Abstract
Nitrosative deamination of cytosine and adenine exclusively results in uracil (U) and hypoxanthine (Hx), respectively, whereas that of guanine lead to formation of xanthine (Xan) and oxanine (Oxa). The resulting U, Hx and Xan are excised from DNA by specific DNA glycosylases that hydrolyze the N-glycosidic bond. However, DNA glycosylases tested so far exhibit no or only marginal activity for Oxa, indicating that Oxa is a long persisting lesion. We have recently shown that Oxa forms covalent adducts with polyamines and DNA binding protein such as histone and DNA glycosylases. In the present study, we assessed the repair mechanism of a crosslink product formed between of Oxa and a cellular polyamine (spermine). A duplex oligonucleotide substrate containing an Oxa-spermine crosslink at the defined position was prepared and tested for purified repair enzymes and E. coli cell free extracts. The results will be presented in the meeting. [J Radiat Res 44:436 (2003)]
