Reaction Mechanism between Nitric Oxide and Glutathione Mediated by Fe(III) Myoglobin

Ferrimyoglobin at pH 7.4 binds nitric oxide to yield nitric oxide adducts. In the presence of glutathione (GSH), nitrosoadducts of MbIII react with it to give nitrosoglutathione, whose concentration has been determined with an apparatus based on a specific and sensitive solid-state amperometric gas...

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Bibliographic Details
Published in:Nitric oxide 2001-08, Vol.5 (4), p.395-401
Main Authors: Reichenbach, Gustavo, Sabatini, Stefano, Palombari, Roberto, Palmerini, Carlo A.
Format: Article
Language:English
Subjects:
Glutathione - chemistry
Glutathione - metabolism
Kinetics
Metmyoglobin - chemistry
Metmyoglobin - metabolism
myoglobin
Nitric Acid - chemistry
Nitric Acid - metabolism
nitric oxide
nitrosoglutathione
reaction mechanism
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Summary:Ferrimyoglobin at pH 7.4 binds nitric oxide to yield nitric oxide adducts. In the presence of glutathione (GSH), nitrosoadducts of MbIII react with it to give nitrosoglutathione, whose concentration has been determined with an apparatus based on a specific and sensitive solid-state amperometric gas sensor. The reaction constant between the adduct and glutathione, kGSH = (47 ± 1) M−1 s−1, obtained by UV-Vis spectroscopy kinetic measurements, is about one-eighth of the constant with OH− determined by other authors. We can explain this fact with the higher nucleophilicity of OH− compared to GSH, due to the bulkiness and charge of the species. It is known that the formation of nitrosothiols starting from nitrite or NO (nitrogen monoxide) and glutathione, in the absence of oxygen, is impossible. Thus, from a biological point of view, it is important to point out that GSH reacts with NO in the presence of ferrimyoglobin, even at physiological pH, to form nitrosoglutathione.
ISSN:1089-8603
1089-8611
DOI:10.1006/niox.2001.0365