Cloned (Comment) | Organism |
---|---|
gene jrPPO1, DNA and amino acid sequence determination and analysis, sequence comparisons | Juglans regia |
Protein Variants | Comment | Organism |
---|---|---|
additional information | generation of a truncated enzyme comprisine residues 101-445 | Juglans regia |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
additional information | - |
additional information | MichaelisMenten kinetics | Juglans regia |
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 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 | 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 | UniProt | Comment | Textmining |
---|---|---|---|
Juglans regia | C0LU17 | leaves harvested from several trees in the surroundings of Vienna | - |
Posttranslational Modification | Comment | Organism |
---|---|---|
proteolytic modification | tyrosinase requires proteolytical activation | Juglans regia |
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 | Comment | Organism | Textmining |
---|---|---|---|
leaf | - |
Juglans regia | - |
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 | Comment | Organism |
---|---|---|
? | x * 39000, isozyme PPO1, SDS-PAGE | Juglans regia |
More | enzyme peptide sequencing by nanoUHPLCESI-MS/MS, sequence comparisons | Juglans regia |
Synonyms | Comment | Organism |
---|---|---|
jrPPO1 | - |
Juglans regia |
polyphenol oxidase | - |
Juglans regia |
PPO | - |
Juglans regia |
PPO1 | - |
Juglans regia |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
25 | - |
assay at | Juglans regia |
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 Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
5.4 | - |
diphenolase assay at | Juglans regia |
7 | - |
monophenolase assay at | Juglans regia |
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 | 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 |