| Kinetics and mechanism of the reduction of CrVI and CrV by D-lactobionic acid. | |
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MedLine Citation:
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PMID: 14729315 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The oxidation of D-lactobionic acid by Cr(VI) yields the 2-ketoaldobionic acid and Cr(3+) as final products when a 20-times or higher excess of the aldobionic acid over Cr(VI) is used. The redox reaction takes place through a complex multistep mechanism, which involves the formation of intermediate Cr(IV) and Cr(V) species. Cr(IV) reacts with lactobionic acid much faster than Cr(V) and Cr(VI) do, and cannot be directly detected. However, the formation of CrO(2)(2+), observed by the first time for an acid saccharide/Cr(VI) system, provides indirect evidence for the intermediacy of Cr(IV) in the reaction path. Cr(VI) and the intermediate Cr(V) react with lactobionic acid at comparable rates, being the complete rate laws for the Cr(VI) and Cr(V) consumption expressed by: -d[Cr(VI)]/dt=[k(I)+k(II)[H(+)]][lactobionicacid][Cr(VI)], where k(I)=(4.1+/-0.1) x 10(-3) M(-1) s(-1) and k(II)=(2.1+/-0.1) x 10(-2) M(-2) s(-1); and -d[Cr(V)]/dt=[k(III)[H(+)]+(k(IV)+k(V)[H(+)])[lactobionicacid]] [Cr(V)], where k(III)=(1.8+/-0.1) x 10(-3) M(-1) s(-1), k(IV)=(1.1+/-0.1) x 10(-2) M(-1) s(-1) and k(V)=(1.0+/-0.1) x 10(-2) M(-2) s(-1), at 33 degrees C. The Electron Paramagnetic Resonance (EPR) spectra show that five-co-ordinate oxo-Cr(V) bischelates are formed at pH 1-5 with the aldobionic acid bound to Cr(V) through the alpha-hydroxyacid group. |
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Authors:
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Viviana Roldán; Mabel Santoro; Juan C González; Juan Manuel Salas-Peregrin; Sandra Signorella; Luis F Sala |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Journal of inorganic biochemistry Volume: 98 ISSN: 0162-0134 ISO Abbreviation: J. Inorg. Biochem. Publication Date: 2004 Feb |
Date Detail:
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Created Date: 2004-01-19 Completed Date: 2004-09-23 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7905788 Medline TA: J Inorg Biochem Country: United States |
Other Details:
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Languages: eng Pagination: 347-57 Citation Subset: IM |
Affiliation:
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Departamento de Ciencias Básicas, Facultad de Ciencias Veterinarias, UNL, R.P. Kreder 735, Esperanza, Argentina. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Carcinogens, Environmental
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chemistry*,
metabolism Chromium / chemistry*, metabolism Disaccharides / chemistry*, metabolism Kinetics Oxidation-Reduction Spectrophotometry Spectrophotometry, Ultraviolet Time Factors |
| Chemical | |
Reg. No./Substance:
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0/Carcinogens, Environmental; 0/Disaccharides; 18540-29-9/chromium hexavalent ion; 7440-47-3/Chromium; 96-82-2/lactobionic acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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