Electron cryomicroscopy: Difference between revisions
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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<ref>PMID: 10998630</ref>. Subsequently, many methods, including docking while allowing flexibility in the monomers, have been developed<ref name="kim-goldrush">PMID: 28963369</ref>. | 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<ref>PMID: 10998630</ref>. Subsequently, many methods, including docking while allowing flexibility in the monomers, have been developed<ref name="kim-goldrush">PMID: 28963369</ref>. | ||
==Your Heading Here (maybe something like 'Structure')== | |||
<StructureSection load='6SOF' size='350' side='right' caption='' scene=''> | |||
==Resolution== | ==Resolution== | ||
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A direct comparison between the quality of cryo-EM structures and crystal structures is not possible. In crystal structures, the electron density is calculated from measured structure factors and from calculated phases (in the most extreme case, half of the information is not available from experiment). Even in cases were there are experimental phases (e.g. from multiple isomorphous replacement), these are typically not available to the full resolution. Especially at resolutions below 4 Å, X-ray structures are prone to model bias in the absence of experimental phases. Cryo-EM does not have this limitation, so low resolution structures can still carry reliable information, for instance about conformational changes of known structures. For example, a 4 Å crystal structure solved by molecular replacement (i.e. no experimental phases) is not as reliable as a 4 Å cryo-EM structure. | A direct comparison between the quality of cryo-EM structures and crystal structures is not possible. In crystal structures, the electron density is calculated from measured structure factors and from calculated phases (in the most extreme case, half of the information is not available from experiment). Even in cases were there are experimental phases (e.g. from multiple isomorphous replacement), these are typically not available to the full resolution. Especially at resolutions below 4 Å, X-ray structures are prone to model bias in the absence of experimental phases. Cryo-EM does not have this limitation, so low resolution structures can still carry reliable information, for instance about conformational changes of known structures. For example, a 4 Å crystal structure solved by molecular replacement (i.e. no experimental phases) is not as reliable as a 4 Å cryo-EM structure. | ||
</StructureSection> | |||
==Temperatures (B factors)== | ==Temperatures (B factors)== | ||