94 GHZ/9 GHZ CONTINUOUS WAVE AND PULSED EPR SPECTROMETER

本提案要求拨款购买布鲁克E-680 94千兆赫/ 9千兆赫连续波和脉冲电子顺磁共振波谱仪，供美国国立卫生研究院支助的密歇根州立大学6名研究人员组成的小组使用。该仪器将为主要用户群体提供新的实验能力，这将非常有利于他们正在进行的R-01和P-01资助的研究项目。94 GHz或w波段的能力将使我们能够解决目前X波段（9 GHz）光谱仪无法解决的金属生物化学问题。在脉冲模式下进行w波段EPR研究的能力可能会减轻高频率研究所预期的几个问题，例如使用磁场调制来探测宽吸收线的困难。对于位点定向自旋标记（SDSL）研究，w波段光谱仪将提供获得双标记蛋白质中氮氧化物之间精确距离所需的数据。X和w波段的脉冲EPR实验将为这些SDSL研究提供更详细的信息，从而获得更精确的结构信息。在两个微波频率下都可以使用连续波和脉冲ENDOR方法。在过去的15年里，西北大学的霍夫曼实验室率先在高场下进行ENDOR光谱分析，其优势包括提高了对小磁矩原子核研究的灵敏度，提高了光谱分辨率，并通过定向选择研究获得了更精确的结构信息。x波段的脉冲EPR能力将为主要用户提供二维EPR/ESEEM和时域检测技术，这将有利于一些拟议的研究。该仪器具有灵活的脉冲编程器，复杂的数据采集系统和样品探针，使其成为开发生物应用的绝佳平台。购买E-680光谱仪将使我们的开发工作从硬件建设转向解决生物医学问题。

This proposal requests funds for the purchase of a Bruker E-680 94 GHz/ 9GHz continuous-wave (cw) and pulsed Electron Paramagnetic Resonance spectrometer for use by a team of six NIH-supported investigators at Michigan State University. This instrument would provide new experimental capabilities to the major user group that would be very beneficial to their ongoing R-01 and P-01 funded research programs. The 94 GHz, or W-band, capability would allow us to address problems in metallobiochemistry that are not feasible with our current X- band (9 GHz) spectrometers. The ability to carry out W-band EPR studies in pulsed-mode may alleviate several of the problems anticipated with high frequency studies such as difficulties associated with using magnetic field modulation to detect broad absorption lines. For site- directed spin labeling (SDSL) studies, the W-band spectrometer will supply data required to obtain accurate distances between nitroxides in doubly-labeled proteins. Pulsed EPR experiments at both X- and W-band will provide more detailed information for these SDSL studies that will lead to more precise structural information. Cw and pulsed ENDOR methods will be available at both microwave frequencies. The advantages of performing ENDOR spectroscopy at high field have been pioneered by the Hoffman lab at Northwestern over the past 15 years and include enhanced sensitivity for studies of nuclei with small magnetic moments, improved spectral resolution and more precise structural information that stems from orientation-selective studies. The pulsed EPR capability at X-band will provide the major users with two- dimensional EPR/ESEEM and time domain detection techniques that will benefit several of the proposed studies. The instrument has a flexible pulse programmer, a sophisticated data acquisition system and a complement of sample probes that make it an excellent platform for the development of biological applications. Purchase of an E-680 spectrometer will shift our development efforts away from hardware building and towards solving biomedical problems.