REACTIVE INORGANIC OXY-SPECIES OF C, N, S, AND P - Oxidation of Amino Acids, Peptides, and Proteins: Kinetics and Mechanism - page 205

REACTIVE INORGANIC
OXY-SPECIES OF C, N, S, AND P
In the last two decades, reactive species such as carbonate radical anion, nitro-
gen dioxide, and peroxynitrite have received attention due to their important
role in cell homeostasis [1, 2]. The biological relevance of these species was
observed in the efficiency of classical antioxidants, such as urate and nitroxides,
in the protection of cells and the overall living organism against injuries
related to an overproduction of nitric oxide [3, 4]. The potential physiological
sources and biochemical reactions of the species are presented in Figure 5.1.
Several rate studies supported the scheme shown in Figure 5.1 [5-7]. High rate
constants for the reactions of the carbonate radical with biomolecules as the
potential cell target at physiological pH were determined (discussed below).
Thus, the carbonate radical can cause significant damage in vivo (Fig. 5.1).
Among the different carbon species, the toxicity of CO 2 has also been reviewed
[8]. Nitrogen dioxide can be produced from several physiological routes such
as nitric oxide auto-oxidation and peroxidase-catalyzed reactions [2]. The
selectivity of nitrogen dioxide with biomolecules is discussed below. The
studies on sulfate and phosphate radicals are also presented because of their
involvement in treating pollutants using advanced oxidation processes. More-
over, both sulfate and phosphate radicals are one-electron oxidants and are
precursors of organic radicals of biologically relevant molecules, such as pep-
tides. Additionally, the aqueous reactions of sulfate radicals are relevant to
atmospheric chemistry [9, 10].