Formation of 8‐nitroguanine in DNA treated with peroxynitrite in vitro and its rapid removal from DNA by depurination

Abstract

Peroxynitrite is a strong oxidant formed by reaction of nitric oxide with superoxide in inflamed tissues. We have demonstrated that 8-nitroguanine is formed dose-dependently in calf thymus DNA incubated with low concentrations of peroxynitrite in vitro. 8-Nitroguanine in acid-hydrolyzed DNA was chemically reduced into 8-aminoguanine, which was analyzed using high performance liquid chromatography with electrochemical detection. Only peroxynitrite, but not nitrite, tetranitromethane nor NO-releasing compounds, formed 8-nitroguanine. Antioxidants and desferrioxamine inhibited the reaction. 8-Nitroguanine was depurinated from DNA incubated at pH 7.4, 37°C (tu2 = -4 h). Peroxynitrite did not increase 8-oxoguanine levels in DNA.

Tyrosine‐nitration of caspase 3 and cytochrome c does not suppress apoptosis induction in squamous cell carcinoma cells

“…22,23 The impairment of proteins and DNA by ONOO Ϫ has been studied thoroughly. [15][16][17][18][19] In addition, ONOO Ϫ induces nitration of proteins and DNA. Many investigators have reported that nitration of tyrosine residues impaired the function of the protein by suppressing the phosphorylation of the protein and decreasing the enzyme activity.…”

“…13,14 The reactant ONOO Ϫ vigorously damages cells by impairment of proteins and DNA. [15][16][17][18][19] Inactivation of the proapoptotic proteins by ONOO Ϫ is therefore probable in chemoradiotherapy of cancers although the apoptosis-inducing activity of ONOO Ϫ has been demonstrated in multiple kinds of cancer cells. 20,21 NO reacts with molecular oxygen (O 2 ), O 2 Ϫ and transitional metals, yielding nitrogen dioxide (NO 2 ), ONOO Ϫ and metalnitrosyl adducts, respectively.…”

“…28 In these modifications, tyrosine nitration has been extensively explored with the aim of analysis of the cytotoxic mechanism of ONOO Ϫ . [15][16][17]29 A few investigators reported nitration of cytochrome c and s-nitrosylation of caspase 3 by ONOO Ϫ , but they did not examine the influence of nitration on the catalytic and proteolytic activities of these proteins. 30 -32 Cytochrome c and procaspase 3 have 4 and 10 tyrosine residues, respectively.…”

Free Radicals: Properties, Sources, Targets, and Their Implication in Various Diseases

“…8-nitroguanine formed is unstable and can be spontaneously removed, resulting in the formation of an apurininc site [75]. Conversely adenine can be paired with 8-nitroguanine during DNA synthesis resulting in a G-T transversions [76].…”

Overt Increase of Oxidative Stress and DNA Damage in Murine and Human Colitis and Colitis-Associated Neoplasia

“…As a consequence, nucleotides can be oxidized (such as guanine to 8-oxoG) resulting in base transversion (GC-TA), abasic sites and DNA single-and double-strand breaks. (7)(8)(9)(10)(11)(12) For cellular integrity, DNA double-strand breaks (DSB) can be fatal and their repair is initiated by the cellular DNA damage response (DDR) consisting of a multi-protein signalling cascade. (13,14) An early event in DSB response is phosphorylation of the H2A subtype histone H2AX at ser-139 (also known as γH2AX) by the phosphatidylinositol 3-like kinases ATM, ATR and DNA-PK.…”