IUBMB Enzyme Nomenclature


Accepted name: 2-hydroxyhexa-2,4-dienoate hydratase

Reaction: 4-hydroxy-2-oxohexanoate = (2Z,4Z)-2-hydroxyhexa-2,4-dienoate + H2O

Other name(s): tesE (gene name); hsaE (gene name)

Systematic name: 4-hydroxy-2-oxohexanoate hydro-lyase [(2Z,4Z)-2-hydroxyhexa-2,4-dienoate-forming]

Comments: This enzyme catalyses a late step in the bacterial steroid degradation pathway. The product, 4-hydroxy-2-oxohexanoate, forms a 2-hydroxy-4-hex-2-enolactone under acidic conditions.

Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, Metacyc, PDB, CAS registry number:


1. Horinouchi, M., Hayashi, T., Koshino, H., Kurita, T. and Kudo, T. Identification of 9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid, 4-hydroxy-2-oxohexanoic acid, and 2-hydroxyhexa-2,4-dienoic acid and related enzymes involved in testosterone degradation in Comamonas testosteroni TA441. Appl. Environ. Microbiol. 71 (2005) 5275-5281. [PMID: 16151114]

[EC created 2012]

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