DIFFERENTIAL SCANNING CALORIMETRIC STUDY OF MIXTURES OF CHOLESTEROL WITH PHOSPHATIDYLSERINE OR GALACTOCEREBROSIDE

The thermotropic behavior of mixtures of cholesterol with phosphatidylserine (PS) or galactocerebroside was investigated. In PS/cholesterol mixtures at low cholesterol concentrations only 1 peak in the thermograms is obtained. At .apprx. Xchol = 0.3 another peak at higher temperatures is also seen, this peak stems from phase transition of almost pure cholesterol phase. However, increase of Xchol results in further incorporation of cholesterol into the mixture. In galactocerebroside-cholesterol mixtures of > Xchol 0.4, at least 2 domains differing in cholesterol content and thermotropic properties coexist. In the presence of cholesterol even at 1:1 molar ratios the phosphatidylserine or galactocerebroside are still undergoing melting.