磁场和抑制剂对莲藕多酚氧化酶反应动力学的影响

通过添加Vc和外加磁场处理,研究莲藕多酚氧化酶(PPO)反应动力学的变化规律.以邻苯二酚为底物,莲藕PPO褐变反应动力学符合米氏方程所描述的单底物酶促反应动力学,Km为0.775 mol/L,Vmax为11.150 U/min.Vc对PPO有较强的抑制作用,反应动力学参数Km为0.081 mol/L,Vmax为3.243 U/min,呈现反竞争性抑制,表现为褐变出现滞后,随Vc浓度的增大滞后时间逐渐增长,且呈现S型趋势,并建立了相应的反应方程.不同磁场强度下,随着处理时间的变化,PPO活性呈现波动性.3.17 A/m磁场强度下处理4 h的酶液其反应动力学曲线表现为S型,并建立了相应的反应方程.

Effect on Reaction Dynamics of Lotus Root Polyphenol-oxidase by Inhibitors and Magnetic Field

The change law of reaction dynamics was experimental studied through adding Vc to lotus root polyphenol-oxidase and dealing with lotus root polyphenol-oxidase(PPO)by magnetic field.The experimental results indicated that the reaction kinetic of enzymatic browning was accordant with Michaelis equation with catechol substrate,which Km and Vmax were 0.775 mol/L and 11.150 U/min respectively.Vc had an inhibiting effect on lotus root PPO,which Km and Vmax were 0.081 mol/L and 3.243 U/min respectively.The browning was lagged and the lag time increased gradually with the rise in the concentration of the inhibitors,which was an anticompetitive inhibition.The PPO activity expressed a fluctuation at different magnetic field strengths and times.At 3.17 A/m magnetic field strength for 4 hours,the reaction kinetics curve was a wave-type curve.The kinetic equations were established respectively.