ELECTRON SPIN RELAXATION OF NITROXIDES

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 了解电子自旋弛豫对于预测可行性和优化血氧计、活体EPR以及通过弛豫增强和脉冲偶极光谱(DQC和DER)进行距离测量的实验是关键。对于电子自旋弛豫的频率依赖性，目前还没有与现有实验数据相吻合的理论。除了X波段以外，还缺乏可以与理论进行比较的实验数据。由于氮氧基的广泛使用，以及各种同位素取代的氮氧基的可用性，它们被选为本松弛过程的研究对象。本项目研究了两种运动模式(A)活体光谱中典型的快速翻滚和(B)在低温下用于脉冲偶极光谱的固定化样品中弛豫的频率依赖性。伊顿实验室的脉冲能力从250 MHz到34 GHz。ACERT提供9、17、35和95 GHz的高功率脉冲以及170和240 GHz的连续波。Eatons有一组具有[^15]N、[^14]N、[^2]H和[^1]H选择性标记的氮氧基化合物。Acert和DU的其他项目提供了用于脉冲偶极光谱的自旋标记多肽和样品。

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.