Electron Paramagnetic Resonance Spectrometer

描述（由申请人提供）：本申请的目的是要求布鲁克BioSpin公司Elexsys E560连续波电子顺磁共振（EPR）光谱仪，具有10“电磁铁/12千瓦电源，将在X波段（9-10 GHz）和q波段（34 GHz）微波频率下工作，并包括X和q波段的电子核双共振（ENDOR， TRIPLE）附件。还需要在液氦和液氮温度下操作的低温恒温器，以适应顺磁体的不同弛豫特性，以及用于单晶研究的角计。新仪器将取代老化的EPR光谱仪系统。用户组包括PI，一位经验丰富的EPR光谱专家，以及其他三个主要用户和两个次要用户。该仪器将支持美国国立卫生研究院资助的四个用户的研究（5个R01拨款），美国国立卫生研究院资助的一个用户的未决研究，以及另一个用户的初步研究。建议的环境保护报告/ENDOR项目包括：(a)确定辅酶b12依赖酶中电子缺陷自由基介导催化的分子机制；(b)结合穆斯堡尔光谱研究铁硫簇在生物素合成酶、丙酮酸-甲酸裂解酶激活酶和铁氧还蛋白：硫氧还蛋白还原酶中出现的新生物功能；(c)甲苯单加氧酶生物转化芳烃的机制。通过结合蛋白质x射线晶体学检查单晶中的金属位点结构，(d)黄酮类酶的结构和功能，(e)确定二价金属在淀粉样蛋白形成中纤维形成机制中的作用，以及(f)表征自由基介导的DNA链断裂和新型有机金属配合物修饰组蛋白的机制。在q波段操作是合理的，因为需要提高EPR和ENDOR光谱的分辨率，双X和q波段操作对于多频率方法的成功至关重要，以约束光谱模拟分析。请求的EPR光谱仪支持的项目涵盖广泛的公认的生物自由基反应性的研究，从酶的“程序化”基本自由基，到自由基和金属的有害影响，再到使用自由基反应性作为治疗工具。因此，预计EPR光谱仪将对生物医学产生持续的高影响。

DESCRIPTION (provided by applicant): The objective of this application is to request a Bruker BioSpin Corporation Elexsys E560 continuous-wave electron paramagnetic resonance (EPR) spectrometer with 10" electromagnet/12 kW power supply that will operate at X-band (9-10 GHz) and Q-band (34 GHz) microwave frequencies, and include the electron-nuclear double resonance (ENDOR, TRIPLE) accessories for X- and Q-band. Also requested are cryostats for operation at liquid helium and nitrogen temperature, to adjust to the different relaxation properties of the paramagnets, and a goniometer for single crystal studies. The new instrument would replace an aging EPR spectrometer system. The user group includes the PI, an experienced EPR spectroscopist, and three other Major Users and two Minor Users. The instrument will support the NIH-funded research of four users (5 R01 grants), the pending NIH-funded research of one user, and the preliminary studies of another. The proposed EPR/ENDOR projects include the following: (a) determination of the molecular mechanism of electrondeficient radical-mediated catalysis in coenzyme B12-dependent enzymes, (b) investigation of the emergent novel biological functions of iron-sulfur clusters in biotin synthase, pyruvate-formate lyase activating enzyme, and ferredoxin:thioredoxin reductase, in combination with Mossbauer spectroscopy, (c) the mechanism of biotransformation of aromatic hydrocarbons by toluene monooxygenases, by examining metal site structure in single crystals in combination with protein X-ray crystallography, (d) the structure and function of flavoenzymes, (e) determination of the role of divalent metals in the mechanism of fibrillogenesis in amyloid formation, and (f) characterization of the mechanism of radical-mediated DNA strand scission and histone modification by novel organometallic complexes. Operation at Q-band is justified by the need for enhanced resolution of both EPR and ENDOR spectra, and the dual X- and Q-band operation is essential for success of multi-frequency approaches to constrain spectral simulation analyses. The projects supported by the requested EPR spectrometer cover investigations of the wide range of recognized biological radical reactivity, from "programmed" essential radicals in enzymes, to deleterious effects of free radicals and metals, to the use of radical reactivity as a therapeutic tool. A sustained high impact of the EPR spectrometer on biomedicine is therefore anticipated.