Hybridization Studies with Chiral Peptide Nucleic Acids

A novel class of chiral peptide nucleic acids has been synthesized in which the sugar-phosphate backbone of DNA has been replaced with the glycyl-proline backbone of both theL- and theD-configurations, nucleobases being attached through the 4-position of proline withcis- andtrans-stereochemistry. TheT10homopolymers withcis-stereochemistry in theL- andD-series bind strongly to poly(dA) withTmvalues of 69 and 70°C, respectively. They bind more strongly to poly(rA) withTmvalues of 73 and 72°C, respectively, and with apparent 1:1 stoichiometry. Using a mixed sequence decamer it was found that the thermal stability of the chiral peptide nucleic acid/oligonucleotide complex was comparable to that formed by Nielsenʹs polyamide nucleic acid.