Contact Surface of Heme Proteins to Water Studied by NMR Method.

点击翻译按钮获取中文摘要

(1) NMR tubes with symmetric geometry: Based on the analyses of magnetic field distribution, NMR tubes with symmetric geometry was devised and tested. Prototype used small containers for the purpose of shim plugs. Difficulty in handling prompted to develop a simplified version using a special glass matched with the magnetic susceptibility of aqueous samples. After several trials, this simplified NMR microcell with symmetric geometry was successful and now commercially available.(2) A novel selective excitation method: There are not a few selective excitation pulse method each of which has its own drawbacks. The novel method makes use of 11 pulse method. On the contrary to the conventional 11 pulse method, this method uses as symmetric 11 pulses and takes a linear combination of 2 sets of spectra obtained from 11 pulses. This new method is free from a baseline roll and phase distortions. Moreover, signal suppression ratio is certainly better than that obtained by 1331 pulse method.(3) N … More on-selective complete saturation method: NMR measurements of X nuclei make use of non-selective saturation of protons. These methods turns out imperfect concerning to proton saturation itself. By applying progressive saturation pulse and Waugh pulse simultaneously, complete non-selective saturation was obtained. Residual proton resonances were less than 1%.(4) New relaxation mechanism for paramagnetic ions in aqueous solution: When small amount of paramagnetic ions are present in a non-deuterated aqueous solution, and when nuclear spins of H_2O signal is saturated, it was found that electron spins of paramagnetic ions are most likely perturbed. This phenomenon has been unknown so far in a liquid phase.(5) Selective observation of surface residues on macromolecules: Saturation recovery was conducted under the presence of small amount of paramagnetic species. This method enabled to observe quite unique selective signals from proteins in the vicinity of paramagnetic species. Thus, the signals observed have to be derived from the surface residues on the protein molecules. This method is universally applicable to any macromolecules in principle. Less