Determination of the Conformational Flexibility of Methyl α-Cellobioside in Solution by NMR Spectroscopy and Molecular Simulations

The conformational flexibility of methyl α-cellobioside in water and dimethyl sulfoxide solutions was investigated by 1D 1 H, 1 H T-ROESY experiments. In combination with molecular dynamics simulations, effective proton−proton distances could be derived using experimentally determined cross-relaxation rates. An anti-ψ-conformational state was present in both solvents confirming a previous flexibility hypothesis at this torsion angle. In water solution, an anti-φ-conformational state was also detected and quantified. These results show that already at the disaccharide level a large flexibility is present at the glycosidic linkage. In addition to the syn-conformation which is present to ∼93% for the title compound in water solution, the minor anti-φ- and anti-ψ-conformational states are populated to ∼2% and ∼5%, respectively.