EFFECT OF TEMPERATURE ON THE DISTRIBUTION OF PYRENE IN PHOSPHATIDYLCHOLINE LIPOSOMES

Pyrene fluorescence was studied in soybean phosphatidylcholine liposom es at 20-60-degrees-C - above the temperature of the main phase transi tion. Abnormal temperature curves were observed for the fluorescence p arameters reflecting the probe microenvironment properties. Pyrene acc ess for aqueous quencher potassium iodide varies in this temperature r ange. The effects are suggested to arise from heterogeneity of the pro be intramembrane distribution which is more pronounced at higher tempe ratures, molecular exchange being negligible between the pyrene pools of different membrane locations during the fluorescence lifetime.