3-hydroxy-4-oxoquinoline 2,4-dioxygenase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are 3-hydroxyquinolin-4(1H)-one and oxygen. Its products are N-formylanthranilic acid and carbon monoxide.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O<sub>2</sub> as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O<sub>2</sub>. The systematic name of this enzyme class is 3-hydroxy-1H-quinolin-4-one 2,4-dioxygenase (CO-forming). Other names in common use include (1H)-3-hydroxy-4-oxoquinoline 2,4-dioxygenase, 3-hydroxy-4-oxo-1,4-dihydroquinoline 2,4-dioxygenase, 3-hydroxy-4(1H)-one, 2,4-dioxygenase, and quinoline-3,4-diol 2,4-dioxygenase.