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    Entropic and enthalpic components of catalysis in the mutase and lyase activities of Pseudomonas aeruginosa PchB

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    Issue Date
    2011-05-11
    Author
    Luo, Qianyi
    Meneely, Kathleen M.
    Lamb, Audrey L.
    Publisher
    American Chemical Society
    Type
    Article
    Article Version
    Scholarly/refereed, publisher version
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    Abstract
    The isochorismate-pyruvate lyase from Pseudomonas aeruginosa (PchB) catalyzes two pericyclic reactions, demonstrating the eponymous activity and also chorismate mutase activity. The thermodynamic parameters for these enzyme-catalyzed activities, as well as the uncatalyzed isochorismate decomposition, are reported from temperature dependence of kcat and kuncat data. The entropic effects do not contribute to enzyme catalysis as expected from previously reported chorismate mutase data. Indeed, an entropic penalty for the enzyme-catalyzed mutase reaction (ΔS‡ = -12.1 ± 0.6 cal/molK) is comparable to that of the previously reported uncatalyzed reaction, whereas that of the enzyme-catalyzed lyase reaction (ΔS‡ = -24.3 ± 0.6 cal/molK) is larger than that of the uncatalyzed lyase reaction (-15.77 ± 0.02 cal/molK) documented here. With the assumption that chemistry is rate-limiting, we propose that a reactive substrate conformation is formed upon loop closure of the active site and that ordering of the loop contributes to the entropic penalty for converting the enzyme substrate complex to the transition state.
    Description
    This document is the Accepted Manuscript version of a Published Work that appeared in final form in the Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/ja202091a.
    URI
    http://hdl.handle.net/1808/24376
    DOI
    https://doi.org/10.1021/ja202091a
    Collections
    • Molecular Biosciences Scholarly Works [581]
    Citation
    Luo, Q., Meneely, K. M., & Lamb, A. L. (2011). Entropic and enthalpic components of catalysis in the mutase and lyase activities of Pseudomonas aeruginosa PchB. Journal of the American Chemical Society, 133(18), 7229–7233. http://doi.org/10.1021/ja202091a

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    Contact KU ScholarWorks
    785-864-8983
    KU Libraries
    1425 Jayhawk Blvd
    Lawrence, KS 66045
    785-864-8983

    KU Libraries
    1425 Jayhawk Blvd
    Lawrence, KS 66045
    Image Credits
     

     

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