Reaction: a 3-oxo-5α-steroid + NADP+ = a 3-oxo-Δ4-steroid + NADPH + H+
Other name(s): cholestenone 5α-reductase; testosterone Δ4-5α-reductase; steroid 5α-reductase; 3-oxosteroid Δ4-dehydrogenase; 5α-reductase; steroid 5α-hydrogenase; 3-oxosteroid 5α-reductase; testosterone Δ4-hydrogenase; 4-ene-3-oxosteroid 5α-reductase; reduced nicotinamide adenine dinucleotide phosphate:Δ4-3-ketosteroid 5α-oxidoreductase; 4-ene-5α-reductase; Δ4-3-ketosteroid 5α-oxidoreductase; cholest-4-en-3-one 5α-reductase; testosterone 5α-reductase; 3-oxo-5α-steroid 4-dehydrogenase
Systematic name: 3-oxo-5α-steroid:NADP+ Δ4-oxidoreductase
Comments: The enzyme catalyses the conversion of assorted 3-oxo-Δ4 steroids into their corresponding 5α form. Substrates for the mammalian enzyme include testosterone, progesterone, and corticosterone. Substrates for the plant enzyme are brassinosteroids such as campest-4-en-3-one and (22α)-hydroxy-campest-4-en-3-one. cf. EC 1.3.99.5, 3-oxo-5α-steroid 4-dehydrogenase (acceptor).
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37255-34-8
References:
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. Shefer, S., Hauser, S. and Mosbach, E.H. Studies on the biosynthesis of 5α-cholestan-3β-ol. I. Cholestenone 5α-reductase of rat liver. J. Biol. Chem. 241 (1966) 946-952. [PMID: 5907469]
3. Cheng, Y.-J. and Karavolas, H.J. Properties and subcellular distribution of Δ4-steroid (progesterone) 5α-reductase in rat anterior pituitary. Steroids 26 (1975) 57-71. [PMID: 1166484]
4. Sargent, N.S. and Habib, F.K. Partial purification of human prostatic 5α-reductase (3-oxo-5α-steroid:NADP+ 4-ene-oxido-reductase; EC 1.3.1.22) in a stable and active form. J. Steroid Biochem. Mol. Biol. 38 (1991) 73-77. [PMID: 1705142]
5. Quemener, E., Amet, Y., di Stefano, S., Fournier, G., Floch, H.H. and Abalain, J.H. Purification of testosterone 5α-reductase from human prostate by a four-step chromatographic procedure. Steroids 59 (1994) 712-718. [PMID: 7900170]
6. Poletti, A., Celotti, F., Rumio, C., Rabuffetti, M. and Martini, L. Identification of type 1 5α-reductase in myelin membranes of male and female rat brain. Mol. Cell. Endocrinol. 129 (1997) 181-190. [PMID: 9202401]
7. Li, J., Biswas, M.G., Chao, A., Russell, D.W. and Chory, J. Conservation of function between mammalian and plant steroid 5α-reductases. Proc. Natl. Acad. Sci. USA 94 (1997) 3554-3559. [PMID: 9108014]
8. Rosati, F., Bardazzi, I., De Blasi, P., Simi, L., Scarpi, D., Guarna, A., Serio, M., Racchi, M.L. and Danza, G. 5α-Reductase activity in Lycopersicon esculentum: cloning and functional characterization of LeDET2 and evidence of the presence of two isoenzymes. J. Steroid Biochem. Mol. Biol. 96 (2005) 287-299. [PMID: 15993049]