BIOLOGICAL METAL CLUSTERS--BIOPHYSICAL AND MODEL STUDIES

描述：需要两种或多种金属的酶和蛋白质活性位点 活性中心现在是生物化学的显著特征。 示例 生物金属簇的已知涉及Fe原子（例如， 铁氧化还原酶、亚硫酸盐还原酶、血红蛋白、核糖核苷酸还原酶， 甲烷单加氧酶），Cu原子（例如血蓝蛋白，酪氨酸酶， 铜蓝蛋白，细胞色素氧化酶中的CuA），Mn原子（例如光系统II， 过氧化氢酶）、Ni原子（尿素酶）和多于一种金属，或 异多核簇（例如超氧化物歧化酶，Cu，Zn;固氮酶， 钼，铁;细胞色素氧化酶，血红素a3，铜B;氢化酶，乙酰辅酶A 合成酶、一氧化碳脱氢酶、Ni、Fe）。 的多种功能 簇包括电子传输，质子梯度的建立， 双氧结合，双氧活化，DNA合成，水解 反应和氧化还原反应，包括二氮和二氧还原 以及二氢、CO和水的氧化。 虽然有多名 生物金属簇的特征，只有在少数 实例具有与多核活性相关的独特性质， 地点已划定。 对于异多核的情况尤其如此。 集群 拟议研究的最终目标是了解 与金属簇催化相关的优点以及每种金属簇如何 为特定目的而设计。 这些知识将提供详细的 了解涉及金属簇的酶机制，并将有助于 酶抑制剂（如药物）和工业催化剂的设计 所涉及的化学反应。 这一建议的重点是了解 含镍氢化酶的结构和功能， 微生物厌氧代谢中的酶，最近已经证明， 含有一个新的异双核Ni，Fe活性中心。 因此，拟议的 研究还影响了我们对Ni的生物学作用的理解， 其中包括幽门螺杆菌的生殖力， 与胃溃疡和胃癌有关。 具体目标： 氢化酶的结构和功能包括：（1）建立了 催化剂中活性中心Ni和Fe中心之间的关系 机制，（2）确定Ni和Fe位的功能，包括 金属配体，和（3）阐明酶催化的优点 与异双核位点和Se的掺入相关。这些 目标将通过使用物理技术的组合来实现， 氢化酶和设计用于模拟特异性氢化酶的模型系统 酶活性位点的结构或功能方面。

DESCRIPTION: Enzyme and protein active sites that require two or more metal centers for activity are now prominent features of biochemistry. Examples of biological metal clusters are known that involve Fe atoms (e.g. ferredoxins, sulfite reductase, hemerythrin, ribonucleotide reductase, methane monooxygenase), Cu atoms (e.g. hemocyanin, tyrosinase, ceruloplasmin, CuA in cytochrome oxidase), Mn atoms (e.g. photosystem II, catalase), Ni atoms (urease), and more than one kind of metal, or heteropolynuclear clusters (e.g. superoxide dismutase, Cu, Zn; nitrogenase, Mo, Fe; cytochrome oxidase, heme a3, CuB; hydrogenase, acetyl coenzyme A synthase, carbon monoxide dehydrogenase, Ni, Fe). The diverse functions of the clusters include electron transport, establishment of proton gradients, dioxygen binding, dioxygen activation, aspects of DNA synthesis, hydrolytic reactions, and redox reactions including dinitrogen and dioxygen reduction and dihydrogen, CO and water oxidation. Despite the large number of biological metal clusters that have been characterized, only in a few instances have the unique properties associated with polynuclear active sites been delineated. This is particularly true for heteropolynuclear clusters. The ultimate goals of the proposed research are to understand the advantages associated with catalysis by metal clusters and how each is designed for its specific purpose. This knowledge will provide a detailed understanding of enzyme mechanisms involving metal clusters and will aid in the design of inhibitors of enzymes (e.g. drugs) and industrial catalysts for the chemical reactions involved. This proposal focuses on understanding the structure and function of Ni-containing hydrogenases, which are key enzymes in anaerobic metabolism in microbes and have recently been shown to contain a novel heterodinuclear Ni, Fe active site. Thus, the proposed research also impacts on our understanding of the biological roles of Ni, which include the virility of Helicobacter pylori, a bacterium that has been associated with gastric ulcers and stomach cancer. Specific goals regarding the structure and function of hydrogenase include: (1) establishing the relationship between the active site Ni and Fe centers in the catalytic mechanism, (2) determining the functions of the Ni and Fe site, including the metal ligands, and (3) elucidating the advantages to enzyme catalysis associated with a heterodinuclear site and with incorporation of Se. These goals will be met by using a combination of physical techniques applied to hydrogenases and to model systems that are designed to model specific aspects of the structure or function of the enzyme active site.