EC - 3-oxo-5α-steroid 4-dehydrogenase (NADP+)

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IntEnz Enzyme Nomenclature


Accepted name:
3-oxo-5α-steroid 4-dehydrogenase (NADP+)
Other names:
3-oxosteroid 5α-reductase
3-oxosteroid Δ4-dehydrogenase
4-ene-3-oxosteroid 5α-reductase
Δ4-3-ketosteroid 5α-oxidoreductase
cholest-4-en-3-one 5α-reductase
reduced nicotinamide adenine dinucleotide phosphate:Δ4-3-ketosteroid 5α-oxidoreductase
steroid 5α-hydrogenase
steroid 5α-reductase
testosterone 5α-reductase
testosterone Δ4-5α-reductase
testosterone Δ4-hydrogenase
cholestenone 5α-reductase
3-oxo-5α-steroid 4-dehydrogenase
Systematic name:
3-oxo-5α-steroid:NADP+ Δ4-oxidoreductase



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, 3-oxo-5α-steroid 4-dehydrogenase (acceptor).

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ERGO , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0047751
CAS Registry Number: 37255-34-8
UniProtKB/Swiss-Prot: (21) [show] [UniProt]


  1. Levy, H.R., Talalay, P.
    Bacterial oxidation of steroids. II. Studies on the enzymatic mechanism of ring A dehydrogenation.
    J. Biol. Chem. 234: 2014-2021 (1959). [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: 946-952 (1966). [PMID: 5907469]
  3. Cheng, Y. J., Karavolas, H. J.
    Properties and subcellular distribution of delta4-steroid (progesterone) 5alpha-reductase in rat anterior pituitary.
    Steroids 26: 57-71 (1975). [PMID: 1166484]
  4. Sargent, N. S., Habib, F. K.
    Partial purification of human prostatic 5 alpha-reductase (3-oxo-5 alpha-steroid:NADP+ 4-ene-oxido-reductase; EC in a stable and active form.
    J. Steroid Biochem. Mol. Biol. 38: 73-77 (1991). [PMID: 1705142]
  5. Quemener, E., Amet, Y., di Stefano, S., Fournier, G., Floch, H. H., Abalain, J. H.
    Purification of testosterone 5 alpha-reductase from human prostate by a four-step chromatographic procedure.
    Steroids 59: 712-718 (1994). [PMID: 7900170]
  6. Poletti, A., Celotti, F., Rumio, C., Rabuffetti, M., Martini, L.
    Identification of type 1 5alpha-reductase in myelin membranes of male and female rat brain.
    Mol. Cell. Endocrinol. 129: 181-190 (1997). [PMID: 9202401]
  7. Li, J., Biswas, M. G., Chao, A., Russell, D. W., Chory, J.
    Conservation of function between mammalian and plant steroid 5alpha-reductases.
    Proc. Natl. Acad. Sci. U.S.A. 94: 3554-3559 (1997). [PMID: 9108014]
  8. Rosati, F., Bardazzi, I., De Blasi, P., Simi, L., Scarpi, D., Guarna, A., Serio, M., Racchi, M. L., Danza, G.
    5alpha-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: 287-299 (2005). [PMID: 15993049]

[EC created 1972, modified 2012]