The O9 Antigen of Escherichia coli

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Abstract
The lipopolysaccharide from E. coli O9:K30- was isolated in .apprx. 2% yield with aqueous 45% phenol at 65.degree. C, followed by ultracentrifugation. The polysaccharide moiety was obtained by graded hydrolysis and gel permeation chromatography. It consisted of a mannan which carried on its reducing end the core oligosaccharide of the R1 type. The mannan contained 1 .fwdarw. 2 and 1 .fwdarw. 3 linkages in a ratio of 3:2, as determined by methylation analysis and mass spectrometry. On periodate oxidation, 58% of the mannose residues were destroyed. Degradation of oligosaccharide mixtures with .alpha.-mannosidase from jack bean meal, and a specific rotation of .**GRAPHIC**. = +89.degree. indicated that all mannosyl linkages have the .alpha.-configuration. Smith degradation resulted in the liberation of mannosyl (1 .fwdarw. 3)-mannose (bound to glyceraldehyde), as established by methylation analysis. The O9 polysaccharide of E. coli apparently has a pentasaccharide repeating unit of .alpha.-mannosyl (1 .fwdarw. 3)-.alpha.-mannosyl-(1 .fwdarw. 2)-.alpha.-mannosyl-(1 .fwdarw. 2)-.alpha.-mannosyl-(1 .fwdarw. 2)-mannose, which are joined in the polysaccharide through .alpha.-(1 .fwdarw. 3)-mannosyl linkages.