Stepwise binding of inhibitors to human cytochrome P450 17A1 and rapid kinetics of inhibition of androgen biosynthesis. (PubMed, J Biol Chem)
Cytochrome P450 (P450) 17A1 catalyzes the 17α-hydroxylation of progesterone and pregnenolone as well as the subsequent lyase cleavage of both products to generate androgens...Here we considered the mechanisms of inhibition of drugs that have been developed to inhibit P450 17A1, including ketoconazole, seviteronel, orteronel, and abiraterone, the only approved inhibitor used for prostate cancer therapy, as well as clotrimazole, known to inhibit P450 17A1...These results are in contrast to inhibitors of P450 3A4, an enzyme with a larger active site in which complete inhibition is not observed with ketoconazole and clotrimazole until the changes are completed. Overall, our the results indicate that both P450 17A1 reactions-17α-hydroxylation and lyase activity-are inhibited by the initial binding of any of these inhibitors, even though subsequent conformational changes occur.