Enzyme–substrate complex structures of CYP154C5 shed light on its mode of highly selective steroid hydroxylation

Four enzyme–substrate complex structures of CYP154C5 from N. farcinica with the steroids pregnenolone, progesterone, androstenedione and testosterone bound in the active site of the enzyme are reported, revealing structural determinants for the high regioselectivity and stereoselectivity of CYP154C5 in steroid hydroxylation.