this heterologous system supports 17 alpha-hydroxylation of pregnenolone and progesterone with equal efficiency , but catalyzes about five times as much 17,20-lyase activity when 17 alpha-hydroxypregnenolone is the substrate than when 17 alpha-hydroxyprogesterone is the substrate .
C0373704
pregnenolone
C0376260
17 alpha-hydroxypregnenolone