UPGRADE OF VARIABLE FREQUENCY PULSED EPR FACILITY

描述(由申请人提供)： 该提案要求提供资金，通过购买一个高场(1.99特斯拉)磁体系统、带有附件和温度控制器的液氦低温恒温器以及一个定时/数据采集模块，对亚利桑那大学化学系的变频脉冲EPR设施进行大幅升级。目前，作为Bruker ESP300E X波段连续EPR光谱仪组成部分的单个1.4特斯拉磁体系统还必须满足在2-8 GHz、8-18 GHz和26-40 GHz范围内运行的三台独特的宽带脉冲EPR光谱仪的要求。这种安排极大地限制了EPR设施的研究产出，因为一次只能运行一种类型的EPR实验。此外，单个可用的磁体系统的光谱仪之间的频繁更换占用了宝贵的仪器时间，这些时间可以用于生产性研究。此外，现有磁体的1.4特斯拉磁场太低，无法用40 GHz附近的高分辨率脉冲EPR技术研究g&lt；2.0的EPR信号。这一高频范围对于这项提议的研究人员的几个生物分子的脉冲EPR研究是必不可少的，包括研究血红素蛋白和Rieske蛋白中的14N，15N相互作用和钼酶中的17-O，所有这些都具有g=2以下的g值。所请求的1.99特斯拉磁体系统，带有附件和温度控制器的液氦低温恒温器，以及一个定时/数据采集模块，将利用现有的8-18和26-40 GHz脉冲宽带电子顺磁共振光谱仪满足日益增长的对金属生物分子实验的需求，并为用户提供更多使用连续X波段和脉冲S/C波段(2-8 GHz)光谱仪的机会。

DESCRIPTION (provided by applicant): This proposal requests funding to substantially upgrade the variable frequency pulsed EPR Facility in the Department of Chemistry at the University of Arizona by acquiring a high field (1.99 Tesla) magnet system, including power supply, liquid helium cryostat with accessories and temperature controller, and a timing/ data acquistion module. Presently, a single 1.4 Tesla magnet system that is an integral part of the Bruker ESP300E X-band CW EPR spectrometer must also serve the requirements for the three unique broadband-pulsed EPR spectrometers that operate over the 2-8, 8-18 and 26-40 GHz ranges. This arrangement greatly limits the research output of the EPR Facility because only one type of EPR experiment can be running at any one time. In addition, the frequent changing among the spectrometers for the single available magnet system usurps valuable instrument time that could be used for productive research. Moreover, the 1.4 Tesla field of the existing magnet is too low to enable EPR signals with g < 2.0 to be studied by high resolution pulsed EPR techniques near 40 GHz. This high frequency range is essential for pulsed EPR studies of several of the biomolecules of the investigators of this proposal, including investigation of 14N, 15N interactions in heme proteins and Rieske proteins and 17-O in molybdenum enzymes, all of which have g-values spread below g=2. The requested 1.99 Tesla magnet system with power supply, liquid helium cryostat with accessories and temperature controller, and a timing/data acquisition module, will handle the ever increasing demands for experiments on metallobiomolecules using the existing 8-18 and 26-40 GHz pulsed broadband EPR spectrometers as well as provide increased access of users to the CW X-band and pulsed S/C band (2-8 GHz) spectrometers.