Low-conductivity buffers for high-sensitivity NMR measurements
Low-conductivity buffers for high-sensitivity NMR measurements
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DOI：
10.1021/ja026121b
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发表时间：
2002-10-09
影响因子：
15
通讯作者：
Dötsch, V
中科院分区：
文献类型：
--
作者：
Kelly, AE;Ou, HD;Dötsch, V
导电样品产生的电噪声会大大降低核磁共振（NMR）探头的灵敏度，特别是最近推出的低温探头。特别是，生物大分子样品通常含有盐以保持pH恒定并防止聚集，灵敏度可能会显着降低。到目前为止，这种依赖性迫使研究人员尽量减少样品中的盐浓度。在这里，我们证明了决定性因素不是盐浓度本身，而是电导率，它是溶液中离子浓度和迁移率的函数。我们表明，通过选择具有低离子迁移率的缓冲液，与使用相同浓度的标准NMR缓冲液（如磷酸盐）进行的相同测量相比，样品电导率可以显著降低，灵敏度大幅提高，我们进一步表明，一种缓冲液比另一种缓冲液的最高灵敏度增益等于它们的离子迁移率之比的平方根，并描述了一种简单的方法来评估缓冲液对灵敏度的影响。
The sensitivity of nuclear magnetic resonance (NMR) probes, especially the recently introduced cryogenic probes, can be substantially reduced by the electrical noise generated by conductive samples. In particular, samples of biological macromolecules, which usually contain salts to keep the pH constant and to prevent aggregation, can experience a significant reduction in sensitivity. So far this dependence has forced researchers to minimize the salt concentrations in their samples. Here we demonstrate that the decisive factor is not the salt concentration itself but the conductivity which is a function of both the concentration and the mobility of the ions in solution. We show that by choosing buffers with low ionic mobility, the sample conductivity can be dramatically reduced and the sensitivity substantially enhanced compared to the same measurement with an equal concentration of a standard NMR buffer such as phosphate, We further show that the highest sensitivity gain of one buffer over another buffer is equal to the square root of the ratio of their ion mobilities and describe a simple method to evaluate the effect of a certain buffer on the sensitivity.