2-isopropylmalate synthase

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In enzymology, a 2-isopropylmalate synthase (EC is an enzyme that catalyzes the chemical reaction

acetyl-CoA + 3-methyl-2-oxobutanoate + H2O (2S)-2-isopropylmalate + CoA

The 3 substrates of this enzyme are acetyl-CoA, 3-methyl-2-oxobutanoate, and H2O, whereas its two products are (2S)-2-isopropylmalate and CoA.

This enzyme belongs to the family of transferases, specifically those acyltransferases that convert acyl groups into alkyl groups on transfer. The systematic name of this enzyme class is acetyl-CoA:3-methyl-2-oxobutanoate C-acetyltransferase (thioester-hydrolysing, carboxymethyl-forming). Other names in common use include 3-carboxy-3-hydroxy-4-methylpentanoate 3-methyl-2-oxobutanoate-lyase, (CoA-acetylating), alpha-isopropylmalate synthetase, alpha-isopropylmalate synthase, alpha-isopropylmalic synthetase, isopropylmalate synthase, and isopropylmalate synthetase. This enzyme participates in valine, leucine and isoleucine biosynthesis and pyruvate metabolism. It employs one cofactor, potassium.

Structural studies

As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 1SR9.


  • IUBMB entry for
  • BRENDA references for (Recommended.)
  • PubMed references for
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  • Kohlhaw G, Leary TR, Umbarger HE (1969). "Alpha-isopropylmalate synthase from Salmonella typhimurium Purification and properties". J. Biol. Chem. 244: 2218&ndash, 25. PMID 4976555.
  • Webster RE and Gross, SR (1965). "The alpha-isopropylmalate synthetase of Neurospora. I. The kinetics and end product control of alpha-isopropylmalate synthetase function". Biochemistry. 4: 2309&ndash, 2327.
  • Cole FE, Kalyanpur MG, Stevens CM (1973). "Absolute configuration of alpha isopropylmalate and the mechanism of its conversion to beta isopropylmalate in the biosynthesis of leucine". Biochemistry. 12: 3346&ndash, 50. PMID 4270046.

External links

The CAS registry number for this enzyme class is 9030-98-2.

Gene Ontology (GO) codes