Structure elucidation of the O-antigenic polysaccharide from the enteroaggregative Escherichia coli strain 62D1

Structural investigation of a novel heteropolysaccharide from the fruiting bodies of Boletus edulis

A novel water-soluble heteropolysaccharide, BEPF1, was isolated from the fruiting bodies of Boletus edulis with boiling water extraction and purified by Sephacryl S-300, with a molecular weight of 1.08×10(4)Da. Sugar composition of BEPF1 showed that it was composed of l-fucose, d-mannose, d-glucose and d-galactose in the ratio of 0.21:0.23:1.17:1.00. Methylation analysis together with (1)H, (13)C and 2D NMR spectroscopy established that BEPF1 was consisted of α-d-(1→6)-galactopyranan backbone with a terminal of α-l-fucosyl unit on O-2 of the 2-d-(2→6)-galactosyl units, β-d-(1→6)-4-O-Me-glucopyranan and β-d-(1→6)-glucopyranan backbone with a terminal β-d-glucosyl unit and it also contained a minor of 2,6-β-d-Mannopyranan residues.

Structural elucidation of a 3-O-methyl-d-galactose-containing neutral polysaccharide from the fruiting bodies of Phellinus igniarius

PIP60-1, a novel heteropolysaccharide isolated from fruiting bodies of the medicinal fungus, Phellinus igniarius, has a molecular weight of 1.71 x 10(4)Da and is composed of L-fucose, D-glucose, D-mannose, D-galactose and 3-O-Me-D-galactose in a ratio of 1:1:1:2:1. A structural investigation of PIP60-1 carried out using sugar and methylation analyses, combined with (1)H and (13)C NMR spectroscopy, including COSY, TOCSY, NOESY, HSQC and HMBC experiments, established the repeating unit of the polysaccharide as the following: [structure: see text]

The structures ofEscherichia coliO-polysaccharide antigens

Escherichia coli is usually a non-pathogenic member of the human colonic flora. However, certain strains have acquired virulence factors and may cause a variety of infections in humans and in animals. There are three clinical syndromes caused by E. coli: (i) sepsis/meningitis; (ii) urinary tract infection and (iii) diarrhoea. Furthermore the E. coli causing diarrhoea is divided into different 'pathotypes' depending on the type of disease, i.e. (i) enterotoxigenic; (ii) enteropathogenic; (iii) enteroinvasive; (iv) enterohaemorrhagic; (v) enteroaggregative and (vi) diffusely adherent. The serotyping of E. coli based on the somatic (O), flagellar (H) and capsular polysaccharide antigens (K) is used in epidemiology. The different antigens may be unique for a particular serogroup or antigenic determinants may be shared, resulting in cross-reactions with other serogroups of E. coli or even with other members of the family Enterobacteriacea. To establish the uniqueness of a particular serogroup or to identify the presence of common epitopes, a database of the structures of O-antigenic polysaccharides has been created. The E. coli database (ECODAB) contains structures, nuclear magnetic resonance chemical shifts and to some extent cross-reactivity relationships. All fields are searchable. A ranking is produced based on similarity, which facilitates rapid identification of strains that are difficult to serotype (if known) based on classical agglutinating methods. In addition, results pertinent to the biosynthesis of the repeating units of O-antigens are discussed. The ECODAB is accessible to the scientific community at http://www.casper.organ.su.se/ECODAB/.

Structural elucidation of the O-antigenic polysaccharides from Escherichia coli O21 and the enteroaggregative Escherichia coli strain 105

The structure of the O-antigen polysaccharide of the lipopolysaccharide from an enteroaggregative Escherichia coli (strain 105) has been elucidated, using primarily one-dimensional and two-dimensional NMR experiments. The sequence of residues was deduced with heteronuclear multiple-bond correlation and NOESY experiments. The structure of the repeating unit of the polysaccharide from the enteroaggregative E. coli is as follows:[sequence: see text] The structure of the O-antigen from enteroaggregative E. coli strain 105 was shown to be identical with that of E. coli O21 by sugar and methylation analyses as well as by 1H-NMR and 13C-NMR spectroscopy.