Mutational Spectra for 5,6-Dimethylchrysene 1,2-Dihydrodiol 3,4-Epoxides in the supF Gene of pSP189

Dihydrodiol epoxides from 5,6-dimethylchrysene exhibit properties similar to those of fjord region-containing hydrocarbon derivatives in that they react extensively with deoxyadenosine residues in DNA and consequently generate substantial numbers of mutations at AT pairs as well as GC pairs. The syn-dihydrodiol epoxide favors reaction with deoxyadenosine (68% of adducts) to a greater extent than does the anti-dihydrodiol epoxide (52% of adducts), and point mutations at AT pairs (72% for syn- and 45% for anti-dihydrodiol epoxide) follow the same trend. A novel feature of the mutagenicity of the 5,6-dimethylchrysene derivatives is that they exhibit a higher fraction of AT → GC transitions (28% and 26% for syn and anti, respectively) than has been seen for other hydrocarbon derivatives to date.