Cryogenic electron microscopy
Cryogenic electron microscopy (cryo-EM) is an electron microscopy (EM) technique applied on samples cooled to cryogenic temperatures and embedded in an environment of vitreous water. An aqueous sample solution is applied to a grid-mesh and plunge-frozen in liquid ethane. While development of the technique began in the 1970s, recent advances in detector technology and software algorithms have allowed for the determination of biomolecular structures at near-atomic resolution. This has attracted wide attention to the approach as an alternative to X-ray crystallography or NMR spectroscopy for macromolecular structure determination without the need for crystallization.
In 2017, the Nobel Prize in Chemistry was awarded to Jacques Dubochet, Joachim Frank, and Richard Henderson "for developing cryo-electron microscopy for the high-resolution structure determination of biomolecules in solution."
Transmission electron cryomicroscopy
- Electron crystallography, method to determine the arrangement of atoms in solids using a TEM
- MicroED, method to determine the structure of proteins and small molecules using electron diffraction from 3D crystals
- Electron cryotomography (CryoET), a specialized application of where samples are imaged as they are tilted
History of cryogenic electron microscopy
In the 1960s, scientists were faced with the issue of structure determination methods using electron microscopy damaging the specimen due to high energy electron beams, so cryogenic electron microscopy was considered to overcome this issue as it was expected that low temperatures would reduce beam damage. In 1980, Erwin Knapek and Jacques Dubochet published commenting on beam damage at cryogenic temperatures sharing observations that:
Thin crystals mounted on carbon film were found to be from 30 to 300 times more beam-resistant at 4 K than at room temperature... Most of our results can be explained by assuming that cryoprotection in the region of 4 K is strongly dependent on the temperature.
However, these results were not reproducible and amendments were published in the Nature international journal of science just 2 years later informing that the beam resistance was less significant than initially anticipated. The protection gained at 4 K was closer to “tenfold for standard samples of L-valine,” than what was previously stated.
In 2018, chemists realized that electron diffraction can be used to readily determine the structures of small molecules that form needle-like crystals, structures that would otherwise need to be determined from X-ray crystallography, by growing larger crystals of the compound.
Scanning electron cryomicroscopy
- Cheng Y, Grigorieff N, Penczek PA, Walz T (April 2015). "A primer to single-particle cryo-electron microscopy". Cell. 161 (3): 438–449. doi:10.1016/j.cell.2015.03.050. PMC 4409659. PMID 25910204.
- Cressey D, Callaway E (October 2017). "Cryo-electron microscopy wins chemistry Nobel". Nature. 550 (7675): 167. Bibcode:2017Natur.550..167C. doi:10.1038/nature.2017.22738. PMID 29022937.
- Nannenga, Brent L; Shi, Dan; Leslie, Andrew G W; Gonen, Tamir (2014-08-03). "High-resolution structure determination by continuous-rotation data collection in MicroED". Nature Methods. 11 (9): 927–930. doi:10.1038/nmeth.3043. PMC 4149488. PMID 25086503.
- Jones, Christopher G.; Martynowycz, Michael W.; Hattne, Johan; Fulton, Tyler J.; Stoltz, Brian M.; Rodriguez, Jose A.; Nelson, Hosea M.; Gonen, Tamir (2018-11-02). "The CryoEM Method MicroED as a Powerful Tool for Small Molecule Structure Determination". ACS Central Science. 4 (11): 1587–1592. doi:10.1021/acscentsci.8b00760. PMC 6276044. PMID 30555912.
- de la Cruz, M Jason; Hattne, Johan; Shi, Dan; Seidler, Paul; Rodriguez, Jose; Reyes, Francis E; Sawaya, Michael R; Cascio, Duilio; Weiss, Simon C (2017). "Atomic-resolution structures from fragmented protein crystals with the cryoEM method MicroED". Nature Methods. 14 (4): 399–402. doi:10.1038/nmeth.4178. PMC 5376236. PMID 28192420.
- Dubochet J, Knapek E (April 2018). "Ups and downs in early electron cryo-microscopy". PLoS Biology. 16 (4): e2005550. doi:10.1371/journal.pbio.2005550. PMC 5929567. PMID 29672565.
- Knapek E, Dubochet J (August 1980). "Beam damage to organic material is considerably reduced in cryo-electron microscopy". Journal of Molecular Biology. 141 (2): 147–61. doi:10.1016/0022-2836(80)90382-4. PMID 7441748.
- Newmark P (30 September 1982). "Cryo-transmission microscopy Fading hopes". Nature. 299 (5882): 386–387. Bibcode:1982Natur.299..386N. doi:10.1038/299386c0.
- Gruene T, Wennmacher JT, Zaubitzer C, Holstein JJ, Heidler J, Fecteau-Lefebvre A, De Carlo S, Müller E, Goldie KN, Regeni I, Li T, Santiso-Quinones G, Steinfeld G, Handschin S, van Genderen E, van Bokhoven JA, Clever GH, Pantelic R (October 2018). "Rapid structure determination of microcrystalline molecular compounds using electron diffraction". Angewandte Chemie. 57 (50): 16313–16317. doi:10.1002/anie.201811318. PMID 30325568.