Nuclear magnetic resonance cross relaxation

Werbelow L G 1996 Relaxation processes cross correlation and interference terms Encyclopedia of Nuclear Magnetic Resonance ed D M Grant and R K Harris (Chichester Wiley) pp 4072-8... 

Specinfo, from Chemical Concepts, is a factual database information system for spectroscopic data with more than 660000 digital spectra of 150000 associated structures [24], The database covers nuclear magnetic resonance spectra ( H-, C-, N-, O-, F-, P-NMR), infrared spectra (IR), and mass spectra (MS). In addition, experimental conditions (instrument, solvent, temperature), coupling constants, relaxation time, and bibliographic data are included. The data is cross-linked to CAS Registry, Beilstein, and NUMERIGUIDE. 

B. D. Sykes, W. E. Hull, and G.H. Snyder, Biophys. /, 21, 137 (1978). Experimental Evidence for the Role of Cross-relaxation in Proton Nuclear Magnetic Resonance Spin Lattice Relaxation Time Measurements in Proteins. 

In a paper that appeared in 1979, R.P.J. Merks and R. DeBeer pointed out that the sinusoidal dependence of the stimulated echo ESEEM experiment on x and T (equation 8), presented the opportunity to collect ESEEM data in both time dimensions and then apply a two-dimensional EFT to derive two important benefits. The first benefit was that suppression-free spectra should be obtained along the zero-frequency axis for each dimension while the second benefit would be the appearance of cross-peaks at (tUo, cofs) and (tw, co ) that would allow one to identify peaks that belonged to the same hyperfine interaction. This ESEEM version of the NMR COSY experiment (see Nuclear Magnetic Resonance (NMR) Spectroscopy of Metallobiomolecules) would prove invaluable for ESEEM analysis of complex spin systems. However, the disparity in spin relaxation times in the x and T time dimensions precluded the general application of this method. 

Palmer, A. R. and Maciel, G. E. (1982). Relaxation behavior in the carbon-13 nuclear magnetic resonance spectrometric analysis of kerogen with cross-polarization and magic-angle spinning. Anal. Chem. 54, 2194-2198. 

Vodovotz, Y, Dickinson, L.C., and Chinachoti, P. Molecular characterization around a glassy transition of starch using H-1 cross-relaxation nuclear magnetic resonance, /. Agric. Food Chem., 48, 4948, 2000. 

The addition of a chemical species with a large dielectric constant to induce desired microwave effects in matrices devoid of such substances, or lacking substances with significantly different dielectric constants, can be compared, on a conceptual basis, to cross-polarisation experiments carried out in nuclear magnetic resonance spectroscopy (see Chapter 6). In that case, a nucleus that relaxes relatively rapidly is excited selectively and allowed to transfer that excitation energy to neighbouring nuclei with low or relatively lower relaxation rate (e.g., nuclei being cross-polarised to nuclei). 

Interest in water at protein surfaces and other surfaces arises from a desire to understand structural, functional, and dynamic factors as well as their interrelationships. Nuclear magnetic resonance (NMR) spectroscopy provides both structural and dynamic information. This presentation will focus on dynamical aspects of the water-protein Interaction. In particular, the phenomenon of cross relaxation between the water and protein proton systems will be discussed and new evidence will be reported. Failure to recognize the importance of cross relaxation effects leads to incorrect conclusions about the dynamics of water at protein surfaces. 

Nuclear Overhauser effect (NOE), the transfer of spin polarization from one spin population to another by cross-relaxation in nuclear magnetic resonance spectroscopy. The NOE in, e.g., NOESY spectra can be used to derive distance information between two nuclei in a molecule and, hence, serves as a tool for structure elucidation. 

In Spectral Methods in Food Analysis (M.M. Mossoba, ed.), pp. 1-88. Dekker, New York. Eads, T.M. and Axelson, D.E. 1995. Nuclear cross relaxation spectroscopy and single point imaging measurements of solids and solidity in foods. In Magnetic Resonance in Food Science (P.S. Belton, F Delgadillo, A.M. Gil, and G.A. Webb, eds), pp. 230-242. Royal Society of Chemistry, Cambridge, UK. 

Exchange of magnetization due to cross-relaxation (NOE, nuclear Overhauser effect) does lead to intensity changes of individual resonances which provide valuable information about spatial and motional characteristics of the spins involved [4, 5]. It is currently mostly measured in two-dimensional NMR, where the NOE is measured as cross-peak intensity. Cross-relaxation is caused by mutual spin flips in dipolar coupled spin pairs. 

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