| The case of the missing NO-hemoglobin: spectral changes suggestive of heme redox reactions reflect changes in NO-heme geometry. | |
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MedLine Citation:
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PMID: 14514887 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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When low levels of gaseous nitric oxide (NO) are equilibrated with deoxygenated Hb, all NO added can be accounted for in terms of hexacoordinate and pentacoordinate forms of NO-Hb, despite recent reports on NO disappearance from heme groups to form nitroxyl anions or S-nitrosated Hb at low ratios of NO to Hb. We demonstrate that a fraction of the spectral signature of fully nitrosylated (largely hexacoordinate) Hb disappears as the pentacoordinate state forms and reappears when pentacoordinate NO-Hb is reconverted to the hexacoordinate condition. We show that the spectral changes associated with these reversible shifts in NO- heme geometry can be remarkably well approximated as variations in the contributions from fully nitrosylated Hb and oxidized Hb (MetHb). As a result, increases in the level of pentacoordinate NO-Hb that occur at low NO to Hb ratios can be misinterpreted as increases in MetHb levels associated with NO-dependent heme oxidation. Conversely, any decrease in levels of pentacoordinate NO-Hb can be misinterpreted as a disappearance of MetHb associated with NO-dependent heme reduction. Transitions between pentacoordinate and hexacoordinate forms of NO-Hb with spectral changes suggestive of changes in levels of heme-bound NO are sensitive to the protein's quaternary conformation and can be brought about by alterations in anion levels or the degree of heme saturation with either O2 or NO. |
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Authors:
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Angela Fago; Alvin L Crumbliss; Jim Peterson; Linda L Pearce; Celia Bonaventura |
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Publication Detail:
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Type: In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. Date: 2003-09-26 |
Journal Detail:
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Title: Proceedings of the National Academy of Sciences of the United States of America Volume: 100 ISSN: 0027-8424 ISO Abbreviation: Proc. Natl. Acad. Sci. U.S.A. Publication Date: 2003 Oct |
Date Detail:
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Created Date: 2003-10-15 Completed Date: 2003-12-04 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 7505876 Medline TA: Proc Natl Acad Sci U S A Country: United States |
Other Details:
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Languages: eng Pagination: 12087-92 Citation Subset: IM |
Affiliation:
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Nicholas School of the Environment and Earth Sciences, Duke University, Beaufort, NC 28516, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Electron Spin Resonance Spectroscopy Heme / chemistry*, metabolism* Hemoglobin A, Glycosylated / chemistry*, metabolism* Hemoglobins / chemistry, metabolism Humans Kinetics Methemoglobin / chemistry, metabolism Nitric Oxide / chemistry*, metabolism* Oxidation-Reduction Spectrophotometry |
| Grant Support | |
ID/Acronym/Agency:
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HL 58248/HL/NHLBI NIH HHS; HL 61411/HL/NHLBI NIH HHS; HL 71064/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Hemoglobin A, Glycosylated; 0/Hemoglobins; 0/hemoglobin A, glycosylated-nitric oxide complex; 10102-43-9/Nitric Oxide; 14875-96-8/Heme; 9008-02-0/deoxyhemoglobin; 9008-37-1/Methemoglobin |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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