Nitrite, a reactive nitrogen species, protects human alpha-2-macroglobulin from halogenated oxidant, HOCl.

Reactive nitrogen species have been implicated in the pathogenesis of over 40 human diseases, including inflammation. Evidences suggest that reactive nitrogen species such as nitrite/nitrate and halogenated oxidant-HOCl accumulate at the site of inflammation. At physiologically attainable concentrations, HOCl was found to significantly damage the antiproteolytic potential of human alpha(2)M and induce subtle changes in conformation as judged by fluorescence analysis. Our studies further suggest that at physiological concentrations, nitrite offered significant protection against HOCl induced alpha(2)M inactivation. Our studies suggest that nitrite may act as an antioxidant at physiological concentrations by removing HOCl at sites where both NO(2) and HOCl are formed.