›› 2007, Vol. 50 ›› Issue (10): 981-988.

• 研究论文 • 上一篇    下一篇

粘虫中肠α-淀粉酶活性测定方法的参数优化

孔玉萍,黄青春,刘曼慧,丰俊,刘扬   

  • 出版日期:2007-10-20 发布日期:2007-11-23
  • 通讯作者: 黄青春

Parametric optimization on the sensitive determination of midgut α-amylase in larvae of Mythimna separata Walker

  • Online:2007-10-20 Published:2007-11-23

摘要: 针对粘虫Mythimna separata中肠α-淀粉酶筛选了11种不同参数组合的3,5-二硝基水杨酸活性测定方法,并对其中最适组合的各个参数进行了优化。结果表明:在离体测定条件下,粘虫中肠α-淀粉酶活性的最优化测定参数为0.03 mol/L 磷酸盐缓冲液(pH 8.0,含有55 mmol/L NaCl)、温度45℃、吸收波长480 nm。Ca2+对α-淀粉酶活性具有抑制作用。该优化法能够显著降低粘虫、德国小蠊Blattella germanica、黄粉虫Tenebrio molitor、淡色库蚊Culex pipiens pallens和家蝇Musca domestica等昆虫α-淀粉酶的米氏常数Km值,且粘虫和德国小蠊α-淀粉酶的Vmax值增大,但黄粉虫、淡色库蚊和家蝇α-淀粉酶的Vmax值均明显减小。结果说明,在该优化体系下,粘虫α-淀粉酶与底物的亲和力增强,最大反应速度增大,测定酶活性的准确性和灵敏度显著提高;同时该优化体系也可作为测定德国小蠊α-淀粉酶活性的优化方法,但不适合作为黄粉虫、淡色库蚊和家蝇α-淀粉酶的最优化测定方法。

关键词: 粘虫, α-淀粉酶, 参数优化, 动力学常数

Abstract: Parametric optimization on the activity determination of midgut α-amylase in larvae of Mythimna separate Walker was investigated by screening the 3,5 dinitrosalicylic acid methods with eleven combinations of parameters. The results showed that the in vitro determined optimal parameters were 0.03 mol/L phosphate buffer (pH 8.0) containing 55 mmol/L NaCl, reaction temperature 45℃ and absorbance wavelength 480 nm. Ca2+ inhibited the activity of α-amylase. Moreover,  the optimal method significantly decreased Km value of α-amylase from M. separate, Blattella germanica,  Tenebrio molitor,  Culex pipiens pallens and Musca domestica larvae,  and increased Vmax  value of α-amylase from M. separate and B. germanica, but strongly decreased Vmax values of α-amylase from T. molitor,  C. pipiens pallens and M. domestica larvae. The study suggested that the optimal method not only enhanced the affinity and the maximum reaction velocity of α-amylase with its substrate, but also improved the accuracy and the sensitivity on the activity of α-amylase from M. separate larvae in assays, whereas it was not the optimal method for determining the activity of α-amylase from T. molitor,  C. pipiens pallens  and M. domestica larvae.

Key words: Mythimna separata, α-amylase, parametric optimization, kinetic constant