Selection of Ribofuranose-Isomer Among Pentoses by Phosphorylation with Diamidophosphate

The unique structure-function relationship of the ribofuranose ring in RNA has inspired various chemical pathways to select for the ribofuranose form (over the ribopyranose form), especially in a prebiotic context. Herein we show that the reaction of diamidophosphate (DAP) with the four pentoses-ribose, arabinose, xylose, and lyxose-naturally selects the ribofuranose form more efficiently when compared to the other three pentoses. All four pentoses form the initial diamidophosphate-adduct; however, ribose undergoes rapid conversion to ribofuranose-1,2- and 2,3-cyclicphosphate products, while the other three pentoses show significant accumulation of the initially formed DAP-adducts and slow conversion to the cyclicphosphate products. Arabinose and xylose show a distribution between furanose- and pyranose-1,2-cyclicphosphate products, while lyxose forms the furanose-1,2- and pyranose-2,3-cyclicphosphate products. This trend is also manifested when starting from a mixture of pentoses where ribofuranose 1,2-amidocyclicphosphate dominates the product distribution. Such selection for ribofuranose among pentoses by phosphorylation i) provides another venue of how a ribofuranose structure can selectively emerge through abiotic chemical reaction suitable for elaboration toward RNA and ii) adds to the body of experimental work addressing the chemical origin of RNA.