title: Structural determination of alginic acid and the effects of calcium binding as determined by high-field n.m.r.
abstract: The nature of the solution conformations of the alginic acid components D-mannuronan (poly-ManA) and L-guluronan (poly-GulA) from Azotobacter vinelandii were investigated by both one- and two-dimensional n.m.r. methods. Unequivocal proton assignments for both polymers as well as their constituent monomer units were made based on chemical-shift theory, coupling constant analysis, and nuclear Overhauser enhancement measurements. These data were used to investigate the interactions of poly-GulA and poly-ManA with Ca2+ ion in aqueous medium. Based on relative crosspeak integrals measured in two-dimensional phase-sensitive NOESY spectra of free and calcium-bound polymer, a model for calcium binding is proposed.
authors.affiliation: Department of Chemistry, Ohio State University, Columbus 43210.
authors.forename: C A
authors.initials: CA
authors.lastname: Steginsky
authors.forename: J M
authors.initials: JM
authors.lastname: Beale
authors.forename: H G
authors.initials: HG
authors.lastname: Floss
authors.forename: R M
authors.initials: RM
authors.lastname: Mayer
mesh_terms: D000464:Alginates / Q000737:chemistry*; D016948:Azotobacter vinelandii / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D020723:Glucuronic Acid; D006603:Hexuronic Acids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D014574:Uronic Acids / Q000737:chemistry
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D014574:Uronic Acids; C007896:guluronic acid; D020723:Glucuronic Acid; C008324:mannuronic acid; D002118:Calcium