Studies of the binding of diolepoxide metabolites of polycyclic aromatic hydrocarbons to DNA using electrofluorescence polarization spectroscopy

In the electrofluorescence method, a solution of DNA with covalentlybound polycyclic hydrocarbons is placed in an electric field,and changes in the intensity of polarized fluorescence are observed.Under the correct conditions, these changes can be used to determinea value for the angle between the long axis of the hydrocarbonmolecule and the axis of the DNA helix. For DNA or poly(dA-dT)treated with each stereoisomer of anti-benzo[c]phenanthrenediolepoxide, ranged from 55° to 61°, consistent witha mixture of quasi-intercalated adenine adducts and externallybound guanine adducts. Similar results were obtained with anotherset of ‘fjord-region’ diolepoxides, derived frombenzo[c]chrysene. Adducts in DNA treated with diolepoxides derivedfrom chrysene, 5-methylchrysene or 6-methylchrysene gave of53°, so the predominant adducts are externally bound, probablyin the minor groove of DNA.