Our origins-of-life research concerns molecular processes that could have contributed to the formation and persistence of nucleic-acid building blocks before biology. Ultraviolet light can drive useful transformations, but it can also destroy the same compounds. Understanding this competition requires a description of both reaction mechanisms and photostability.
In collaboration with experimental groups, we have investigated photochemical steps in routes to pyrimidine ribonucleosides and their phosphate derivatives, including photoanomerization (Xu et al., 2017). Our joint work on the selective formation of RNA pyrimidine and DNA purine nucleosides examined a chemical scenario in which precursors of both genetic polymers can coexist (Xu et al., 2020). These studies address chemically defined steps in prebiotic synthesis and their compatibility within a shared reaction network.
Related studies ask why particular precursors survive ultraviolet irradiation and how water or molecular substitution changes their reactivity. Examples include oxazoline RNA precursors (Janicki et al., 2018) and the excited-state hydrogen abstraction involved in cytidine photochemistry (Szabla et al., 2015). Our contribution is to identify molecular pathways and test their consistency with experimental observations.
Selected publications
- Xu et al. Selective prebiotic formation of RNA pyrimidine and DNA purine nucleosides. Nature 2020, 582, 60–66.
- Xu et al. A prebiotically plausible synthesis of pyrimidine β-ribonucleosides and their phosphate derivatives involving photoanomerization. Nature Chemistry 2017, 9, 303–309.
- Janicki et al. Photostability of oxazoline RNA-precursors in UV-rich prebiotic environments. Chemical Communications 2018, 54, 13407–13410.
- Szabla et al. Excited-state hydrogen atom abstraction initiates the photochemistry of β-2′-deoxycytidine. Chemical Science 2015, 6, 2035–2043.