CATALASE CATALYZES OF PEROXYNITRITE-MEDIATED PHENOLIC NITRATION

Catalase catalyzed the peroxynitrite-mediated nitration of 4-hydroxyph enylacetic acid. The curve for the pH dependence of nitration was simi lar to that for the reaction between peroxynitrite and phenol. Cyanide , azide, and 3-amino-1,2,4-triazole inhibited the nitration in a dose- dependent way, When catalase was mixed with peroxynitrite, Compound I was detected as an intermediate. Because azide was an electron donor f or the peroxidatic action of catalase, and because 3-amino-1,2,4-triaz ale inhibited catalase activity by binding with Compound I, peroxynitr ite-mediated phenolic nitration was probably accompanied by Compound I formation, Both catalase and superoxide dismutase protected Escherich ia coli from peroxynitrite toxicity.