Triple‐Resonance NMR Experiments for Assignment of Asparagine and Glutamine Side‐Chain NH ₂ Groups in Intrinsically Disordered Proteins

Complete degeneracy of aliphatic 13 C chemical shifts of the same type of amino‐acid residues precludes unambiguous NMR assignments of asparagine (Asn) and glutamine (Gln) carboxamide NH 2 groups in intrinsically disordered proteins with conventional techniques. Here, a pair of triple‐resonance NMR experiments is described that correlate the 1 H/ 15 N chemical shifts of Asn and Gln carboxamide NH 2 groups with the backbone amide 15 N chemical shifts of the same and the next residue. These experiments exploit a by far superior dispersion of backbone amide 15 N chemical shifts, and permit unambiguous assignments of all Asn/Gln side‐chain NH 2 groups in the intrinsically disordered protein α ‐synuclein and the majority of Gln NH 2 groups in the disordered huntington exon‐1 protein with a 7‐residue glutamine repeat, htt ex1 Q 7 .