Pneumococcus polysaccharide

Pneumococcus Group or C) Polysaccharide.—This substance, fajo -h 61° (water), is the polysaccharide constituent of the somatic part of the cell, and is common to all the pneumococcus types. It shows group specificity and is generally similar to the Type IV capsular polysaccharide. Its constituent units are probably N-acetyl-D-glucosamine, a hexose and phosphoric acid. It may be termed the carbohydrate residue of the heterophile antigen (described below) of pneumococcus which was separated by Goebel and his coworkers. 

Tj/pe IV Pneumococcus Specific Polysaccharide.— This capsular ma-terial ([alo + 33 , water) has been hydrolyzed and shown to contain units of D-glucose and N-acetyl-hexosamine. Its structure has not yet been studied. 

Capsules of pneumococci consist largely of a polysaccharide slime, but they contain in addition some protein and small amounts of other substances. The type-specificity and virulence of the pneumococci are due to their capsular polysaccharides (see Chapter VIII). The specificity of reaction for different pneumococcal types is due to variation in the capsular polysaccharide molecules. The antigenic polysaccharides are isolable from the bacteria but are more often prepared from the culture broth into which they are liberated by bacterial autolysis. Though there are more than 70 known types of pneumococci, little is known of the structures of their capsular polysaccharides save that from type III pneumococcus. This is shown to be a linear molecule of D-glucose and D-glucuronic acid units in equal amounts. They are linked alternately so that the molecule may be regarded as a chain of aldobiouronic acid units 131)  

While the compositions of other pneumococcal polysaccharides have not been fully clarified, the composition of several have been determined as follows  

Type I.D-Galacturonic acid (28%), aminosugar, and acetic acid. 

Type VIII.D-Glucose and D-glucuronic acid in 7 2 ratio. 

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Pneumococcus, polysaccharides from, 6-7 Poly(a-L-guluronic acid), 353, 355-356,415 Poly(P-D-mannuronic acid), 353-354,414 Polysaccharides, 311 -439 amino sugar derivatives, 166 chemical repeating units, 321, 324-325... 

Of great interest is the possible determination of structures of pneumococcus polysaccharides by comparison with a known chemical structure such as dextran. The extent of the cross-precipitation reactions43 of dextran with various pneumococcus antisera indicates the closeness of the relationships between the structures of dextran and of the various pneumococcus polysaccharides. 

Halohydrocarbons, as solvents for acetylation of cellulose, I, 313 Haptenes, dextrans as, II, 215 pneumococcus polysaccharide as, II, 221... 

Type I polysaccharide contains an amino sugar, acetyl residues, and is one of the few bacterial polysaccharides to contain D-galacturonic acid, (another being one described by Hassid ). All the pneumococcus polysaccharides listed by Boyd contain acetyl residues, the presence of which in the case of Type I, has a distinct influence on the serological specificity. The structural studies made on the polysaccharide reveal that it may possess a fundamental trisaccharide unit containing two molecules of a uronic acid and one of an acetylamino sugar, together with an additional acetyl residue. 

Bryan GC, Scudder J (1952) Dextran and pneumococcus polysaccharide cross-reactivity in skin tests and serum precipitin tests. Ann NY Acad Sci 55 477-478 Bygdeman S, Eliasson R (1967) Effect of dextrans on platelet adhesiveness and aggregation. Scand J Clin Lab Invest 20 17-23... 

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