title: Effect of calcium ions on the organization of iota-carrageenan helices: an X-ray investigation.
abstract: X-ray fiber diffraction analysis confirms that calcium iota-carrageenan forms a threefold, right-handed, half-staggered, parallel, double helix of pitch 26.42 A stabilized by interchain hydrogen bonds. According to the detailed structural results, three helices are packed in a trigonal unit cell (a=23.61 and c=13.21 A). Strong interactions between the sulfate groups of neighboring helices, mediated by calcium ions and water molecules, are responsible for stabilizing the three-dimensional structure.
authors.affiliation: Whistler Center for Carbohydrate Research, Food Science Building, Purdue University, West Lafayette, IN 47907-1160, USA.
authors.forename: Srinivas
authors.initials: S
authors.lastname: Janaswamy
authors.forename: Rengaswami
authors.initials: R
authors.lastname: Chandrasekaran
mesh_terms: D002118:Calcium / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002351:Carrageenan / Q000737:chemistry*; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D002351:Carrageenan; D002118:Calcium