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Updated: Aug 25, 2026

Elucidating β-1,3-Glucanase and Peroxidase Physicochemical Properties of Wheat Cell Wall Defense Mechanism Against Diuraphis noxia Infestation
Published on: July 26, 2024
Properties of wheat bran polyphenol oxidase
Ciğdem Soysal1, Zerrin Söylemez
1University of Gaziantep, Faculty of Engineering, Department of Food Engineering, 27310 Gaziantep, Turkey.
Abstract:
Polyphenol oxidase (PPO) obtained from wheat bran catalyzed the oxidation of 4-methyl catechol. Phenolic compounds found naturally in crude extract played role as an endogeneous substrate and activity of crude extract needed correction. Activity versus enzyme concentration gave a linear plot at high substrate concentration whereas a nonlinear plot was obtained at low substrate concentration which proved the presence of endogeneous substrate. Adsorption on celite and extraction with polyvinylpyrrolidone (PVPP) caused the removal of phenols. Adsorption of PPO on celite yielded a 4-fold increase in specific activity whereas extraction with PVPP yielded a 2.5-fold increase in specific activity compared to the crude extract. The kinetics of PPO catalyzed oxidation obeyed Michaelis-Menten model; Km and Vmax values were found as 218 mM and 99 microM/min, respectively. The enzyme was inhibited by ethyl alcohol, dithiothreitol (DTT) and isoproterenol and exhibited heat stability up to a temperature of 90 degrees C. The optimum pH of the enzyme was found to be 5.0.
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