Tyrosinase

Literature References: A copper-containing enzyme widely distributed in plants, animals, and man. Catalyzes the hydroxylation of tyrosine in the liver and in melanin-forming cells to 3,4-dihydroxyphenylalanine (dopa). Causes the cut surface of many fruits and plants to darken. The enzyme, as isolated from the common edible mushroom or potato, is characterized by its ability to catalyze aerobic oxidation of both monohydric and o-dihydric phenols. These activities are commonly referred to as cresolase (monophenolase, monophenoloxidase) and catecholase (o-dihydric phenolase) activities. Since monophenolase activity is frequently lost during purification of the enzyme, the name polyphenolase (polyphenoloxidase) is preferred by some workers for prepns which have mainly o-dihydric phenolase activity. Ref: C. R. Dawson, W. B. Tarpley "Copper Oxidases" in J. B. Sumner, K. Myrbäck, The Enzymes vol. II, (Academic Press, New York, 1951) pp 456-483. Prepn from potato peels: Kubowitz, Biochem. Z. 299, 32 (1938). Extraction from mushrooms: Cohen, Lerner, US 2956929 (1960 to Gillette). Separation of a-, b-, g-, and d-tyrosinases of mushroom tyrosinase: Bouchilloux et al., J. Biol. Chem. 238, 1699 (1963). Isoln and properties of crystalline tyrosinase from Neurospora: Fling et al., ibid., p 2045. Isoln and properties of b-tyrosinase: Kumagai et al., J. Biol. Chem. 245, 1767 (1970).