[Lipid dependence of mitochondrial monoamine oxidase from rat hepatoma 27 with the use of rat liver lipid exchange proteins].

The ability of liver lipid exchange proteins to introduce foreign phospholipids into intact mitochondria was used for a study of the lipid dependence of monoamine oxidase. Introduction of exogenous phosphatidylcholine into rat hepatoma mitochondria, in which both the monoamine oxidase activity and the phosphatidylcholine content are comparatively low, leads to considerable activation of the enzyme. The introduction of exogeneous phosphatidylserine, phosphatidylethanolamine and cardiolipin has no activating effect. This indicates that the decreased activity of monoamine oxidase in the hepatoma may be due to a low amount of phosphatidylcholine. The method described allows the study in situ of the lipid dependence of non-solubilized membrane-bound enzymes.