Jure Stojan, Laure Brochier, Carole Alies, Jacques Philippe Colletier, Didier Fournier
{"title":"Inhibition of Drosophila melanogaster acetylcholinesterase by high concentrations of substrate.","authors":"Jure Stojan, Laure Brochier, Carole Alies, Jacques Philippe Colletier, Didier Fournier","doi":"10.1111/j.1432-1033.2004.04048.x","DOIUrl":null,"url":null,"abstract":"<p><p>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.</p>","PeriodicalId":11817,"journal":{"name":"European journal of biochemistry","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2004-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/j.1432-1033.2004.04048.x","citationCount":"42","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"European journal of biochemistry","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1111/j.1432-1033.2004.04048.x","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 42
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.