髓鞘碱性蛋白对脂筏微区结构影响的模式化研究

本文主要通过原子力显微镜(AFM)和Langmuir单层膜技术研究不同浓度的髓鞘碱性蛋白(MBP)与"脂筏"(PC/SM/Cholesterol)模型相互作用形成仿生膜的物理特性。利用表面压缩模量(C_s^-1)和二维维里状态方程对π-A曲线进行分析,计算了MBP与"脂筏"单层膜分子间相互作用的第二维里系数。根据二维维里状态方程分析可得随着亚相中MBP浓度的增加,第二维里系数的值也随之变大,这说明在低的表面压力下,MBP吸附到"脂筏"模型脂膜中,且分子间的相互作用为空间排斥力。压缩模量的值表明,亚相中MBP的浓度越大,MBP与"脂筏"单层膜分子之间的作用力越强,且MBP分子将携带更多的"脂筏"分子进入亚相与其发生疏水相互作用,使得单层膜更加稀疏,可压缩性更大。AFM的表面形貌结果和曲线的分析结果相呼应,表明亚相不同浓度的MBP对"脂筏"单层膜排列和构象有着显著的影响。亚相中不同浓度的MBP与"脂筏"分子间相互作用的热力学研究为维持髓鞘结构和功能的稳定提供了有用的信息和理论基础。

Model studies of effect of myelin basic proteins on microstructure of lipid raft

The physical properties of biomimetic membranes formed by the interaction between different concentrations of myelin basic protein(MBP) and “Lipid raft”(PC/SM/Cholesterol) molecules were studied by using surface pressure-mean molecular area(π-A) and atomic force microscope(AFM). The surface compressive modulus(C_s^-1) and the two-dimensional virial equation of state were used to analyze the π-A curve, and the second virial coefficient of the molecular interaction between MBP and the “Lipid raft” monolayer was calculated. According to the two-dimensional virial equation of state analysis, it can be obtained that as the MBP concentration in the subphase increases, the value of the second virial coefficient also increases, which indicates that MBP adsorbs to the “Lipid raft” model at low surface pressure, and the intermolecular interaction is steric repulsion. The value of the compression modulus indicates that the greater the concentration of MBP in the subphase, the stronger the force between MBP and the “Lipid raft” monolayer molecule, and more MBP molecules will carry more “Lipid raft” molecules into the subphase and undergo a hydrophobic interaction with them, making the monolayer membrane more sparse and more compressible. The results of AFM and curve analysis coincide, indicating that different concentrations of MBP in the subphase have a significant effect on the arrangement and conformation of “Lipid raft” monolayer. Thermodynamic studies of the interactions between MBP with different concentrations in the subphase and “Lipid rafts” molecules provide useful information and theoretical basis for maintaining the stability of myelin structure and function.