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ENZYME

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 + O2 <=> H2O + L-dopaquinone
  • 2 L-dopa + O2 <=> 2 H2O + 2 L-dopaquinone
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
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
Rhea expert-curated reactions1.14.18.1
UniProtKB/Swiss-Prot
Q00024, PPO1_AGABIQ3ZPT5, PPO1_SPOLTO42713, PPO2_AGABI
Q9V521, PPO2_DROMEC7FF04, PPO3_AGABIQ8I1F6, PPO3_DROER
Q9W1V6, PPO3_DROMEC0HJM0, PPO3_SARARC7FF05, PPO4_AGABI
Q27451, PRP1_BOMMOO44249, PRP1_MANSEP85046, PRP1_SIMDA
Q27452, PRP2_BOMMOQ6UEH6, PRP2_GALMEQ25519, PRP2_MANSE
Q8J130, TYRO_ASPFUQ00234, TYRO_ASPORQ8MIU0, TYRO_BOVIN
P54834, TYRO_CANLFP55024, TYRO_CHICKQ08410, TYRO_COTJA
P55033, TYRO_FELCAQ9BDE0, TYRO_GORGOP14679, TYRO_HUMAN
P11344, TYRO_MOUSEP00440, TYRO_NEUCRP55025, TYRO_ORYLA
Q0MVP0, TYRO_PELLEQ04604, TYRO_PELNIP55026, TYRO_PELSI
A7BHQ9, TYRO_PHONAQ92396, TYRO_PODASP33180, TYRO_RHIML
P07524, TYRO_STRATP06845, TYRO_STRGAP55022, TYRO_STRGB
P55023, TYRO_STRLNB8NM74, USTQ_ASPFN

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