Author/Editor		Stojan, Jure; Marcel, Veronique; Fournier, Didier
Title		Inhibition of Drosophila acetylcholinesterase by 7-(methylethoxyphosphinyloxy)1-methyl-quinolinium iodide (MEPQ)
Type		članek
Source		Chem Biol Interact
Vol. and No.		Letnik 119-120
Publication year		1999
Volume		str. 147-57
Language		eng
Abstract		The kinetic behaviour of Drosophila Melanogaster acetylcholinesterase toward its substrate shows, in comparison with classic Michaelis-Menten kinetics, an apparent homotropic cooperative double activation-inhibition pattern. In order to construct an appropriate kinetic model and obtain further information on the mechanism of the catalytic action of this enzyme, the hydrolysis of acetylthiocholine in the absence and presence of different concentrations of synthetic quaternary methylphosphonate MEPCa was followed on a stopped-flow apparatus. The reaction at low substrate concentrations was followed until the change of the absorbance became negligible and at high concentrations only initial parts were recorded. A simultaneous analysis of the progress curves using numerical integration showedi that the powerful organophosphonate inhibitor binds and compete with the substrate for the same binding sites. The results are also in accordance with the hypothesis that virtually every substrate or quasi-substrate molecule that enters into the gorge of active site is hydrolysed.
Descriptors		CHOLINESTERASE INHIBITORS ACETYLCHOLINESTERASE QUINOLINIUM COMPOUNDS ACETYLCHOLINE BRAIN HYDROLYSIS MODELS, CHEMICAL MODELS, MOLECULAR PHOSPHORYLATION DROSOPHILA MELANOGASTER