Oriented adsorption of purple membrane to cationic surfaces.
Oriented adsorption of purple membrane to cationic surfaces.
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DOI：
10.1083/jcb.77.2.611
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发表时间：
1978-05
期刊：
影响因子：
--
通讯作者：
Stoeckenius W
中科院分区：
文献类型：
--
作者：
Fisher KA;Yanagimoto K;Stoeckenius W
用定量电子显微镜研究了盐生盐杆菌紫膜（PM）分离片段在聚赖氨酸处理玻璃（PL玻璃）上的取向。三条证据支持膜的细胞质侧优先吸收的结论。首先，单层冷冻断裂揭示非随机取向，更多的断裂面（89%）是颗粒比光滑。其次，可以使用聚阳离子铁蛋白测定存在的每个膜表面的量;所有吸附的膜片段的90%被标记。第三，在缓慢风干的铂-碳阴影膜中，可以区分两种表面，“破裂”（细胞外表面）和“凹陷”（细胞质表面）。当在标准条件下使用时，超过80%出现裂缝。由阳离子底物的细胞质的选择表明，分离的PM，缓冲在pH 7.4和在光中，其细胞质表面上比其细胞外表面上具有更高的负电荷。然而，阳离子铁蛋白（CF）优先吸附到细胞外表面。取向提供了一个突出的例子，生物膜表面的不对称性，以及手段来检查的化学反应性和物理性质的表面的纯化，非囊泡膜片段。
We have investigated the orientation of isolated fragments of Halobacterium halobium purple membrane (PM) adsorbed to poly-L-lysine- treated glass (PL-glass), by quanitative electron microscopy. Three lines of evidence support the conclusion that the cytoplasmic side of the membrane is preferentially absorbed. First, monolayer freeze- fracture reveals nonrandom orientation; more fracture faces (89%) are particulate than smooth. Second, the amount of each membrane surface present can be assayed using polycationic ferritin; 90% of all adsorbed membrane fragments are labeled. Third, it is possible to distinguish two surfaces, "cracked" (the extracellular surface) and "pitted" (the cytoplasmic surface) , in slowly air-dried, platinum-carbon-shadowed membranes. When applied under standard conditions, more than 80% appear cracked. Selection for the cytoplasmic by the cationic substrate suggests that the isolated PM, buffered at pH 7.4 and in the light, has a higher negative charge on its cytoplasmic surface than on its extracellular surface. Nevertheless, cationic ferritin (CF) preferentially adsorbs to the extracellular surface. Orientation provides a striking example of biomembrane surface asymmetry as well as the means to examine the chemical reactivity and physical properties of surfaces of a purified, nonvesicular membrane fragment.