Solution properties of the capsular polysaccharide produced by Klebsiella pneumoniae SK1

The solution properties of the capsular polysaccharide produced by Klebsiella pneumoniae SK1, SK1-CPS, were investigated by various methods. The SK1-CPS repeating unit is a branched pentasaccharide containing one glucuronic acid as single unit side chain; acetyl groups are present as non-carbohydrate substituents on the uronic acid residue in non-stoichiometric amounts. Chiro-optical, potentiometric, viscometric and rheological measurements have been performed in order to characterize the conformational behaviour of the polymer in water and in aqueous salt solutions. Under the investigated experimental conditions, changes of temperature, ionic strength and pH were shown not to induce any cooperative conformational transition. All the results obtained suggest that the solution conformation of SK1-CPS is a random coil with a certain degree of chain flexibility. The removal of the acetyl substituents apparently does not modify the overall conclusions drawn for the native polymer, except for an incipient tendency to aggregation revealed for high salt conditions.