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用苏云金杆菌(Bt)预处理24h后,棉铃虫幼虫体内乙酰胆碱酯酶对特异性酶抑制剂的亲和力发生了变化。在抗性品系中,幼虫的乙酰胆碱酯酶的酶动力学值和抑制中浓度均低于未处理对照幼虫,双分子速率常数则高于未处理对照幼虫,单位时间内抑制作用加快,差异显著,说明Bt预处理可能改变或激活了抗性幼虫乙酰胆碱酯酶的活化中心,因而增加了其幼虫乙酰胆碱酯酶与抑制剂的亲和力。由此推论,乙酰胆碱酯酶的改变是Bt预处理棉铃虫幼虫对杀虫剂敏感性提高的重要原因之一。Bt预处理和未处理敏感幼虫的双分子速率常数没有变化,但酶最大反应速度及抑制中浓度值升高,表明Bt预处理降低了敏感幼虫乙酰胆碱酯酶单位时间内的抑制作用,导致酶促反应速度加快,同时增加了对乙酰胆碱酯酶的半抑制剂量。
After 24h pretreatment with Bacillus thuringiensis (Bt), the affinity of acetylcholinesterase to specific enzyme inhibitors in cotton bollworm larvae changed. In the resistant strains, laccase acetylcholinesterase enzyme activity and inhibitory concentrations were lower than the untreated control larvae, bimolecular rate constant was higher than the untreated control larvae, the unit of time to inhibit the role of accelerated, the difference was significant, This indicated that pretreatment of Bt might change or activate the activation center of the resistant larvae of AChE, thus increasing the affinity of its larval AChE to the inhibitor. Therefore, it is concluded that the change of acetylcholinesterase is one of the important reasons for the insecticide sensitivity of Bt pretreated cotton bollworm larvae. The bimolecular rate constants of Bt pretreated and untreated sensitive larvae did not change, but the maximal enzyme reaction rate and the medium inhibitory concentration increased, indicating that Bt pretreatment reduced the inhibition of acetylcholinesterase per unit time in sensitive larvae, The reaction speed increases, while increasing the half-inhibitory dose of acetylcholinesterase.