What is the active site (not metal binding site) of tyrosinase and other monooxygenase/oxidoreductases?
Tyrosinase uses two copper ions as cofactors. The copper binding site is the enzyme active site.



The active site of the crystal structure of tyrosinase from Streptomyces sp. (PDB code: 3AWT) is shown below. Note the two copper ions (coordinated by active site histidine amino acid residues) and an oxygen atom (of a water molecule) bound to the copper ions:




Matoba et al. (2011) J Biol Chem 34: 30219-30231.


  The Cu(II)-soaked crystal structure of tyrosinase ... possesses two
  copper ions at its catalytic center.