3alpha-hydroxysteroid dehydrogenase (B-specific)

In enzymology, a 3alpha-hydroxysteroid dehydrogenase (B-specific) (EC 1.1.1.50) 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 1AFS, 1FJH, 1FK8, 1LWI, 1RAL, 2DKN, and 2FVL.