GM1 Ganglioside Embedded in a Hydrated DOPC Membrane: A Molecular Dynamics Simulation Study

Abstract

A long molecular dynamic simulation of a fully hydrated DOPC bilayer, containing one GM1 ganglioside molecule embedded in each of the two leaflets, has been performed. The location and conformation of the GM1 molecules as well as their effect on the properties of the membrane are investigated in detail. The simulation results reveal that the GM1 molecules are present in two equilibrium arrangements, differing in the orientation of one of their two headgroup branches. The existence of these two equilibrium arrangements of GM1 in the membrane is clearly demonstrated, although their relative population, and hence their free energy difference, cannot be inferred from the present results. A condensing effect on the membrane due to the presence of the GM1 molecules is observed, and the local changes in surface density are analyzed using Voronoi polygons. Although the DOPC molecules are packed more closely in proximity of the gangliosides, the analysis of the deuterium order parameter shows that the DOPC tails are less ordered when close to a GM1.