FAST INTERNAL MAIN-CHAIN DYNAMICS OF HUMAN UBIQUITIN
FAST INTERNAL MAIN-CHAIN DYNAMICS OF HUMAN UBIQUITIN
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DOI：
10.1021/bi00129a013
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发表时间：
1992-04-14
期刊：
影响因子：
2.9
通讯作者：
WAND, AJ
中科院分区：
文献类型：
--
作者：
SCHNEIDER, DM;DELLWO, MJ;WAND, AJ
通过对主链酰胺氮的N-15驰豫过程的分析，研究了人泛素的快速内动力学。用异核多量子光谱对酰胺N-15的共振峰进行了归属。用二维谱测定了蛋白质中67个酰胺N-15位的自旋晶格驰豫时间在60.8 MHz和30.4 MHz，以及稳态核Overhaser效应在60.8 MHz。这些数据已经根据Lipari和Szabo的无模型处理进行了分析[Lipari，G.，&Szabo，A.(1982)J.Am化学。SoC。104、4546-4559]。蛋白质的全球运动是各向同性的，相关时间为4.1 ns rad-1。主链酰胺N-H载体在蛋白质球状区的广义有序参数(S2)在0.5-0.95之间。二级结构与广义有序参数之间没有明显的相关性。然而，在给定的N-H矢量的广义有序参数的大小与酰胺氢或其肽键相关的羰基的氢键的存在之间有很强的相关性。在化学位移张量宽度为160ppm的情况下，参与一个或多个氢键连接到主链的多肽键的N-H矢量的平均广义有序参数为0.80(SD 0.06)，而那些与主链没有氢键作用的多肽键的酰胺NH的平均有序参数为0.69(SD 0.06)。C末端的最后四个残基显示出S2值在0.13到0.63之间的模式，这与围绕phi和psi旋转轴的有限扩散一致，这在残基72处突然终止。这些数据表明，分子堆积相互作用在亚纳秒时间尺度上对内部运动提供了主要的限制，氢键相互作用对主链高频动力学提供了显着但更为适度的衰减。
The fast internal dynamics of human ubiquitin have been studied by the analysis of N-15 relaxation of backbone amide nitrogens. The amide N-15 resonances have been assigned by use of heteronuclear multiple-quantum spectroscopy. Spin lattice relaxation times at 60.8 and 30.4 MHz and the steady-state nuclear Overhauser effect at 60.8 MHz have been determined for 67 amide N-15 sites in the protein using two-dimensional spectroscopy. These data have been analyzed in terms of the model free treatment of Lipari and Szabo [Lipari, G., & Szabo, A. (1982) J. Am. Chem. Soc. 104, 4546-4559]. The global motion of the protein is shown to be isotropic and is characterized by a correlation time of 4.1 ns rad-1. The generalized order parameters (S2) of backbone amide N-H vectors in the globular region of the protein range from 0.5 to 0.95. No apparent correlation between secondary structure and generalized order parameters is observed. There is, however, a strong correlation between the magnitude of the generalized order parameters of a given N-H vector and the presence of hydrogen bonding of the amide hydrogen or its peptide bond associated carbonyl. Using a chemical shift tensor breadth of 160 ppm, the N-H vectors of peptide linkages participating in one or more hydrogen bonds to the main chain show an average generalized order parameter of 0.80 (SD 0.06), while those amide NH of peptide linkages free of hydrogen-bonding interactions with the main chain show an average order parameter of 0.69 (SD 0.06). The last four residues of the C-terminus display a pattern of S2 values ranging from 0.13 to 0.63 consistent with restricted diffusion about phi and psi-rotation axes which is abruptly terminated at residue 72. These data suggest that molecular packing interactions provide the dominant restriction to internal motion on the subnanosecond time scale and that hydrogen-bonding interactions provide a significant but more modest damping of main-chain high-frequency dynamics.