花翅摇蚊乙酰胆碱酯酶的底物专一性及对胆碱酯酶抑制剂敏感度的比较

Substrate Specificity of Acetylcholinesterase and Its Sensitivity to Cholinesterase Inhibitor in Chironomus kiinensis

摇蚊是重要的水生昆虫,可用于水环境质量的生物学评价.本研究以花翅摇蚊(Chironomus kiinensis)为材料,研究了花翅摇蚊乙酰胆碱酯酶(Acetylcholinesterase,AChE)的底物专一性及其对胆碱酯酶抑制剂的敏感度.结果表明,花翅摇蚊AChE对乙酰硫代胆碱(ATCh)的水解活性最高,其次是β-甲基硫代乙酰胆碱(β-MTCh)、丙酰硫代胆碱(PrTCh)和丁酰硫代胆碱(BuTCh);氨基甲酸酯药剂对花翅摇蚊AChE的抑制能力高于有机磷类,其中克百威对摇蚊AChE的抑制能力最强,I50值为1×10-8molL-1.有机磷和氨基甲酸酯类抑制剂对摇蚊AChE的抑制趋势基本一致,均随着抑制时间延长,抑制率不断增加.由此可得出,花翅摇蚊AChE的最适底物是ATCh;离体条件下,摇蚊AChE对低浓度的有机磷和氨基甲酸酯药剂比较敏感.

As an important aquatic insect, chironomid was often used to assess the quality of water. A comparative study on substrate specificity of acetylcholinesterase （ AChE ） from Chironomus kiinensis and its sensitivity to cholinesterase inhibitors was investigated in vitro. The results showed that the order of four substrates hydrolyzed by AChE from C. kiinensis was acetyl- thiocholine iodide （ATCh） 〉β-metylthiocholine iodide （β-MTCh） 〉 propionylthiocholine iodide （PrTCh） 〉 butyrylthiocholine iodide （BuTCh）, the maximum velocity （ Vmax ） of AChE hydrolyzing ATCh was the highest among the four substrates, and the Vmax values were 0. 169 umol min^-1 mg^-1. Compared to organophosphates, the inhibition potential of carbamates was higher. The sensitivity of AChE to carbofuran was the highest among the two kinds of inhibitors, and its I50 value was 1× 10^-8 mol L^-1. The inhibitory tendencies of the two cholinesterase inhibitors to AChE were very similar, and their inhibition abilities in- creased with time. It was suggested that the ATCh was the optimal substrate of ACHE, and AChE from C. kiinensis was more sensitive to low concentration of organophosphate and carbamate insecticides in vitro. Fig 2, Table 2, Ref 23