The reaction of nitric oxide with organic peroxyl radicals

Nitric oxide and organic peroxyl radicals are key reactive radicals implicated in a wide range of biological processes. We have measured rate constants for the reactions of several organic peroxyl radicals with nitric oxide in aqueous solution and found that they are all fast, with k = 1-3 x 10(9) L mol-1 s-1. The reactions lead to the formation of an intermediate, identified as the organic peroxynitrite, which decayed with a rate constant of k = 0.1-0.3 s-1. Possible products of this decay include the more reactive alkoxyl and nitrogen dioxide free radicals, or the less reactive organic nitrate. In alcoholic solutions, the rate constants of the initial reactions were similar, but the product decay rates were about 200 times faster. Because of the ubiquity of both nitric oxide and organic peroxyl radicals, their interaction could make a significant contribution to many physiological processes.