A procedure is presented for the substantial simplification of 2D constant-time ¹³C−¹H heteronuclear single-quantum correlation (HSQC) spectra of ¹³C-enriched proteins. In this approach, a single pulse sequence simultaneously records eight sub-spectra wherein the phases of the NMR signals depend on spin topology. Signals from different chemical groups are then stratified into different sub-spectra through linear combination based on Hadamard encoding of ¹³CH_n multiplicity (n = 1, 2, and 3) and the chemical nature of neighboring ¹³C nuclei (aliphatic, carbonyl/carboxyl, aromatic). This results in five sets of 2D NMR spectra containing mutually exclusive signals from: (i) ¹³C^β−¹H^β correlations of asparagine and aspartic acid, ¹³C^γ−¹H^γ correlations of glutamine and glutamic acid, and ¹³C^α−¹H^α correlations of glycine, (ii) ¹³C^α−¹H^α correlations of all residues but glycine, and (iii) ¹³C^β−¹H^β correlations of phenylalanine, tyrosine, histidine, and tryptophan, and the remaining (iv) aliphatic ¹³CH₂ and (v) aliphatic ¹³CH/¹³CH₃ resonances. As HSQC is a common element of many NMR experiments, the spectral simplification proposed in this article can be straightforwardly implemented in experiments for resonance assignment and structure determination and should be of widespread utility.

提出了一种程序，用于显着简化¹³ C 富集蛋白质的 2D 恒定时间¹³ C- ¹ H 异核单量子相关 (HSQC) 光谱。在这种方法中，单个脉冲序列同时记录八个子光谱，其中 NMR 信号的相位取决于自旋拓扑。然后通过基于¹³ CH _n多重性（n  = 1、2 和 3）的Hadamard 编码和相邻¹³C 核（脂肪族、羰基/羧基、芳香族）。这导致五组 2D NMR 光谱包含来自以下方面的互斥信号：(i)天冬酰胺和天冬氨酸的¹³ C ^β - ¹ H ^β相关性，谷氨酰胺和谷氨酸的¹³ C ^γ - ¹ H ^γ相关性，以及¹³ C ^α − ¹甘氨酸的H ^α相关性，(ii)除甘氨酸外所有残基的¹³ C ^α − ¹ H ^α相关性，以及 (iii) ¹³ C ^β − ¹苯丙氨酸、酪氨酸、组氨酸和色氨酸以及剩余的 (iv) 脂肪族¹³ CH ₂和 (v) 脂肪族¹³ CH/ ¹³ CH ₃共振的H ^β相关性。由于 HSQC 是许多 NMR 实验的常见元素，本文中提出的光谱简化可以直接在共振分配和结构确定实验中实施，并且应该具有广泛的实用性。