9724113 Bush Biosynthetic enrichment with stable isotopes, 13C and 15N, will be employed in an NMR and molecular modeling study of the conformation and dynamics of a series of complex polysaccharides and oligosaccharides. Data on a collection of closely related structures will be analyzed to determine the influence of specific structural features, such as branching and substituent positions, on the conformation and dynamics of complex polysaccharides. The strategy of enrichment of the samples with stable isotopes will confer unique advantages to this research project, making it possible to measure accurate values of 3JCH, 3 JCC, 2JCC, and 3JHH by 3-dimensional heteronuclear NMR methods such as HMQC-NOESY, HCCH TOCSY and quantitative coherence transfer. Long range coupling constants will serve as a direct measure of the dihedral angle of the glycosidic linkage. Molecular modeling, including molecular dynamics simulation, will be used to interpret the experimental NOE and coupling constant data. Enrichment in stable isotopes will make it possible to study the conformation and dynamics of the oligosaccharides bound to lectins by using NMR spectroscopy with isotope filters. The research will provide a significant improvement in the understanding of conformation and dynamics of complex oligosaccharides and their interaction with specific binding proteins such as lectins, glycosidases and glycosyl transferases. An improved understanding of oligosaccharide conformation and dynamics will be valuable in the biotechnology of polysaccharides, which are widely used as food additives, as well as for other applications in materials science. ***
