Leveraging Glycan-Glycan Interactions to Tune the Conformation of Glycan Hairpins and Build Rigid 3D Architectures.

Glycan folding and aggregation remain poorly understood despite their essential roles in structural and biological functions. We present a reductionist approach leveraging a glycan sequence that spontaneously folds into a hairpin conformation, enabling the systematic analysis of glycan intra- and intermolecular interactions. Our modular glycan hairpin design facilitated the incorporation of various oligomers representative of naturally occurring linear polysaccharides as hairpin strands, allowing us to investigate the effects of glycan-glycan interactions (i.e., strand-strand interactions). An initial screening based on molecular dynamics simulations revealed that strand composition strongly influences conformational stability, with hairpins ranging from highly flexible to exceptionally rigid structures. Selected rigid hairpin models, based on chitin strands, were synthesized and characterized in aqueous solution by using nuclear magnetic resonance spectroscopy and small-angle X-ray scattering, providing direct experimental validation of intramolecular interactions that stabilize folding. These highly rigid secondary structures assembled into micrometer-long platelet-like architectures that were characterized with transmission electron microscopy and electron diffraction to reveal details of intermolecular interactions driving supramolecular aggregation. These findings demonstrate that hairpins are modular systems to explore molecular details of glycan-glycan interactions as well as useful building blocks to craft glycan-based architectures.