Effect of single benzo[a]pyrene diol epoxide-deoxyguanosine adducts on the action of DNA polymerases in vitro.

Neither Sequenase 2.0 nor Klenow fragment were able to extend 12-mer primers using the eight templates (16-mers) derived by placing each of the four isomeric benzo[a]pyrene diol epoxide-deoxyguanosine adducts at the 13th nucleotide from the 3'-end of two different sequence contexts. Using an 11-mer primer to get a running start did not overcome the adduct induced block of primer extension except for the Klenow fragment and one of the two sequence contexts, indicating primer extension is dependent on both the polymerase and sequence context. In this case, purine nucleoside triphosphates (dATP>dGTP) were incorporated opposite each of the four adducts.