Tyrosinase

Tyrosinase is an enzyme that is involved in the production of melanin and other pigments from tyrosine by oxidation. It is found in a wide variety of organisms, including humans, animals, plants, and fungi. Tyrosinase is a copper-containing enzyme that catalyzes several reactions in the melanin synthesis pathway.

Function

Tyrosinase carries out the oxidation of phenols such as tyrosine and dopamine using dioxygen (O2). In humans, tyrosinase is sorted into melanosomes and the catalytically active domain of the protein resides within melanosomes. Only a small, enzymatically inessential part of the protein extends into the cytoplasm of the melanocyte.

Clinical significance

Mutations in the tyrosinase gene result in oculocutaneous albinism type 1 (OCA1), a disorder characterized by a reduction or complete loss of melanin pigment in the skin, hair, and eyes. OCA1 is the most severe type of albinism and is the most common form worldwide.

Structure

The three-dimensional structure of tyrosinase reveals that the protein is a dimer, with each monomer containing a binuclear, type 3 copper centre. The copper ions are coordinated by six histidine residues in the active site.

See also

• Melanin
• Oculocutaneous albinism
• Tyrosine

References

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