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Literature summary for 1.14.18.1 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)

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

Protein Variants

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

KM Value [mM]

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

Metals/Ions

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

Molecular Weight [Da]

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

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
2 L-dopa + O2 Juglans regia
-
2 dopaquinone + 2 H2O
-
?
L-tyrosine + O2 Juglans regia
-
dopaquinone + H2O
-
?

Organism

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

Posttranslational Modification

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

Purification (Commentary)

Purification (Comment) Organism
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

Source Tissue Comment Organism Textmining
leaf
-
Juglans regia
-

Substrates and Products (Substrate)

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

Subunits

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

Synonyms

Synonyms Comment Organism
jrPPO1
-
Juglans regia
polyphenol oxidase
-
Juglans regia
PPO
-
Juglans regia
PPO1
-
Juglans regia

Temperature Optimum [°C]

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

Turnover Number [1/s]

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

pH Optimum

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

pI Value

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

General Information

General Information Comment Organism
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
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