Study of Lipid Heterogeneity on Bilayer Membranes Using Molecular Dynamics Simulations

Human cell membranes consist of various lipids that are essential for their structure and function. Several experimental techniques have been used to characterize the composition of human cell membranes; however, it is challenging task to depict in theoretical calculations. In this work, we have investigated the structure-function relationship of lipids in both homogeneous and heterogeneous bilayer models using Molecular-Dynamics to delineate the effect of heterogeneity on the biophysical properties of membranes. Results illustrated that the biophysical properties of heterogeneous membranes are dependent on the lipid composition and concentration. We observed that the presence of cholesterol in combination with other lipids, introduced compactness of the membrane, increasing the membrane thickness. The density of lipid head group, phosphate, and glycerol-ester in presence of cholesterol with or without sphingomyelin is an underlying reason for membrane ordering. The radial distribution function shows that the cholesterol, sphingomyelin and phosphatidylethanolamine self-interaction and the interaction between cholesterol and phosphatidylethanolamine determine the structure and function of the heterogeneous membrane. Our findings provide a baseline for membrane heterogeneity that would help in understanding the physiological properties of membranes and may help to wisely select the heterogeneous bilayer model to mimic the realistic human cell membranes and the associated phenomenon.