ELECTRON SPIN RELAXATION OF NITROXIDES

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 了解电子自旋弛豫是预测可行性和优化血氧测定实验、体内EPR以及通过弛豫增强和脉冲偶极光谱（DQC和DEER）进行距离测量的关键。目前还没有一个理论能解释电子自旋弛豫与频率的关系，与现有的实验数据相吻合。 除X波段外，也缺乏实验数据来与理论进行比较。 由于硝酰基自由基的广泛使用，以及各种同位素取代的硝酰基的可用性，它们被选择用于弛豫过程的研究。 该项目研究了两种运动状态下弛豫的频率依赖性（a）快速翻滚，这是典型的体内光谱学和（B）固定样品在低温下用于脉冲偶极光谱学。 伊顿实验室具有250 MHz至34 GHz的脉冲能力。 ACERT提供9、17、35和95 GHz的高功率脉冲和170和240 GHz的CW。 伊顿有一组硝酰基化合物，具有[^15]N、[^14]N、[^2]H和[^1]H选择性标记。 用于脉冲偶极光谱的自旋标记肽和样品可从ACERT和DU的其他项目获得。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Understanding of electron spin relaxation is key to predicting feasibility, and optimizing experiments for oximetry, in vivo EPR, and distance measurements by relaxation enhancement and pulsed dipolar spectroscopy (DQC and DEER). There is no theory of the frequency dependence of electron spin relaxation that fits available experimental data. There is also a scarcity of experimental data other than at X-band with which to compare theory. Because of the wide-spread use of nitroxyl radicals, and the availability of various isotopically-substituted nitroxyls, they are selected for this study of relaxation processes. This project investigates the frequency dependence of relaxation in two motional regimes (a) rapid tumbling as is typical of in vivo spectroscopy and (b) immobilized samples at cryogenic temperatures as are used for pulsed dipolar spectroscopy. The Eaton lab has pulse capability from 250 MHz to 34 GHz. ACERT offers 9, 17, 35 and 95 GHz with high power pulses and CW at 170 and 240 GHz. The Eatons have a set of nitroxyl compounds with [^15]N, [^14]N, [^2]H, and [^1]H selective labeling. Spin-labeled peptides and samples for pulsed dipolar spectroscopy are available from other projects at ACERT and DU.