The conversion of benzo(alpha)pyrene 4,5-oxide into 4-hydroxybenzo(alpha)pyrene in the presence of polyriboguanylic acid.

Incubation of benzoalpha] pyrene 4,5-oxide with poly(G) in neutral aqueous ethanol resulted in the formation of covalent adducts and in the production of free 4-hydroxybenzoalpha]pyrene. This phenol, which was identified by its UV spectral properties and by its chromatographic characteristics, was also formed but at a much slower rate when the epoxide was incubated with DNA or with GMP. Phenol formation was not detected when benzoalpha]-pyrene 4,5-oxide was incubated for prolonged periods in the presence of poly(A), poly(C) or poly(U) or in the absence of nucleic acid. Formation of 4-hydroxybenzoalpha] pyrene from the epoxide in the presence of poly(G) was not accompanied by detectable base modifications or by breakage of phosphodiester linkages.