0-antigenic polysaccharides synthesis

Undecaprenol (bactoprenol) from Salmonella contains eleven isoprene units, and two irons and nine cis double bonds In the form of undecaprenyl phosphate, it acts as a carrier of carbohydrate residues in the biosynthesis of bacterial antigenic polysaccharides synthesis of Murein (see) also depends on undecaprenyl phosphate. In eukaryotes the Dolichol phosphates (see) function in the transfer of carbohydrate residues in the synthesis of glycoproteins and glycoli-pids. Probably the long lipid chains of these P serve to anchor them in membranes, while the phosphate group acts as a carrier by protruding into the cytoplasm. It is not known whether all P. function as carbohydrate carriers. The structural relationship between solanesol and plastoquinone-9 and ubiquinone-9, and the joint occurrence of these compounds suggest a precursor role for P. Biosynthesis of P. proceeds from mevalonic acid and the conformation of all double bonds is predetermined in early precursors. 

L.V. (1981). Synthesis of the O-antigenic polysaccharide of Salmonella newington and of its analogue differing in configuration at the only glycosidic centre. Tetrahedron 37 Suppl. 1 19-156 Lehmann, V. (1977). Isolation, purification, and properties of an... 

The architectonics of O-antigenic polysaccharides unambiguously indicates that the most appropriate approach to their synthesis is to assemble the biopolymer out of prefabricated repeating units. The practical solution of this problem can be. achieved by several pathways (cf. 7) the following three most obvious ones will be discussed. 

The synthesis of the j>. newington O-antigenic polysaccharide by the chemical polymerization pathway will be discussed as an example (J 6 J 7) The first and the most difficult task consists in the preparation of the monomer itself, i. e. , the properly functionalized, oligosaccharide repeating unit. The most usual approach is to introduce the required functions into the already-existing oligosaccharide molecule. 

Concluding this brief discussion of the pathways for synthesis of 0-antigenic polysaccharides by the... 

N. K. Kochetkov, in L. Anderson and F. M. Unger (Eds.), Synthesis of O-antigenic polysaccharides. Pathways for the polymerization of oligosaccharide repeating units, Bacterial Lipopolysaccharides Structure, Synthesis and Biological Activities, ACS Symp. Ser., Vol. 231, Amer. Chem. Soc., New York, 1983, pp. 65-81. 

B. A. Dmitriev, A. V. Nikolaev, A. S. Shashkov, and N. K. Kochetkov, Block-synthesis of higher oligosaccharides Synthesis of hexa- and nona-saccharide fragments of the O-antigenic polysaccharide of Salmonella newington, Carbohydr. Res., 100 (1982) 195-206. 

J. J. Zhang, Y. Zhu, and F. Kong, Synthesis of an L-rhamnose tetrasaccharide, the common and major structure of the repeating unit of the O-antigenic polysaccharide of a strain of Klebsiella pneumoniae and Pseudomonas hold, Carbohydr. Res., 336 (2001) 229-235. 

Construction of the o-antigenic Side Chains Polysaccharide Synthesis... 

Despite these potential advantages, the preferred source of antigenic polysaccharides for vaccine production remains isolation from bacterial culture. Isolation and chemical modification is usually a simpler process than chemical total synthesis. 

Some antigens, such as type 3 pneumococcal polysaccharide, EPS and other polymeric substances such as dextrans (poly-D-glucose) and levan (poly-D-fructose) can induce antibody synthesis without the assistance of TH cells. These are known as T-independent (Ti) antigens. Only one class of immunoglobulin (IgM) is synthesized and there is a weak memory response. 

N. K. Kochetkov, Synthesis of fragments of bacterial polysaccharides and their application for preparation of synthetic antigens, Pure Appl. Chem., 56 (1984) 923-938. 

N. K. Kochetkov, B. A. Dmitriev, and L. V. Backinowsky, New sugars from antigenic lipo-polysaccharides of bacteria Identification and synthesis of 3-0-[(R)-l-carboxyethyl]-L- rham-nose, an acidic component of Shiqella dysenteriae type 5 lipopolysaccharide, Carbohydr. Res., 51 (1976) 229-237. 

N. K. Kochetkov, B. A. Dmitriev, A. Y. Chernyak, and A. B. Levinsky, A new type of carbohydrate-containing synthetic antigen Synthesis of carbohydrate-containing polysaccharide copolymers with the specificity of 0 3 and 0 4 factors of Salmonella, Carbohydr. Res, 110 (1982) cl6-c20. 

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