Binding of K- and Non-K-Region Arene Oxides and Phenols of Polycyclic Hydrocarbons to Polyguanylic Acid¹

Arene oxide derivatives of carcinogenic polycyclic hydrocarbons have been postulated as the reactive intermediates responsible for the in vivo binding of the parent hydrocarbon to cellular nucleic acids. In this study the reaction of 12 different K- and non-K-region arene oxides and 7 benzo(a)pyrene phenols with polyguanylic acid in aqueous acetone solutions has been investigated. The extent of binding of the polycyclic hydrocarbon was monitored by changes in the ultraviolet absorption and fluorescence spectra of the reisolated polyguanylic acid. The most reactive compound was the K-region arene oxide of 7,12-dimethylbenz(a)anthracene. A lower but significant level of binding was detected with the K-region arene oxides of benz(a)anthracene, benzo(a)pyrene, and 3-methylcholanthrene. Very low or negligible binding was detected with the K-region arene oxides of pyrene and phenanthrene; the non-K-region arene oxides of benzo(a)pyrene, phenanthrene, and naphthalene; and all of the benzo(a)pyrene phenols. Significant differences in the fluorescence spectra of polyguanylic acid modified with three different benzo(apyrene arene oxides were observed.