Identification of polyphenol oxidases in potato tuber (Solanum tuberosum) and purification and characterization of the major polyphenol oxidases

Potato is widely consumed across the globe. Understanding and inhibiting the oxidation caused by polyphenol oxidase (PPO) could improve shelf life and increase the nutritional and economic value of potato proteins. This study aimed to identify and quantify all expressed PPOs in potato tuber (Solanum tuberosum) and to purify and characterize the major PPOs responsible for oxidase activity. Four different PPOs were expressed in potato tuber, with 2 PPOs constituting the majority. These 2 PPOs were copurified and characterized. Both potato juice and the purified PPOs had an optimum pH of 5 and were stable over a broad pH range (6-11). The optimum temperature and stability varied, with potato juice having an optimum at 30 degrees C and showing a gradual decline in oxidase activity with increasing incubation temperature, while the purified PPOs had an optimum temperature and were stable up to 40 degrees C. Reducing agents effectively inhibited oxidase activity, while chelators did not.

Automated summary

This study identified multiple PPOs in potatoes, with two major ones showing stability at pH 5 and different optimal temperatures. It was found that reducing agents effectively inhibited oxidase activity, while chelators did not have the same effect.