The rate-limiting step in the synthesis of coisol is catalyzed by: (A) 21-Hydroxylase, (B) 3b-Hydroxysteroid dehydrogenase, (C) Cholesterol side-chain cleavage enzyme, (D) 11b-Hydroxylase
Answer is C. The first and rate-limiting step in all steroid biosynthesis is catalyzed by cholesterol sidechain cleavage enzyme, resulting in pregnenolone and isocaproic acid.