Catalytic Peroxidation of Nitrogen Monoxide and Peroxynitrite by Globins

Globins are generally considered as carriers of diatomic gaseous ligands (e.g., O-2 and NO) in metazoa. Recently, the (pseudo-)enzymatic activity of globins towards reactive nitrogen and oxygen species has been elucidated. In particular, some globins (e.g., hemoglobin and myoglobin) catalyze the enzymatic scavenging of NO and peroxynitrite in the presence of H2O2. Indeed, H2O2 oxidizes some globins leading to the formation of water and of the heme-protein ferryl derivative, which, in turn, oxidizes NO and peroxynitrite leading to the formation of the globin ferric species, NO2-, and NO3-. Here, we hypothesize that NO, peroxynitrite, and H2O2 are co-substrates for the peroxidase activity of some globins, this catalytic activity was reported in 1900 for the first time, even though the substrates have never been identified firmly up to now. (C) 2008 IUBMB