In this paper, the recently developed ''Water-PRESS'' method the water resonance independently of the solute resonances of water suppression [W. S. Price and Y. Arata (1996), J. Magn. in the frequency domain. Reson. B 112, 190] in which homospoil pulses are used to manipulate the effects of radiation damping on the water resonance and Traditional Means of Water Suppression and thereby selectively alter the effective relaxation times of the water Complications resonance with respect to the solute (e.g., biological macromolecules) resonances is further developed and applied. In the present Many water-suppression methods exist, including presatuwork, methods for optimization in terms of degree of water supration, relaxation-based techniques, selective-excitation, grapression and in temporal terms (important for the application of dient, and combined selective-excitation-gradient-based Water-PRESS to multidimensional experiments) are considered methods. Most of these methods have been recently reso that recycle delays of less than 2.3 s (including the acquisition viewed (3-7). The selectivity to the water resonance and time) are possible. Also, a simple modification which allows the the degree of suppression of these methods are diminished observation of solute resonances with relaxation times similar to by a combination of five factors: (1) radiation damping, (2) that of the water resonance is presented. Finally, the inclusion into selective pulses are not perfectly selective and generally do more complicated pulse sequences is also discussed. Experimental examples using aqueous samples of lysozyme and immunoglobulin not have a pure phase, (3) inhomogeneity of the RF (i.e., are given. Compared to most other NMR water suppression tech-B 1 ) and static magnetic (i.e., B 0 ) fields, (4) spin diffusion, niques, this method is extremely simple to implement and optimize and (5) due to radiation damping, the water resonance has and does not require accurately calibrated RF pulses or perfect an effective relaxation time close to that of the protein resolineshape. ᭧ 1997 Academic Press nances.
The use of selective-excitation (3, 4) and gradient-based methods involving selective RF pulses [e.g., WATERGATE (8,9), flipback (10), WET (11,12),