Peptide nucleic acids containing adenine or guanine recognize thymine and cytosine in complementary DNA sequences

Peptide nucleic acid (PNA) monomer building blocks for the introduction of G and A are prepared and used to synthesise H-T4XT5-Lys-NH2(X = G or A), which are shown by Tm measurements to recognize their complementary DNA sequences in both the parallel (N-terminal PNA/5′-DNA) and the anti-parallel mode; the stoichiometry in each case is (PNA)2/DNA.