The second cupredoxin domain of uncharacterized multicopper oxidase
Multicopper Oxidases (MCOs) are multi-domain enzymes that are able to couple oxidation of substrates with reduction of dioxygen to water. MCOs oxidise their substrate by accepting electrons at a mononuclear copper centre and transferring them to a trinuclear copper centre which binds a dioxygen. The dioxygen, following the transfer of four electrons, is reduced to two molecules of water. These MCOs are capable of oxidizing a vast range of substrates, varying from aromatic to inorganic compounds such as metals. This family of MCOs is composed of three cupredoxin domains that include one mononuclear and one trinuclear copper center. 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 2 of 3-domain MCOs has lost the ability to bind copper.