Editing Enzyme (section)

== Evolution ==
Similar to any other protein, enzymes change over time through [[mutation]]s and sequence divergence. Given their central role in [[metabolism]], enzyme evolution plays a critical role in [[adaptation]]. A key question is therefore whether and how enzymes can change their enzymatic activities alongside. It is generally accepted that many new enzyme activities have evolved through [[gene duplication]] and mutation of the duplicate copies although evolution can also happen without duplication. One example of an enzyme that has changed its activity is the ancestor of [[methionyl aminopeptidase]] (MAP) and creatine amidinohydrolase ([[creatinase]]) which are clearly homologous but catalyze very different reactions (MAP removes the amino-terminal [[methionine]] in new proteins while creatinase hydrolyses [[creatine]] to [[sarcosine]] and [[urea]]). In addition, MAP is metal-ion dependent while creatinase is not, hence this property was also lost over time.<ref>{{cite journal | vauthors = Murzin AG | title = Can homologous proteins evolve different enzymatic activities? | journal = Trends in Biochemical Sciences | volume = 18 | issue = 11 | pages = 403–405 | date = November 1993 | pmid = 8291080 | doi = 10.1016/0968-0004(93)90132-7 }}</ref> Small changes of enzymatic activity are extremely common among enzymes. In particular, substrate binding specificity (see above) can easily and quickly change with single amino acid changes in their substrate binding pockets. This is frequently seen in the main enzyme classes such as [[kinase]]s.<ref>{{cite journal | vauthors = Ochoa D, Bradley D, Beltrao P | title = Evolution, dynamics and dysregulation of kinase signalling | journal = Current Opinion in Structural Biology | volume = 48 | pages = 133–140 | date = February 2018 | pmid = 29316484 | doi = 10.1016/j.sbi.2017.12.008 }}</ref>

Artificial (in vitro) evolution is now commonly used to modify enzyme activity or specificity for industrial applications (see below).