It is known that tyrosinase is an enzyme responsible for melanin production and has two metal ions(copper ions or zinc ions) in its active site. In this study, we performed an FMO calculation with FMO2-MP2/6-31G revel for tyrosinase-tyrosine complex and computed the inter-fragment interaction energies (IFIEs) among tyrosine, zinc ions, water molecule, and the amino acid residues in tyrosinase. We aim to obtain detailed knowledge on the enzymatic reaction mechanism of tyrosinase through the IFIE analysis. The FMO computations show that tyrosine binds to tyrosinase via two zinc ions. We also found that the water molecule strongly binds to tyrosinase via two zinc ions. These results show that two zinc ions and water molecule are considered to play an important role in the oxidation reaction of tyrosine.
