Proton-observed carbon-edited NMR spectroscopy in strongly coupled second-order spin systems
Proton-observed carbon-edited NMR spectroscopy in strongly coupled second-order spin systems
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DOI：
10.1002/mrm.20764
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发表时间：
2006-02-01
影响因子：
3.3
通讯作者：
Ugurbil, K
中科院分区：
文献类型：
--
作者：
Henry, PG;Marjanska, M;Ugurbil, K
质子观察碳编辑（POCE）NMR光谱通常用于测量C-13标记，与直接C-13 NMR光谱相比具有更高的灵敏度，但牺牲了光谱分辨率。对于弱耦合的一阶自旋系统，POCE光谱中特定质子化学位移处的多重峰信号直接反映了附着于该质子的碳的13 C富集。本研究表明，这是不一定的情况下，强耦合的二阶自旋系统。在这种情况下，甚至在对应于与C-12结合的质子的化学位移处，也可以在POCE光谱中检测到NMR信号。理论上证明了这种效果与密度矩阵计算和模拟，并与实测POCE光谱[3-C-13]谷氨酸。
Proton-observed carbon-edited (POCE) NMR spectroscopy is commonly used to measure C-13 labeling with higher sensitivity compared to direct C-13 NMR spectroscopy, at the expense of spectral resolution. For weakly coupled first-order spin systems, the multiplet signal at a specific proton chemical shift in POCE spectra directly reflects 13 C enrichment of the carbon attached to this proton. The present study demonstrates that this is not necessarily the case for strongly coupled second-order spin systems. In such cases NMR signals can be detected in the POCE spectra even at chemical shifts corresponding to protons bound to C-12. This effect is demonstrated theoretically with density matrix calculations and simulations, and experimentally with measured POCE spectra of [3-C-13]glutamate.