Relaxation-Matrix Formalism for Rotating-Frame Spin-Lattice Proton NMR Relaxation and Magnetization Transfer in the Presence of an Off-Resonance Irradiation Field
| Autor: | Kazuo Kuwata, D. Brooks, Thomas Schleich, Hua Yang |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
Phase transition
Magnetic Resonance Spectroscopy Macromolecular Substances Chemistry Gaussian General Engineering Spin–lattice relaxation Analytical chemistry Water Models Theoretical Carbon-13 NMR Crystallins Molecular physics Dilution Magnetics symbols.namesake Body Water Lens Crystalline Curve fitting Proton NMR symbols Animals Cattle Magnetization transfer Protons |
| Zdroj: | Journal of Magnetic Resonance, Series B. 104:11-25 |
| ISSN: | 1064-1866 |
| DOI: | 10.1006/jmrb.1994.1049 |
| Popis: | The derivation of a generalized relaxation matrix equation for the off-resonance rotating-frame spin-lattice experiment, representing N macromolecular components, is presented. The applicability of the derived formalism was demonstrated using water proton off-resonance rotating-frame spin-lattice relaxation data obtained for calf lens cortical and nuclear homogenates, a tissue system characterized by the presence of both mobile and solid-like protein domains, whose relative amounts vary in a protein-concentration-dependent manner. Protein concentration and temperature were utilized as variables in the magnetization-transfer experiments. Curve fitting to obtain the relevant magnetization-transfer parameters was accomplished by simulated annealing and the method of steepest descents. In all cases, the best fit, as reflected by the smallest root-mean-square deviation, was obtained by assuming the presence of three components representing bulk-water and mobile and solid-like macromolecular components, characterized by Lorentzian (water and mobile protein) and Gaussian proton resonance lineshapes (solid-like protein). A two-component relaxation model gave unsatisfactory fits. Dilution of nuclear homogenate resulted in physically realistic changes in the derived magnetization-transfer parameters, which included a decrease in the fraction of solid-like,protein, in agreement with previously published 13 C NMR studies. Changes in magnetization-transfer parameters occurred as a result of the cold cataract phase transition in nuclear homogenate. The utility and limitations of the derived formalism are discussed. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|