Cholesterol-induced alterations of the packing properties of gangliosides: an EPR study

The effect of cholesterol (Chol) on two kinds of glycolipid assemblies, one composed of monosialogangliosides (G(M1a)) and the other formed by a natural mixture of bovine brain gangliosides (TBG), has been analysed. The experimental approach involves spin label electron paramagnetic resonance (EPR) in aqueous lipid dispersions. The employment of a hydrosoluble spin label and a `quencher´ of the EPR signal that is not able to permeate lipid interfaces, allowed us to conclude that G(M1a)/Chol mixtures give rise to vesicles at Chol proportions for which TBG/Chol mixtures form micelles. The use of different liposoluble spin labels reveals that cholesterol produces a straightening of the hydrocarbon chains in both lipid systems. In GM1a/Chol mixtures, this feature is more pronounced and it is coupled with a decrease in polarity at the chain ends.Fil: Pincelli, Michelina Marta. Universidad Nacional de Córdoba; ArgentinaFil: Levstein, Patricia Rebeca. Universidad Nacional de Córdoba; ArgentinaFil: Fidelio, Gerardo Daniel. Universidad Nacional de Córdoba; ArgentinaFil: Gennaro, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin