Small scale membrane mechanics.
Small scale membrane mechanics.
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小尺度膜力学。
DOI：
10.1007/s10237-013-0528-6
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发表时间：
2014
影响因子：
3.5
通讯作者：
Oster,George
中科院分区：
文献类型：
--
作者：
Rangamani,Padmini;Benjamini,Ayelet;Agrawal,Ashutosh;Smit,Berend;Steigmann,DavidJ;Oster,George
helrich模型很好地代表了脂质双分子层形状的大规模变化。然而，有膜过程发生在较小的长度尺度，这一模型无法解决。在这项工作中，我们提出了一个一维连续体模型，在脂质本身的长度尺度上捕捉脂质双层膜的力学。该模型是使用具有脂质取向或“倾斜”作为基本自由度的表面的Cosserat理论开发的。Helfrich模型可以作为曲率很小且脂质倾斜处处为零的特殊情况恢复。我们使用倾斜模型来研究响应蛋白质包涵的局部膜变形。利用耗散粒子动力学（DPD）从粗粒度分子模型中获得参数估计和边界条件，以捕获相同的现象。连续体模型能够再现DPD模型中所见的膜弯曲、拉伸和脂质倾斜。在距离蛋白包合物5-6 nm范围内，脂质倾斜角度松弛为体倾斜角度。重要的是，对于由蛋白质引起的大倾斜梯度，倾斜能量的贡献大于弯曲能量的贡献。因此，倾斜的连续体模型准确地捕获了比膜厚度短的长度尺度上的行为。
Large scale changes to lipid bilayer shapes are well represented by the Helfrich model. However, there are membrane processes that take place at smaller length scales that this model cannot address. In this work, we present a one-dimensional continuum model that captures the mechanics of the lipid bilayer membrane at the length scale of the lipids themselves. The model is developed using the Cosserat theory of surfaces with lipid orientation, or ‘tilt’, as the fundamental degree of freedom. The Helfrich model can be recovered as a special case when the curvatures are small and the lipid tilt is everywhere zero. We use the tilt model to study local membrane deformations in response to a protein inclusion. Parameter estimates and boundary conditions are obtained from a coarse-grained molecular model using dissipative particle dynamics (DPD) to capture the same phenomenon. The continuum model is able to reproduce the membrane bending, stretch and lipid tilt as seen in the DPD model. The lipid tilt angle relaxes to the bulk tilt angle within 5–6 nm from the protein inclusion. Importantly, for large tilt gradients induced by the proteins, the tilt energy contribution is larger than the bending energy contribution. Thus, the continuum model of tilt accurately captures behaviors at length scales shorter than the membrane thickness.