介观模拟研究温度对DPPC磷脂双层膜结构的影响

The influence of temperature on DPPC membrane:Mesoscopic simulation study

生物膜作为生物体的一种基本组成单元,在各种生命活动中占据重要地位。生物膜的结构和功能的稳定性是其发挥一切生理功能的前提。本文以DPPC磷脂双分子层为生物膜模型,采用基于Martini力场的粗粒化模拟方法,考察了温度对DPPC磷脂双层膜结构、形态和功能的影响。结果表明,315 K为DPPC磷脂双层膜的相转变温度;温度升高,DPPC分子间隙增加,尾链发生折叠弯曲,引起脂均面积增大,厚度减小,流动性增加;DPPC双层膜中甘油酯基团组成的栅栏区为膜中分子排列最有序的区域,也是阻碍小分子透膜的主要屏障区。研究结果不仅有助于更好地阐释生物膜的结构形态和功能之间的关系,也有助于理解药物与膜的相互作用,指导临床用药。

Biomembranes, as an essential component unit of organism, paly an important role in various vital activities. The stability of the structure and function of biomembranes is the precondition of their physiological functions. In this work, the DPPC bilayer was adopted as a model of biomembrane, and a mesoseopie simulation method based on Martini force field was used to study the influence of temperature on DPPC bilayer＇s structure, morphology and function. The simulation results show that the phase transition temperature of DPPC bilayer is 315K. What is more, the intermolecular gap of DPPC turns to increase and the DPPC alkyl chains tend to folding and bending when temperature raising, which lead to the increase of area per lipid of DPPC and the decrease of the bilayer thickness. The results also reveal that, the most ordered region of DPPC bilayer, which is composed of the glyceride group, is the main barrier for small molecules permeating bilayers. These findings not only help to explain the relationship between the structures and functions of biomembranes explicitly, but can also help us to understand the self-regulation mechanism of biomembranes responding to the change of the surroundings.