Search results for "Isoleucine"
showing 10 items of 38 documents
Pitfalls to be considered on the metabolomic analysis of biological samples by HR-MAS
2014
HR-MAS (High-Resolution Magic AngleSpinning) is considered a powerfultechnique for metabolomic studies ofbiological samples that provides “intact”tissue spectra (Cheng et al., 1998; Waterset al., 2000; Sitter et al., 2002; Martinez-Bisbal et al., 2004; Payne et al., 2006;Coen et al., 2007; Bathen et al., 2010).The performance of HR-MAS, fol-lowed by quantitative histopathology hasdemonstrated that, despite some changes,HR-MAS can preserve approximately thetissue histopathologic features producingwell-resolved spectra of cellular metabo-lites (Cheng et al., 2000). Nevertheless,therearesomeaspectsarousedintheliter-ature about the possible biochemical andstructural changes that can occur durin…
Determinants of Substrate Specificity in the NS3 Serine Proteinase of the Hepatitis C Virus
1997
AbstractProcessing of the nonstructural polyprotein of the hepatitis C virus (HCV) requires the serine-type proteinase located in the amino-terminal domain of NS3. To identify residues within NS3 determining substrate specificity, a mutation analysis was performed. Using sequence alignments and three-dimensional structure predictions, amino acids assumed to be important for specificity were replaced and the enzymes were tested in an intracellulartrans-processing assay for their effects on cleavage of an NS4B-5B substrate. For some of the substitutions at positions 133, 134, 135, 136, 138, 152, 155, 157, and 169, slightly reduced processing efficiencies were observed but in no case was the s…
Classification of vegetable oils according to their botanical origin using amino acid profiles established by direct infusion mass spectrometry.
2007
Amino acid profiles, established by direct infusion mass spectrometry, have been used to classify vegetable oils according to their botanical origin. The proteins present in hazelnut, sunflower, corn, soybean, olive, avocado, peanut and grapeseed oils were precipitated with acetone, and the residue was hydrolyzed in acid medium, diluted in a hydrochloric acid/ethanol mixture, and infused into the mass spectrometer. The spectra of the hydrolyzed protein extracts showed [M+H]+ ions of the following amino acids: glycine, alanine, serine, proline, valine, threonine, cysteine, isoleucine + leucine, aspartic acid, lysine, glutamic acid, methionine, histidine, phenylalanine, arginine and tyrosine.…
More about sampling and estimation of mercaptans in air samples
2013
[EN] Several strategies have been developed for sampling and determination of volatile thiols. The selectivity and sensitivity of the proposed methodologies are achieved by using a specific derivatizing reagent. The different procedures assayed are based on air sampling followed by derivatization of the analytes with OPA and isoleucine in alkaline solution. The derivatization products are separated and determined by liquid chromatography and fluorescence detection. To start, the derivatization conditions and stability of the derivates have been studied in order to establish the storage conditions. In general, the strategies studied consisted on trapping and detivatization the thiol compound…
The Impact of Amino Acids on Postprandial Glucose and Insulin Kinetics in Humans
2020
Different amino acids (AAs) may exert distinct effects on postprandial glucose and insulin concentrations. A quantitative comparison of the effects of AAs on glucose and insulin kinetics in humans is currently lacking. PubMed was queried to identify intervention studies reporting glucose and insulin concentrations after acute ingestion and/or intravenous infusion of AAs in healthy adults and those living with obesity and/or type 2 diabetes (T2DM). The systematic literature search identified 55 studies that examined the effects of l-leucine, l-isoleucine, l-alanine, l-glutamine, l-arginine, l-lysine, glycine, l-proline, l-phenylalanine, l-glutamate, branched-chain AAs (i.e., l-leucine, l-iso…
Synthesis of peptides with α,β-dehydroamino acids, VI. Synthesis ofN-benzyloxycarbonyl andN-trifluoroacetyl dipeptides of α,β-dehydro-butyrine, -vali…
1988
Condensation of Z- and TFA-amino acid amides with 2-oxo-acids, namely butanoic, 3-methylbutanoic, 4-methylpentanoic, and (3RS)-3-methylpentanoic acid, yields (in the presence of p-toluenesulfonic acid as a catalyst) Z- and TFA-dipeptides with C-terminal ΔAbu2) (1–4), ΔVal (5–8), ΔLeu (9–11), and ΔIle (12–15) (Table 1).
Die Bildung höherer Alkohole bei Aminosäuremangelmutanten von Saccharomyces cerevisiae III. Höhere Alkohole als Nebenprodukte der Aminosäuresynthese
1975
Summary The formation of higher alcohols as byproducts of the synthesis of threonine, isoleucine and valine was investigated using isogenic haploid and diploid mutant strains of Saccharomyces cerevisiae . Genetic markers were ade 2, leu 1. The growth rate, the formation of ethanol, the amino acid metabolism and the formation of higher alcohols were determined during fermentations in a synthetic medium. n-Propanol-1, 2-methylbutanol-l and isobutanol were synthesized parallel to ethanol formation during exponential and stationary growth phase. However, the formation of 3-methylbutanol-l from leucine was restricted to the exponential phase. A comparison of haploid and diploid strains revealed,…
Amino acid substitutions enhancing thermostability of Bacillus polymyxa beta-glucosidase A
1996
Mutations enhancing the thermostability of β-glucosidase A of Bacillus polymyxa, a family 1 glycosyl hydrolase, have been obtained after hydroxylamine mutagenesis of a plasmid containing the bglA gene, transformation of Escherichia coli with the mutagenized plasmid, and identification of transformant colonies that showed β-glucosidase activity after a thermal treatment that inactivated the wild-type enzyme. Two additive mutations have been characterized that cause replacement of glutamate at position 96 by lysine and of methionine at position 416 by isoleucine respectively. The thermoresistant mutant enzymes showed increased resistance to other denaturing agents, such as pH and urea, while …
Comparison of α-acetolactate synthase and α-acetolactate decarboxylase in Lactococcus spp. and Leuconostoc spp.
1994
Cell-free extracts of Leuconostoc and Lactococcus species were tested for their alpha-acetolactate synthase and alpha-acetolactate decarboxylase activities. In Leuconostoc mesenteroides subsp. cremoris, Leuconostoc mesenteroides subsp. mesenteroides and Leuconostoc lactis, the Km of alpha-acetolactate synthase for pyruvate was close to 10 mM whereas it was 30 mM in Lactococcus lactis subsp. lactis biovar. diacetylactis. The Km of alpha-acetolactate decarboxylase for alpha-acetolactic acid was very low (0.3 mM) in Leuconostoc species in comparison to Lactococcus lactis subsp. lactis biovar. diacetylactis (60 mM). In the latter bacterium, alpha-acetolactate decarboxylase showed a sigmoidal de…
A second family with familial AD and the V717L APP mutation has a later age at onset
2006
Four mutations have been reported at the 717 codon of the amyloid precursor protein (APP), with valine substituted by isoleucine, glycine, phenylalanine, and leucine. While several families with the isoleucine substitution have been described, the other substitutions have been reported in only one family each worldwide. A family with the V717L APP mutation has been previously reported,1 with a mean age at onset of 38 years (range 35 to 39), based on four affected family members, and a mean age at death of 46 years (range 40 to 50). We have identified a second family with a later mean age at onset of 50 years (range 48 to 57) and mean age at death of 61 years (range 57 to 68). Family 171 is …