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arXiv 1607.06167cond-mat.softphysics.bio-ph
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二元荷电脂膜的粗粒分子动力学模拟:相分离和形态动力学

Coarse-grained molecular dynamics simulation of binary charged lipid membranes: Phase separation and morphological dynamics

Hiroaki Ito, Yuji Higuchi, Naofumi Shimokawa

摘要:

生物膜主要由中性和带电的脂质组成,具有多种功能结构和动力学。在这里,我们报告了一个粗粒度的分子动力学(MD)模拟的相分离和形态动力学在带电的脂质双层囊泡。与中性囊泡相比,带电囊泡中电荷头基之间的屏蔽长程静电斥力延迟或抑制了侧向相分离,表明相分离机制从旋节分解转变为成核或均匀分散。此外,静电斥力导致形态学的变化,如孔的形成,并进一步转化为磁盘,字符串,和bicelle结构,这是时空耦合到带电脂质的横向隔离。基于我们的粗粒度MD模拟,我们提出了一个合理的机制,在分子水平上的孔形成。在一个带电的脂质丰富的域中的孔的形成是由在域中的局部分子取向的先前的干扰。

英文摘要:

Biomembranes, which are mainly composed of neutral and charged lipids, exhibit a large variety of functional structures and dynamics. Here, we report a coarse-grained molecular dynamics (MD) simulation of the phase separation and morphological dynamics in charged lipid bilayer vesicles. The screened long-range electrostatic repulsion among charged head groups delays or inhibits the lateral phase separation in charged vesicles compared with neutral vesicles, suggesting the transition of the phase-separation mechanism from spinodal decomposition to nucleation or homogeneous dispersion. Moreover, the electrostatic repulsion causes morphological changes, such as pore formation, and further transformations into disk, string, and bicelle structures, which are spatiotemporally coupled to the lateral segregation of charged lipids. Based on our coarse-grained MD simulation, we propose a plausible mechanism of pore formation at the molecular level. The pore formation in a charged-lipid-rich domain is initiated by the prior disturbance of the local molecular orientation in the domain.

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