Editing Protein (section)

=== Structure ===

[[File:KendrewMyoglobin.jpg|thumb|upright=1.15|[[John Kendrew]] with model of myoglobin in progress]]

With the development of [[X-ray crystallography]], it became possible to determine protein structures as well as their sequences.<ref name="Stoddart">{{cite journal | vauthors = Stoddart C |title=Structural biology: How proteins got their close-up |journal=Knowable Magazine |date=1 March 2022 |doi=10.1146/knowable-022822-1 |doi-access=free }}</ref> The first [[protein structure]]s to be solved were [[hemoglobin]] by [[Max Perutz]] and [[myoglobin]] by [[John Kendrew]], in 1958.<ref name=Muirhead1963/><ref name=Kendrew1958/> The use of computers and increasing computing power has supported the sequencing of complex proteins. In 1999, [[Roger Kornberg]] sequenced the highly complex structure of [[RNA polymerase]] using high intensity X-rays from [[synchrotrons]].<ref name="Stoddart"/>

Since then, [[cryo-electron microscopy]] (cryo-EM) of large [[Macromolecular Assembly|macromolecular assemblies]]<ref name=Zhou2008/> has been developed. Cryo-EM uses protein samples that are frozen rather than crystals, and [[electron microscopy|beams of electrons]] rather than X-rays. It causes less damage to the sample, allowing scientists to obtain more information and analyze larger structures.<ref name="Stoddart"/> Computational [[protein structure prediction]] of small protein [[structural domain]]s<ref name=Keskin2008/> has helped researchers to approach atomic-level resolution of protein structures.
{{As of|April 2024}}, the [[Protein Data Bank]] contains 181,018 X-ray, 19,809 [[Cryogenic electron microscopy|EM]] and 12,697 [[Protein nuclear magnetic resonance spectroscopy|NMR]] protein structures.<ref>{{cite web |url=https://www.rcsb.org/stats/summary |title=Summary Statistics |website=RCSB PDB |access-date=2024-04-20}}</ref>