Author/Editor | Stojan, Jure; Brochier, Laure; Alies, Carole; Colletier, Jacques Philippe; Fournier, Didier | |
Title | Inhibition of Drosophila melanogaster acetylcholinesterase by high concentations of substrate | |
Type | članek | |
Source | Eur J Biochem | |
Vol. and No. | Letnik 271 | |
Publication year | 2004 | |
Volume | str. 1364-71 | |
Language | eng | |
Abstract | Acetylcholine hydrolysis by acetylcholinesterase is inhibited at high substrate concentrations. To determine the residues involved in this phenomenon, we have mutated most of the residues lining the active-site gorge but mutating these did not completely eliminate hydrolysis. Thus, we analyzed the effect of a nonhydrolysable substrate analogue on substrate hydrolysis and on reactivation of an analogue of the acetylenzyme. Analyses of various models led us to propose the following sequence of events: the substrate initially binds at the rim of the active-site gorge and then slides down to the bottom of the gorge where it is hydrolyzed. Another substrate molecule can bind to the peripheral site: (a) when the choline is still inside the gorge - it will thereby hinder its exit; (b) after choline has dissociated but before deacetylation occurs - binding at the peripheral site increases deacetylation rate but (c) if a substrate molecule bound to the peripheral site slides down to the bottom of the active-site before the catalytic serine is deacetylated, its new position will prevent the approach of water, thus blocking deacetylation. | |
Descriptors | DROSOPHILA MELANOGASTER ACETYLCHOLINESTERASE BINDING SITES ACETYLCHOLINE KINETICS ACETYLTHIOCHOLINE MUTAGENESIS, SITE-DIRECTED HYDROLYSIS SUBSTRATE SPECIFICITY |