Hydroxylation of steroids at carbon 21.

Hydroxylation of steroids in V&O at carbon atom 21 by adrenal tissue preparations has previously been reported by Plager and Samuels (l), Hayano and Dorfman (2), and the present authors (3). The former workers described a system consisting of a 20,000 X Q supernatant fraction of beef adrenals which effected hydroxylation in this position of progesterone and ita derivatives in the presence of adenosine triphosphate (ATP) and diphosphopyridine nucleotide (DPN) . The present work defines steroid C-21 hydroxylation aa a reaction involving the microsomal fraction of beef adrenals, reduced triphosphopyridine nucleotide (TPNH), and atmospheric oxygen. Under these conditions progesterone, llfi-hydroxyprogesterone, 17cr-hydroxyprogesterone, and .ll ,17-dihydroxyprogesterone are converted to their respective C-21 hydroxylated derivatives. With the concept of progesterone as a key intermediate in adrenal cortical hormone biogenesis (4), C-21 hydroxylation has the significance of an essential step in the synthesis of steroid hormones by t’his gland.