蛋白质、胆固醇对卵磷脂囊泡稳定性的影响

Effect of Protein and Cholesterol on the Phosphatidylcholine Vesicle

用卵磷脂、胆固醇和蛋白质所形成的囊泡模拟细胞膜,利用Langmuir膜天平、Zeta电势研究卵磷脂、胆固醇和蛋白质分子之间的相互作用,以及通过停留法和TEM等方法从Gemini(双子)表面活性剂对细胞膜结构破坏方面来探讨不同组分对囊泡的稳定性的影响.实验结果表明,囊泡中的蛋白质、胆固醇和卵磷脂分子之间是相互吸引的.相对于卵磷脂囊泡,混合体系囊泡更加稳定.表面活性剂是通过静电吸引力和疏水效应嵌入囊泡的双分子层中,导致囊泡被破坏.通过动力学实验得到Gemini表面活性剂对囊泡破坏过程的活化能,进一步证明加入蛋白质、胆固醇能够使卵磷脂囊泡更加稳定.

Biological membrane with phosphatidylcholine,cholesterol and protein（bovine serum albumin,BSA） was simulated.The mixed monolayer at the air /water interface of phosphatidylcholine,cholesterol and BSA was investigated by Langmuir balance technique.The Zeta potential of cholesterol,phosphatidylcholine,BSA and their mixtures were investigated.The excess area of mixed monolyer and Zeta potential showed that there were interactions of mutual attraction among phosphatidylcholine,cholesterol and BSA.The interactions made the mixed vesicle more stable.The effect of cholesterol and BSA on the structure transformation of phosphatidylcholine vesicle was studied by means of kinetic and TEM.Gemini surfactants intercalated the bilayer via electrostatic interaction and hydrophobic effect and made the vesicle breakdown as a result.The Ea was calculated from the change of turbidity at 25,30,35,40 and 45 ℃.Comparing with previous results,the Ea of phosphatidylcholine,cholesterol and BSA was larger than phosphatidylcholine vesicle,and between those of phosphatidylcholine vesicle with cholesterol and phosphatidylcholine vesicle with BSA.On the other hand,it indicated that the phosphatidylcholine vesicles with cholesterol and（or） BSA were more stable to Gemini surfactants than phosphatidylcholine vesicle and harder to be brokendown.