| The reaction of Pseudomonas nitrite reductase and nitrite. A stopped-flow and EPR study. | |
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MedLine Citation:
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PMID: 2164015 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The reaction between reduced Pseudomonas nitrite reductase and nitrite has been studied by stopped-flow and rapid-freezing EPR spectroscopy. The interpretation of the kinetics at pH 8.0 is consistent with the following reaction mechanism (where k1 and k3 much greater than k2). [formula: see text] The bimolecular step (Step 1) is very fast, being lost in the dead time of a rapid mixing apparatus; the stoichiometry of the complex has been estimated to correspond to one NO2- molecule/heme d1. The final species is the fully reduced enzyme with NO bound to heme d1; and at all concentrations of nitrite, there is no evidence for dissociation of NO or for further reduction of NO to N2O. Step 2 is assigned to an internal electron transfer from heme c to reduced NO-bound heme d1 occurring with a rate constant of 1 s-1; this rate is comparable to the rate of internal electron transfer previously determined when reducing the oxidized enzyme with azurin or cytochrome c551. When heme d1 is NO-bound, the rate at which heme c can accept electrons from ascorbate is remarkably increased as compared to the oxidized enzyme, suggesting an increase in the redox potential of the latter heme. |
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Authors:
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M C Silvestrini; M G Tordi; G Musci; M Brunori |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 265 ISSN: 0021-9258 ISO Abbreviation: J. Biol. Chem. Publication Date: 1990 Jul |
Date Detail:
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Created Date: 1990-08-14 Completed Date: 1990-08-14 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 11783-7 Citation Subset: IM |
Affiliation:
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Department of Biomedical Sciences, University of L'Aquila, Italy. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Electron Spin Resonance Spectroscopy Kinetics Models, Theoretical NADH, NADPH Oxidoreductases / metabolism* Nitrite Reductases / metabolism* Nitrites / metabolism* Oxidation-Reduction Protein Binding Pseudomonas / enzymology* Time Factors |
| Chemical | |
Reg. No./Substance:
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0/Nitrites; EC 1.6.-/NADH, NADPH Oxidoreductases; EC 1.7.-/Nitrite Reductases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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