Structural studies on the sialic acid polysaccharide antigen of Escherichia coli strain Bos-12

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Abstract
A polysaccharide, antigenically related to group C meningococcus, was isolated from E. coli strain Bos-12 (016;K92;NM). Like groups B and C meningococcal polysaccharide, the Bos-12 antigen is a pure polymer of sialic acid. 13C NMR studies on the meningococcal group B and C polysaccharides indicated that the former consists of sialic acid units linked 2.fwdarw.8-.alpha., but the latter contains the sialic acid residues linked 2.fwdarw.9-.alpha.. Comparison of natural abundance 13C NMR spectra of the Bos-12 polysaccharide with group B and C meningococcal polysaccharides established that Bos-12 was an equimolar mixture of 2.fwdarw.8-.alpha. linked sialic acid homopolymers or a 2.fwdarw.8-.alpha./2.fwdarw.9-.alpha. heteropolymer. The fact that Bos-12 polysaccharide precipitated with anti-group C serum but not with anti-group B serum would seem to exclude the former. Chemical studies (periodate oxidation followed by tritiated NaBH4 reduction) gave saccharides with a radioactive-labeling pattern expected for alternating 2.fwdarw.8-.alpha./2.fwdarw.9-.alpha. sialic acid linkages. Bos-12 is thus an 2.fwdarw.8-.alpha./2.fwdarw.9-.alpha. heteropolymer.