Molecular dynamics simulations of octyl glucoside micelles: Dynamic properties
Molecular dynamics simulations of octyl glucoside micelles: Dynamic properties
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DOI：
10.1021/jp004475o
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发表时间：
2001-09-06
影响因子：
3.3
通讯作者：
Pastor, RW
中科院分区：
文献类型：
--
作者：
Bogusz, S;Venable, RM;Pastor, RW
使用分子动力学模拟探索了辛基葡萄糖苷 (OG) 胶束的动态特性。研究的系统包括含有 10、20、27、34、50 和 75 种脂质的单个 β-OG 胶束；两个 20 脂质 P-OG 胶束； 27β-OG和四个葡萄糖分子的分散溶液。计算得出的胶束聚集数在 34 到 75 之间的尾碳的 C-13 NMR T-1 弛豫时间与实验吻合良好；这些结果与基于平移扩散的胶束尺寸估计一致。然而，与溶剂强烈偶联的头基碳的 TI 太大。这主要是由于 TIP3P 水模型的粘度低，随后弛豫时间的缩放导致与葡萄糖环中的碳的实验一致，但与环外碳的实验不一致；后一个差异的可能原因是扭转势垒稍高。对胶束动力学的详细分析揭示了形状变化的时间尺度为数十至数百皮秒，而胶束内的旋转和脂质扩散发生在纳秒内。 NMR Ti 弛豫的主要组成部分是脂质摆动和链异构化，以及形状变化时间尺度上较慢的协同运动。脂质横向扩散和整体胶束。翻滚对 NMR 弛豫没有显着贡献。还演示了纳秒时间尺度的胶束自组装。两个 20 个脂质胶束合并，27 个分散的脂质聚集，突出了分子动力学模拟可实现的一系列新行为。
Dynamic properties of octyl glucoside (OG) micelles were explored using molecular dynamics simulations. Systems studied included individual beta -OG micelles containing 10, 20, 27, 34, 50, and 75 lipids; two 20 lipid P-OG micelles; a disperse solution of 27 beta -OG, and four molecules of glucose. Calculated C-13 NMR T-1 relaxation times for the tail carbons of micelle aggregation numbers between 34 and 75 agreed well with experiment; these results are consistent with estimates of the micelle size based on translational diffusion. However, TI's for the head-roup carbons, which couple strongly with the solvent, were too large. This was primarily due to the low viscosity of the TIP3P water model, and subsequent scaling of the relaxation times led to agreement with experiment for the carbons in the glucose ring, but not the exocyclic carbon; the likely reason for the latter discrepancy is a torsional potential barrier that is slightly too high. A detailed analysis of the micelle dynamics revealed shape changes on the time scale of tens to hundreds of picoseconds, while rotation and lipid diffusion within the micelle occur over nanoseconds. The primary components of NMR Ti relaxation are lipid wobble and chain isomerization, as well as slower concerted motions on the time scale of the shape changes. Lipid lateral diffusion and overall micelle. tumbling do not contribute significantly to NMR relaxation. Micelle self-assembly on the nanosecond time scale was also demonstrated. The two 20 lipid micelles merged and the 27 dispersed lipids aggregated, highlighting a new range of behavior accessible to molecular dynamics simulation.