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| Leucine | |
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| IUPAC name | (S)-2-amino-4-methyl-pentanoic acid |
| Identifiers | |
| CAS number | 61-90-5 |
| PubChem | |
| SMILES |
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| Properties | |
| Molecular formula | C6H13NO2 |
| Molar mass | 131.17 g mol−1 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
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Leucine (abbreviated as Leu or L)1 is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CH(CH3)2. It is an essential amino acid, which means that humans cannot synthesise it. Its codons are UUA, UUG, CUU, CUC, CUA, and CUG. With a hydrocarbon side chain, leucine is classified as a hydrophobic amino acid. It has an isobutyl R group. Leucine is a major component of the sub units in ferritin, astacin and other 'buffer' proteins.
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Biosynthesis
As an essential amino acid, leucine is not synthesized in animals, hence it must be ingested, usually as a component of proteins. It is synthesized in plants and microorganisms via several steps starting from pyruvic acid. The initial part of the pathway also leads to valine. The intermediate α-ketovalerate is converted to α-isopropylmalate and then β-isopropylmalate, which is dehydrogenated to α-ketoisocaproate, which in the final step undergoes reductive amination. Enzymes involved in a typical leucine biosynthesis include2
- Acetolactate synthase,
- Acetohydroxy acid isomeroreductase,
- Dihydroxyacid dehydratase,
- α-Isopropylmalate synthase,
- α-Isopropylmalate isomerase,
- Leucine aminotransferase.
Biological Uses
As a dietary supplement, leucine has been found to slow the degradation of muscle tissue by increasing the synthesis of muscle proteins.3 Leucine is utilized in the liver, adipose tissue, and muscle tissue. In adipose and muscle tissue, leucine is used in the formation of sterols, and the combined usage of leucine in these two tissues is seven times greater than its use in the liver.4
Chemical properties
Racemic leucine had been subjected to circularly polarized synchrotron radiation in order to better understand the origin of biomolecular asymmetry. An enantiomeric enhancement of 2.6 % had been induced, indicating a photochemical origin of biomolecules' homochirality.5
Food additive
As a food additive L-Leucine has E number E641 and is classified as a flavour enhancer.
See also
- Leucines, description of the isomers of leucine
- Photo-reactive leucine
References
- ^ IUPAC-IUBMB Joint Commission on Biochemical Nomenclature. "Nomenclature and Symbolism for Amino Acids and Peptides". Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc. Retrieved on 2007-05-17.
- ^ Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN 1-57259-153-6.
- ^ L. Combaret, et al Human Nutrition Research Centre of Clermont-Ferrand. "A leucine-supplemented diet restores the defective postprandial inhibition of proteasome-dependent proteolysis in aged rat skeletal muscle". Journal of Physiology Volume 569, issue 2, p. 489-499. Retrieved on 2008-03-25.
- ^ J. Rosenthal, et al Department of Medicine, University of Toronto, Toronto, Canada. "Metabolic fate of leucine: A significant sterol precursor in adipose tissue and muscle". American Journal of Physiology Vol. 226, No. 2, p. 411-418. Retrieved on 2008-03-25.
- ^ Meierhenrich: Amino acids and the asymmetry of life, Springer-Verlag, 2008, ISBN 978-3-540-76885-2
External links
- Leucine biosynthesis
- Leucine content in food
- Computational Chemistry Wiki
- Leucine prevents muscle loss in rats
- Leucine helps regulate appetite in rats
- Combined ingestion of protein and free leucine with carbohydrate increases postexercise muscle protein synthesis in vivo in male subjects
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Wikipedia content modification information:
- This page was last modified on 29 November 2008, at 16:31.
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