May be involved in a redox system involving ascorbic acid. 4 L-ascorbate + O2 = 2 H2O + 4 monodehydro-L-ascorbate radical Binds 4 Cu cations per monomer. The Cu cations are bound as 3 distinct Cu centers known as type 1 or blue, type 2 or normal, and type 3 or coupled binuclear. Dimer. Belongs to the multicopper oxidase family.