Stereochemistry of hydrogen transfer from pyridine nucleotides catalyzed by delta-4-3-oxosteroid 5-beta-reductase and 3-alpha-hydroxysteroid dehydrogenase from rat liver.

Abstract

The stereochemistry of hydrogen transfer from NADPH in the conversion of Δ4‐3‐oxosteroids into 3‐oxo‐5β‐steroids and from NADH and NADPH in the conversion of 3‐oxo‐5β‐and 3‐oxo‐5α‐steroids into 3α‐hydroxysteroids, catalyzed by rat liver Δ4‐3‐oxosteroid 5β‐reductase and 3α‐hydroxysteroid dehydrogenase, respectively, was studied with C19‐, C21‐, C24‐, and C27‐steroids. In all cases, the hydrogen transferred from the pyridine nucleotides was the 4A‐hydrogen.