The direct determination of protein structure by NMR without assignment

Assignment of the resonances in nuclear magnetic resonance spectra is considered a pre-requisite for the interpretation of spectra that yield structural information. The determination of the three-dimensional structure of a biological macromolecule may, however, be achieved directly without spectral assignment, using the same set of heteronuclear scalar and dipolar coupling experiments as normally used. A cross-peak in any of the spectra may be interpreted as a distance between atoms, yielding a set of distances between unassigned atoms that serves to define the tertiary structure of the molecule. The principle is illustrated using the 76 amino acid protein ubiquitin. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.