This is the C-terminal domain of Tyosinase present in Aspergillus oryzae. Tyosinase is a dinuclear copper monooxygenase/oxidase that plays a crucial role in the melanin pigment biosynthesis. The C-terminal domain is referred to as the shielding domain as it prohibits substrate access to the enzyme-active site and blocks the oxidase/oxygenase activity to avoid undesirable intracellular reactions of highly reactive quinonoid products. This means the domain may play an important role in regulating the enzyme activity. Two of the three cysteines (Cys522, and Cys525) that play a significant role in the copper incorporation process belong to the C-terminal domain [1].

1: Crystal structures of copper-depleted and copper-bound fungal pro-tyrosinase: insights into endogenous cysteine-dependent copper incorporation. Fujieda N, Yabuta S, Ikeda T, Oyama T, Muraki N, Kurisu G, Itoh S; J Biol Chem. 2013;288:22128-22140. PMID:23749993