piperidines and sodium-borohydride

In Escherichia coli, endonuclease III (endo III) repairs the oxidation products of 8-OHGua. However, the corresponding repair enzymes in eukaryotes have not been identified. Here we report that 8-hydroxyguanine (8-OHGua) is highly sensitive to further oxidation. We also show that Ntg2, a functional homolog of endo III in Saccharomyces cerevisiae, is capable of nicking the irradiated duplex DNA containing 8-OHGua. Moreover, Ntg2 formed a stable complex with the DNA upon incubation with NaBH(4). In contrast, Ntg1, another functional homolog of endo III, showed no such activities. These findings indicate that Ntg2 is, at least in part, responsible for repairing the oxidation products of 8-OHGua in eukaryotic cells.

Topics: Borohydrides; Deoxyadenosines; Deoxycytidine; Deoxyguanosine; DNA; DNA-(Apurinic or Apyrimidinic Site) Lyase; DNA-Formamidopyrimidine Glycosylase; Dose-Response Relationship, Radiation; Escherichia coli Proteins; Gamma Rays; Guanine; Hydrogen Peroxide; Hydroxyl Radical; Iron; Macromolecular Substances; N-Glycosyl Hydrolases; Oxidation-Reduction; Piperidines; Protein Binding; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Substrate Specificity; Thymidine