STRUCTURAL INVESTIGATIONS OF METALLOPROTEIN METAL SITES

小分子的选择性识别和激活 经常由金属蛋白介导的过程是 许多重要的生物系统。理解和理解 选择性地修饰金属蛋白的反应性 对科学发展的重要启示 治疗剂。对金属蛋白的全面理解 然而，反应性取决于可用的 金属活性中心的准确结构描述。 这项建议的长期目标是确定 一系列金属酶的金属中心结构 调节0/2/n单元的反应性。这将是 通过扩展X射线吸收精细实现的 结构(EXAFS)谱与微分反常X射线 散射(DAS)。EXAFS允许精确确定 直接协调环境(键长、协调 数字和配基身份)，而DAS提供有关 更远距离(3-15A)的金属-金属相互作用。系统可用于 被研究代表几种不同的酶类， 然而，对于每个系统，金属中心与 0/2/n单位对生物功能至关重要。缺乏 合适的单晶排除了X射线结晶学的使用 研究这些系统和其他物理技术是无法 提供可获得的详细结构信息 来自EXAFS和DAS。 要研究的系统是蓝色铜氧化物漆酶，a 催化氧化的非血红素铁加氧酶 邻苯二甲酸盐--乳杆菌产生的一种含锰假焦糖酶 车前草，辣根的锰取代衍生物 过氧化物酶，以及来自光合氧的锰团簇 不断演变的情结。这些不同之处的结构比较 系统应该允许更完整地理解 金属酶介导的细胞活化的基本特征 0/2/n-单元。

The selective recognition and activation of small molecules, a process frequently mediated by metalloproteins, is at the heart of many crucial biological systems. The ability to understand and selectively modify metalloprotein reactivity would have important implications for the rational development of therapeutic agents. Complete understanding of metalloprotein reactivity is dependent, however, on the availability of an accurate structural description of the metal active site. The long-range objective of this proposal is determination of the metal-site structure for a series of metalloenzymes which mediate the reactivity of the 0/2/n- unit. This will be accomplished by means of extended X-ray absorption fine structure (EXAFS) spectroscopy and differential anomalous X-ray scattering (DAS). EXAFS allows precise determination of the immediate coordination environment (bond length, coordination number and ligand identity) while DAS provides information about more distant (3-15 A) metal-metal interactions. The systems to be studied represent several different enzymatic categories, however for each system the reactivity of the metal center with the 0/2/n- unit is crucial to the biological function. The lack of suitable single crystals precludes the use of X-ray crystallography to study these systems and other physical techniques are unable to provide the detailed structural information which can be obtained from EXAFS and DAS. The systems to be studied are the blue copper oxidase laccase, a non-heme iron oxygenase which catalyzes the oxidation of phthalate, a Mn containing pseudocatalase from Lactobacillus plantarum, the Mn substituted derivative of horseradish peroxidase, and the Mn cluster from the photosynthetic oxygen evolving complex. Structural comparisions of these different systems should permit a more complete understanding of the essential features of metalloenzyme mediated activation of the 0/2/n- unit.