Structural studies of the polysaccharide antigen of Eubacterium saburreum, Strain L 32

The structure of the polysaccharide antigen produced by Eubacterium saburreum, strain L 32, has been investigated. The principal methods used were methylation analysis, graded hydrolysis with acid, and n.m.r. spectroscopy. The polysaccharide, which contains the unusual sugar 3,6-dideoxy-D-arabino-hexose (tyvelose, Tyv), is composed of trisaccharide repeating-units having the following structure:

     

Structural studies of the polysaccharide antigen of Eubacterium saburreum, strain L. 452

The structure of the polysaccharide antigen produced by Eubacterium saburreum, strain L 452, has been investigated. Methylation analysis, graded hydrolysis with acid, and n.m.r. spectroscopy were the principal methods used. The polysaccharide is composed of trisaccharide repeating-units having the following structure:

The assignment of the β configuration to the d-ribofuranosyl residue is tentative.     

Structure of the extracellular polysaccharide from xanthomonas campestris

Xanthan gum, the extracellular polysaccharide from Xanthomonas campestris, has been reinvestigated by methylation analysis, and by uronic acid degradation followed by oxidation and elimination of the oxidized residue. The polysaccharide is composed of pentasaccharide repeating-units with the following structure:

     

Structural studies of gellan gum,an extracellular polysaccharide elaborated by Pseudomonas elodea

The structure of gellan gum, a polysaccharide of potential commercial usefulness elaborated by Pseudomonas elodea, has been investigated. It is concluded that the polysaccharide is composed of tetrasaccharide repeating-units having the following structure.

Of the repeating units, ～25% contain an O-acetyl group linked to C-6 of one of the β-d-glucopyranosyl residues.     

Structural studies on a polysaccharide from Shigella dysenteriae type 7

The polysaccharide obtained from the O-somatic antigen of Shigella dysenteriae type 7 (strain NCTC 519/66) contains d-glucose, d-galactose, and 2-acetamido-2-deoxy-d-glucose in the mole ratios of 2:1:1. From the results of methylation, periodate oxidation, graded hydrolysis, and deamination studies, the structure assigned to the repeating unit of the polysaccharide is as follows.

Oxidation studies with chromium trioxide revealed the nature of the anomeric linkages of some of the sugar residues in the polysaccharide.     

Structural studies of the Rhizobium trifolii extracellular polysaccharide

The structure of the extracellular polysaccharide of Rhizobium trifolii has been investigated. Methylation analysis, sequential degradations by oxidation and elimination of oxidized residues, uronic acid degradation, and degradation by oxidation of the acetylated polysaccharide with chromium trioxide in acetic acid were the main methods used. It is proposed that the polysaccharide is composed of heptasaccharide repeating-units having the following structure:

An unusual feature is that some of the repeating units are incomplete and lack the terminal β-d-galactopyranosyl group. The polysaccharide contains O-acetyl groups (somewhat more than 1 mol. per unit), linked to O-2 and O-3 of 4-O-substituted d-glucopyranosyl chain-residues. A previous finding that the polysaccharide contains 2-deoxy-d-arabino-hexose (2-deoxy-d-glucose) residues is erroneous.     

Structural studies of the capsular polysaccharide of Klebsiella type 37

The structure of the Klebsiella type 37 capsular polysaccharide has been investigated. Methylation analysis, various specific degradations, and n.m.r. spectroscopy were the principal methods used. It is concluded that the polysaccharide is composed of tetrasaccharide repeating-units having the structure 4-O-Lac-d-GlcA  4-O-[(S)-1-carboxyethyl]-d-glucuronic acid:

     

Structural studies of the O-antigen polysaccharide of Escherichia coli O4

The structure of the O-antigen polysaccharide of Escherichia coli O4 has been investigated using n.m.r. spectroscopy, methylation analysis, and various specific degradations. It is concluded that the O-antigen is composed of pentasaccharide repeating-units having the following structure.

This structure differs in some details from that recently proposed by Schmidt et al.     

Structural studies of the capsular antigen of haemophilus infuenzae type c

The structure of the capsular antigen from Haemophilus influenza type c has been investigated, n.m.r. spectroscopy being the principal method used. It is concluded that the antigen is composed of repeating-units having the following structure:

O-Acetyl groups are present in ～90% of the repeating-units.     

Structural investigation of the capsular polysaccharide of Escherichia coli O101 : K103 : H− using bacteriophage degradation and NMR spectroscopy

NMR spectroscopy was performed on the depyruvated capsular antigen of E. coli K103 and on the oligosaccharide obtained by depolymerisation of the native polysaccharide with a viral-borne endoglycanase. This capsular polysaccharide is the only one to be co-expressed with O group 101 and joins a small group of unusual capsular polysaccharides which possess pyruvic acid as the only acidic function. The primary structure was shown to be composed of the repeating unit:

     

The discernible,structural features of the acidic polysaccharides secreted by different Rhizobium species are the same

Octasaccharide repeating-units have been isolated from the acidic polysaccharides secreted by Rhizobium trifolii strain NA30, R. trifolii strain LPR5, R. leguminosarum strain LPR1, and R. phaseoli strain LPR49. (R. trifolii is the symbiont of clover, R. leguminosarum, of peas, and R. phaseoli, of beans). The repeating units were formed by treating the polysaccharides with an enzyme produced by a bacteriophage. The glycosyl sequence and the structures and locations of the non-glycosyl substituents were shown to be identical for repeating units derived from all of these polysaccharides, except for that derived from the polysaccharide produced by R. trifolii NA30. Therefore, the discernible structural features of the acidic polysaccharides secreted by Rhizobium species cannot be the determinant of host specificity. In support of this conclusion is the observation that R. trifolii LPR5045, produced by curing R. trifolii LPR5 of its Sym plasmid (the Sym plasmid is required for symbiosis and host specificity), secreted a polysaccharide having the same structure (including identities and locations of nonglycosyl substituents) as that of the polysaccharide secreted by its plasmid-containing parent. Thus, the structural genes that encode for synthesis of the acidic polysaccharide secreted by R. trifolii LPR5045 are not located on the Sym plasmid, and neither are the genes that encode for synthesis and attachment of non-glycosyl substituents of the polysaccharide. The possibility remains that a quantitatively minor component of the acidic polysaccharide could be a host-specific determinant.     

Antioxidative activity of polysaccharide fractions isolated from Lycium barbarum Linnaeus

Antioxidant activity of polysaccharide fractions isolated from Lycium barbarum Linnaeus was evaluated. Polysaccharides were extracted with boiling water, followed by precipitating with ethanol, protein hydrolysis, dialysis, and fractionation with a DEAE–Sepharose CL-6B column. A total of 4 fractions, including 1 neutral polysaccharide (LBPN) and 3 acidic polysaccharides were obtained, and compared with crude polysaccharide (CP), crude extract of polysaccharide (CE), deproteinated polysaccharide (DP), and deproteinated and dialyzed polysaccharide (DDP) for antioxidative activity. With the exception of CE and DDP, most polysaccharides were effective in scavenging DPPH and ABTS⁺ free radicals, superoxide anion and hydroxyl radical at 1000 μg/mL.     

Structural studies of an extracellular polysaccharide (S-198) elaborated by Alcaligenes ATCC 31853

The structure of an extracellular polysaccharide, S-198, elaborated by Alcaligenes ATCC 31853 has been investigated; methylation analysis, specific degradations, and ¹H-n.m.r. spectroscopy were the main methods used. It is suggested that the polysaccharide is composed of “repeating units” with the structure

A sugar residue in the chain may be either L-rhamnose or L-mannose and only ≈50% of the residues contain the branching α-L-rhamnopyranosyl group. The polysaccharide further contains O-acryl groups. It belongs to a group of polysaccharides, elaborated by Alcaligenes and Pseudomonas species, which all have the same linear backbone (except that some of them do not contain L-mannose) without branching or with branches that differ in their chemical structures and/or positions.     

The structure of the glycerophosphate-containing O-specific polysaccharide from <Emphasis Type="Italic">Escherichia coli</Emphasis> O130

A phosphorylated O-specific polysaccharide was obtained by mild acidic degradation of the lipopolysaccharide from the enteric bacterium Escherichia coli O130 and characterized by the methods of chemical analysis, including dephosphorylation and ¹H and ¹³C NMR spectroscopy. The polysaccharide was shown to be composed of branched tetrasaccharide repeating units containing two N-acetyl-D-galactosamine residues, D-galactose, D-glucose, and glycerophosphate residues (one of each). The polysaccharide has the following structure, which is unique among the known bacterial polysaccharides:

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Antigenic polysaccharides of bacteria: 41. Structures of the O-specific polysaccharides of <Emphasis Type="Italic">Shigella dysenteriae</Emphasis> types 4 and 5 revised by NMR spectroscopy

The earlier established structures of the acidic O-specific polysaccharides from two typical strains of the Shigella dysenteriae bacterium were revised using modern NMR spectroscopy techniques. In particular, the configurations of the glycosidic linkages of GlcNAc (S. dysenteriae type 4) and mannose (S. dysenteriae type 5) residues were corrected. In addition, the location of the sites of non-stoichiometric O-acetylation in S. dysenteriae type 4 was determined: the lateral fucose residue was shown to be occasionally O-acetylated; also, theposition of the O-acetyl group present at the stoichiometric quantity in S. dysenteriae type 5 was corrected. The revised structures of the polysaccharides studied are shown below. The known identity of the O-specific polysaccharide structures of S. dysenteriae type 5 and Escherichia coli O58 was confirmed by ¹³C NMR spectroscopy and, hence, the structure of the E. coli O58 polysaccharide should be revised in the same manner.

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where L-Rhap3Rlac2Ac is 2-O-acetyl-3-O-[(R-1-carboxyethyl]-L-rhamnose

     

Structural studies of the extracellular polysaccharides of Rhizobium japonicum strains 71A,CC708, and CB1795

Each of the serologically related, title strains produced extracellular polysaccharides that were mixtures of an acidic polysaccharide and smaller proportions of a glucan. These were separated by column chromatography and the structures of the acidic polysaccharides investigated by alkylation, specific sequential degradation, and periodate oxidation in conjunction with ¹H-n.m.r. spectroscopy. The polysaccharides from the three strains appear to be identical rhamno-4-O-methyl-glucuronans, having the following tetrasaccharide repeating-unit.

The molecular weight of the polysaccharides of strains CC708 and CB1795 was of the order of 65,000–70,000.     

Structural studies of the capsular antigen from streptococcus pneumoniae type 26

The structure of the capsular antigen from Pneumococcus type 26 has been determined by using methylation analysis, periodate-oxidation studies, and n.m.r. spectroscopy of the original and the dephosphorylated product. It is concluded that the polysaccharide is composed of repeating-units having the following structure.

The only difference between this structure and that of the type-6 antigen is that the α-l-rhamnopyranosyl residue is linked to O-4 of d-ribitol in the former, but to O-3 in the latter.     

The capsular polysaccharide of klebsiella serotype K60; a novel,structural pattern

Non-linear capsular polysaccharides of klebsiella bacteria usually have a single side-chain per repeating unit, or, less commonly, two side-chains attached to the same unit. The capsular polysaccharide from Klebsiella serotype K60 is unique in having three side-chains in the heptasaccharide repeating-unit shown. The structure, including the configuration of the glycosidic linkages, was established mainly by characterization of the oligosaccharides obtained by partial hydrolysis of both the original, capsular polysaccharide and the polymer resulting from the removal, by smith degradation, of the side chains.

     

Structural investigation of the capsular polysaccharide of Klebsiella serotype k23

Klebsiella K23 capsular polysaccharide has been investigated by the techniques of hydrolysis, methylation, Smith degradation-periodate oxidation, and base-catalysed degradation, either on the original or the carboxyl-reduced polysaccharide. The structure was found to consist of a tetrasaccharide repeating-unit, as shown below. The anomeric configurations of the sugar residues were determined by ₁H-and ¹³C-n.m.r. spectroscopy on the original and degraded polysaccharides.