title: Molecular structure of the rhamsan-like exocellular polysaccharide RMDP17 from Sphingomonas paucimobilis.
abstract: X-Ray diffraction analysis of the sodium salt of the polysaccharide RMDP17, a 2-deoxy rhamsan analog, reveals that it adopts a gellan-like, half-staggered, threefold, left handed, double helix of pitch 57.4 A. The side chain of the branched polymer is hydrogen bonded to the main chain. Sodium ions, linked to the carboxylate groups, promote the association of helices via water molecules. Two helices of opposite polarity occupy a trigonal unit cell of dimensions a=17.6 and c=28.7 A. The packing arrangement displays a series of hydrogen bonds involving main chain and side chain atoms, as well as some water bridges, between the helices.
authors.affiliation: Whistler Center for Carbohydrate Research, 1160 Food Science Building, Purdue University, West Lafayette, IN 47907-1160, USA.
authors.forename: Wen
authors.initials: W
authors.lastname: Bian
authors.forename: Rengaswami
authors.initials: R
authors.lastname: Chandrasekaran
authors.forename: Marguerite
authors.initials: M
authors.lastname: Rinaudo
mesh_terms: D006860:Hydrogen Bonding; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D020578:Sphingomonas / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D011108:Polymers; D011135:Polysaccharides, Bacterial; C402124:RMDP17; D014867:Water; C048288:gellan gum; C071623:rhamsan