IUBMB Enzyme Nomenclature


Accepted name: 3-oxo-5α-steroid 4-dehydrogenase (acceptor)

Reaction: a 3-oxo-5α-steroid + acceptor = a 3-oxo-Δ4-steroid + reduced acceptor

Other name(s): steroid 5α-reductase; 3-oxosteroid Δ4-dehydrogenase; 3-oxo-5α-steroid Δ4-dehydrogenase; steroid Δ4-5α-reductase; Δ4-3-keto steroid 5α-reductase; Δ4-3-oxo steroid reductase; Δ4-3-ketosteroid5α-oxidoreductase; Δ4-3-oxosteroid-5α-reductase; 3-keto-Δ4-steroid-5α-reductase; 5α-reductase; testosterone 5α-reductase; 4-ene-3-ketosteroid-5α-oxidoreductase; Δ4-5α-dehydrogenase; 3-oxo-5α-steroid:(acceptor) Δ4-oxidoreductase; tesI (gene name)

Systematic name: 3-oxo-5α-steroid:acceptor Δ4-oxidoreductase

Comments: A flavoprotein. This bacterial enzyme, characterized from Comamonas testosteroni, is involved in androsterone degradation. cf. EC, 3-oxo-5α-steroid 4-dehydrogenase (NADP+).

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9036-43-5


1. Levy, H.R. and Talalay, P. Bacterial oxidation of steroids. II. Studies on the enzymatic mechanisms of ring A dehydrogenation. J. Biol. Chem. 234 (1959) 2014-2021. [PMID: 13673006]

2. Florin, C., Kohler, T., Grandguillot, M. and Plesiat, P. Comamonas testosteroni 3-ketosteroid-Δ4(5α)-dehydrogenase: gene and protein characterization. J. Bacteriol. 178 (1996) 3322-3330. [PMID: 8655514]

3. Horinouchi, M., Hayashi, T., Yamamoto, T. and Kudo, T. A new bacterial steroid degradation gene cluster in Comamonas testosteroni TA441 which consists of aromatic-compound degradation genes for seco-steroids and 3-ketosteroid dehydrogenase genes. Appl. Environ. Microbiol. 69 (2003) 4421-4430. [PMID: 12902225]

[EC created 1965, modified 2012]

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