3alpha-hydroxysteroid dehydrogenase (B-specific)

In enzymology, a 3alpha-hydroxysteroid dehydrogenase (B-specific) is an enzyme that catalyzes the chemical reaction


 * androsterone + NAD(P)+ $$\rightleftharpoons$$ 5alpha-androstane-3,17-dione + NAD(P)H + H+

The 3 substrates of this enzyme are androsterone, NAD+, and NADP+, whereas its 4 products are 5alpha-androstane-3,17-dione, 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, more specifically it is part of the group of hydroxysteroid dehydrogenases. The systematic name of this enzyme class is 3alpha-hydroxysteroid:NAD(P)+ oxidoreductase (B-specific). Other names in common use include hydroxyprostaglandin dehydrogenase, 3alpha-hydroxysteroid oxidoreductase, and sterognost 3alpha. This enzyme participates in 3 metabolic pathways: bile acid biosynthesis, c21-steroid hormone metabolism, and androgen and estrogen metabolism.

Structural studies
As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes, , , , , , and.