Rapid NMR assignments of intrinsically disordered proteins using two-dimensional 13 C-detection based experiments.

An approach for rapid backbone resonance assignments in proteins using only two 2D NMR experiments is presented. The new method involves a combination of high-resolution C-13(alpha)-detected NMR experiments and selective unlabeling of amino acid residues. The C-13 detected 2D hNCA and 2D hNcoCA spectra of a uniformly labeled sample of the protein are analysed in concert with the 2D hNCA spectrum obtained for a selectively unlabeled sample. The combinatorial set of amino acid residues for selective unlabeling is chosen optimally to maximize the assignments. The method is useful for rapid assignment of proteins with low stability such as intrinsically disordered proteins and is applicable to deuterated proteins. This approach helped in assignments of 14.5 kDa human alpha-synuclein during the course of its aggregation.