Nuclear magnetic resonance and conformational investigations of the pentasaccharide of the Forssman antigen and overlapping di-, tri-, and tetra-saccharide sequences

The ¹H and ¹³C NMR parameters, i.e., chemical shifts and coupling constants, for the pentasaccharide of the Forssman antigen and overlapping di-, tri-, and tetra-saccharide sequences thereof have been measured and assigned completely using 1D and 2D techniques, and the oligosaccharide structures have thereby been confirmed. Nuclear Overhauser effect (NOE) experiments have been carried out at three different temperatures to assess the preferred conformations of the pentasaccharide and the component oligosaccharides. The conformational preferences of the compounds mentioned above have subsequently been investigated by theoretical calculations. The flexibity and dynamics of the molecules have been studied by Metropolis Monte Carlo simulations using a modified HSEA force field, and ensemble average data have been generated and compared to data obtained experimentally.