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Electron-paramagnetic resonance spectroscopy using N-methyl-D-glucamine dithiocarbamate iron cannot discriminate between nitric oxide and nitroxyl: implications for the detection of reaction products for nitric oxide synthase

Electron-paramagnetic resonance spectroscopy using N-methyl-D-glucamine dithiocarbamate iron cannot discriminate between nitric oxide and nitroxyl: implications for the detection of reaction products for nitric oxide synthase
Electron-paramagnetic resonance spectroscopy using N-methyl-D-glucamine dithiocarbamate iron cannot discriminate between nitric oxide and nitroxyl: implications for the detection of reaction products for nitric oxide synthase
Purified neuronal nitric oxide synthase (NOS) does not produce nitric oxide (NO) unless high concentrations of superoxide dismutase (SOD) are added, suggesting that nitroxyl (NO(-)) or a related molecule is the principal reaction product of NOS, which is SOD-dependently converted to NO. This hypothesis was questioned by experiments using electron paramagnetic resonance spectroscopy and iron N-methyl-D-glucamine dithiocarbamate (Fe-MGD) as a trap for NO. Although NOS and the NO donor S-nitroso-N-acetyl-penicillamine produced an electron paramagnetic resonance signal, the NO(-) donor, Angeli's salt (AS) did not. AS is a labile compound that rapidly hydrolyzes to nitrite, and important positive control experiments showing that AS was intact were lacking. On reinvestigating this crucial experiment, we find identical MGD(2)-Fe-NO complexes both from S-nitroso-N-acetyl-penicillamine and AS but not from nitrite. Moreover, the yield of MGD(2)-Fe-NO complex from AS was stoichiometric even in the absence of SOD. Thus, MGD(2)-Fe directly detects NO(-), and any conclusions drawn from MGD(2)-Fe-NO complexes with respect to the nature of the primary NOS product (NO, NO(-), or a related N-oxide) are invalid. Thus, NOS may form NO(-) or related N-oxides instead of NO.
nitric oxide, nitroxyl, EPR, nitric oxide synthase, superoxide dismutase, free radical
0891-5849
739-742
Komarov, Andrei M.
58da10bf-580f-48bf-9808-4574956601ad
Wink, David A.
008b5aec-8c2b-4035-8912-fb6fd530413c
Feelisch, Martin
8c1b9965-8614-4e85-b2c6-458a2e17eafd
Schmidt, Harald H.H.W.
28ef9449-82f1-4e55-b92c-7ed73f714513
Komarov, Andrei M.
58da10bf-580f-48bf-9808-4574956601ad
Wink, David A.
008b5aec-8c2b-4035-8912-fb6fd530413c
Feelisch, Martin
8c1b9965-8614-4e85-b2c6-458a2e17eafd
Schmidt, Harald H.H.W.
28ef9449-82f1-4e55-b92c-7ed73f714513

Komarov, Andrei M., Wink, David A., Feelisch, Martin and Schmidt, Harald H.H.W. (2000) Electron-paramagnetic resonance spectroscopy using N-methyl-D-glucamine dithiocarbamate iron cannot discriminate between nitric oxide and nitroxyl: implications for the detection of reaction products for nitric oxide synthase. Free Radical Biology & Medicine, 28 (5), 739-742. (doi:10.1016/S0891-5849(00)00156-8). (PMID:10754269)

Record type: Article

Abstract

Purified neuronal nitric oxide synthase (NOS) does not produce nitric oxide (NO) unless high concentrations of superoxide dismutase (SOD) are added, suggesting that nitroxyl (NO(-)) or a related molecule is the principal reaction product of NOS, which is SOD-dependently converted to NO. This hypothesis was questioned by experiments using electron paramagnetic resonance spectroscopy and iron N-methyl-D-glucamine dithiocarbamate (Fe-MGD) as a trap for NO. Although NOS and the NO donor S-nitroso-N-acetyl-penicillamine produced an electron paramagnetic resonance signal, the NO(-) donor, Angeli's salt (AS) did not. AS is a labile compound that rapidly hydrolyzes to nitrite, and important positive control experiments showing that AS was intact were lacking. On reinvestigating this crucial experiment, we find identical MGD(2)-Fe-NO complexes both from S-nitroso-N-acetyl-penicillamine and AS but not from nitrite. Moreover, the yield of MGD(2)-Fe-NO complex from AS was stoichiometric even in the absence of SOD. Thus, MGD(2)-Fe directly detects NO(-), and any conclusions drawn from MGD(2)-Fe-NO complexes with respect to the nature of the primary NOS product (NO, NO(-), or a related N-oxide) are invalid. Thus, NOS may form NO(-) or related N-oxides instead of NO.

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More information

Published date: March 2000
Keywords: nitric oxide, nitroxyl, EPR, nitric oxide synthase, superoxide dismutase, free radical
Organisations: Clinical & Experimental Sciences

Identifiers

Local EPrints ID: 337875
URI: https://eprints.soton.ac.uk/id/eprint/337875
ISSN: 0891-5849
PURE UUID: a3626fa5-5660-4c0e-82da-28b80abfd850
ORCID for Martin Feelisch: ORCID iD orcid.org/0000-0003-2320-1158

Catalogue record

Date deposited: 29 Jun 2012 10:31
Last modified: 06 Jun 2018 12:29

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