Muscadine Grape Polyphenoloxidase: Partial Purification by High Pressure Liquid Chromatography and Some Properties

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Abstract
A rapid method of isolating grape polyphenoloxidase (PPO) was developed, using two muscadine cultivars, “Noble” and “Welder”. PPO extracts from acetone powders were partially purified followed by filtration through 0.2μ membrane filter by HPLC. Reactivity of the active fraction per unit protein, increased 10‐fold for Noble and 33‐fold for Welder cultivars over values for the corresponding crude extracts. Electrophoretic analysis and activity stain showed that the enzyme displayed a single band in Welder and two bands for Noble. Optimum pH for PPO activity in Welder was pH 4.5 while that for Noble was pH 4.5–5.5. The enzyme in the Noble cultivar was relatively more active at alkaline pH. Activites of the enzymes were stable at temperatures up to 30°C for both cultivars.