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consequence of oxidative degradation of phenolic compounds by polyphenol oxidase (PPO), which leads to production of quinones that polymerize rapidly to form brown-colored products ( Kader and Chordas, 1984 ). The concentration of phenolic compounds, the
Localization of enzymes in specific plant tissues is crucial to understanding their role in processes such as differentiation and disease resistance. The oxidative enzymes lipoxygenase (LOX; EC 1.13.11.12), peroxidase (PER, EC 1.11.1.7) and polyphenol oxidase (PPO; EC 1.10.3.1) have all been implicated as playing critical roles in plant disease resistance. The histochemical localization of all three enzymes in potato tuber slices was accomplished either directly on the tissue slices (for LOX) or by blotting of the tissue onto nitrocellulose membranes (for PER and PPO). LOX was visualized in specific tissues by the oxidation of KI to I2 via lipid peroxides and the subsequent reaction of I2 and endogenous starch to form a colored, insoluble complex. PER and PPO activities were visualized with 4-methoxy-α-naphthol and 3,4-dihydroxy-phenylalanine, respectively. Fractionation of the slices and determination of enzyme activities in the fractions confirmed the reliability of these techniques.
the enzymatic browning and the polyphenol–polyphenol oxidase complex of apple cultivars Confructa. 21 24 31 Vaughn, K.C. Duke, S.O. 1984 Function of polyphenol oxidase in higher plants Physiol. Plant. 60
character of cider is complex and dependent on concentrations of several classes of compounds, the flavanol class of polyphenols is especially important to cider quality because it imparts bitterness and astringency characteristics provided by traditional
heartwood formation in walnut and cherry Can. J. Bot. 56 626 634 10.1139/b78-070 Piffaut, B. Metche, M. 1991 Properties of peroxidase and polyphenol oxidase in natural complexes from walnuts ( Juglans regia ) and in
Fusarium oxysporum f. sp. lycopersici or F. oxysporum f. sp. melonis Caryologia 42 103 114 Maier, T. Güell, M. Serrano, L. 2009 Correlation of mRNA and protein in complex biological samples FEBS Lett. 583 3966 3973 Mayer, A.M. 2006 Polyphenol oxidases
polyphenol oxidase (PPO) of kiwifruit during 120 d storage at 0 °C. Whole fruits were non-treated (control), dipped in 2% CaCl 2 solution, heat-treated at 47 °C for 5 min (H5), 10 min (H10), 15 min (H15) alone, or in combination with CaCl 2 (2%) solution
damages initiated by ROS, plants have evolved a complex antioxidative system that includes enzymatic antioxidants ( Scandalios, 1993 ). Polyamines, which mainly include spermidine (Spd), spermine (Spm), and Put, are small polycations observed in various
Numerous epidemiological and biomedical studies indicated the consumption of fruits and vegetables rich in polyphenols may help to protect the human body against many chronic diseases such as diabetes, cancer, and cardiovascular ailments
), guaiacol peroxidase (POD) ( C ), lipoxygenase (LOX) ( D ), and polyphenol oxidase (PPO) ( E ) in kiwifruit. The activities were determined daily on Days 0 to 6 in kiwifruit treated with water, ethylene, H 2 S, or in combination at 25 °C. Control: H 2 O; H 2