[Cryo-Electron Microscopy].
[Cryo-Electron Microscopy].
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DOI：
10.11477/mf.1416201056
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发表时间：
2018-06
期刊：
影响因子：
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通讯作者：
A. Miyazawa
中科院分区：
文献类型：
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作者：
A. Miyazawa
低温电子显微镜(Cryo-EM)包括三种技术方法：(1)玻璃体埋冰的快速冷冻；(2)冷冻水化样品的观察；(3)用于三维结构分析的图像处理。三维结构分析可以通过三种不同的方式进行。电子结晶学可以在最高分辨率(原子水平)破译膜蛋白的结构。单颗粒分析现在可以在近原子水平上测定溶液中高度纯化的蛋白质和复合体(非晶态生物分子)的结构。电子断层扫描可以显示细胞和/或组织的超薄切片的三维结构。通过电子断层扫描获得的结构的分辨率不是很高(纳米级)，但它有可能揭示生物分子组件或细胞细胞器的单独结构，在接近自然的细胞条件下。低温电子显微镜的一个技术发展应该是引入一种新的用于直接探测电子的cmos照相机。使用这样的相机，可以记录一个短电影(通常是2-3秒)，其中包括许多图像，每个图像的曝光时间为几百毫秒。这样的薄膜具有证明的价值，因为它可以补偿电子束照射引起的样品运动。图像处理算法和计算机程序的改进对于实现更高分辨率的三维结构也是必不可少的。
Cryo-electron microscopy (cryo-EM) includes three technical methods, (1) rapid freezing for vitreous ice-embedding, (2) observation of frozen hydrated specimens, and (3) image processing for three-dimensional structural analysis. The three-dimensional structural analysis can be performed in three different ways. Electron crystallography can decipher the structure of membrane proteins at the highest resolution (atomic level). Single particle analysis now allows the determiration of the structure of highly purified proteins and complexes (non-crystalline biomolecules) in solution at the near-atomic level. Electron tomography can reveal the three-dimensional structure of an ultrathin-section of the cells and/or tissues. The resolution of the structure obtained by electron tomography is not very high (nm level), however it is possible to reveal the individual structures of biomolecular assemblies or cellular organelles, in close-to-native condition in the cell. A technical development for cryo-EM should be the introduction of a new CMOS camera for the direct detection of electrons. Using such camera, a short movie (usually 2-3 seconds), comprising numerous images with a few hundred milliseconds exposure each can be recorded. Such a movie has a demonstrated value, as it can compensate for the specimen motion induced by irradiation of electron beam. Improvements in image processing algorithms and computer programs are also essential for achieving three-dimensional structures at a better resolution.