›› 2004, Vol. 47 ›› Issue (3): 305-309.doi:

• 研究论文 • 上一篇    下一篇

菜青虫不同虫态及虫龄的多酚氧化酶性质比较

薛超彬1, 陈清西2, 王勤2, 柯莉娜2, 罗万春1*   

  • 出版日期:2004-06-20 发布日期:2004-06-20

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

XUE Chao-Bin1, CHEN Qing-Xi2, WANG Qin2, KE Li-Na2, LUO Wan-Chun1*   

  • Online:2004-06-20 Published:2004-06-20
  • Contact: LUO Wan-Chun

摘要: 初步比较了菜青虫Pieris rapae (L.)不同虫态及虫龄的多酚氧化酶(polyphenol oxidase)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℃、43.0±1.0℃、45.5±1.0℃和50.0±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±0.28、36.50±0.27、25.79±0.32、30.10±0.21和58.88±0.39 kJ/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。

关键词: 菜青虫, 多酚氧化酶, 酶活力, 动力学性质

Abstract: 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.±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, 5.79±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.

Key words: Pieris rapae; polyphenoloxidase, enzyme activity, kinetic properties