| The "neutral" hydrolysis of simple carboxylic esters in water and the rate enhancements produced by acetylcholinesterase and other carboxylic acid esterases. | |
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MedLine Citation:
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PMID: 21793525 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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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. |
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Authors:
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Richard V Wolfenden; Yang Yuan |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-7-27 |
Journal Detail:
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Title: Journal of the American Chemical Society Volume: - ISSN: 1520-5126 ISO Abbreviation: - Publication Date: 2011 Jul |
Date Detail:
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Created Date: 2011-7-28 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7503056 Medline TA: J Am Chem Soc Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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