On the accurate measurement of amide one-bond 15N-1H couplings in proteins:: Effects of cross-correlated relaxation, selective pulses and dynamic frequency shifts
On the accurate measurement of amide one-bond 15N-1H couplings in proteins:: Effects of cross-correlated relaxation, selective pulses and dynamic frequency shifts
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DOI：
10.1016/j.jmr.2006.08.003
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发表时间：
2006-11-01
影响因子：
2.2
通讯作者：
Tjandra, Nico
中科院分区：
文献类型：
--
作者：
de Alba, Eva;Tjandra, Nico
通过监测NMR信号强度调制，用定量J方法测量了N-15-和[N-15，H-2]-同位素富集的泛素的酰胺单键N-15-H-1标量耦合。非氘代蛋白质的标量耦合平均类似于比氘代泛素的值大0.6 Hz。该偏差是实验再现性产生的误差的30倍。重聚焦偶极/偶极交叉相关弛豫将差异减小到类似于0.1 Hz，这表明它可能源于弛豫干扰。或者，在不同磁场下获得的J值的减法大大降低了弛豫效应。相比之下，动态频移的主要贡献（1）J（15 N-H-1）来自N-15化学屏蔽各向异性/NH偶极互相关，并没有消除重新聚焦自旋演化在这种相互作用。此外，（1）J（N-15-H-1）值在两个磁场下的平均差异与理论预期的动态频移差异非常一致。爱思唯尔公司出版
Amide one-bond N-15-H-1 scalar couplings of N-15- and [N-15,H-2]-isotopically enriched ubiquitin have been measured with the Quantitative J approach by monitoring NMR signal intensity modulation. Scalar couplings of the non-deuterated protein are in average similar to 0.6 Hz larger than values of deuterated ubiquitin. This deviation is 30 times the error derived from experiment reproducibility. Refocusing dipole/dipole cross-correlated relaxation decreases the discrepancy to similar to 0.1 Hz, suggesting that it likely originates from relaxation interference. Alternatively, the subtraction of J values obtained at different magnetic fields largely reduces the relaxation effects. In contrast, the dynamic frequency shift whose main contribution to (1)J(15N-H-1) arises from N-15 chemical shielding anisotropy/NH dipole cross-correlation, is not eliminated by refocusing spin evolution under this interaction. Furthermore, the average difference of (1)J(N-15-H-1) values at two magnetic fields closely agrees with the theoretical expected difference in the dynamic frequency shift. Published by Elsevier Inc.