Aminoethylprolyl peptide nucleic acids (aepPNA): chiral PNA analogues that form highly stable DNA:aepPNA2 triplexes

[formula: see text] The replacement of the glycyl component in the peptide nucleic acid (PNA) backbone by a prolyl unit bearing a nucleobase leads to the aminoethylprolyl (aep) PNAs, which are chiral and cationic. The homooligomeric aepPNA binds to complementary DNA sequences with high affinity and sequence specificity, forming highly stable triplexes.