PNAs (Peptide Nucleic Acids)
PNAs are DNA analogs, in which 2-amino-ethylglycine linkages replace the normal phosphodiester bonds. In other words, they are oligonucleotide analogs containing normal DNA bases with a polyamide (protein like) uncharged backbone, where methylene carbonyl linker connects standard nucleotide bases to this backbone. This chemistry of PNAs has three important consequences :
(i) in contrast to DNA, PNAs are neutral molecules;
(ii) PNAs are achiral, avoiding the need to develop stereoselective synthesis and
(iii) artificial synthesis of PNA makes use of standard Boc or Fmoc protocols for solid-phase peptide synthesis.