New (15)N NMR exchange experiments for the unambiguous assignment of (1)H(N)/(15)N resonances of proteins in complexes in slow chemical exchange with free form.

The potentialities of a 2D proton-detected heteronuclear exchange experiment to assign the nitrogen and amide proton resonances in a uniformly (15)N-enriched macromolecule involved in a complex, starting from the free form assignments, are demonstrated on a protein-DNA complex. This 2D experiment is further extended to a 3D experiment in the case of severe superpositions. Copyright 2000 Academic Press.