Ten sulfur compounds (the compounds shown in Fig. 1 and oxidized glutathione) were examined using gel electrophoresis to determine their ability to prevent DNA damage by CuI/H2O2. Fig. 2 shows the effects of oxidized glutathione (GSSG) in inhibiting copper-mediated oxidative DNA damage. H2O2 alone does not damage DNA; however, combining CuII, ascorbate, and H2O2 results in 97% DNA damage (Fig. 2, lane 4). Addition of increasing concentrations of GSSG causes a substantial decrease in oxidative DNA damage as compared to lane 4, with 10 lM GSSG inhibiting 99% (p < 0.001) of DNA damage (Fig. 2, lane 9). Fig. 3 illustrates the best-fit dose–response curve for GSSG, demonstrating that the concentration of GSSG required to inhibit 50 % of copper-mediated oxidative DNA damage (IC50) is 6.6 ± 1.0 lM (Table 1). Similarly, the IC50 for reduced glutathione is 12.4 ± 1.0 lM, and GSH inhibited 97% of DNA damage at 30 lM (p < 0.001). Notably, these IC50 values are a thousand times less than the measured intracellular concentrations of glutathione (1–15 mM) [1,43].
Ten sulfur compounds (the compounds shown in Fig. 1 and oxidized glutathione) were examined using gel electrophoresis to determine their ability to prevent DNA damage by CuI/H2O2. Fig. 2 shows the effects of oxidized glutathione (GSSG) in inhibiting copper-mediated oxidative DNA damage. H2O2 alone does not damage DNA; however, combining CuII, ascorbate, and H2O2 results in 97% DNA damage (Fig. 2, lane 4). Addition of increasing concentrations of GSSG causes a substantial decrease in oxidative DNA damage as compared to lane 4, with 10 lM GSSG inhibiting 99% (p < 0.001) of DNA damage (Fig. 2, lane 9). Fig. 3 illustrates the best-fit dose–response curve for GSSG, demonstrating that the concentration of GSSG required to inhibit 50 % of copper-mediated oxidative DNA damage (IC50) is 6.6 ± 1.0 lM (Table 1). Similarly, the IC50 for reduced glutathione is 12.4 ± 1.0 lM, and GSH inhibited 97% of DNA damage at 30 lM (p < 0.001). Notably, these IC50 values are a thousand times less than the measured intracellular concentrations of glutathione (1–15 mM) [1,43].
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