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Literature summary for 1.10.3.1 extracted from
- The conformational state of polyphenol oxidase from field bean (Dolichos lablab) upon SDS and acid-pH activation (2006), Biochem. J., 395, 551-562.
Activating Compound
| Activating Compound | Comment | Organism | Structure |
|---|---|---|---|
| additional information | the enzyme is activated on exposure to acid-pH, activation at pH 2.5 and at pH 4.0, reversal of the activation is possible at pH 7.0, the activation by SDS and acidic pH results in a localized conformational change that is anchored around the catalytic site of PPO that alters the microenvironment of an essential glutamic residue, concentration or on exposure to acid-pH, the enzymes possesses a core carboxylate essential to activity, this enhanced catalytic efficiency of PPO, overview | Lablab purpureus | |
| SDS | severalfold activation at concentration below the critical micellar concentration of the enzyme, 15-20% activation at concentration below 0.3 mM, maximal activation at 1.25 mM, the activation by SDS and acidic pH results in a localized conformational change that is anchored around the catalytic site of PPO that alters the microenvironment of an essential glutamic residue | Lablab purpureus |  |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide | irreversible inactivation, second-order rate constants | Lablab purpureus | |
| glycine methyl ester hydrochloride | irreversible inactivation, second-order rate constants | Lablab purpureus | |
| tropolone | pseudo first-order rate constants for inactivation | Lablab purpureus | |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| additional information | - |
additional information | the enhancement of kcat upon activation is accompanied by a marked shift in the pH optimum for the oxidation of t-butyl catechol from 4.5 to 6.0, an increased sensitivity to tropolone, altered susceptibility to proteolytic degradation and decreased thermostability | Lablab purpureus |
Molecular Weight [Da]
| Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
|---|---|---|---|
| 12000 | - |
gel filtration | Lablab purpureus |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| additional information | Lablab purpureus | the enzyme is considered as defence oxidative enzyme, is vital the physiological defence strategy adapted by plants to insect herbivory and pathogen attack | ? | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Lablab purpureus | - |
field bean | - |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| native enzyme from seeds | Lablab purpureus |
Reaction
| Reaction | Comment | Organism | Reaction ID |
|---|---|---|---|
| 2 catechol + O2 = 2 1,2-benzoquinone + 2 H2O | the enzymes possesses a core carboxylate essential to activity, this enhanced catalytic efficiency of PPO | Lablab purpureus |
Source Tissue
| Source Tissue | Comment | Organism | Textmining |
|---|---|---|---|
| seed | - |
Lablab purpureus | - |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| 1-butylcatechol + O2 | - |
Lablab purpureus | ? | - |
? | |
| additional information | the enzyme is considered as defence oxidative enzyme, is vital the physiological defence strategy adapted by plants to insect herbivory and pathogen attack | Lablab purpureus | ? | - |
? | |
| additional information | the enzyme shows catecholase and cresolase activities, a type III copper protein that catalyses the O-hydroxylation of monophenols and oxidation of O-diphenols using molecular oxygen | Lablab purpureus | ? | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| More | the Stokes radius of the native enzyme is found to increase from 49.1 to 75.9 A upon activation of the enzyme, neither SDS nor acid-pH activation brought about any change in the quaternary structure | Lablab purpureus |
| tetramer | - |
Lablab purpureus |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| catecholase | - |
Lablab purpureus |
| cresolase | - |
Lablab purpureus |
| polyphenol oxidase | - |
Lablab purpureus |
| PPO | - |
Lablab purpureus |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 25 | - |
assay at | Lablab purpureus |
Temperature Stability [°C]
| Temperature Stability Minimum [°C] | Temperature Stability Maximum [°C] | Comment | Organism |
|---|---|---|---|
| additional information | - |
the activated enzyme is less thermostable than the native enzyme, overview | Lablab purpureus |
| 40 | - |
above, loss in activity | Lablab purpureus |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| additional information | - |
the enhancement of kcat upon activation is accompanied by a marked shift in the pH optimum from pH 4.5 to pH 6.0 for the oxidation of t-butyl catechol from 4.5 to 6.0, an increased sensitivity to tropolone, altered susceptibility to proteolytic degradation and decreased thermostability, overview | Lablab purpureus |
| 4.5 | - |
native enzyme | Lablab purpureus |
| 6 | - |
activated enzyme | Lablab purpureus |
pH Range
| pH Minimum | pH Maximum | Comment | Organism |
|---|---|---|---|
| 3 | 7 | - |
Lablab purpureus |
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