Resonance assignment of intrinsically disordered proteins is remarkably challenging due to scant chemical shift dispersion arising from conformational heterogeneity. The challenge is even greater if repeating segments are present in the amino acid sequence. To forward unambiguous resonance assignment of intrinsically disordered proteins, we present iHACANCO, HACACON and (HACA)CONCAHA, three Hα-detected 4D experiments with Cα as an additional dimension. In addition, we present (HACA)CON(CA)NH and (HACA)N(CA)CONH, new 4D Hα-start, HN-detect experiments which have two NH dimensions to enhance peak dispersion in a sequential walk through C', NH and HN, and provide more accurate NH/HN chemical shifts than those that can be obtained from a crowded 1H, 15N-HSQC spectrum. Application of these 4D experiments is demonstrated using BilRI (165 aa), an outer-membrane intrinsically disordered protein from the opportunistic oral pathogen Aggregatibacter actinomycetemcomitans. BilRI amino acid sequence encompasses three very similar repeats with a 13-residue identical stretch in two of them.

中文翻译：

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从Cα或NH的分散体：4D实验用于固有紊乱蛋白的骨架共振分配。

由于构象异质性引起的化学位移分散少，固有无序蛋白的共振分配非常具有挑战性。如果氨基酸序列中存在重复区段，则挑战甚至更大。为了转发固有紊乱蛋白的明确共振分配，我们提出了iHACANCO，HACACON和（HACA）CONCAHA，这是三个Hα检测到的4D实验，其中Cα作为附加维度。此外，我们提出了（HACA）CON（CA）NH和（HACA）N（CA）CONH，这是一种新的4DHα-start，HN检测实验，具有两个NH维数，可在通过C'的顺序步移中增强峰色散， NH和HN，并比从拥挤的1H，15N-HSQC光谱中获得的NH / HN化学位移更准确。使用BilRI（165 aa）演示了这些4D实验的应用，来自机会性口腔病原体集热放线菌的外膜固有紊乱蛋白。BilRI氨基酸序列包含三个非常相似的重复序列，其中两个重复序列具有13个残基。