RNA polymerisation without catalyst from 2’,3’-cyclic nucleotides by drying at air-water interfaces

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.