Saturation Transfer Difference in Characterization of Glycosaminoglycan-Protein Interactions.

Novel methods in nuclear magnetic resonance (NMR) spectroscopy have recently been developed to investigate the binding properties of intermolecular complexes endowed with biomedical functions. Among these methods is the saturation transfer difference (STD), which enables the mapping of specific binding motifs of functional ligands. STD can efficiently uncover the specific and preferential binding sites of these ligands in their intermolecular complexes. This is particularly useful in the case of glycosaminoglycans (GAGs), a group of sulfated polysaccharides that play pivotal roles in various biological and pathological processes. The activity of GAGs is ultimately mediated through molecular interactions with key functional proteins, namely, GAG-binding proteins (GBPs). The quality of the GAG-GBP interactions depends on sulfation patterns, oligosaccharide length, and the composing monosaccharides of GAGs. Through STD NMR, information about the atoms of the GAG ligands involved in the complexes is provided. Here we highlight the latest achievements of the literature using STD NMR on GAG oligosaccharide-GBP complexes. Interestingly, most of the GBPs studied so far by STD NMR belong to one of the three major classes: coagulation factors, growth factors, or chemokine/cytokines. Unveiling the structural requirements of GAG ligands in bindings with their protein partners is a crucial step to understand the biochemical and medical actions of GAGs. This process is also a requirement in GAG-based drug discovery and development.