Solution conformation of (AF)dG opposite a -2 deletion site in a DNA duplex: intercalation of the covalently attached aminofluorene ring into the helix with base displacement of the C8-modified syn guanine and adjacent unpaired 3'-adenine into the major groove

The aminofluorene ring of aminofluorene-C8-deoxyguanosine ({AF}dG) is intercalated between the Watson-Crick dC5.dG18 and dC8.dG17 base pairs. The deoxyguanosine base of (AF)dG, positioned in the major groove, shows a syn alignment. The solution conformation of (AF)dG adduct opposite a -2 deletion site indicates the involvement of stabilizing interactions. The base displacement and carcinogen-base stacking are comparable to the solution conformation of (AF)dG adduct opposite a -1 deletion site.