Polyphenol Oxidase from Allium sp.

Polyphenol oxidase (PPO) was isolated from Allium sp. PPO showed activity to catechol and dl -dopa (K m values were 25 mM for cathecol and 33 mM for dl -dopa; V max values were 666 EU/mL·min for cathecol and 166 EU/mL·min for dl -dopa). Catechol was the most suitable substrate for Allium sp. PPO (lowest K m value). The optimum pH for the PPO was 7.5 on substrates catechol and dl -dopa. Heat inactivation studies showed temperature >40 °C resulted in loss of enzyme activity. Heating for 30 min at 40 °C did not cause a significant loss of enzymatic activity. Allium sp. PPO was significantly inhibited in the presence of ascorbic acid, 2-mercaptoethanol, and sodium metabisulfide. Keywords: Polyphenol oxidase; Allium sp.; inhibitors; herb cheese