The use of thioglycollate to demonstrate DNA AP (apurinic/apyrimidinic-site) lyase activities. Biological consequences of thiol addition to the 5′ product of a β-elimination reaction at an AP site in DNA

Abstract

Thioglycollate reacts with the 5′ product of AP lyase activity on apurinic/apyrimidinic (AP) sites in DNA. The 3′-terminal thioglycollate-unsaturated sugar 5-phosphate adduct can be released by the use of Escherichia coli endonuclease IV or endonuclease VI, and identified by DEAE-Sephadex chromatography. In contrast, the mammalian AP endonuclease is unable to excise a 3′-terminal thiol-unsaturated sugar adduct; this lesion, which must sometimes occur in vivo, might be irreparable and have pathological consequences.