The laser excited fluorescence-line-narrowed spectrum of DNA modified with (+/-)-r-7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE), the ultimate carcinogenic metabolite of benzo[a]pyrene (BP), has been obtained in a water-glycerol-ethanol glass at 4.2 K. The spectrum was well resolved and highly characteristic of the chromophore. Comparisons were made between the spectrum of this modified DNA and the isolated deoxyguanosine-BPDE adduct and a series of other 7,8,9,10-tetrahydro-BP (THBP) derivatives. 9-Hydroxy-BP 4,5-oxide, which is also involved in the binding of BP to DNA, and THBP have very similar conventional broadband fluorescence spectra. However, the fluorescence-line-narrowed spectra of their derivatives were readily distinguishable either as individual components or as mixtures.

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