Structural determination of the O-antigenic polysaccharide from the Shiga toxin-producing Escherichia coli O171 |
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Authors: | Ali Tara Weintraub Andrej Widmalm Göran |
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Institution: | Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Sweden. |
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Abstract: | The structure of the O-antigenic part of the lipopolysaccharide (LPS) obtained from the verotoxin-producing Escherichia coli O171 has been determined. (1)H and (13)C NMR spectroscopy techniques in combination with component analysis were used to elucidate the O-antigen structure of O-deacylated LPS. Subsequent NMR analysis of the native LPS revealed acetylation at O-7/O-9 of the sialic acid residue. The sequence of sugars was determined by inter-residue correlations in (1)H,(1)H-NOESY and (1)H,(13)C-heteronuclear multiple-bond correlation spectra. The O-antigen is composed of pentasaccharide repeating units with one equivalent of O-acetyl groups distributed over two positions: -->4)-alpha-Neu5Ac7,9Ac-(2-->6)-beta-D-Galp-(1-->6)-beta-DGlcp-->(1-->3)-beta-D-Galp-(1-->3)-beta-D-GalpNAc-(1--> Based on biosynthetic considerations, this should also be the biological repeating unit. |
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Keywords: | Escherichia coli Verotoxin Lipopolysaccharide Sialic acid NMR |
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