砀山酥梨多酚氧化酶酶学特性及抑制效应的研究  

Study on Polyphenol Oxidase (PPO) Character and Inhibiting Effects of Dangshan Pear

作　　者：徐芹[1] 乔勇进[1] 方强[2] 张绍铃[1] 王海宏[1] 

机构地区：[1]南京农业大学园艺学院,江苏南京210095 [2]上海市农业科学院农产品保鲜加工研究中心,上海201106

出　　处：《食品科学》2008年第4期74-77,共4页Food Science

基　　金：农业部“948”梨项目(2001-102-06)

摘　　要：多酚氧化酶是酶促褐变的关键酶,其特性与对其抑制效应研究一直是果蔬酶促褐变生理生化研究的重要内容,本试验以邻苯二酚为底物,采用分光光度法对砀山梨多酚氧化酶的酶学特性及不同抑制剂对多酚氧化酶活性的影响进行了研究。结果表明:砀山梨PPO的最适pH为4.5,最适温度为34℃;短时间高温能显著抑制PPO活性;PPO催化的酶促褐变反应动力学符合米氏方程,该酶促反应的最大速率为178.57U/min,酶反应速度为最大反应速度1/2时的底物浓度为0.125mol/L;柠檬酸、L-半胱氨酸、抗坏血酸,亚硫酸氢钠较柠檬酸能较好地抑制PPO活性,随着浓度的升高,抑制效应逐渐增强,但综合研究表明L-半胱氨酸抑制效应较好。Polyphenol oxidase （PPO） is the key enzyme of enzymatic browning, and its characteristics and inhibiting effects are the important involvements of studying enzymatic browning of fruit and vegetable. With spectrophotometry method and based on substrate of catechol, the characteristics of PPO and the effects of various inhibitors on PPO activity were investigated. The results showed that the optimum pH-activity is 4.5, and the optimum temperature for pear PPO activity is 34 ℃, so the high temperature short time treatment can inhibit PPO activity evidently. The kinetics of the enzyme-catalyzed reaction of PPO is in accord with Michaclis-Menten equation, whereas Km and Vmax values are respectively 0.125 mol/L and 178.57 U/rain. Of the inhibitors tested, L-cysteine, sodium bisulphite or ascorbic acid is more effective than citric acid, and the most effective inhibitor is L-cysteine.

关 键 词：砀山酥梨 多酚氧化酶 酶学特性 抑制效应 

分 类 号：Q554.1[生物学—生物化学]