Acid-Catalyzed RNA-Oligomerization from 3',5'-cGMP.

The assembly of ancient informational polymers from nucleotide precursors is the central challenge of life's origin on our planet. Among the possible solutions, dry polymerization of 3',5'-cyclic guanosine monophosphate (3',5'-cGMP) has been proposed as a candidate to create oligonucleotides of 15-20 units in length. However, the reported sensitivity of the reaction to the presence of cations raised questions of whether this chemistry could be relevant in a geological context. The experiments in this study show that the presence of cations is not restrictive as long as the reaction is conducted in an acidic environment, in contrast to previous reports that suggested optimal conditions at pH 9.

Crystallization as a selection force at the polymerization of nucleotides in a prebiotic context.

Accumulation and selection of nucleotides is one of the most challenging problems surrounding the origin of the first RNA molecules on our planet. In the current work we propose that guanosine 3',5' cyclic monophosphate could selectively crystallize upon evaporation of an acidic prebiotic pool containing various other nucleotides. The conditions of the evaporative crystallization are fully compatible with the subsequent acid catalyzed polymerization of this cyclic nucleotide reported in earlier studies and may be relevant in a broad range of possible prebiotic environments. Albeit cytidine 3',5' cyclic monophosphate has the ability to selectively accumulate under the same conditions, its crystal structure is not likely to support polymer formation.