| 1. |
|
|
| 2. |
|
|
| 3. |
- Larsson, Andreas, et al.
(författare)
-
Analysis of NMR J couplings in partially protected galactopyranosides*
- 2002
-
Ingår i: Organic Letters. - : American Chemical Society. - 1523-7052 .- 1523-7060. ; 4:11, s. 1831-1834
-
Tidskriftsartikel (refereegranskat)abstract
- Hydrogen bond mediated NMR J couplings offer additional structural information. The interpretation of these usually small hJ couplings are,however, not necessarily straightforward. In the present case of a carbohydrate system, a four-bond classical W coupling, 4JHO4,H5, is morereasonable on the basis of, in particular, density functional theory calculations of spin-spin coupling constants at the UB3LYP/6-311G** levelof theory.
|
|
| 4. |
- Larsson, Andreas, et al.
(författare)
-
Structural and immunochemical relationship between the O-antegenic polysaccharides from the enteroaggregative Escherichia coli strain 396/C1 and Escherichia coli O126
- 2004
-
Ingår i: Carbohydrate Research. - : Elsevier. - 0008-6215. ; 339:8, s. 1491-1496
-
Tidskriftsartikel (refereegranskat)abstract
- The structure of the O-antigen polysaccharide (PS) from the enteroaggregative Escherichia coli strain 396/C-1 has been determined. Sugar and methylation analyses together with 1H and 13C NMR spectroscopy were the main methods used. Inter-residue correlations were determined by 1H,1H-NOESY, 1H,13C-heteronuclear multiple-bond correlation and dipole–dipole cross-correlated relaxation experiments. The PS is composed of pentasaccharide repeating units with the following structure: Full-size image (2K) Analysis of NMR data reveals that on average the PS consists of 13 repeating units and indicates that the biological repeating unit contains an N-acetylglucosamine residue at its reducing end. This structure is different to that reported for the O-antigen polysaccharide from E. coli O126. Monospecific anti-E. coli O126 rabbit serum from The International Escherichia and Klebsiella Centre did not distinguish between the E. coli strain 396/C-1 and the E. coli O126 reference strain, neither in slide agglutination nor in an indirect enzyme immunoassay. Subsequent successful serotyping of the E. coli strain 396/C-1 showed it to be E. coli O126:K+:H27.
|
|
| 5. |
- Larsson, Andreas, 1975-
(författare)
-
Synthesis, structure and conformation of oligo- and polysaccharides
- 2004
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Carbohydrates are a complex group of biomolecules with a high structural diversity. Their almost omnipresent occurrence has generated a broad field of research in both biology and chemistry. This thesis focuses on three different aspects of carbohydrate chemistry, synthesis, structure elucidation and the conformational analysis of carbohydrates.The first paper describes the synthesis of a penta- and a tetrasaccharide related to the highly branched capsular polysaccharide from Streptococcus pneumoniae type 37. In the second paper, the structure of the O-antigenic repeating unit from the lipopolysaccharide of E. coli 396/C1 was determined along with indications of the structure of the biological repeating unit. In addition, its structural and immunological relationship with E. coli O126 is discussed. In the third paper, partially protected galactopyranosides were examined to clarify the origin of an intriguing 4JHO,H coupling, where a W-mediated coupling pathway was found to operate. In the fourth paper, the conformation of methyl a-cellobioside is studied with a combination of molecular dynamics simulations and NMR spectroscopy. In addition to the expected syn-conformation, detection and quantification of anti-ø and anti-ψ conformers was also possible.
|
|
| 6. |
|
|
| 7. |
- Nordmark, Eva-Lisa, 1975-
(författare)
-
Structural and Interaction Studies of Bacterial Polysaccharides by NMR Spectroscopy
- 2004
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An introduction to bacterial polysaccharides and the methods for structural determination are described in the first two parts of the thesis.In a structural elucidation of bacterial polysaccharides NMR experiments are important as is component analysis. A short description of immunochemical methods such as enzyme immunoassays is included. Two NMR techniques used for interaction studies, trNOE and STD NMR, are also discussed. The third part of the thesis discusses and summarizes the results from the included papers. The structures of the exopolysaccharides produced by two lactic acid bacteria are determined by one- and two dimensional NMR experiments. One is a heteropolysaccharide produced by Streptococcus thermophilus and the other a homopolysaccharide produced by Propionibacterium freudenreichii. The structure of an acidic polysaccharide from a marine bacterium with two serine residues in the repeating unit is also investigated. The structural and immunological relationship between two O-antigenic polysaccharides from Escherichia coli strain 180/C3 and O5 is discussed and investigated. Finally, interaction studies of an octasaccharide derived from the Salmonella enteritidis O-antigen and a bacteriophage are described which were performed with NMR experiments.
|
|
| 8. |
- Staaf, Mikael, et al.
(författare)
-
Determination of conformational flexibility of methyl α-cellobioside in solution by NMR spectroscopy and molecular simulations*
- 2004
-
Ingår i: Journal of Physical Chemistry A. - : American Chemical Society. - 1089-5639 .- 1520-5215. ; 108:18, s. 3932-3937
-
Tidskriftsartikel (refereegranskat)abstract
- The conformational flexibility of methyl α-cellobioside in water and dimethyl sulfoxide solutions was investigated by 1D 1H,1H T-ROESY experiments. In combination with molecular dynamics simulations, effective proton−proton distances could be derived using experimentally determined cross-relaxation rates. An anti-ψ-conformational state was present in both solvents confirming a previous flexibility hypothesis at this torsion angle. In water solution, an anti-φ-conformational state was also detected and quantified. These results show that already at the disaccharide level a large flexibility is present at the glycosidic linkage. In addition to the syn-conformation which is present to 93% for the title compound in water solution, the minor anti-φ- and anti-ψ-conformational states are populated to 2% and 5%, respectively.
|
|
