Arginine side chains play critical roles in many protein-ligand interactions and enzyme catalysis. Unambiguous resonance assignment is a prerequisite for the nuclear magnetic resonance (NMR) spectroscopy studies of arginine side chains dynamics and hydrogen exchange properties from which one can expect to elucidate in more detail the roles of arginine residues in protein structure and function. Here we present a new mass spectrometry (MS)-based method for assigning the side-chain resonances of arginine residues in 2D 1H-15N NMR spectra. The method requires no additional isotopic labeling, and relies on knowledge of the amino acid sequence, the modification of the guanidino groups and liquid chromatography-mass spectrometry rather than the protein's structure or properties. Correlating the modification rates can connect cross-peak positions from NMR data with MS data to support resonances assignments. In the present work, we have extended our original application to natural abundance human ubiquitin to provide ε-NH assessments of three arginine for this well-studied protein.

中文翻译：

---

质谱辅助天然丰度蛋白中NMR共振的精氨酸侧链分配。

精氨酸侧链在许多蛋白质-配体相互作用和酶催化中起关键作用。明确的共振分配是精氨酸侧链动力学和氢交换性质的核磁共振（NMR）光谱研究的先决条件，从中人们可以期望更详细地阐明精氨酸残基在蛋白质结构和功能中的作用。在这里，我们提出了一种基于质谱（MS）的新方法，用于分配2D 1H-15N NMR光谱中精氨酸残基的侧链共振。该方法不需要额外的同位素标记，并且依赖于氨基酸序列的知识，胍基基团的修饰和液相色谱-质谱法，而不是蛋白质的结构或性质。关联修饰率可以将NMR数据与MS数据的跨峰位置联系起来，以支持共振分配。在目前的工作中，我们已经将我们的原始应用扩展到自然丰度的人类泛素，以为这种经过充分研究的蛋白质提供三个精氨酸的ε-NH评估。