3-Ketosteroid reductase explained

3-keto-steroid reductase
Ec Number:	1.1.1.270
Cas Number:	42616-29-5
Go Code:	0050576

In enzymology, a 3-keto-steroid reductase is an enzyme that catalyzes the chemical reaction

4alpha-methyl-5alpha-cholest-7-en-3beta-ol + NADP⁺

\rightleftharpoons 4alpha-methyl-5alpha-cholest-7-en-3-one + NADPH + H⁺

Thus, the two substrates of this enzyme are 4alpha-methyl-5alpha-cholest-7-en-3beta-ol and NADP⁺, whereas its 3 products are 4alpha-methyl-5alpha-cholest-7-en-3-one, 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 3beta-hydroxy-steroid:NADP⁺ 3-oxidoreductase. This enzyme is also called 3-KSR. This enzyme participates in biosynthesis of steroids.

References

• Billheimer JT, Alcorn M, Gaylor JL . 1981 . Solubilization and partial purification of a microsomal 3-ketosteroid reductase of cholesterol biosynthesis . Arch. Biochem. Biophys. . 211 . 430–8 . 6946726 . 10.1016/0003-9861(81)90474-4 . 1 .
• Swindell AC, Gaylor JL . 1968 . Investigation of the component reactions of oxidative sterol demethylation. Formation and metabolism of 3-ketosteroid intermediates . J. Biol. Chem. . 243 . 5546–55 . 4387005 . 21 .