Characterization of polyphenol oxidase from Napoleon grape

Purification and characterisation of polyphenol oxidase from leaves of Cleome gynandra L.

“…L-Cysteine was proposed to react with the copper of PPO to form stable complexes and thus directly inhibit the enzyme activity (Nicholas, Richard-Forget, Goupy, Amiot, & Aubert, 1994). The Cu 2+ chelator SDDC was also thought to act by complexing the copper prosthetic group of the PPO and thus leading to entire loss of catalytic activity of the emzyme (Núñez-Delicado, Serrano-Megías, Pérez-López, & López-Nicolás, 2007). Ascorbic acid might reduce the initial quinone formed by PPO catalysis back to diphenol before it undergoes a secondary reaction that leads to browning, and therefore, it acted as an antioxidant rather than as an enzyme inhibitor, although it may cause irreversible inhibition (Golan-Goldhirsh & Whitaker, 1984).…”

Assessment of oxidation of leaves of Ilex paraguariensis (St. Hil)

“…pH is an important factor influencing enzyme activity (Lehninger, 2006) and can affect the oxidative enzymes in vegetables (peroxidases and polyphenoloxidases). Studies with brussels sprouts found as pH 9 the optimal for the activity and stability of polyphenoloxidases (Nagai and Suzuki, 2003).The effect of pH on the activity of polyphenoloxidases has been extensively studied for fruits, juice and vegetables with preservative agent inhibiting the oxidation of color modifications and browning of explants in tissue culture (Niu et al, 2010;Lin et al, 2010;Wu et al, 2010;Dziki et aL., 2008;Dziki et al,2007;Delicado et al, 2007;Mayer et al, 2006). However, the relationship between the pH and polyphenol oxidase activity in the oxidation process the leaves of yerba mate to be utilized in the form of tea is still a recent study.…”

Deriphat 2‐DE to visualize polyphenol oxidase in Moscato and Prosecco grapes

“…1b), a range which may be considered in optimizing zymogram assays. Taking into account previous results of PPO grape activity monitored in SDS-PAGE [2,6], we carried out trials in SDS-PAGE, considered to have a denaturing effect by Mayer and Harel [18]. The PPO of both varieties was detected by SDS-PAGE (Fig.…”

“…It has also been noted that heat inactivation of PPO is unsuitable for anthocyanin-containing juice products, since the temperatures required for PPO inactivation impair anthocyanin. Therefore, to develop more effective methods, i.e., specific enzyme inhibitors for controlling browning, it is necessary to use other approaches in PPO characterization, as reported by Núñez-Delicado et al [6]. In this respect, the proteomic approach can identify these enzymes, facilitating their biochemical characterization.…”