Exclusively Heteronuclear 13C-Detected Amino-Acid-Selective NMR Experiments for the Study of Intrinsically Disordered Proteins (IDPs)

Carbon-13 direct-detection NMR methods have proved to be very useful for the characterization of intrinsically disordered proteins (IDPs). Here we present a suite of experiments in which amino-acid-selective editing blocks are encoded in CACON- and CANCO-type sequences to give C-13-detected spectra containing correlations arising from a particular type or group of amino acid(s). These two general types of experiments provide the complementary intra- and inter-residue correlations necessary for sequence-specific assignment of backbone resonance frequencies. We demonstrate the capabilities of these experiments on two IDPs: fully reduced Cox17 and WIPC. The proposed approach constitutes an independent strategy to simplify crowded spectra as well as to perform sequence-specific assignment, thereby demonstrating its potential to study IDPs.