For the emergence of life, the abiotic synthesis of RNA from its monomers is a central step. We found alkaline, uncatalysed drying conditions in bulk and at heated air-water interfaces where 2´,3´-cyclic nucleotides polymerised, forming up to 10-mers within a day. The polymerisation proceeded at a pH range of 7-12 at temperatures between 40-80 °C and was marginally enhanced by K+ ions. Among the canonical ribonucleotides, cGMP polymerised most efficiently. Quantification was performed using HPLC coupled to ESI-TOF by fitting the isotope distribution to the mass spectra. Our study suggests a polymerisation mechanism where cGMP aids the incorporation of the relatively unreactive nucleotides C, A and U. The 2´,3´-cyclic nucleotides are byproducts of prebiotic phosphorylation, nucleotide syntheses and RNA hydrolysis, indicating direct recycling pathways. The simple reaction condition offers a plausible entry point for RNA to the evolution of life on early Earth.
The title was revised to be more specific about the importance of the results. Figures were improved to reflect more details of the results. The introduction, results and the discussion sections were further elaborated. Some recent and relevant references are added. New figures are added to the SI.
RNA polymerisation without catalyst from 2’,3’-cyclic nucleotides by drying at air water interfaces