MEASUREMENT OF RELAXATION RATES IN CROWDED NMR-SPECTRA BY SELECTIVE COHERENCE TRANSFER
MEASUREMENT OF RELAXATION RATES IN CROWDED NMR-SPECTRA BY SELECTIVE COHERENCE TRANSFER
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DOI：
10.1021/ja00039a062
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发表时间：
1992-06-17
影响因子：
15
通讯作者：
BODENHAUSEN, G
中科院分区：
文献类型：
--
作者：
BOULAT, B;KONRAT, R;BODENHAUSEN, G
在拥挤的NMR光谱，它示出了如何纵向弛豫速率（实验室帧速率1/T1）可以通过选择性反转恢复的一个选定的网站A，然后通过一个标量耦合J（AX）的磁化选择性转移到另一个网站X，在观察信号之前测量。在自旋锁定（旋转帧速率1/T1-rho）的存在下的弛豫速率可以通过首先选择性地将横向磁化从位置X转移到A，然后选择性地自旋锁定A的磁化，然后可以在部分衰减后观察到。在这两种情况下，转移可以通过双选择性home-hartmann-hahn方法来实现，该方法通过音频调制射频场的边带同时使用站点A和X的横向磁化分量的自旋锁定。如果二维相关（“COSY”）光谱中的A-X交叉峰多重峰不发生重叠，则由新方法产生的一维光谱中不存在模糊性。该技术使得有可能测量精确的自弛豫率rho或rho（t）（所罗门矩阵的对角元素），这对于定量分析实验室或旋转坐标系中的Overhauser效应是重要的。该方法适用于蛋白质牛胰蛋白酶抑制剂（BPTI）和环状十一肽环孢菌素A（CsA）。
In crowded NMR spectra, it is shown how longitudinal relaxation rates (laboratory-frame rates 1/T1) can be measured by selective inversion-recovery of a chosen site A followed by selective transfer of magnetization to another site X through a scalar coupling J(AX), prior to observation of the signal. Relaxation rates in the presence of spin-locking (rotating frame rates 1/T1-rho) can be measured by first transferring transverse magnetization selectively from site X to A, followed by selective spin-locking of the magnetization of A, which can then be observed after partial decay. In both cases, the transfer can be achieved by a doubly-selective homonuclear Hartmann-Hahn method that uses simultaneous spin-locking of the transverse magnetization components of sites A and X by sidebands of an audio-modulated radio-frequency field. Provided the A-X cross-peak multiplet in a two-dimensional correlation (''COSY'') spectrum does not suffer from overlap, there is no ambiguity in the one-dimensional spectra resulting from the novel methods. The techniques make it possible to measure accurate self-relaxation rates-rho or rho(t) (diagonal elements of the Solomon matrices), which are important for a quantitative analysis of Overhauser effects in either laboratory or rotating frames. The methods are applied to the protein bovine pancreatic trypsin inhibitor (BPTI) and to the cyclic undecapeptide cyclosporin A (CsA).