Has quercetin 2,3-dioxygenase activity in vitro. Its physiological role is unknown; however, may provide a mechanism that would avoid inhibition of key cellular proteins, such as DNA gyrase, by quercetin. O2 + quercetin = 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoate + CO Binds 1 divalent metal cation, Zn(2+), Co(2+) or Fe(2+). Inhibited by kojic acid, sodium diethyldithiocarbamate and 1,10-phenanthroline monohydrochloride. Flavonoid metabolism; quercetin degradation. Is composed of two structurally similar domains arranged face to face. Quercetin is a flavonoid compound synthesized by a variety of plants, including foods for human consumption. Belongs to the pirin family.