0-antigenic polysaccharides

D-Glucose is the most common sugar in Nature, and has always been found as the a- or >ff-pyranoside. The finding of -D-glucofuranosyl residues in the 0-antigen polysaccharide from" Erwinia amylovora T was therefore unexpected, and should be confirmed. 

In preparation for use as a surrogate vaccine, these peptides were synthesized as conjugates to tetanus toxoid, and in this form also competed with the 0-antigen polysaccharide for binding [104]. Whether these peptides will function as effective immunogenic mimics will likely depend on their propensity to adopt the bioactive conformation in solution. A certain amount... 

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

The first step in bacteriophage infection is the adsorption of the phage to a receptor on the bacterium. Almost every structure on the surface of a bacterial cell, or extending from it, can act as (or include) phage receptors (29). The 0-antigenic polysaccharide chains of the LPS are no exgeption in this respect. Since it has been estimated that 10 > to 10 LPS molecules are found on each bacterial cell (30), it is evident that part of the... 

This is not as surprising as one may be tempted to believe since with the exception of the nature of the dideoxyhexose residue the 0-antigenic polysaccharide chains are identical (Figure 1). 

Norberg, A. Lindberg and S.B. Svenson, The conformation of salmonella 0-antigenic polysaccharide chains of serogroups A, B and D1 predicted by semi-empirical, hard sphere (HSEA) calculations. Carbohydr. Res., 130 (1984), 23. 

Kim and co-workers synthesized the repeat unit of the 0-antigen polysaccharide from Danish Helicobacter pylori strains, 431 (O Scheme 69) [214]. Coupling of donor CB L-rhamno-side 427 and acceptor BCB D-rhamnoside 428 gave a-disaccharide 429a in 88% yield. Selective hydrogenolysis of latent BCB disaccharide afforded active CB disaccharide 429b in... 

LPS is located in the outer membrane of Gram-negative bacteria and composed of 0-antigen polysaccharide, core polysaccharide, and lipid A. It was found that lipid A is the key compo-... 

The Salmonella are examples of such pathogens. There are hundreds of Salmonella species and strains that produce immunologically distinct 0-antigen polysaccharides. This apparent complexity, results from relatively small variations of a single basic structure. 

Figure 6.19. Structures of 3,6-dideoxy sugars found in 0-antigen polysaccharides.

The mechanism for the polymerization of the teichoic acids has not been definitively established, but it is most probably very similar to the biosyntheses of the other lipid-coenzyme-dependent polysaccharides, the peptidomurein and Salmonella 0-antigen polysaccharide, in which the monomer unit or repeating unit attached to the lipid polyprenol pyrophosphate carrier is inserted between the growing chain and the lipid coenzyme carrier. See Fig. 10.12B for the proposed mechanism for teichoic acid biosynthesis. 

V. Salmonella O-antigen synthase elongates the 0-antigen polysaccharide by transferring a tetrasaccharide from bactoprenol pyrophosphate tetrasaccharide... 

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