[Effect of phospholipids on the differential spectra of the binding of microsomal cytochrome P-450 with substrates].

The effects of the phospholipid composition of rat liver microsomes on the differential binding spectra of cytochrome P-450 with type I and II substrates (hexobarbital and aniline) were studied. Lysophosphatidylcholine was found to decrease the binding of both type substrates. These changes were reversible, and the spectra were restored by exchanging the microsomal lysophosphatidylcholine for unsaturated phosphatidylcholines, but not with dipalmitoylglycerophosphocholine, sphingomyelin, phosphatidylserine, and phosphatidylethanolamine. Phosphatidylinositol favoured only the binding of type II substrates. The data obtained indicate that the substrate binding capacity of cytochrome P-450 depends specifically on the "boundary" lipids, but not on the bulk lipids of the microsomal membrane.