AI 中文总结
本研究通过分子动力学模拟和维里应力分析，将脂质膜面积压缩模量分解为分子基团贡献，发现烃链主导弹性，水-头基作用次之，为膜弹性提供微观解释。
AI 中文摘要
面积压缩模量是脂质膜力学性质的关键描述符，但决定这种弹性的分子相互作用并不能仅从总模量中直接看出。本文中，我们结合了由粗粒化Martini 3力场描述的POPC双分子层的分子动力学模拟与维里应力分析，将面积压缩模量分解为来自分子基团及其相互作用的贡献。我们评估了部分横向张力作为膜面积应变的函数，并利用其在平衡态下的导数来获得对面积压缩模量的相应贡献。烃链提供了主要的正贡献，约占总模量的70%，而水-脂质相互作用贡献约30%，主要通过水-头基相互作用实现。在双分子层内部，头基与头基-链贡献的大小相近但符号相反，几乎相互抵消。单层间的直接相互作用仅贡献了双分子层模量的约3%，表明两个单层的弹性响应几乎是可加的。弹性贡献的层级与平衡部分张力的层级显著不同，表明负责静态应力平衡的相互作用不一定决定膜刚度。这种分解为脂质双分子层面积弹性提供了微观解释。
英文摘要
The area compressibility modulus is a key descriptor of lipid membrane mechanics, but the molecular interactions that determine this elasticity are not evident from the total modulus alone. Here, molecular dynamics simulations of a POPC bilayer described by the coarse-grained Martini 3 force field were combined with virial stress analysis to decompose the area compressibility modulus into contributions from molecular groups and their interactions. Partial lateral tensions were evaluated as functions of membrane area strain, and their derivatives at the equilibrium state were used to obtain the corresponding contributions to the area compressibility modulus. Hydrocarbon chains provided the dominant positive contribution, accounting for approximately 70% of the total modulus, whereas water-lipid interactions contributed approximately 30%, predominantly through water-headgroup interactions. Within the bilayer, the headgroup and headgroup-chain contributions were of similar magnitude but opposite in sign and nearly canceled. Direct intermonolayer interactions contributed only about 3% of the bilayer-only modulus, indicating an almost additive elastic response of the two monolayers. The hierarchy of elastic contributions differed markedly from that of equilibrium partial tensions, showing that interactions responsible for static stress balance are not necessarily those governing membrane stiffness. This decomposition provides a microscopic interpretation of lipid bilayer area elasticity.
