Effect of phospholipid on aldosterone biosynthesis by a cytochrome P-450(11) beta-reconstituted system

Effect of phospholipid on aldosterone synthesis catalyzed by a cytochrome P-450(11)beta-reconstituted system was examined. Corticosterone was incubated with P-450(11)beta in the presence of phosphatidylcholine, phosphatidylethanolamine, cardiolipin, phosphatidylinositol, or phosphatidylserine. These phospholipids stimulated the rate of aldosterone- and 18-hydroxycorticosterone-synthesis, although the mode of stimulation by neutral phospholipids was different from that by acidic phospholipids. In the presence of a phospholipid mixture containing the lipids in the same molar ratios as found in adrenocortical mitochondria, the rate of production of aldosterone increased 10-fold over the rate without the lipids, and that of 18-hydroxycorticosterone increased 3-fold. The maximal synthetic rates of aldosterone and 18-hydroxycorticosterone were 2 and 5 nmol/nmol P-450/min, respectively.