Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Citrobacter freundii [ICD11:
XN0M3 
];
infection due to Salmonella typhi [ICD11:
XN4AM ]
NCBI PubMed ID: 8061223Publication DOI: 10.1016/0301-4622(94)00002-6Journal NLM ID: 0403171Publisher: Palo Alto, CA: Annual Reviews
Institutions: Laboratory of Developmental and Molecular Immunity, National Institute of Child Health and Development, National Institutes of Health, Bethesda, MD 20892
The capsular polysaccharide of Salmonella typhi and Citrobacter freundii (Vi) is a linear homopolymer of (1→4)-linked 2-acetamido-2-deoxy-α-D-galactopyranosyluronic acid partially O-acetylated at the C-3 position. The physico-chemical properties of the carboxyl groups of the Vi polysaccharide, as a function of different degrees of O-acetylation, were studied by potentiometric titration, circular dichroism, and their reaction with the bulky nucleophile 2-nitro-phenylhydrazine (NPH). Potentiometric titrations with K+ and Ca2+ hydroxides showed that the difference in the free energy of binding between the two cations (∆ GKCa) was inversely proportional to the degree of O-acetylation. Similar cationic effects were found when measuring circular dichroism. Moreover there was also an inverse relation between the degree of O-acetylation and the extent of binding of NPH to the carboxyl groups. These data all indicate that O-acetyl groups hinder the association of carboxyls with cations and nucleophilic reagents. This provides a possible explanation for the importance of the O-acetyl and the relative unimportance of the carboxyl groups in contributing to the immunologic properties of the Vi.
Structure type: polymer chemical repeating unit
Compound class: CPS
NCBI Taxonomy refs (TaxIDs): 546,
90370Reference(s) to other database(s): GTC:G80919ER, GlycomeDB:
4303
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There is only one chemically distinct structure:
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