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Literature summary extracted from

  • Ramsden, C.A.; Riley, P.A.
    Tyrosinase the four oxidation states of the active site and their relevance to enzymatic activation, oxidation and inactivation (2014), Bioorg. Med. Chem., 22, 2388-2395 .
    View publication on PubMed

Crystallization (Commentary)

EC Number Crystallization (Comment) Organism
1.14.18.1 crystal structure analysis Agaricus bisporus

Inhibitors

EC Number Inhibitors Comment Organism Structure
1.14.18.1 additional information the enzyme exhibits a lag period when employed in vitro and it is slowly inactivated by catechol substrates and is rapidly inactivated by resorcinols Agaricus bisporus
1.14.18.1 tropolone
-
 Agaricus bisporus

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
1.14.18.1 additional information
-
 additional information kinetics measurement and simulation of in vitro kinetics of the tyrosinase reaction Agaricus bisporus

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
1.14.18.1 Cu2+ binding of dioxygen to the two copper atoms (usually identified as CuA and CuB) located in the active site, inuclear copper-binding site of Agaricus bisporus tyrosinase, overview Agaricus bisporus

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
1.14.18.1 2 L-dopa + O2 Agaricus bisporus
-
 2 dopaquinone + 2 H2O
-
 ?
1.14.18.1 additional information Agaricus bisporus tyrosinase exhibits two mechanisms of oxidation: monooxygenase (EC 1.14.18.1) and oxidase (1.10.3.1) activities. The enzyme is characterised by possessing four discrete oxidation states (deoxy-, oxy-, met- and deact-tyrosinase), detailed overview. The enzyme exhibits a lag period when employed in vitro and it is slowly inactivated by catechol substrates and is rapidly inactivated by resorcinols ?
-
 ?
1.14.18.1 tyrosine + O2 Agaricus bisporus
-
 dopaquinone + H2O
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
1.14.18.1 Agaricus bisporus
-
-
-

Source Tissue

EC Number Source Tissue Comment Organism Textmining
1.14.18.1 commercial preparation
-
 Agaricus bisporus
-

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
1.14.18.1 2 L-dopa + O2
-
 Agaricus bisporus 2 dopaquinone + 2 H2O
-
 ?
1.14.18.1 additional information tyrosinase exhibits two mechanisms of oxidation: monooxygenase (EC 1.14.18.1) and oxidase (1.10.3.1) activities. The enzyme is characterised by possessing four discrete oxidation states (deoxy-, oxy-, met- and deact-tyrosinase), detailed overview. The enzyme exhibits a lag period when employed in vitro and it is slowly inactivated by catechol substrates and is rapidly inactivated by resorcinols Agaricus bisporus ?
-
 ?
1.14.18.1 additional information monooxygenation of L-tyrosine gives dopaquinone which undergoes rapid intramolecular cyclization giving cyclodopa. Spontaneous redox exchange with dopaquinone then gives 3,4-dihydroxyphenylalanine (dopa) and dopachrome. Thus, small amounts of monooxygenase activity, initially present, generate dopa from L-tyrosine and this activates more of the met-enzyme. N,N-Dimethyltyramine is oxidized to the corresponding ortho-quinone and undergoes cyclization but is unable to take part in redox exchange, and consequently no activating catechol is formed Rearrangement to a quinomethane prevents formation of an enzymeactivating catechol Agaricus bisporus ?
-
 ?
1.14.18.1 tyrosine + O2
-
 Agaricus bisporus dopaquinone + H2O
-
 ?

Subunits

EC Number Subunits Comment Organism
1.14.18.1 tetramer
-
 Agaricus bisporus

Synonyms

EC Number Synonyms Comment Organism
1.14.18.1 mushroom tyrosinase
-
 Agaricus bisporus

General Information

EC Number General Information Comment Organism
1.14.18.1 evolution tyrosinases are widespread in nature and act on a range of substrates Agaricus bisporus
1.14.18.1 metabolism the enzyme is involved in the melanin biosynthesis, pathway overview Agaricus bisporus
1.14.18.1 additional information the inter-relationship of the four discrete oxidation states of tyrosinase, i.e. oxy, deoxy, met, and deact, detailed overview. Native tyrosinase occurs mainly as met-tyrosinase in which a hydroxyl ion is bound to the two copper ions. Phenols bind to met-tyrosinase but are not oxidised by this form of the enzyme. Catechols, however, are oxidised by met-tyrosinase which in the process is reduced to deoxy-tyrosinase in which both coppers are now in the Cu(I) oxidation state. Deoxy-tyrosinase rapidly binds dioxygen to give oxy-tyrosinase in which the two oxygen atoms are held between the copper ions in the active site. Oxy-tyrosinase is the primary oxidising form of the enzyme and oxidises phenols by a monooxygenase mechanism and oxidises catechols by an oxidase mechanism. Thus, in the presence of dioxygen both phenols and catechols are oxidised by oxy-tyrosinase to ortho-quinones by quite separate oxidative cycles. During the catecholic cycle a catechol is occasionally treated as a phenol and oxidised by oxy-tyrosinase by a monooxygenase mechanism leading to the irreversible formation of deact-tyrosinase in which one of the copper atoms is reduced to the Cu(0) state and may diffuse out of the active centre. This minor pathway eventually leads to total inactivation of the enzyme by catechols. Oxy- to deact-tyrosinase conversion is inactivated by catechols and resorcinols Agaricus bisporus
1.14.18.1 physiological function tyrosinases are enzymes that exhibit both monooxygenase and oxidase activity and both activities arise from the binding of dioxygen to the two copper atoms (usually identified as CuA and CuB) located in the active site Agaricus bisporus