Molecular dynamics simulations of gel (LβI) phase lipid bilayers in constant pressure and constant surface area ensembles
Molecular dynamics simulations of gel (LβI) phase lipid bilayers in constant pressure and constant surface area ensembles
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DOI：
10.1063/1.481085
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发表时间：
2000-02
影响因子：
4.4
通讯作者：
R. Venable;B. Brooks;R. Pastor
中科院分区：
文献类型：
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作者：
R. Venable;B. Brooks;R. Pastor
描述了293 K下双棕榈酰磷脂酰胆碱双分子层凝胶状态的一系列分子动力学模拟结果。模拟范围从40ps到2.5 ns，清楚地表明：在平衡过程中，灵活的电池几何形状是必不可少的；埃瓦尔德静电求和法优于球面截止法；与2链羰基的水交换发生在ns时间尺度上，而1链几乎没有水化反应。总体上与实验结果一致（d间距、链倾斜、分数间扭式和面积压缩模量），尽管每个脂质的表面积略有低估。在大约2ns的过程中，链2的扭转1从完全的间扭负（如从相关脂质晶体结构建模的初始条件中指定的）随机化到g+/g−的混合物是该研究的一个关键特征。在恒表面张力条件下，扭转平衡稳定进行，但不稳定。
The results of a series of molecular dynamics simulations of the gel state of a dipalmitoylphosphatidylcholine bilayer at 293 K are described. The simulations, ranging from 40 ps to 2.5 ns, show clearly that: a flexible cell geometry is essential during equilibration; Ewald summation of electrostatics is superior to spherical cutoff methods; water exchange with the carbonyl group of chain 2 takes place on the ns time scale, while there is almost no hydration of chain 1. There is overall good agreement (D-spacing, chain tilt, fraction gauche, and area compressibility modulus) with experiment, though the surface area per lipid is slightly underestimated. The randomization of torsion 1 of chain 2 from exclusively gauche minus (as specified in the initial condition modeled from the crystal structure of a related lipid) to a mixture of g+/g− over the course of approximately 2 ns is a critical feature of the study. The torsional equilibration proceeded steadily when simulating at constant surface tension, but w...