Measuring the composition-curvature coupling in binary lipid membranes by computer simulations

Abstract

The coupling between local composition fluctuations in binary lipid membranes and curvatureaffects the lateral membrane structure. We propose an efficient method to compute the composition-curvature coupling in molecular simulations and apply it to two coarse-grained membrane models—aminimal, implicit-solvent model and the MARTINI model. Both the weak-curvature behavior that istypical for thermal fluctuations of planar bilayer membranes as well as the strong-curvature regimecorresponding to narrow cylindrical membrane tubes are studied by molecular dynamics simulation.The simulation results are analyzed by using a phenomenological model of the thermodynamics ofcurved, mixed bilayer membranes that accounts for the change of the monolayer area upon bending.Additionally the role of thermodynamic characteristics such as the incompatibility between thetwo lipid species and asymmetry of composition are investigated.