Tissue distribution, kinetic characters and sensitivity to insecticides of acetylcholinesterase in Oreochromis aurea

Acetylcholinesterase (AChE, EC3.1.1.7) plays an important role in environmental insecticide detection. Using muscle, liver and brain tissue as materials, tissue distribution and kinetic characters of acetylcholinesterase in Oreochromis aurea and its sensitivity to 12 kinds of insecticides (including 9 organophosphates,3 carbamates) were studied. The results showed that, brain tissue had the highest specific activity (1.34 mol/minmg) while the lowest protein content. Km of AChE in brain tissue was the minimal with 0.160 mmol/L, Km of AChE in muscle was second with 0.227 mmol/L, and Km of AChE in liver was the highest with 0.902 mmol/L. Vmax of AChE in brain tissue was the highest with 2.35 mol/minmgp, followed by liver tissue, and then muscle tissue with 0.63mol/minmgp. Inhibition test showed that 12 insecticides exhibited strong inhibitions on AChE with the order inmuscle tissue as dichlorvos > phoxim > dipterex > furadan > rogor > isofenphosmethyl > malathion > omethoate>carbosulfan > methamidophos > parathion > methomyl, the order in brain tissue as dichlorvos > furadan > methomyl> dipterex > phoxim > omethoate > rogor > parathion > carbosulfan > isofenphosmethyl > malathion > methamidophos, the order in liver tissue as furadan > dichlorvos > phoxim > isofenphosmethyl > methomyl > dipterex> omethoate> carbosulfan > parathion > malathion >methamidophos>rogor