InterPro: IPR002227 Tyrosinase

Tyrosinase (EC:1.14.18.1) [1] is a copper monooxygenases that catalyzes the hydroxylation of monophenols and the oxidation of o-diphenols to o-quinols. This enzyme, found in prokaryotes as well as in eukaryotes, is involved in the formation of pigments such as melanins and other polyphenolic compounds. Tyrosinase binds two copper ions (CuA and CuB). Each of the two copper ions has been shown [2] to be bound by three conserved histidines residues. The regions around these copper-binding ligands are well conserved and also shared by some hemocyanins, which are copper-containing oxygen carriers from the hemolymph of many molluscs and arthropods [3, 4]. At least two proteins related to tyrosinase are known to exist in mammals, and include TRP-1 (TYRP1) [5], which is responsible for the conversion of 5,6-dihydro-xyindole-2-carboxylic acid (DHICA) to indole-5,6-quinone-2-carboxylic acid; and TRP-2 (TYRP2) [6], which is the melanogenic enzyme DOPAchrome tautomerase (EC:5.3.3.12) that catalyzes the conversion of DOPAchrome to DHICA. TRP-2 differs from tyrosinases and TRP-1 in that it binds two zinc ions instead of copper [7]. Other proteins that belong to this family are plant polyphenol oxidases (PPO) (EC:1.10.3.1), which catalyze the oxidation of mono- and o-diphenols to o-diquinones [8]; and Caenorhabditis elegans hypothetical protein C02C2.1.