1 H‐decoupling and Isotopic Labeling for the Measurement of the Longitudinal Relaxation Time of Hyperpolarized 13 C‐Methylenes in Choline Analogs
1 H‐decoupling and Isotopic Labeling for the Measurement of the Longitudinal Relaxation Time of Hyperpolarized 13 C‐Methylenes in Choline Analogs
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1 H-解偶联和同位素标记用于测量胆碱类似物中超极化 13 C-亚甲基的纵向弛豫时间
DOI：
10.1002/ijch.201900016
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发表时间：
2019
影响因子：
3.2
通讯作者：
Katz‐Brull, Rachel
中科院分区：
文献类型：
--
作者：
Uppala, Sivaranjan;Gamliel, Ayelet;Harris, Talia;Sosna, Jacob;Gomori, J. Moshe;Jerschow, Alexej;Katz‐Brull, Rachel
溶液中超极化位点的T1是决定其NMR信号可观察的时间窗口的关键参数。对于邻近质子的13 C位点，1H-去偶已被证明可以提高超极化信号分辨率和SNR。此外，质子的极化转移已经显示出在增加检测灵敏度方面的实用性。然而，1H-去偶联可能导致超极化13 C位点的衰变速率发生变化。在这里，我们测试了这种可能的效果，在这种情况下，质子直接结合到sp3超极化13 C位点（使用[1，2 - 13 C2]胆碱），并且在整个超极化衰变测量中连续应用1H-去偶。我们发现，1H-去偶并没有导致13 C极化衰减时间的任何显着变化，但确实导致了J-耦合的预期崩溃，并产生了更尖锐的信号。这一结果表明，1H-去偶不影响超极化sp3 13 C位点的衰变速率。氘取代方法（使用[1，1，2，2-D4，1 - 13 C]胆碱）显示T1显著延长。计算了所有研究部位的T1上限。
The T1of a hyperpolarized site in solution is a key parameter that determines the time‐window in which its NMR signals are observable. For13C sites adjacent to protons,1H‐decoupling has been shown to increase the hyperpolarized signal resolution and SNR. Additionally, polarization transfer to protons has shown utility in increasing the sensitivity of detection. However,1H‐decoupling could lead to a change in the decay rate of a hyperpolarized13C site. Here we tested this possible effect in a case where the protons are directly bound to an sp3hyperpolarized13C site (using [1,2‐13C2]choline) and1H‐decoupling was applied continuously throughout the hyperpolarized decay measurement. We found that1H‐decoupling did not lead to any significant changes in the13C polarization decay time but did result in the expected collapse of J‐coupling and produced sharper signals. This result suggested that1H‐decoupling did not affect the decay rate of hyperpolarized sp3 13C sites. The deuterium‐substitution approach (using [1,1,2,2‐D4,1‐13C]choline) showed a dramatic prolongation of T1. Upper bounds on the T1of all investigated sites were calculated.