A Peptide Nucleic Acid Embedding a Pseudopeptide Nuclear Localization Sequence in the Backbone Behaves as a Peptide Mimic

In this paper, the synthesis of a short modified peptide nucleic acid (PNA), obtained by using several different L-amino acids as synthons, is shown. The synthesis was performed by a submonomeric strategy, obtaining a model trimeric PNA containing embedded amino acid derived side chains in its backbone that mimic the peptide sequence PKKKRKV, which is a nuclear localization signal (NLS) widely used for translocating cargo molecules into cell nuclei. Fluorescence experiments demonstrated that this modified PNA, and not a standard unmodified PNA having the same nucleobase sequence, was able to penetrate Rhabdomyosarcoma cellnuclei, exactly behaving as the NLS standard peptide.