Electron cryomicroscopy
Single-particle electron cryomicroscopy (cryo-EM) has become an important method for determining macromolecular structures. It is the basis for the 2017 Nobel Prize in Chemistry. Although resolution is usually poorer than that obtained by X-ray crystallography, cryo-EM has the great advantage of not requiring crystallization[1]. Cryo-EM is particularly suited to determination of the structures of large complexes containing multiple proteins or nucleic acids, often the most difficult to crystallize. Early studies showed that docking of monomer crystal structures into even poor-resolution (e.g. 15 Å) cryo-EM maps of larger assemblies could reliably predict structure[2]. In 2018, the median resolution of cryo-EM structures deposited in the Protein Data Bank was 3.8 Å (improved from 4.3 Å in 2016)[3]. For comparison, the median resolution of X-ray crystallographic entries in the PDB has been 2.0 Å for many years[3].
VideosVideos
- 3 min video explaining the principles of cryo-EM.
- 2017 Nobel laureate Richard Henderson explains the history of cryo-EM in this 5 min video.
Electron cryo-microscopy, Cryo-electron microscopy and Cryo-EM redirect to this page.
Notes and ReferencesNotes and References
- ↑ Obtaining highly-ordered crystals is perhaps the major obstacle to determination of structure by X-ray diffraction.
- ↑ Roseman AM. Docking structures of domains into maps from cryo-electron microscopy using local correlation. Acta Crystallogr D Biol Crystallogr. 2000 Oct;56(Pt 10):1332-40. PMID:10998630
- ↑ 3.0 3.1 See Cryo-EM Resolution compared with X-ray diffraction resolution: tinyurl.com/method-vs-resolution.