Cupredoxin domain 2 of Copper-containing nitrite reductase
Copper-containing nitrite reductase (CuNIR), which catalyzes the reduction of NO2- to NO, is the key enzyme in the denitrification process in denitrifying bacteria. CuNIR contains at least one type 1 copper center and a type 2 copper center in the protein. The type 2 copper center of a copper nitrite reductase is the active site of the enzyme. A histidine, bound to the Type 2 Cu center, is responsible for binding and reducing nitrite. A Cys-His bridge plays an important role in facilitating rapid electron transfer from the type 1 center to the type 2 center. A reduced type I blue copper protein (pseudoazurin) was found to be a specific electron transfer donor for the copper-containing NIR in bacteria Alcaligenes faecalis.
Jiyao W et al.(2023). "The conserved domain database in 2023.",