Conversion of a powerful frameshifter acridine to a base-pair substitution analog

The frameshift mutagenic mechanism for acridines has been attributed to the intercalative type of association between acridines and nucleic acids. However, it appears that these molecular details are insufficient to explain the frameshifting process. In order to design an effective drug probe to analyze the in vivo interactions of acridines leading to frameshifting, an azide analog of 9-aminoacridine was studied in Ames' Salmonella strains. The surprising findings were that by substituting an amino group at the 9 ring position with an azido group, the mutagenicity was converted from frameshifter to base-pair substitution.