Pneumococcus, Type

In 1967, Heidelberger, Stacey et al. reported the purification, some structural features, and the chemical modification of the capsular polysaccharide from Pneumococcus Type I. Difficulties of direct hydrolysis of the polysaccharide were overcome and it was possible to identify some of the fragments in the hy-drolyzate. At least six products resulted from nitrous acid deamination. Two were disaccharides, which were identified, and sequences of linked sugar units were proposed. As modification of the polysaccharide decreased the amounts of antibody precipitated by anti-pneumococcal Type I sera, the importance of the unmodified structural features in contributing to the specificity of the polysaccharide was indicated. 

By 1945, Stacey speculated about the possibility of a structural relationship between Pneumococcus capsular polysaccharides and those produced by other organisms. With Miss Schliichterer, he had examined the capsular polysaccharide of Rhizobium radicicolum. This polysaccharide gave a precipitin reaction in high dilution, not only with Type III Pneumococcus antiserum, but also mixed with antisera from other Pneumococcus types. The chemical evidence indicated that the polysaccharide resembled the specific polysaccharides of Types I and II Pneumococcus. A decade later, the acidic capsular polysaccharide from Azoto-bacter chroococcum, a soil organism, was studied. It, too, produced serological cross-reactions with certain pneumococcal specific antisera. Although the molecular structure of the polysaccharide was not established, adequate evidence was accumulated to show a structural relationship to Type III Pneumococcus-specific polysaccharide. This was sufficiently close to account for the Type III serological cross-relationship. 

In 1947, L-rhamnose was first recognized by Stacey as a constituent of Pneumococcus Type II specific polysaccharide. This finding was confirmed, in 1952, by Kabat et al. and in 1955 again by Stacey when 2,4- and 2,5-di-O-methyl-L-rhamnose were synthesized and the former was shown to be identical with a di-O-methylrhamnose, obtained by hydrolysis of the methylated polysaccharide. This result indicated a pyranose ring structure for the rhamnose units in the polysaccharide. Announcement of the identification of D-arabinofuranose as a constituent of a polysaccharide from M. tuberculosis aroused considerable interest. The L-enantiomer had been found extensively in polysaccharides, but reports of the natural occurrence of D-arabinose had been comparatively rare. To have available reference compounds for comparison with degradation products of polysaccharides, syntheses of derivatives (particularly methyl ethers) of both d- and L-arabinose were reported in 1947. 

L-Fucosamine was found as a constituent of Pneumococcus Type V capsular polysaccharide and as a constituent of the mucopolysaccharides (glycosamino-glycans) of certain enteric bacteria A new synthesis was devised to make the amino sugar more available. 

Sugg and Hehre43 also obtained precipitin reactions with dextran or with sterile filtrates of sucrose broth cultures of L. mesenteroides (designated for convenience strain A) and not only anti-Leuconostoc sera, but also pneumococcus Types II, XII and XX antisera. Leuconostoc organisms cultured on D-glucose broth neither stimulated the production of dextran-reactive antibodies in rabbits, nor absorbed dextran-reactive antibodies from sera, as did organisms cultured on sucrose. Absorption with the homologous bacteria (Leuconostoc, pneumococcus Types II,... 

Dextran resulting from the action of another strain of L. mesenteroides (designated for convenience, strain B) was more soluble than strain A dextran and exhibited somewhat different immunological reactions. This strain B dextran reacted only slightly with pneumococcus Type XII antisera and had a narrower zone of antigenic reactivity than the strain A dextran. In addition, the strain A organisms exhibited a greater capacity to absorb antibodies reactive with the B dextran than did the B bacteria to absorb antibodies reactive with the A dextran. 

This enzymically synthesized dextran differed from that formed by L. mesenteroides organisms only in its lower relative viscosity. Both types of dextran are serologically similar (see page 215). Each reacts with antisera of Leuconostoc and of pneumococcus Types II, XX, and XII, and comparable ratios of activity against these antisera were observed. 

The separation and identification of disaccharides is often an important step in the elucidation of the structure of a natural polysaccharide, and Percival484 has published useful data on the O-trimethyl-silyl derivatives of a variety of disaccharides and their reduction products. In some instances, the trimethylsilyl ethers of the disaccharide alditols have lower retention times than those of the disaccharide derivatives. The per-O-trimethylsilyl derivatives of gentiobi-itol and maltitol were encountered in studies on the structure of Pneumococcus Type II capsular polysaccharide.4843... 

Barker and coworkers have applied gel chromatography in studies of pneumococcal polysaccharides.121 Purification of the type-specific polysaccharide of Pneumococcus Type II was effected by chromatography on Sephadex G-200 in M sodium chloride in this way, the ribonucleic acid, a persistent impurity in preparations of this polysaccharide, was almost completely removed. The complex formed between the polysaccharide and the nucleic acid is largely dissociated in M sodium chloride, so that the two are free in this solvent and may be separated on the basis of their differing molecular size. 

The work of Baddiley and collaborators256 259 on teichoic acids provides excellent examples of the use of deamination in the elucidation of oligosaccharide structure. For example, when treated with nitrous acid (see Scheme 9), the hexasaccharide 140, the repeating unit of the Pneumococcus Type XA capsular polysaccharide, gave 2-... 

The sulfone degradation has been applied to other polysaccharides, in particular to the product obtained from the Pneumococcus type 2 polysaccharide after methylation and uronic acid elimination (see Section IV,2, p. 218).127 Only about one third of the terminal D-glucose residues was eliminated, and an analysis of... 

Oxidation of the carboxyl-reduced and acetylated Pneumococcus type 2 capsular polysaccharide revealed that only one L-rhamnose residue in the hexasaccharide repeating-unit, later demonstrated to have the structure 60, was oxidized and, consequently, /3-L-linked.156 Replacement of 2,3,6-tri-O-methyl-D-glucose in the methylation analysis of the original polysaccharide by 2,3,4,6-tetra-O-methyl-D-glucose in that of the oxidized polysaccharide established that this L-rhamnose residue is linked to 0-4 of a D-glucose residue. The analysis also showed that it was an L-rhamnose residue in the chain (and not the branching L-rhamnose residue) that was /3-linked. 

Baddiley and coworkers used V-deacetylation-deamination in structural studies on two oligosaccharides containing 2-amino-2-deoxy-D-galactose that had been obtained by dephosphorylation of the capsular substances from Pneumococcus types 10A (Ref. 177) and 29 (Ref. 13), respectively. The former (110) yielded 2-O-a-D-galac-... 

E. Venkata Rao, J. G. Buchanan, and J. Baddiley, Type-specific substance from pneumococcus type 10A-— structure of the dephosphorylated repeating unit, Biochem. J. 700 801 (1966). 

A polymaltose prepared by Ricketts and Rowe140 reacted with pneumococcus Type XII antiserum more extensively than did a polyglucose prepared by the same authors, but both polysaccharides left behind some antibody reactive with glycogen. Neither polymer reacted with Type II antiserum. Polygalactose gave a slight precipitate with Type IV antiserum, the capsular polysaccharide of which is known to contain D-galactose. 

Tri-O-methyl-D-glucose-(4— 1) 2,3,4-tri-O-methyl-D-glucosiduronic acid Pneumococcus Type III specific polysaccharide B 0 64a... 

Structural Feature of Pneumococcus Type XIX Specific Polysaccharide, T. Miyazaki and J. K. N. Jones, Chem. Pharm. Bull., 17 (1969) 1531-1533. 

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