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ENZYME entry: EC 1.14.18.1

Accepted Name
Tyrosinase.
Alternative Name(s)
Cresolase.
Monophenol monooxygenase.
Monophenol oxidase.
N-acetyl-6-hydroxytryptophan oxidase.
Phenolase.
Tyrosine-dopa oxidase.
Reaction catalysed
  • L-tyrosine + O(2) <=> dopaquinone + H(2)O
  • 2 L-dopa + O(2) <=> 2 dopaquinone + 2 H(2)O
Cofactor(s)
Cu cation.
Comment(s)
  • 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 catalyze both a monophenolase reaction cycle or a diphenolase reaction cycle.
  • 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.
  • The second reaction is identical to that catalyzed by the related enzyme catechol oxidase (EC 1.10.3.1).
  • However, the latter can not catalyze the hydroxylation or monooxygenation of monophenols.
  • Formerly EC 1.14.17.2.
Cross-references
PROSITEPDOC00398
BRENDA1.14.18.1
EC2PDB1.14.18.1
ExplorEnz1.14.18.1
PRIAM enzyme-specific profiles1.14.18.1
KEGG Ligand Database for Enzyme Nomenclature1.14.18.1
IUBMB Enzyme Nomenclature1.14.18.1
IntEnz1.14.18.1
MEDLINEFind literature relating to 1.14.18.1
MetaCyc1.14.18.1
UniProtKB/Swiss-Prot
Q00024, PPO1_AGABI;  O42713, PPO2_AGABI;  Q9V521, PPO2_DROME;  
C7FF04, PPO3_AGABI;  Q8I1F6, PPO3_DROER;  Q9W1V6, PPO3_DROME;  
C0HJM0, PPO3_SARAR;  C7FF05, PPO4_AGABI;  Q27451, PRP1_BOMMO;  
O44249, PRP1_MANSE;  P85046, PRP1_SIMDA;  Q27452, PRP2_BOMMO;  
Q25519, PRP2_MANSE;  Q8J130, TYRO_ASPFU;  Q00234, TYRO_ASPOR;  
Q8MIU0, TYRO_BOVIN;  P54834, TYRO_CANLF;  P55024, TYRO_CHICK;  
Q08410, TYRO_COTJA;  P55033, TYRO_FELCA;  Q9BDE0, TYRO_GORGO;  
P14679, TYRO_HUMAN;  P11344, TYRO_MOUSE;  P00440, TYRO_NEUCR;  
P55025, TYRO_ORYLA;  Q0MVP0, TYRO_PELES;  Q04604, TYRO_PELNI;  
P55026, TYRO_PELSI;  A7BHQ9, TYRO_PHONA;  Q92396, TYRO_PODAS;  
P33180, TYRO_RHIML;  P07524, TYRO_STRAT;  P06845, TYRO_STRGA;  
P55022, TYRO_STRGB;  P55023, TYRO_STRLN;  B8NM74, USTQ_ASPFN;  

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