Molecular dynamics study of lipid bilayer asymmetry induced by ion concentration gradient and electronic polarizability

Abstract

ABSTRACT It has been difficult to reproduce an arbitrary value of a membrane potential in molecular dynamics (MD) simulations for lipid bilayer systems because the membrane potential is sensitively affected by the net charge difference. The membrane potential and membrane properties depend on the intra- and extracellular ion concentrations. In this paper, we present a simple procedure to reproduce an arbitrary value of the membrane potential by all-atom MD simulations for two POPC bilayers system. The calculated membrane capacitance is consistent with an experimental result for the POPC. We show a correlation between the ion imbalance and the number of lipid molecules per leaflet to reproduce an arbitrary value of the membrane potential in MD simulations. Moreover, we show an asymmetry of lipid head group induced by the electronic polarizability and an asymmetry of lipid tail and water molecules on the membrane surface induced by the ion concentration gradient.