Boundary Conditions on Conical Hydrophobic Inclusions in Lipid Membranes

Abstract

Using all-atom Molecular Dynamics simulations including explicit water, we consider hydrophobic inclusions of conical shape that are inserted into phospholipid bilayer membranes with the goal to determine the boundary conditions at the inclusion-membrane interface. We determine the mean membrane shape around the inclusion and from that extract the membrane vertical-displacement, thickness and bending-angle pro�les as possible order parameters in a coarse-grained description of the membrane shape. Via comparison with solutions of membrane-shape equations obtained by Landau theory, we investigate the appropriate boundary condition at the inclusion-membrane interface. We �nd that in the considered cone opening angle range, the boundary values of the di�erent order parameters that describe the membrane deformation are rather constant, which re ects an inherently preferred shape of membranes at conical inclusions.