Construction of peptide conjugates with peptide nucleic acids containing an anthracene probe and their interactions with DNA Original Research Article

We designed and synthesized the peptide nucleic acid (PNA)–peptide conjugates having anthracene chromophores and investigated their interactions with calf thymus DNA, [d(AT)10]2, [d(GC)10]2, and [d(AT)10dA6]2. Considering the synthesis compatibility and expecting that a novel DNA analogue, PNA, can improve DNA binding properties of α-helix peptides, we attempted to attach thymine PNA oligomers at the C-terminus of a 14 amino acid α-helix peptide that contained a pair of artificial intercalators, anthracene, as a probe, and to examine their interactions with DNA using anthracene UV, fluorescence and circular dichroism properties. The results observed in this study showed that the designed peptide folded in an α-helix structure in the presence of calf thymus DNA, [d(AT)10]2, and [d(AT)10dA6]2 with the chromophores at the side-chain being fixed with a left-handed chiral-sense orientation. The α-helix and the anthracene signals were not observed for [d(GC)10]2. Incorporation of thymine PNA oligomers into the designed α-helix peptide increased the DNA binding ability to [d(AT)10dA6]2 with increasing the length of the PNA without changing the conformations of the peptide backbone and the anthracene side-chains.