Effect of Lipid Depletion on the Kinetics of Microsomal NADH-Cytochrome c Reductase

Abstract

Removal of lipids from [chicken liver] microsomes with 90% acetone resulted in 50% or more decrease of NADH-cytochrome c reductase activity. The decrease of the enzyme activity was a result of lowering of Vmax and increase in Km. When sufficient amounts of phospholipids such as phosphatidylserine or phosphatidylinositol were added to the acetone-treated microsomes, the reductase activity was restored completely to the original level. When ferricyanide was used in place of cytochrome c as electron acceptor, the rate of reduction of ferricyanide was not affected by the lipid depletion and Vmax and Km for ferricyanide remained unchanged.