title: [Preparation of liposome containing bacteriorhodopsin with  natural  preferred orientation of its transient photoresponse].
abstract: 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.
authors.affiliation: Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China. jdding1@fudan.edu.cn
authors.forename: Li
authors.initials: L
authors.lastname: Huang
authors.forename: Ming
authors.initials: M
authors.lastname: Ming
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.forename: Jian
authors.initials: J
authors.lastname: Liu
authors.forename: Qing-Guo
authors.initials: QG
authors.lastname: Li
authors.forename: Jian-Dong
authors.initials: JD
authors.lastname: Ding
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D001436:Bacteriorhodopsins / Q000737:chemistry* / Q000302:isolation & purification / Q000648:ultrastructure; D019617:Halobacterium salinarum / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008081:Liposomes / Q000737:chemistry*; D008854:Microscopy, Electron; D017433:Protein Structure, Secondary; D013010:Sonication; D013997:Time Factors
chemical_list: D008081:Liposomes; D015060:1,2-Dipalmitoylphosphatidylcholine; D001436:Bacteriorhodopsins