菜青虫不同虫态及虫龄的多酚氧化酶性质比较  

Comparison on properties of polyphenoloxidase from Pieris rapae(L.) in different stages and instars

作　　者：薛超彬[1] 陈清西[2] 王勤[2] 柯莉娜[2] 罗万春[1] 

机构地区：[1]山东农业大学植物保护学院,农药毒理与应用技术省级重点实验室,山东泰安271018 [2]厦门大学生命科学学院教育部细胞生物学与肿瘤细胞工程重点实验室,福建厦门361005

出　　处：《昆虫学报》2004年第3期305-309,共5页Acta Entomologica Sinica

基　　金：国家自然科学基金项目 (3 0 2 70 887) ;博士后科学基金项目

摘　　要：初步比较了菜青虫Pierisrapae (L .)不同虫态及虫龄的多酚氧化酶 (polyphenoloxidase)的性质。结果表明 ,不同虫态及虫龄的多酚氧化酶活力有很大的不同 ,其中以 5龄幼虫酶活力最高 ,蛹酶活力最低。酶活力大小依次为 :5龄幼虫 >预蛹 >4龄幼虫 >3龄幼虫 >蛹。以邻苯二酚为底物 ,研究了pH对多酚氧化酶活力的影响 ,结果表明酶催化底物氧化均有一个最适pH区域 ,不同虫态及虫龄的多酚氧化酶最适pH基本相同 ,其值为 7 0± 0 2。不同虫态及虫龄的多酚氧化酶催化底物氧化的最适温度有很大的差异。 3龄、4龄、5龄幼虫、预蛹和蛹的多酚氧化酶活力的最适温度分别为 36 0± 0 5℃、38 5± 1 0℃、4 3 0± 1 0℃、4 5 5± 1 0℃和 5 0 0± 1 5℃ ,说明蛹期的多酚氧化酶活力的最适温度较高。进一步比较催化底物氧化反应的活化能 ,测得 3龄、4龄、5龄幼虫、预蛹和蛹的多酚氧化酶活化能分别为 :4 3 10± 0 2 8、36 5 0± 0 2 7、2 5 79± 0 32、30 10± 0 2 1和 5 8 88± 0 39kJ mol。通过测定不同虫态及虫龄的多酚氧化酶催化邻苯二酚和L_多巴氧化反应的动力学特征参数 ,比较了不同虫期的酶对底物的亲和力。The kinetic properties of polyphenoloxidase (PPO) from Pieris rapae (L.)in different stages and instars were studied and compared. The results showed that the polyphenoloxidase activity was different at different stages and instars in this insect. The enzyme activity of the 5th instar was the highest and that of the pupa was the lowest. The order of the enzyme activity was the 5th instar > prepupa > the 4th instar > the 3rd^( )instar > pupa. The effect of pH on the activity of polyphenoloxidase was studied, and the results showed that the optimum pH was the same value in all of the stages and instars and the best pH value for the oxidation of catechol was 7.0±0.2. The optimum temperature of the polyphenoloxidase activity was very variable in the tested stages and instars of the insect. The optimum temperature for the 3rd instar, 4th instar, 5th instar, prepupa and pupa was 36.0±0.5℃, 38.5±1.0℃, 43.0±1.0℃, 45.5±1.0℃ and 50.0±1.5℃, respectively, indicating that the optimum temperature of the pupa was the highest.The activation energy of the enzyme from this insect for the oxidation of catechol was 43.10±0.28, 36.50±0.27, 25.79±0.32, 30.10±0.21 and 58.88±0.39 kJ/mol for the 3rd instar, 4th instar, 5th instar, prepupa and pupa, respectively. The kinetic parameters for the oxidation of catechol and L-DOPA by polyphenoloxidase from the different stages and instars were determined and compared.

关 键 词：菜青虫 多酚氧化酶 酶活力 动力学性质 

分 类 号：Q965.9[生物学—昆虫学]