In enzymology, 3-oxo-5beta-steroid 4-dehydrogenase () is an enzyme that catalyzes the chemical reaction
For example, the enzyme acts on 5ò-dihydroprogesterone to give progesterone.
This enzyme belongs to the family of oxidoreductases, to be specific, those acting on the CH-CH group of donor with other acceptors. The systematic name of this enzyme class is 3-oxo-5beta-steroid:acceptor Delta4-oxidoreductase. This enzyme is also called 3-oxo-5beta-steroid:(acceptor) Delta4-oxidoreductase. This enzyme participates in 3 metabolic pathways: bile acid biosynthesis, c21-steroid hormone metabolism, and androgen and estrogen metabolism.