Acquisition of Pulsed EPR and ENDOR/ESEEM

该奖项提供资金，用于将连续波X波段电子顺磁共振(EPR)光谱仪升级为脉冲配置。脉冲EPR光谱仪将能够提供只有使用先进的EPR技术才能获得的结构信息，例如Endor(电子-核双共振)谱和ESEEM(电子自旋回波包络调制)谱。EPR用于检测含有未配对电子的材料中的分子和位置，例如存在于生物上重要的过渡金属铁、钴、铜、镍和锰中的分子和位置；存在于光合作用系统中的光诱导自由基中的分子和位置；由热解碳或金属氧化物组成的固体催化剂中的分子和位置，以及可以引入有机和生物分子中作为探针的永久自旋标记和自旋陷阱中的分子和位置。当最大限度地使用时，EPR是一种先进的结构工具(原理上类似于核磁共振光谱)，可以应用于冷冻或液体溶液中的大分子(不像X射线结晶学，需要高质量的晶体)，也可以应用于固体材料，如催化剂和吸附剂，没有大小限制(不像核磁共振光谱，除某些例外，只能对低于一定质量的大分子进行)。正在进行的项目包括：1)确定影响光合作用系统中有机辅因子氧化还原潜力的蛋白质因素；2)金属人工寡肽-DNA的检测；3)生物系统中蛋白质结合自由基的研究；4)硫酸盐-血红素酶的实验和理论研究；以及5)硫辛酸生物合成和丝氨酸脱氨酶的研究。使用该仪器进行的研究的一些社会效益包括：1)更好地了解硫酸盐连接的血红素蛋白中的氧转移化学，这可能导致改进的催化剂，用于工业应用。被研究的硫酸盐连接的血红素酶只使用电子、质子和氧气(或过氧化氢)来氧化底物。唯一的副产品是水。因此，这些酶是特别“绿色”的催化剂，能够模拟它们的化学作用的合成系统将具有明显的价值。2)对核糖核苷酸还原酶的生物化学有更深入的了解。这种酶对人类健康至关重要。3)深入了解生物/有机混合电化学半电池的设计和制造，该电池将光系统I与氢酶偶联，利用太阳光产生氢气。这一长期目标将导致一种仅利用阳光产生氢气的“绿色”方法。研究生和本科生将通过这种新仪器接受高级EPR方面的教育和培训。他们将接触到化学和生物学交界处的跨学科研究。学生将学习先进的光谱技术以及分子生物学和计算方法。这一奖项将扩大代表不足的群体获得先进仪器的机会。PI与当地本科生学院的教职员工持续合作。例如，萨斯奎哈纳大学的研究型本科生在学年期间在他们的家乡机构进行生物学研究，并在夏季在宾夕法尼亚州立大学进行EPR波谱研究。

This award provides funding to upgrade a continuous wave X-band electron paramagnetic resonance (EPR) spectrometer to a pulsed configuration. The pulsed EPR spectrometer will be able to provide structural information that is only accessible using advanced EPR techniques such as ENDOR (electron-nuclear double resonance) spectroscopy and ESEEM (electron spin echo envelope modulation) spectroscopy. EPR is used to detect molecules and sites in materials that contain unpaired electrons such as those that exist in the biologically important transition metals iron, cobalt, copper, nickel and manganese; in light-induced radicals in photosynthetic systems; in solid catalysts comprised of pyrolytic carbon or metal oxides with or without additional transition metals; and in permanent spin labels and spin traps that can be introduced into organic and biological molecules as probes. When used to its fullest capacity, EPR is an advanced structural tool (similar in principle to NMR spectroscopy) that can be applied to large molecules in frozen or liquid solution (unlike X-ray crystallography, which requires high-quality crystals) or to solid materials such as catalysts and adsorbents, with no size limit (unlike NMR spectroscopy, which, with certain exceptions, can only be performed on macromolecules below a certain mass). Ongoing projects affected by the acquisition of this instrument include: 1) Identification of Protein Factors that Influence the Redox Potentials of Organic Cofactors in Photosynthetic Systems; 2) Detection of Metallated Artificial Oligopeptide-DNA; 3) Study of Protein-Bound Radicals in Biological Systems; 4) Experimental and Theoretical Studies of Thiolate-Heme Enzymes; and 5) Elucidation of Lipoic Acid Biosynthesis and Study of Serine Deaminase. Some of the societal benefits of the research to be conducted with this instrument include: 1) A better understanding of oxygen transfer chemistry in thiolate-ligated heme-proteins, which could result in improved catalysts for industrial applications. The thiolate-ligated heme enzymes to be studied use only electrons, protons, and dioxygen (or peroxide) to oxidize substrates. The only by-product is water. Thus, these enzymes are particularly "green" catalysts, and synthetic systems that could mimic their chemistry would be of obvious value. 2) A better understanding of the biochemistry of ribonucleotide reductase. This enzyme has central importance in human health. 3) Insight into the design and fabrication of a biological/organic hybrid electrochemical half-cell that couples Photosystem I with hydrogenases to generate hydrogen gas using sunlight. This long-term goal would lead to a "green" method of generating hydrogen gas using sunlight alone.Graduate and undergraduate students will be educated and trained in advanced EPR with the new instrumentation. They will be exposed to interdisciplinary research at the border of chemistry and biology. Students will learn advanced spectroscopic techniques as well as molecular biology and computational methods. This award will broaden the access of underrepresented groups to advanced instrumentation. The PIs have ongoing collaborations with faculty at local undergraduate colleges. Research undergraduates at Susquehanna University, for example, carry out biological research at their home institution during the school year and perform EPR spectroscopy at Penn State during the summer.