Electron cryomicroscopy: Difference between revisions
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[http://tinyurl.com/method-vs-resolution tinyurl.com/method-vs-resolution].</ref>. For comparison, the median resolution of X-ray crystallographic entries in the PDB has been 2.0 Å for many years<ref name="mvr" />. | [http://tinyurl.com/method-vs-resolution tinyurl.com/method-vs-resolution].</ref>. For comparison, the median resolution of X-ray crystallographic entries in the PDB has been 2.0 Å for many years<ref name="mvr" />. | ||
In 2015, Cheng, Grigorieff, Penczek & Walz concluded: <blockquote> | |||
"''Resolution'' in single-particle EM is ... a somewhat arbitrarily chosen cut-off level ...." "... it is the opinion of the authors that there is currently no real ''gold standard'' procedure for structure refinement and resolution estimation of an EM map."<ref name="primer" />. | "''Resolution'' in single-particle EM is ... a somewhat arbitrarily chosen cut-off level ...." "... it is the opinion of the authors that there is currently no real ''gold standard'' procedure for structure refinement and resolution estimation of an EM map."<ref name="primer" />. | ||
</blockquote> | |||
When resolution improves by a factor of 2, the available data (to support the coordinate model) goes up by a factor of 8. For example, a 2.4 Å resolution structure is a great improvement over a 3.0 Å resolution structure because the number of available measurements doubles. | When resolution improves by a factor of 2, the available data (to support the coordinate model) goes up by a factor of 8. For example, a 2.4 Å resolution structure is a great improvement over a 3.0 Å resolution structure because the number of available measurements doubles. | ||