Decay-associated emission spectra and other spectral evidence for the physical intercalation of 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene into DNA.
A benzo[a]pyrene derivative, 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene, forms physical complexes with DNA. The measured absorption spectrum of the hydrocarbon in the complex is shifted approximately 10 nm to the red and the fluorescence emission spectrum is red-shifted approximately 6 nm, characteristic of a physical intercalation complex. The decay-associated emission spectra of the hydrocarbon in the presence of DNA have been measured, thus providing a new technique to obtain information about the DNA binding sites. The decay-associated emission spectra of the free and bound hydrocarbons were obtained by deconvoluting the time-dependent emission at several wavelengths. Stern-Volmer plots with iodide and silver ions as quenchers suggest that at least one set of binding sites for the formation of a physical intercalation complex between the benzo[a]pyrene derivative and DNA is at guanine sites in the biopolymer.更多