排序方式: 共有49条查询结果,搜索用时 15 毫秒
1.
2.
3.
Vishnyakov A Widmalm G Laaksonen A 《Angewandte Chemie (International ed. in English)》2000,39(1):140-142
Molecular dynamics simulations reveal the entire solvation shell around a model disaccharide dissolved in the binary 1:3 molar mixture of dimethyl sulfoxide and water becomes distinctly structured (see drawing). Such preferential solvation is due to the large number of hydroxyl groups and the rich network of hydrogen bonds of a disaccharide formed with the solvent. 相似文献
4.
Robert Pendrill Ole W. Sørensen Göran Widmalm 《Magnetic resonance in chemistry : MRC》2014,52(3):82-86
Site‐specific 13C isotope labeling is a useful approach that allows for the measurement of homonuclear 13C,13C coupling constants. For three site‐specifically labeled oligosaccharides, it is demonstrated that using the J‐HMBC experiment for measuring heteronuclear long‐range coupling constants is problematical for the carbons adjacent to the spin label. By incorporating either a selective inversion pulse or a constant‐time element in the pulse sequence, the interference from one‐bond 13C,13C scalar couplings is suppressed, allowing the coupling constants of interest to be measured without complications. Experimental spectra are compared with spectra of a nonlabeled compound as well as with simulated spectra. The work extends the use of the J‐HMBC experiments to site‐specifically labeled molecules, thereby increasing the number of coupling constants that can be obtained from a single preparation of a molecule. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
5.
6.
Dixon AM Widmalm G Bull TE 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,147(2):266-272
One-dimensional nuclear magnetic resonance techniques were applied to the conformational investigation of a disaccharide. More specifically, nuclear Overhauser enhancements (NOEs) of protons on either side of the glycosidic bond have been used to determine the conformation of the disaccharide alpha-l-Rhap-(1 --> 2)-alpha-l-Rhap-OMe. A modified GOESY sequence, incorporating selective excitation and pulsed field gradient enhancement, was developed and used to accurately measure small NOE signals of interest. These experiments were named M-GOESY, for modified GOESY, and the data they provided were used to calculate internuclear distances in the disaccharide molecule. The accuracy of the M-GOESY measurements was enhanced by elimination of indirect effects, or spin diffusion, by selective inversion(s) of either the intermediate magnetization or the source and target magnetization during the mixing time. Results of this study indicate that the alpha-l-Rhap-(1 --> 2)-alpha-l-Rhap-OMe disaccharide molecule exists primarily in one conformation, with the glycosidic torsion angle psi approximately -30 degrees based on past molecular dynamics simulations. 相似文献
7.
8.
9.
Magnus Frnbck Lars Eriksson Gran Widmalm 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(3):o171-o173
The water content of the title compound, C13H24O10·3H2O, creates an extensive hydrogen‐bonding pattern, with all the hydroxyl groups of the disaccharide acting as hydrogen‐bond donors and acceptors. The water molecules are arranged in columns along the crystallographic b axis and form, together with one of the hydroxyl groups, infinite hydrogen‐bonded chains. The conformation of the disaccharide is described by glycosidic torsion angles of −38 and 18°. 相似文献
10.
Landström J Bergström M Hamark C Ohlson S Widmalm G 《Organic & biomolecular chemistry》2012,10(15):3019-3032
By examining the interactions between the protein hen egg-white lysozyme (HEWL) and commercially available and chemically synthesized carbohydrate ligands using a combination of weak affinity chromatography (WAC), NMR spectroscopy and molecular simulations, we report on new affinity data as well as a detailed binding model for the HEWL protein. The equilibrium dissociation constants of the ligands were obtained by WAC but also by NMR spectroscopy, which agreed well. The structures of two HEWL-disaccharide complexes in solution were deduced by NMR spectroscopy using (1)H saturation transfer difference (STD) effects and transferred (1)H,(1)H-NOESY experiments, relaxation-matrix calculations, molecular docking and molecular dynamics simulations. In solution the two disaccharides β-d-Galp-(1→4)-β-D-GlcpNAc-OMe and β-D-GlcpNAc-(1→4)-β-D-GlcpNAc-OMe bind to the B and C sites of HEWL in a syn-conformation at the glycosidic linkage between the two sugar residues. Intermolecular hydrogen bonding and CH/π-interactions form the basis of the protein-ligand complexes in a way characteristic of carbohydrate-protein interactions. Molecular dynamics simulations with explicit water molecules of both the apo-form of the protein and a ligand-protein complex showed structural change compared to a crystal structure of the protein. The flexibility of HEWL as indicated by a residue-based root-mean-square deviation analysis indicated similarities overall, with some residue specific differences, inter alia, for Arg61 that is situated prior to a flexible loop. The Arg61 flexibility was notably larger in the ligand-complexed form of HEWL. N,N'-Diacetylchitobiose has previously been observed to bind to HEWL at the B and C sites in water solution based on (1)H NMR chemical shift changes in the protein whereas the disaccharide binds at either the B and C sites or the C and D sites in different crystal complexes. The present study thus highlights that protein-ligand complexes may vary notably between the solution and solid states, underscoring the importance of targeting the pertinent binding site(s) for inhibition of protein activity and the advantages of combining different techniques in a screening process. 相似文献