ELECTRON PARAMAGNETIC RESONANCE SPECTROMETER

我们寻求资金购买Bruker ESP-300E X波段电子设备 顺磁共振(EPR)光谱仪将取代17岁的瓦里安 不能再维护的E-109仪器。现建议： 为本仪器配备额外的Q频段电桥和腔体，Q-和 X波段李何恒温器，和一个双模腔。乐器是一把钥匙 这项工作由美国国立卫生研究院“主要”和“其他”的13项拨款资助。 用户组。主要用户群由教授组成。约翰·D·利普斯库姆 (P.I.)，Lawrence Que，Jr.，玛丽安·T·斯坦科维奇和威廉·B·托尔曼 这些个人和许多“其他”用户是该中心的成员 明尼苏达大学金属生物催化专业。许多 该小组内部的合作导致了联合出版物和 学生培训。EPR工具在生存能力方面发挥着重要作用 该中心及其所产生的合作。许多不同的类型 在生物学中以金属为中心的问题表现在 主要用户群研究。这些措施包括对这两家公司的调查 含有酶的单核和双核铁簇及其相关 模型系统.铜和血红素中氮代谢的研究 包括酶和模型体系；以及金属离子的研究。 黄素蛋白系统。所有这些研究都需要稳定的温度。 接近液氦的。请求Q波段附件是因为 需要研究不止一个的血红素、非血红素、锰和铜系统 频率，以便解释产生的复杂光谱 耦合或小零场分裂。几种酶和 正在研究的模型展示了来自整数自旋的新EPR信号 系统。这些信号已被证明是 酶催化循环中关键中间体的研究 如甲烷单加氧酶(MMO)。整数自旋信号强度为 使用所需的双模腔体观察时，增强了约3倍 由于选拔规则与半决赛的规则不同 整型自旋系统是EPR研究的常见目标。另外， 消除了由半整数自旋系统产生的背景信号 当使用双模容量时。整数自旋信号通常具有 零磁场的强度，因为X波段的量子是可比的 能量转化为零场分裂。更高能量Q频段的使用 原则上，量子将允许对这些问题进行更全面的研究 整数自旋系统。目前的EPR系统已被大量用于 它的整个使用寿命，并继续有很高的需求。它有 已向整个研究社区免费提供。这个 新的工具将使我们能够延续这一传统，并促进 向Endor等新领域扩张，但这些领域不容易实施 用当前的乐器。一家专门为 EPR是医学院基础科学大楼的一部分，目前正在 建筑。这将允许将仪器放置在 5其他分子结构核心设施以及相关的 技术人员。

We seek funding to purchase a Bruker ESP-300E X-band electron paramagnetic resonance (EPR) spectrometer to replace a 17 year old Varian E-109 instrument that can no longer be maintained. It is proposed to equip this instrument with an additional Q-band bridge and cavity, Q-and X-band Li He cryostats, and a dual mode cavity. The instrument is a key element in the work funded by 13 NIH grants from the "major" and "other" users groups. The major users group consists of Profs. John D. Lipscomb (P.I.), Lawrence Que, Jr., Marian T. Stankovich, and William B. Tolman. These individuals and many of the "other" users are members of the Center for Metals in Biocatalysis at the University of Minnesota. Many collaborations within this group have led to joint publications and student training. The EPR instrument plays a major role in the viability of this Center and the collaborations it engenders. Many different types of problems centered around metals in biology are represented in the research of major users group. These include investigations of both mononuclear and dinuclear iron cluster containing enzymes and relevant model systems; investigation of nitrogen metabolism in Cu and heme containing enzymes and model systems; and investigations of metallo- flavoprotein systems. All of these studies require stable temperatures near that of liquid helium. The Q band accessory is requested due to the need to investigate heme, nonheme, Mn, and Cu systems at more than one frequency in order to interpret the complex spectra that arise from coupling or small zero field splitting. Several of the enzymes and models under investigation exhibit novel EPR signals from integer spin systems. These signals have proven to be important tools in the investigation of key intermediates in the catalytic cycles of enzymes such as methane monooxygenase (MMO). Integer spin signal intensity is enhanced about 3-fold when observed using the requested dual mode cavity due to a difference in the selection rules versus those of the half integer spin systems that are the usual targets of EPR studies. Also, the background signals due to half integer spin systems are eliminated when the dual mode capacity is used. Integer spin signals often have intensity at zero magnetic field because the X-band quantum is comparable in energy to the zero field splitting. Use of the higher energy Q-band quantum will, in principle, allow more complete investigation of these integer spin systems. The current EPR system has been heavily used for its entire service lifetime and continues to be in high demand. It has been made available to the entire research community free of charge. The new instrument will allow us to continue this tradition and facilitate expansion into new areas such as ENDOR that cannot be readily implemented with the current instrument. A new laboratory designed specifically for EPR is part of the medical school basic sciences building currently under construction. This will allow the instrument to be placed adjacent to 5 other molecular structure core facilities as well as the relevant technical personnel.