Chloridazon catechol dioxygenase

Chloridazon-catechol dioxygenase (EC 1.13.11.36) is an enzyme that catalyzes the chemical reaction

5-amino-4-chloro-2-(2,3-dihydroxyphenyl)-3(2H)-pyridazinone + O₂ ⇌ 5-amino-4-chloro-2-(2-hydroxymuconoyl)-3(2H)-pyridazinone

Thus, the two substrates of this enzyme are 5-amino-4-chloro-2-(2,3-dihydroxyphenyl)-3(2H)-pyridazinone and oxygen, whereas its product is 5-amino-4-chloro-2-(2-hydroxymuconoyl)-3(2H)-pyridazinone.

This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O₂ as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O₂. The systematic name of this enzyme class is 5-amino-4-chloro-2-(2,3-dihydroxyphenyl)-3(2H)-pyridazinone 1,2-oxidoreductase (decyclizing). It employs one cofactor, iron.