冻存茶鲜叶多酚氧化酶动力学特性研究

Study on Reaction Kinetics Characteristics of Polyphenol Oxidase of Cryopreservation Fresh Tea Leaves

采用分光光度法对冻存处理的茶树鲜叶的多酚氧化酶（PPO）进行了活性测定,研究了底物浓度、pH值及温度对冻存茶鲜叶PPO活性的影响,建立了茶树鲜叶冻存-萎凋过程的反应动力学方程。结果表明,冻存茶鲜叶PPO酶活的最适条件为：pH值介于4.6~5.0之间,温度35~60℃。由Michaelis-Menten方程1/v=1.168 8/[S]＋3.083 3,得到的动力学参数为：Km=0.378 mol/L,vmax=0.324 U/min。

The polyphenol oxidase activity of cryopreservation fresh tea leaves was determined by spectrophotometric method.The influence of main factors,such as substrate concentration,system pH and temperature on catalytic activities of PPO were investigated.The results showed that,the optimum pH and temperature for the enzymatic reaction was 4.6~5.0 and 35~60 ℃,respectively.The Michaelis-Menten equation of PPO from cryopreservation fresh tea leaves was established,accordingly1/v=1.168 8/[S]＋3.083 3,by which the kinetic parameters obtained were as follow： Km=0.378 mol/L,vmax=0.324 U /min.