Galectin-Glycan Interactions: Guidelines for Monitoring by 77 Se NMR Spectroscopy, and Solvent (H 2 O/D 2 O) Impact on Binding

• Published in: Chemistry : a European journal Vol. 27; no. 1; pp. 316 - 325
• Main Authors: Diercks, Tammo, Medrano, Francisco J, FitzGerald, Forrest G, Beckwith, Donella, Pedersen, Martin Jaeger, Reihill, Mark, Ludwig, Anna-Kristin, Romero, Antonio, Oscarson, Stefan, Cudic, Maré, Gabius, Hans-Joachim
• Format: Journal Article
• Language: English
• Published: Germany 04.01.2021
• Subjects: Binding Sites; Deuterium Oxide; Galectins - metabolism; Humans; Isotopes; Ligands; Nuclear Magnetic Resonance, Biomolecular; Polysaccharides - metabolism; Protein Binding; Selenium; Solvents; 77Se NMR spectroscopy; calorimetry; selenoglycosides; circular dichroism; galectins
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202003143

Functional pairing between cellular glycoconjugates and tissue lectins like galectins has wide (patho)physiological significance. Their study is facilitated by nonhydrolysable derivatives of the natural O-glycans, such as S- and Se-glycosides. The latter enable extensive analyses by specific Se NMR spectroscopy, but still remain underexplored. By using the example of selenodigalactoside (SeDG) and the human galectin-1 and -3, we have evaluated diverse Se NMR detection methods and propose selective H, Se heteronuclear Hartmann-Hahn transfer for efficient use in competitive NMR screening against a selenoglycoside spy ligand. By fluorescence anisotropy, circular dichroism, and isothermal titration calorimetry (ITC), we show that the affinity and thermodynamics of SeDG binding by galectins are similar to thiodigalactoside (TDG) and N-acetyllactosamine (LacNAc), confirming that Se substitution has no major impact. ITC data in D O versus H O are similar for TDG and LacNAc binding by both galectins, but a solvent effect, indicating solvent rearrangement at the binding site, is hinted at for SeDG and clearly observed for LacNAc dimers with extended chain length.