Collective phenomena in confined micellar systems of gangliosides

In the present paper, we investigate in deeper detail some features of the bistable behavior observed in micellar aggregates of gangliosides. In these systems, a collective transition takes place connected to different possible conformations of the glycosidic headgroup and resulting in different aggregation numbers for different thermal hystories. Light scattering experiments per-formed on mixed micelles indicate that it is the aggregated structure which dictates the conformation a ganglioside monomer assumes, among the allowed ones. Moreover, density measurements confirm the results previously obtained by DSC and show that the conformation of the hydrophobic tails at a given temperature is coupled to that of the headgroup. NMR measurements are consistent with previous results and, on a more local scale, indicate that the hydration of the ganglioside molecule is affected by the conformational transition. (C) 2002 Elsevier Science B.V. All rights reserved.