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The importance of multivalency for N‐glycan‐protein interactions has primarily been studied by attachment of minimal epitopes to artificial multivalent scaffold and not in the context of multi‐antennary glycans. N‐glycans can be modified by bisecting GlcNAc, core xylosides and fucosides, and extended N‐acetyl lactosamine moieties. The impact of such modifications on glycan recognition are also not well understood. We describe here a chemoenzymatic methodology that can provide N‐glycans expressed by the parasitic worm S. mansoni having unique epitopes at each antenna and containing core xyloside. NMR, computational and electron microscopy were employed to investigate recognition of the glycans by the human lectin DC‐SIGN. It revealed that core xyloside does not influence terminal epitope recognition. The multi‐antennary glycans bound with higher affinity to DC‐SIGN compared to mono‐valent counterparts, which was attributed to proximity‐induced effective concentration. The multi‐antennary glycans cross‐linked DC‐SIGN into a dense network, which likely is relevant for antigen uptake and intracellular routing. [ABSTRACT FROM AUTHOR]

The glycan structures of the receptor binding domain of the SARS‐CoV2 spike glycoprotein expressed in human HEK293F cells have been studied by using NMR. The different possible interacting epitopes have been deeply analysed and characterized, providing evidence of the presence of glycan structures not found in previous MS‐based analyses. The interaction of the RBD 13C‐labelled glycans with different human lectins, which are expressed in different organs and tissues that may be affected during the infection process, has also been evaluated by NMR. In particular, 15N‐labelled galectins (galectins‐3, ‐7 and ‐8 N‐terminal), Siglecs (Siglec‐8, Siglec‐10), and C‐type lectins (DC‐SIGN, MGL) have been employed. Complementary experiments from the glycoprotein perspective or from the lectin's point of view have permitted to disentangle the specific interacting epitopes in each case. Based on these findings, 3D models of the interacting complexes have been proposed. [ABSTRACT FROM AUTHOR]