2-Alkyl Furans Undergo Radiolytic Oxidative Protein Cross-Linking.

Induced covalent bond formation, or cross-linking, is a powerful strategy for interrogating and modulating biological systems. Current strategies rely largely on photochemical processes, which generally restrict their use to cellular or other optically accessible settings. Broadening the chemistry underlying the cross-linking-initiating event could extend these approaches to more complex biological systems. Ionizing radiation─a cornerstone of cancer therapy─is an attractive but unexplored trigger for covalent chemistry. Here, we detail the systematic comparison of a series of rationally designed radiolytic cross-linking candidates. These studies reveal that 2-alkyl furans efficiently label a representative protein in a radiation dose-dependent manner. Mechanistic analyses suggest that radiolysis induces hydroxyl radical-mediated oxidation of the furan, generating an electrophilic dicarbonyl intermediate that reacts with lysine residues to form stable adducts. We apply this strategy to enforce the covalent capture of an otherwise reversible small-molecule-protein interaction in cells. Together, these findings establish ionizing radiation as an effective trigger for covalent chemistry, expanding the scope of radiolytic chemistry to include bond formation. This work provides a foundation for future applications leveraging spatially targeted radiation for target identification or the development of next-generation therapeutic strategies.