【摘要】 在库蚊Culexpipiens品系中 ,非专一性酯酶活性的升高是对有机磷杀虫剂产生抗性的重要机理之一。应用SDS/PAGE ,比较淡色库蚊Culexpipienspallens抗敌百虫品系 (RD)、敏感型品系 (S)和抗苄呋菊酯品系 (PY)中可溶性总蛋白质带型 ,显示RD中含有一条特异蛋白带 ,其它两个品系中未检出。在RD成虫匀浆液总蛋白中含量高达 2 1%。分子量测定为 66kD。应用柱层析法分离得到了较纯的纯品。以α NA为底物测得Km =64 1mmol/L ,Vmax=2 4 9 8mmol/(L·mg·min)。与羧酸酯酶相比较 :其Km 值小于已报道的抗性品系及非抗性品系A 酯酶和B 酯酶。Vmax值比已报道抗性品系A 酯酶低 ,比B 酯酶高。较高浓度的敌百虫并不能抑制其酶活 ,属于A 酯酶。在昆虫体内可能主要通过结合隔离作用 (sequestration)提高昆虫对有机磷的耐受性 ,对有机磷杀虫剂水解作用的可能性也不能排除更多还原

【Abstract】 In Culex pipiens, resistance to organophosphate insecticides was recognized to be correlated with the increased non specific esterase activity. From a dipterex resistant mosquito strain (RD) of Culex pipiens pallens a special protein band was confirmed on SDS/PAGE spectrum. The identified band was not detectable in the susceptible strain(S) or the resmethrin resistant strain (PY).This band represented a protein of MW 66 kD with pI value 4 6 ,which displayed carboxyesterase activity and accounted for 2 1% of the total extractable proteins. The purification of this protein was performed in turn by phenyl sepharose (CL 4B), DEAE cellulose (DE 5L) and FPLC column chromatographic procedures. Enzymological kinetics demonstrated a K m value of 64 1 mmol/L and a V max value of 249 8 mmol/(L·mg·min) with α naphthol acetate as substrate. Dipterex could not inhibit its esterase activity, suggesting the 66 kD protein to be an A esterase. Comparing with other esterase, it had lower K m value and V max value (except higher V max value than B esterase). Further study exhibited that the 66 kD protein might play a role in insect resistance to organophosphate insecticide, mainly through sequestration effect. Nevertheless, the role of hydrolyzing activity at a minor extent could not be excluded.更多还原