Tetrasaccharide repeating unit

Side chain type. Sderoglycan is typical and possesses tetrasaccharide repeating units due to a 1,6-jl-D-glucosyl side-chain on every third main chain residue. 

The difficulties inherent in obtaining correct sugar analyses for a polysaccharide containing three different amino sugars are obvious. It therefore seems possible that S4 is composed of tetrasaccharide repeating-units, containing one residue each of the four different sugar components. 

The repeat distance is 18.6 A (1.86 nm), with a meridional reflection on the first layer-line. A tetrasaccharide repeating-unit was favored. It was suggested that the linkage between the 2-acetamido-2-deoxy-D-glucose and D-glucuronic acid residues is alternately a-D-(l — 4) and /3-d-(1 — 4). 

Mulloy, B., Ribeiro, A. C., Alves, A. P., Vieira, R. P., and Mourao, P. A. (2004). Sulfated fucans from echinoderms have a regular tetrasaccharide repeating unit defined by specific patterns of sulfation at the 0-2 and 0-4 positions. J. Biol. Chem. 269, 22113-22123. 

Another example of O-specific polysaccharides that are assembled through the block mechanism are the polymers from Salmonella serogroups C2 and C3. Their polysaccharide chains (18) are composed97 of linear, tetrasaccharide repeating-units having abequosyl and D-glucosyl branches,... 

Synthesis of the tetrasaccharide repeating-unit of the O-specific polysaccharide from Salmonella senftenberg. Carbohydr. Res. 5 1, 269-27 1... 

Kochetkov, N.K., Torgov, V.I., Malysheva, N.N., Shashkov, A.S., and Klimov, E.M. (1980a). Synthesis of the tetrasaccharide repeating-unit of the O-specific polysaccharide from Salmonella muenster and Salmonella minneapolis. Tetrahedron 36. 1227-1230 Kochetkov, N.K., Torgov, V.I., Malysheva, N.N., and Shashkov, A.S. (1980b). Synthesis of the pentasaccharide repeating-unit of the O-specific polysaccharide from Salmonella Strasbourg. Tetrahedron 36, 1099-1105... 

Figure 2. Block synthesis of a tetrasaccharide repeating unit of the Y O-antigen.

The substrate, i,e. the O-antigenic polysaccharide chain, can carry several substituents on the basic tetrasaccharide repeating unit in form of D-glucose residues or O-acetyl groups (Figure 7). 

Shigella flexneri LPSs comprise a large family of interrelated O-polysaccharide structures, the simplest of which belongs to the Y variant polysaccharide (Table 3). This has a tetrasaccharide repeating unit containing three L-rhamnose residues and... 

Figure 6. The tetrasaccharide repeating unit of Klebsiella K8 polysaccharide showing the atom labeling. The residue A is ft-D-glucose B is a-D-galactose C is /3-D-galactose and D is a-D-glucuronate.

OPS of Acinetobacter baumannii 024 (23) is a heteropolysaccharide that contains a 5-tV-acetyl derivative of legionaminic acid in about half of its tetrasaccharide repeating units and a S-iV-IXXi-S-hydroxybutanoyl] derivative in the remaining units35 (Fig. 6). 

In addition, to understand the polysaccharide biosynthesis of a species-specific CPS in different Campylobacter species, 6-O-methyl-D-g/ycero-a-L-g/Mco-heptopy-ranose—one of the residues of the tetrasaccharide repeating unit of the CPS of Campylobacter jejuni NCTC 11168—was synthesized [134],... 

Knowledge of the chemical repeating pattern is a prerequisite to analysis of the diffraction patterns from polysaccharides. Among the complex polysaccharides studied thus far, heparin has presented the most problems. Nieduszynski and Atkins22 -24 previously interpreted the data by using a tetrasaccharide repeat unit for heparin they have now taken the repeat unit to be a disaccharide, composed of substituted 2-amino-2-deoxy-D-glucose and L-iduronate residues.25 In a re-... 

Other variations of the tetrasaccharide repeating unit (i.e. with the rhamnosyl residue at the reducing end) are best prepared by classical approaches [64]. 

Josephson, S, Bundle, D R, Artificial carbohydrate antigens the synthesis of the tetrasaccharide repeating unit of Shigella flexneri 0-antigen, Can. J. Chem., 57, 3073-3079, 1979. 

S)mthesis of Tetrasaccharide Repeat Unit from E. coli Oil. 641... 

Inhibition of the homologous SVI rabbit anti-Pn VI system showed that large amounts (30-100 mmoles) of most sugars give up to 15% inhibition, and sugar phosphates and alditol phosphates inhibit to as much as 25%, with little relation to their presence in or absence from SVI. Kabat showed that related oligosaccharides are usually better inhibitors than monosaccharides. Thus, the phosphate-free tetrasaccharide repeating unit of SVI is a more efficient inhibitor than ribitol, ribitol 1-phosphate, or any... 

P. savastanoi strain isolated from infected oleander plants (see above), proved to be virulent on both oleander and olive plants, while olive strain was shown to be virulent only on the host plant. The molecular basis of this host-pathogen specificity is poorly understood. Exopolysaccharides (EPS) and cell-wall LPS of phytopathogenic bacteria have been correlated with pathogenesis its chemical structure and tridimensional conformation may play a role in the early infection process and in the determination of plant-bacteria interaction specificity [92]. The LPS of three strains of P. savastanoi were isolated and the structure of their O-chain portion were determined by chemical and NMR spectral analysis. For all the strains the O-chain consists of a tetrasaccharide repeating unit of three a-L-Rhap and one terminal non-reducing a-D-Fuc-p3NAc. Two rhamnosyl residues are 3-linked and the third one 2,3-linked as reported [93]. 

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