Progesterone 5alpha reductase

In enzymology, a progesterone 5alpha-reductase (EC 1.3.1.30) is an enzyme that catalyzes the chemical reaction

5alpha-pregnan-3,20-dione + NADP⁺ ⇌ progesterone + NADPH + H⁺

Thus, the two substrates of this enzyme are 5alpha-pregnan-3,20-dione and NADP⁺, whereas its 3 products are progesterone, NADPH, and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 5alpha-pregnan-3,20-dione:NADP+ 5-oxidoreductase. Other names in common use include steroid 5-alpha-reductase, and Delta4-steroid 5alpha-reductase (progesterone). This enzyme participates in c21-steroid hormone metabolism.