Heating and temperature gradients of lipid bilayer samples induced by RF irradiation in MAS solid-state NMR experiments
Heating and temperature gradients of lipid bilayer samples induced by RF irradiation in MAS solid-state NMR experiments
复制标题
MAS 固态 NMR 实验中射频辐射引起的脂质双层样品的加热和温度梯度
DOI：
10.1002/mrc.4450
复制
发表时间：
2016-09-01
影响因子：
2
通讯作者：
Yang，Jun
中科院分区：
文献类型：
--
作者：
Wang，Jing;Zhang，Zhengfeng;Yang，Jun
MAS固态NMR是研究天然脂质双层环境中膜蛋白的强大技术。一般来说，MAS NMR实验中的RF辐射会加热并可能破坏昂贵的膜蛋白样品。然而，在实际的MAS NMR实验条件下，脂双层样品的RF加热效应的详细表征仍然缺乏。本文利用水的1H化学位移作为温度定标，系统地研究了MAS NMR实验中三种脂类的水化程度和盐浓度对射频加热的依赖性。在生物MAS NMR实验中使用的实际1H去耦条件下，三种脂质显示出不同的RF加热对水合水平以及作为盐浓度的依赖性，这与脂质的性质密切相关。对于含有200%水合的三种脂质，约10 °C的最大温度升高是相似的，这远低于静态固态NMR实验中的温度升高。观察到由于盐引起的RF加热小于由于水合引起的RF加热，在含有120 mmol l− 1盐的水合样品中，最大温度升高小于4 °C。在RF辐照下，观察到样品上的温度梯度大大增加至20 °C，如水的1H信号的显著加宽所证明的。基于RF加热效应的详细表征，我们证明了RF加热和温度梯度可以通过将脂质双层样品的水合水平从200%降低到30%来显著降低。版权所有© 2016约翰威利父子有限公司.
The MAS solid‐state NMR has been a powerful technique for studying membrane proteins within the native‐like lipid bilayer environment. In general, RF irradiation in MAS NMR experiments can heat and potentially destroy expensive membrane protein samples. However, under practical MAS NMR experimental conditions, detailed characterization of RF heating effect of lipid bilayer samples is still lacking. Herein, using1H chemical shift of water for temperature calibration, we systematically study the dependence of RF heating on hydration levels and salt concentrations of three lipids in MAS NMR experiments. Under practical1H decoupling conditions used in biological MAS NMR experiments, three lipids show different dependence of RF heating on hydration levels as well as salt concentrations, which are closely associated with the properties of lipids. The maximum temperature elevation of about 10 °C is similar for the three lipids containing 200% hydration, which is much lower than that in static solid‐state NMR experiments. The RF heating due to salt is observed to be less than that due to hydration, with a maximum temperature elevation of less than 4 °C in the hydrated samples containing 120 mmol l−1of salt. Upon RF irradiation, the temperature gradient across the sample is observed to be greatly increased up to 20 °C, as demonstrated by the remarkable broadening of1H signal of water. Based on detailed characterization of RF heating effect, we demonstrate that RF heating and temperature gradient can be significantly reduced by decreasing the hydration levels of lipid bilayer samples from 200% to 30%. Copyright © 2016 John Wiley & Sons, Ltd.