A glycan foldamer that uses carbohydrate–aromatic interactions to perform catalysis

In nature, the ability to catalyse reactions is primarily associated with proteins and ribozymes. Inspired by these systems, peptide-based catalysts have been designed to accelerate chemical reactions and/or ensure regio- and stereoselective transformations. We wondered whether other biomolecules (such as glycans) could be designed to perform catalytic functions, expanding the portfolio of synthetic functional oligomers. Here we report a glycan foldamer inspired by the natural Sialyl Lewis X antigen that acts as catalyst in a chemical reaction. This glycan-based catalyst benefits from structural rigidity and modular adaptability, incorporating a substrate-recognition motif alongside a catalytic active site. Leveraging the inherent ability of carbohydrates to engage in CH-π interactions with aromatic substrates, we demonstrate the recruitment and functionalization of a tryptophan via a Pictet-Spengler transformation. Our modular glycan catalyst accelerates the reaction kinetics, enabling the modification of tryptophan-containing peptides in aqueous environments. Our findings pave the way for the development of glycan-based catalysts and suggest the possibility of catalytic capabilities of glycans in biological contexts.