Nuclear Overhauser effect analysis

Neuhaus D and Williamson M 1989 The Nuclear Overhauser Effect in Structural and Conformational Analysis (New York VCH)... 

Another technique often used to examine the stmcture of double-heUcal oligonucleotides is two-dimensional nmr spectroscopy (see AfAGNETiC SPIN resonance). This method rehes on measurement of the nuclear Overhauser effects (NOEs) through space to determine the distances between protons (6). The stmcture of an oligonucleotide may be determined theoretically from a set of iaterproton distances. As a result of the complexities of the experiment and data analysis, the quality of the stmctural information obtained is debated. However, nmr spectroscopy does provide information pertaining to the stmcture of DNA ia solution and can serve as a complement to the stmctural information provided by crystallographic analysis. 

One-dimensional nuclear Overhauser effect (NOE), relaxation measurements in native D. gigas Fdll, and analysis of temperature depen-... 

Neuhaus, D., and Williamson, M. (1989). The nuclear Overhauser effect in structural and confirma-tional analysis. VCH Pubs., New York, p. 278. 

Clore, G. M., Gronenbom, A. M. Theory of the time dependent transferred nuclear Overhauser effect applications to stmctural analysis of ligand-protein complexes in solution. J. Magn. Reson. 1983, 53, 423 2. 

Conformational analysis of oligosaccharides in solution by NMR is mainly based on hydrogen-hydrogen distance information obtained from the nuclear Overhauser effect (n.O.e.) ( ). Other independent NMR... 

It is not usually possible to integrate routine C spectra directly unless specific precautions have been taken. However with proper controls, NMR spectroscopy can be used quantitatively and it is a valuable technique for the analysis of mixtures. To record C NMR spectra where the relative signal intensity can be reliably determined, the spectra must be recorded with techniques to suppress the Nuclear Overhauser Effect and with a long delay between the acquisition of successive spectra to ensure that all of the carbons in the molecule are completely relaxed between spectral acquisitions. 

H is particularly important in NMR experiments because of its high sensitivity and natural abundance. For macromolecules, 1H NMR spectra can become quite complicated. Even a small protein has hundreds of 1H atoms, typically resulting in a one-dimensional NMR spectrum too complex for analysis. Structural analysis of proteins became possible with the advent of two-dimensional NMR techniques (Fig. 3). These methods allow measurement of distance-dependent coupling of nuclear spins in nearby atoms through space (the nuclear Overhauser effect (NOE), in a method dubbed NOESY) or the coupling of nuclear spins in atoms connected by covalent bonds (total correlation spectroscopy, or TOCSY). 

It is possible to distinguish a 4,5-trans-disubstituted oxazolidinone or imidazolidinone from its 4,5-ds-analogue by using H NMR analysis. Indeed, both H4 and H5 protons resonate systematically at lower field for the ds-isomer than for the trans-isomer, and higher /4i5 coupling constants are observed for the ds-oxazolidinones (Table 8). In addition, nuclear Overhauser effect (NOE) enhancement experiments confirm the cis or trans relationship of the H4 and H5 protons. 

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