The Direct Determination of Protein Structure from Multidimensional NMR Spectra without Assignment

Abstract

Since the advent of multidimensional NMR (Jeener, 1971; Aue et al., 1976; Ernst et al., 1986) and its application to the study of biological macromolecules (Wuthrich, 1986), detailed analysis of the spectra of such molecules has allowed the investigation of the structure, dynamics and interactions of proteins, nucleic acids, etc. at the atomic level (Oppenheimer and James, 1989). It is widely assumed that assignment of NMR spectra is a prerequisite for the interpretation of spectra in structural and dynamic terms. Here, we show that structural information may be extracted directly from NMR spectra without assignment and that the molecular structure is independent of the assignment. The assignment of the resonances is then a useful, but not essential, by-product of the procedure providing additional information for refinement and subsequent investigation of dynamics and interactions. We discuss the implications and the problems that need to be overcome for the application of the approach and we suggest that some of the approaches to the interpretation of data used in X-ray crystallography may find parallels in the determination of structures by NMR.