澳洲青苹多酚氧化酶特性的研究

Characteristics of Polyphenol Oxidase in Granny Smith Apple

以邻苯二酚为底物,对澳洲青苹中的多酚氧化酶进行了探讨。分别研究了pH值、温度、底物浓度及抑制剂等因素对多酚氧化酶活性的影响,结果表明:澳洲青苹多酚氧化酶最适pH值为6.5;最适温度为35℃;90℃处理3min,多酚氧化酶活性基本被抑制;添加浓度为125mg/kg抗坏血酸或者浓度为600mg/kg的柠檬酸或者浓度为50mg/kg的亚硫酸氢钠后,多酚氧化酶活性分别为对照的36%,38%和23%。澳洲青萍多酚氧化酶的米氏方程参数为:Km=0.137mol/L,Vmax=0.460U/min。

The optimum pH, optimum temperature, substrate concentration and the inhibitors of polyphenol oxidase from Granny Smith were analyzed with the catechol substrate. The results showed that the optimal pH and temperature were 6.5 and 35℃, respectively. Once the temperature was over 60℃, PPO became inactive quickly. The PPO was almost inactivated at 90℃ for 3 rain. PPO＇s Mischerlisch Equation parameters Km= 0. 137 mol/L and Vmax = 0. 460 U/rain. Adding 125 mg/kg Vc or 600 mg/kg citric acid or 50 mg/kg NaHSO3 in reaction systems, the activity of PPO decreased to 36%, 38% and 23 %, respectively, compared with the check.