Stereoselective covalent binding of enantiomers of anti-benzo[a]pyrene diol epoxide to DNA as probed by optical detection of magnetic resonance

Phosphorescence and optical detection of magnetic resonance measurements applied to the covalent adducts of (+)- and (-)-anti-benzo[a]pyrene with DNA show a marked red shift of the pyrenyl phosphorescence and a lowering of the zero field splitting parameters of the (-) adduct, relative to the (+) adduct and the (solvent-exposed) benzo[a]pyrene tetraol. These results are consistent with a predominance of quasi-intercalative sites in the (-) adduct and external, solvent-exposed sites in the (+) adduct.