20alpha-hydroxysteroid dehydrogenase

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In enzymology, a 20alpha-hydroxysteroid dehydrogenase (EC is an enzyme that catalyzes the chemical reaction

17alpha,20alpha-dihydroxypregn-4-en-3-one + NAD(P)+ 17alpha-hydroxyprogesterone + NAD(P)H + H+

The 3 substrates of this enzyme are 17alpha,20alpha-dihydroxypregn-4-en-3-one, NAD+, and NADP+, whereas its 4 products are 17alpha-hydroxyprogesterone, NADH, NADPH, and H+.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 20alpha-hydroxysteroid:NAD(P)+ 20-oxidoreductase. Other names in common use include 20alpha-hydroxy steroid dehydrogenase, 20alpha-hydroxy steroid dehydrogenase, 20alpha-HSD, and 20alpha-HSDH. This enzyme participates in c21-steroid hormone metabolism.

Structural studies

As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 1MRQ, 1Q13, and 1Q5M.


  • IUBMB entry for
  • BRENDA references for (Recommended.)
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  • Shikita M, Inano H, Tamaoki B (1967). "Further studies on 20-alpha-hydroxysteroid dehydrogenase of rat testes". Biochemistry. 6: 1760&ndash, 4. PMID 4382486.
  • Strickler RC, Tobias B, Covey DF (1981). "Human placental 17 beta-estradiol dehydrogenase and 20 alpha-hydroxysteroid dehydrogenase. Two activities at a single enzyme active site". J. Biol. Chem. 256: 316&ndash, 21. PMID 6935192.

External links

The CAS registry number for this enzyme class is 9040-08-8.

Gene Ontology (GO) codes