THE FORMATION OF BOTH APURINIC APYRIMIDINIC SITES AND SINGLE-STRAND BREAKS BY CHROMATE AND GLUTATHIONE ARISES FROM ATTACK BY THE SAME SINGLE REACTIVE SPECIES AND IS DEPENDENT ON MOLECULAR-OXYGEN

The induction of apurinic/apyrimidinic sites (AP sites) and DNA single-strand breaks (SSB) by chromate and glutathione in isolated DNA was investigated using agents that cleave the DNA at AP sites (putrescine and exonuclease III). It was found that chromate/glutathione-induced AP sites contain free aldehyde groups, as cleavage by putrescine could be prevented by treatment with sodium borohydride. The formation of AP sites and SSB followed a very similar temporal pattern, suggesting that both lesions arise from attack by the same single reactive species deriving from chromate and glutathione. Furthermore, the induction of both lesions was found to be dependent on the presence of molecular oxygen.