Kim David T, Blanch Harvey W, Radke Clayton J
Department of Chemical Engineering, University of California, 201 Gilman Hall, Berkeley, CA 94720-1462, USA.
Colloids Surf B Biointerfaces. 2005 Apr 10;41(4):263-76. doi: 10.1016/j.colsurfb.2005.01.002.
The organization of bacteriorhodopsin (bR) within reconstituted purple membranes (RPM) was examined using atomic force microscopy (AFM). Five reconstituted species were examined: RPM 3 (bR/native polar lipids/dimyristoylphosphatidylcholine (DMPC) in a 1:9:14 molar ratio), RPM 4 (bR/native polar lipids in a 1:7 molar ratio), RPM 5 (bR/native polar lipids/1,2-di-O-phytanyl-sn-glycerol in a 1:3.5:6.1 molar ratio), RPM 6 (bR/native polar lipids/1,2-di-O-phytanyl-sn-glycero-3-phosphocholine in a 1:3.5:4.9 molar ratio), and RPM 7 (bR/native polar lipids/1,2-diphytanoyl-sn-glycero-3-[phospho-L-serine] in a 1:3.5:4.6 molar ratio). RPM 3 patches adsorbed onto mica exhibit domains of crystallized bR trimers arranged in a hexagonal packing structure, similar to those found in native purple membrane (NPM). These domains are enclosed by DMPC-rich regions. RPM 4 patches were observed to have larger domains of crystallized bR, with trimer orientation 30 degrees different from that found in NPM. The bR-rich domains are enclosed by a large, protein-free, lipid-rich region. The topography of RPM 5 was difficult to resolve as the surface had no discernable patterns or structure. The topographies of RPM 6 and 7 were similar to that found in RPM 3 in that higher domains were formed within the patch adsorbed onto mica. They may contain protein-rich regions, but clear images of protein arrangement could not be obtained using AFM. This may be a result of imaging limitations or of the lack of organization of bR within these domains.
利用原子力显微镜（AFM）研究了重组紫膜（RPM）中细菌视紫红质（bR）的组织情况。研究了五种重组物种：RPM 3（bR/天然极性脂质/二肉豆蔻酰磷脂酰胆碱（DMPC），摩尔比为1:9:14）、RPM 4（bR/天然极性脂质，摩尔比为1:7）、RPM 5（bR/天然极性脂质/1,2 - 二 - O - 植烷基 - sn - 甘油，摩尔比为1:3.5:6.1）、RPM 6（bR/天然极性脂质/1,2 - 二 - O - 植烷基 - sn - 甘油 - 3 - 磷酸胆碱，摩尔比为1:3.5:4.9）和RPM 7（bR/天然极性脂质/1,2 - 二植烷酰 - sn - 甘油 - 3 - [磷酸 - L - 丝氨酸]，摩尔比为1:3.5:4.6）。吸附在云母上的RPM 3斑块呈现出结晶化的bR三聚体结构域，排列成六边形堆积结构，类似于天然紫膜（NPM）中的结构。这些结构域被富含DMPC的区域包围。观察到RPM 4斑块具有更大的结晶化bR结构域，三聚体取向与NPM中的相差30度。富含bR的结构域被一个大的、无蛋白质、富含脂质的区域包围。RPM 5的表面形貌难以分辨，因为表面没有可识别的图案或结构。RPM 6和7的表面形貌与RPM 3相似，即吸附在云母上的斑块内形成了较高的结构域。它们可能包含富含蛋白质的区域，但使用AFM无法获得蛋白质排列的清晰图像。这可能是成像限制或这些结构域内bR缺乏组织的结果。
