NEW PULSED-FIELD GRADIENT NMR EXPERIMENTS FOR THE DETECTION OF BOUND WATER IN PROTEINS

New H2O-selective homonuclear and heteronuclear 2D NMR experiments hav e been designed for the observation of protein hydration (PHOGSY, Prot ein Hydration Observed by Gradient SpectroscopY). These experiments ut ilize selective excitation of the H2O resonance and pulsed field gradi ents for coherence selection and efficient H2O suppression. The method allows for a rapid and sensitive detection of H2O molecules in labell ed and unlabelled proteins. In addition, it opens a way to measure the residence time of water bound to proteins. Its application to uniform ly N-15-labelled FKBP-12 (FK-506 binding protein) is demonstrated.