MRI: Development of a 260 GHz Pulse EPR/DEER Spectrometer

在主要研究仪器项目（MRI）和化学研究仪器项目（CRIF）的支持下，加州大学戴维斯分校（UCD）化学系的R. David Britt教授和UCD电气与计算机工程系的同事Neville Luhmann，以及来自加州、俄勒冈州的多位高级人员，马萨诸塞州和佛罗里达州将开发一种脉冲EPR光谱仪，该光谱仪将工作在高频（260 GHz），低功率（50 W）和带宽（20 GHz），能够进行电子核双共振（ENDOR）方法和双电子-电子共振（DEER）。该光谱仪设计的核心是一个紧凑的260 GHz片束行波管（SBTWT）放大器，工作电压为20 kV，脉冲占空比为1%。该设计是在DARPA HiFIVE计划下开发的220 GHz SBTWT的基础上进行的。一个工业合作伙伴（12号桥）也将参与其中。一般来说，EPR光谱仪产生分子和固态材料的几何和电子结构的详细信息。它还可用于获取自由基的寿命信息，这些自由基是参与有价值的化学转化以及病理性肿瘤生长起始的短命、高活性物质。这些研究将影响许多领域，从无机和有机分子的合成到新型固态材料的开发，再到磁性和生物化合物。重要的是，学生的参与将有助于培养新一代的乐器演奏家。该奖项将产生一种能够在各个跨学科领域进行一系列高影响力研究的仪器，同时涉及美国各地的多个部门。该奖项旨在加强各级的研究和教育，特别是在以下领域：(a)使用Gd(III)-DPTA标签；(b)研究GPCR信号转导蛋白的激活机制；(c)研究金属如何与抗菌钙保护蛋白s100家族蛋白结合；(d)利用ENDOR探测具有催化活性的锤头核糖体Mn取代形式的高亲和力Mn（II）结合位点；(e)研究细菌多铜氧化酶MnxG对二氧化锰生物矿化过程中Mn（II）的氧化作用；(f)研究蓝藻的生物钟；(g)分析金属离子结合对DNA聚合酶活性的影响；(h)研究金属离子结合如何影响多种具有Cu（II）和Zn（II）结合结构域的蛋白质的折叠和错误折叠；(i)研究用于太阳能燃料系统的水氧化和氢还原催化剂。

With this award from the Major Research Instrumentation Program (MRI) and support from the Chemistry Research Instrumentation Program (CRIF), Professor R. David Britt from the Department of Chemistry at the University of California-Davis (UCD) and colleague Neville Luhmann from the Department of Electrical and Computer Engineering at UCD as well as various senior personnel from California, Oregon, Massachusetts and Florida will develop a pulsed EPR spectrometer that will work at a high frequency (260 GHz), with low power (50 W), and bandwidth (20 GHz) capable of carrying out electron nuclear double resonance (ENDOR) methods and double electron-electron resonance (DEER). The heart of the spectrometer design is a compact 260 GHz Sheet Beam Traveling Wave Tube (SBTWT) amplifier operating at a voltage of 20 kV with a 1% pulse duty cycle. The design is scaled from that of a 220 GHz SBTWT developed under the DARPA HiFIVE program. An industrial partner (Bridge 12) is also going to be involved. In general, an EPR spectrometer yields detailed information on the geometric and electronic structure of molecular and solid state materials. It may also be used to obtain information about the lifetimes of free radicals, short-lived, highly reactive species involved in valuable chemical transformations as well as the initiation of pathological tumor growth. These studies will impact a number of areas, from the synthesis of inorganic and organic molecules to the development of new solid state materials to compounds of magnetic and biological interest. Importantly, participation of students will allow preparation of the new generation of instrumentalists.This award will produce an instrument capable of carrying out a series of high impact research in various interdisciplinary fields while involving multiple departments across the United States. The award is aimed at enhancing research and education at all levels, especially in areas such as (a) using Gd(III)-DPTA labeling; (b) studying mechanisms of activation in proteins of GPCR signal transduction; (c) studying how metals bind to the antimicrobial Calprotectin S100-family protein; (d) using ENDOR to probe a high affinity Mn(II) binding site in the catalytically active Mn-substituted form of the hammerhead ribosome; (e) studying oxidation of Mn(II) in manganese dioxide biomineralization by the bacterial multicopper oxidase MnxG; (f) studying the circadian clock of cyanobacteria; (g) analyzing the effects of metal ion binding in activity of DNA polymerase; (h) studying how metal ion binding affects protein folding and misfolding in a variety of proteins with Cu(II) and Zn(II) binding domains; (i) studying water oxidation and hydrogen reduction catalysts to be employed in solar fuel systems.