title: On the effect of oxygen or copper(II) in radiation-induced degradation of DNA in the presence of thiols.
abstract: Degradation of DNA when gamma-irradiated in aqueous solutions containing cysteine can be efficiently enhanced not only with oxygen, but to the same extent also with Cu2+ ions under hypoxic conditions. The result can be explained by 'self-repair' in this system due to recombination of DNA. with RSS.-R intermediates, and repair inhibition by oxygen or copper involving RSS.-R scavenging. It is emphasized that oxygen enhancement in DNA-thiol systems may occur not only by peroxidation, via defect fixation (DNA-O2.) or thiol activation (RS-O2.), but also by the well-established inactivation of RSS.-R by oxygen. There is evidence also from literature data for a correlation between oxygen enhancement and RSS.-R stability, which varies with thiol concentration, pH and thiol structure.
mesh_terms: D003300:Copper; D003545:Cysteine; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D010100:Oxygen; D011835:Radiation Protection; D012996:Solutions; D013438:Sulfhydryl Compounds; D014867:Water
chemical_list: D012996:Solutions; D013438:Sulfhydryl Compounds; D014867:Water; D003300:Copper; D004247:DNA; D003545:Cysteine; D010100:Oxygen