Editing of chemical exchange-relayed NOEs in NMR experiments for the observation of protein-water interactions

An experimental approach for the editing of exchange-relayed NOEs in water- selective NOE experiments is presented. The proposed pulse sequence is base d on the application during the NOE mixing time of continuous wave irradiat ion, which saturates resonances of relaying labile protons in slow chemical exchange with water. The technique can efficiently reduce the contribution s of exchange-relayed NOE peaks that often crowd the water-selective NOE sp ectra and hide direct intermolecular NOEs between water and protein protons . The present approach opens new opportunities for the characterization of hydration by NMR, even in the proximity of polar labile groups, (C) 1999 Ac ademic Press.