NMR spectroscopy remains the only experimental technique that provides (near) atomistic structural information for intrinsically disordered proteins (IDPs), but their sequence and structure characteristics still pose major challenges for high-resolution spectroscopy. Carbon-13 direct-detect NMR spectroscopy can overcome poor spectral dispersion and other difficulties associated with traditional 1H-detected NMR of nonaggregating disordered proteins. This chapter presents spectroscopic protocols suitable for complete characterization of IDPs that rely exclusively on 13C direct-detect experiments. The protocols described span initial characterization and chemical shift assignment; structure constraint through residual dipolar coupling and paramagnetic relaxation enhancement measurements; and assessment of intramolecular dynamics through 15N spin relaxation. The experiments described empower investigators to establish molecular mechanisms and structure-function relationships for IDPs and other proteins characterized by high internal flexibility.
Keywords: Chemical shift assignment; Intrinsically disordered protein; Nuclear magnetic resonance; Posttranslational modification.
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