AskDefine | Define isoleucine

Dictionary Definition

isoleucine n : an essential amino acid found in proteins; isomeric with leucine

User Contributed Dictionary



  1. An essential amino acid, C6H13NO2, isomeric with leucine, found in most animal proteins.


essential amino acid; C6H13NO2
  • Spanish: isoleucina

Extensive Definition

Isoleucine (abbreviated as Ile or I) is an α-amino acid with the chemical formula HO2CCH(NH2)CH(CH3)CH2CH3. It is an essential amino acid, which means that humans cannot synthesize it, so it must be part of our diet. Its codons are AUU, AUC and AUA.
With a hydrocarbon side chain, isoleucine is classified as a hydrophobic amino acid. Together with threonine, isoleucine is one of two common amino acids that have a chiral side chain. Four stereoisomers of isoleucine are possible, including two possible diastereomers of L-isoleucine. However, isoleucine present in nature exists in one enantiomeric form, (2S,3S)-2-amino-3-methylpentanoic acid.


As an essential amino acid, isoleucine is not synthesized in animals, hence it must be ingested, usually as a component of proteins. In plants and microorganisms, it is synthesized via several steps, starting from pyruvic acid and alpha-ketoglutarate. Enzymes involved in this biosynthesis include:
  1. Acetolactate synthase (also known as acetohydroxy acid synthase)
  2. Acetohydroxy acid isomeroreductase
  3. Dihydroxyacid dehydratase
  4. Valine aminotransferase

Isomers of isoleucine


Isoleucine can be synthesized in a multistep procedure starting from 2-bromobutane and diethylmalonate. Synthetic isoleucine was originally reported in 1905.


isoleucine in Catalan: Isoleucina
isoleucine in Danish: Isoleucin
isoleucine in German: Isoleucin
isoleucine in Spanish: Isoleucina
isoleucine in Esperanto: Izoleŭcino
isoleucine in French: Isoleucine
isoleucine in Korean: 이소류신
isoleucine in Croatian: Izoleucin
isoleucine in Indonesian: Isoleusin
isoleucine in Italian: Isoleucina
isoleucine in Hebrew: איזולאוצין
isoleucine in Latvian: Izoleicīns
isoleucine in Luxembourgish: Isoleucin
isoleucine in Lithuanian: Izoleucinas
isoleucine in Dutch: Isoleucine
isoleucine in Japanese: イソロイシン
isoleucine in Polish: Izoleucyna
isoleucine in Portuguese: Isoleucina
isoleucine in Russian: Изолейцин
isoleucine in Slovak: Izoleucín
isoleucine in Finnish: Isoleusiini
isoleucine in Swedish: Isoleucin
isoleucine in Turkish: İzolösin
isoleucine in Ukrainian: Ізолейцин
isoleucine in Vlaams: Isoleucine
isoleucine in Chinese: 異亮氨酸
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