HIGH-FIELD DNP AND EPR IN BIOLOGICAL SYSTEMS

生物系统中的高场 DNP 和 EPR

• 批准号: 2179308
• 负责人: ROBERT Guy GRIFFIN
• 金额: $ 34.13万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-04-01 至 1996-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2179308
• 关键词: bacteriorhodopsins; electron spin resonance spectroscopy; free radicals; manganese; method development; nuclear magnetic resonance spectroscopy; oncogenes; optical polarization; photosynthetic reaction centers; protein structure; structural biology; travel; tyrosine

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.

这项提案概述了与HIGH相关的三个领域的研究 频率动态核极化(DNP)与电子自旋共振 电子自旋共振(ESR)和电子核双共振(Endor)。 (1)发展高频连续波和脉冲DNP方法， 用于增强模型体系MAS核磁共振谱中的信号强度 和大型蛋白质。这些实验将使用140 GHz回旋管 振荡器，其构造现已完成，将适用于 到含有原位顺磁中心的蛋白质，如酪氨酸 自由基，以及顺磁分散在分子中的抗磁性蛋白质 溶剂型。(2)140 GHz脉冲ESR实验将用于研究 电子自旋的频率、浓度和温度关系 DNP实验和In模型体系中的晶格驰豫(T1e) 蛋白质。这些数据对优化地震的速度和大小是有用的 极化增强在确定蛋白质结构中的作用 含有自由基和顺磁中心，并且本身就是 有意思的。(3)计划进行140 GHz连续波ESR和Endor调查 (A)一系列需要用脉冲和电子显微镜研究的模型化合物 CW DNP实验；(B)一大类不断扩大的氧化还原蛋白质 含有酪氨酸基的核糖核苷酸还原酶，细胞色素-c 过氧化物酶、半乳糖氧化酶等--我们计划在这些地方确定 高场光谱在鉴定自由基物种上的应用 与抑制剂反应形成的自由基的结构；(C)Mn2+ 包含蛋白质，如ras-p21，我们将在其中使用光谱 在高场发生的窄化，以检测线宽贡献 和(D)光合作用反应中心，其中 我们将确定g张量的分子取向，从单个 水晶研究。