33] Kinetic analysis of reactivity of peroxynitrite with biomolecules

Abstract

Publisher Summary This chapter discusses the kinetic analysis of reactivity of peroxynitrite with biomolecules. The kinetics of peroxynitrite reactions with biomolecules provides clues to understand the reaction mechanism of peroxynitrite toward biomolecules and allows the prediction of the preferential fate of peroxynitrite in biological systems. Peroxynitrite anion (ONOO – ) is, in the absence of target molecules (S 1 ), a stable species that can be prepared and stored for several weeks at –80 ° in 1 N NaOH, without substantial loss. The isomerization of peroxynitrous acid to nitrate occurs through the intermediate formation of an energized species (ONOOH*) that is about 18 kcal/mol higher in energy than peroxynitrous acid in the ground state (ONOOH). The transition from ONOOH to ONOOH* is a slow step, being rate limiting in the proton catalyzed decomposition of peroxynitrite. Kinetic analysis shows that peroxynitrite may react with target molecules with more than one reaction mechanism and that the reactivity of peroxynitrite is strongly pH dependent.