USING NITROXIDE SPIN LABELS - HOW TO OBTAIN T(1E) FROM CONTINUOUS WAVE ELECTRON-PARAMAGNETIC RESONANCE-SPECTRA AT ALL ROTATIONAL RATES
USING NITROXIDE SPIN LABELS - HOW TO OBTAIN T(1E) FROM CONTINUOUS WAVE ELECTRON-PARAMAGNETIC RESONANCE-SPECTRA AT ALL ROTATIONAL RATES
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DOI：
10.1016/s0006-3495(93)81418-8
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发表时间：
1993-03-01
影响因子：
3.4
通讯作者：
ROBINSON, BH
中科院分区：
文献类型：
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作者：
HAAS, DA;MAILER, C;ROBINSON, BH
从历史上看，连续波电子顺磁共振（CW-EPR）渐进饱和法已被用来获得信息的自旋晶格弛豫时间（T1 e）和那些过程，如运动和自旋交换，发生在一个竞争的时间尺度。例如，已经通过这种方法获得了关于蛋白质和核酸的局部动力学和溶剂可及性的定性信息。然而，从CW-EPR光谱T1 e的定量估计已受挫的T1 e（和T2 e）在慢动作制度中的作用缺乏了解。本文用理论模拟方法研究了在高功率下慢运动区的CW-EPR谱线，以检验饱和技术是否能定量估计自旋-晶格弛豫速率。提出了一种从功率-饱和翻转曲线中提取正确的T_1e的方法，而不管不均匀加宽的量或分子重新取向的速率。从10到200 ns的运动相关时间的范围应该是最佳的提取定量估计T1 e值的自旋标记的生物分子。渐进饱和翻转曲线方法应该在需要分子相互作用和溶剂暴露以及分子重取向率信息的生物物理学领域得到广泛应用。
Historically, the continuous wave electron paramagnetic resonance (CW-EPR) progressive saturation method has been used to obtain information on the spin-lattice relaxation time (T1e) and those processes, such as motion and spin exchange, that occur on a competitive timescale. For example, qualitative information on local dynamics and solvent accessibility of proteins and nucleic acids has been obtained by this method. However, making quantitative estimates of T1e from CW-EPR spectra have been frustrated by a lack of understanding of the role of T1e (and T2e) in the slow-motion regime. Theoretical simulation of the CW-EPR lineshapes in the slow-motion region under increasing power levels has been used in this work to test whether the saturation technique can produce quantitative estimates of the spin-lattice relaxation rates, A method is presented by which the correct T1e may be extracted from an analysis of the power-saturation rollover curve, regardless of the amount of inhomogeneous broadening or the rates of molecular reorientation. The range of motional correlation times from 10 to 200 ns should be optimal for extracting quantitative estimates of T1e values in spin-labeled biomolecules. The progressive-saturation rollover curve method should find wide application in those areas of biophysics where information on molecular interactions and solvent exposure as well as molecular reorientation rates are desired.