IUBMB Enzyme Nomenclature


Accepted name: Δ4-3-oxosteroid 5β-reductase

Reaction: (1) 5β-cholestan-3-one + NADP+ = cholest-4-en-3-one + NADPH + H+

(2) 17,21-dihydroxy-5β-pregnane-3,11,20-trione + NADP+ = cortisone + NADPH + H+

Glossary: cortisone = 17,21-dihydroxypregn-4-ene-3,11,20-trione

For diagram click here.

Other name(s): 3-oxo-Δ4-steroid 5β-reductase; 5β-reductase; androstenedione 5β-reductase; cholestenone 5β-reductase; cortisone 5β-reductase; cortisone β-reductase; cortisone Δ4-5β-reductase; steroid 5β-reductase; testosterone 5β-reductase; Δ4-3-ketosteroid 5β-reductase; Δ4-5β-reductase; Δ4-hydrogenase; 4,5β-dihydrocortisone:NADP+ Δ4-oxidoreductase; 3-oxo-5β-steroid:NADP+ Δ4-oxidoreductase

Systematic name: 5β-cholestan-3-one:NADP+ 4,5-oxidoreductase

Comments: The enzyme from human efficiently catalyses the reduction of progesterone, androstenedione, 17α-hydroxyprogesterone and testosterone to 5β-reduced metabolites; it can also act on aldosterone, corticosterone and cortisol, but to a lesser extent [8]. The bile acid intermediates 7α,12α-dihydroxy-4-cholesten-3-one and 7α-hydroxy-4-cholesten-3-one can also act as substrates [9].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9029-08-7


1. Forchielli, E. and Dorfman, R.I. Separation of Δ4-5α- and Δ4-5β-hydrogenases from rat liver homogenates. J. Biol. Chem. 223 (1956) 443-448. [PMID: 13376613]

2. Brown-Grant, K., Forchielli, E. and Dorfman, R.I. The Δ4-hydrogenases of guinea pig adrenal gland. J. Biol. Chem. 235 (1960) 1317-1320. [PMID: 13805063]

3. Levy, H.R. and Talalay, P. Enzymatic introduction of double bonds into steroid ring A. J. Am. Chem. Soc. 79 (1957) 2658-2659.

4. Tomkins, G.M. The enzymatic reduction of Δ4-3-ketosteroids. J. Biol. Chem. 225 (1957) 13-24. [PMID: 13416214]

5. Sugimoto, Y., Yoshida, M. and Tamaoki, B. Purification of 5β-reductase from hepatic cytosol fraction of chicken. J. Steroid Biochem. Mol. Biol. 37 (1990) 717-724. [PMID: 2278855]

6. Furuebisu, M., Deguchi, S. and Okuda, K. Identification of cortisone 5β-reductase as Δ4-3-ketosteroid 5β-reductase. Biochim. Biophys. Acta 912 (1987) 110-114. [PMID: 3828348]

7. Okuda, A. and Okuda, K. Purification and characterization of Δ4-3-ketosteroid 5β-reductase. J. Biol. Chem. 259 (1984) 7519-7524. [PMID: 6736016]

8. Charbonneau, A. and The, V.L. Genomic organization of a human 5β-reductase and its pseudogene and substrate selectivity of the expressed enzyme. Biochim. Biophys. Acta 1517 (2001) 228-235. [PMID: 11342103]

9. Kondo, K.H., Kai, M.H., Setoguchi, Y., Eggertsen, G., Sjöblom, P., Setoguchi, T., Okuda, K.I. and Björkhem, I. Cloning and expression of cDNA of human Δ4-3-oxosteroid 5β-reductase and substrate specificity of the expressed enzyme. Eur. J. Biochem. 219 (1994) 357-363. [PMID: 7508385]

[EC created 1961 (EC created 1972, incorporated 2005), modified 2005]

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