IUBMB Enzyme Nomenclature


Accepted name: (R)-citramalate synthase

Reaction: acetyl-CoA + pyruvate + H2O = CoA + (2R)-2-hydroxy-2-methylbutanedioate

Glossary: (–)-citramalate = (2R)-2-methylmalate = (2R)-2-hydroxy-2-methylbutanedioate
α-ketoisovalerate = 3-methyl-2-oxobutanoate
α-ketobutyrate = 2-oxobutanoate
α-ketoisocaproate = 4-methyl-2-oxopentanoate
α-ketopimelate = 2-oxohexanoate
α-ketoglutarate = 2-oxoglutarate

Other name(s): CimA

Comments: One of the enzymes involved in a novel pyruvate pathway for isoleucine biosynthesis that is found in some, mainly archaeal, bacteria [1,2]. The enzyme can be inhibited by isoleucine, the end-product of the pathway, but not by leucine [2]. The enzyme is highly specific for pyruvate as substrate, as the 2-oxo acids 3-methyl-2-oxobutanoate, 2-oxobutanoate, 4-methyl-2-oxopentanoate, 2-oxohexanoate and 2-oxoglutarate cannot act as substrate [1,2].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:


1. Howell, D.M., Xu, H. and White, R.H. (R)-Citramalate synthase in methanogenic archaea. J. Bacteriol. 181 (1999) 331-333. [PMID: 9864346]

2. Xu, H., Zhang, Y., Guo, X., Ren, S., Staempfli, A.A., Chiao, J., Jiang, W. and Zhao, G. Isoleucine biosynthesis in Leptospira interrogans serotype 1ai strain 56601 proceeds via a threonine-independent pathway. J. Bacteriol. 186 (2004) 5400-5409. [PMID: 15292141]

[EC created 2007]

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