Unprecedented Affinity Labeling of Carbohydrate-Binding Proteins with s‑Triazinyl Glycosides

Carbohydrate–protein interactions trigger a wide range of biological signaling pathways, the mainstays of physiological and pathological processes. However, there are an incredible number of carbohydrate-binding proteins (CBPs) that remain to be identified and characterized. This study reports for the first time the covalent labeling of CBPs by triazinyl glycosides, a new and promising class of affinity-based glycoprobes. Mono- and bis-clickable triazinyl glycosides were efficiently synthesized from unprotected oligosaccharides (chitinpentaose and 2′-fucosyl-lactose) in a single step. These molecules allow the specific covalent labeling of chitin-oligosaccharide-binding proteins (wheat germ agglutinin WGA and Bc ChiA1 D202A, an inactivated chitinase) and fucosyl-binding lectin (UEA-I), respectively.