tyrosinase;
monophenol monooxygenase;
phenolase;
monophenol oxidase;
cresolase;
monophenolase;
tyrosine-dopa oxidase;
monophenol monooxidase;
monophenol dihydroxyphenylalanine:oxygen oxidoreductase;
N-acetyl-6-hydroxytryptophan oxidase;
monophenol, dihydroxy-L-phenylalanine oxygen oxidoreductase;
o-diphenol:O2 oxidoreductase;
phenol oxidase

Oxidoreductases;
Acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2;
With another compound as one donor, and incorporation of one atom of oxygen into the other donor

L-tyrosine,L-dopa:oxygen oxidoreductase

(1) L-tyrosine + O2 = dopaquinone + H2O (overall reaction);
(1a) L-tyrosine + 1/2 O2 = L-dopa [RN:R00031];
(1b) L-dopa + 1/2 O2 = dopaquinone + H2O [RN:R00045];
(2) 2 L-dopa + O2 = 2 dopaquinone + 2 H2O

R00031 R00045;
(other) R00058 R00731 R02078 R02363 R02383 R02950 R04693 R04884

L-tyrosine [CPD:C00082];
O2 [CPD:C00007];
L-dopa [CPD:C00355]

A type III copper protein found in a broad variety of bacteria, fungi, plants, insects, crustaceans, and mammals, which is involved in the synthesis of betalains and melanin. The enzyme, which is activated upon binding molecular oxygen, can catalyse both a monophenolase reaction cycle (reaction 1) or a diphenolase reaction cycle (reaction 2). During the monophenolase cycle, one of the bound oxygen atoms is transferred to a monophenol (such as L-tyrosine), generating an o-diphenol intermediate, which is subsequently oxidized to an o-quinone and released, along with a water molecule. The enzyme remains in an inactive deoxy state, and is restored to the active oxy state by the binding of a new oxygen molecule. During the diphenolase cycle the enzyme binds an external diphenol molecule (such as L-dopa) and oxidizes it to an o-quinone that is released along with a water molecule, leaving the enzyme in the intermediate met state. The enzyme then binds a second diphenol molecule and repeats the process, ending in a deoxy state [7].
The second reaction is identical to that catalysed by the related enzyme catechol oxidase (EC 1.10.3.1). However, the latter can not catalyse the hydroxylation or monooxygenation of monophenols.

1

Dawson, C.R. and Tarpley, W.B.

The copper oxidases.

In: Sumner, J.B. and Myrback, K. (Eds.), The Enzymes, 1st ed., vol. 2, Academic Press, New York, 1951, p. 454-498.

2  [PMID:5842066]

Patil SS, Zucker M.

Potato phenolases. Purification and properties.

J. Biol. Chem. 240 (1965) 3938-43.

Solanum tuberosum

3  [PMID:13972077]

POMERANTZ SH.

Separation, purification, and properties of two tyrosinases from hamster melanoma.

J. Biol. Chem. 238 (1963) 2351-7.

hamster

4  [PMID:13972077]

POMERANTZ SH.

Separation, purification, and properties of two tyrosinases from hamster melanoma.

J. Biol. Chem. 238 (1963) 2351-7.

hamster

5

Robb, D.A.

`Tyrosinase.

In: Lontie, R. (Ed.), Copper Proteins and Copper Enzymes, vol. 2, CRC Press, Boca Raton, FL, 1984, p. 207-240.

6

Robb, D.A.

`Tyrosinase.

In: Lontie, R. (Ed.), Copper Proteins and Copper Enzymes, vol. 2, CRC Press, Boca Raton, FL, 1984, p. 207-240.

7  [PMID:7873577]

Sanchez-Ferrer A, Rodriguez-Lopez JN, Garcia-Canovas F, Garcia-Carmona F

Tyrosinase: a comprehensive review of its mechanism.

Biochim. Biophys. Acta. 1247 (1995) 1-11.

8  [PMID:7873577]

Sanchez-Ferrer A, Rodriguez-Lopez JN, Garcia-Canovas F, Garcia-Carmona F

Tyrosinase: a comprehensive review of its mechanism.

Biochim. Biophys. Acta. 1247 (1995) 1-11.

9  [PMID:8660589]

Steiner U, Schliemann W, Strack D

Assay for tyrosine hydroxylation activity of tyrosinase from betalain-forming plants and cell cultures.

Anal. Biochem. 238 (1996) 72-5.

10 [PMID:8660589]

Steiner U, Schliemann W, Strack D

Assay for tyrosine hydroxylation activity of tyrosinase from betalain-forming plants and cell cultures.

Anal. Biochem. 238 (1996) 72-5.

11 [PMID:21416076]

Rolff M, Schottenheim J, Decker H, Tuczek F

Copper-O2 reactivity of tyrosinase models towards external monophenolic substrates: molecular mechanism and comparison with the enzyme.

Chem. Soc. Rev. 40 (2011) 4077-98.

12 [PMID:21416076]

Rolff M, Schottenheim J, Decker H, Tuczek F

Copper-O2 reactivity of tyrosinase models towards external monophenolic substrates: molecular mechanism and comparison with the enzyme.

Chem. Soc. Rev. 40 (2011) 4077-98.