[Effect of products of radiation-induced free radical fragmentation of phospholipids and temperature on lipid membranes].

Thermotropic behavior of liposomes exposed to gamma-radiation was studied by differential scanning microcalorimetry. It was found that the peak corresponding to the gel-liquid crystal transition for liposomes composed of bovine brain sphingomyelin and dipalmitoyl phosphatidylglycerol broadened and shifted toward the high-temperature region. No effect of irradiation on dipalmitoyl phosphatidylcholine liposomes was observed. Previously it was shown that, on exposure to gamma-rays, sphingomyelin and phosphatidylglycerol, as opposed to phosphatidylcholine, broke down into fragments of lower molecular weight. It is concluded that the accumulation of products of phospholipid fragmentation in the membrane results in the changes of phase transition parameters.