Hill Reghan J, Wang Chih-Ying
Department of Chemical Engineering , McGill University , Montreal, Quebec, H3A 0C5, Canada.
Proc Math Phys Eng Sci. 2014 Jul 8;470(2167):20130843. doi: 10.1098/rspa.2013.0843.
A variety of observations-sometimes controversial-have been made in recent decades when attempting to elucidate the roles of interfacial slip on tracer diffusion in phospholipid membranes. Evans-Sackmann theory (1988) has furnished membrane viscosities and lubrication-film thicknesses for supported membranes from experimentally measured lateral diffusion coefficients. Similar to the Saffman and Delbrück model, which is the well-known counterpart for freely supported membranes, the bilayer is modelled as a single two-dimensional fluid. However, the Evans-Sackman model cannot interpret the mobilities of monotopic tracers, such as individual lipids or rigidly bound lipid assemblies; neither does it account for tracer-leaflet and inter-leaflet slip. To address these limitations, we solve the model of Wang and Hill, in which two leaflets of a bilayer membrane, a circular tracer and supports are coupled by interfacial friction, using phenomenological friction/slip coefficients. This furnishes an exact solution that can be readily adopted to interpret the mobilities of a variety of mosaic elements-including lipids, integral monotopic and polytopic proteins, and lipid rafts-in supported bilayer membranes.
近几十年来，在试图阐明界面滑移对磷脂膜中示踪剂扩散的作用时，人们进行了各种观察，这些观察有时存在争议。埃文斯 - 萨克曼理论（1988年）根据实验测量的横向扩散系数，得出了支撑膜的膜粘度和润滑膜厚度。与自由支撑膜的著名对应模型萨夫曼和德尔布吕克模型类似，双层膜被建模为单一的二维流体。然而，埃文斯 - 萨克曼模型无法解释单拓扑示踪剂的迁移率，如单个脂质或刚性结合的脂质聚集体；它也没有考虑示踪剂 - 叶层和叶层间的滑移。为了解决这些局限性，我们求解了王和希尔的模型，其中双层膜的两个叶层、一个圆形示踪剂和支撑物通过界面摩擦耦合，使用现象学摩擦/滑移系数。这提供了一个精确的解决方案，可很容易地用于解释支撑双层膜中各种镶嵌元件的迁移率，包括脂质、整合单拓扑和多拓扑蛋白质以及脂筏。
