牛血清蛋白对二硬脂酰基磷脂酰乙醇胺单层膜结构的影响

摘要

The effect of bovine serum albumin(BSA) on the 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) monolayer at air-water interface was investigated by Langmuir-blodgett(LB) technique and atomic force microscopy(AFM) observation. The surface pressure-mean molecular area(π-A) isotherms, adsorption curves and compression-expansion cycle curves of DSPE monolayers were obtained by changing the pH values and the concentration of BSA. The results indicated that the presence of BSA in the subphase had a great influence on the compressibility, stability and phase transition behavior of DSPE monolayers. The adsorption kinetic indicated that BSA was adsorbed onto DSPE monolayers and a threshold value existed, which was affected by the pH value. Analysis of experimental data showed that most hydrophobic residues of BSA were exposed to water at pH= 3, so the interaction between BSA and DSPE was strongest. However, the interaction was the weakest at pH = 7 because less hydrophobic residues were exposed to water. The change of surface morphology structure observed by AFM was consistent with the results obtained from curves. This study provides an important experimental basis and theoretical basis for understanding the interaction mechanism between serum proteins and phospholipid molecules.%利用Langmuir-Blodgett(LB)技术结合原子力显微镜(AFM),研究了牛血清蛋白(BSA)在气/液界面上对二硬脂酰基磷脂酰乙醇胺(DSPE)单层膜结构的影响.通过改变亚相的pH值和BSA浓度,获得了不同条件下DSPE单层膜的等温线、 吸附曲线和压缩循环曲线等.实验结果表明,亚相中BSA的存在对DSPE单层膜的压缩性、 稳定性以及相变行为产生了较大的影响.吸附动力学结果表明,DSPE单层膜对BSA分子的吸附量存在一定的阈值,且该阈值的大小与亚相pH值相关.通过分析实验数据可知,当亚相pH=3时,BSA的疏水残基几乎全部暴露在外面,2种分子之间的相互作用最强;而pH=7时,BSA仅有少量的疏水残基暴露在外面,2种分子之间的相互作用最弱.原子力显微镜观测到的单层膜形态变化特点与曲线分析结果一致.该研究为了解牛血清蛋白与磷脂分子之间的相互作用机理提供了重要的实验基础和理论依据.