3beta-hydroxy-5alpha-steroid dehydrogenase

In enzymology, a 3β-hydroxy-5α-steroid dehydrogenase (EC 1.1.1.278) is an enzyme that catalyzes the chemical reaction

3β-hydroxy-5α-pregnane-20-one + NADP⁺ ${\displaystyle \rightleftharpoons }$ 5α-pregnan-3,20-dione + NADPH + H⁺

3β-hydroxy-5α-steroid dehydrogenase
Identifiers
EC no.	1.1.1.278
CAS no.	9015-81-0
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

Thus, the two substrates of this enzyme are 3β-hydroxy-5α-pregnane-20-one (allopregnanolone) and NADP⁺, whereas its 3 products are 5α-pregnan-3,20-dione, 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 3β-hydroxy-5α-steroid:NADP⁺ 3-oxidoreductase.