Evaluation of base recognition abilities of 2'-deoxynucleoside N-oxide derivatives by polymerase reactions

The main products obtained by oxidation of cytosine and adenine bases with hydrogen peroxide are cytosine and adenine N-oxide derivatives. There is a possibility that these N-oxide derivatives are mutagenic in genomic DNA like 8-oxoguanine or thymine glycol. Although the chemical synthesis and properties of 2'-deoxynucleoside N-oxide derivatives have been well established, little has been reported about the chemical and biochemical behavior of oligodeoxynucleotides (ODNs) containing these modified 2'-deoxynucleoside. In this study, we examined their base recognition ability by DNA polymerase reactions. It was found that these modified derivatives were incorporated into the 3'-terminal site of an ODN by DNA polymerase selecting accurately the complementary G or T base on a template ODN. In the incorporation reaction using template ODNs containing 2'-deoxynucleoside N-oxide bases, their N-oxide bases were selectively recognized by the complementary 5'-triphosphate (dGTP or dTTP).