Three chemically distinct types of oxidants formed by iron-mediated Fenton reactions in the presence of DNA.
AUTOR(ES)
Luo, Y
RESUMO
Exposure of Escherichia coli to H2O2 leads to two kinetically distinguishable modes of killing: mode I killing occurs maximally near 2 mM H2O2, whereas mode II killing is essentially independent of H2O2 concentrations up to 20 mM. A major portion of H2O2 toxicity is attributed to DNA damage caused by the iron-mediated Fenton reaction. By studying DNA damage during Fenton reactions in vitro, the same complex kinetics were observed and three types of oxidants were distinguished based upon their reactivities toward H2O2 and alcohols and upon iron-chelator effects. Type I oxidants are sensitive to H2O2 but moderately resistant to ethanol; type II oxidants are resistant to both H2O2 and ethanol; type III oxidants are sensitive to H2O2, ethanol, and t-butanol. To explain these results, we hypothesize that type I oxidants are generated upon Fe2+ associated with DNA only through electrostatic interactions and cause mode I killing of E. coli; type II oxidants arise upon Fe2+, which is at least partially base-associated, and cause mode II killing; type III oxidants arise on Fe2+ free in solution and probably do not cause killing. Therefore, particular interactions of DNA with transition metals should be considered to be an integral part of the chemistry and toxicity of H2O2.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=45453Documentos Relacionados
- Nucleosomal histone protein protects DNA from iron-mediated damage.
- Characterization of iron-mediated peroxidative injury in isolated hepatic lysosomes.
- Iron-Mediated Control of the Basic Helix-Loop-Helix Protein FER, a Regulator of Iron Uptake in Tomato1
- The second finger of Urbs1 is required for iron-mediated repression of sid1 in Ustilago maydis
- Iron-Mediated Degradation of IRP2, an Unexpected Pathway Involving a 2-Oxoglutarate-Dependent Oxygenase Activity