Reactions of heme peroxidases with peroxynitrite

The interaction of peroxynitrite, produced by ozonation of azide, with two heme peroxidases (horseradish peroxidase and lactoperoxidase) was studied. Enzymes retained full activity after incubation with peroxynitrite at neutr al pH, Lactoperoxidase alone was found to catalyze peroxynitrite decomposit ion, whereas horseradish peroxidase accelerated peroxynitrite decomposition only in the presence of certain substrates, For example, in the presence o f guaiacol the catalyzing effect was clear, but in the presence of trolox w as only noticeable.