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Literature summary extracted from

  • Gawlik-Dziki, U.; Zlotek, U.; Swieca, M.
    Characterization of polyphenol oxidase from butter lettuce (Lactuca sativa var. capitata L.) (2007), Food Chem., 107, 129-135.
No PubMed abstract available

Inhibitors

EC Number Inhibitors Comment Organism Structure
1.14.18.1 ascorbic acid in descending order of inhibition potency: p-hydroxybenzoic acid > glutathione = ascorbic acid > L-cysteine > EDTA > citric acid Lactuca sativa
1.14.18.1 Citric acid in descending order of inhibition potency: p-hydroxybenzoic acid > glutathione = ascorbic acid > L-cysteine > EDTA > citric acid Lactuca sativa
1.14.18.1 EDTA in descending order of inhibition potency: p-hydroxybenzoic acid > glutathione = ascorbic acid > L-cysteine > EDTA > citric acid Lactuca sativa
1.14.18.1 glutathione in descending order of inhibition potency: p-hydroxybenzoic acid > glutathione = ascorbic acid > L-cysteine > EDTA > citric acid Lactuca sativa
1.14.18.1 L-cysteine in descending order of inhibition potency: p-hydroxybenzoic acid > glutathione = ascorbic acid > L-cysteine > EDTA > citric acid Lactuca sativa
1.14.18.1 p-hydroxybenzoic acid in descending order of inhibition potency: p-hydroxybenzoic acid > glutathione = ascorbic acid > L-cysteine > EDTA > citric acid Lactuca sativa

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
1.14.18.1 1
-
 4-methylcatechol
-
 Lactuca sativa
1.14.18.1 3.2
-
 catechol
-
 Lactuca sativa

Molecular Weight [Da]

EC Number Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
1.14.18.1 60000
-
 SDS-PAGE Lactuca sativa

Organism

EC Number Organism UniProt Comment Textmining
1.14.18.1 Lactuca sativa
-
 var. capitata L.
-

Purification (Commentary)

EC Number Purification (Comment) Organism
1.14.18.1 partial purification Lactuca sativa

Specific Activity [micromol/min/mg]

EC Number Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
1.14.18.1 additional information
-
 26285 U/mg. An increase in absorbance of 0.001 min-1 is taken as one Unit of enzyme activity. G-100, purification step Lactuca sativa

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
1.14.18.1 4-methylcatechol + 1/2 O2 PPO from butter lettuce shows a higher affinity to 4-methylcatechol than to catechol Lactuca sativa 4-methyl-1,2-benzoquinone + H2O
-
 ?
1.14.18.1 caffeic acid + 1/2 O2
-
 Lactuca sativa caffeoyl quinone + H2O
-
 ?
1.14.18.1 catechol + 1/2 O2 PPO from butter lettuce shows a higher affinity to 4-methylcatechol than to catechol Lactuca sativa o-benzoquinone + H2O
-
 ?
1.14.18.1 chlorogenic acid + 1/2 O2
-
 Lactuca sativa chlorogenoquinone + H2O
-
 ?
1.14.18.1 ferulic acid + O2 + AH2
-
 Lactuca sativa (2E)-3-(3,4-dihydroxy-5-methoxyphenyl)prop-2-enoic acid + H2O + A
-
 ?
1.14.18.1 additional information no activity with vanillin and tyrosine as a substrate Lactuca sativa ?
-
 ?

Synonyms

EC Number Synonyms Comment Organism
1.14.18.1 polyphenol oxidase
-
 Lactuca sativa
1.14.18.1 PPO enzyme catalyses two distinct reactions: the o-hydroxylation of monophenols to o-diphenols (acts like cresolase) (E.C. 1.14.18.1) and the oxidation of o-diphenols to o-quinones (acts like catecholase) (E.C. 1.10.3.2) Lactuca sativa

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
1.14.18.1 35
-
-
 Lactuca sativa

Temperature Stability [°C]

EC Number Temperature Stability Minimum [°C] Temperature Stability Maximum [°C] Comment Organism
1.14.18.1 30 40 enzyme is relatively stable at 30°C and 40°C. Thermal stability of partially purified PPO is investigated at pH 6.8 at various constant of temperatures from 25°C to 70°C using incubation time from 10 to 60 min. Residual PPO activity is then measured using 10 mM catechol substrate Lactuca sativa

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
1.14.18.1 5.5
-
 catechol as a substrate Lactuca sativa
1.14.18.1 6.8
-
 4-methylcatechol as a substrate Lactuca sativa

pH Stability

EC Number pH Stability pH Stability Maximum Comment Organism
1.14.18.1 additional information
-
 PPO activity, as a function of pH, is determined under standard conditions using various buffers in the pH buffering range 2.0-12.0 Lactuca sativa

IC50 Value

EC Number IC50 Value IC50 Value Maximum Comment Organism Inhibitor Structure
1.14.18.1 4.54
-
-
 Lactuca sativa p-hydroxybenzoic acid
1.14.18.1 4.61
-
-
 Lactuca sativa ascorbic acid
1.14.18.1 4.7
-
-
 Lactuca sativa glutathione
1.14.18.1 10.39
-
-
 Lactuca sativa L-cysteine
1.14.18.1 26.4
-
-
 Lactuca sativa EDTA
1.14.18.1 62.91
-
-
 Lactuca sativa Citric acid