Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
J Chem Theory Comput. 2020 Nov 10;16(11):7195-7206. doi: 10.1021/acs.jctc.0c00862. Epub 2020 Oct 30.
We present a version of the coarse-grained Cooke lipid model, modified to simulate asymmetric lipid membranes. It is inspired by a method employed by Wang et al. [ 2013, 13, 1093-1106] for artificially penalizing lipid flip-flop but copes more robustly with differential stress, at the cost of one additional bead per lipid and the concomitant increase in computational overhead. Bilayer asymmetry ultimately breaks down beyond a system size dependent critical differential stress, which can be predicted from a simple analytical model. We remeasure many important material parameters for the new model and find it to be consistent with typical fluid lipid membranes. Maintaining a stable stress asymmetry has many applications, and we give two examples: () connecting monolayer stress to lipid number asymmetry in order to directly measure the monolayer area modulus and () finding its strain-dependent higher-order correction by monitoring the equilibrium bilayer area.
我们提出了一种粗粒化 Cooke 脂质模型的版本，该模型经过修改可用于模拟不对称脂质膜。它的灵感来自 Wang 等人采用的一种方法[2013, 13, 1093-1106]，用于人为惩罚脂质翻转，但在应对差异压力时更为稳健，代价是每个脂质增加一个珠子，同时增加计算开销。双层不对称性最终会在一个依赖于系统大小的临界差分压力下崩溃，这个临界差分压力可以通过一个简单的分析模型来预测。我们重新测量了新模型的许多重要材料参数，发现它与典型的流体脂质膜一致。维持稳定的应力不对称性有许多应用，我们给出了两个例子：（）将单层应力与脂质数量不对称性联系起来，以便直接测量单层面积模量；（）通过监测平衡双层面积来找到其应变相关的更高阶修正。
