Development of the State-of-the-Arts Electron Cryomicroscope, “CRYO ARM”
Abstract: The structural analysis of a biological samples are carried out by X-ray crystallography, NMR and electon cryomicroscopy(CryoEM). Only until a few years ago, the resolution of the structural analysis by CryoEM were not so high than the others. But by development of direct electron detection camera, the resolution by CryoEM was dramatically improved. Therefore we have been developing new cryoEM with JEOL to high resolution analysis more easily. This high-end CryoEM equipped with an automatic sample exchange device that can automatically, cryo pole piece specialized for single particle image analysis and Ω type energy filter for contrast improvement.
To evaluate the resolution by single particle image analysis, β-galactosidase was used as a test sample. The 2,500 images were automatically collected by “JADAS” produced by JEOL. Finally 88,000 particle images were used for single particle image analysis by Relion. As a result, the resolution was achieved to 2.6 Å, the density map of some aromatic ring had a hole, and Mg ion density was clearly observed. This resolution is one of highest one in the world at 200kV CryoEM. We demonstrated that the Cryo ARM 200 is possible to sufficiently analyze high resolution analysis.
Key words: Electron cryomicroscope, Single particle image analysis, Cryo ARM, High resolution structural analysis, Atomic resolution