PNA is a substance that contains the same bases as those found in biological nucleic acids but whose backbone is held together by amide bonds. PNAs are currently of interest in discussions about the chemical precursors of DNA and RNA.1, 2 PNAs form double-stranded complexes that closely resemble those of DNA. Moreover, the laboratory demonstration that DNA serves as a template for PNA synthesis, and vice versa, lends support to the view that one genetic polymer could have replaced another on the prebiotic Earth.
1. Bohler, C., Nielsen, P. E., and Orgel, L. E. "Template Switching
Between PNA and RNA Oligonucleotides," Nature, 376, 578
2. Nielsen, P. E. "Peptide Nucleic Acid (PNA). From DNA Recognition to Antisense and DNA Structure," Biophysical Chemistry, 68, 103 (1997).