A conformational study of alpha-L-Rhap-(1----2)-alpha-L-Rhap-(1----OMe) by NMR nuclear Overhauser effect spectroscopy (NOESY) and molecular dynamics calculations.

The conformational preference of the disaccharide alpha-L-Rhap-(1----2)-alpha-L-Rhap-(1----OMe) (1) about the glycosidic torsion angles, phi and psi, was studied by NMR NOESY spectroscopy and molecular mechanics calculations. The NOE data were consistent with either of two distinct conformations close to minima on a calculated phi/psi potential energy surface. Starting from the lowest energy conformation, a 1-ns molecular dynamics (MD) trajectory was computed in vacuo, from which the NOE curves were simulated and compared to the experimentally observed NOESY data.