Cleavage of cholesterol side chain associated with cytochrome P-450, flavoprotein, and nonheme iron-protein derived from the bovine adrenal cortex.

Cholesterol side chain cleavage has been shown to be dependent on the electron carrier chain involving a cytochrome P-450 reductase system, flavoprotein and nonheme iron-protein of the ferredoxin type, and the oxygen-activating cytochrome P-450. The reaction is markedly inhibited by carbon monoxide. The cytochrome oxidase system inhibits the cleavage reaction by diverting the flow of electrons through the cytochrome oxidase pathway. Inhibition is reversed by cyanide. Steroid products resulting from the cleavage reaction are pregnenolone, progesterone, 11 -deoxycorticosterone, and corticosterone. These products were isolated and identified by paper chromatographic techniques and recrystallization to radiochemical homogeneity.