Transferred nuclear Overhauser effect

Rao, B. D. N. Two-dimensional transferred nuclear Overhauser effect spectroscopy (TRNOESY) smdies of nucleotide conformations in creatine kinase complexes effects due to weak nonspedftc binding. Biochemistry 1993,... 

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. 

Guichard, G., Briand, J. P., Muller, S., Cung, M. T. Structure of antibody-bound peptides and retro-inverso analogues. A transferred nuclear Overhauser effect spectroscopy and molecular dynamics approach. Biochemistry 2001, 40, 5720-5727. 

As with the COSY experiment, the sequence starts with a pulse followed by an evolution period, but now the mechanism that couples the two spins (which must be in close proximity, typically <6 A) is the Nuclear Overhauser Effect (NOE). The second pulse converts magnetization into population disturbances, and cross-relaxation is allowed during the mixing time. Finally, the third pulse transfers the spins back to the x-y-plane, where detection takes place. The spectrum will resemble a COSY spectrum, but the off-diagonal peaks now indicate through-space rather than through-bond interactions. 

The observed polarization is primarily associated with the former parahydrogen protons. However, other protons may also experience a drastic signal enhancement due to nuclear spin polarization transferred to these nuclei via the nuclear Overhauser effect (NOE) or similar processes, both in the final reaction products as well as in their precursor intermediates. 

Another, yet completely different access to macroscopic binding strengths of selectands on CSPs has been described by Hellriegel et al. [65] employing suspended-state NMR spectroscopy. Thus, HR-MAS 2D transfer-nuclear Overhauser effect spectroscopy (NOESY) was utilized to distinguish solutes strongly binding to the... 

TTie TOCSY 2D NMR experiment correlates all protons of a spin system, not just those directly connected via three chemical bonds. For the protein example, the alpha proton, Ft , and all the other protons are able to transfer magnetization to the beta, gamma, delta, and epsilon protons if they are connected by a continuous chain—that is, the continuous chain of protons in the side chains of the individual amino acids making up the protein. The COSY and TOCSY experiments are used to build so-called spin systems—that is, a list of resonances of the chemical shift of the peptide main chain proton, the alpha proton(s), and all other protons from each aa side chain. Which chemical shifts correspond to which nuclei in the spin system is determined by the conventional correlation spectroscopy connectivities and the fact that different types of protons have characteristic chemical shifts. To connect the different spin systems in a sequential order, the nuclear Overhauser effect spectroscopy... 

Hence, provided that I g is known and that R has been determined by means of an independent experiment, provides the cross-relaxation rate ct. This enhancement is called nuclear Overhauser effect (nOe) (17,19) from Overhauser (20) who was the first to recognize that, by a related method, electron spin polarization could be transferred to nuclear spins (such a method can be worked out whenever EPR lines are relatively sharp it is presently known as DNP for Dynamic Nuclear Polarization). This effect is usually quantified by the so-called nOe factor p... 

Chemical shift correlated NMR experiments are the most valuable amongst the variety of high resolution NMR techniques designed to date. In the family of homonuclear techniques, four basic experiments are applied routinely to the structure elucidation of molecules of all sizes. The first two, COSY [1, 2] and TOCSY [3, 4], provide through bond connectivity information based on the coherent (J-couplings) transfer of polarization between spins. The other two, NOESY [5] and ROESY [6] reveal proximity of spins in space by making use of the incoherent polarization transfer (nuclear Overhauser effect, NOE). These two different polarization transfer mechanisms can be looked at as two complementary vehicles which allow us to move from one proton atom of a molecule to another proton atom this is the essence of a structure determination by the H NMR spectroscopy. 

Lin, Y Nageswara Rao, B.D. Structural characterization of adenine nucleotides bound to Escherichia coli adenylate kinase. 1. adenosine conformations by proton two-dimensional transferred nuclear overhauser effect spectroscopy. Biochemistry, 39, 3636-3646 (2000)... 

More quantitative information about host-guest proximity may be obtained by application of the nuclear overhauser effect (NOE). Very simply, the NOE involves the saturation of the spin of one nucleus by continuous irradiation, and monitoring the resulting intensity enhancements of the NMR resonances of adjacent atoms. The idea is that the irradiation of one nucleus causes it to become excited to a nonequilibrium distribution of spin states. Relaxation of this excited state situation occurs by dipole-dipole spin-lattice transfer of the excess energy, resulting in enhancement of the intensity of signals for nuclei physically close to the irradiated nucleus, irrespective of whether they are actually bonded. NOE intensity enhancements may be anywhere... 

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