Treatment of Rat Liver Microsomes with Phospholipase C: Effect on Phospholipids and on Cytochromes P450 and b5

Treatment of rat liver microsomes with phospholipase C (CL weLchii) revealed the following: 1. The polar headgroups of 70°/o of the phospholipids can be removed by treatment of microsomes with phospholipase C. When phospholipids that have been extracted from microsomes are treated with phospholipase C, 900/o can be hydrolyzed, suggesting that certain phospholipids are protected from the enzyme in situ. 2. Neither the native conformations of cytochromes P450 and b5 nor their binding to the microsomal membrane are directly affected by phospholipase C treatment. 3. The diglycerides resulting from the action of phospholipase C can be hydrolyzed by an enzyme in the microsomal membrane to yield free fatty acids which partially denature cytochrome P450. 4. The pattern of this partial denaturation is a further indication of the existence of a number of cytochrome P450 species in the microsomal membrane