High-resolution NMR

High-resolution applications of NMR in food science have been reviewed.26 Since the appearance of this review in 1984, the use of 2D NMR techniques has become commonplace, greatly increasing the power of NMR as a method for structural analysis of complex natural products, including many minor food components. In this section, however, attention will be given to quantitative rather than structural applications of high-resolution NMR. 

From the above information it appears that high spin iron(III) is not an ideal metal ion to be studied by high resolution NMR because of the dramatic effects on linewidths. In small complexes, xr may be the correlation time especially if it is considered that r may increase with the external magnetic field [14]. 

NMR studies of porphyrin-containing iron(III) complexes are very many owing to their importance in biological systems. The porphyrin systems are tetradentate dianionic ligands and essentially planar, as reported in Fig. 5.7, and allows easy access of monodentate ligands to both the axial coordination positions [15]. 

The occupancy of the d orbitals in high spin porphyrin compounds is of the type shown in Fig. 5.1 under the heading D4h. Such occupancy accounts for both 

The H NMR spectra of ferricytochromes d are typical of high spin iron(III). The iron atom is pentacoordinated, with four ligands provided by the nitrogen atoms of a porphyrin (see Fig. 5.7) and the fifth ligand being a histidine residue exposed to the solvent. Being a cytochrome of c type, the heme moiety is covalently bound to two cysteinyl residues by means of thioether links (Fig. 5.11). 

The shifts of the nuclei of the heme axial ligand, which often is an imidazole 

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Figure Bl.l 1.2 represents the essential components of a modem high-resolution NMR spectrometer, suitable for studies of dissolved samples. The magnet has a superconducting coil in a bath of liquid Fie, jacketed by...

Kowalewski J and Maler L 1997 Measurements of relaxation rates for low natural abundance /=1/2 nuclei Methods for Structure Elucidation by High-Resolution NMR ed Gy Batta, K E Kdver and Cs... 

Figure 7.11 Methylene proton portion of the 220-MHz NMR spectrum of poly(methyl methacrylate) (a) predominately syndiotactic and (b) predominately isotactic. [From F. A. Bovey, High Resolution NMR of Macro molecules, Academic, New York, 1972, used with permission.]...

Bovey, F. A., High Resolution NMR of Macromolecules, Academic, New York, 1972. 

R. Komoroski, ed.. High Resolution NMR Spectroscopy of Synthetic Polymers in Bulk, VCH Pubhshers, New York, 1986. 

Spectrometric Analysis. Remarkable developments ia mass spectrometry (ms) and nuclear magnetic resonance methods (nmr), eg, secondary ion mass spectrometry (sims), plasma desorption (pd), thermospray (tsp), two or three dimensional nmr, high resolution nmr of soHds, give useful stmcture analysis information (131). Because nmr analysis of or N-labeled amino acids enables determiaation of amino acids without isolation from organic samples, and without destroyiag the sample, amino acid metaboHsm can be dynamically analy2ed (132). Proteia metaboHsm and biosynthesis of many important metaboUtes have been studied by this method. Preparative methods for labeled compounds have been reviewed (133). 

High Resolution NMR Spectra Catalog, Vol. 2, Spectrum No. 464, Vadan Assoc., Palo Alto, Calif., 1963. 

Indirect or scalar coupling of nuclear spins through covalent bonds causes the splitting of NMR signals into multiplets in high-resolution NMR spectroscopy in the solution state. The direct or... 

M. Mehring. Principles of High Resolution NMR in Solids. Springer Verlag,... 

R. R. Ernst (Eidgenbssische Technische Hochschule, Zurich) contributions to the development of the methodology of high resolution nmr spectroscopy. 

With the new very high resolution NMR spectra, it should be a simple matter to assign configurations to other difficult cyclitols or carbohydrates, for example, the numerous still undiscovered isomers of 6-bromo, 6-chloro, and 6-iodoquercitol (20 diastereomers predicted for each). 

Axelson DE (1986) in Komoroski (ed) High-resolution NMR spectroscopy of synthetic polymers in bulk. VCH, Weinheim, Chaps. 5 and 6... 

Those who deserve particular mention as pioneers in the field of the solid state high resolution NMR, are Schaefer5), Stejskal6), and Schneider and Doskocilova 7) and Lippmaa 8) and their co-workers. 

U. Haeberlen. High Resolution NMR in Solids. Academic Press, New York, 1976. 

Electron relaxation times are important parameters that allow us to predict whether high-resolution NMR is feasible. The two most im-... 

A field of application of MD that is beginning to bear fruit is the refinement of data from nuclear magnetic resonance (NMR) and from diffraction experiments. High-resolution NMR at frequencies around 500 MHz is able to resolve individual proton resonances of biological macromolecules in solution with molecular weights exceeding 10,000... 

The structures of many oligosaccharide chains can be elucidated by gas-liquid chromatography, mass spectrometry, and high-resolution NMR spectrometry. Glycosidases hydrolyze specific linkages in oligosaccharides and are used to explore both the structures and functions of glycoproteins. 

Hatcher PG, JM Bortiatynski, RD Minard, J Dec, J-M Bollag (1993) Use of high-resolution NMR to examine the enzymatic covalent binding of C-labeled 2,4-dichlorophenol to humic substances. Environ Sci Technol 21 2098-2103. 

Reif, B., Hennig, M., Griesinger, C. Direct measurement of angles between bond vectors in high-resolution NMR. Science im, 276,1230-1233. 

TABLE 3 High -Resolution NMR Parameters Providing Static and Dynamic Information on Lipid Bilayers... 

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