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  • 1
    Electronic Resource
    Electronic Resource
    Theoretical studies on the conformation of saccharides. 3. Conformational properties of the glycosidic linkage in solution and their relation to the anomeric and exoanomeric effects (1980)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 102 (1980), S. 6929-6936 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00543a005
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  • 2
    Electronic Resource
    Electronic Resource
    Ab Initio Molecular Orbital Calculation of Carbohydrate Model Compounds. 3. Effect of the Electric Field on Conformations about the Glycosidic Linkage (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 6234-6241 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100016a070
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  • 3
    Electronic Resource
    Electronic Resource
    Ab initio molecular orbital calculation of carbohydrate model compounds. 2. Conformational analysis of axial and equatorial 2-methoxytetrahydropyrans (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 9477-9485 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100089a020
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  • 4
    Electronic Resource
    Electronic Resource
    Ab Initio Molecular Orbital Calculation on Carbohydrate Model Compounds. 1. The Anomeric Effect in Fluoro and Chloro Derivatives of Tetrahydropyran (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 6452-6458 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100077a006
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  • 5
    Electronic Resource
    Electronic Resource
    Theoretical studies on the conformation of saccharides (1986)
    Springer
    Theoretical chemistry accounts 70 (1986), S. 99-114 
    Details
    ISSN: 1432-2234
    Keywords: Calculation of d-glucopyranose conformations ; Solvent effect ; Anomeric ratio ; Magnitude of the anomeric effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The stereochemistry of d-glucopyranose has been studied theoretically in 11 solvents. The stability of the individual conformers in solution has been compared using a method in which the total energy is divided into the energy of an isolated molecule and the solvation energy. The structure and the energy of the isolated molecule have been estimated by geometry optimization using the PCILO quantum chemical method. The solvation energy consists of electrostatic, dispersion, and cavity terms which have been determined from calculated properties of the solute and physiochemical properties of the solvents. The influence of the solvent on rotation of the individual pendant groups and the stability of anomers have been investigated. The calculated composition of the anomeric mixture of d-glucopyranose in various solvents at 25°C (e.g., in pyridine 49% is α-anomer, in dimethyl sulfoxide 46%, and in water 32%) is in good agreement with the available experimental data and clearly demonstrates that the solvation properties of α- and β-d-glucopyranose differ. Based on the calculated abundances of anomers the magnitude of the anomeric effect has been estimated and compared with the results of corresponding calculations on other compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00532207
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  • 6
    Electronic Resource
    Electronic Resource
    Theoretical studies on the conformation of saccharides (1979)
    Springer
    Theoretical chemistry accounts 53 (1979), S. 9-19 
    Details
    ISSN: 1432-2234
    Keywords: 2-Methoxytetrahydropyran ; Saccharides, conformation of ∼ ; Pyranose ring, flexibility of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Conformations of 2-methoxytetrahydropyran as a model for the six-membered ring in aldopyranosides have been calculated by the PCILO method using the algorithm of the conjugated gradient to optimize the geometry. The calculated geometry of the fourteen basic forms of 2-methoxytetrahydropyran was found to be in agreement with the available data obtained by X-ray diffraction of pyranosides. The results indicate differences in the geometry of 2-methoxytetrahydropyran resulting from the change of the axial vs. equatorial position of the methoxyl group. These changes are particularly meaningful in the values of bond angles and they are in agreement with the anomeric and exoanomeric effects. The experimentally found differences in the energies of an axial (4 C 1) and equatorial (1 C 4) conformer, ΔG = 2.9–3.7 kJ/mol, and the dipole moment, μ = 1.20 ± 0.05 D (1D = 3.33 10−30mAs) agree well with the calculated values ΔE = 3.18 kJ/mol and 〈μ〉 = 1.18 D which, in turn, suggest that the axial conformer is preferred over the equatorial one by a ratio a:e = 78:22.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00547604
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  • 7
    Electronic Resource
    Electronic Resource
    One-bond carbon-proton coupling constants: Angular dependence in β-linked oligosaccharides (1992)
    Springer
    Journal of biomolecular NMR 2 (1992), S. 421-430 
    Details
    ISSN: 1573-5001
    Keywords: One-bond carbon-proton coupling constants ; β-Linked oligosaccharides ; Angular dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The angular dependence of1JC,H in model compounds related to β-linked oligosaccharides has been established by FPT INDO quantum chemical calculations. Values calculated for models of (1 → 1)-, (1 → 2)-, (1 → 3)- and (1 → 4)-linked disaccharides were compared, and the effect of the orientation of HO-2 elucidated. The angular dependence of1JC,H on the torsional angles ΦH and ΨH and the solvent dielectric constant (s) was characterized in the form:1JC,H = A cos2ϖ+B cosϖ + C sin2ϖ + D since + E + Fe. The1JC,H values, measured by DEPT methods for C-1-H-1 and C-X′-H-X′ in cellobiose, cyclic trisaccharide and hexopyranoses were used to adjust the calculated angular dependences. Based on the occurrence of the conformers for agarobiose, neoagarobiose, mannobiose and methyl β-xylobioside, the thermodynamically averaged 〈1JC,H 〉 values were calculated. The results obtained (〈1JC-1,H-1 〉 162.4, 〈1JC-4′, H-4′ 〉 147.6 Hz for methyl β-xylobioside; 〈1JC-1,H-1 〉 162.4 and 〈1JC-4′,H-4′] 〉 147.6 Hz for mannobiose; 〈1JC-1,H-1 〉 162.8 Hz for neo agarobiose and 〈1JC-1,H-1 〉 163.2 Hz for agarobiose) agree well with the experimental values of 162.7, 147.5, 160.4, 147.2, 160.9 and 165.7 Hz, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02192806
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  • 8
    Electronic Resource
    Electronic Resource
    Computer modelling of kappa carrageenam-mannan interactions (1994)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 7 (1994), S. 243-250 
    Details
    ISSN: 0952-3499
    Keywords: Molecular modelling ; Polysaccharide-polysaccharide interactions ; Kappa carrageenan Mannan ; Galactomannan ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Molecular modelling has been used as a theoretical approach to investigate the kappa carrageenan structure and its interaction with mannan chains. Calculations revealed the existence of six minima for the kappa carrageenan structure in solution. Two of them were very close to the structure found in the solid state. The methodology allowed the calculation of the theoretical counterpart of the structures based on x-ray fibre diffractions studies. In the second step of this study, we have shown that there is the possibility of interactions between kappa carrageenan double helices and mannan chains. This interacting process is allowed by the flexibility of the mannan chains and structural changes of the kappa carrageenan double helices. The calculations suggest that the disaccaride mannan fragment might be required for recognition. The result of our investigation are in good agreement with a model of gel structure based on experimental data. This approach could be applied to simulate and predict other associations in molecular assemblies.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300070402
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  • 9
    Electronic Resource
    Electronic Resource
    Studies on the conformational behaviour of GlcNAc-Man3-GlcNAc2 oligosaccharides using molecular dynamics simulations (1998)
    Springer
    Glycoconjugate journal 15 (1998), S. 187-191 
    Details
    ISSN: 1573-4986
    Keywords: hexasaccharides ; molecular modelling ; three-dimensional structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Three-dimensional structures of the natural substrate unit for the enzyme N-acetylglucosamine-transferase II, GlcNAc-Man3-GlcNAc2, were investigated by molecular modelling methods. Molecular dynamics (MD) and molecular mechanics calculations on two hexasaccharides, namely GlcNAc-Man3-GlcNAc2-Asn and GlcNAc-Man3-GlcNAc2-OMe were performed by the Biosym/MSI software using the CVFF and CFF95 force fields in vacuum. The MD simulations were calculated for 3 ns at different simulation temperatures and for two values of dielectric constant, = 1 and = 4. From each 3 ns trajectory, 3050 structures have been optimized. The local minima obtained have been clustered into families exhibiting similar values of glycosidic torsional angles phi, psi, and omega. The influence of the simulation conditions and force fields used on the conformational behaviour and structure of the title oligosaccharides is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006976408074
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  • 10
    Electronic Resource
    Electronic Resource
    Theoretical studies on the conformation of saccharides. V. Hydration of the acetal segment in glycosides (1983)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 23 (1983), S. 765-778 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydration sites of the acetal segment were studied in five of the most stable conformers of 2-methoxy-tetrahydropyran (MTHP) as the first step in the determination of the hydration scheme of glycosides. The intramolecular geometries of a supermolecule formed with MTHP and water were calculated by a PCILO quantum-chemical method. The hydration sites determined can be classified into two groups: (a) individual sites, in which water interacts with one oxygen only, and (b) bridging sites, in which water interacts with both oxygens. The interaction energies of the individual sites are approximately 22 kJ mol-1, and 26 and 29 kJ mol-1 in the bridging sites. An increase of the number of water molecules in the hydration shell of MTHP showed that monohydration of the glycosidic linkage oxygens was most advantageous. Despite of the fact that the hydration shell have various structures in the individual MTHP conformers, the obtained results indicate that the hydration does not operate against the anomeric or exoanomeric effects, i.e., it does not influence the equilibrium of the MTHP conformers in favor of the trans arrangements of a glycosidic bond. Therefore, the experimentally observed stabilization of the trans positions in aqueous solutions should be considered as a result of influence of water being a dielectric continuum.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560230245
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