NUCLEAR MAGNETIC RESONANCE 1 Technique

Giusti, M.M., Ghanadan, H., and Wrolstad, R.E., Elucidation of the structure and conformation of red radish Raphanus sativus) anthocyanins using one- and two-dimensional nuclear magnetic resonance techniques, J. Agric. Food Chem., 46, 4858, 1998. 

A nucleus under study by nuclear magnetic resonance techniques is affected by other nuclei in the same molecule. This phenomenon is known as spin-spin coupling. The effect arises (in adjacent nuclei) from the two electrons joining the nuclei in a covalent bond. Suppose the energy of states in which the electrons in the bond have opposing spins is lower than the state in which the electron spins are parallel. Then the AE between the two states (in this case a negative number) is called the coupling constant, J, expressed in frequency units, Hz. Internuclear... 

A solution structure of French Bean plastocyanin has been reported by Wright and co-workers,19 using nuclear magnetic resonance techniques described in Section 3.5 of Chapter 3. The structure, determined from a plastocyanin molecule in solution rather than in a solid-state crystal, agrees well with that of reduced poplar plastocyanin X-ray crystallographic structure reported above. Conformations of protein side chains constituting the hydrophobic core of the French bean plastocyanin are well-defined by the NMR technique. Surface side chains show... 

O Brien, J. 1992. Application of nuclear magnetic resonance techniques in food research. Trends Food... 

A combination of GC-FTIR-MS is also being developed to provide an extremely powerful tool for identifying molecular markers [703, 704]. If sufficient quantities of individual molecular markers can be isolated, then there are various H [705, 706] and 13C nuclear magnetic resonance techniques [505,707-710] available to assist in their structural identification. 

Anomeric interconversion of sugars and their derivatives is typically relatively slow, but anomerization of phos-phorylated sugars is usually faster. Values for the rate constants can be obtained by nuclear magnetic resonance techniques. For example, the conversion of /3-fructose... 

Wong, Konizer, and Smid (42) find by a proton nuclear magnetic resonance technique that in the solvent tetrahydrofuran, dicyclohexyl-18-crown-6 binds the ion pair Na+, F (F = fluorenyl carbanion) more strongly than it does the K+, F ion pair. Although no K values are given they estimate log K to be larger than 10 for the reaction Na+, F + L = Na+, F L (L = dicyclohexyl-18-crown-6 or dimethyldibenzo-18-crown-... 

Abstract This chapter describes the experimentai compiement of theoretical models of the microscopic mechanism of ferroelectric transitions. We use the hydrogen-bonded compounds as examples, and attempt to show that the new experimental data obtained via recently developed high resolution nuclear magnetic resonance techniques for solids clearly support the hypothesis that the transition mechanism must involve lattice polarizability (i.e. a displacive component), in addition to the order/disorder behaviour of the lattices. 

The overall fold of a globular protein molecule in solution is likely to be given by the X-ray structure of the molecule in a crystal. This has been shown to be the case in detail for one protein, lysozyme, by means of nuclear magnetic resonance techniques, and is highly probable for others. It is necessary, however, to be aware that the conditions under which the protein is crystallized, or studied in solution, can affect the fold, and this has been illustrated with insulin. 

Andersen, 0.M., Opheim, S., Aksnes, D.W., and Frpystein, N.A. 1991b. Structure of petanin, an acylated anthocyanin isolated from Solanum tuberosum, using homo- and hetero-nuclear two-dimensional nuclear magnetic resonance techniques. Phytochem. Anal. 2 230-236. 

Mancuso, A., Fernandez, E.J., Blanch, H.W., Clark, D.S. (1990). A nuclear magnetic resonance technique for determining hybridoma cell concentration in hollow fibre bioreactors. Bio/Technol-ogy 8, 1282-1285. 

The different VCD spectra calculated for the NMR and X-ray structures demonstrate just how sensitive VCD is toward structural changes. It is premature, at this stage, to attempt to use VCD as a tool to distinguish or even judge the quality of either of the previously obtained structures. However, further computational efforts may well establish VCD as a complementary tool to NMR for the determination of solution conformation. VCD will certainly not challenge NMR in large molecules, where the superior resolution allows detailed structures to be derived. However, the much faster time frame of vibrational spectroscopy over nuclear magnetic resonance techniques allows distinct structures to be discerned when NMR measurements perceive little structure. 

In some instances, nuclear magnetic resonance techniques employing trimethylsilyl ethers have provided information on the composition of sugar solutions that could not be obtained by classical methods. Thus, the formation of D-galactofuranose during mutarotation was shown by gas chromatography of the trimethylsilyl derivatives of D-galactose (from the mutarotation mixture). The products were... 

Even after I gave up doing experiments in my own laboratory, when I was about 45, I continued as a consultant during the summers in the Los Alamos National Laboratory. Some of my work on the interaction of solvent water with metal ions was done at Los Alamos, using nuclear magnetic resonance techniques. I believe ours was something of a pioneering effort in that field. 

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