Residual dipolar couplings (RDCs) provide both structural and dynamical information useful in the characterization of biological macromolecules. While most data come from the interaction of simple pairs of directly bonded spin-1/2 nuclei (1H-15N, 1H-13C, 1H-1H), it is possible to acquire data from interactions among the multiple spins of 13C-labeled methyl groups (1H3-13C). This is especially important because of the advantages that observation of 13C-labeled methyl groups offers in working with very large molecules. Here we consider some of the options for measurement of methyl RDCs in large and often fully protonated proteins and arrive at a pulse sequence that exploits both J-modulation and direct detection of 13C. Its utility is illustrated by application to a fully protonated two domain fragment from the mammalian glycoprotein, Robo1, 13C-methyl-labeled in all valines.

中文翻译：

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通过碳检测测量甲基中残留的偶极偶合。

残留偶极偶合（RDC）提供结构和动力学信息，可用于表征生物大分子。虽然大多数数据来自直接键合的自旋1/2核（1H-15N，1H-13C，1H-1H）的简单对相互作用，但有可能从13C标记的甲基的多次自旋之间的相互作用获取数据组（1H3-13C）。这一点特别重要，因为观察13C标记的甲基在处理非常大的分子时具有优势。在这里，我们考虑了一些用于测量大型且通常具有完全质子化的蛋白质中的甲基RDC的选项，并得出了利用J调制和直接检测13C的脉冲序列。通过将其应用于哺乳动物糖蛋白Robo1，