Electron microscopy of the conformational changes of alpha 2‐macroglobulin from human plasma
Electron microscopy of the conformational changes of alpha 2‐macroglobulin from human plasma
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电子显微镜观察人血浆中 α2-巨球蛋白的构象变化
DOI：
10.1002/j.1460-2075.1985.tb02321.x
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
E. Delain
中科院分区：
文献类型：
--
作者：
J. Tapon‐Bretaudiére;A. Bros;E. Couture‐Tosi;E. Delain
高分辨率电子显微镜显示，新鲜人血浆中完全活性的α 2-巨球蛋白（α 2 M）呈现出非常典型的四聚体结构。本文首次描述了α 2 M分子的这种天然构象，沿着描述了其在负染色制备物中的各种取向。尽管天然形式对灭活敏感，但除了使用铵盐时，戊二醛固定对其观察是不必要的。当用胰蛋白酶、凝血酶或甲胺处理蛋白质时，α 2 M的四聚体结构发生剧烈的构象变化，如文献中已描述的典型）+（结构的出现所证明。该第二构象的各个方面对应于染色膜中分子的不同取向，并且取决于支撑物的性质。
High resolution electron microscopy reveals that fully active alpha 2‐macroglobulin (α2M) from fresh human plasma presents a very characteristic tetrameric structure. This native conformation of the α2M molecule is described here for the first time, along with its various orientations in negatively stained preparations. Although the native form is sensitive to inactivation, glutaraldehyde fixation is not necessary for its observation except when ammonium salts are used. The tetrameric structure of α2M undergoes a drastic conformational change when the protein is treated either with trypsin, thrombin or methylamine, as evidenced by the appearance of the typical)+(structure already described in the literature. The various aspects of this second conformation correspond to different orientations of the molecules in the stain film, and depend upon the nature of the support.