Activity of carcinogens that bind to the C8 position of guanine residues in an assay specific for the detection of -2 frameshift mutations in a defined hot spot.

In this paper we describe a reversion assay specific for the detection of -2 frameshift mutations occurring within short stretches of alternating GC sequences. We have compared a series of chemical carcinogens that all bind covalently to the C8 position of guanine residues for their potency in inducing revertants in this assay. Large variations in potency are found within the list of compounds that were tested. The most potent chemicals tested induce the reversion frequency by a factor of 10(5) over background, whereas others only increase it by two orders of magnitude. These differences are discussed in terms of the conformational changes that the different C8-guanine adducts induce in DNA.