Author/Editor		Stojan, Jure; Marcel, Veronique; Fournier, Didier
Title		Effect of tetramethylammonium, choline and edrophonium on insect acetylcholinesterase: test of a kinetic model
Type		članek
Source		Chem Biol Interact
Vol. and No.		Letnik 119-120
Publication year		1999
Volume		str. 137-146
Language		eng
Abstract		Cholinesterases display a non-Michaelian bohaviour with respect to substrate concentration. With the insect enzyme, there is an activation at low substrate concentrations and an inhibition at high concentrations. Previous studies allow us to propose a kinetic model involving a secondary non-productive binding site for the substrate. Unexprctedly, this secondary site has a very high affinity for the substrate when the enzyme is free. On the contrary, when the catalytic site of the enzyme is occupied a strong decrease of this affinity was observed. Moreover, a substrate molecule bound to the poripheral site results in a global decrease of the acylation and/or the deacylation step. Kinetic studies with three reversible inhibitors, tetramethylammonium, edrophonium and choline supported the kinetic model and enable its further refinement.
Descriptors		ACETYLCHOLINESTERASE CHOLINE CHOLINESTERASE INHIBITORS GANGLIONIC STIMULANTS NOOTROPIC AGENTS AMMONIUM COMPOUNDS BACULOVIRIDAE BINDING SITES CATALYSIS DROSOPHILA MODELS, BIOLOGICAL RECOMBINANT PROTEINS