CryoEM

Cryo-electron microscopy (CryoEM) is transmission electron microscopy (TEM) performed at cryogenic temperatures. It is modernly frequently used as shorthand specifically for the reconstruction of the structure of a nanoscale objected via TEM measurements of frozen materials. For instance, to reconstruct the shape of a protein, many copies of the protein can be dispersed on a substrate and frozen (to cryogenic temperatures). TEM images can be acquired, which will contain (statistically) views of the protein from many different orientations. Using image analysis techniques, these protein images can be selected from the images, and an accurate 3D model of the protein can be reconstructed by registering all the individual projections together.

CryoEM is advancing rapidly, and allowing nearly atomic resolution reconstruction of nanostructures (proteins, viruses, etc.) that would be difficult to measure using diffraction. In particular, conventional macromolecular crystallography (MX) requires one to create large, defect-free, single crystals of a target molecule. CryoEM, on the other hand, can be used on species that do not form ordered crystals.

See Also

• Werner Kühlbrandt The Resolution Revolution Science 2014, 343 (6178), 1443-1444. doi: 10.1126/science.1251652
• CryoEM at IUCrJ: a new era