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Literature summary extracted from

  • Zekiri, F.; Molitor, C.; Mauracher, S.G.; Michael, C.; Mayer, R.L.; Gerner, C.; Rompel, A.
    Purification and characterization of tyrosinase from walnut leaves (Juglans regia) (2014), Phytochemistry, 101, 5-15 .
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

EC Number Cloned (Comment) Organism
1.14.18.1 gene jrPPO1, DNA and amino acid sequence determination and analysis, sequence comparisons Juglans regia

Protein Variants

EC Number Protein Variants Comment Organism
1.14.18.1 additional information generation of a truncated enzyme comprisine residues 101-445 Juglans regia

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
1.14.18.1 additional information
-
 additional information Michaelis–Menten kinetics Juglans regia

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
1.14.18.1 Cu2+ a type-3 copper enzyme containing two copper ions, each coordinated by three histidine residues Juglans regia

Molecular Weight [Da]

EC Number Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
1.14.18.1 38890
-
 truncated enzyme form 2, comprising residues 101-445, HPLC/mass spectrometry Juglans regia
1.14.18.1 39047
-
 truncated enzyme form 1, comprising residues 101-445, HPLC/mass spectrometry Juglans regia

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 Juglans regia
-
 2 dopaquinone + 2 H2O
-
 ?
1.14.18.1 L-tyrosine + O2 Juglans regia
-
 dopaquinone + H2O
-
 ?

Organism

EC Number Organism UniProt Comment Textmining
1.14.18.1 Juglans regia C0LU17 leaves harvested from several trees in the surroundings of Vienna
-

Posttranslational Modification

EC Number Posttranslational Modification Comment Organism
1.14.18.1 proteolytic modification tyrosinase requires proteolytical activation Juglans regia

Purification (Commentary)

EC Number Purification (Comment) Organism
1.14.18.1 native enzyme from leaves by aqueous two-phase extraction method followed by cation exchange chromatography, ultrafiltration, and anion exchange chromatography, isolation of two forms of isozyme PPO1 Juglans regia

Source Tissue

EC Number Source Tissue Comment Organism Textmining
1.14.18.1 leaf
-
 Juglans regia
-

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
1.14.18.1 2 L-dopa + O2
-
 Juglans regia 2 dopaquinone + 2 H2O
-
 ?
1.14.18.1 4-tert-butylcatechol + O2
-
 Juglans regia ?
-
 ?
1.14.18.1 L-tyrosine + O2
-
 Juglans regia dopaquinone + H2O
-
 ?
1.14.18.1 additional information the purified native enzyme shows a rather high monophenolase activity compared to diphenolase activity Juglans regia ?
-
 ?

Subunits

EC Number Subunits Comment Organism
1.14.18.1 ? x * 39000, isozyme PPO1, SDS-PAGE Juglans regia
1.14.18.1 More enzyme peptide sequencing by nanoUHPLC–ESI-MS/MS, sequence comparisons Juglans regia

Synonyms

EC Number Synonyms Comment Organism
1.14.18.1 jrPPO1
-
 Juglans regia
1.14.18.1 polyphenol oxidase
-
 Juglans regia
1.14.18.1 PPO
-
 Juglans regia
1.14.18.1 PPO1
-
 Juglans regia

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
1.14.18.1 25
-
 assay at Juglans regia

Turnover Number [1/s]

EC Number Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
1.14.18.1 20.8
-
 L-tyrosine pH 7.0, 25°C Juglans regia
1.14.18.1 199.3
-
 L-Dopa pH 7.0, 25°C Juglans regia

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
1.14.18.1 5.4
-
 diphenolase assay at Juglans regia
1.14.18.1 7
-
 monophenolase assay at Juglans regia

pI Value

EC Number Organism Comment pI Value Maximum pI Value
1.14.18.1 Juglans regia form 1 of isozyme PPO1, isoelectric focussing
-
 5.1
1.14.18.1 Juglans regia form 2 of isozyme PPO1, isoelectric focussing
-
 5.2

General Information

EC Number General Information Comment Organism
1.14.18.1 additional information during the catalytic reaction, the type-3 copper center of tyrosinase exists in three different states. The reduced deoxy state [Cu(I)-Cu(I)] binds molecular oxygen and results in the oxy state [Cu(II)-O2 2-Cu(II)]. In the oxy state, peroxide is bound in a l-g2:g2 bridging mode. The met state [Cu(II)-Cu(II)] is assumed as the resting state of the copper site, where Cu(II) ions are bridged by a water molecule or hydroxyl ion. After addition of two equivalents H2O2 the full oxy form of the tyrosinase is developed Juglans regia
1.14.18.1 physiological function polyphenol oxidase (PPO) is a type-3 copper enzyme catalyzing the oxidation of phenolic compounds to their quinone derivates, which are further converted to melanin, a ubiquitous pigment in living organisms Juglans regia