Solid State Conformations and Interactions of Some Branched Microbial Polysaccharides

Abstract

The extracellular microbial polysaccharides from the E. coli K29 mutant M41, Xanthomonas campestris (Xanthan gums) and Xanthomonas phaseoli have been examined by X-ray diffraction and computer-aided molecular modeling. A detailed model has been obtained for the E. coli polysaccharide in which it has been possible to define both the molecular conformation and the crystal packing. The structure suggests possible intra- and intermolecular attractive interactions possibly involving countercations and hydrogen bonding through water molecules. Preliminary molecular conformations for the Xanthomonas polysaccharides are discussed.