STRUCTURAL INVESTIGATIONS OF METALLOPROTEIN METAL SITES

小分子的选择性识别和激活， 这一过程经常由金属蛋白介导，是 许多重要的生物系统。 理解能力和 选择性改变金属蛋白反应性， 的合理发展的重要影响 治疗剂。 对金属蛋白质的全面了解 然而，反应性取决于 金属活性部位的精确结构描述。 本提案的长期目标是确定 一系列金属酶的金属位点结构， 介导0/2/n-单元的反应性。 这将是 通过扩展X射线吸收精细 结构（EXAFS）光谱学和微分反常X射线 散射（DAS）。 EXAFS允许精确测定 直接协调环境（键长、协调 编号和配体身份），而DAS提供关于 更远（3-15 A）的金属-金属相互作用。 的制度 代表了几种不同的酶类别， 然而，对于每个系统，金属中心与 0/2/n-单元对生物学功能至关重要。 缺乏 合适的单晶排除了X射线晶体学的使用 研究这些系统和其他物理技术无法 提供可获得的详细结构信息 EXAFS和DAS。 待研究的系统是蓝色铜氧化酶漆酶， 非血红素铁加氧酶，其催化 邻苯二甲酸酯，一种来自乳杆菌属的含锰假过氧化氢酶 plantarum，辣根的锰取代衍生物 过氧化物酶和来自光合氧的Mn簇 复杂的进化 这些不同的结构比较 系统应允许更完整地了解 金属酶介导的活化的基本特征， 0/2/n-单位。

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.