摘要
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 equation was also established. The results showed that the optimum temperature and pH are 60℃ and pH6.0, respectively. The reaction kinetics of enzymatic browning accords with Michaelis Equation model. The Km, Vmax and kinetics equation are 0. 003 2 mol/L, 428. 786 U/min · g and V =428. 786[ S]/（0. 003 2 ＋ [ S] ） using guaiacolas as substrate, respectively. Five different inhibitors demonstrate different effects on enzymatic browning of POD, and the inhibiting 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.
出处
《食品与发酵工业》
CAS
CSCD
北大核心
2010年第8期55-58,63,共5页
Food and Fermentation Industries
