Study on Enzymatic Characteristics of Polyphenol Oxidase from Physalis pubescens L.

Abstract:

The enzymatic characteristics of polyphenol oxidase（PPO） from Physalis pubes-cens L. was studied by spectrophotometer at 420 nm. The results showed that the PPO enzyme had the highest activity at pH 7.0 and 35 ℃ and the enzyme activity would been inactivated completely after exposure to 100 ℃ for 2 min. The kinetics of enzyme-catalyzed reaction of PPO was in accord with Michaelis-Menten equation, with Km and Vmax values of 0.025 mol/L and 125 U/min, respectively. In the range designated, it was increasing in inhibitory effects of ascorbic acid, citric acid, NaHSO3, L-Cysteine and EDTA against enzyme activity with the increasing concentration , and the order as follow：ascorbic acid﹥citric acid﹥L-cysteine﹥EDTA﹥NaHSO3.