Journal
NITRIC OXIDE-BIOLOGY AND CHEMISTRY
Volume 5, Issue 4, Pages 395-401Publisher
ACADEMIC PRESS INC
DOI: 10.1006/niox.2001.0365
Keywords
myoglobin; nitric oxide; nitrosoglutathione; reaction mechanism
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Ferrimyoglobin at pH 7.4 binds nitric oxide to yield nitric oxide adducts. In the presence of glutathione (GSH), nitrosoadducts of Mb(III) 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, k(GSH) = (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. (C) 2001 Academic Press.
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