RADIOFREQUENCY DIELECTRIC-SPECTROSCOPY OF SYNTHETIC BILAYERS CONTAINING GLYCOLIPIDS

The electrical conductivity,of aqueous solutions of colloidal phosphol ipid-ganglioside mixtures has been measured in the frequency range fro m 10 kHz to 100 MHz, where a conductivity dispersion due to the interf acial polarization occurs. Insertion of GM1 ganglioside in the phospho lipid bilayer alters markedly the electrical behaviour of the whole su spension that exhibits some interesting features, which depend on the GM1 concentration. In a restricted range of the ganglioside concentrat ion, the experimental data can be partially explained by introducing a surface conductivity contribution in the usual conductivity theory of heterogeneous systems. Although preliminary, these measurements indic ate that gangliosides, according to the structural shape they assume, modify the electrical properties of the lipid bilayer. This effect may be relevant to understanding ganglioside interactions with lipid comp onents of biological cell membranes.