Department of Chemical Engineering, University of California, Berkeley, 101B Gilman Hall, Berkeley, California 94720-1462, USA.
J Phys Chem B. 2010 Aug 19;114(32):10451-61. doi: 10.1021/jp103903s.
In this paper, we present a coarse-grained model of a hydrated saturated phospholipid bilayer (dimyristoylphosphatidylcholine, DMPC) containing cholesterol that we study using a hybrid dissipative particle dynamics-Monte Carlo method. This approach allows us to reach the time and length scales necessary to study structural and mechanical properties of the bilayer at various temperatures and cholesterol concentrations. The properties studied are the area per lipid, condensation, bilayer thickness, tail order parameters, bending modulus, and area compressibility. Our model quantitatively reproduces most of the experimental effects of cholesterol on these properties and reproduces the main features of the experimental phase and structure diagrams. We also present all-atom simulation results of the system and use these results to further validate the structure of our coarse-grained bilayer. On the basis of the changes in structural properties, we propose a temperature-composition structure diagram, which we compare with the experimental phase and structure diagrams. Attention is paid to the reliability and interpretation of the model and simulation method and of the different experimental techniques. The lateral organization of cholesterol in the bilayer is discussed.
本文提出了一种含有胆固醇的水合饱和磷脂双层（二肉豆蔻酰磷脂酰胆碱，DMPC）的粗粒度模型，我们使用混合耗散粒子动力学-蒙特卡罗方法对其进行了研究。这种方法使我们能够达到研究双层在不同温度和胆固醇浓度下的结构和力学性质所需的时间和长度尺度。研究的性质包括每个脂质的面积、凝聚、双层厚度、尾部序参数、弯曲模量和面积压缩性。我们的模型定量再现了胆固醇对这些性质的大多数实验影响，并再现了实验相和结构图的主要特征。我们还展示了系统的全原子模拟结果，并使用这些结果进一步验证了我们粗粒度双层的结构。基于结构性质的变化，我们提出了一个温度-组成结构图，并将其与实验相和结构图进行了比较。我们关注模型和模拟方法以及不同实验技术的可靠性和解释。讨论了胆固醇在双层中的侧向组织。
