Chemical structure of Leucine

Chemical structure of Leucine


Systematic (IUPAC) name
(S)-2-amino-4-methyl-pentanoic acid
CAS number 61-90-5
PubChem         6106
Chemical data
Formula C6H13NO2 
Molar mass 131.18 g/mol
Complete data

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.

Biosynthesis Edit

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 include[2]

Biological UsesEdit

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]

Food additive Edit

As a food additive L-Leucine has E number E641 and is classified as an flavour enhancer.

See also Edit


  1. 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.
  2. Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN 1-57259-153-6.
  3. 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.
  4. 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.

External links Edit


cs:Leucin da:Leucin de:Leucin es:Leucina eo:Leŭcino fr:Leucine ko:류신 hr:Leucin id:Leusin it:Leucina he:לאוצין lv:Leicīns lb:Leucin lt:Leucinas nl:Leucine ja:ロイシン no:Leucin pl:Leucyna pt:Leucina ru:Лейцин sk:Leucín fi:Leusiini sv:Leucin tr:Lösin uk:Лейцин vls:Leucine zh:亮氨酸

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