Structural investigation of the capsular polysaccharide of Klebsiella serotype K 49.

The structure of the capsular polysaccharide from Klebsiella type K 49 was investigated by 1H- and 13C-n.m.r. spectroscopy of the original, carboxyl-reduced, and Smith-degraded polysaccharides. Methylation of the original K 49 and derivatives showed that the polysaccharide consists of a tetrasaccharide repeating-unit having D-galacturonic as a single lateral substituent. All of the sugars have the alpha-D-configuration. This conclusion is in agreement with measurements of spin-lattice relaxation-times for the anomeric proton. O-Acetyl groups are located on galacturonic acid, but do not occupy a unique position. (Formula: see text).