Dynamics of protein side chains is one of the principal determinants of conformational entropy in protein structures and molecular recognition events. We describe NMR experiments that rely on the use of magic‐angle pulses for efficient isolation of degenerate ¹H transitions of the I=3/2 manifold of ¹³CH₃ methyl groups, and serve as ‘building blocks’ for the measurement of transverse spin relaxation rates of the fast‐ and slow‐relaxing ¹H transitions – the primary quantitative reporters of methyl axis dynamics in selectively {¹³CH₃}‐methyl‐labelled, highly deuterated proteins. The magic‐angle‐pulse driven experiments are technically simpler and, in the absence of relaxation, predicted to be 2.3‐fold more sensitive than previously developed analogous schemes. Validation of the methodology on a sample of {¹³CH₃}‐labeled ubiquitin demonstrates quantitative agreement between order parameters of methyl three‐fold symmetry axis obtained with magic‐angle‐pulse driven experiments and other established NMR techniques, paving the way for studies of methyl axis dynamics in human DNAJB6b chaperone, a protein that undergoes exchange with high‐molecular‐weight oligomeric species.

中文翻译：

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魔角脉冲驱动的蛋白质甲基团中简并 1 H 跃迁的分离：在甲基轴动力学研究中的应用。

蛋白质侧链的动力学是蛋白质结构和分子识别事件中构象熵的主要决定因素之一。我们描述了依靠使用魔角脉冲来有效隔离¹³ CH _3甲基的I = 3/2 歧管的简并¹ H 跃迁的NMR 实验，并用作测量横向自旋的“构件”快慢弛豫¹ H 跃迁的弛豫率——选择性 { ¹³ CH ₃中甲基轴动力学的主要定量报告者}-甲基标记的高度氘化蛋白质。魔角脉冲驱动实验在技术上更简单，并且在没有松弛的情况下，预计比以前开发的类似方案灵敏 2.3 倍。^{该方法在 { 13} CH ₃ } 标记的泛素样品上的验证表明，通过魔角脉冲驱动实验和其他已建立的 NMR 技术获得的甲基三重对称轴的有序参数之间存在定量一致性，为研究人类 DNAJB6b 伴侣蛋白中的甲基轴动力学，这是一种与高分子量寡聚物种进行交换的蛋白质。