MAPPING OF THE SPECTRAL DENSITIES OF N-H BOND MOTIONS IN EGLIN-C USING HETERONUCLEAR RELAXATION EXPERIMENTS
MAPPING OF THE SPECTRAL DENSITIES OF N-H BOND MOTIONS IN EGLIN-C USING HETERONUCLEAR RELAXATION EXPERIMENTS
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DOI：
10.1021/bi00151a027
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发表时间：
1992-09-15
期刊：
影响因子：
2.9
通讯作者：
WAGNER, G
中科院分区：
文献类型：
--
作者：
PENG, JW;WAGNER, G
一种新的策略是用于研究基于NMR弛豫参数测量的蛋白质的内部运动。该策略产生N-H键矢量的所谓的谱密度函数J（ω）的值。谱密度函数与这些NH键矢量的旋转（整体和内部）运动中包含的频率分布有关。在这种方法中，不需要关于动态的先验模型假设。该方法包括测量6个弛豫参数，包括N-15纵向弛豫速率，同相和反相相干的横向弛豫速率，杂原子H-1-N-15双自旋序的弛豫速率，杂原子H-1-N-15核的Overhauser效应，以及酰胺质子的纵向弛豫速率。在五个频率0、ω（N）、ω（H）+ ω（N）、ω（H）和ω（H）-ω（N）处的谱密度函数的值是使用先前导出的分析关系从弛豫参数确定的[Peng和瓦格纳（1992）J. Magn. Reson. 98，308-332]。在这里，该方法适用于表征的N-15-富集蛋白酶抑制剂eglin C，70个残基的蛋白质的骨架动力学。J（0）和J（ω（N）= 50 MHz）的值随氨基酸序列而显著变化，而在较高频率J（450 MHz）、J（500 MHz）和J（550 MHz）处的谱密度通常小得多，并且不显示随序列的显著变化。J（Ω）值的集体行为表明蛋白酶结合环残基和前八个N-末端残基的内部运动更大。这些区域中的附加内部运动在低于450 MHz的速率范围内。J（ω）的值也进行了比较，与根均方差（均方根偏差）的骨架原子中获得的NMR结构测定。J（0）和J（ω（N））的低值与高rmsd相关。在较高频率J（450 MHz）、A500 MHz）和J（550 MHz）处的谱密度较小，并且与均方根差没有相关性。与通过将实验数据拟合到Lipari和Szabo形式主义的函数依赖性而获得的谱密度函数的比较[Lipari & Szabo（1982 a）J. Am. 104，4546-4559]制备。
A new strategy is used for studying the internal motions of proteins based on measurements of NMR relaxation parameters. The strategy yields values of the so-called spectral density functions J(omega) for N-H bond vectors. The spectral density functions are related to the distribution of frequencies contained in the rotational (overall and internal) motions of these NH bond vectors. No a priori model assumptions about the dynamics are required in this approach. The method involves measurements of six relaxation parameters consisting of N-15 longitudinal relaxation rates, transverse relaxation rates of in-phase and antiphase coherence, the relaxation rates of heteronuclear H-1-N-15 two-spin order, the heteronuclear H-1-N-15 nuclear Overhauser effects, and longitudinal relaxation rates of the amide protons. The values of the spectral density functions at the five frequencies 0, omega(N), omega(H) + omega(N), omega(H), and omega(H) - omega(N) are determined from the relaxation parameters using analytical relations derived previously [Peng & Wagner (1992) J. Magn. Reson. 98, 308-332]. Here, the method is applied to characterize the backbone dynamics of the N-15-enriched proteinase inhibitor eglin c, a protein of 70 residues. The values for J(0) and J(omega(N) = 50 MHz) vary significantly with the amino acid sequence, whereas the spectral densities at higher frequencies, J(450 MHz), J(500 MHz), and J(550 MHz), are typically much smaller and show no significant variation with the sequence. The collective behavior of the J(omega) values indicate greater internal motion for the proteinase binding loop residues and the first eight N-terminal residues. The additional internal motion in these regions is in the rate range below 450 MHz. The values of J(omega) are also compared with root mean square deviations (rmsds) of backbone atoms as obtained in NMR structure determinations. Low values of J(0) and J(omega(N)) are correlated with high rmsds. Spectral densities at higher frequencies, J(450 MHz), A500 MHz), and J(550 MHz), are small and show no correlation with rmsds. A comparison with the spectral density functions obtained by fitting the experimental data to the functional dependence of the Lipari and Szabo formalism [Lipari & Szabo (1982a) J. Am. Chem. Soc. 104, 4546-4559] is made.