Pulse field gradient conformation

These calculated intracrystalline diffusion coefficients are particularly appropriate for comparison with those determined from pulsed field gradient (PFG) NMR experiments. Time-independent equilibrium properties such as adsorbate conformations are also readily accessible. The classical nature of the simulations allows a particle s trajectory to be followed, and from this it is possible to determine all kinds of information, such as how often a particle diffuses through a certain region. 

Packer and Rees [3] extended the work of Tanner and Stejskal by the development of a theoretical model using a log-normal size distribution function. Measurements made on two water-in-oil emulsions are used to obtain the self-diffusion coefficient, D, of the water in the droplets as well as the parameters a and D0 0. Since then, NMR has been widely used for studying the conformation and dynamics of molecules in a variety of systems, but NMR studies on emulsions are sparse. In first instance pulsed field gradient NMR was used to measure sdf-diffusion coefficients of water in plant cells (e.g. ref. [10]). In 1983 Callaghan... 

Protein conformational changes induced by metallodrug binding could be studied by pulsed-field gradient diffusion NMR spectroscopy, circular dichroism (CD) or fluorescence spectra. Covalent binding of cisplatin to the Ca " -binding protein calmodulin (CaM) was shown to induce a near complete collapse in the protein secondary structures, and resulted in a decrease of hydrodynamic radius to 21.4 0.2 A from 24.5 0.4 A for the... 

Judeinstein et al have conducted direct measurement of through-space NMR interactions that provide definitive evidence for spatial proximity of different species. Dipole-dipole interactions can be measured in principle between any NMR active nuclei with heteronuclear correlation experiments in the liquid or solid state." The dipole-dipole interactions decay quickly with the internuclear distances (r ), and are difficult to evaluate for long-range distances and even more difficult when exchange, conformation, or motion phenomena are present. However, the measurement of the nuclear Overhauser method" based on the dipole-dipole-induced crossrelaxation, was proposed to successfully measure intermolecular interactions" and the formation of ion pairs." " In agreement with recent studies, the pulsed field gradient enhanced inverse HOESY (heteronuclear Overhauser enhancement spectroscopy) sequence is usually preferred because it is more sensitive for isotope pairs H- Li and also improves the digital resolution in the H crowded spectrum." ... 

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