Protein N-glycosylation stands out for its intrinsic and functionally related heterogeneity. Despite its biomedical interest, glycoprofile analysis remains a major scientific challenge, especially when looking for structure/function relationships within the intact glycoprotein. Herein, we present a strategy to delineate the N-glycans composition in intact glycoproteins, under physiological conditions, using solution state nuclear magnetic resonance (NMR) spectroscopy. The employed methodology allowed to dissect the glycan pattern of the IgE high affinity receptor (FcRI) expressed in human HEK 293 cells, identifying the presence and relative abundance of specific glycan epitopes.
Furthermore, the presentation and dynamics at the glycoprotein surface demonstrates that the N-glycans are essentially solvent exposed and properly presented as targets for N-glycan receptors molecules, such as lectins. In line, we also report the first NMR-based study of the interactions between an intact glycoprotein and a lectin in solution. This approach provides novel opportunities to directly detect specific glycosylation alterations as function of endo or exogenous factors and opens new avenues for the detection of specific N-glycan prognostic biomarkers and for the studies of glycan-protein interactions, accounting for the role of the glycan heterogeneity and their presentation in native glycoconjugates.