# Chelatase

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Chelatase
> Markdown URL: https://mediated.wiki/source/Chelatase.md
> Source: https://en.wikipedia.org/wiki/Chelatase
> Source revision: 1301495347
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{Short description|Class of enzymes}}
In [biochemistry](/source/biochemistry), '''chelatases''' are [enzyme](/source/enzyme)s that catalyze the insertion ("[metalation](/source/metalation)") of naturally occurring [tetrapyrrole](/source/tetrapyrrole)s. Many tetrapyrrole-based [cofactors](/source/Cofactor_(biochemistry)) exist in nature including [heme](/source/heme)s, [chlorophyll](/source/chlorophyll)s, and [vitamin B12](/source/vitamin_B12). These metallo cofactors are derived by the reaction of metal cations with tetrapyrroles, which are not [ligand](/source/ligand)s ''per se'', but the conjugate acids thereof. In the case of [ferrochelatase](/source/ferrochelatase)s, the reaction that chelatases catalyze is:<ref>{{cite encyclopedia|chapter=Tetrapyrroles in Plants: Chemical Biology of Metal Insertion and Removal |author1=Kaushik Saha |author2=Michaël Moulin |author3=Alison G. Smith |title=Wiley Encyclopedia of Chemical Biology |year=2009 |publisher=John Wiley & Sons |encyclopedia=Encyclopedia of Chemical Biology |pages=1–13 |isbn=978-0470048672 |doi=10.1002/9780470048672.wecb454}}</ref>
:Fe<sup>2+</sup>  +  H<sub>2</sub>P  →  FeP  +  2 H<sup>+</sup>
In the above equation H<sub>2</sub>P represents a [sirohydrochlorin](/source/sirohydrochlorin) or a porphyrin, such as [protoporphyrin IX](/source/protoporphyrin_IX).

[[Image:Protoporphyrin IX.svg|thumb|right|[Protoporphyrin IX](/source/Protoporphyrin_IX) features a rigid 18-membered ring, with a N4 cavity occupied with two protons. The displacement of those protons and insertion of a metal cation requires the presence of chelatases.]]
Chelatases are required because porphyrins and related [macrocyclic ligand](/source/macrocyclic_ligand)s are extremely slow to metalate, despite favorable thermodynamics. These low rates are attributed to the tight fit of the metal into the rigid 18- or 17-membered tetrapyrrole macrocycle. Several families of chelatase are known including [cobalt chelatase](/source/cobalt_chelatase), [magnesium chelatase](/source/magnesium_chelatase), and [ferrochelatase](/source/ferrochelatase). Nickel insertion into a [sirohydrochlorin](/source/sirohydrochlorin) also requires a chelatase as part of the biosynthesis of [cofactor F430](/source/cofactor_F430). Apparently that chelatase is identical to the cobalt chelatase.<ref>{{Cite journal|last1=Moore|first1=Simon J. |last2=Sowa|first2=Sven T. |last3=Schuchardt |first3=Christopher |last4=Deery |first4=Evelyne |last5=Lawrence |first5=Andrew D. |last6=Ramos |first6=José Vazquez |last7=Billig |first7=Susan |last8=Birkemeyer |first8=Claudia |last9=Chivers |first9=Peter T. |date=2017-03-02 |title=Elucidation of the biosynthesis of the methane catalyst coenzyme F430 |journal=Nature |language=en |volume=543 |issue=7643 |pages=78–82 |doi=10.1038/nature21427 |pmid=28225763 |pmc=5337119 |issn=0028-0836}}</ref>

==References==
{{reflist}}

{{Enzymes}}

Category:Ligases
Category:Organometallic chemistry

---
Adapted from the Wikipedia article [Chelatase](https://en.wikipedia.org/wiki/Chelatase) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Chelatase?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.