Recognition of a guanine-cytosine base pair by 8-oxoadenine

The interaction of two oligodeoxyribonucleotides, I(A) and II(A), with the duplex deoxyribonucleotide III-IV(Y-Z) was studied. The results of continuous variation experiments, melting experiments and circular dichroism spectroscopy show that I(A) and II(A) each form triplexes with III-IV(Y-Z) at neutral and basic pH. Moreover, it appears that 8-oxoadenine residue in the two oligodeoxyribonucleotides interacts in a specific manner with G-C base pairs of the duplex.