| Permanganate Oxidation of α-Amino Acids: Kinetic Correlations for the Non-Autocatalytic and Autocatalytic Reaction Pathways. | |
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MedLine Citation:
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PMID: 21793513 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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The reactions of permanganate ion with seven α-amino acids in aqueous KH2PO4-K2HPO4 buffers have been followed spectrophotometrically at two different wavelengths: 526 nm (decay of MnO4 - ) and 418 nm (formation of colloidal MnO2). All the reactions studied were autocatalyzed by colloidal MnO2, the contribution of the autocatalytic reaction pathway decreasing in the order glycine > L-threonine > L-alanine > L-glutamic acid > L-leucine > Lisoleucine > L-valine. The rate constants corresponding to the non-autocatalytic and autocatalytic pathways have been obtained by means of either a differential rate law or an integrated one, the latter requiring the use of an iterative method for its implementation. The activation parameters for the two pathways have been determined and analyzed in order to obtain statistically significant correlations for the series of reactions studied. The activation enthalpy of the non-autocatalytic pathway showed a strong, positive dependence on the standard Gibbs energy for the dissociation of the protonated amino group of the α-amino acid. Linear enthalpy-entropy correlations were found for both pathways, leading to isokinetic temperatures of 370 ± 21 K (non-autocatalytic) and 364 ± 28 K (autocatalytic). Mechanisms in agreement with the experimental data are proposed for the two reaction pathways. |
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Authors:
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Joaquin F Perez-Benito |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-7-27 |
Journal Detail:
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Title: The journal of physical chemistry. A Volume: - ISSN: 1520-5215 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: 9890903 Medline TA: J Phys Chem A Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
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