Document Detail


Oxygen binding to partially nitrosylated hemoglobin.
MedLine Citation:
PMID:  23624264     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Reactions of nitric oxide (NO) with hemoglobin (Hb) are important elements in protection against nitrosative damage. NO in the vasculature is depleted by the oxidative reaction with oxy Hb or by binding to deoxy Hb to generate partially nitrosylated Hb (Hb-NO). Many aspects of the formation and persistence of Hb-NO are yet to be clarified. In this study, we used a combination of EPR and visible absorption spectroscopy to investigate the interactions of partially nitrosylated Hb with O2. Partially nitrosylated Hb samples had predominantly hexacoordinate NO-heme geometry and resisted oxidation when exposed to O2 in the absence of anionic allosteric effectors. Faster oxidation occurred in the presence of 2,3-diphosphoglycerate (DPG) or inositol hexaphosphate (IHP), where the NO-heme derivatives had higher levels of pentacoordinate heme geometry. The anion-dependence of the NO-heme geometry also affected O2 binding equilibria. O2-binding curves of partially nitrosylated Hb in the absence of anions were left-shifted at low saturations, indicating destabilization of the low O2 affinity T-state of the Hb by increasing percentages of NO-heme, much as occurs with increasing levels of CO-heme. Samples containing IHP showed small decreases in O2 affinity, indicating shifts toward the low-affinity T-state and formation of inert α-NO/β-met tetramers. Most remarkably, O2-equilibria in the presence of the physiological effector DPG were essentially unchanged by up to 30% NO-heme in the samples. As will be discussed, under physiological conditions the interactions of Hb with NO provide protection against nitrosative damage without impairing O2 transport by Hb's unoccupied heme sites. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.
Authors:
Angela Fago; Alvin L Crumbliss; Michael P Hendrich; Linda L Pearce; Jim Peterson; Robert Henkens; Celia Bonaventura
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2013-04-25
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1834     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2013 Sep 
Date Detail:
Created Date:  2013-07-29     Completed Date:  2013-09-26     Revised Date:  2014-09-02    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  1894-900     Citation Subset:  IM    
Copyright Information:
Copyright © 2013 Elsevier B.V. All rights reserved.
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MeSH Terms
Descriptor/Qualifier:
2,3-Diphosphoglycerate / metabolism
Electron Spin Resonance Spectroscopy
Heme / metabolism*
Hemoglobin A, Glycosylated / chemistry,  metabolism*
Humans
Nitric Oxide / chemistry,  metabolism*
Oxidation-Reduction
Oxygen / metabolism*
Oxyhemoglobins / metabolism*
Phytic Acid / metabolism
Protein Binding
Grant Support
ID/Acronym/Agency:
HL61411/HL/NHLBI NIH HHS; NS06732/NS/NINDS NIH HHS; R01 GM077387/GM/NIGMS NIH HHS; R01 HL061411/HL/NHLBI NIH HHS; U01 NS063732/NS/NINDS NIH HHS
Chemical
Reg. No./Substance:
0/Hemoglobin A, Glycosylated; 0/Oxyhemoglobins; 0/hemoglobin A, glycosylated-nitric oxide complex; 138-81-8/2,3-Diphosphoglycerate; 31C4KY9ESH/Nitric Oxide; 42VZT0U6YR/Heme; 7IGF0S7R8I/Phytic Acid; S88TT14065/Oxygen
Comments/Corrections

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