Capsular Polysaccharide structure

A. Sundgren, M. Lahmann, and S. Oscarson, Block synthesis of Streptococcus pneumoniae type 14 capsular polysaccharide structures, J. Carbohydr. Chem., 24 (2005) 379-391. 

Alpe M, Oscarson S (2002) Synthesis of oligosaccharides corresponding to Streptococcus pneumoniae type 9 capsular polysaccharide structures. Carbohydr Res 337 1715—1722... 

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. 

Structure of Pneumococcus Capsular Polysaccharides, S. A. Barker and M. Stacey, Biochem. /., 82... 

Table A31 Structure 47 Rhizobium trifolii Capsular Polysaccharide ...

In some polysaccharides, the reducing terminal is linked, through a phosphoric diester linkage, to O-1 of a 2,3-di-6 -acylglycerol. This structural feature has been demonstrated for some capsular polysaccharides from E. coli and Neisseria species, - but is probably more common than that. Non-covalent linkage between the lipid part and the cell membrane may explain why extracellular polysaccharides often occur as capsules, and the high (apparent) molecular weight observed for these polysaccharides may be due to micelle formation in aqueous solution. 

There are solitary examples of other alditol phosphates as components of this class of polymers. Arabinitol 1-phosphate is part of the S. pneumoniae type 17F capsular polysaccharide. o-Glucitol 6-phosphate is a component of the group-specific polysaccharide from group B Streptococcus, which has a most unusual, ramified structure. In a polysaccharide from Nocardia... 

A structural study on lipid A and the O-specific polysaccharide of the lipopoly-saccharide from a clinical isolate of Bacteroides vulgatus from a patient with Crohn s disease was conducted by Hashimoto and coworkers [39]. They separated two potent virulence factors, capsular polysaccharide (CPS) and lipopolysaccharide (LPS), from a clinical isolate of B. vulgatus and characterized the structure of CPS. Next, they elucidated the strucmres of O-antigen polysaccharide (OPS) and lipid A in the LPS. LPS was subjected to weak acid hydrolysis to produce the lipid A fraction and polysaccharide fraction. Lipid A was isolated by PLC, and its structure was determined by MS and NMR. 

Structural studies of some 25 of the 80 different capsular polysaccharides from pneumococci have been reported. Complete structures... 

The isolation of 2,3-dimethyl-D-glucose from the hydrolysis products of certain methylated polysaccharides has been an important factor in assigning structures to these polysaccharides. From trimethyl-starch it has been recovered in about 3% yield, together with 2,3,4,6-tetra-methyl- and 2,3,6-trimethyl-D-glucopyranose, and arises from the points of linkage of the repeating chains of the amylopectin component.67,69,70 From a dimethyl-starch the yield is considerably higher (75%).71 Other sources are the methylated capsular polysaccharide of Rhizobium radici-... 

The first report of the occurrence of KDO in a structure other than LPS was that of Taylor47 on the capsular polysaccharide (K-antigen) of a clinical isolate, Escherichia coli LP1092. Almost simultaneously, Bhattachaijee and coworkers83 described an exopolysaccharide from Neisseria meningitidis serogroup 29e. This material contains KDO... 

Despite their popularity, aluminium-based adjuvants suffer from several drawbacks. They tend to effectively stimulate only the humoral arm of the immune response. They cannot be frozen or lyophylized, as either process promotes destruction of their gel-based structure. In addition, aluminium-based products display poor or no adjuvanticity when combined with some antigens (e.g. typhoid or Haemophilus influenzae type b capsular polysaccharides). 

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... 

This article, which is the fourth in the current series,1 presents a bibliographic account of the crystal structures of polysaccharides that have been published during 1977-1979. Several comprehensive reviews on the structures of glycosaminoglycans,2-5 bacterial capsular polysaccharides,3 4,6 starch,7-9 and cell-wall polysaccharides,10 and on... 

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-... 

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. 

Further examples of modified Smith degradation, in which the polyalcohol is methylated prior to hydrolysis under mild conditions, uronic acid degradation, and /3-elimination preceded by oxidation have been reported in connection with structural studies on the Klebsiella type 28 (Ref. 182), 57 (Ref. 183), 59 (Ref. 142), and 81 (Ref. 184) capsular polysaccharides. 

The disaccharide fragments listed in this Table are not found in the polysaccharides of Gram-positive cell-walls. For references on the structures of O-specific and capsular polysaccharides mentioned in this Table, see Refs. 98 and 276. b The total number of isomeric, disaccharide fragments identified in different polymers is shown in parentheses. 

The revised377 structure of the type 14 capsular polysaccharide is shown in formula 39. The precursors of the polymer were identified378 as UDP-Glc, UDP-Gal, and UDP-GlcNAc. Incorporation of a glycosyl group from... 

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