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For the emergence of life, the abiotic synthesis of RNA from its monomers is a central step. We found that in alkaline, drying conditions in bulk and at heated air‐water interfaces, 2′,3′‐cyclic nucleotides oligomerised without additional catalyst, forming up to 10‐mers within a day. The oligomerisation 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 oligomerised most efficiently. Quantification was performed using HPLC coupled to ESI‐TOF by fitting the isotope distribution to the mass spectra. Our study suggests a oligomerisation mechanism where cGMP aids the incorporation of the relatively unreactive nucleotides C, A and U. The 2′,3′‐cyclic ribonucleotides 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. [ABSTRACT FROM AUTHOR]

Previous studies on the polymerization of 3',5' cyclic guanosine monophosphate (cGMP) demonstrated the potential of the compound in the abiotic generation of the first oligonucleotide sequences on the early Earth. These experiments were conducted under idealized laboratory conditions, which logically raises the question whether the same chemistry could take place in the harsh environment present on our planet in its earliest days. In the current study, we focus on the mineralogical context of this chemistry and show that numerous, but not all, common minerals assumed to be present on the early Earth could host the polymerization of H‐form 3',5' cGMP. In particular, we have found that quartz varieties are especially suitable for this purpose, similar to andalusite, amphibole or micas. On the contrary, olivine, calcite, and serpentine‐group minerals interfere with the studied polymerization chemistry. Our results show that crystallization on mineral surfaces, which is mainly a diffusion controlled process, determines the ability of 3',5' cGMP to polymerize. The observation that numerous amorphous and crystalline SiO2 forms are compatible with the oligomerization chemistry suggests that the process could commonly occur in a wide range of primordial environments allowing for crystallization of the cyclic monomers from a dropping solution. [ABSTRACT FROM AUTHOR]

Polymerization of 3′,5′ cyclic guanosine monophosphate (3′,5′ cGMP) was previously reported to afford short RNA sequences from a plausible mildly activated prebiotic precursor in a non‐enzymatic and template‐free manner. In the current paper we analyze the reaction with PAGE as well as by infrared micro‐ and nanospectroscopy on time scales not considered before. We provide evidence that a preliminary oligomerization step in dry state allows for a continued synthesis of RNA oligomers even in the presence of subsequently added water. On a longer time scale, the oligomerization yield oscillates in an apparently chaotic fashion hinting at the importance of some non‐reversible phase‐separation processes on the experimentally observed outcome of the polymerization/degradation chemistries. The long‐lasting (hundreds of hours) intrinsic sustainability and resilience of the process gives a robust prebiotic potential to this unique oligomerization reaction, which could lead to the very first oligonucleotide sequences on the primordial Earth. [ABSTRACT FROM AUTHOR]

Recent studies illustrate that short oligonucleotide sequences can be easily produced from nucleotide precursors in a template-free non-enzymatic way under dehydrating conditions, i.e. using essentially dry materials. Here we report that 3’,5’ cyclic AMP may also serve as a substrate of the reaction, which proceeds under moderate conditions yet with a lower efficiency than the previously reported oligomerization of 3’,5’ cyclic GMP. Optimally the oligomerization requires (i) a temperature of 80°C, (ii) a neutral to alkaline environment and (iii) a time on the order of weeks. Differences in the yield and required reaction conditions of the oligomerizations utilizing 3’,5’ cGMP and cAMP are discussed in terms of the crystal structures of the compounds. Polymerization of 3’,5’ cyclic nucleotides, whose paramount relevance in a prebiotic chemistry context has been widely accepted for decades, supports the possibility that the origin of extant genetic materials might have followed a direct uninterrupted path since its very beginning, starting from non-elaborately pre-activated monomer compounds and simple reactions. [ABSTRACT FROM AUTHOR]