Microscopic Description of the Thermodynamics of a Lipid Membrane at a Liquid-Gel Phase Transition
Microscopic Description of the Thermodynamics of a Lipid Membrane at a Liquid-Gel Phase Transition
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DOI：
10.1134/s0021364018110036
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发表时间：
2018-06-01
期刊：
影响因子：
1.3
通讯作者：
Mukhin, S.
中科院分区：
文献类型：
--
作者：
Kheyfets, B.;Galimzyanov, T.;Mukhin, S.
脂质膜的微观模型的构建，提供了一阶液体-凝胶相变的物理机制的分析易处理的描述。我们证明了液-胶相变是三种主要相互作用的协同作用：脂间的货车范德华吸引力、空间位阻排斥力和疏水张力。该模型明确表明，温度依赖性的脂质间的空间排斥开关系统从液体到凝胶相时，温度降低。这种转换本身表现为随着温度降低脂质的侧向可压缩性增加，使得具有较小面积的相在转变温度以下更优选。该模型给出了定性正确的图片突变的转变温度下的面积每脂质，膜厚度和体积每烃基的脂质链。计算的相变温度对脂链长度的依赖性与实验数据定量一致。脂质分子之间的空间排斥被证明是相变的唯一驱动力，因为货车德瓦尔斯吸引力和疏水张力是弱温度依赖性的。
A microscopic model of the lipid membrane is constructed that provides analytically tractable description of the physical mechanism of the first order liquid-gel phase transition. We demonstrate that liquid-gel phase transition is cooperative effect of the three major interactions: inter-lipid van der Waals attraction, steric repulsion and hydrophobic tension. The model explicitly shows that temperature-dependent inter-lipid steric repulsion switches the system from liquid to gel phase when the temperature decreases. The switching manifests itself in the increase in lateral compressibility of the lipids as the temperature decreases, making phase with smaller area more preferable below the transition temperature. The model gives qualitatively correct picture of abrupt change at transition temperature of the area per lipid, membrane thickness and volume per hydrocarbon group in the lipid chains. The calculated dependence of phase transition temperature on lipid chain length is in quantitative agreement with experimental data. Steric repulsion between the lipid molecules is shown to be the only driver of the phase transition, as van der Waals attraction and hydrophobic tension are weakly temperature dependent.