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Structural studies of the O-antigenic polysaccharides from the enteroaggregative Escherichia coli strain 94/D4 and the international type strain Escherichia coli O82
Stockholm University, Faculty of Science, Department of Organic Chemistry.
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2009 (English)In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 344, no 18, 2528-2532 p.Article in journal (Refereed) Published
Abstract [en]

The structure of the O-antigen polysaccharides (PS) from the enteroaggregative Escherichia coli strain 94/D4 and the international type strain E. coli O82 have been determined. Component analysis and 1H, 13C, and 31P NMR spectroscopy experiments were employed to elucidate the structure. Inter-residue correlations were determined by 1H, 13C-heteronuclear multiple-bond correlation, and 1H, 1H-NOESY experiments. d-GroA as a substituent is linked via its O-2 in a phosphodiester-linkage to O-6 of the α-d-Glcp residue. The PS is composed of tetrasaccharide repeating units with the following structure:


Cross-peaks of low intensity from an α-d-Glcp residue were present in the NMR spectra and spectral analysis indicates that they originate from the terminal residue of the polysaccharide. Consequently, the biological repeating unit has a 3-substituted N-acetyl-d-glucosamine residue at its reducing end. Enzyme immunoassay using specific anti-E. coli O82 rabbit sera showed identical reactivity to the LPS of the two strains, in agreement with the structural analysis of their O-antigen polysaccharides.

Place, publisher, year, edition, pages
2009. Vol. 344, no 18, 2528-2532 p.
Keyword [en]
Escherichia coli, Lipopolysaccharide, NMR, Biological repeating unit, Glyceric acid
National Category
Organic Chemistry
URN: urn:nbn:se:su:diva-31498DOI: 10.1016/j.carres.2009.09.033ISI: 000272860500014OAI: diva2:277413
Available from: 2009-11-18 Created: 2009-11-18 Last updated: 2011-04-19Bibliographically approved
In thesis
1. Computer-Assisted Carbohydrate Structural Studies and Drug Discovery
Open this publication in new window or tab >>Computer-Assisted Carbohydrate Structural Studies and Drug Discovery
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Carbohydrates are abundant in nature and have functions ranging from energy storage to acting as structural components. Analysis of carbohydrate structures is important and can be used for, for instance, clinical diagnosis of diseases as well as in bacterial studies. The complexity of glycans makes it difficult to determine their structures. NMR spectroscopy is an advanced method that can be used to examine carbohydrates at the atomic level, but full assignments of the signals require much work. Reliable automation of this process would be of great help. Herein studies of Escherichia coli O-antigen polysaccharides are presented, both a structure determination by NMR and also research on glycosyltransferases which assemble the polysaccharides. The computer program CASPER has been improved to assist in carbohydrate studies and in the long run make it possible to automatically determine structures based only on NMR data.

Detailed computer studies of glycans can shed light on their interactions with proteins and help find inhibitors to prevent unwanted binding. The WaaG glycosyltransferase is important for the formation of E. coli lipopolysaccharides. Molecular docking analyses of structures confirmed to bind this enzyme have provided information on how inhibitors could be composed. Noroviruses cause gastroenteritis, such as the winter vomiting disease, after binding human histo-blood group antigens. In one of the projects, fragment-based docking, followed by molecular dynamics simulations and binding free energy calculations, was used to find competitive binders to the P domain of the capsid of the norovirus VA387. These novel structures have high affinity and are a very good starting point for developing drugs against noroviruses. The protein targets in these two projects are carbohydrate binding, but the techniques are general and can be applied to other research projects.

Place, publisher, year, edition, pages
Stockholm: Department of Organic Chemistry, Stockholm University, 2011. 78 p.
Carbohydrates, molecular docking, molecular dynamics simulation, fragment-based virtual screening, NMR spectroscopy, computer-aided drug design, computer-aided structure elucidation, glycosyltransferases, Escherichia coli
National Category
Organic Chemistry
Research subject
Organic Chemistry
urn:nbn:se:su:diva-56411 (URN)978-91-7447-245-5 (ISBN)
Public defence
2011-05-25, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Manuscript. Paper 6. Manuscript.Available from: 2011-05-03 Created: 2011-04-15 Last updated: 2012-07-03Bibliographically approved

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Lundborg, MagnusWidmalm, Göran
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