Benzo[c]phenanthrene 3,4-dihydrodiol 1,2-epoxide adducts in native and denatured DNA

High performance liquid chromatography/UV-absorption and 32P-postlabeling were used to quantitate adducts generated by reaction of the four configurationally isomeric benzo[c]phenanthrene 3,4-dihydrodiol 1,2-epoxides with native or denatured DNA in vitro. For both the 4R, 3S-dihydrodiol 2S,1R-epoxide and the 4S,3R-dihydrodiol 2S,1R-epoxide, the amount of product resulting from trans-opening of the epoxide ring by the exocyclic amino group of deoxyadenosine in denatured DNA was much less than the level found in native DNA, indicating that the native DNA structure probably intercalates the hydrocarbon residue in a fashion that promotes adenine reaction for 2S,1R-epoxides.