Purification and comparative characterization of cytochrome P-450scc from porcine adrenocortical mitochondria.

Abstract 1. 1Cytochrome P-450scc (cholesterol side-chain cleavage enzyme) was purified from porcine adrenocortical mitochondria. 2. 2. The purified cytochrome P-450scc was found to be homogeneous on SDS-polyacrylamide gel electrophoresis. 3. 3. The heme content of the purified enzyme was 20.6nmol/mg protein. 4. 4. The enzymatic activity of the reconstituted cytochrome P-450scc-linked monooxygenase system amounted to 7.8 nmol of pregnenolone formed per nmole of P-450 per minute, with cholesterol as a substrate. 5. 5. The amino acid sequence of the ammo-terminal region of the cytochrome P-450scc and the amino acid residue at the carboxyl terminal were determined and compared with those of other mammalian cytochromes P-450scc.