Electron cryomicroscopy: Difference between revisions
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==Density Maps== | ==Density Maps== | ||
The result of a cryo-EM experiment is a density map. Just as for X-ray diffraction, it is then necessary to fit an atomic model optimally into the map. | The result of a cryo-EM experiment is a density map. Just as for [[X-ray diffraction]], it is then necessary to fit an atomic model optimally into the map. | ||
Cryo-EM "has the advantage of recording images containing both amplitude and phase information, so there is no phase problem as in [X-ray] crystallography"<ref name="rosenthal2019">PMID: 30713698</ref>. | Cryo-EM "has the advantage of recording images containing both amplitude and phase information, so there is no phase problem as in [X-ray] crystallography"<ref name="rosenthal2019">PMID: 30713698</ref>. | ||
Electrons are diffracted by the charges in the sample, in contrast to X-rays that are diffracted by electron density. Consequently, EM maps may be termed "electron potential maps"<ref name="rosenthal2019" />, "Coulomb potential maps"<ref name="marques2019">PMID: 31400843</ref>, or "electric potential maps"<ref name="wang2016">PMID: 27706888</ref>. Electron densities are all positive, while electron potential maps can be positive or negative<ref name="wang2016" />. | Electrons are diffracted by the charges in the sample, in contrast to X-rays that are diffracted by electron density, producing [[electron density maps]]. Consequently, EM maps may be termed "electron potential maps"<ref name="rosenthal2019" />, "Coulomb potential maps"<ref name="marques2019">PMID: 31400843</ref>, or "electric potential maps"<ref name="wang2016">PMID: 27706888</ref>. Electron densities are all positive, while electron potential maps can be positive or negative<ref name="wang2016" />. | ||
===The Electron Microscopy Data Bank=== | ===The Electron Microscopy Data Bank=== | ||