以愈创木酚为底物,470 nm处测定"黑美人"马铃薯过氧化物酶(POD)的活性,研究了温度、pH、底物浓度对其活性的影响,并建立了酶促褐变反应动力学方程,探讨了L-半胱氨酸、抗坏血酸、柠檬酸、EDTA及亚硫酸氢钠5种抑制剂和CuSO4、FeCl3两种激活剂对酶促褐变的影响。结果表明:"黑美人"马铃薯过氧化物酶最适反应pH为pH6.0,最适反应温度为60℃,酶促褐变反应动力学符合米氏方程描述的单底物酶促反应动力学。以愈创木酚为底物,Km=0.0032 mol/L,Vmax=428.786 U/(min.g),动力学方程为V=428.786[S]/(0.003 2+[S])。5种抑制剂对POD酶促褐变均具有抑制作用,其强弱依次为抗坏血酸>L-半胱氨酸>亚硫酸氢钠>柠檬酸>EDTA;2种激活剂对POD酶促褐变均具有促进作用,其强弱依次为CuSO4>FeCl3。

The activity of Heimeiren potato peroxidase(POD) was measured at 470 nm using guaiacol as sub-strate.The effects of temperature,pH,substrate concentration on POD were studied and the reaction kinetics equa-tion was also established.The results showed that the optimum temperature and pH are 60℃ and pH6.0,respective-ly.The reaction kinetics of enzymatic browning accords with Michaelis Equation model.The Km,Vmax and kinetics e-quation are 0.003 2 mol/L,428.786 U/min.g and V = 428.786[S]/(0.003 2 +[S]) using guaiacolas as sub-strate,respectively.Five different inhibitors demonstrate different effects on enzymatic browning of POD,and the in-hibiting order is as follows: ascorbic acid > L-cysteine > sodium bisulfite > citric acid > EDTA.Two activators also have promotional effect on enzymatic browning,and the promotion order is: copper sulfate > ferric chloride.