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Related to isoleucine: valine, methionine


isoleucine (īˌsəlo͞oˈsēn), organic compound, one of the 20 amino acids commonly found in animal proteins. Only the L-stereoisomer appears in mammalian protein. It is one of several essential amino acids needed in the diet; human beings cannot synthesize it from simpler metabolites. Young adults need about 20 mg of this amino acid per day per kg (or about 8 mg per lb) of body weight. Isoleucine can be degraded into simpler compounds by the enzymes of the body. In a rare, inherited disorder called maple syrup urine disease, a nonfunctional enzyme in the common pathway of isoleucine, leucine, and valine degradation causes the buildup of certain metabolites in the urine, resulting in the characteristic odor from which the disease derives its name. Once isoleucine is incorporated into protein, it contributes to the structure of protein by the tendency of its side chain (composed only of carbon and hydrogen) to seek an environment consisting of similar side chains, like those of leucine, valine, tryptophan, and phenylalanine, and to exclude water. This hydrophobic property is analogous to that which prevents oil from dissolving in water. The tendency for these hydrophobic residues to associate with one another is evidently quite important in determining the bending and folding (tertiary structure) of the peptide chain characteristically seen in every protein. Isoleucine was isolated from beet sugar molasses in 1904.

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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



α-amino-β-methylvaleric acid, C2H5CH(CH3)-CH(NH2)COOH, an amino acid discovered by F. Ehrlich (1904), among the decomposition products of fibrin protein; one of the group of branched-carbon-chain monoamino aliphatic monocarboxylic acids.

Isoleucine is present in proteins in only small amounts, but it is an essential amino acid for man, animals, and many microorganisms and must be introduced with food. The daily human requirement of isoleucine is about 1.5 -2 g.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


C6H13O2 An essential monocarboxylic amino acid occurring in most dietary proteins.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
In the past, traditional de novo antibody sequencing using the Next-Generation Sequencing (NGS) technique could not precisely distinguish leucine and isoleucine due to their unspecific and random distribution, the same molecular mass, and similar chemical property.
In the present study, amino acids, including glycine, asparagine, glutamate, threonine, proline, valine, methionine, isoleucine, and histidine, were down-regulated in the HS group, pointing to increased conversion of these metabolites into glucose to maintain homeostasis and supply energy during periods of NEB in dairy cows [22].
The treated group had also reversed direction of changes in some of metabolites levels, including alanine, glutamine, serine, glucose, asparagine, isoleucine, valine, carnitine, isobutyrate and pantothenate compared to AD group which showed the effectiveness of the lavender extract on the improvement of AD rats.
Amino acid g amino acid per 100 g of protein (mean [+ or -] SD) Aspartic acid 8.43 [+ or -] 0.29 Glutamic acid 16.96 [+ or -] 1.34 Serine 3.31 [+ or -] 0.17 Histidine 2.99 [+ or -] 0.09 Glycine 5.64 [+ or -] 0.49 Threonine 5.33 [+ or -] 0.34 Alanine 6.59 [+ or -] 0.41 Arginine 5.88 [+ or -] 0.13 Tyrosine 5.44 [+ or -] 0.16 Valine 4.82 [+ or -] 0.26 Phenylalanine 4.45 [+ or -] 0.12 Isoleucine 5.24 [+ or -] 0.09 Leucine 8.87 [+ or -] 0.87 Lysine 9.84 [+ or -] 0.33 Methionine 2.93 [+ or -] 0.07 Tryptophan 0.59 [+ or -] 0.004 Muscle protein content 67% Table 2.
Peak Retention Amino acids Linear time (min) range ([micro]g/L) 1 8.87 Serine 8.45-101.46 2 10.98 Treonine 8.51-102.06 3 13.49 Arginine 8.36 100.28 4 14.26 Alanine 8.76-105.14 5 16.66 Proline 8.67-104.00 6 24.99 Valine 8.36-100.37 7 25.87 Methionine 8.35-100.19 8 26.95 Cysteine 8.27- 99.30 9 28.29 Isoleucine 8.29 -99.52 10 28.88 Tryptophan 8.30-99.54 Peak A b([10.
Major limitations include incomplete information of all common amino acids and inability to separate leucine from isoleucine and other isobaric analytes.
However, one has to point out the lower content of sulphur amino acids and isoleucine in all fish species analyzed as well as the lower valine content in wels catfish.
The increases for T2DM in leucine, isoleucine, valine, and 3-HIB were significant after BMI adjustment, but those in tyrosine and phenylalanine were not.
Isoleucine and leucine were detected as separate peaks in the MDC-CC analysis and replication cohort, and as one peak in the WLWM analysis, thus isoleucine and leucine will be referred as isoleucine/leucine in the WLWM cohort.
Further biochemical study with plasma amino acid analysis showed a leucine level of 4163.6 [micro]mol/L (reference values: 42-133.1 [micro]mol/L), isoleucine of 499.8 [micro]mol/L (15.1-74.9 [micro]mol/L), and valine of 784.3 [micro]mol/L (73.6--273.1 [micro]mol/L).
Maple syrup urine disease (MSUD) is an autosomal recessive inherited metabolic disease caused by decreased enzyme activity of branched-chain alpha-ketoacid dehydrogenase complex (BCKDC), responsible for catabolism of leucine (leu), valine (val), and isoleucine (isoleu).
Several dominant metabolites in serum were identified, including amino acids such as isoleucine, leucine, proline, glutamate, methionine, phenylalanine, and 1-methylhistidine; organic acids such as 3-hydroxybutyrate, and citrate; waste metabolites such as methanol and formate; and glycerol and glucose.