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目的:研究几种抑制剂对水蜜桃多酚氧化酶酶促反应的抑制效应。方法:对水蜜桃多酚氧化酶底物特异性进行分析,在确定最适底物的基础上,采用酶动力学方法研究谷胱甘肽、L-半胱氨酸、氟化钠对水蜜桃多酚氧化酶活性的抑制效应。结果:谷胱甘肽、L-半胱氨酸、氟化钠均能抑制水蜜桃多酚氧化酶活性,3者导致酶活力下降50%的浓度(IC50)分别为0.22,0.06,4.57 mmol/L,其中前两者表现为竞争性抑制,后者为非竞争性抑制;3者对水蜜桃多酚氧化酶的抑制常数分别为0.2435,0.4974,0.43 mmol/L。在降低水蜜桃多酚氧化酶酶活的同时,谷胱甘肽和L-半胱氨酸对酶促反应有延滞作用。结论:谷胱甘肽、L-半胱氨酸、氟化钠均可有效抑制水蜜桃多酚氧化酶酶促反应速率,L-半胱氨酸的抑制效果最强,氟化钠抑制效果最差。本试验可为水蜜桃等果蔬深加工过程中抑制剂的应用提供一定参考。
Objective: To study the inhibitory effect of several inhibitors on the enzymatic reaction of peach polyphenol oxidase. Methods: The substrate specificity of peach polyphenol oxidase was analyzed. Based on the determination of optimum substrates, enzyme kinetic methods were used to study the effects of glutathione, L-cysteine and sodium fluoride on peach Inhibitory effect of polyphenol oxidase activity. Results: Glutathione, L-cysteine and sodium fluoride all inhibited the activity of polyphenol oxidase of peach. The concentrations of IC50 of the three enzymes that caused 50% decrease of enzyme activity were 0.22,0.06,4.57 mmol / L, of which the first two showed competitive inhibition and the latter non-competitive inhibition. The inhibition constants of peach polyphenol oxidase were 0.2435, 0.4974 and 0.43 mmol / L, respectively. While reducing peanut polyphenol oxidase activity, glutathione and L-cysteine have a retardation effect on the enzymatic reaction. CONCLUSION: Glutathione, L-cysteine and sodium fluoride can effectively inhibit the enzymatic reaction rate of polyphenol oxidase of peach, the inhibitory effect of L-cysteine is the strongest, and the inhibitory effect of sodium fluoride is the most difference. This experiment can provide some reference for the application of inhibitors in deep processing of fruits and vegetables such as peach.