Fig. 4: Enhanced compositional diversity in the amino acid-catalysed co-oligomerisation of A/U and G/C/A/U nucleoside 2′,3′-cyclic phosphates.

a Concentrations of the A/U-oligomers of different lengths and compositions are plotted in the absence (grey circles) and presence (blue circles) of valine on a log scale. The blue trace represents random oligomerisation in which A and U are equally efficient. b Average relative yield (ratio of the RNA yield in the presence and absence of valine) is presented for 2−5 mer RNA with differential G incorporation in G/C/A/U copolymerisation. The average is calculated considering all compositions in the set (for example: HH includes AA, AU, AC, CC, CU and UU). c−e The RNA oligomers (3−5 mer) are expanded for various compositions, in which the concentrations (top) of the oligomers in the absence (grey) and presence (blue) of valine are presented. The blue trace represents random oligomerisation, where all nucleotides are assumed to have equal efficiency. The distribution ratio of the oligomers is adjusted based on the total yield of the n-mers in the performed reaction. The bottom plot shows the relative yield (fold increase) for each sequence composition. In the experiments, 40 mM cyclic nucleotides and 100 mM valine at pH 10 and 50 µl were rapidly dried and incubated for 20 h at 25 °C. The quantifications were done by LC-MS and a self-written LabVIEW programme. The results are the mean with S.D. of three independent experiments, and we show the largest S.D. in each data set (complete errors in Figs. S25a and S31). The isotopic distribution AAAAA and GGGCC is identical, and both concentrations are assumed equal, marked by ^∗ in (e). All isotope fits are given in Supplementary Data 3. Source data are available for all panels (a−e).