胆固醇对脂双层结构影响的SAXS和STM研究

摘要

用小角X射线散射(SAXS)和扫描隧道显微镜(STM)技术分别研究了模拟生物膜脂质体的结构以及胆固醇对生物膜双层结构的影响．结果表明，在扫描隧道显微镜照片中，磷脂分子在石墨表面形成规则的二维点状排列图像；磷脂胆固醇脂质体在石墨表面形成规则的二维波纹状排列图像。用小角X射线散射研究结果表明，DPPC脂质体是片层相结构，DPPC＋Chol脂质体是复相片层结构，DPPE＋Chol脂质体是片层立方相结构，DPPC＋DPPE＋Chol脂质体是立方六角形相结构。%The effect of cholesterol on the phospholipid bilayer structureand polymorphism of liposomes have been investigated by method of the small angle X-ray diffraction (SAXS) and by the technique of scanning tunneling microscope (STM).The experiments proved that the STM images of the two-dimensional point array of the phospholipid molecules formed on graphite and that the STM images of the two-dimensional corrugated array of the liposomes of phospholipid and cholesterol formed on graphite.By using small angle X-ray diffraction we demonstrate the presence of lamellar phase in the DPPC liposomes.The cholesterol induces spontaneous formation of a complex lamellar phase in the DPPC-cholesterol liposomes and promotes formation of lamellar and cubic phase in the DPPE-cholesterol liposomes.The presence of cholesterol allowed the system to organize in cubic and hexagonal phase in DPPC-DPPE-cholesterol liposomes.