Brewster R, Pincus P A, Safran S A
Weizmann Institute of Science, Department of Materials and Interfaces, Rehovot, Israel.
Biophys J. 2009 Aug 19;97(4):1087-94. doi: 10.1016/j.bpj.2009.05.051.
Cell membranes contain small domains (on the order of nanometers in size, sometimes called rafts) of lipids whose hydrocarbon chains are more ordered than those of the surrounding bulk-phase lipids. Whether these domains are fluctuations, metastable, or thermodynamically stable, is still unclear. Here, we show theoretically how a lipid with one saturated hydrocarbon chain that prefers the ordered environment and one partially unsaturated chain that prefers the less ordered phase, can act as a line-active component. We present a unified model that treats the lipids in both the bulk and at the interface and show how they lower the line tension between domains, eventually driving it to zero at sufficiently large interaction strengths or at sufficiently low temperatures. In this limit, finite-sized domains stabilized by the packing of these hybrid lipids can form as equilibrium structures.
细胞膜包含脂质的小区域（尺寸在纳米量级，有时称为筏），其碳氢链比周围本体相脂质的碳氢链排列更有序。这些区域是波动的、亚稳态的还是热力学稳定的，目前仍不清楚。在这里，我们从理论上表明，一种具有一条偏好有序环境的饱和碳氢链和一条偏好无序相的部分不饱和链的脂质，如何能作为一种线活性成分。我们提出了一个统一模型，该模型处理本体和界面处的脂质，并展示它们如何降低区域之间的线张力，最终在足够大的相互作用强度或足够低的温度下将其驱动至零。在此极限下，由这些混合脂质的堆积稳定的有限尺寸区域可以形成平衡结构。
