Document Detail


The "neutral" hydrolysis of simple carboxylic esters in water and the rate enhancements produced by acetylcholinesterase and other carboxylic acid esterases.
MedLine Citation:
PMID:  21793525     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Because the heat of activation of the "neutral" (or uncatalyzed) hydrolysis of the neuro-transmitter acetylcholine exceeds the heats of activation of the acid- and base-catalyzed reactions, experiments at elevated temperatures permit evaluation of the rate constant and thermodynamic activation parameters of the neutral reaction in water at ordinary temperatures. At 25 °C, the extrapolated rate constant for the uncatalyzed (or neutral) hydrolysis of acetylcholine is 3.9 x 10^-7 s^-1 at 25 °C (ΔH‡ = 20.0 kcal/mol; TΔS‡ = -6.1 kcal/mol). Acetylcholine is more susceptible to neutral and base-catalyzed hydrolysis than ethyl acetate, but less susceptible to acid-catalyzed hydrolysis. For acetylcholinesterase from the electric eel, the catalytic proficiency [(kcat/Km)/kneutral] is 2 x 10^16 M-1, comparable in magnitude with the catalytic proficiencies of aminohydrolases that act on peptides and nucleosides.
Authors:
Richard V Wolfenden; Yang Yuan
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-7-27
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  -     ISSN:  1520-5126     ISO Abbreviation:  -     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-7-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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