Pseudoperoxidase activity of mushroom tyrosinase

Under anaerobic conditions, ethyl hydroperoxide functions as a two-electron acceptor in the tyrosinase-catalyzed oxidation of 4-tert-butylcatechol to 4-tert-butyl-o-benzoquinone, apparently by the following mechanism:

$\text{T?Cu(II)]}{}_2\text{+ TBC = T?Cu(I)]}{}_2\text{+ TB?}\text{o?}\text{BQ + 2H}{}^{\mathrm{+}}$

$\text{T?Cu(I)]}{}_2\text{+ EtOOH + 2H}{}^{\mathrm{+}}\text{= T?Cu(II)]}{}_2\text{+ EtOH +H}{}^2\text{O}$

This is a direct demonstration of the pseudoperoxidase activity of tyrosinase. Ethyl hydroperoxide failed to oxidize either oxy- or deoxyhemocyanin.