Cell and microsome mediated binding of 7,12-dimethylbenz(a)anthracene to DNA studied by fluorescence spectroscopy

Fluorescence spectra of DNA isolated from hamster embryo cells incubated with 7,12-dimethylbenz(a)anthracene, or DNA modified in a microsomal system by reaction with this carcinogen or its 7-hydroxymethyl derivative, were compared to various model compounds. The spectra indicate that the DMBA derivative bound to DNA, in all 3 cases, has a 9,10-dimethylanthracene-like chromophore. They also provide the first evidence of the similarity in structure of the DNA-bound products between 7,12-dimethylbenz(a)anthracene and its 7-hydroxymethyl derivative. Our results are consistent with an activation mechanism that involves saturation of the 1,2,3,4-ring positions.