The mutagenicity of benzimidazole and benzimidazole derivatives. II. Incorporation of benzimidazole into the nucleic acids of Escherichia coli

The mutagenicity of benzimidazole has been attributed to base substitutions. These were believed to be the result of a small incorporation of benzimidazole—instead of a natural base—into nucleic acids. By using a new indirect method of radioactive labelling it has been possible to prove that benzimidazole is incorporated as such. This method involves growing bacteria in a medium containing radioactive phosphate and sufficient benzimidazole to guarantee optimal incorporation. Upon electrophoretic separation of the nucleotides resulting from the hydrolysis of the nucleic acids an additional phosphorus-containing compound was found and subsequently identified by comparison with an enzymatically synthesized benzimidazole mononucleotide.