Cryo-Electron Microscopy Atsuo Miyazawa 1 1Department of Picobiology, Graduate School of Life Science, University of Hyogo Keyword: 電子顕微鏡 , 急速凍結 , 非晶質氷 , 立体構造解析 , 単粒子解析 , electron microscopy , rapid freezing , vitreous ice , three-dimensional structural analysis , single particle analysis pp.639-649
Published Date 2018/6/1
DOI https://doi.org/10.11477/mf.1416201056
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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.

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