Amide-Exchange-Rate-Edited Nmr (Aere-Nmr) Experiment: A Novel Method For Resolving Overlapping Resonances

This paper describes an amide-exchange-rate-edited (AERE) NMR method that can effectively alleviate the problem of resonance overlap for proteins and peptides. This method exploits the diversity of amide proton exchange rates and consists of two complementary experiments: (1) SEA (solvent exposed amide)-type NMR experiments to map exchangeable surface residues whose amides are not involved in hydrogen bonding, and (2) pre-sat-type NMR experiments to map solvent inaccessibly buried residues or nonexchangeable residues located in hydrogen-bonded secondary structures with properly controlled saturation transfer via amide proton exchanges with the solvent. This method separates overlapping resonances in a spectrum into two complementary spectra. The AERE-NMR method was demonstrated with a sample of N-15/C-13/H-2(70%) labeled ribosome-inactivating protein trichosanthin of 247 residues.