Crystal structure of the copper-containing quercetin 2,3-dioxygenase from Aspergillus japonicus

Summary nonblue copper oxidases, and Cu,Zn superoxide dismu- tase. The most common ligand in type 2 copper sites Quercetin 2,3-dioxygenase is a copper-containing en- zyme that catalyzes the insertion of molecular oxygen is histidine. The stereochemical requirements are less critical in type 2 copper centers than in type 1, allowing into polyphenolic flavonols. Dioxygenation catalyzed by iron-containing enzymes has been studied extensively, for a larger array of coordination geometries. The type 3 copper, present in hemocyanin and tyrosinase, is mostly but dioxygenases employing other metal cofactors are poorly understood. We determined the crystal struc- associated with redox reactions. It consists of a pair of Cu 2 ions and is characterized by a strong absorption ture of quercetin 2,3-dioxygenase at 1.6 A u resolution. The enzyme forms homodimers, which are stabilized band at 300 nm. The reactivity of the copper centers in