HIGH-FIELD DNP AND EPR IN BIOLOGICAL SYSTEMS

该提案概述了与高风险相关的三个领域的研究。 频率动态核极化和电子自旋共振 (ESR)电子核双共振（ENDOR） (1)将开发高频CW和脉冲DNP方法， 用于增强模型系统的MAS NMR谱中的信号强度 和大蛋白质。实验将使用140 GHz回旋管 振荡器，其建设现已完成，并将适用于 涉及含有原位顺磁中心的蛋白质，例如酪氨酰 自由基，并与顺磁性蛋白质分散在 溶剂后(2)140 GHz脉冲ESR实验将用于研究 电子自旋的频率、浓度和温度依赖性 DNP实验模型系统中的晶格弛豫（T1 e）， proteins.这些数据对于优化 偏振增强，在确定蛋白质的结构 含有自由基和顺磁中心， 有趣.（3）140 GHz CW ESR和ENDOR研究计划用于 (a)一系列的模型化合物需要研究与脉冲和 CW DNP实验;（B）氧化还原蛋白质的大类和扩展类 含有酪氨酰自由基--核糖核苷酸还原酶、细胞色素-c 过氧化物酶，半乳糖氧化酶等--我们计划在那里确定 高场光谱用于识别自由基种类的实用性 与抑制剂反应形成的自由基结构;（c）Mn 2 + 含有蛋白质，如ras-p2 l，我们将使用光谱 在高场发生的窄化，以检测线宽贡献 来自17 O-标记的配体，和（d）光合反应中心，其中 我们将从单个g-张量确定分子取向， 晶体研究

This proposal outlines research in three areas associated with high frequency dynamic nuclear polarization (DNP) and electron spin resonance (ESR) and electron nuclear double resonance (ENDOR). (1) High frequency CW and pulsed DNP methods will be developed and employed to enhance signal strengths in MAS NMR spectra of model systems and large proteins. The experiments will utilize a 140 GHz gyrotron oscillator, whose construction is now complete, and will be applicable to proteins containing in-situ paramagnetic centers, such as tyrosyl radicals, and to diamagnetic proteins with paramagnetic dispersed in the solvent. (2) 140 GHz pulsed ESR experiments will be used to study the frequency, concentration and temperature dependence of the electron spin lattice relaxation (T1e) in model systems for DNP experiments and in proteins. The data are useful for optimizing the rate and magnitude of polarization enhancements, in determining structures of proteins containing free radicals and paramagnetic centers, and are inherently interesting. (3)140 GHz CW ESR and ENDOR investigations are planned for (a) a series of model compounds necessary to be studied with pulsed and CW DNP experiments; (b) a large and expanding class of redox proteins containing tyrosyl radicals -- ribonucleotide reductase, cytochrome-c peroxidase, galactose oxidase, etc. -- where we plan to determine the utility of high field spectra for identifying radical species and the structure of radicals formed on reaction with inhibitors; (c) Mn2+ containing proteins, such as ras-p2l, where we will employ the spectral narrowing which occurs at high field to detect linewidth contributions from 17O-labeled ligands, and (d) photosynthetic reaction centers, where we will determine the molecular orientation of g-tensors from single crystal studies.