Open AccessPeptide nucleic acids rather than RNA may have been the first genetic molecule
Author(s) -
Kevin E. Nelson,
Matthew Levy,
Stanley L. Miller
Publication year - 2000
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.97.8.3868
Subject(s) - uracil , chemistry , nucleic acid , cytosine , guanine , nucleobase , thymine , peptide nucleic acid , rna , ethylenediamine , polymerization , amino acid , glycine , nucleotide , acetic acid , biochemistry , stereochemistry , organic chemistry , dna , polymer , gene
Numerous problems exist with the current thinking of RNA as the first genetic material. No plausible prebiotic processes have yet been demonstrated to produce the nucleosides or nucleotides or for efficient two-way nonenzymatic replication. Peptide nucleic acid (PNA) is a promising precursor to RNA, consisting ofN -(2-aminoethyl)glycine (AEG) and the adenine, uracil, guanine, and cytosine-N -acetic acids. However, PNA has not yet been demonstrated to be prebiotic. We show here that AEG is produced directly in electric discharge reactions from CH4 , N2 , NH3 , and H2 O. Electric discharges also produce ethylenediamine, as do NH4 CN polymerizations. AEG is produced from the robust Strecker synthesis with ethylenediamine. The NH4 CN polymerization in the presence of glycine leads to the adenine and guanine-N 9 -acetic acids, and the cytosine and uracil-N 1 -acetic acids are produced in high yield from the reaction of cyanoacetaldehyde with hydantoic acid, rather than urea. Preliminary experiments suggest that AEG may polymerize rapidly at 100°C to give the polypeptide backbone of PNA. The ease of synthesis of the components of PNA and possibility of polymerization of AEG reinforce the possibility that PNA may have been the first genetic material.