A conformational study of α-d-Manp-(1 → 2)-α-d-Manp-(1 → O)-l-Ser by NMR 1H,1H T-ROESY experiments and molecular-dynamics simulations Original Research Article

The conformational preference of α-d-Manp-(1 → 2)-α-d-Manp-(1 → O)-l-Ser has been investigated by one-dimensional 1H,1H T-ROESY experiments and molecular-dynamics simulations with CHARMM22 type of force fields and water as explicit solvent. Proton–proton distances were obtained from the simulations and subsequently experimentally determined distances could be derived. Measurements were performed on the title compound as well as on selectively deuterium-substituted analogues synthesized as part of this study to alleviate possible NMR spectroscopic difficulties. A very good agreement was present between the separate NMR experiments. In the subsequent analysis a key nuclear Overhauser effect between the anomeric protons in the two sugar residues was used to assess the conformational dynamics revealed by the molecular simulations. The combined results support a model in which two states are significantly populated as a result of flexibility around the bond defined by the glycosidic torsion angle ψ.