Editing Enzyme (section)

=== Dynamics ===

{{See also|Protein dynamics}}

Enzymes are not rigid, static structures; instead they have complex internal dynamic motions – that is, movements of parts of the enzyme's structure such as individual amino acid residues, groups of residues forming a [[turn (biochemistry)|protein loop]] or unit of [[protein secondary structure|secondary structure]], or even an entire [[protein domain]]. These motions give rise to a [[conformational ensemble]] of slightly different structures that interconvert with one another at [[thermodynamic equilibrium|equilibrium]]. Different states within this ensemble may be associated with different aspects of an enzyme's function. For example, different conformations of the enzyme [[dihydrofolate reductase]] are associated with the substrate binding, catalysis, cofactor release, and product release steps of the catalytic cycle,<ref>{{cite journal | vauthors = Ramanathan A, Savol A, Burger V, Chennubhotla CS, Agarwal PK | title = Protein conformational populations and functionally relevant substates | journal = Accounts of Chemical Research | volume = 47 | issue = 1 | pages = 149–156 | date = January 2014 | pmid = 23988159 | doi = 10.1021/ar400084s | osti = 1565147 }}</ref> consistent with [[catalytic resonance theory]]. The transitions between the different conformations during the catalytic cycle involve internal [[Viscoelasticity|viscoelatic]] motion that is facilitated by high-[[Strain (mechanics)|strain]] regions where amino acids are rearranged.<ref>{{Cite journal |last=Weinreb |first=Eyal |last2=McBride |first2=John M. |last3=Siek |first3=Marta |last4=Rougemont |first4=Jacques |last5=Renault |first5=Renaud |last6=Peleg |first6=Yoav |last7=Unger |first7=Tamar |last8=Albeck |first8=Shira |last9=Fridmann-Sirkis |first9=Yael |last10=Lushchekina |first10=Sofya |last11=Sussman |first11=Joel L. |last12=Grzybowski |first12=Bartosz A. |last13=Zocchi |first13=Giovanni |last14=Eckmann |first14=Jean-Pierre |last15=Moses |first15=Elisha |date=2025-03-28 |title=Enzymes as viscoelastic catalytic machines |url=https://www.nature.com/articles/s41567-025-02825-9 |journal=Nature Physics |language=en |pages=1–12 |doi=10.1038/s41567-025-02825-9 |issn=1745-2481}}</ref>