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The lipopolysaccharide from Escherichia coli O9: K30 was isolated in about 2% yield with aqueous 45% phenol at 65 C, followed by ultracentrifugation. The polysaccharide moiety was obtained by graded hydrolysis and gel permeation chromatography. It consisted of a mannan which carried oil its reducing end the core oligosaccharide of the R1 type. The mannan contained 1 → 2 and 1 → 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 α‐mannosidase from jack bean meal, as well as a specific rotation of α 25 D =+ 89° indicated that all mannosyl linkages have the α‐configuration. Smith degradation resulted in the liberation of mannosyl(1 → 3)‐mannose (bound to glyceraldehyde), as established by methylation analysis. From these results we conclude that the O9 polysaccharide of E. coli has a pentasaccharide repeating unit of α‐mannosyl(1 → 3)‐α‐mannosyl‐(1 → 2)‐α‐mannosyl‐(1 → 2)‐α‐mannosyl‐(1 → 2)‐mannose, which are joined in the polysaccharide through α‐(1 → 3)‐mannosyl linkages.
Prehm et al. (Sun,) studied this question.