Prabhakaran S K, Kamble S T
Department of Entomology, University of Nebraska, Lincoln 68583-0816, USA.
Insect Biochem Mol Biol. 1995 Apr;25(4):519-24. doi: 10.1016/0965-1748(94)00093-e.
The most active forms of esterases (E5, E6 and E7) from the German cockroach, Blattella germanica (L.) were purified from resistant and susceptible strains. About 45-155 fold purification with a 11-16% of total esterase recovery was achieved after different column chromatography and preparative gel electrophoresis. Elution profiles of resistant and susceptible strains were similar, but esterase E6 activity was higher in the resistant strains. Kinetic analyses indicate no differences in Km values between the resistant and susceptible strains. However Vmax was significantly higher in resistant strains. Inhibition of esterase activity by paraoxon, chlorpyrifos and propoxur did not suggest any structural differences in esterase E6 between strains. From these results we suggest that insecticide resistance in German cockroach is due to the increased production of E6 esterase. The role of E6 may be sequestration of toxic molecules rather than hydrolysis.
从德国小蠊（Blattella germanica (L.)）的抗性品系和敏感品系中纯化出了酯酶（E5、E6和E7）的最活跃形式。经过不同的柱色谱和制备性凝胶电泳后，实现了约45 - 155倍的纯化，总酯酶回收率为11 - 16%。抗性品系和敏感品系的洗脱图谱相似，但抗性品系中酯酶E6的活性更高。动力学分析表明，抗性品系和敏感品系之间的Km值没有差异。然而，抗性品系中的Vmax显著更高。对氧磷、毒死蜱和残杀威对酯酶活性的抑制作用并未表明品系间酯酶E6存在任何结构差异。根据这些结果，我们认为德国小蠊对杀虫剂的抗性是由于E6酯酶产量增加所致。E6的作用可能是隔离有毒分子而非水解。
