Pseudaminic acid

Table I) and CPSs of Sinorhizobium.13,14 Recently, pseudaminic acid or its enantiomer has been reported as a component of surface bacterial glycoproteins pilin of P. aeruginosa15 and flagellins of Campylobacter jejuni and Campylobacter coli 6... 

OPSs of P. aeruginosa 09 (6, 7) include the same pseudaminic acid derivative but with the (i )-3-hydroxybutyryl group at N-522 (Fig. 2). 

Single O-linked residues of pseudaminic acid derivatives (or its enantiomer) modify flagellin, the major structural protein of the... 

Fig. 3. Structures of OPSs of Pseudomonas aeruginosa 07 (8-10)23 and the serine-linked trisaccharide chain of pilin of P. aeruginosa 1244 (ll).15 (Pse, pseudaminic acid FucNAc, 2-ace tamido-2,6-dideoxygalactose.)...

Structures of pseudaminic acid-containing OPSs from other bacteria (12-16) are shown in Fig. 4. OPSs of Vibrio cholerae 0 225 (13) and Escherichia coli 013626 (14) show marked structural similarities. 

Fig. 4. Structures of OPSs containing pseudaminic acid (Pse). (QuiNAc, 2-acetamido-2,6-dideoxyglucose.)...

A role of the 5-A-acyl group of pseudaminic acid in serospecificity was demonstrated in studies of P. aeruginosa serogroup 07 strains, which could be divided into three subgroups 07a,7b,7c, 07a,7b,7d, and 07a,7d (Section II.2, Fig. 3). It was concluded that epitopes 07c and 07d are linked to the 5-TV-[(R)-3-hydroxybutanoyl] and 5-A-acetyl group, respectively.23... 

Glycosylation of the proteins has the potential to influence the interaction of the cell with its environment. The presence of negatively charged pseudaminic acid derivatives on the surface would lower the isoelectric point, influence solubility, and likely increase ionic interactions.15 In C. jejuni flagellin, these may be further controlled by introduction of a basic acetamidino group to the sugar.16... 

When the monosaccharide was not available directly after hydrolysis or solvolysis of the polysaccharide, a monomeric derivative for MS analysis could be obtained by a combination of chemical modifications and cleavages. Thus, in order to obtain an open-chain derivative of pseudaminic acid, OPS of S. boydii type 7 (Fig. 4, structure 12) was carboxyl-reduced, hydrolyzed under mild acid conditions, the products were carbonyl-reduced, solvolyzed with anhydrous hydrogen fluoride, and methylated.9,24... 

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