[Lysophospholipase activity in mitochondrial membranes of the rat liver]

Changes in the amount of phospholipids and lysophospholipids of mitochondria and their fragments have been studied under long-term heat incubation. A discrepancy is found between a decrease in the content of phospholipids as a result of their hydrolysis by mitochondrial phospholipase A2 and accumulation of the corresponding lysoderivatives. Data are presented which show that all this is a result of lysoderivatives splitting by lysophospholipase A. The activity of this enzyme is observed in incubation of intact mitochondria, their "ghosts" as well as fractions of the external and internal mitochondrial membranes. It is shown that lysophospholipase A is able to hydrolyze both endogenic and exogenic substrates. The enzyme is active at pH 6.0, lysocardiolipin being the most preferable substrate.