MEMBRANE CROSSING BY A POLAR MOLECULE - A MOLECULAR-DYNAMICS SIMULATION

This paper is concerned with the permeability of a glycerolipid bilayer to a polar molecule. We have simulated by molecular dynamics the interaction between a molecule of dimethyl sulfoxide (DMSO) and a membrane of glycerol monoleate in solution. We find that the structure of the membrane is affected only locally by the crossing of the polar molecule. The DMSO molecule opens a hole at the surface of the bilayer which allows a water molecule to penetrate inside. This water is then expelled as the DMSO penetrates more deeply inside. Finally we find that the energetics of crossing is affected by structural transformations occuring on a timescale of 20 ps and over.