Department of Chemistry and Research Institute for Basic Science, Sogang University, Seoul 121-742, Republic of Korea.
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Phys Rev E. 2016 Jan;93(1):012409. doi: 10.1103/PhysRevE.93.012409. Epub 2016 Jan 19.
Lipid bilayers are a model system for studying the properties of cell membranes. For lipid bilayers of a single lipid component, there is a phase transition from a fluid phase to a gel phase as the temperature is decreased. The dynamic behavior of lipids in the gel phase is interesting: some models show dynamic heterogeneity with a large disparity in timescales between fast and slow molecules, and a spatial segregation of the slow molecules. In this paper we study the dynamics of coarse-grained models of lipid bilayers using the dry Martini, Lennard-Jones Martini, polarizable Martini, and BMW models. All four models show similar dynamical behaviors in the gel phase although the transition temperature is model-dependent. We find that the primary mode of transport in the gel phase is a hopping of the lipid molecules. Hopping is seen in both the translational and rotational dynamics, which are correlated, i.e., the lipid molecules display a swing-like motion in the gel phase.
脂质双层是研究细胞膜性质的模型系统。对于单一脂质成分的脂质双层，随着温度的降低，会发生从流体相到凝胶相的相变。凝胶相中脂质的动态行为很有趣：一些模型显示出动态异质性，快速分子和慢速分子之间的时间尺度差异很大，并且慢速分子存在空间隔离。在本文中，我们使用干马蒂尼、伦纳德-琼斯马蒂尼、可极化马蒂尼和宝马模型研究了脂质双层的粗粒模型的动力学。尽管转变温度取决于模型，但所有四个模型在凝胶相中都表现出相似的动力学行为。我们发现，在凝胶相中，脂质分子的主要输运模式是跳跃。在平移和旋转动力学中都可以看到跳跃，它们是相关的，即脂质分子在凝胶相中显示出摆动运动。
