Reaction catalyzed by 3alpha-hydroxysteroid 3-dehydrogenase (1.1.1.357)
+
NADPH
+
=
+
+
NADP+
5alpha-dihydroprogesterone
+
NADPH
+
H+
=
allopregnanolone
+
5alpha,20alpha-tetrahydroprogesterone
+
NADP+
