Balance of Solvent and Chain Interactions Determines the Local Stress State of Simulated Membranes
Balance of Solvent and Chain Interactions Determines the Local Stress State of Simulated Membranes
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溶剂和链相互作用的平衡决定模拟膜的局部应力状态
DOI：
10.1021/acs.jpcb.0c03937
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Vanegas, Juan M.
中科院分区：
文献类型：
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作者：
Winkeljohn, Conner M.;Himberg, Benjamin;Vanegas, Juan M.
模型脂膜的内部机械状态的表征对于理解生物功能的微观基础是必不可少的，例如在弹性理论如Helfrich框架的背景下的膜分裂和细胞器成形。在这里，我们计算横向应力或压力分布的脂质双层和水真空界面的分子动力学模拟，以了解溶剂处理和力场参数化膜的局部机械特征上发挥的作用。我们重点关注两个原子模型：GROMOS 43 A1-S3和CHARMM 36，以及MARTINI粗粒力场的几种变体，包括单珠非极性水、三点可极化水、大多极水和无溶剂变体。我们的研究结果表明，由于烃-水界面处溶剂-溶剂和溶剂-溶质力的平衡以及成对的根本不同处理（例如，货车德瓦耳斯、库仑等）和多体相互作用（角度和扭转）。的双层应力分布的二阶矩的数值积分表明，不同的本地分布的排斥和吸引力的应力在整个膜，由于不同的力场参数化，可能会导致在宏观弹性性能的大幅变化。
Characterization of the internal mechanical state of model lipid membranes is essential to understand the microscopic underpinnings of biological functions such as membrane fission and organelle shaping within the context of elastic theories such as the Helfrich framework. Here, we compute lateral stress or pressure profiles from molecular dynamics simulations of lipid bilayers and water–vacuum interfaces to understand the role that solvent treatment and force-field parametrization plays on the local mechanical features of membranes. We focus on two atomistic models, GROMOS 43A1-S3 and CHARMM36, and several variants of the MARTINI coarse-grained force-field, including the single-bead nonpolar water, three-point polarizable water, big multipole water, and solvent-free variants. Our results show that the various atomistic and coarse-grained force-fields produce contrasting lateral stress profiles as a result of the balance of solvent–solvent and solvent–solute forces at the hydrocarbon–water interface and fundamentally different treatment of pairwise (e.g., van der Waals, Coulomb, etc.) and multibody interactions (angles and torsions). Numerical integration of the second moment of the bilayer stress profiles indicates that different local distributions of repulsive and attractive stresses across the membrane, due to distinct force-field parametrizations, may result in substantial variations in macroscopic elastic properties.