title: Synthesis of aldosterone by a reconstituted system of cytochrome P-45011 beta from bovine adrenocortical mitochondria.
abstract: When corticosterone was incubated with cytochrome P-45011 beta purified from bovine adrenocortical mitochondria in the presence of adrenodoxin, NADPH-adrenodoxin reductase and an NADPH generating system, aldosterone as well as 18-hydroxycorticosterone were formed with turnover numbers of 0.23 and 1.1 nmol/min/nmol P-450, respectively. Phospholipids extracted from adrenocortical mitochondria remarkably enhanced the activity of aldosterone formation by the cytochrome P-45011 beta-reconstituted system. The apparent Km and turnover number were estimated to be 6.9 microM and 2.0 nmol/min/nmol P-450 for aldosterone formation in the presence of the lipidic extract. When 18-hydroxycorticosterone was tested as a substrate, cytochrome P-45011 beta showed catalytic activity for aldosterone synthesis with an apparent Km and turnover number of 325 microM and 5.3 nmol/min/nmol P-450, respectively. Carbon monoxide and metyrapone inhibited the production of aldosterone from corticosterone and that from 18-hydroxycorticosterone. These results suggest that conversion of corticosterone and of 18-hydroxycorticosterone to aldosterone occurs through P-45011 beta-catalyzed reaction.
mesh_terms: D000302:Adrenal Cortex / Q000378:metabolism*; D000450:Aldosterone / Q000096:biosynthesis*; D000818:Animals; D002248:Carbon Monoxide / Q000494:pharmacology; D002308:Cardiolipins / Q000502:physiology; D002374:Catalase / Q000378:metabolism; D002417:Cattle; D002474:Cell-Free System; D003345:Corticosterone / Q000096:biosynthesis; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D007700:Kinetics; D008055:Lipids / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism*; D010743:Phospholipids / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D002308:Cardiolipins; D008055:Lipids; D010743:Phospholipids; D011725:Pyridines; C013109:metapyrone; D000450:Aldosterone; D002248:Carbon Monoxide; D003577:Cytochrome P-450 Enzyme System; D002374:Catalase; D013482:Superoxide Dismutase; D003345:Corticosterone