<prompt> The rate-limiting step in the synthesis of coisol is catalyzed by21-Hydroxylase3b-Hydroxysteroid dehydrogenaseCholesterol side-chain cleavage enzyme11b-Hydroxylase  <response>: The first and rate-limiting step in all steroid biosynthesis is catalyzed by cholesterol sidechain cleavage enzyme, resulting in pregnenolone and isocaproic acid. 