Tyrosinase is a copper-containing metalloprotein belonging to the type-3 copper protein family, together with haemocyanins and catechol oxidases. Tyrosinases are the catalysts in mammals responsible for the formation of melanin in skin and hair color, as well as browning in fruit and vegetables following cell damage.
Tyrosinases are found in various prokaryotes as well as in plants, fungi, arthropods, and mammals and are responsible for pigmentation, wound healing, radiation protection, and primary immune response. Tyrosinases perform two sequential enzymatic reactions: hydroxylation of monophenols and oxidation of diphenols to form quinones which polymerize spontaneously to melanin. In plants, sponges, and many invertebrates, tyrosinases are important for wound healing and primary immune responses; in arthropods, they play a role in sclerotization, and in bacteria, tyrosinases protect DNA from UV damage.