77Se-Enriched Selenoglycoside Enables Significant Enhancement in NMR Spectroscopic Monitoring of Glycan–Protein Interactions

Abstract

Detailed investigation of ligand–protein interactions is essential for better understanding of biological processes at the molecular level. Among these binding interactions, the recognition of glycans by lectins is of particular importance in several diseases, such as cancer; therefore, inhibition of glycan-lectin/galectin interactions represents a promising perspective towards developing therapeutics controlling cancer development. The recent introduction of 77Se NMR spectroscopy for monitoring the binding of a selenoglycoside to galectins prompted interest to optimize the sensitivity by increasing the 77Se content from the natural 7.63% abundance to 99%. Here, we report a convenient synthesis of 77Se-enriched selenodigalactoside (SeDG), which is a potent ligand of the medically relevant human galectin-3 protein, and proof of the expected sensitivity gain in 2D 1H, 77Se correlation NMR experiments. Our work opens perspectives for adding isotopically enriched selenoglycans for rapid monitoring of lectin-binding of selenated as well as non-selenated ligands and for ligand screening in competition experiments.

Glycan Shape, Motions, and Interactions Explored by NMR Spectroscopy

“…A selective heteronuclear 1 H↔ 77 Se Hartmann–Hahn transfer (HeHaHa) NMR experiment was developed to this end and used in interaction studies of a selenodigalactoside and human lectins. Furthermore, 77 Se-enrichment (99%) can be obtained from elemental selenium and used for chemical synthesis of 77 Se-containing oligosaccharides . Isotopic labeling of either glycan or protein or both enables detailed investigations of carbohydrate–protein interactions as exemplified by the above and will for antibodies, which contain N-glycans linked to the Fc portion of the molecule, and glycoproteins in general be of great importance by facilitating studies that can progress our understanding of biomolecular processes.…”

Saturation Transfer Difference NMR and Molecular Docking Interaction Study of Aralkyl-Thiodigalactosides as Potential Inhibitors of the Human-Galectin-3 Protein

“…We have also synthesized several sulfur-and selenium-containing carbohydrate derivatives and tested their inhibitory potencies against hGal-3 [15,16]. Detailed structural investigation of the binding of some selenoglycosides to hGal-3 has been recently performed by NMR spectroscopy, including improved 77 Se NMR-based methods, X-ray crystallography and molecular dynamics (MD) simulations [17][18][19].…”

Exploring multivalent carbohydrate–protein interactions by NMR

“…Indirect 77 Se detection has proved to be useful to characterize the binding of galectins to various disaccharides through 2D 1 H, 77 Se CPMG-HSQMBC experiments. 55–57 Illyés et al have synthesized thio and selenogalactosides presenting clusters bearing four galactose epitopes and showed their efficacy targeting the bacterial lectin PA-IL from Pseudomonas aeruginosa . 58 Although in this approach the binding was characterized through common 1 H-STD-NMR experiments, the presence of selenium in glycomimetics is a promising alternative to analyse protein–carbohydrate interactions.…”