[Participation of oxygen activated species in enzymatic lipid peroxidation in biomembranes]

The participation of oxygen activated species in the induction of lipid peroxidation (LPO) in the membrane systems containing cytochrome P-450 (liver microsomes) and in the membrane fragments devoid of this hemoprotein (brain and skeletal muscle microsomes) was studied. It was shown that the rate of NADH-dependent LPO does not depend on the presence of hemoproteins and the activity of NADH-specific flavoprotein in the membranes. On the other hand, the microsomal membranes of the liver with high specific contents of b5 and P-450 cytochromes and NADPH-specific flavoprotein, had the highest rates of NADPH-dependent LPO. It was found that the most effective inhibitors of free oxygen activated species in the case of NADPH- and NADH-dependent LPO in the microsomal fractions of liver, brain and skeletal muscles are the superoxide (O ./2) anion radical inhibitors. The singlet oxygen (1O2) quenchers inhibit only NADPH-dependent LPO in the liver, however, in a far lesser degree. The hydroxyl radical (OH) scavengers had no effect on enzymatic LPO in all systems studied.