IUBMB Enzyme Nomenclature


Accepted name: crotonobetainyl-CoA reductase

Reaction: γ-butyrobetainyl-CoA + electron-transfer flavoprotein = crotonobetainyl-CoA + reduced electron-transfer flavoprotein

Glossary: γ-butyrobetainyl-CoA = 4-(trimethylammonio)butanoyl-CoA
crotonobetainyl-CoA = (E)-4-(trimethylammonio)but-2-enoyl-CoA

Other name(s): caiA (gene name)

Systematic name: γ-butyrobetainyl-CoA:electron-transfer flavoprotein 2,3-oxidoreductase

Comments: The enzyme has been purified from the bacterium Escherichia coli O44 K74, in which it forms a complex with EC, L-carnitine CoA-transferase. The electron donor is believed to be an electron-transfer flavoprotein (ETF) encoded by the fixA and fixB genes.

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


1. Roth, S., Jung, K., Jung, H., Hommel, R.K. and Kleber, H.P. Crotonobetaine reductase from Escherichia coli - a new inducible enzyme of anaerobic metabolization of L(–)-carnitine. Antonie Van Leeuwenhoek 65 (1994) 63-69. [PMID: 8060125]

2. Preusser, A., Wagner, U., Elssner, T. and Kleber, H.P. Crotonobetaine reductase from Escherichia coli consists of two proteins. Biochim. Biophys. Acta 1431 (1999) 166-178. [PMID: 10209289]

3. Elssner, T., Hennig, L., Frauendorf, H., Haferburg, D. and Kleber, H.P. Isolation, identification, and synthesis of γ-butyrobetainyl-CoA and crotonobetainyl-CoA, compounds involved in carnitine metabolism of E. coli. Biochemistry 39 (2000) 10761-10769. [PMID: 10978161]

4. Walt, A. and Kahn, M.L. The fixA and fixB genes are necessary for anaerobic carnitine reduction in Escherichia coli. J. Bacteriol. 184 (2002) 4044-4047. [PMID: 12081978]

[EC created 2017]

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