Coarse-Grained Model for Phospholipid/Cholesterol Bilayer

TL;DR

This paper introduces a new coarse-grained model for DPPC/cholesterol bilayers that enables large-scale membrane simulations with high efficiency, accurately capturing phase behavior and domain formation.

Contribution

The authors develop a systematic coarse-grained model derived from atomistic simulations, significantly improving simulation efficiency while maintaining key membrane properties.

Findings

Model achieves ~10^8 times speed-up over atomistic simulations.

Results support formation of cholesterol-rich and cholesterol-poor domains.

Model accurately reproduces experimental phase behavior.

Abstract

We construct a coarse-grained (CG) model for dipalmitoylphosphatidylcholine (DPPC)/cholesterol bilayers and apply it to large-scale simulation studies of lipid membranes. Our CG model is a two-dimensional representation of the membrane, where the individual lipid and sterol molecules are described by point-like particles. The effective intermolecular interactions used in the model are systematically derived from detailed atomic-scale molecular dynamics simulations using the Inverse Monte Carlo technique, which guarantees that the radial distribution properties of the CG model are consistent with those given by the corresponding atomistic system. We find that the coarse-grained model for the DPPC/cholesterol bilayer is substantially more efficient than atomistic models, providing a speed-up of approximately eight orders of magnitude. The results are in favor of formation of cholesterol-rich and cholesterol-poor domains at intermediate cholesterol concentrations, in agreement with the experimental phase diagram of the system. We also explore the limits of the novel coarse-grained model, and discuss the general validity and applicability of the present approach.