LnDOTA-d8 , a versatile chemical-shift thermometer for 2 H solid-state NMR
LnDOTA-d8 , a versatile chemical-shift thermometer for 2 H solid-state NMR
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LnDOTA-d8，一种用于 2 H 固态 NMR 的多功能化学位移温度计
DOI：
10.1002/mrc.5303
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发表时间：
2022
影响因子：
2
通讯作者：
Murata Michio
中科院分区：
文献类型：
--
作者：
Umegawa Yuichi;Shimonishi Takeshi;Tsuchikawa Hiroshi;Murata Michio
2 H固体核磁共振（NMR）是一种在生物物理学领域检查分子迁移率和方向的方法。在对脂质双层膜的研究中，2 H NMR通常用于检测从凝胶相到液晶相的相变，这被观察为光谱形状的变化，并使用四极耦合值来评估脂质烷基链的有序性。由于膜脂的流动性高度依赖于温度，因此精确的温度控制是评估膜物理性质的先决条件。通常，NMR仪器监测可变温度（VT）气体的温度。只有当从线圈或魔角旋转发射的射频（rf）脉冲产生的热量显著低于VT气体的冷却能力时，样品管和VT气体内部的温度才匹配。换句话说，管内的样品温度取决于测量方法。因此，在这项研究中，我们利用顺磁性金属-配体络合物的化学位移的温度依赖性变化。我们设计并合成了一种氘代配体配合物，并评估了其作为2 H固态NMR光谱温度计的温度依赖性。我们选择Tb，Dy，Ho和Er作为顺磁性中心金属。然后，我们测量了每个金属配合物的2 H NMR谱，并证实了2 H化学位移是温度依赖性的。此外，通过使用含Er的温度计分子，我们成功地以0.1°C的精度精确地评估了脂双层中烷基链的链段熔融。
2H solid‐state nuclear magnetic resonance (NMR) is a method for examining the mobility and orientation of molecules in the field of biophysics. In studies on lipid bilayer membranes,2H NMR is often adopted to detect a phase transition from the gel to the liquid‐crystal phase, which is observed as a change in spectral shape, and to evaluate the ordering of lipid alkyl chains using quadrupole coupling values. Because the mobility of membrane lipids is highly temperature dependent, precise temperature control is a prerequisite for evaluating the physical properties of membranes. Generally, NMR instruments monitor the temperature of the variable temperature (VT) gas. The temperature inside the sample tube and the VT gas match only when the heat generated by the radio frequency (rf) pulse emitted from the coil or magic angle spinning is significantly lower than the cooling capacity of the VT gas. In other words, the sample temperature inside the tube depends on the measurement method. Therefore, in this study, we took advantage of temperature‐dependent changes in the chemical shift of a paramagnetic metal–ligand complex. We designed and synthesized a deuterated ligand complex and evaluated its temperature dependence as a thermometer for2H solid‐state NMR spectroscopy. We chose Tb, Dy, Ho, and Er as the paramagnetic central metals. We then measured the2H NMR spectrum of each metal complex and confirmed the2H chemical shift to be temperature dependent. Furthermore, with the use of the thermometer molecule with Er, we succeeded in accurately evaluating the segmental melting of an alkyl chain in lipid bilayers with 0.1°C accuracy.