Pulse-radiolysis Study of the Reaction of Nitric Oxide with Superoxide

Article abstract of DOI:10.1039/DT9950002885

Using the pulse-radiolysis technique, nitric oxide (NO) was produced by the reaction of an hydrated electron with NO2(1-).This was verified by the formation of the NO complex of iron(II) myoglobin (Mb) after pulse radiolysis of iron(III) myoglobin in the presence of NO2(1-) under anaerobic conditions.By employing thsi technique, the reaction of superoxide (O2(1-)) with NO was followed directly in an axygen-saturated solution containing NO2(1-).It was found that O2(1-) reacted with NO with a second-order rate constant of 3.8E9 dm³ mol^-1 s^-1 at pH 7.5 to form oxoperoxonitrate(III) which has an absorption maximum around 300 nm.Oxoperoxonitrate(III) thus formed decomposed with a first-order rate constant of 0.8 s^-1 at pH 7.5.A similar decay process was observed in the reaction of O2(1-) with NO by monitored stopped-flow, where one part KO2 in dimethyl sulfoxide was mixed with nine parts of a NO-saturated solution in water.The formation of oxoperoxonitrate(III) was complete within the dead-time of the stopped-flow system.

Full text of DOI:10.1039/DT9950002885

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