FLUORESCENCE PROPERTIES OF A BENZO(A) PYRENE 7,8 DIHYDRODIOL 9,10-OXIDE-DNA ADDUCT - CONFORMATION AND EFFECTS OF INTER-MOLECULAR DNA INTERACTIONS

The pyrene-like fluorescence of the covalent benzo(a)pyrene diol-epoxide-DNA complex prepared by reacting 7,8,-dihydrodiol 9,10-epoxy benzo(a)pyrene (BPDE) with DNA in aqueous solution in vitro, has been investigated. It is shown that this fluorescence is sensitive to molecular oxygen, to the concentration of native DNA and to the ionic strength (KCl concentration), but is insensitive to the concentration of denatured DNA. These effects are related to the conformation of the pyrene-like chromophore of BPDE. Most of the fluorescence of a dilute solution of the DNA-bound benzo(a)pyrene derivative originates from binding sites in which the pyrene moiety is not intercalated between the DNA base pairs, but is located on the outside of the DNA double helix. © 1979.