Recombinant expression, purification, and characterization of polyphenol oxidase 2 (<i>Vv</i>PPO2) from “Shine Muscat” (<i>Vitis labruscana</i> Bailey × <i>Vitis vinifera</i> L.)

<p>Polyphenol oxidases (PPOs) catalyze browning reactions in various plant organs, therefore controlling the reactions is important for the food industry. PPOs have been assumed to be involved in skin browning of white grape cultivars; however, the molecular mechanism underlying PPO-mediated browning process remains elusive. We have recently identified a new <i>PPO</i> gene named <i>VvPPO2</i> from “Shine Muscat” (<i>Vitis labruscana</i> Bailey × <i>V. vinifera</i> L.), and have shown that the gene is transcribed at a higher level than the previously identified <i>VvPPO1</i> in browning, physiologically disordered berry skins at the maturation stage. In this study, we expressed <i>Vv</i>PPO2 in <i>Escherichia coli</i> and, using the purified preparation, revealed unique physicochemical characteristics of the enzyme. Our study opens up a way to not only understand the berry skin browning process but also to elucidate the enzymatic maturation process of grape PPOs.</p> <p>Characterization of Polyphenol Oxidase 2 (<i>Vv</i>PPO2) from ‘Shine Muscat’ (<i>Vitis labruscana</i> Bailey × <i>Vitis vinifera</i> L.)</p>