a negative ΔΨ, alanine transport increased sixfold. These results are consistent with an electrogenic transport process which results in a net flux of positive charge into the vesicles. The effect of changing ΔΨ on the kinetics of alanine transport altered Vmax with no apparent change in Km. Amino acid transport was inhibited by the protein modifier diethyl pyrocarbonate, but was insensitive to N-ethylmaleimide, 4,4′-diisothiocyano-2,2′-stilbene disulfonic acid, p-chloromercuribenzenesulfonic acid, phenylglyoxal, and N,N′-dicyclohexylcarbodiimide. Four amino acid symport systems, two neutral, one acidic, and one basic, were resolved based on inter-amino acid competition experiments. One neutral system appears to be active for all neutral amino acids while the second exhibited a low affinity for isoleucine, threonine, valine, and proline

  18. The enthalpy of solution of DL-α-alanyl-DL-α-valine depending on the composition of water-alcohol binary solvents at 298.15 K

    NASA Astrophysics Data System (ADS)

    Smirnov, V. I.; Badelin, V. G.

    2008-12-01

    The integral enthalpies of solution of DL-α-alanyl-DL-α-valine in water-ethanol, water- n-propanol, and water-isopropanol mixtures at alcohol concentrations x 2 = 0-0.4 mole fractions were measured calorimetrically. The enthalpies of solution of the peptide Δsol H° and transfer from water to a mixed solvent Δtr H° were calculated. The effect of the structure and properties of the peptide and mixture composition on the enthalpy characteristics of the peptide are discussed. The enthalpy coefficients of pair interactions h xy of DL-α-alanyl-DL-α-valine with alcohol molecules were calculated. It was found that they were positive and increased in the series ethanol, n-propanol, isopropanol. An analysis of the results allows the general features of changes in the thermodynamic parameters of solution of peptides of the DL-α-alanine series with different amino acid residues in water-alcohol mixtures to be established.

  19. Surface-anchored poly(acryloyl-L(D)-valine) with enhanced chirality-selective effect on cellular uptake of gold nanoparticles.

    PubMed

    Deng, Jun; Wu, Sai; Yao, Mengyun; Gao, Changyou

    2016-01-01

    Chirality is one of the ubiquitous phenomena in biological systems. The left handed (L-) amino acids and right handed (D-) sugars are normally found in proteins, and in RNAs and DNAs, respectively. The effect of chiral surfaces at the nanoscale on cellular uptake has, however, not been explored. This study reveals for the first time the molecular chirality on gold nanoparticles (AuNPs) functions as a direct regulator for cellular uptake. Monolayers of 2-mercaptoacetyl-L(D)-valine (L(D)-MAV) and poly(acryloyl-L(D)-valine (L(D)-PAV) chiral molecules were formed on AuNPs surface, respectively. The internalized amount of PAV-AuNPs was several times larger than that of MAV-AuNPs by A549 and HepG2 cells, regardless of the chirality difference. However, the D-PAV-AuNPs were internalized with significantly larger amount than the L-PAV-AuNPs. This chirality-dependent uptake effect is likely attributed to the preferable interaction between the L-phospholipid-based cell membrane and the D-enantiomers. PMID:27531648

  20. Surface-anchored poly(acryloyl-L(D)-valine) with enhanced chirality-selective effect on cellular uptake of gold nanoparticles

    PubMed Central

    Deng, Jun; Wu, Sai; Yao, Mengyun; Gao, Changyou

    2016-01-01

    Chirality is one of the ubiquitous phenomena in biological systems. The left handed (L-) amino acids and right handed (D-) sugars are normally found in proteins, and in RNAs and DNAs, respectively. The effect of chiral surfaces at the nanoscale on cellular uptake has, however, not been explored. This study reveals for the first time the molecular chirality on gold nanoparticles (AuNPs) functions as a direct regulator for cellular uptake. Monolayers of 2-mercaptoacetyl-L(D)-valine (L(D)-MAV) and poly(acryloyl-L(D)-valine (L(D)-PAV) chiral molecules were formed on AuNPs surface, respectively. The internalized amount of PAV-AuNPs was several times larger than that of MAV-AuNPs by A549 and HepG2 cells, regardless of the chirality difference. However, the D-PAV-AuNPs were internalized with significantly larger amount than the L-PAV-AuNPs. This chirality-dependent uptake effect is likely attributed to the preferable interaction between the L-phospholipid-based cell membrane and the D-enantiomers. PMID:27531648

  1. The Radiolysis and Radioracemization of Amino Acids on Silica Surfaces

    NASA Astrophysics Data System (ADS)

    Bonner, William A.; Lemmon, Richard M.

    1981-12-01

    L-Leucine, deposited on both 1-quartz powder and on a commercial amorphous silica preparation (Syloid 63), has been subjected to irradiation in a60Co γ-ray source, and the ensuing radiolysis and radioracemization have been determined gas chromatographically. The radiolysis and radioracemization observed for leucine on 1-quartz were rather similar to those noted for a crystalline L-leucine control. L-Leucine on Syloid 63, however, was vastly more susceptible to radiolysis as compared to the L-leucine control, and radioracemization was also markedly enhanced—each increasing with larger radiation dosage. L-Isovaline showed a similar, but diminished, enhancement of radiolysis sensitivity when adsorbed on the Syloid surface, but underwent no radioracemization whatsoever. The divergent results of the control and quartz-leucine irradiationsversus the Syloid-leucine and Syloid-isovaline irradiations are interpreted qualitatively in terms of the surface area parameters of the two silica adsorbents and the amino acid adsorbates.

  2. 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.

  3. 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

  4. Positive selection in the leucine-rich repeat domain of Gro1 genes in Solanum species.

    PubMed

    Ruggieri, Valentino; Nunziata, Angelina; Barone, Amalia

    2014-12-01

    In pathogen resistant plants, solvent-exposed residues in the leucine-rich repeat (LRR) proteins are thought to mediate resistance by recognizing plant pathogen elicitors. In potato, the gene Gro1-4 confers resistance to Globodera rostochiensis. The investigation of variability in different copies of this gene represents a good model for the verification of positive selection mechanisms. Two datasets of Gro1 LRR sequences were constructed, one derived from the Gro1-4 gene, belonging to different cultivated and wild Solanum species, and the other belonging to paralogues of a resistant genotype. Analysis of nonsynonymous to synonymous substitution rates (K(a)/K(s)) highlighted 14 and six amino acids with K(a)/K(s) >1 in orthologue and paralogue datasets, respectively. Selection analysis revealed that the leucine-rich regions accumulate variability in a very specific way, and we found that some combinations of amino acids in these sites might be involved in pathogen recognition. The results confirm previous studies on positive selection in the LRR domain of R protein in Arabidopsis and other model plants and extend these to wild Solanum species. Moreover, positively selected sites in the Gro1 LRR domain show that coevolution mainly occurred in two regions on the internal surface of the three-dimensional horseshoe structure of the domain, albeit with different evolutionary forces between paralogues and orthologues. PMID:25572234

  5. MHJ_0461 is a multifunctional leucine aminopeptidase on the surface of Mycoplasma hyopneumoniae.

    PubMed

    Jarocki, Veronica M; Santos, Jerran; Tacchi, Jessica L; Raymond, Benjamin B A; Deutscher, Ania T; Jenkins, Cheryl; Padula, Matthew P; Djordjevic, Steven P

    2015-01-01

    Aminopeptidases are part of the arsenal of virulence factors produced by bacterial pathogens that inactivate host immune peptides. Mycoplasma hyopneumoniae is a genome-reduced pathogen of swine that lacks the genetic repertoire to synthesize amino acids and relies on the host for availability of amino acids for growth. M. hyopneumoniae recruits plasmin(ogen) onto its cell surface via the P97 and P102 adhesins and the glutamyl aminopeptidase MHJ_0125. Plasmin plays an important role in regulating the inflammatory response in the lungs of pigs infected with M. hyopneumoniae. We show that recombinant MHJ_0461 (rMHJ_0461) functions as a leucine aminopeptidase (LAP) with broad substrate specificity for leucine, alanine, phenylalanine, methionine and arginine and that MHJ_0461 resides on the surface of M. hyopneumoniae. rMHJ_0461 also binds heparin, plasminogen and foreign DNA. Plasminogen bound to rMHJ_0461 was readily converted to plasmin in the presence of tPA. Computational modelling identified putative DNA and heparin-binding motifs on solvent-exposed sites around a large pore on the LAP hexamer. We conclude that MHJ_0461 is a LAP that moonlights as a multifunctional adhesin on the cell surface of M. hyopneumoniae. PMID:25589579

  6. MHJ_0461 is a multifunctional leucine aminopeptidase on the surface of Mycoplasma hyopneumoniae

    PubMed Central

    Jarocki, Veronica M.; Santos, Jerran; Tacchi, Jessica L.; Raymond, Benjamin B. A.; Deutscher, Ania T.; Jenkins, Cheryl; Padula, Matthew P.; Djordjevic, Steven P.

    2015-01-01

    Aminopeptidases are part of the arsenal of virulence factors produced by bacterial pathogens that inactivate host immune peptides. Mycoplasma hyopneumoniae is a genome-reduced pathogen of swine that lacks the genetic repertoire to synthesize amino acids and relies on the host for availability of amino acids for growth. M. hyopneumoniae recruits plasmin(ogen) onto its cell surface via the P97 and P102 adhesins and the glutamyl aminopeptidase MHJ_0125. Plasmin plays an important role in regulating the inflammatory response in the lungs of pigs infected with M. hyopneumoniae. We show that recombinant MHJ_0461 (rMHJ_0461) functions as a leucine aminopeptidase (LAP) with broad substrate specificity for leucine, alanine, phenylalanine, methionine and arginine and that MHJ_0461 resides on the surface of M. hyopneumoniae. rMHJ_0461 also binds heparin, plasminogen and foreign DNA. Plasminogen bound to rMHJ_0461 was readily converted to plasmin in the presence of tPA. Computational modelling identified putative DNA and heparin-binding motifs on solvent-exposed sites around a large pore on the LAP hexamer. We conclude that MHJ_0461 is a LAP that moonlights as a multifunctional adhesin on the cell surface of M. hyopneumoniae. PMID:25589579

  7. Cytosolic re-localization and optimization of valine synthesis and catabolism enables inseased isobutanol production with the yeast Saccharomyces cerevisiae

    PubMed Central

    2012-01-01

    Background The branched chain alcohol isobutanol exhibits superior physicochemical properties as an alternative biofuel. The yeast Saccharomyces cerevisiae naturally produces low amounts of isobutanol as a by-product during fermentations, resulting from the catabolism of valine. As S. cerevisiae is widely used in industrial applications and can easily be modified by genetic engineering, this microorganism is a promising host for the fermentative production of higher amounts of isobutanol. Results Isobutanol production could be improved by re-locating the valine biosynthesis enzymes Ilv2, Ilv5 and Ilv3 from the mitochondrial matrix into the cytosol. To prevent the import of the three enzymes into yeast mitochondria, N-terminally shortened Ilv2, Ilv5 and Ilv3 versions were constructed lacking their mitochondrial targeting sequences. SDS-PAGE and immunofluorescence analyses confirmed expression and re-localization of the truncated enzymes. Growth tests or enzyme assays confirmed enzymatic activities. Isobutanol production was only increased in the absence of valine and the simultaneous blockage of the mitochondrial valine synthesis pathway. Isobutanol production could be even more enhanced after adapting the codon usage of the truncated valine biosynthesis genes to the codon usage of highly expressed glycolytic genes. Finally, a suitable ketoisovalerate decarboxylase, Aro10, and alcohol dehydrogenase, Adh2, were selected and overexpressed. The highest isobutanol titer was 0.63 g/L at a yield of nearly 15 mg per g glucose. Conclusion A cytosolic isobutanol production pathway was successfully established in yeast by re-localization and optimization of mitochondrial valine synthesis enzymes together with overexpression of Aro10 decarboxylase and Adh2 alcohol dehydrogenase. Driving forces were generated by blocking competition with the mitochondrial valine pathway and by omitting valine from the fermentation medium. Additional deletion of pyruvate decarboxylase genes

  8. Intracerebroventricular administration of α-ketoisocaproic acid decreases brain-derived neurotrophic factor and nerve growth factor levels in brain of young rats.

    PubMed

    Wisniewski, Miriam S W; Carvalho-Silva, Milena; Gomes, Lara M; Zapelini, Hugo G; Schuck, Patrícia F; Ferreira, Gustavo C; Scaini, Giselli; Streck, Emilio L

    2016-04-01

    Maple syrup urine disease (MSUD) is an inherited aminoacidopathy resulting from dysfunction of the branched-chain keto acid dehydrogenase complex, leading to accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine and valine as well as their corresponding transaminated branched-chain α-ketoacids. This disorder is clinically characterized by ketoacidosis, seizures, coma, psychomotor delay and mental retardation whose pathophysiology is not completely understood. Recent studies have shown that oxidative stress may be involved in neuropathology of MSUD. However, the effect of accumulating α-ketoacids in MSUD on neurotrophic factors has not been investigated. Thus, the objective of the present study was to evaluate the effects of acute intracerebroventricular administration of α-ketoisocaproic acid (KIC) on brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels in the brains of young male rats. Ours results showed that intracerebroventricular administration of KIC decreased BDNF levels in hippocampus, striatum and cerebral cortex, without induce a detectable change in pro-BDNF levels. Moreover, NGF levels in the hippocampus were reduced after intracerebroventricular administration of KIC. In conclusion, these data suggest that the effects of KIC on demyelination and memory processes may be mediated by reduced trophic support of BDNF and NGF. Moreover, lower levels of BDNF and NGF are consistent with the hypothesis that a deficit in this neurotrophic factor may contribute to the structural and functional alterations of brain underlying the psychopathology of MSUD, supporting the hypothesis of a neurodegenerative process in MSUD. PMID:26586008

  9. Pathways of Amino Acid Degradation in Nilaparvata lugens (Stål) with Special Reference to Lysine-Ketoglutarate Reductase/Saccharopine Dehydrogenase (LKR/SDH)

    PubMed Central

    Wan, Pin-Jun; Yuan, San-Yue; Tang, Yao-Hua; Li, Kai-Long; Yang, Lu; Fu, Qiang; Li, Guo-Qing

    2015-01-01

    Nilaparvata lugens harbors yeast-like symbionts (YLSs). In present paper, a genome-wide analysis found 115 genes from Ni. lugens and 90 genes from YLSs that were involved in the metabolic degradation of 20 proteinogenic amino acids. These 205 genes encoded for 77 enzymes. Accordingly, the degradation pathways for the 20 amino acids were manually constructed. It is postulated that Ni. lugens can independently degrade fourteen amino acids (threonine, alanine, glycine, serine, aspartate, asparagine, phenylalanine, tyrosine, glutamate, glutamine, proline, histidine, leucine and lysine). Ni. lugens and YLSs enzymes may work collaboratively to break down tryptophan, cysteine, arginine, isoleucine, methionine and valine. We cloned a lysine-ketoglutarate reductase/saccharopine dehydrogenase gene (Nllkr/sdh) that encoded a bifunctional enzyme catalyzing the first two steps of lysine catabolism. Nllkr/sdh is widely expressed in the first through fifth instar nymphs and adults, and is highly expressed in the fat body, ovary and gut in adults. Ingestion of dsNllkr/sdh by nymphs successfully knocked down the target gene, and caused nymphal/adult mortality, shortened nymphal development stage and reduced adult fresh weight. Moreover, Nllkr/sdh knockdown resulted in three defects: wings were shortened and thickened; cuticles were stretched and thinned; and old nymphal cuticles remained on the tips of legs and abdomen and were not completely shed. These data indicate that impaired lysine degradation negatively affects the survival and development of Ni. lugens. PMID:26000452

  10. Chronic enteral leucine supplementation of a low protein diet increases skeletal muscle protein synthesis in neonatal pigs by stimulating mTOR-dependent translation initiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leucine appears to be the key amino acid that positively regulates mTOR signalling. We hypothesized that prolonged feeding (24 hours) of a Leu supplemented low protein (LP) diet in neonatal pigs will increase protein synthesis in skeletal muscle to a rate similar to that of a high protein diet (HP)....

  11. Amino acid replacements can selectively affect the interaction energy of autonomous folding units in the alpha subunit of tryptophan synthase.

    PubMed

    Chen, X; Rambo, R; Matthews, C R

    1992-03-01

    Amino acid replacements were made at the interface between two autonomous folding units in the alpha subunit of tryptophan synthase from Salmonella typhimurium to test their mutual interaction energy. The results of equilibrium studies of the urea-induced unfolding reaction of the wild-type and mutant proteins in which phenylalanine 22 is replaced by leucine, isoleucine, and valine can be understood in terms of a selective decrease in the interaction energy between the two folding units; the intrinsic stability of each folding unit is not significantly altered. Kinetic studies of the rate-limiting step in unfolding show that the interaction energy appears in the transition state preceding the native conformation. Comparisons of the individual effects of these nonpolar side chains show that both hydrophobic and steric effects play important roles in the interaction energy between the folding units. The implication of these results is that the high cooperativity observed in the folding of many globular proteins may be reduced by appropriate amino acid replacements. PMID:1540577

  12. A Whole-Cell Surface Plasmon Resonance Sensor Based on a Leucine Auxotroph of Escherichia coli Displaying a Gold-Binding Protein: Usefulness for Diagnosis of Maple Syrup Urine Disease.

    PubMed

    Woo, Min-Ah; Park, Jung Hun; Cho, Daeyeon; Sim, Sang Jun; Kim, Moon Il; Park, Hyun Gyu

    2016-03-01

    We developed a whole-cell surface plasmon resonance (SPR) sensor based on a leucine auxotroph of Escherichia coli displaying a gold-binding protein (GBP) in response to cell growth and applied this sensor to the diagnosis of maple syrup urine disease, which is represented by the elevated leucine level in blood. The leucine auxotroph was genetically engineered to grow displaying GBP in a proportion to the concentration of target amino acid leucine. The GBP expressed on the surface of the auxotrophs directly bound to the golden surface of an SPR chip without the need for any additional treatment or reagents, which consequently produced SPR signals used to determine leucine levels in a test sample. Gold nanoparticles (GNPs) were further applied to the SPR system, which significantly enhanced the signal intensity up to 10-fold by specifically binding to GBP expressed on the cell surface. Finally, the diagnostic utility of our system was demonstrated by its employment in reliably determining different statuses of maple syrup urine disease based on a known cutoff level of leucine. This new approach based on an amino acid-auxotrophic E. coli strain expressing a GBP that binds to an SPR sensor holds great promise for detection of other metabolic diseases of newborn babies including homocystinuria and phenylketonuria, which are also associated with abnormal levels of amino acids. PMID:26828904

  13. Growth of the salt-tolerant yeast Zygosaccharomyces rouxii in microtiter plates: effects of NaCl, pH and temperature on growth and fusel alcohol production from branched-chain amino acids.

    PubMed

    Jansen, Michael; Veurink, Janine H; Euverink, Gert-Jan W; Dijkhuizen, Lubbert

    2003-05-01

    Zygosaccharomyces rouxii, a salt-tolerant yeast isolated from the soy sauce process, produces fusel alcohols (isoamyl alcohol, active amyl alcohol and isobutyl alcohol) from branched-chain amino acids (leucine, isoleucine and valine, respectively) via the Ehrlich pathway. Using a high-throughput screening approach in microtiter plates, we have studied the effects of pH, temperature and salt concentration on growth of Z. rouxii and formation of fusel alcohols from branched-chain amino acids. Application of minor variations in pH (range 3-7) and NaCl concentrations (range 0-20%) per microtiter plate well allowed a rapid and detailed evaluation of fermentation conditions for optimal growth and metabolite production. Conditions yielding the highest cell densities were not optimal for fusel alcohol production. Maximal fusel alcohol production occurred at low pH (3.0-4.0) and low NaCl concentrations (0-4%) at 25 degrees C. At pH 4.0-6.0 and 0-18% NaCl, considerable amounts of alpha-keto acids, the deaminated products from the branched-chain amino acids, accumulated extracellularly. The highest cell densities were obtained in plates incubated at 30 degrees C. The results obtained under various incubation conditions with (deep-well) microtiter plates were validated in Erlenmeyer shake-flask cultures. PMID:12689638

  14. An Examination of the Carbon Isotope Effects Associated with Amino Acid Biosynthesis

    NASA Astrophysics Data System (ADS)

    Scott, James H.; O'Brien, Diane M.; Emerson, David; Sun, Henry; McDonald, Gene D.; Salgado, Antonio; Fogel, Marilyn L.

    2006-12-01

    Stable carbon isotope ratios (δ13C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glutamine), lysine, serine, glycine, and threonine from metabolically diverse microorganisms. The microorganisms examined included fermenting bacteria, organotrophic, chemolithotrophic, phototrophic, methylotrophic, methanogenic, acetogenic, acetotrophic, and naturally occurring cryptoendolithic communities from the Dry Valleys of Antarctica. Here we demonstrated that reactions involved in amino acid biosynthesis can be used to distinguish amino acids formed by life from those formed by nonbiological processes. The unique patterns of δ13C imprinted by life on amino acids produced a biological bias. We also showed that, by applying discriminant function analysis to the δ13C value of a pool of amino acids formed by biological activity, it was possible to identify key aspects of intermediary carbon metabolism in the microbial world. In fact, microorganisms examined in this study could be placed within one of three metabolic groups: (1) heterotrophs that grow by oxidizing compounds containing three or more carbon-to-carbon bonds (fermenters and organotrophs), (2) autotrophs that grow by taking up carbon dioxide (chemolitotrophs and phototrophs), and (3) acetoclastic microbes that grow by assimilation of formaldehyde or acetate (methylotrophs, methanogens, acetogens, and acetotrophs). Furthermore, we demonstrated that cryptoendolithic communities from Antarctica grouped most closely with the autotrophs, which indicates that the dominant metabolic pathways in these communities are likely those utilized for CO2 fixation. We propose that this technique can be used to determine the dominant metabolic types in a community and reveal the overall flow of carbon in a complex ecosystem.

  15. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Leucine aminopeptidase test system. 862.1460 Section 862.1460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry...

  16. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Leucine aminopeptidase test system. 862.1460 Section 862.1460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry...

  17. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Leucine aminopeptidase test system. 862.1460 Section 862.1460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry...

  18. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Leucine aminopeptidase test system. 862.1460 Section 862.1460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry...

  19. Substitution of valine for histidine 265 in carbon monoxide dehydrogenase from Rhodospirillum rubrum affects activity and spectroscopic states.

    PubMed

    Spangler, N J; Meyers, M R; Gierke, K L; Kerby, R L; Roberts, G P; Ludden, P W

    1998-02-13

    In carbon monoxide dehydrogenase (CODH) from Rhodospirillum rubrum, histidine 265 was replaced with valine by site-directed mutagenesis of the cooS gene. The altered form of CODH (H265V) had a low nickel content and a dramatically reduced level of catalytic activity. Although treatment with NiCl2 and CoCl2 increased the activity of H265V CODH by severalfold, activity levels remained more than 1000-fold lower than that of wild-type CODH. Histidine 265 was not essential for the formation and stability of the Fe4S4 clusters. The Km and KD for CO as well as the KD for cyanide were relatively unchanged as a result of the amino acid substitution in CODH. The time-dependent reduction of the [Fe4S4]2+ clusters by CO occurred on a time scale of hours, suggesting that, as a consequence of the mutation, a rate-limiting step had been introduced prior to the transfer of electrons from CO to the cubanes in centers B and C. EPR spectra of H265V CODH lacked the gav = 1.86 and gav = 1.87 signals characteristic of reduced forms of the active site (center C) of wild-type CODH. This indicates that the electronic properties of center C have been modified possibly by the disruption or alteration of the ligand-mediated interaction between the nickel site and Fe4S4 chromophore. PMID:9461598

  20. Plasma reciprocal pool specific activity predicts that of intracellular free leucine for protein synthesis

    SciTech Connect

    Horber, F.F.; Horber-Feyder, C.M.; Krayer, S.; Schwenk, W.F.; Haymond, M.W. )

    1989-09-01

    We previously proposed that, during the infusion of either labeled leucine or its alpha-ketoacid, alpha-ketoisocaproate (KIC), the plasma specific activity (SA) of the transaminated product of the infused tracer (reciprocal pool SA) may better reflect the intracellular leucine SA than the plasma SA of either infused tracer (primary pool SA). To test this hypothesis, 14 dogs were simultaneously infused intravenously with (3H)leucine and (14C)KIC, and blood and tissue compartments were sampled. The ratios of (3H)-leucine to (14C)leucine (3H)/(14C)leucine in mixed tissue proteins and in the intracellular space of striated muscle were the same as the ratio of the isotope infusion rates and similar, although slightly lower (P less than 0.01), than (3H)KIC/(14C)leucine SA (ratio of reciprocal pool SA) in plasma. Plasma (3H)KIC/(14C)leucine SA were essentially identical to the (3H)/(14C) of leucine in (1) mixed liver proteins, (2) intrahepatic free leucine, and (3) fibrin. The (3H)/(14C)leucine in mixed renal proteins and in the intracellular space of kidney and erythrocytes were similar to those of the venous plasma (3H)/(14C)leucine SA. The plasma (3H)KIC and (14C)leucine SA (the reciprocal pool SA) were similar to the SA of (3H)- and (14C)leucine in the intracellular space of all organs investigated with the exception of kidney. Therefore, in postabsorptive dogs, the plasma SA of the transaminated product of the infused labeled KIC or leucine is an excellent predictor of the intracellular leucine SA in all tissues investigated with the exception of kidney.

  1. Protein-leucine ingestion activates a regenerative inflammo-myogenic transcriptome in skeletal muscle following intense endurance exercise.

    PubMed

    Rowlands, David S; Nelson, Andre R; Raymond, Frederic; Metairon, Sylviane; Mansourian, Robert; Clarke, Jim; Stellingwerff, Trent; Phillips, Stuart M

    2016-01-01

    Protein-leucine supplement ingestion following strenuous endurance exercise accentuates skeletal-muscle protein synthesis and adaptive molecular responses, but the underlying transcriptome is uncharacterized. In a randomized single-blind triple-crossover design, 12 trained men completed 100 min of high-intensity cycling then ingested 70/15/180/30 g protein-leucine-carbohydrate-fat (15LEU), 23/5/180/30 g (5LEU), or 0/0/274/30 g (CON) beverages during the first 90 min of a 240 min recovery period. Vastus lateralis muscle samples (30 and 240 min postexercise) underwent transcriptome analysis by microarray followed by bioinformatic analysis. Gene expression was regulated by protein-leucine in a dose-dependent manner affecting the inflammatory response and muscle growth and development. At 30 min, 15LEU and 5LEU vs. CON activated transcriptome networks with gene-set functions involving cell-cycle arrest (Z-score 2.0-2.7, P < 0.01), leukocyte maturation (1.7, P = 0.007), cell viability (2.4, P = 0.005), promyogenic networks encompassing myocyte differentiation and myogenin (MYOD1, MYOG), and a proteinaceous extracellular matrix, adhesion, and development program correlated with plasma lysine, arginine, tyrosine, taurine, glutamic acid, and asparagine concentrations. High protein-leucine dose (15LEU-5LEU) activated an IL-1I-centered proinflammatory network and leukocyte migration, differentiation, and survival functions (2.0-2.6, <0.001). By 240 min, the protein-leucine transcriptome was anti-inflammatory and promyogenic (IL-6, NF- β, SMAD, STAT3 network inhibition), with overrepresented functions including decreased leukocyte migration and connective tissue development (-1.8-2.4, P < 0.01), increased apoptosis of myeloid and muscle cells (2.2-3.0, P < 0.002), and cell metabolism (2.0-2.4, P < 0.01). The analysis suggests protein-leucine ingestion modulates inflammatory-myogenic regenerative processes during skeletal muscle recovery from endurance exercise. Further

  2. Alteration of organic matter during infaunal polychaete gut passage and links to sediment organic geochemistry. Part I: Amino acids

    NASA Astrophysics Data System (ADS)

    Woulds, Clare; Middelburg, Jack J.; Cowie, Greg L.

    2012-01-01

    Of the factors which control the quantity and composition of organic matter (OM) buried in marine sediments, the links between infaunal ingestion and gut passage and sediment geochemistry have received relatively little attention. This study aimed to use feeding experiments and novel isotope tracing techniques to quantify amino acid net accumulation and loss during polychaete gut passage, and to link this to patterns of selective preservation and decay in sediments. Microcosms containing either Arenicolamarina or Hediste (formerly Nereis) diversicolor were constructed from defaunated sediment and filtered estuarine water, and maintained under natural temperature and light conditions. They were fed with 13C-labelled diatoms daily for 8 days, and animals were transferred into fresh, un-labelled sediment after ∼20 days. Samples of fauna, microcosm sediment and faecal matter were collected after 8, ∼20 and ∼40 days, and analysed for their bulk isotopic signatures and 13C-labelled amino acid compositions. Bulk isotopic data showed that, consistent with their feeding modes, Hediste assimilated added 13C more quickly, and attained a higher labelling level than Arenicola. Both species retained the added 13C in their biomass even after removal from the food. A principal component analysis of 13C-labelled amino acid mole percentages showed clear differences in composition between the algae, faunal tissues, and sediment plus faecal matter. Further, the two species of polychaete showed different compositions in their tissues. The amino acids phenylalanine, valine, leucine, iso-leucine, threonine and proline showed net accumulation in polychaete tissues. Serine, methionine, lysine, aspartic and glutamic acids and tyrosine were rapidly lost through metabolism, consistent with their presence in easily digestible cell components (as opposed to cell walls which offer physical protection). All sample types (polychaete tissues, sediments and faecal matter) were enriched in

  3. Association of amino acids embedded in helium droplets detected by mass spectrometry

    NASA Astrophysics Data System (ADS)

    Lalanne, Matthieu R.; Achazi, Georg; Reichwald, Sebastian; Lindinger, Albrecht

    2015-12-01

    Amino acids were embedded in helium droplets. The electron impact ionization allows for detecting positively charged glycine, valine, histidine, tryptophan and their principal fragments. Monomers and polymers with up to four amino acids are reported. Heterodimers of tryptophan and valine or histidine are observed as well as heterodimers of included fragments. The ability of these associations of molecules to form complexes with water is examined.

  4. Vibrational absorption and vibrational circular dichroism spectra of leucine in water under different pH conditions: hydrogen-bonding interactions with water.

    PubMed

    Poopari, Mohammad Reza; Zhu, Peiyan; Dezhahang, Zahra; Xu, Yunjie

    2012-11-21

    Vibrational absorption (VA) and vibrational circular dichroism (VCD) spectroscopy have been used to study leucine, a flexible branched-chain amino acid, in aqueous solution. The VA spectra in the range of 1800-1250 cm(-1) of leucine in D(2)O under three representative pHs from strongly acidic (pH = 1), near neutral (pH = 6), to strongly basic (pH = 13), have been measured. The related VCD spectrum has been obtained under near neutral condition. Searches have been carried out to identify the most stable conformers of the Zwitterionic, protonated, and deprotonated forms of leucine in water. The geometry optimization, harmonic frequency calculations, and VA and VCD intensities have been computed at the B3LYP/6-311++G(d,p) level with the implicit polarizable continuum solvation model. While the observed VA spectra under three pHs can be well interpreted with the inclusion of the implicit solvation model, both implicit and explicit solvation models have been found to be crucial for the adequate interpretation of the complex VCD features observed. Molecular dynamics simulations and radial distribution functions have been used to aid the modeling of the leucine-(water)(N) clusters. It has been recognized that the insertion of a water molecule between the COO(-) and NH(3) (+) functional groups in the explicit solvated clusters is critical to reproduce the VCD signatures observed. Furthermore, the inclusion of the implicit bulk water environment has been found to be essential to lock water molecules, which are directly hydrogen bonded to leucine, into the positions expected in solution. The application of the explicit and implicit solvation models simultaneously allows new insights into the hydrogen bonding network surrounding leucine in aqueous solution and the role of the surrounding bulk water in stabilizing such hydrogen-bonding network. PMID:23181307

  5. Vibrational absorption and vibrational circular dichroism spectra of leucine in water under different pH conditions: Hydrogen-bonding interactions with water

    NASA Astrophysics Data System (ADS)

    Poopari, Mohammad Reza; Zhu, Peiyan; Dezhahang, Zahra; Xu, Yunjie

    2012-11-01

    Vibrational absorption (VA) and vibrational circular dichroism (VCD) spectroscopy have been used to study leucine, a flexible branched-chain amino acid, in aqueous solution. The VA spectra in the range of 1800-1250 cm-1 of leucine in D2O under three representative pHs from strongly acidic (pH = 1), near neutral (pH = 6), to strongly basic (pH = 13), have been measured. The related VCD spectrum has been obtained under near neutral condition. Searches have been carried out to identify the most stable conformers of the Zwitterionic, protonated, and deprotonated forms of leucine in water. The geometry optimization, harmonic frequency calculations, and VA and VCD intensities have been computed at the B3LYP/6-311++G(d,p) level with the implicit polarizable continuum solvation model. While the observed VA spectra under three pHs can be well interpreted with the inclusion of the implicit solvation model, both implicit and explicit solvation models have been found to be crucial for the adequate interpretation of the complex VCD features observed. Molecular dynamics simulations and radial distribution functions have been used to aid the modeling of the leucine-(water)N clusters. It has been recognized that the insertion of a water molecule between the COO- and NH3+ functional groups in the explicit solvated clusters is critical to reproduce the VCD signatures observed. Furthermore, the inclusion of the implicit bulk water environment has been found to be essential to lock water molecules, which are directly hydrogen bonded to leucine, into the positions expected in solution. The application of the explicit and implicit solvation models simultaneously allows new insights into the hydrogen bonding network surrounding leucine in aqueous solution and the role of the surrounding bulk water in stabilizing such hydrogen-bonding network.

  6. Plasma amino acid and metabolite signatures tracking diabetes progression in the UCD-T2DM rat model.

    PubMed

    Piccolo, Brian D; Graham, James L; Stanhope, Kimber L; Fiehn, Oliver; Havel, Peter J; Adams, Sean H

    2016-06-01

    Elevations of plasma concentrations of branched-chain amino acids (BCAAs) are observed in human insulin resistance and type 2 diabetes mellitus (T2DM); however, there has been some controversy with respect to the passive or causative nature of the BCAA phenotype. Using untargeted metabolomics, plasma BCAA and other metabolites were assessed in lean control Sprague-Dawley rats (LC) and temporally during diabetes development in the UCD-T2DM rat model, i.e., prediabetic (PD) and 2 wk (D2W), 3 mo (D3M), and 6 mo (D6M) post-onset of diabetes. Plasma leucine, isoleucine, and valine concentrations were elevated only in D6M rats compared with D2W rats (by 28, 29, and 30%, respectively). This was in contrast to decreased plasma concentrations of several other amino acids in D3M and/or D6M relative to LC rats (Ala, Arg, Glu, Gln, Met, Ser, Thr, and Trp). BCAAs were positively correlated with fasting glucose and negatively correlated with plasma insulin, total body weight, total adipose tissue weight, and gastrocnemius muscle weight in the D3M and D6M groups. Multivariate analysis revealed that D3M and D6M UCD-T2DM rats had lower concentrations of amino acids, amino acid derivatives, 1,5-anhydroglucitol, and conduritol-β-opoxide and higher concentrations of uronic acids, pantothenic acids, aconitate, benzoic acid, lactate, and monopalmitin-2-glyceride relative to PD and D2W UCD-T2DM rats. The UCD-T2DM rat does not display elevated plasma BCAA concentrations until 6 mo post-onset of diabetes. With the acknowledgement that this is a rodent model of T2DM, the results indicate that elevated plasma BCAA concentrations are not necessary or sufficient to elicit an insulin resistance or T2DM onset. PMID:27094034

  7. Effect of dietary essential amino acid limitations upon the susceptibility to Salmonella typhimurium and the effect upon humoral and cellular immune responses in mice.

    PubMed

    Petro, T M; Bhattacharjee, J K

    1981-04-01

    We investigated the effects of dietary essential amino acid limitations on the susceptibility of mice to Salmonella typhimurium infections and on humoral and cellular immune (cell-mediated immune) responses of mice. Mice fed synthetic diets limited (significantly less than optimum concentration) in a single essential amino acid (leucine, isoleucine, valine, or lysine) for 3 weeks after they were weaned exhibited significantly enhanced susceptibility to S. typhimurium infection, as evidenced by the higher levels of mortality and spread of the bacterial cells in their livers and spleens compared with mice fed the control diet. Compared with mice fed the control diet, mice fed the diet limited in leucine had a lower ability to clear S. typhimurium cells from the peritoneal cavity 5 min after intraperitoneal injection, whereas mice fed the diet limited in lysine had a greater ability. The in vivo phagocytosis and in vitro bactericidal kinetics against S. typhimurium cells by peritoneal macrophages were not significantly different in the control group and the groups of mice fed experimental diets. Certain experimental groups exhibited significantly lower resistance and antibody response against S. typhimurium SL3770 on day 5 after immunization with heat-killed S. typhimurium SL3770. On day 8 after immunization, the levels of serum antibody against S. typhimurium in the mice fed the experimental diets were comparable to the levels in mice fed the control diet. However, the levels of serum transferrin and complement C3 were significantly lower in mice fed certain experimental diets. The cellular immune capacities of mice fed any of the experimental diets were not impaired compared with the capacities of mice fed the control diet, as measured by spleen cell responsiveness to phytohemagglutinin and the ability to clear infecting Listeria monocytogenes cells from livers and spleens. PMID:7012029

  8. Effect of leucine-to-methionine substitutions on the diffraction quality of histone chaperone SET/TAF-Ibeta/INHAT crystals.

    PubMed

    Senda, Miki; Muto, Shinsuke; Horikoshi, Masami; Senda, Toshiya

    2008-10-01

    One of the most frequent problems in crystallization is poor quality of the crystals. In order to overcome this obstacle several methods have been utilized, including amino-acid substitutions of the target protein. Here, an example is presented of crystal-quality improvement by leucine-to-methionine substitutions. A variant protein with three amino-acid substitutions enabled improvement of the crystal quality of the histone chaperone SET/TAF-Ibeta/INHAT when combined with optimization of the cryoconditions. This procedure improved the resolution of the SET/TAF-Ibeta/INHAT crystals from around 5.5 to 2.3 A without changing the crystallization conditions. PMID:18931446

  9. Amino acid mixture acutely improves the glucose tolerance of healthy overweight adults.

    PubMed

    Wang, Bei; Kammer, Lynne M; Ding, Zhenping; Lassiter, David G; Hwang, Jungyun; Nelson, Jeffrey L; Ivy, John L

    2012-01-01

    Certain amino acids have been reported to influence carbohydrate metabolism and blood glucose clearance, as well as improve the glucose tolerance in animal models. We hypothesized that an amino acid mixture consisting of isoleucine and 4 additional amino acids would improve the glucose response of healthy overweight men and women to an oral glucose tolerance test (OGTT). Twenty-two overweight healthy subjects completed 2 OGTTs after consuming 2 different test beverages. The amino acid mixture beverage (CHO/AA) consisted of 0.088 g cystine 2HCl, 0.043 g methionine, 0.086 g valine, 12.094 g isoleucine, 0.084 g leucine, and 100 g dextrose. The control beverage (CHO) consisted of 100 g dextrose only. Venous blood samples were drawn 10 minutes before the start of ingesting the drinks and 15, 30, 60, 120, and 180 minutes after the completion of the drinks. During the OGTT, the plasma glucose response for the CHO/AA treatment was significantly lower than that of the CHO treatment (P < .01), as was the plasma glucose area under the curve (CHO/AA 806 ± 31 mmol/L·3 hours vs CHO 942 ± 40 mmol/L·3 hours). Differences in plasma glucose between treatments occurred at 30, 60, 120, and 180 minutes after supplement ingestion. Plasma glucagon during the CHO/AA treatment was significantly higher than during the CHO treatment. However, there were no significant differences in plasma insulin or C-peptide responses between treatments. These results suggest that the amino acid mixture lowers the glucose response to an OGTT in healthy overweight subjects in an insulin-independent manner. PMID:22260861

  10. Identification, purification, and characterization of a novel amino acid racemase, isoleucine 2-epimerase, from Lactobacillus species.

    PubMed

    Mutaguchi, Yuta; Ohmori, Taketo; Wakamatsu, Taisuke; Doi, Katsumi; Ohshima, Toshihisa

    2013-11-01

    Accumulation of d-leucine, d-allo-isoleucine, and d-valine was observed in the growth medium of a lactic acid bacterium, Lactobacillus otakiensis JCM 15040, and the racemase responsible was purified from the cells and identified. The N-terminal amino acid sequence of the purified enzyme was GKLDKASKLI, which is consistent with that of a putative γ-aminobutyrate aminotransferase from Lactobacillus buchneri. The putative γ-aminobutyrate aminotransferase gene from L. buchneri JCM 1115 was expressed in recombinant Escherichia coli and then purified to homogeneity. The enzyme catalyzed the racemization of a broad spectrum of nonpolar amino acids. In particular, it catalyzed at high rates the epimerization of l-isoleucine to d-allo-isoleucine and d-allo-isoleucine to l-isoleucine. In contrast, the enzyme showed no γ-aminobutyrate aminotransferase activity. The relative molecular masses of the subunit and native enzyme were estimated to be about 49 kDa and 200 kDa, respectively, indicating that the enzyme was composed of four subunits of equal molecular masses. The Km and Vmax values of the enzyme for l-isoleucine were 5.00 mM and 153 μmol·min(-1)·mg(-1), respectively, and those for d-allo-isoleucine were 13.2 mM and 286 μmol·min(-1)·mg(-1), respectively. Hydroxylamine and other inhibitors of pyridoxal 5'-phosphate-dependent enzymes completely blocked the enzyme activity, indicating the enzyme requires pyridoxal 5'-phosphate as a coenzyme. This is the first evidence of an amino acid racemase that specifically catalyzes racemization of nonpolar amino acids at the C-2 position. PMID:24039265

  11. Identification, Purification, and Characterization of a Novel Amino Acid Racemase, Isoleucine 2-Epimerase, from Lactobacillus Species

    PubMed Central

    Mutaguchi, Yuta; Ohmori, Taketo; Wakamatsu, Taisuke; Doi, Katsumi

    2013-01-01

    Accumulation of d-leucine, d-allo-isoleucine, and d-valine was observed in the growth medium of a lactic acid bacterium, Lactobacillus otakiensis JCM 15040, and the racemase responsible was purified from the cells and identified. The N-terminal amino acid sequence of the purified enzyme was GKLDKASKLI, which is consistent with that of a putative γ-aminobutyrate aminotransferase from Lactobacillus buchneri. The putative γ-aminobutyrate aminotransferase gene from L. buchneri JCM 1115 was expressed in recombinant Escherichia coli and then purified to homogeneity. The enzyme catalyzed the racemization of a broad spectrum of nonpolar amino acids. In particular, it catalyzed at high rates the epimerization of l-isoleucine to d-allo-isoleucine and d-allo-isoleucine to l-isoleucine. In contrast, the enzyme showed no γ-aminobutyrate aminotransferase activity. The relative molecular masses of the subunit and native enzyme were estimated to be about 49 kDa and 200 kDa, respectively, indicating that the enzyme was composed of four subunits of equal molecular masses. The Km and Vmax values of the enzyme for l-isoleucine were 5.00 mM and 153 μmol·min−1·mg−1, respectively, and those for d-allo-isoleucine were 13.2 mM and 286 μmol·min−1·mg−1, respectively. Hydroxylamine and other inhibitors of pyridoxal 5′-phosphate-dependent enzymes completely blocked the enzyme activity, indicating the enzyme requires pyridoxal 5′-phosphate as a coenzyme. This is the first evidence of an amino acid racemase that specifically catalyzes racemization of nonpolar amino acids at the C-2 position. PMID:24039265

  12. Amino acid and vascular endothelial growth factor levels in subretinal fluid in rhegmatogenous retinal detachment

    PubMed Central

    Buyukuysal, Rifat Levent; Gelisken, Oner; Buyukuysal, Cagatay; Can, Basak

    2014-01-01

    Purpose To study the concentrations of amino acids and vascular endothelial growth factor (VEGF) in subretinal fluid (SRF) of cases with rhegmatogenous retinal detachment (RRD). The relevance of the results with postoperative anatomic and functional success in RRD was investigated. Methods Fifty-three patients were included in this prospective study. The study group consisted of 46 patients who had scleral buckling surgery with the diagnosis of RRD, and SRF was obtained during the surgery. The control specimens consisted of vitreous samples of seven patients who were diagnosed with pars plana vitrectomy without RRD. Study cases were divided into three groups, corresponding to the duration of retinal detachment. Clinical characteristics, including best corrected visual acuity (BCVA) and anatomic status at month 6, were recorded. Concentrations of 15 selected amino acids were quantified by using high performance liquid chromatography, and VEGF levels were measured with enzyme immunoassay. Results When compared with the control group, SRF concentrations of aspartate, citrulline, glutamate, and glycine increased significantly in the study group (p<0.05). Statistical analysis showed that concentrations of alanine, isoleucine, leucine, methionine, phenylalanine, threonine, tyrosine, and valine decreased (p<0.05). SRF levels of glutamine, taurine, and serine had no significant change. SRF VEGF levels were significantly higher than the vitreous samples of the controls (p<0.001). Time-dependent changes and interactions between VEGF and amino acids were observed. There was no correlation between the concentrations of amino acids or VEGF with the parameters of BCVA and anatomical success. Conclusions Significant changes occur in concentrations of amino acids and VEGF in SRF of cases with RRD. Our results suggest that several mechanisms contribute to the pathophysiology. PMID:25352742

  13. Paramagnetic molecular centers in the gamma-irradiated novel compound of aluminum and leucine, Al 6O 4(OH) 10(leucine) 2·5H 2O

    NASA Astrophysics Data System (ADS)

    Nothig-Laslo, Vesna; Himdan, Takialdin A.; Bilinski, Halka

    A new microcrystalline compound Al 6O 4(OH) 10(leucine) 2·5H 2O of possible biological and biochemical interest has been prepared and characterized by chemical analysis, i.r. spectrum, X-ray diffraction and thermogravimetric analysis. It was exposed to γ-irradiation at 77 K and at room temperature. Paramagnetic species formed were studied by ESR spectroscopy. The leucine radical ? has been identified which seems to be stabilized in the aluminium leucine compound by crystalline water. Coordinated leucine molecule in aluminium hydroxide acts as a trap for γ-irradiation energy.

  14. Structure and Mechanism of Isopropylmalate Dehydrogenase from Arabidopsis thaliana: INSIGHTS ON LEUCINE AND ALIPHATIC GLUCOSINOLATE BIOSYNTHESIS.

    PubMed

    Lee, Soon Goo; Nwumeh, Ronald; Jez, Joseph M

    2016-06-24

    Isopropylmalate dehydrogenase (IPMDH) and 3-(2'-methylthio)ethylmalate dehydrogenase catalyze the oxidative decarboxylation of different β-hydroxyacids in the leucine- and methionine-derived glucosinolate biosynthesis pathways, respectively, in plants. Evolution of the glucosinolate biosynthetic enzyme from IPMDH results from a single amino acid substitution that alters substrate specificity. Here, we present the x-ray crystal structures of Arabidopsis thaliana IPMDH2 (AtIPMDH2) in complex with either isopropylmalate and Mg(2+) or NAD(+) These structures reveal conformational changes that occur upon ligand binding and provide insight on the active site of the enzyme. The x-ray structures and kinetic analysis of site-directed mutants are consistent with a chemical mechanism in which Lys-232 activates a water molecule for catalysis. Structural analysis of the AtIPMDH2 K232M mutant and isothermal titration calorimetry supports a key role of Lys-232 in the reaction mechanism. This study suggests that IPMDH-like enzymes in both leucine and glucosinolate biosynthesis pathways use a common mechanism and that members of the β-hydroxyacid reductive decarboxylase family employ different active site features for similar reactions. PMID:27137927

  15. Complex coacervates obtained from peptide leucine and gum arabic: formation and characterization.

    PubMed

    Gulão, Eliana da S; de Souza, Clitor J F; Andrade, Cristina T; Garcia-Rojas, Edwin E

    2016-03-01

    In this study, interactions between polypeptide-leucine (0.2% w/w) and gum arabic (0.03, 0.06, 0.09, 0.12, and 0.15% w/w) were examined at concentrations of NaCl (0, 0.01, 0.25, 0.3, 0.5mol/l) and at different pH values (from 1.0 to 12.0). Formation of insoluble complex coacervates was highest at pH 4.0. At pH 2.0, which is the pKa of the gum Arabic, the dissociation of precipitate occurred. The pHØ2 positively shifted with the addition of higher concentrations of salt. Samples containing 0.2% PL and 0.03% GA and no salt had higher turbidity and increased formation of precipitates showing greater turbidity and particle sizes. The Fourier transform infrared spectroscopy confirms the complex coacervate formation of leucine and gum arabic, and rheological measurements suggest the elastic behavior of 0.2% PL and 0.03% GA complex. Overall, the study suggests that complex coacervates of PLs could be one feasible ways of incorporating amino acids in food products. PMID:26471607

  16. Unexpected Diversity of pepA Genes Encoding Leucine Aminopeptidases in Sediments from a Freshwater Lake

    PubMed Central

    Tsuboi, Shun; Yamamura, Shigeki; Imai, Akio; Iwasaki, Kazuhiro

    2016-01-01

    We herein designed novel PCR primers for universal detection of the pepA gene, which encodes the representative leucine aminopeptidase gene, and investigated the genetic characteristics and diversity of pepA genes in sediments of hypereutrophic Lake Kasumigaura, Japan. Most of the amino acid sequences deduced from the obtained clones (369 out of 370) were related to PepA-like protein sequences in the M17 family of proteins. The developed primers broadly detected pepA-like clones associated with diverse bacterial phyla—Alpha-, Beta-, Gamma-, and Deltaproteobacteria, Acidobacteria, Actinobacteria, Aquificae, Chlamydiae, Chloroflexi, Cyanobacteria, Firmicutes, Nitrospirae, Planctomycetes, and Spirochetes as well as the archaeal phylum Thaumarchaeota, indicating that prokaryotes in aquatic environments possessing leucine aminopeptidase are more diverse than previously reported. Moreover, prokaryotes related to the obtained pepA-like clones appeared to be r- and K-strategists, which was in contrast to our previous findings showing that the neutral metalloprotease gene clones obtained were related to the r-strategist genus Bacillus. Our results suggest that an unprecedented diversity of prokaryotes with a combination of different proteases participate in sedimentary proteolysis. PMID:26936797

  17. Studies on spin-trapped radicals in. gamma. -irradiated aqueous L-valine solutions by high-performance liquid chromatography and ESR spectroscopy

    SciTech Connect

    Makino, K.

    1980-05-01

    Short-lived radicals produced in ..gamma..-irradiated aqueous L-valine solution were investigated by the method of spin trapping and subsequently by means of high-performance liquid chromatography combined with ESR spectroscopy. Four spin adducts due to L-valine could be identified. Among them, even the diastereoisomeric spin adducts due to L-valine could be separated. In addition, the effect of pH on the change in the spectra of the diastereoisomers is discussed.

  18. Effect of post-exercise protein-leucine feeding on neutrophil function, immunomodulatory plasma metabolites and cortisol during a 6-day block of intense cycling.

    PubMed

    Nelson, Andre R; Jackson, Lara; Clarke, Jim; Stellingwerff, Trent; Broadbent, Suzanne; Rowlands, David S

    2013-09-01

    Whey protein and leucine ingestion following exercise increases muscle protein synthesis and could influence neutrophil function during recovery from prolonged intense exercise. We examined the effects of whey protein and leucine ingestion post-exercise on neutrophil function and immunomodulators during a period of intense cycling. In a randomized double-blind crossover, 12 male cyclists ingested protein/leucine/carbohydrate/fat (LEUPRO 20/7.5/89/22 g h(-1), respectively) or isocaloric carbohydrate/fat control (CON 119/22 g h(-1)) beverages for 1-3 h post-exercise during 6 days of high-intensity training. Blood was taken pre- and post-exercise on days 1, 2, 4 and 6 for phorbol myristate acetate (PMA)-stimulated neutrophil superoxide (O2 (-)) production, immune cell counts, amino acid and lipid metabolism via metabolomics, hormones (cortisol, testosterone) and cytokines (interleukin-6, interleukin-10). During recovery on day 1, LEUPRO ingestion increased mean concentrations of plasma amino acids (glycine, arginine, glutamine, leucine) and myristic acid metabolites (acylcarnitines C14, myristoylcarnitine; and C14:1-OH, hydroxymyristoleylcarnitine) with neutrophil priming capacity, and reduced neutrophil O2 production (15-17 mmol O2 (-) cell(-1) ± 90 % confidence limits 20 mmol O2 (-) cell(-1)). On day 2, LEUPRO increased pre-exercise plasma volume (6.6 ± 3.8 %) but haematological effects were trivial. LEUPRO supplementation did not substantially alter neutrophil elastase, testosterone, or cytokine concentrations. By day 6, however, LEUPRO reduced pre-exercise cortisol 21 % (±15 %) and acylcarnitine C16 (palmitoylcarnitine) during exercise, and increased post-exercise neutrophil O2 (-) (33 ± 20 mmol O2 (-) cell(-1)), relative to control. Altered plasma amino acid and acylcarnitine concentrations with protein-leucine feeding might partly explain the acute post-exercise reduction in neutrophil function and increased exercise-stimulated neutrophil oxidative burst on

  19. Role of acetohydroxy acid isomeroreductase in biosynthesis of pantothenic acid in Salmonella typhimurium.

    PubMed

    Primerano, D A; Burns, R O

    1983-01-01

    synthases required only methionine for growth (in the presence of leucine, isoleucine, and valine). This and other evidence suggested that the synthesis of pantoic acid by isomeroreductase was blocked by the alpha-acetohydroxy acids and that pantoic acid synthesis was enhanced in the absence of these intermediates, even when the isomeroreductase was at low levels. panE ilvC(+) strains reverted to pantothenate independence. Several of these revertants were shown to have elevated isomeroreductase levels under noninduced and induced conditions; the suppressing mutation in each revertant was shown to be closely linked to ilvC by P22 transduction. This procedure presents a means for obtaining mutants with altered regulation of isomeroreductase. PMID:6401279

  20. Aspartame ingestion with and without carbohydrate in phenylketonuric and normal subjects: effect on plasma concentrations of amino acids, glucose, and insulin.

    PubMed

    Wolf-Novak, L C; Stegink, L D; Brummel, M C; Persoon, T J; Filer, L J; Bell, E F; Ziegler, E E; Krause, W L

    1990-04-01

    Seven subjects homozygous for phenylketonuria (PKU) and seven normal subjects were