Protonless NMR experiments for sequence-specific assignment of backbone nuclei in unfolded proteins.

Natively unfolded proteins are increasingly recognized to play important physiological roles. These proteins do not crystallize, so NMR is the only technique able to provide structural and dynamic information. However, in unfolded proteins, the proton chemical shift dispersion is poor, causing severe problems in resonance assignment. We designed a novel strategy based on two protonless experiments, a CBCACON-IPAP and a novel COCON-IPAP, that permits a straightforward and unequivocal backbone heteronuclear assignment of the natively unfolded protein alpha-synuclein.