Rapid Kinetic and Other Studies of Biological Oxygenases

项目描述（申请人提供）：本项目是对加氧酶和其他氧化还原酶的结构和功能的多学科研究。主要重点是如何氧是激活Rieske加氧酶和细胞色素P450。此外，其他金属蛋白的合作研究也在进行中。加氧酶存在于所有需氧生物体中，并且在类固醇、核酸、儿茶酚胺、胶原、药物、胡萝卜素、木质素和各种外来化合物的生物合成、转化和降解中是重要的。因此，这些酶对大多数有氧生命形式是至关重要的，并且对于处理环境污染所必需的生物修复过程的发展是必需的，环境污染是世界上主要的健康问题之一。我们将详细研究邻苯二甲酸酯双加氧酶（PDO）的物理、化学和动力学性质，催化许多芳香族化合物有氧代谢的第一步的Rieske加氧酶的范例。Rieske非血红素含铁酶催化的产物除了在生物降解中的作用外，还常常是顺式二氢二醇，这在“绿色”合成化学中是有价值的。我们将描述参与氧化反应的中间体。此外，我们将调查（与M.J.库恩和J.道森合作）的中间体参与细胞色素P450的氧化过程的几个方面。我们的假设是，平行研究这两种类型的系统相对于基板和产品，和中间体参与，将是互补的发展这些氧化过程的更深入的了解。拟议的研究将采用快速动力学光谱，化学淬灭，和其他酶学方法。X射线晶体学和遗传技术，包括克隆，表达和诱变，也将用于更好地了解蛋白质如何催化这些有趣的反应。我们的方法将是修改活性位点残基，然后通过各种物理技术研究如何影响催化的各个步骤，我们相信，这些研究的结果将导致更好地了解分子氧是如何被激活的控制代谢过程。这反过来可能导致预测各种化合物如何在环境中代谢的能力提高。

DESCRIPTION (provided by applicant): This project is a multi-disciplinary study of the structure and function of oxygenases and other redox enzymes. The principle focus is on how oxygen is activated by Rieske oxygenases and on cytochromes P450. In addition, collaborative studies of other metalloproteins are also being carried out. Oxygenases are found in all aerobic organisms and are important in the biosynthesis, transformation, and degradation of steroids, nucleic acids, catecholamines, collagen, drugs, prostaglandins, lignin, and various foreign compounds. Thus, these enzymes are crucial to a majority of aerobic life forms and are requisite to the development of bioremediation processes necessary for dealing with pollution in our environment, one of the major health problems of the world.We will investigate in detail the physical, chemical, and kinetic properties of phthalate dioxygenase (PDO), a paradigm for the Rieske oxygenases that catalyze the first step in the aerobic metabolism of many aromatic compounds. In addition to their role in biodegradation, the products of Rieske nonheme iron-containing enzyme catalysis are often cis-dihydrodiols, which are valuable in "green" synthetic chemistry. We will characterize intermediates that are involved in the oxygenation reaction. In addition, we will investigate (in collaboration with M.J. Coon and J. Dawson) several aspects of intermediates involved in oxygenation processes by cytochromes P450. Our hypothesis is that parallel studies of these two types of systems with respect to substrates and products, and intermediates involved, will be complementary to developing a deeper understanding of these oxygenative processes. The proposed studies will employ rapid kinetics spectroscopy, chemical quenching, and other enzymological methods. X-ray crystallography and genetic techniques, including cloning, expression, and mutagenesis, will also be used to develop a better understanding of how the proteins catalyze these interesting reactions. Our approach will be to modify active site residues, and then to study by a variety of physical techniques how various steps in catalysis are affected.We believe that results from these studies will lead to a better understanding of how molecular oxygen is activated for controlled metabolic processes. This may, in turn, lead to an improved ability to predict how various compounds will be metabolized in the environment.