Structure of the capsular K3 antigen of Escherichia coli 04:K3:H4, a polysaccharide containing a 4-deoxy-2-hexulosonic acid.
The K3-antigenic capsular polysaccharide (K3 antigen) of Escherichia coli contains L-rhamnose, a 4-deoxy-2-hexulosonic acid, and an O-acetyl group in the molar ratio of 3:1:1. The backbone consists of a ----2)-O-alpha-L-rhamnopyranosyl-(1----3)-O-alpha-L-rhamnopyranosyl-(1----3)-O-alpha-L-rhamnopyranosyl-(1---- repeating unit. Either one of the 3-linked L-rhamnopyranosyl residues of each repeating unit may be substituted at O-2 with a 4-deoxy-2-hexulosonic acid, an isomer of the furanosyl form of KDO, about 90% of which is acetylated at 0-6. The 4-deoxy-2-hexulosonic acid residue is linked to the L-rhamnan backbone in a very labile linkage which is split by 1% acetic acid (30 min, 100 degrees). The K3 polysaccharide has a molecular weight of approximately 38,000, corresponding to approximately 60 repeating units.
Dengler
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Max-Planck-Institut f:ur Immunbiologie, D-7800 Freiburg (Federal Republic of Germany).
Himmelspach
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Jann
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Jann
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D000942:Antigens, Bacterial / Q000032:analysis*; D002240:Carbohydrate Sequence; D004926:Escherichia coli / Q000276:immunology*; D008969:Molecular Sequence Data; D013400:Sugar Acids / Q000032:analysis*
C061734:4-deoxy-2-hexulosonic acid; D000942:Antigens, Bacterial; D013400:Sugar Acids