TIME RESOLVED SPECTROSCOPY OF CYTOCHROME OXIDASES AND PGH SYNTHASES

这个项目的总体目标是了解氧气和过氧化物 激活和释放自由能的分子机制 在这些底物的还原中， 在细胞色素氧化酶和前列腺素H酶的化学。NS和PS 时间分辨共振拉曼光谱学，时间分辨光学 光谱，低温FTIR光谱，和电子磁- 共振技术将是主要的分析工具。最近 密歇根州立大学的技术进步， 我们用它们来研究突变型和野生型细胞色素氧化酶， 前列腺素合酶用细胞色素氧化酶，我们打算表征 质子传导进出活性位点的途径， 与O2减少和质子泵送相关; 可能参与金属中心的配体交换过程 将有针对性地研究它们在催化 周期在这些实验中，我们打算阐明 分子氧活化和还原化学的质子控制， 发生在细胞色素氧化酶中的方法， 电子转移到活性氧中间体释放的自由能 是用来驱动质子转移的对于前列腺素合酶， 将用时间分辨技术研究过氧化物的还原， 了解反应顺序和与酪氨酰自由基的偶联 阵随后的突变分析将靶向与以下相关的残基： 晶体结构对催化作用至关重要。

The overall goal of this project is to understand oxygen and peroxide activation and the molecular mechanisms by which the free energy released in the reduction of these substrates is couple to biologically useful chemistry in cytochrome oxidases and prostaglandin H synthases. Ns and ps time-resolved resonance Raman spectroscopy, time-resolved optical spectroscopy, low-temperature FTIR spectroscopy, and electron magnetic- resonance techniques will be the principal analytical tools. Recent technical advances to Michigan State with these spectroscopies will allow us to use them to study both mutant and wild-type cytochrome oxidase and prostaglandin synthase. With cytochrome oxidase, we intend to characterize pathways for proton conduction in and out of the active site that are relevant to both 02 reduction and proton pumping; specific residues that are potentially involved in ligand exchange processes at the metal centers will be targeted and studied in terms of their functions in the catalytic cycle. In these experiments, we intend to elucidate the means by which proton control of the dioxygen activation and reduction chemistry that occurs in cytochrome oxidase is implemented and the means by which the free energy released by electron transfer to reactive oxygen intermediates is used to drive proton translocation. For prostaglandin synthase, the reduction of peroxides will be studied with time-resolved techniques to understand the reaction sequence and the coupling to tyrosyl radical formation. Subsequent mutation analysis will target residues implicated by the crystal structure as being essential to the catalysis.