Effects of carbon dioxide/bicarbonate on induction of DNA single‐strand breaks and formation of 8‐nitroguanine, 8‐oxoguanine and base‐propenal mediated by peroxynitrite

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Abstract
Carbon dioxide has been reported to react with peroxynitrite (ONOO−), a strong oxidant and nitrating agent, to form an ONO2CO2 − adduct, altering the reactivity characteristic of peroxynitrite. We found that bicarbonate (0–10 mM) caused a dose‐dependent increase of up to 6‐fold in the formation of 8‐nitroguanine in calf‐thymus DNA incubated with 0.1 mM peroxynitrite, whereas it produced no apparent effect on 8‐oxoguanine formation. In contrast, bicarbonate inhibited peroxynitrite‐induced strand breakage in plasmid pBR322 DNA and thymine‐propenal formation from thymidine. We conclude that reacts with peroxynitrite to form a potent nitrating agent, but also to inactivate hydroxyl‐radical‐like activity of peroxynitrous acid.