The Transferred NOE

Abstract

The transferred NOE allows NOE information to be obtained on a bound ligand, but appearing on the resonances of the free ligand. It is thus a very useful method for gaining information on the bound ligand. Its major limitation is that it only works well in a range of dissociation constants between 1 mM and 10 nM. A key negative control experiment is to demonstrate the absence of NOEs arising from nonspecific binding, by addition of competitor ligands. A second is to measure NOEs in the absence of protein. For quantitative work, it is also necessary to minimize spin diffusion, by using relatively short mixing times. Recent work has shown that spin diffusion in TRNOE is no worse than spin diffusion in standard NOE spectra of proteins. With care, TRNOE can thus provide powerful quantitative information on bound conformation.