Structural Studies on the Glucose‐Heptose Region of the Proteus mirabilis R Core

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Abstract
Methylation analysis of the core oligosaccharide of the P. mirabilis mutant R4 (derived from serotype 028) was carried out to obtain information on the internal (glucose-heptose) region of the P. mirabilis R core. The isolated core oligosaccharide was composed of glucose, L-glycero-D-manno-heptose, 3-deoxy-D-manno-octulosonic acid (dOclA) and phosphorus in a molar ratio of about 1:2:1:1.4. It was methylated either directly or after dephosphorylation. To localize the position of the phosphate substituents, the permethylated product was dephosphorylated with HF and the oligosaccharide obtained was remethylated using C2H3I. Location of phosphate at C-7 of the terminal heptose was shown by isolation of the sugar phosphate from partial hydrolysates and GLC/mass spectrometry of the permethylated product. Combining the data of the methylation analysis with the data of NMR study allows the structure of the core oligosaccharide to be formulated.