Mori S, Berg J M, van Zijl P C
Department of Biophysics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
J Biomol NMR. 1996 Jan;7(1):77-82. doi: 10.1007/BF00190459.
A technique for separating intramolecular NOE and solvent-proton exchange peaks in exchange spectroscopy is demonstrated. This method utilizes the large differences in relaxation and coupling properties of water and macromolecules to separate the two effects. The spin-echo filter consists of a water-frequency selective 90 degrees pulse followed by a spin-echo sequence. If the echo time is sufficiently long, protein resonances (e.g. C alpha H protons) excited by the selective pulse are removed due to their much shorter T2 values and J-coupling evolution. By combining the filter with exchange spectroscopy (EXSY) or water exchange (WEX) filter experiments, exchange peaks can be selectively observed. In this paper the filter is combined with a modified version of the WEX filter (WEX II filter) with 1D and 2D detection and applied to a zinc finger peptide and to staphylococcal nuclease, allowing estimation of the contribution of intramolecular NOEs to the exchange spectra.
本文展示了一种在交换光谱中分离分子内核Overhauser效应（NOE）和溶剂-质子交换峰的技术。该方法利用水和大分子在弛豫和耦合特性上的巨大差异来分离这两种效应。自旋回波滤波器由一个水频率选择性90度脉冲和随后的自旋回波序列组成。如果回波时间足够长，由选择性脉冲激发的蛋白质共振（如CαH质子）会因其短得多的T2值和J耦合演化而被去除。通过将该滤波器与交换光谱（EXSY）或水交换（WEX）滤波器实验相结合，可以选择性地观察到交换峰。在本文中，该滤波器与具有一维和二维检测的改进版WEX滤波器（WEX II滤波器）相结合，并应用于锌指肽和葡萄球菌核酸酶，从而能够估计分子内NOE对交换光谱的贡献。
