Spin-label EPR T1 values using saturation recovery from 2 to 35 GHz
Spin-label EPR T1 values using saturation recovery from 2 to 35 GHz
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DOI：
10.1021/jp036329z
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发表时间：
2004-07-08
影响因子：
3.3
通讯作者：
Froncisz, W
中科院分区：
文献类型：
--
作者：
Hyde, JS;Yin, JJ;Froncisz, W
氮氧自由基自旋探针的电子自旋晶格弛豫时间 T-1 的 EPR 饱和恢复 (SR) 测量已在 2 至 35 GHz 范围内进行。在整个可用频率范围内，小型水溶性自旋探针的 T-1 值随微波频率线性增加。脂质双层中四种常用疏水性探针的 T-1 值也随着频率的增加而增加，但依赖性较弱且复杂。溶解分子氧对弛豫率的贡献与微波频率无关。包含 N-15 的标签的 T-1 值总是比 N-14 标签的 T-1 值稍长。提供了基于频率转换技术的 Q 波段 SR 光谱仪的详细信息。已经找到了一种抑制 SR 实验中自由感应衰变信号的新方法：泵浦和观察频率时间锁定且频率间隔约 1 kHz。样品体积为 30 nl 的新型三环两间隙谐振器用于 Q 波段测量。结论是 Q 波段是 SR 自旋标签血氧测定研究的有利频率。
EPR saturation-recovery (SR) measurements of the electron spin-lattice relaxation time, T-1, of nitroxide-radical spin probes have been made from 2 to 35 GHz. T-1 values of small water-soluble spin probes increase linearly with microwave frequency throughout the full range of available frequencies. T-1 values of four commonly used hydrophobic probes in lipid bilayers also increase with frequency, but the dependence is weaker and complex. Contributions of dissolved molecular oxygen to relaxation rates were independent of microwave frequency. T-1 values of N-15-containing labels are always somewhat longer than for N-14 labels. Details of the Q-band SR spectrometer, which is based on frequency translation technology, are provided. A new way to suppress free induction decay signals in SR experiments has been found: pump and observing frequencies time-locked and separated by about 1 kHz in frequency. A novel three-loop-two-gap resonator with a sample volume of 30 nl was used for the Q-band measurements. It is concluded that Q-band is a favorable frequency for SR spin-label oximetry studies.