Non-polar interactions between cholesterol and phospholipids: a molecular dynamics simulation study

Abstract

A 15-ns molecular dynamics simulation of the fully hydrated dimyristoylphosphatidylcholine-cholesterol (DMPC-Chol) bilayer containing ∼22 mol% Chol was carried out. An 8-ns trajectory was analysed to investigate the effect of Chol on the chain packing in the bilayer core. While the packing of DMPC chains on the smooth α-face side of the Chol ring is similar to that in the pure DMPC bilayer, the packing on the rough β-face side is less regular and less tight. Two methyl groups located on the Chol β-face disturb the packing; in effect, van der Waals (vdW) interactions between Chol rings and DMPC chains are weaker than the ones between sole DMPC chains. VdW interactions between an alkyl chain of DMPC and an isooctyl tail of Chol are similarly strong as those between two DMPC chains.