NMR of intrinsically disordered proteins: A note on the application of 15N-13Cα het-TOCSY mixing for 13Cα magnetisation transfers.

Intrinsically disordered proteins (IDPs) or protein regions represent functionally important biomolecules without unique structure. Their inherent flexibility prevents high-resolution structure determination by X-ray or cryo-EM methods. In contrast, NMR spectroscopy provides an extensive and still growing set of experimental approaches to obtain detailed information on structure and dynamics of IDPs. Here, it is experimentally demonstrated that 15N-13Cα band-selective heteronuclear cross-polarisation that has been successfully employed recently to achieve the efficient transfer of 15Nx magnetisation from amino acid residue 'i' to 'i + 1' and 'i - 1' residues in uniformly (15N,13C)-labelled intrinsically disordered proteins can also be applied to transfer, without significant relaxation losses, 13Cαx magnetisation from an amino acid residue to its neighbouring residues. The possibility to obtain in one-shot correlation spectra arising from the simultaneous transfer of 15Nx and 13Cαx magnetisations from an amino acid residue to neighbouring residues is also demonstrated.