The Dehydrogenase, 3alpha-hydroxy steroid, with the CAS registry number 9028-56-2, is also known as 3alpha-Hydroxysteroid oxidoreductase. It belongs to the product categories of Oxidoreductases; Specialty Enzymes. Its EINECS number is 232-839-5. Its EC number is 1.1.1.50.  In enzymology, a Dehydrogenase,3a-hydroxy steroid (B-specific) (EC 1.1.1.50) is an enzyme that catalyzes the chemical reaction: androsterone + NAD(P)+ 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. Its storage temperature is 2-8°C.