Next, as the potentially prebiotic synthesis of Ch described above does not entirely consume any of its precursors, we adopted a systems chemistry approach and investigated the ring-opening of G>P by Ch in the presence of EA, MEA, or DEA. In the event, when an aqueous solution of G>P, Ch and EA at pH 9.5 was heated at 40°C, glycerol-3-phosphoethanolamine, G3PE (0.61 ppm), and glycerol-2-phosphoethanolamine, G2PE (0.06 ppm) were detected alongside G3PC and G2PC (Fig. and). The total yield of GPCs formed in the presence of EA was higher than the total yield of GPCs generated without EA (5% vs 0.5% total yields, respectively, after ten weeks). Similar results were obtained when MEA or DEA were used in place of EA (Fig. and S7-S8). Focusing on the reaction of G>P with Ch in the presence of EA, we found that the initial rate of formation of GPCs is proportional to the concentration of EA (Fig. ). Collectively, these data suggest that the ring-opening of G>P by Ch is also general base-catalyzed, and EA, MEA, and DEA all facilitate the process. Consistent with this notion, when the reaction of G>P with Ch in the presence of EA was performed at pH 10.5, GPCs were formed in 6% cumulative yield after seven days (Fig. ). In all cases, the cumulative yields of glycerophosphoethanolamines (GPEs) and their methylated derivatives (GPMs and GPDs) were consistently higher than those of glycerophosphocholines (GPCs) (Fig. and S6-S8). Ring-opening of G>P with EA, MEA and DEA is evidently more efficient than with Ch.