Effect of Na+ and Ca2+ Ions on a Lipid Langmuir Monolayer: An Atomistic Description by Molecular Dynamics Simulations
Effect of Na+ and Ca2+ Ions on a Lipid Langmuir Monolayer: An Atomistic Description by Molecular Dynamics Simulations
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DOI：
10.1002/cphc.200800321
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发表时间：
2008-12-01
期刊：
影响因子：
2.9
通讯作者：
Cascales, Jose Javier Lopez
中科院分区：
文献类型：
--
作者：
Casares, Juan Jose Giner;Camacho, Luis;Cascales, Jose Javier Lopez
从生物物理学和纳米技术的角度来看，研究碱金属和碱土金属阳离子对朗缪尔单分子层的影响是相关的。在这项工作中，通过分子动力学模拟研究了 Na+ 和 Ca2+ 对二肉豆蔻酰磷脂 (DMPA) 阴离子 Langmuir 脂质单层模型的影响。根据静电相互作用分析阳离子类型对脂质结构、脂质-脂质相互作用和脂质排序的影响。发现对于固相的脂质单层，阳离子对脂质单层性质的影响可以忽略不计。阳离子对气相脂质单层的影响增强，其中钠离子与钙离子相比表现出高度脱水。这种水合壳的损失部分地通过脂质-离子-脂质桥的形成得到补偿。这种差异归因于 Ca2+ 的电荷半径比 q/r 较高，与 Na+ 相比，这使得离子脱水不太有利。由于钠离子和钙离子的脱水行为不同，与 Na+ 相比，Ca2+ 的脂质-脂质协调、脂质-离子协调和脂质有序性减弱。此外，对于脂质朗缪尔单层的气相和固相，研究了脂质构象和跨脂质/水界面的离子脱水。
Studying the effect of alkali and alkaline earth metal cations on Langmuir monolayers is relevant from biophysical and nanotechnological points of view. In this work, the effect of Na+ and Ca2+ on a model of an anionic Langmuir lipid monolayer of dimyristoylphosphatidate (DMPA) is studied by molecular dynamics simulations. The influence of the type of cation on lipid structure, lipid-lipid interactions, and lipid ordering is analyzed in terms of electrostatic interactions. It is found that for a lipid monolayer in its solid phase the effect of the cations on the properties of the lipid monolayer can be neglected. The influence of the cations is enhanced for the lipid monolayer in its gas phase, where sodium ions show a high degree of dehydration compared with calcium ions. This loss of hydration shell is partly compensated by the formation of lipid-ion-lipid bridges. This difference is ascribed to the higher charge-to-radius ratio q/r for Ca2+, which makes ion dehydration less favorable compared to Na+. Owing to the different dehydration behavior of sodium and calcium ions, diminished lipid-lipid coordination, lipid-ion coordination, and lipid ordering are observed for Ca2+ compared to Na+. Furthermore, for both gas and solid phases of the lipid Langmuir monolayers, lipid conformation and ion dehydration across the lipid/water interface are studied.