Hunt J F, McCrea P D, Zaccaï G, Engelman D M
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA.
J Mol Biol. 1997 Nov 14;273(5):1004-19. doi: 10.1006/jmbi.1997.1330.
The assessment of the physical size of integral membrane protein complexes has generally been limited to samples solubilized in non-ionic detergent, a process which may introduce artifacts of unknown scope and severity. A system has been developed that allows observation of the small angle scattering profile of an integral membrane protein while incorporated in small unilamellar phospholipid vesicles. Contrast matching of isotopically substituted phospholipid eliminates the contribution of the bilayer to the observed scattering, resulting in a profile dependent only on the structure of the individual membrane protein complexes and their spatial arrangement in the vesicle. After appropriate compensation for their spatial arrangement, information about the molecular mass and radius of gyration of the individual complexes can be obtained. The validity of the approach has been established using monomeric bacteriorhodopsin as a model system.
对整合膜蛋白复合物物理尺寸的评估通常局限于用非离子型去污剂溶解的样品，这一过程可能会引入范围和严重程度未知的假象。现已开发出一种系统，可在整合膜蛋白掺入小单层磷脂囊泡时观察其小角散射图谱。同位素取代磷脂的对比匹配消除了双层膜对观察到的散射的贡献，从而得到仅依赖于单个膜蛋白复合物结构及其在囊泡中的空间排列的图谱。在对其空间排列进行适当补偿后，可获得有关各个复合物的分子量和回转半径的信息。已使用单体细菌视紫红质作为模型系统证实了该方法的有效性。
