Tyrosinase is a copper-containing o, Xenopus/Amphibian,idase that functions in the formation of pigments such as melanins and other polyphenolic compounds. Tyrosinase catalyzes the rate-limiting conversions of tyrosine to DOPA, DOPA to DOPA-quinone and 5,6-dihydro, Xenopus/Amphibian,yindole to indole-5,6 quinone. Defects in TYR are the cause of albinism oculocutaneous type 1A (OCA1A), also known as tyrosinase negative oculocutaneous albinism. OCA1A an autosomal recessive disorder in which the biosynthesis of melanin pigment is absent in skin, hair, and eyes.