Effects of an abasic site on triple helix formation characterized by affinity cleaving

Abstract
The stability of triple helical complexes of pyrimidine oligodeoxyribonucleotides containing one abasic 1,2- dideoxy-D-ribose (ø) residue was examined by affinity cleaving. Within a pyrimidine third strand, the triplets ø·AT, ø·GC, ø·TA and ø·CG are significantly less stable than the triplets, T- AT, C + GC and GTA. The decrease in binding produced by an abasic residue is similar to that observed with imperfectly matched natural base triplets, with ø · AT and ø · GC being less stable than ø · TA and ø · CG triplets for the sequences studied.