Catechol oxidase is a copperoxidase that contains a type 3 di-copper cofactor and catalyzes the oxidation of ortho-diphenols into ortho-quinones coupled with the reduction of molecular oxygen to water. It is present in a variety of species of plants and fungi including Ipomoea batatas (sweet potato)[1] and Camellia sinensis (Indian tea leaf).[2] Metalloenzymes with type 3 copper centers are characterized by their ability to reversibly bind dioxygen at ambient conditions.[3] In plants, catechol oxidase plays a key role in enzymatic browning by catalyzing the oxidation of catechol to o-quinone in the presence of oxygen, which can rapidly polymerize to form the melanin that grants damaged fruits their dark brown coloration.
^Gerdemann C, Eicken C, Krebs B (March 2002). "The crystal structure of catechol oxidase: new insight into the function of type-3 copper proteins". Accounts of Chemical Research. 35 (3): 183–91. doi:10.1021/ar990019a. PMID11900522.
^Halder J, Tamuli P, Bhaduri A (1998). "Isolation and characterization of polyphenol oxidase from Indian tea leaf (Camellia sinensis)". The Journal of Nutritional Biochemistry. 9 (2): 75–80. doi:10.1016/s0955-2863(97)00170-8.
^Koval IA, Gamez P, Belle C, Selmeczi K, Reedijk J (September 2006). "Synthetic models of the active site of catechol oxidase: mechanistic studies". Chemical Society Reviews. 35 (9): 814–40. doi:10.1039/b516250p. PMID16936929.