[Role of structural factor in the kinetics of free-radical oxidation of lipids in the membranes].

Kinetics of free radical oxidation of lipids (formation of primary molecular products - hydroperoxides, secondary products - carbonyl substances and "fluorescent pigments") was studied in various membrane fragments, which were distinctly differentiated by their fatty acid composition. The non-enzymatic catalysis of lipoperoxidation in these systems was initiated by addition of Fe2+ + ascorbic acid. The membrane fragments were isolated from microsomes and mitochondria of rat liver tissue, external segments of frog retina rods, sarcoplasmic reticulum of rabbit and carp skeletal muscles and from microsomes of rabbit brain. In membrane structures the free radical oxidation of lipids developed following the same pattern as the liquid-phase oxidation of alkenes. But in phospholipids of biomembranes the rate of hydroperoxides formation did not correlate with the level of unsaturation of their polyene acyls. The rate of peroxidation of unsaturated fatty acids was distinctly determined by their structural organization in membranes.