Calorimetric properties of mixtures of distearoylphosphatidylcholine and sulfatides with definite fatty acid composition.

The thermotropic behavior of multilamellar liposomes prepared from mixtures of distearoyllecithin and sulfatide of definite fatty acid composition, has been studied by DTA calorimetry. The saturated stearoyl- and lignoceroyl-sulfatides do not modify significatively both the delta H and the Tm of the phase transition of the lecithins. These parameters, on the contrary, are decreased by all the sulfatides containing unsaturated fatty acids. A contrasting effect is at last exhibited by alpha-OH-stearoylsulfatide which promotes a decrease in delta H but not in Tm of the phase transition. The possibility that these sulfatide properties can influence the dynamic interactions and the sovramolecular organization of the phospholipid bilayers has been discussed.