Topic
Relaxation (NMR)
About: Relaxation (NMR) is a research topic. Over the lifetime, 29342 publications have been published within this topic receiving 689851 citations.
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01 Jan 2006
TL;DR: In this paper, the Density Matrix and Product Operator of Coupled Spins were used to acquire one-dimensional NMR spectra. But the number of dimensions was not defined.
Abstract: List of Figures. List of Tables. 1. Introduction To NMR Spectroscopy. 2. Acquiring One-Dimensional Spectra. 3. Processing One-Dimensional Spectra. 4. Quantum Mechanical Description Of NMR. 5. Quantum Mechanical Description Of A One Pulse Experiment. 6. The Density Matrix. 7. Scalar Coupling. 8. Density Matrix And Product Operator of Coupled Spins. 9. Two Dimensional J-Correlations. 10. Heteronuclear J-Correlation Spectroscopy. 11. Coherence Editing. 12. Quadrature Detection In two Dimensional NMR Spectroscopy. 13. Exchange Processes. 14. Nuclear Spin Relaxation. 15. Resonance Assignments: Homonuclear Methods. 16. Resonance Assignments: Heteronuclear Methods. 17. Practical Aspects of N-Dimensional Data Acquisition And Processing. 18. Dipolar Coupling. 19. Protein Structure Determination. Appendices: A Fourier Transforms. B Complex Variables. C Solving Simultaneous Differential Equations: Laplace Transforms. Index.
185 citations
TL;DR: In this paper, a fast exchange two-state model with local anisotropy was used to study protein hydration in aqueous solutions of seven proteins, including carboxylate.
Abstract: Water oxygen-17 magnetic relaxation is shown to be a powerful technique for studying protein hydration. Longitudinal and transverse 170 relaxation rates were measured at variable frequency (4-35 MHz), temperature, pH, and protein concentration in aqueous solutions of seven proteins. The data were analyzed in terms of a fast exchange two-state model with local anisotropy. A water 170 quadrupole coupling constant of 6.67 MHz and an order parameter of 0.06 (from I7O splittings in lyotropic liquid crystals) results in approximately two layers of hydration water having a reorientational rate less than 1 order of magnitude slower than that of bulk water. This rapid local motion has a small anisotropic component, which is averaged out by protein reorientation with a correlation time of the order of 10 ns. Due to electrostatic protein-protein interaction the protein reorientation is considerably slower than predicted by the Debye-Stokes-Einstein equation. Charged residues, particularly carboxylate, are more extensively hydrated than other residues, accounting for the variation in the extent of hydration between different proteins.
185 citations
TL;DR: The detailed theory of an experiment which uses magnetic field cycling to observe slow singlet relaxation is provided, using a model of intramolecular dipole-dipole couplings and fluctuating external random fields.
Abstract: We have recently demonstrated the existence of exceptionally long-lived nuclear spin states in solution-state nuclear magnetic resonance The lifetime of nuclear spin singlet states in systems containing coupled pairs of spins-1∕2 may exceed the conventional relaxation time constant T1 by more than an order of magnitude These long lifetimes may be observed if the long-lived singlet states are prevented from mixing with rapidly relaxing triplet states In this paper we provide the detailed theory of an experiment which uses magnetic field cycling to observe slow singlet relaxation An approximate expression is given for the magnetic field dependence of the singlet relaxation rate constant, using a model of intramolecular dipole-dipole couplings and fluctuating external random fields
184 citations
TL;DR: The effects of anisotropy of rotational diffusion and extent of dimerization on the performance of the simple and extended model-free formulas are investigated and none of the three model- free approaches tested yields reliable internal motion parameters.
183 citations
TL;DR: In this article, the authors considered the case that the motion of the system is on a single potential energy surface and the case where this motion occurred on two surfaces was considered elsewhere.
Abstract: Intramolecular charge transfer are considered for the case that the motion of the system is on a single potential energy surface. The case where this motion occurred on two surfaces was considered elsewhere. The former is shown to be much preferable for studies of solvent dynamics. Several aspects of the relation between ‘‘constant charge’’ dielectric relaxation time of the polar solvent and the experimental decay time of emission from the polar excited state of the solute are discussed for hydrogen‐bonded systems.
183 citations