Bengt Lindberg

Structure of the extracellular polysaccharide from xanthomonas campestris

Abstract 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.

Mass spectrometry of partially methylated alditol acetates

Abstract The mass spectra of a number of partially methylated alditol acetates, derived from methyl ethers of pentoses, hexoses, and 6-deoxyhexoses by reduction and acetylation, have been determined. Isomeric alditols having identical substitution patterns gave similar mass spectra that unambiguously determine the substitution pattern. Mass spectra should also allow determination of substitution patterns of partially methylated alditol acetates that have not previously been investigated. The method will be useful, in combination with gas-liquid chromatography, for the characterisation of different methylated sugars obtained on methylation analysis of polysaccharides.

Structural studies on the O-specific side-chains of the cell-wall lipopolysaccharide from Salmonella typhimurium 395 ms

The structure of the O-specific side-chains of the cell-wall lipopolysaccharide of Salmonella typhimurium 395 MS has been investigated. Methylation analyses of the original lipopolysaccharide, of the material obtained on mild hydrolysis of the lipopolysaccharide with acid, and of a product obtained by acetalation of all of the, free hydroxyl groups in the lipopolysaccharide, followed by alkaline deacetylation, have provided the essential information in this study. The mixtures of sugars obtained on acid hydrolysis of the different methylated products were analysed, as alditol acetates, by g.l.c.-mass spectrometry. As a result of these studies, a detailed structure of the repeating unit of these side-chains is presented.

Components of Bacterial Polysaccharides

Publisher Summary This chapter explains all the known components of bacterial polysaccharides, except the amino acids in peptidoglycans that had been reported in the literature before 1989. Five pentoses—namely, D -ribose, D - and L -arabinose, and D - and L -xylose, have been found in the hydrolyzates of bacterial polysaccharides. Six of the 18 aldohexoses,—namely, D -glucose, D - and L -mannose, D -galactose, D -allose, and L -altrose have been found in bacterial polysaccharides. Three heptoses—namely, L - glycero - D - manno -heptose, D - glycero - D - manno -heptose, and D - glycero - D - galacto -heptose have been found in bacterial polysaccharides. The aminodeoxyaldoses, when present in bacterial polysaccharides, are known as “pyranosides.” Bacterial polysaccharides may also become acidic by the substitution of sugar residues, for example, by etherification with lactic acid, acetalation with pyruvic acid, or phosphorylation; these possibilities are also discussed in the chapter. The number of known sugar components of bacterial polysaccharides at the end of 1988 was approximately 85. . The figure refers to the parent sugars, independent of the eventual substitution by O-methyl, O-(1-carboxyethyl), or other groups.

Structural studies on the specific type-14 pneumococcal polysaccharide.

The structure of the Pneumococcus type-14 capsular polysaccharide has been reinvestigated by using methylation analysis, different specific degradations, and n.m.r. spectroscopy. It is concluded that the polysaccharide is composed of tetrasaccharide repeating-units having the structure: (formula: see text).

Degradation of polysaccharides containing uronic acid residues

Abstract A method for the selective degradation of polysaccharides containing uronic acid residues is described. It involves methylation of hydroxyl and carboxyl groups, base-catalysed elimination, and mild hydrolysis with acid. The degraded product is etherified with trideuteriomethyl or ethyl groups and hydrolysed, and the resulting mixture of etherified sugars is analysed, as the alditol acetates, by g.l.c.—m.s. Comparison of this analysis with the methylation analysis of the original polysaccharide gives information on the nature of the sugar residues on either side of the uronic acid residue.

Specific Degradation of Polysaccharides

Publisher Summary This chapter discusses the chemical methods for specific or selective degradation of polysaccharides and applications of polysaccharides for structural analysis. The degradation of polysaccharides by the action of acids, followed by the fractionation and identification of the oligosaccharides formed, is one of the methods used frequently in structural polysaccharide chemistry, and it gives information both on sequences and anomeric configurations. In principle, any reaction that can be performed at the monomer level should be applicable to polysaccharides and rapid development in this field will be seen. Application of consecutive degradations, each of which should ideally be quantitative, should facilitate determination of complicated structures with moderate effort. G.l.c. an established method for the separation of the low-molecular weight products formed. Mass spectrometry and nuclear magnetic resonance spectroscopy, especially when combined with pulse Fourier transformation (PFT-n.m.r.), are becoming increasingly important for the characterization of the degradation products.

Structural studies of the Vibrio cholerae O-antigen.

The dominant part of the O-antigen of Vibrio cholerae is a homopolysaccharide composed of (1 leads to 2)-linked 4-amino-4,6-dideoxy-alpha-D-mannopyranosyl (perosaminyl) residues, in amino groups of which are acylated by 3-deoxy-L-glycero-tetronic acid. Most of the amino sugar is decomposed during acid hydrolysis. Treatment of the polymer with anhydrous hydrogen fluoride, which cleaves the glycosidic linkages but does not cause N-deacylation, followed by acid hydrolysis under mild conditions, produced the monomer in good yield. Treatment of the N-deacylated polysaccharide with nitrous acid caused deamination with concomitant rearrangements, typical of 4-amino-4-deoxyhexopyranosyl residues in which the amino group occupies an equatorial position.

Structural studies of the capsular polysaccharide from Streptococcus pneumoniae type 1.

The capsular polysaccharide from Streptococcus pneumoniae type 1 is composed of D-galactopyranosyluronic acid residues and 2-acetamido-4-amino-2,4,6-trideoxy-D-galactopyranosyl residues. The latter sugar, previously unknown in Nature, was not isolated but was identified from the products obtained on deamination of the polymer. Using n.m.r. spectroscopy, methylation analysis, and Smith degradation as the principal methods of structural investigation, it is concluded that the polysaccharide is composed of trisaccharide repeating-units having the structure: leads to 3)-alpha-Sugp-(1 leads to 4)-alpha-D-GalpA-(1 leads to 3)-alpha-D-GalpA-(1 leads to, in which Sug denotes the new sugar.