“正常”膜蛋白取向的细菌视紫红质脂质体制备及其瞬态光学响应  

Preparation of Liposome Containing Bacteriorhodopsin with "Natural" Preferred Orientation and Detection of Its Transient Photoresponse

作　　者：黄力[1] 明明[1] 刘嘉[1] 刘坚[1] 李庆国[2] 丁建东[1] 

机构地区：[1]复旦大学高分子科学系,聚合物分子工程教育部重点实验室,上海200433 [2]复旦大学生命科学院生理学与生物物理学系,上海200433

出　　处：《生物化学与生物物理学报》2003年第4期391-395,共5页

基　　金：国家自然科学基金资助项目 (No .2 982 5 10 9;No .2 0 1740 0 6);教育部高等学校优秀青年教师教学和科研奖励基金;国家重点基础研究发展规划项目 (973计划 )资助项目 (No.G19990 5 43 0 6 0 3 );国家高技术研究发展计划 (863计划 )资助项目 (No .2 0 0 1AA2 15 45 1

摘　　要：细菌视紫红质 (bR)是嗜盐菌质膜上的一种跨膜蛋白质 ,有其独特的光驱质子泵功能 ,可以被定向组装到磷脂脂质体膜上 ,并且表现出和细胞膜上相反的取向。通过细菌培养和细胞膜分离 ,获得了含bR蛋白质的紫膜悬浮体系 ,在pH =2 .5时将bR悬浮液和两亲性的DPPC磷脂混合、通过自组装的方式形成了含bR膜蛋白的磷脂脂质体 ,并通过瞬态光学响应测量考察了bR的取向和质子泵生物活性。结果表明 ,bR膜蛋白可以被整合到DPPC的脂质体膜上 ;蛋白质的质子泵运行规律的测量进一步验证了在酸性条件下所制备的脂质体上bR保持了不寻常的择优取向 ,与细胞膜上的“正常”取向一致 ,而与绝大多数文献报道的中性条件下制备的脂质体质子泵取向相反。Bacteriorhodopsin is a membrane protein of halobacteria and functions as a light-driven protein pump. After we isolated bR from cultured halobacteria, bR was mixed with amphiphilic DPPC under different pH. The liposomes were formed after sonication. The remaining biological activity of bR as a proton pump was then verified and pulsed-light-induced proton movement was detected, while liposomes were observed via TEM and light scattering. Although there was no noticeable difference in morphologies of both vesicles formed at pH=2.5 and pH=7.0, the orientations of bR in both liposomes were found to be opposite under these two conditions. This experiment confirmed that the protein bR, when self-assembling into liposomes under acid medium, kept the similar orientation as in the natural plasmid membrane. Such a “normal” orientation was, however, different from most of reports in the literature about liposomes prepared under normal neutral conditions.

关 键 词：细菌视紫红质 嗜盐菌 跨膜蛋白质 瞬态光学响应 脂质体 自组装 生物膜 膜蛋白取向 光驱质子泵功能 

分 类 号：Q632[生物学—生物物理学]