磷脂酰乙醇胺单分子膜的相变因素分析及原子力显微镜观测  

The research on the influence factor of the phase transition and atomic force microscope observation of the phosphatideyl ethanolamines

作　　者：刘颖[1] 孙润广[1] 

机构地区：[1]陕西师范大学物理与信息技术学院生物物理与生物医学工程研究室,西安710062

出　　处：《原子与分子物理学报》2007年第5期1065-1072,共8页Journal of Atomic and Molecular Physics

基　　金：国家自然科学基金(20572067);教育部科学技术研究重点项目(104167)

摘　　要：通过π-A曲线(π:膜对浮片所施之力,A:单分子所占的面积)研究浓度、pH值、温度以及蔗糖对磷脂酰乙醇胺相变的影响.实验表明:(1)当浓度较高时,磷脂酰乙醇胺的π-A曲线随着浓度的增加重合性较好,平均分子面积和表面膜压有较好的对应.当浓度较低时,π-A曲线重合性较差,在低密度情况下,磷脂酰乙醇胺分子的排列不紧密,致使分子的随机运动对膜压的影响较大;(2)亚相处于较强的酸性或者碱性状态下均会使磷脂酰乙醇胺分子的相变变慢,pH值过高或过低都会对膜有较大的破坏作用;(3)当温度逐渐增大,而保持平均分子面积不变时,随着温度的增加,t-pa曲线(温度-膜压)逐渐由一条直线变成抛物线,这说明随着温度的增加磷脂酰乙醇胺凝聚膜会向液态扩张膜转变,即随着温度的增加相变延迟;(4)蔗糖对磷脂酰乙醇胺单分子膜有较强的稳定作用,且这种作用在生理条件下最为明显.用原子力显微镜直接观测了不同压力下转移至云母表面分子层的形貌特征,进一步解释了磷脂酰乙醇胺单分子膜相变的微观分子机制.This text draw how the density, pH value, temperature and sucrose influence the phase change of the phosphatideyl ethanolamine by analyzing the π-A curves of the phosphatideyl ethanolamine molecule membrane whose subphase is distilled water or sucrose solution. The experiment indicates as follows： （1） When the concentration is higher, the π-A curves of the phosphatideyl ethanolamine molecule membrane.are coincident better as the increasing concentration of the DEPE aether solution. When the concentration is lower, π-A curves of the phosphatideyl ethanolamine molecule membrane aren＇t coincident very well. The result of the experiment indicate that when the concentration is lower, the phosphatideyl ethanolamine molecules aren＇t close to each other, which make the influence of the molecule moving at random on the membrane pressure become larger, （2） The conditions which are acidity and alkali will make the phase transition of the phos- phatideyl ethanolamine molecules membrane become slower. The pH value which is much lower or higher will destroy the phosphatideyl ethanolamine molecules membrane badly, （3）When the temperature is crescent and we keep the average area of the molecule not to change, t-pa curve （temperature-membrane pressure ） turn to parabola from beeline gradually as the increasing of temperature, which prove that membrane become coacer- vation state from dilatation state, namely as the transition delays as the increasing of temperature, （4）The su- crose has stabilization to the phosphatideyl ethanolamine molecule membrane, and it is much more obvious on the physiological condition. Then we observed the structure of the phosphatideyl ethanolamines LB membrane that was transferred under different pressure by AFM, and give the molecular mechanism further.

关 键 词：膜与细胞生物物理 磷脂酰乙醇胺相变因素 π-A曲线 原子力显微镜 

分 类 号：Q633[生物学—生物物理学]