To observe whether or not phosphate transfer to glycerol is catalysed by histidyl peptides we used the uncatalysed reaction for comparison. An aqueous solution of 65 mM imidazole phosphate and 1625 mM of glycerol nucleophile at pH 7.5 was dried to a paste at 22 °C (SI Section S3.8). NB: these concentrations are prebiotically relevant if we consider that in drying puddles, the concentrations can become arbitrarily high. In the paste glycerol was steadily phosphorylated and reached a yield of 20.3 ± 0.2 % over a period of 62 h (Figure , trace). Next, we performed the reaction in the presence of 65 mM His-Asp peptide. In the 31 P NMR spectra we observed the formation of the phosphorylated histidyl intermediate (Figure .62 ppm) (in situ NMR characterisation of the phosphorylated intermediate is in SI Section S2.6.1 and S5.3). Encouragingly, we observed that the formation of phosphorylated glycerol products were accelerated in the presence of His-Asp compared to the uncatalysed reaction. This is seen from the steeper increase in formation of phosphorylated glycerol over time (Figure , p trace). The yield of phosphorylated glycerol was 42.3 ± 4.9 % after 62 h -double the yield of the uncatalysed reaction.