The third cupredoxin domain of the bacterial laccases similar to Tth-MCO from Thermus Thermophilus
The subfamily of bacterial laccases includes Tth-MCO and similar proteins. Tth-MCO is a hyperthermophilic multicopper oxidase (MCO) from thermus thermophilus HB27. Laccase is a blue multi-copper enzyme that catalyzes the oxidation of a variety aromatic - notably phenolic and inorganic substances coupled to the reduction of molecular oxygen to water. It 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 and plants. 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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