Etude du lipopolysaccharide de Escherichia coli K12 CR 34

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Abstract
Study of the lipopolysaccharide from Escherichia coli K12 CR34 The structure of the lipopolysaccharide from Escherichia coli K12, strain CR34 has been investigated. The lipopolysaccharide contains d‐galactose, d‐glucose, d‐glucosamine, l‐glycero‐dmannoheptose, 2‐keto‐3‐deoxyoctonate and lipid A. The core region does not contain d‐glucosamine but contains galactose, glucose, and heptose in the molar ratios 1: 3:6. Methylations were performed an the lipopolysaccharide and an the degraded polysaccharide obtained after acetic acid hydrolysis of the lipopolysaccharide. It was found that galactose is in terminal position partly in the form of galactopyranose, partly in the form of galactofuranose. A part of the heptose was found as unsubstituted heptofuranose. A mole of glucose was 1 → 2 linked and another mole of glucose was 1 → 6 linked. Periodate oxidation of the lipopolysaccharide followed by borohydride reduction eliminates galactose and only a part of glucose and of heptose. A mole of heptose gave mannose and thus it is unsubstituted in C6 and C7. One mole of glucose and one mole of heptose were not degraded by periodate oxidation. On mild acid hydrolysis of the polysaccharide a mole of glucose phosphate was identified. After Smith degradation of the lipopolysaccharide a derivative of a trisaccharide (glucose, heptose, mannose) was obtained indicating that glucose phosphate is linked to heptose in the lipopolysaccharide. On the basis of these findings the partial structure of the E. coli K12 CR34 core polysaccharide is proposed. Some chains of the core must be incomplete an account of the high amount of heptose.