Oxidoreductases;
Acting on paired donors, with incorporation or reduction of molecular oxygen;
With another compound as one donor, and incorporation of one atom of oxygen into the other donor
BRITE hierarchy

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;
(2) 2 L-dopa + O2 = 2 dopaquinone + 2 H2O [RN:R00045]

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

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.

EC 1.14.18.1 created 1972, modified 1976, modified 1980 (EC 1.14.17.2 created 1972, incorporated 1984), modified 2012