Recent advances in computational predictions of NMR parameters for the structure elucidation of carbohydrates: methods and limitations.

All living systems are comprised of four fundamental classes of macromolecules--nucleic acids, proteins, lipids, and carbohydrates (glycans). Glycans play a unique role of joining three principal hierarchical levels of the living world: (1) the molecular level (pathogenic agents and vaccine recognition by the immune system, metabolic pathways involving saccharides that provide cells with energy, and energy accumulation via photosynthesis); (2) the nanoscale level (cell membrane mechanics, structural support of biomolecules, and the glycosylation of macromolecules); (3) the microscale and macroscale levels (polymeric materials, such as cellulose, starch, glycogen, and biomass). NMR spectroscopy is the most powerful research approach for getting insight into the solution structure and function of carbohydrates at all hierarchical levels, from monosaccharides to oligo- and polysaccharides.

Structure of the O-polysaccharide of Providencia alcalifaciens O8 containing (2S,4R)-2,4-dihydroxypentanoic acid, a new non-sugar component of bacterial glycans.

A glycerol teichoic acid-like O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Providencia alcalifaciens O8 and studied by chemical methods and NMR spectroscopy, including 2D ROESY, {(1)H,(13)C} HSQC, and HMQC-TOCSY experiments. It was found that the compound contains a new component of bacterial lipopolysaccharides: ether-linked (2S,4R)-2,4-dihydroxypentanoic acid (Dhpa), which was identified by NMR spectroscopy. The following structure of the repeating unit of the polysaccharide was established: [structure: see text]

New structure for the O-polysaccharide of Providencia alcalifaciens O27 and revised structure for the O-polysaccharide of Providencia stuartii O43.

The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide from Providencia alcalifaciens O27 and studied by sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including 2D (1)H,(1)H COSY, TOCSY, ROESY, H-detected (1)H,(13)C HSQC, and HMBC experiments. It was found that the polysaccharide is built up of linear partially O-acetylated tetrasaccharide repeating units and has the following structure: [structure: see text] where Qui4NFo stands for 4-formamido-4,6-dideoxyglucose (4-formamido-4-deoxyquinovose). The O-polysaccharide structure of Providencia stuartii O43 established earlier was revised with respect to the configuration of the constituent 4-amino-4,6-dideoxyhexose (from Rha4N to Qui4N).

Structure of the O-polysaccharide and serological cross-reactivity of the lipopolysaccharide of Providencia alcalifaciens O32 containing N-acetylisomuramic acid.

Unlabelled: The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Providencia alcalifaciens O32 and studied by sugar and methylation analyses, solvolysis with triflic acid, 1H and 13C NMR spectroscopy, including two-dimensional 1H,1H COSY, TOCSY, ROESY, H-detected 1H,13C HSQC and HMBC experiments. It was found that the polysaccharide has a branched tetrasaccharide repeating unit containing 2-acetamido-3-O-[(S)-1-carboxyethyl]-2-deoxy-D-glucose (D-GlcNAc3Slac, N-acetylisomuramic acid) with the following structure: [

Structure: SEE TEXT]. Serological studies with O-antisera showed antigenic relationships between P.

Structures and serology of the O-antigens of Proteus strains classified into serogroup O17 and former serogroup O35.

Introduction: Bacteria of the genus Proteus are facultative pathogens which commonly cause urinary tract infections. Based on the serological specificity of the O-chain polysaccharide of the lipopolysaccharide (O-polysaccharide, O-antigen), strains of P. mirabilis and P.