Identification of bound waters in the solution structure of ribonuclease T1 using the double pulsed field gradient spin‐echo NMR technique for selective water excitation

Novel pulse sequences incorporating the double pulsed field gradient spin‐echo technique are presented that have particular use in identifying macromolecular bound water. The use of these sequences is illustrated using ribonuclease T₁. Five amide protons cross‐relaxing with bound water protons were observed. Examination of the crystal structure revealed that all of these amide protons donate hydrogen bonds or are in close proximity to water molecules with very low temperature factors, indicating that these amide protons are highly correlated with the bound water molecules. This method rapidly provides reliable information for characterizing macromolecular bound water molecules. Copyright © 2002 John Wiley & Sons, Ltd.