Document Detail


The reaction of Pseudomonas nitrite reductase and nitrite. A stopped-flow and EPR study.
MedLine Citation:
PMID:  2164015     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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.
Authors:
M C Silvestrini; M G Tordi; G Musci; M Brunori
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  265     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1990 Jul 
Date Detail:
Created Date:  1990-08-14     Completed Date:  1990-08-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  11783-7     Citation Subset:  IM    
Affiliation:
Department of Biomedical Sciences, University of L'Aquila, Italy.
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MeSH Terms
Descriptor/Qualifier:
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:
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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