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Structural methods

Aspects of chemical methods used in the structural elucidation of polysaccharides and complex carbohydrates have been reviewed. In a critical examination of the use of g.l.c.-m.s. in the identification of TMS ethers of monosaccharides, a standardized method, which uses a medium resolution mass spectrometer and short chromatographic columns, has been proposed. TMS Ethers of monosaccharides have been characterized by g.l.c.-chemical ionization m.s. with ammonia as reagent gas. Molecular weights were determined, and fragment ions were produced in a quantity high enough to differentiate between stereoisomers (epimers and anomers). Disaccharides have been determined by permethylation followed by g.l.c. The method has been used in the detection of carbohydrate intolerance secondary to intestinal disaccharidase deficiency. [Pg.227]

Per-O-acetyl aldononitriles and methylated aldononitrile acetates have been separated by g.I.c. on a mixed liquid phase. Chemical ionization m.s. showed the presence of peaks at M + 1 in each instance. The retention times of a number of partially methylated alditol acetates have been recorded on a variety of stationary phases. Using a combination of silica gel chromatography and g.I.c., fifteen methyl ethers of methyl a-D-galactopyranoside have been isolated from the partial methylation products of D-galactose.  [Pg.227]

Comparison of the mass spectra of the TMS derivatives of hexuronic acids and their lactones with those of other monosaccharides has revealed specific effects of the carboxy-group on the fragmentation patterns. A detailed analysis was presented of the fragmentations of the TMS derivatives of jS-D-glucopyranuronic acid, a-o-galactofuranuronic acid, and jS-o-glucofuran-urono-6,3-lactone. [Pg.227]

Neuraminic acids have been reduced with sodium borohydride and the m.s. fragmentation patterns of the corresponding peracetylated methyl esters of 5-acylamino-3,5-dideoxy-nononic and -heptonic acids have been recorded. A set of partially O-methylated derivatives of methyl A-acetyl-A-methyl-jS-o-neuraminate methyl glycoside have been prepared as reference compounds [Pg.227]

An assessment has been made of O-n.m.r. spectroscopy as an analytical tool in carbohydrate chemistry. In terms of resolution of signals of 0- [Pg.228]

The application of enzymic methods to the structural analysis of polysaccharides has been reviewed. The second part of a review on the application of g.l.c. to carbohydrates includes details of methods of methylation, and has collected m.s. data for TMS, acetyl, trifluoroacetyl, and methyl derivatives of sugars. The high reactivity of methyl trifluoromethanesulphonate (methyl triflate) makes it a suitable reagent for methylation of carbohydrates under mild conditions. Since the high reactivity of this triflate limits the choice of solvent for the methylation, hydrophilic carbohydrates cannot normally be methylated by this procedure. [Pg.215]

Mass spectral data for the primary fragmentations of partially ethylated alditol acetates have been tabulated so as to allow easy reference in the identification of these polysaccharide derivatives. A newly developed, highly polar, capillary column gave improved separations of many ethylated alditol acetates when compared with the corresponding methylated derivatives. Results have been presented which demonstrate that the molar flame-responses of partially methylated and partially ethylated alditol acetates should be calculated on the basis of [Pg.215]

Monneret, J. C. Florent, I. Kabore, and Q. Khuong-Huu, /. Carbohydrates, Nucleosides, [Pg.216]

procedure that establishes the DP of oligo- and poly-saccharides has been developed. The oligo(poly)saccharide was reduced prior to hydrolysis and conversion of the reducing sugars liberated into their oxime derivatives the DP was determined from the ratio of acetylated aldononitrile to acetylated alditol. A similar technique, which determined the ratio of aldose acetate to alditol acetate, was used to measure the DP of amylose.  [Pg.217]

122 Yamada, M. Hisaniatsu, and M. Taki, J. Agric. Chent. Soc. Japan, 1975,49, 163. [Pg.217]

A treatise on Organic Chemistry contains a chapter on polysaccharides which includes details of all the important structural methods.  [Pg.243]

Danielsson, B. Mattiasson, R. Karlsson, and F. Winqvist, Biotechnol. Bioeng., 1979, 21, 1749. [Pg.243]

Tabata, S. Okada, and T. Murachi, Clin. Chim. Acta, 1979, 95, 411. [Pg.243]

Spectroscopy, — Structures of polysaccharides have been investigated using Fourier-transform i.r. difference spectra. The i.r. absorbance difference spectra of dextrans have been correlated to the type and degree of branching of the polysaccharide which have previously been established by permethylation analysis. [Pg.244]

spectra of seven hetero-oligosaccharides isolated from blood-group substance H have been recorded. The data obtained confirmed their structures. [Pg.244]

Polysaccharide methodology, with particular emphasis on such analytical techniques as g.l.c., m.s., and and n.m.r. spectroscopy and on fragmentation procedures, has been reviewed.  [Pg.243]

of the corresponding peracetylated aldononitriles has permitted 2,3,4- and 2,3,6-tri-O-methyl-D-glucose to be separated for the first time. Chemical-ionization mass-spectral data for most of the possible methylated hexitol acetates that can be derived from D-glucose, o-galactose, and D-mannose have been recorded. Many arrangements of the 0-methyl and 0-acetyl groups can be distinguished on the basis of the chemical-ionization mass spectra. [Pg.243]

Sierra, G. Sanchez-Pedreno, T. P. Ruiz, and C. Martinez Lozano, Analyt. Chim. Acta, 1977,94,129. [Pg.243]

Aspinall, in Carbohydrates , ed. G. O. Aspinall, MTP International Review of Science, Organic [Pg.243]

Kovadik, V. Mihalov, T, Higuchi, J. Hirsh, and P. KovaC, J. Carbohydrates, Nucleosides, Nucleotides, 1977, 4, 223. [Pg.243]

The influence of intrinsic and extrinsic Cotton effects on the o.r.d. and c.d. spectra of acetate and xanthate derivatives of polysaccharides has been studied.  [Pg.215]

Differences in the c.d. spectra of oligosaccharides containing 2-acetamido-2-deoxy-D-glucopyranosyl and 2-acetamido-2-deoxy-D-mannopyranosyl residues have been related to the presence of /S-(l 4)- and j8-(l - 2)-linkages. This [Pg.216]

The anomeric configuration of D-xylose liberated from /S-o-xylopyranosides by jS-D-xylosidase from Bacillus pumilus has been determined by an enzymic procedure, based on the stereospecificity of D-xylose isomerases. The initial hydrolysis product is a-D-xylose, indicating that this jS-D-xylosidase, unlike other glycosidases, acts by inversion of configuration. [Pg.216]

Details of a number of established chemical methods used in determining various aspects of the fine structures of polysaccharides-for example, the specific degradation of polysaccharides containing uronic acid residues by base-catalysed elimination, the location of acyl substituents, and the distribution of singleunit side-chains of D-galactose in galactomannans by alkaline hydrolysis of 6-deoxy-6-(4-tolylsulphonyl)hexopyranosides -are reported in the latest volume in the series Methods in Carbohydrate Chemistry . [Pg.216]


Many phenomena in solid-state physics can be understood by resort to energy band calculations. Conductivity trends, photoemission spectra, and optical properties can all be understood by examining the quantum states or energy bands of solids. In addition, electronic structure methods can be used to extract a wide variety of properties such as structural energies, mechanical properties and thennodynamic properties. [Pg.113]

Also, the result of any diffraction-based trial-and-error fitting is not necessarily unique it is always possible that there exists another untried structure that would give a better fit to experiment. Hence, a multi-teclmique approach that provides independent clues to the structure is very fniithil and common in surface science such clues include chemical composition, vibrational analysis and position restrictions implied by other structural methods. This can greatly restrict the number of trial structures which must be investigated. [Pg.1752]

B3.2 Quantum structural methods for the solid state and surfaces... [Pg.2201]

PAW is a recent addition to the all-electron electronic structure methods whose accuracy appears to be similar to that of the general potential LAPW approach. The implementation of the molecular dynamics fonnalism enables easy stmcture optimization in this method. [Pg.2214]

Goedecker S 1999 Linear scaling electronic structure methods Rev. Mod. Phys. 71 1085... [Pg.2232]

Page M, Doubleday C and Mclver J W Jr 1990 Following steepest descent reaction paths. The use of higher energy derivatives with ab initio electronic structure methods J. Chem. Phys. 93 5634 and references therein... [Pg.2359]

Eoresman, J. B. Erisch A., 1996. Exploring Chemistry with Electronic Structure Methods 2nd ed. Gaussian Inc. Pittsburgh, PA. [Pg.335]

J. B. Foresman, JE. Frisch, Exploring Chemutry with Electronic Structure Methods Gaussian, Pittsburgh (1996). [Pg.29]

R. A. Albright, Orbital Interactions in Chemistry John Wiley Sons, New York (1998). A. R. Leach, Molecular Modelling Principles and Applications Longman, Essex (1996). J. B. Foresman, JE. Frisch, Exploring Chemistry with Electronic Structure Methods Gaussian, Pittsburgh (1996). [Pg.105]

D. F. Feller, MSRC Ah Initio Methods Benchmark Suite—A Measurement of Hardware and Software Performance in the Area of Electronic Structure Methods WA Battelle Pacific Northwest Labs, Richland (1993). [Pg.133]

The cost of performing the hazard identification step depends on the size of the problem and the specific techniques used. Techniques such as brainstorming, what-if analyses, or checklists tend to be less expensive than other more structured methods. Hazard and operability (HAZOP) analyses and failure modes and effects analyses (FMEAs) involve many people and tend to be more expensive. But, you can have greater confidence in the exhaustiveness of HAZOP and FMEA techniques—their rigorous approach helps ensure completeness. However, no technique can guarantee that all hazards or potential accidents have been identified. Figure 8 is an example of the hazards identified in a HAZOP study. Hazard identification can require from 10% to 25% of the total effort in a QRA study. [Pg.32]

Richardson, J.S. Describing patterns of protein tertiary structure. Methods Enzymol. 115 349-358, 1985. [Pg.33]

Richardson, J.S. Schematic drawings of protein structures. Methods nzywo/. 115 359-380, 1985. [Pg.33]

Matthews, B.W., Rossmann, M.G. Comparison of protein structures. Methods Enzymol. 115 397-420, 1985. [Pg.33]

Exploring Chemistry with Electronic Structure Methods... [Pg.3]

Electronic structure methods use the laws of quantum mechanics rather than classical physics as the basis for their computations. Quantum mechanics states that the energy and other related properties of a molecule may be obtained by solving the Schrodinger equation ... [Pg.5]

For any but the smallest systems, however, exact solutions to the Schrodinger equation are not computationally practical. Electronic structure methods are characterized by their various mathematical approximations to its solution. There are two major classes of electronic structure methods ... [Pg.5]


See other pages where Structural methods is mentioned: [Pg.97]    [Pg.1753]    [Pg.2154]    [Pg.2202]    [Pg.2206]    [Pg.2212]    [Pg.2212]    [Pg.2217]    [Pg.2221]    [Pg.222]    [Pg.401]    [Pg.25]    [Pg.182]    [Pg.8]    [Pg.167]    [Pg.178]    [Pg.131]    [Pg.134]    [Pg.41]    [Pg.86]    [Pg.5]   
See also in sourсe #XX -- [ Pg.345 ]

See also in sourсe #XX -- [ Pg.76 ]




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A Methods for Investigating Crystallographic Structure

A Testing Ground for Electronic Structure Methods

AIMD simulation method electronic structure calculations

Alkaloid structures spectral methods, study

Analytical methods techniques, molecular structural

Application of Monte Carlo Methods to Structure Simulation

Application of Structure-based Alignment Methods for 3D QSAR Analyses

Atomic electronic structure methods

Band-structure method

Basic Descent Structure of Local Methods

Basic electronic structure methods

Bayesian Methods for Structural Dynamics and Civil Engineering Ka-Veng Yuen

Born-Oppenheimer approximation electronic structure methods

Carlo Quantum Methods for Electronic Structure

Checklist of Methods for Finding Transition Structures

Colloidal methods catalysts structure

Computational methods electronic structure calculations

Computational methods structural kinetic modeling

Computational methods, liquid structure

Computer-aided structure elucidation methods

Configuration-interaction methods electronic structure calculations

Constraint methods, tertiary protein structure

Copolymers structure-based method

Crazing Incidence X-ray Methods for Near-surface Structural Studies

Crystal structure Rietveld method

Crystal structure calculation cluster method

Crystal structure prediction Monte Carlo methods

Crystal structure prediction search method

Crystal structures determination methods

Crystal structures direct methods

Crystalline structure characterization methods

Crystallographic structure refinement methods

Data mining methods, component structure

Deconvolution method, structural

Deconvolution method, structural refinement

Density functional theory electronic structure methods

Descent structure of local methods

Determination of 4-Connected Framework Crystal Structures by Simulated Annealing Method

Diffraction methods absolute structure determination

Diffraction methods structure reliability

Direct methods of structure solution

Direct methods structure invariants

Discrete variational methods electronic structures

Docking methods structure-based

Drug design protein structure-based methods

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Electron structure methods

Electronic structure CNDO method

Electronic structure Green-function methods

Electronic structure Hartree-Fock, restricted, method

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Electronic structure computations methods

Electronic structure computations wavefunction-based methods

Electronic structure configuration-interaction methods

Electronic structure full-potential methods

Electronic structure methods

Electronic structure methods B3LYP functional

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Electronic structure methods ONIOM

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Electronic structure methods adiabatic approximation

Electronic structure methods approximation

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Electronic structure methods exchange-correlation functional

Electronic structure methods for excited states

Electronic structure methods frozen core

Electronic structure methods independent-particle models

Electronic structure methods linear scaling

Electronic structure methods local density approximation

Electronic structure methods parameterization

Electronic structure methods periodic density functional theory

Electronic structure methods periodic systems

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Electronic structure methods variational problem

Electronic structure moments methods

Electronic structure real-space methods

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Electronic structure variational methods

Electrospinning method structures

Empirical methods of solving crystal structures

Enzymatic methods, determining oligosaccharide structures

Exchange integrals electronic structure methods

Excited Structure Analyzed by Equilibrium Method

Experimental Structural Methods

Exploring Chemistry with Electronic Structure Methods

Fedors Method Atomic and Structural Contributions

Films structure electron diffraction methods

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First-principles Methods for Predicting Protein Structure

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Gradient-based Methods for Determination of Cluster Structures at Zero Temperature

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Homopolymers structure-based method

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Impact of Spectroscopic Methods on Structure Elucidation

Incorrect structures resulting from inappropriate use of purification or analytical methods

Information about crystal structures from other methods

Ionization methods, mass structures

Kekule Structures Counting Method

Light polarized, structural analysis methods using

Linear Recursive Methods - Kekule Structure Counting

MOLECULAR STRUCTURES BY COMPUTATIONAL METHODS

Mass Spectrometric Methods for Complete Structure

Method development for structural studies

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Molecular Structures of Phosphazenes Determined by -Ray Diffraction Methods

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Molybdate method structure

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Powder Structure Characterization by Gas Adsorption and Other Experimental Methods

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Prediction of Open-framework Aluminophosphate Structures by using the AASBU Method with Lowensteins Constraints

Preparative Methods and Structure

Protein secondary structure, methods

Protein secondary structure, methods study

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Starch Structure, Properties and Physical Methods of Analysis

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Structural bulk analysis of heavy crude oil fractions n-d-M method

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Structure Constants and the LMTO Method

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Structure Prediction from Sequence by Statistical Methods

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Structure refinement the Rietveld method

Structure simulation models using methods

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Structure-based Cheminformatics Approach to Virtual Screening The CoLiBRI Method

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Structure/property estimation method

Structured environment methods

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Structures, different methods

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Velocity structure inversion method

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