Determination of the conformational flexibility of methyl α-cellobioside in solution by NMR spectroscopy and molecular simulations

The conformational flexibility of methyl alpha-cellobioside in water and dimethyl sulfoxide solutions was investigated by 1D H-1, H-1 T-ROESY experiments. In combination with molecular dynamics simulations, effective proton-proton distances could be derived using experimentally determined cross-relaxation rates. An anti-Psi-conformational state was present in both solvents confirming a previous flexibility hypothesis at this torsion angle. In water solution, an anti -Phi-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 similar to93% for the title compound in water solution, the minor anti-Phi- and anti-Psi-conformational states are populated to similar to2% and similar to5%, respectively.