UV resistance of nucleosides -- an experimental approach

TL;DR

This study investigates how nucleosides respond to UV radiation, revealing that uracil and uridine are highly sensitive while others remain stable, which has implications for prebiotic chemistry near Earth's surface.

Contribution

It provides experimental data on the UV stability of nucleosides and identifies specific photochemical reactions, such as uracil dimer formation, relevant to origin-of-life research.

Findings

Uracil and uridine are highly UV-sensitive.

Adenosine, cytidine, and guanosine are UV-stable.

Uracil forms trans-syn cyclobutane dimers under UV exposure.

Abstract

The emergence of life on Earth is a highly discussed but still unsolved question. Current research underlines the importance of environments within close proximity to the Earth's surface as they can solve long-standing problems such as polymerization of nucleotides and phosphorylation of nucleosides. However, near-surface settings, for example, ponds or ice shields, are prone to UV irradiation. We investigated the photosensitivity of uracil, uridine, adenosine, cytidine, and guanosine by using Raman microscopy. The samples were irradiated by a UV source with 150~mW/cm\textsuperscript{2} for 10 min. Uracil and uridine showed the highest photosensitivity, while adenosine, cytidine, and guanosine remained stable. The change of spectral features and ab initio quantum calculations indicate the formation of uracil's trans-syn cyclobutane dimer during UV irradiation.