Steroid C-21-hydroxylation by dog adrenal microsomes

1,2-3H121-Deoxycortisol (1) 1,2-3H21-deoxycortisone and 1,2-3H-17OH-progesterone were incubated separately with dog adrenal microsomes. With substrates concentrations of 30 and 150 nmoles all the substrates were hydroxylated at C-21 to a similar extent. This result suggests that 21-deoxycortisol could be an intermediate in the biosynthesis of cortisol provided it is avilable in vivo.