Electron cryomicroscopy: Difference between revisions
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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" /><ref name="marques2019" />. Wang (2017)<ref name="wang2017">PMID: 28543856</ref> provided a way to convert electron potential maps to <i>charge density maps</i> (using [[Chimera]]), where densities have better resolution and better reflect the positions of atomic nuclei. | 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" /><ref name="marques2019" />. Wang (2017)<ref name="wang2017">PMID: 28543856</ref> provided a way to convert electron potential maps to <i>charge density maps</i> (using [[Chimera]]), where densities have better resolution and better reflect the positions of atomic nuclei. | ||
===Visualizing EM Maps=== | |||
[[FirstGlance in Jmol]] makes it easy to visualize EM density maps, as shown in the example at right. Be sure to click "Show More Details" in the [https://proteopedia.org/wiki/fgij/where.htm#mit Molecule Information Tab], or density maps won't be available. Then, use '''Find..''' (in the [https://proteopedia.org/wiki/fgij/where.htm#focusbox Focus Box]) to locate "503,169,360". (These happen to be unambiguous sequence numbers for HEC503, HIS169, and HIS360.) Click on "EM Density Map". | |||
===The Electron Microscopy Data Bank=== | ===The Electron Microscopy Data Bank=== | ||