Fluorogenic Photo-Crosslinking of Glycan-Binding Protein Recognition Using a Fluorinated Azido-Coumarin Fucoside

Glycan recognition by glycan-binding proteins is central to the biology of all living organisms. The efficient capture and characterization of relatively weak non-covalent interactions remains an important challenge in various fields of research. Photoaffinity labeling strategies can create covalent bonds between interacting partners, and photoactive scaffolds such as benzophenone, diazirines and aryl azides have proved widely useful. Since their first introduction, relatively few improvements have been advanced and products of photoaffinity labeling remain difficult to detect. We report a fluorinated azido-coumarin scaffold which enables photolabeling under fast and mild activation, and which can leave a fluorescent tag on crosslinked species. Coupling this scaffold to an alpha-fucoside, we demonstrate fluorogenic photolabeling of glycan-protein interactions over a wide range of affinities. We expect this strategy to be broadly applicable to other chromophores and we envision that such fluoro-crosslinkers could become important tools for the traceable capture of non-covalent binding events. Photoaffinity labeling has been a staple of chemical biology for the capture of non-covalent interactions. Through conjugation of a trifluorinated 7-azido-coumarin to an alpha-fucoside, we demonstrate fluorogenic photo-crosslinking of glycan-protein interactions. This strategy and these fluoro-crosslinkers enable traceable photoaffinity labeling and could prove uniquely valuable for imaging biological recognition of glycans.image

Automated summary

Glycan recognition by glycan-binding proteins is crucial in biology, and photoaffinity labeling is an important method for capturing non-covalent interactions. This study presents a novel fluorinated azido-coumarin scaffold that enables fast and mild photolabeling, leaving a fluorescent tag on the crosslinked species. By coupling this scaffold to an alpha-fucoside, the researchers demonstrate fluorogenic photolabeling of glycan-protein interactions with varied affinities. This strategy and these fluoro-crosslinkers have the potential to be widely used for traceable capture of non-covalent binding events.