Human cell membranes consist of various lipids that are essential for their structure and function. It typically comprises phosphatidylcholine (POPC), phosphatidylethanolamine (POPE), phosphatidylserine (POPS), sphingomyelin (PSM), and cholesterol (CHL). Several experimental and computational techniques have been employed to characterize the composition of human cell membranes, however, CHL enriched membrane is still not clearly understood through these techniques. Molecular dynamics simulation results illustrated the biophysical properties of heterogeneous membranes based on the lipid composition as well as the concentration of lipids, exclusively for CHL and PSM. Herein, we have investigated the structure-function relationships of lipids comparatively to delineate the effect of heterogeneity on the biophysical properties of different membranes. It has been observed that the significant fraction of CHL (i.e., ~33% in ternary, ~25% in quaternary, and ~16% in senary type bilayers) in combination with other lipids introduced compactness, and increased the thickness of the membrane. The analysis of lipid mass density stated that the density of lipid head group, phosphate_, and glycerol-ester in presence of CHL with or without PSM is an underlying reason for membrane ordering. Results also revealed that the presence of POPI and POPS are the reasons for an adequate drop in the ordering of lipid chain, particularly on POPE chain. The self-interaction of CHL, PSM, POPE and the interaction of CHL and POPC with POPE seem to determine the structure and function of the heterogeneous membrane. Our findings provide a qualitative understanding of the effect of membrane heterogeneity on the physiological properties of membranes. The structures inspected in this study would help to select the heterogeneous bilayer model to mimic the human cell membranes to analyse or characterize the membrane-associated phenomena.

人体细胞膜由对其结构和功能必不可少的各种脂质组成。它通常包含磷脂酰胆碱 (POPC)、磷脂酰乙醇胺 (POPE)、磷脂酰丝氨酸 (POPS)、鞘磷脂 (PSM) 和胆固醇 (CHL)。已经采用了几种实验和计算技术来表征人类细胞膜的组成，但是，通过这些技术仍然没有清楚地了解富含 CHL 的膜。分子动力学模拟结果说明了基于脂质成分和脂质浓度的异质膜的生物物理特性，仅适用于 CHL 和 PSM。在此，我们比较研究了脂质的结构-功能关系，以描绘异质性对不同膜生物物理特性的影响。已经观察到显着比例的 CHL（即，三元中的~33%，四元中的~25% 和三元型双层中的~16%）与其他脂质结合引入了致密性，并增加了膜的厚度。脂质质量密度分析表明，脂质头基团、磷酸盐的密度_，和甘油-酯在有或没有PSM CHL的存在对膜排序的潜在原因。结果还表明，POPI 和 POPS 的存在是脂质链排序充分下降的原因，尤其是在 POPE 链上。CHL、PSM、POPE的自相互作用以及CHL和POPC与POPE的相互作用似乎决定了异质膜的结构和功能。我们的发现提供了对膜异质性对膜生理特性影响的定性理解。本研究中检查的结构将有助于选择异质双层模型来模拟人类细胞膜，以分析或表征膜相关现象。