TOTAPOL: A biradical polarizing agent for dynamic nuclear polarization experiments in aqueous media
TOTAPOL: A biradical polarizing agent for dynamic nuclear polarization experiments in aqueous media
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DOI：
10.1021/ja061284b
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发表时间：
2006-09-06
影响因子：
15
通讯作者：
Griffin, Robert G.
中科院分区：
文献类型：
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作者：
Song, Changsik;Hu, Kan-Nian;Griffin, Robert G.
在以前的一篇文章中，我们描述了双自由基的使用，在这种情况下，两个由可变长度的乙二醇链连接的TEMPO分子作为偏振剂用于微波驱动的动态核极化(DNP)实验。使用双自由基来代替单体顺磁中心，例如TEMPO，可以产生大约4倍大的增强(在5T和90K时，ε类似于175)，同时，极化剂的浓度是小4倍(10 mm电子自旋)，减少剩余电子核偶极展宽。本文报道了一种改进的极化剂1-(TEMPO-4-氧基)-3(TEMPO-4-氨基)丙烷-2-醇(TOTAPOL)的合成及EPR和DNP/核磁共振表征。在相同的实验条件下，使用2.5 mm魔角转子，这种新的双自由基能在较低浓度(6 mm电子自旋)下产生更大的增强(epsilon类似于290)，并具有额外的重要性质，即它与水介质中的实验兼容，包括蛋白质和核酸研究中常用的盐溶液。
In a previous publication, we described the use of biradicals, in that case two TEMPO molecules tethered by an ethylene glycol chain of variable length, as polarizing agents for microwave driven dynamic nuclear polarization (DNP) experiments. The use of biradicals in place of monomeric paramagnetic centers such as TEMPO yields enhancements that are a factor of approximately 4 larger (epsilon similar to 175 at 5 T and 90 K) and concurrently the concentration of the polarizing agent is a factor of 4 smaller (10 mM electron spins), reducing the residual electron nuclear dipole broadening. In this paper we describe the synthesis and characterization by EPR and DNP/NMR of an improved polarizing agent 1-(TEMPO-4-oxy)-3(TEMPO-4- amino)propan-2-ol (TOTAPOL). Under the same experimental conditions and using 2.5 mm magic angle rotors, this new biradical yields larger enhancements (epsilon similar to 290) at lower concentrations (6 mM electron spins) and has the additional important property that it is compatible with experiments in aqueous media, including salt solutions commonly used in the study of proteins and nucleic acids.