The third cupredoxin domain of the insect laccases similar to laccase 2 in Tribolium castaneum
This multicopper oxidase (MCO) family includes the majority of insect laccases. One member of the family is laccase 2 from Tribolium castaneum. Laccase 2 is required for beetle cuticle tanning. Laccase (polyphenol oxidase EC 1.10.3.2) is a blue multi-copper enzyme that catalyzes the oxidation of a variety of organic substrates coupled to the reduction of molecular oxygen to water. It displays broad substrate specificity, catalyzing the oxidation of a wide variety of aromatic - notably phenolic and inorganic substances. Laccase has been implicated in a wide spectrum of biological activities and, in particular, plays a key role in morphogenesis, development and lignin metabolism in fungi, plants and insects. Although MCOs have diverse functions, majority of them have three cupredoxin domain repeats 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 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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