Abstract
Nuclear magnetic resonance spectroscopy (NMR) is a powerful technique for characterizing the structural and dynamic properties of intrinsically disordered proteins and protein regions (IDPs & IDRs). However, the application of NMR to IDPs has been limited by poor chemical shift dispersion in two-dimensional (2D) (1)H-(15)N heteronuclear correlation spectra. Among the various detection schemes available for heteronuclear correlation spectroscopy, (13)C direct-detection has become a mainstay for investigations of IDPs owing to the favorable chemical shift dispersion in 2D (13)C'-(15)N correlation spectra. Recent advances in cryoprobe technology have enhanced the sensitivity for direct detection of both (13)C and (15)N resonances at high magnetic field strengths, thus prompting the development of (15)N direct-detect experiments to complement established (13)C-detection experiments. However, the application of (15)N-detection has not been widely explored for IDPs. Here we compare (1)H, (13)C, and (15)N detection schemes for a variety of 2D heteronuclear correlation spectra and evaluate their performance on the basis of resolution, chemical shift dispersion, and sensitivity. We performed experiments with a variety of disordered systems ranging in size and complexity; from a small IDR (99 amino acids), to a large low complexity IDR (185 amino acids), and finally a ∼73 kDa folded homopentameric protein that also contains disordered regions (133 amino acids/monomer). We conclude that, while requiring high sample concentration and long acquisition times, (15)N-detection often offers enhanced resolution over other detection schemes in studies of disordered protein regions with low complexity sequences.