曹州木瓜多酚氧化酶的酶学特性  

Enzymatic characterization of polyphenol oxidase from Caozhou Chaenomeles fruits

作　　者：隋园园[1] 王兆升[1] 李钟涛[2] 王晓丽[1] 程春牛 

机构地区：[1]山东农业大学食品科学与工程学院,山东泰安271018 [2]安丘市农业局,山东安丘262100 [3]菏泽市木瓜研究所,山东菏泽274000

出　　处：《食品与发酵工业》2013年第8期42-46,共5页Food and Fermentation Industries

基　　金：菏泽市科学技术计划项目(111D656098)

摘　　要：摘要以邻苯二酚为底物，采用分光光度法对曹州木瓜多酚氧化酶（PPO）的酶学特性进行了研究。结果表明：曹州木瓜PPO的最适pH为5．0，最适温度为300C；PPO在60—90℃内的热失活曲线具有双相特征，活化能Ea=112．95kJ／mol；PPO催化的酶促褐变反应动力学符合米氏方程，且相应动力学参数为Km=6．92mmol／L，Vmax=769．23U；5种抑制剂对PPO的抑制效果从大到小依次为：亚硫酸氢钠〉抗坏血酸（Vc）〉L一半胱氨酸（L-cys）〉柠檬酸〉EDTA．2Na；Na＋和K＋对PPO活性的影响不明显，Al3＋、Ba2＋、Cu2＋对PPO具有抑制作用，Mg2＋、Mn2＋、Ca2＋在低浓度（1mmol／L）时对PPO具有激活作用，高浓度（10mmol／L）时具有抑制作用。Enzymatic characterization of polyphenol oxidase （PPO） from Caozhou Chaenomeles sinensis was de- termined spectrophometrically using catechol as substrate. The results showed that the optimum pH and temperature for the enzymatic oxidation were 5.0 and 30℃ , respectively. Thermal inactivation between 60 and 90℃ was observed to be biphasic with activation energy of 112.95 kJ/mol. The reaction kinetic for PPO-catalyzed browning was in ac- cord with Michaelis-Menten equation, where the Michaelis constant Km and the maximum velocity value Vmax were 6.92 mmol/L and 769.23 U, respectively. NaHSO3 , ascorbic acid, L-cys, citric acid and EDTA-2Na significantly inhibited the PPO activity in the order of NaHSO3 〉 ascorbic acid 〉 L-cys 〉 citric acid 〉 EDTA-2Na. Na ~ and K ~ had no effect on PPO activity. The decreased PPO activity was observed in presence of A13 ＋ , Ba2 ＋ and Cu2 ＋. Mg2＋ , Mn2＋ and Ca2＋ activated PPO at lower concentration （1 mmol/L） while inhibited at higher concentration （10 mmol/L）.

关 键 词：曹州木瓜 多酚氧化酶 酶学特性 抑制剂 金属离子 

分 类 号：TQ925[轻工技术与工程—发酵工程]