MOLECULAR-DYNAMICS SIMULATIONS OF THE N-LINKED OLIGOSACCHARIDE OF THELECTIN FROM ERYTHRINA CORALLODENDRON

Molecular dynamics simulations have been used to model the flexibility of the seven-sugar oligosaccharide of the lectin from Erythrina coral lodendron in three separate simulations: one of the isolated oligosacc haride in vacuo, one of the oligosaccharide in solution and one of the oligosaccharide linked to the protein in solution. Adiabatic conforma tional energy maps were prepared for each of the disaccharide linkages as a means of interpreting the observed dynamics and conformational a verages in terms of intramolecular energy. The inclusion of aqueous so lvent molecules appears to be necessary to reproduce the experimental conformational behavior, which also cannot be predicted well from conf ormational energy maps for the disaccharide linkages alone. The crysta llographically determined conformation does not appear to be induced b y the crystal dimerization, but is rather stable in solution, The buil d-up of fluctuations along the successive linkages of the oligosacchar ide is significant and would be sufficient to prevent branch residues from being located in most crystal structure determinations. Good gene ral agreement between the calculated solution structure and the averag e structure determined by NMR was found for most of the oligosaccharid e linkages.