title: Conformational studies of the capsular polysaccharide produced by Neisseria meningitidis group A.
abstract: The effect of different cations on the conformational and morphological properties of the capsular polysaccharide produced by Neisseria meningitidis group A was investigated. Circular dichroism studies showed that the presence of Na(+), NH4+ or Ca(2+) ions induced different local conformations of the polysaccharide chain through interactions with the phosphodiester group bridging the saccharide residues in the polymer chain. Atomic force microscopy experiments confirmed that the morphology of the polysaccharide chains was different depending on the nature of the counterion. Ammonium ions were associated with the presence of single polymer chains in an elongated conformation, whereas sodium ions favored the folding of the chains into a globular conformation. The addition of calcium ions produced the aggregation of a limited number of globular polysaccharide chains to form a 'toroidal-like' structure.
authors.affiliation: Department of Life Sciences, University of Trieste, Bldg C11, Via Licio Giorgieri 1, 34127 Trieste, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Foschiatti
authors.forename: Meredith
authors.initials: M
authors.lastname: Hearshaw
authors.forename: Paola
authors.initials: P
authors.lastname: Cescutti
authors.forename: Neil
authors.initials: N
authors.lastname: Ravenscroft
authors.forename: R
authors.initials: R
authors.lastname: Rizzo
mesh_terms: D016667:Bacterial Capsules / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002942:Circular Dichroism; D018625:Microscopy, Atomic Force; D038381:Neisseria meningitidis, Serogroup A / Q000737:chemistry*; D011135:Polysaccharides, Bacterial / Q000737:chemistry*
chemical_list: D011135:Polysaccharides, Bacterial