Influence of different glycosphingolipids on the conductometric properties of a model phospholipid membrane system

The conductometric properties of aqueous solutions of liposomes built up by inserting different gangliosides at different concentrations in a phospholipid bilayer have been investigated in the radio frequency region, where the alteration of the electrical surface polarization produced in the membrane structure by the ganglioside insertion can be properly observed. We have studied a series of gangliosides (GM1, GM2, GM3, GD1a, GD1b, aGM1) characterized by the same hydrophobic part but with different hydrophilic portions. The results show a quite complex conductivity behaviour that can be only partially accounted for in terms of a surface conductance contribution. Some phenomenological correlations between the hydrophilic head group structure and the electrical conductivity behaviour are presented.