The third cupredoxin domain of Bilirubin oxidase (BOD)
Bilirubin oxidase (BOD) catalyzes the oxidation of bilirubin to biliverdin and the four-electron reduction of molecular oxygen to water. It is used in diagnosing jaundice through the determination of bilirubin in serum. BOD is a member of the multicopper oxidase (MCO) family that also includes laccase, ascorbate oxidase and ceruloplasmin. MCOs are capable of oxidizing a vast range of substrates, varying from aromatic compounds to inorganic compounds such as metals. Although the members of this family have diverse functions, majority of them have three cupredoxin domain repeats. The copper ions are bound in several sites: Type 1, Type 2, and/or Type 3. The ensemble of types 2 and 3 copper is called a trinuclear cluster. MCOs oxidize their substrate by accepting electrons at a mononuclear copper center and transferring them to the active site trinuclear copper center. The cupredoxin domain 3 of 3-domain MCOs contains the Type 1 (T1) copper binding site and part the trinuclear copper binding site, which is located at the interface of domains 1 and 3.
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