Chemically induced binding of the hepatocarcinogen N-monomethyl-4-aminoazobenzene to nucleic acids in vitro.

iodine. The data presented are consistent with the formation of a covalent linkage between MAB and DNA or RNA under these mild conditions. The covalently linked MAB cannot be extracted by organic solvents that remove the physically bound MAB from the nucleic acid. A chemical linkage was further indicated by gel filtration and equilibrium dialysis of the nucleic acid:MAB complexes. Hydrolysis of the persulfateinduced DNAor RNA-bound dye with deoxyribonuclease or alkali, phosphodiesterase, and alkaline phosphatase yields various nucleoside-bound dyes. The reaction of persulfate provides a new model system for a study of the activation mechanism of MAB in vitro.