Differentiation of Fungal Tyrosinases and Laccases Using Selective Inhibitors and Substrates

Fungal tyrosinases and laccases can utilize similar substrates and can be difficult to differentiate. In Agaricus bisporus, both enzymes can use dopa, p-cresol, and diaminobenzidine as substrates, albeit at different rates. Tolidine can be used as a selective substrate to differentiate Agaricus laccase from Agaricus tyrosinase. Oxidation of this substrate, however, did not appear to be inhibited by cetyltrimethylammonium bromide, a common laccase inhibitor. N-hydroxylglycine appeared to be a selective inhibitor of laccase since it did not inhibit tyrosinase activity. Tropolone, salicylhydroxamic acid, and 4-hexylresorcinol were more effective inhibitors of tyrosinase at low concentrations than cinnamic acid or 2,3-naphthalenediol. Similar patterns of substrate and inhibitor preferences were noted in other mushroom species such as Oyster, Enoki, and Shiitake mushrooms.