Composition of lipids bound to pure cytochrome P-450 of cholesterol side-chain cleavage enzyme from bovine adrenocortical mitochondria.

Phospholipids bound to highly purified cytochrome P-450 from bovine adrenocortical mitochondria, part of the enzyme complex responsible for catalyzing the conversion of cholesterol to pregnenolone, have been examined for comparison with the bulk phospholipids of the mitochondria from the same tissue. In both cases, the major phospholipids are phosphatidylcholine (PC) (37%) and phosphatidylethanolamine (PE) (56%), as well as smaller amounts of sphingomyelin and diphosphatidylglycerol. The fatty acid compositions of the four classes of phospholipids and of the neutral lipids bound to the pure enzyme are indistinguishable from those of the respective mitochondrial lipids. They are also similar to those of mitochondria from other organs except for high levels of arachidonate and low levels of diphosphatidylglycerol.