Figure 5.
Position-specific effects of the trans-10R- and 10S-N6-BaP DE-2 dA adducts at position −1 in the lower strand. (A) Sequence of the oligonucleotides used and schematic representation of the intercalated BaP dA adducts (shaded rectangles). Labeling of the upper (scissile) strand with [α-32P]cordycepin is schematically represented as 32P-A. (B) top1-mediated DNA cleavage of the unadducted (control) oligonucleotide, and of the two oligonucleotides containing the BaP dA adduct at position −1 in the lower strand. Lanes 1, 4, and 6, unreacted oligonucleotides; lanes 2, 5, and 7, reactions performed in the presence of top1; lane 3, reactions performed in the presence of both top1 and camptothecin (10 μM). Reactions were for 30 min at 25°C.