Modulating Gene Function with Peptide Nucleic Acids (PNA)
Peptide nucleic acid (PNA) is a pseudo peptide DNA mimic based on an aminoethyl glycine backbone (Figure 18.1). It was introduced 15 years ago  and is in contrast to almost all other DNA analogs and mimics uncharged and achiral. Furthermore, PNA oligomers are synthesized via peptide-like solid-phase chemistry rather than DNA-like chemistry. In fact, PNA synthesis is fully and directly compatible with Boc-and Fmoc-based peptide synthesis. Obviously, PNA oligomers are not substrates for nucleases, but due to the nonnatural character of the amide (“peptide”) bond connecting individual PNA units, PNA oligomers are not susceptible to hydrolysis by peptidase or proteases either, and exhibit exquisite stability in serum and cell extracts as well as in vivo.