LASER SPECTROSCOPY LABORATORY

本提案所要求的资金将用于支持制定一项 贝克曼研究所的激光光谱实验室。 仪表 在实验室将提供测量时间分辨 在10-11到102秒的时间尺度上的吸收和发射光谱。三 目前由NIH支持的研究项目将直接受益于 从这个仪器：（一）远程电子转移的研究 金属蛋白质;（ii）细胞色素中质子泵的研究 c氧化酶;和（iii）金属探针和药物结合的检查， DNA. 电子转移（ET）反应是基本的化学步骤 一系列生化变化的基础。 这些转移 经常发生在看似很长的距离上， 效率。 ET研究的目标是测试 目前的ET理论，并确定化学和物理 调节其效率的ET系统的特性。 细胞色素c 氧化酶是细胞呼吸的氧活化酶。 它有 据估计，有氧生物消耗的O2中有近90% 参与细胞色素c氧化酶的双氧化学， 在呼吸的最后一步变成水。的 细胞色素氧化酶的质子泵活性与其 电子转移反应性，相当大的努力是针对 确定了氧化还原键的位置，并阐明了 与氧化还原有关的质子转移反应。 过渡金属 复合物是生物技术中有前途的新工具，因为它们 识别核酸并与之反应的能力。 已经 证明了三（菲咯啉）金属络合物容易结合到 双链DNA，其中一些复合物将切割DNA后， 辐照 这项研究的目标是开发新的金属 结合到DNA上不同位点的复合物和用于 核酸结构 时间分辨激光光谱是一种重要的 在这三个研究项目中的工具。 的动力学 直接测量光诱导电子转移和复合 通过瞬态吸收光谱。 的构象变化 细胞色素氧化酶已被观察到的瞬态发射 光谱，辅以瞬态吸收。 测定 DNA结合模式，对映体偏好和结合方向 的混合配体配合物已经完成了通过时间分辨 钌（II）络合物的发射测量。 脉冲-激光 本提案中描述的仪器将提供以下能力 有必要进行这项研究。 在20 ps到20 ns的时间窗口中， 瞬态吸收测量将通过常规的 具有可调谐激发和白光的泵浦-探测光谱学 连续体作为探测器。 在较长的时间尺度上， 将用作瞬态吸收的激发源， 时间分辨发射实验

The funds requested in this proposal will support the development of a laser spectroscopy laboratory at the Beckman Institute. Instrumentation in the laboratory will provide for the measurement of time-resolved absorption and emission spectra on timescales from 10-11 to 102 s. Three research programs, currently supported by NIH, will directly benefit from this instrumentation: (i) studies of long-range electron transfer in metalloproteins; (ii) investigations of proton pumping in cytochrome c oxidase; and (iii) examinations of metal probes and drug binding to DNA. Electron-transfer (ET) reactions are the elementary chemical steps underlying a vast array of biochemical transformations. These transfers frequently occur over seemingly long distances with remarkable efficiencies. The goal of the ET research is to test the validity of current ET theories, and to identify the chemical and physical properties of ET systems that regulate their efficiencies. Cytochrome c oxidase is the oxygen-activating enzyme of cellular respiration. It has been estimated that nearly 90% of the 02 consumed by aerobic organisms participates in the dioxygen chemistry of cytochrome c oxidase and becomes reduced to water in the terminal step of respiration. The proton-pumping activity of cytochrome oxidase is linked to its electron-transfer reactivity, and considerable effort is directed toward identifying the site of redox linkage and unraveling the mechanism of the redox-linked proton translocation reaction. Transition metal complexes are promising new tools in biotechnology owing to their ability to recognize and react with nucleic acids. It has been demonstrated that tris(phenanthroline) metal complexes readily bind to double-stranded DNA, and some of these complexes will cleave DNA upon irradiation. The goal of this research is the development of new metal complexes which bind to different sites on DNA and new probes for nucleic acid structure. Time-resolved laser spectroscopy is a vital tool in all three of these research programs. The kinetics of photoinduced electron transfer and recombination are directly measured by transient absorption spectroscopy. Conformational changes in cytochrome oxidase have been observed by transient emission spectroscopy, complemented by transient absorption. The determination of DNA binding modes, enantiomeric preferences, and binding orientation of mixed ligand complexes has been accomplished through time-resolved emission measurements on ruthenium(II) complexes. The pulsed-laser instrumentation described in this proposal will provide the capabilities necessary to pursue this research. In the 20-ps to 20-ns time window, transient absorption measurements will be performed by conventional pump-probe spectroscopy with tunable excitation and a white-light continuum as a probe. On longer timescales, an excimer-pumped dye laser will be used as the excitation source for transient absorption and time-resolved emission experiments.