MMC and LD simulations of α-D-Manp-(1→2)-β-D-Glcp-OMe: comparison to long-range heteronuclear NMR coupling constants and to the crystal structure

Abstract

The conformational flexibility and the dynamics of α-D-Manp-(1→2)-β-D-Glcp-OMe have been investigated by Metropolis Monte Carlo (MMC) and Langevin dynamics (LD) simulations. The two simulation techniques employ different force fields, namely the HSEA force field and a CHARMm-based force field. The former shows less conformational flexibility than the latter, in which a multiple energy minima conformational space is sampled. Long-range heteronuclear nuclear magnetic resonance (NMR) coupling constants have been measured by selective excitations of the carbons at the glycosidic linkage. Calculated 3JC, H values from MMC and LD simulations show excellent agreement to those from NMR experiments. The X-ray crystal structure has a conformation within a region of the conformational space populated in both force fields.