title: Proton nuclear magnetic resonance measurement of the amide hydrogen exchange rates of group A streptococcal polysaccharide in H2O.
abstract: The solvent exchange rates of the acetamido hydrogen of the 2-acetamido-2-deoxy-beta-D-glucopyranosyl unit of group A streptococcal polysaccharide dissolved in H2O have been measured and compared with the corresponding exchange rates in the solvated model compound 1-O-methyl-2-acetamido-2-deoxy-beta-D-glucopyranoside. Amide hydrogen exchange rates were measured at 25 degrees C over a wide pH range by a combination of two separate NMR techniques: the transfer of solvent saturation and the amide hydrogen saturation recovery NMR experiments. The data indicate that the acetamido hydrogen essentially exists in a solvated environment and that its contribution to the conformational stability of this polysaccharide through intramolecular hydrogen bonding is negligible.
mesh_terms: D000577:Amides; D006859:Hydrogen; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011135:Polysaccharides, Bacterial; D013297:Streptococcus pyogenes; D014867:Water
chemical_list: D000577:Amides; D011135:Polysaccharides, Bacterial; D014867:Water; D006859:Hydrogen