LIGAND BRIDGED BINUCLEAR METAL COMPLEXES AND PROTEINS.

这项研究的主要目的是阐明化学和 蛋白质中配体桥连的双中心的物理性质， 相关模型化合物 具体注意力将集中在设计上， 的小分子类似物的合成和表征 以含铁和铜的蛋白质为核心。 三种主要类别的 将研究复合物。 第一种是二铁（Fe 2）化合物，其具有 μ-氧代和两个桥接羧酸根配体，与已知的 携带氧气的海洋无脊椎动物呼吸系统的结构 血红蛋白 二铁中心也是已知的或假定存在的 在至少三种其他重要的蛋白质中， 3-脱氧-D-阿拉伯庚酮糖酸7-磷酸（DAHP）合酶，第一个 参与细菌中常见芳香族生物合成途径的酶， 植物，核糖核苷酸还原酶，负责催化 DNA合成中独特的第一步，以及紫色酸性磷酸酶。 的 第二类是双核铜（Cu 2）化合物， 大环配体，并被设计为促进双氧的可逆结合 类似于节肢动物和软体动物的双核铜中心 呼吸蛋白血蓝蛋白 双核铜中心普遍存在于 生物学，存在于酪氨酸酶，漆酶，铜蓝蛋白，和各种 其他利用分子氧的酶。 铁卟啉 螯合臂与铜配位构成第三类络合物， 被研究。 这些杂环配合物将作为模型， 细胞色素c氧化酶中的配体桥接Fe/Cu中心，细胞色素c氧化酶是细胞色素c氧化酶的末端酶， 呼吸氧化还原链 所有化合物将进行表征 通过X射线晶体学和ESR或NMR磁共振在结构上 方法. 磁、电子和振动光谱 将测量其性质并与蛋白质的性质进行比较， 优化和校准现有的结构分配。 这些分子与分子氧可逆结合的原理 将研究配体桥接的双中心。 选定研究 的金属蛋白质将包括体磁化率，如果 技术上可行的63 Cu/65 Cu NMR光谱测量。 的 该项目将提供有关几个核电站的基本知识 在生物学中负责运输和利用分子氧， 用于基本的酶促过程。

The major objective of this research is to elucidate the chemical and physical properties of ligand-bridged bimetallic centers in proteins and related model compounds. Specific attention will focus on the design, synthesis, and characterization of small molecule analogs of the bimetallic cores in iron and copper containing proteins. Three major classes of complexes will be studied. The first are diiron (Fe2) compounds having a Mu-oxo and two bridging carboxylate ligands, congruent with the known structure of the dioxygen (O2) carrying marine invertebrate respiratory protein hemerythrin. Diiron centers are also known or postulated to exist in at least three other important proteins including 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase, the first enzyme involved in the common aromatic biosynthetic pathway in bacteria and plants, ribonucleotide reductase, the enzyme responsible for catalyzing the first unique step in DNA synthesis, and the purple acid phosphatases. The second class are dicopper (Cu2) compounds incorporated into binucleating macrocyclic ligands and designed to promote reversible binding of dioxygen analogous to the binuclear copper centers in the arthropod and mollusc respiratory protein hemocyanin. Binuclear copper centers are ubiquitous in biology, occurring in tyrosinase, laccase, ceruloplasmin, and a variety of other enzymes that utilize dioxygen. Iron porphyrins with an attached chelating arm to coordinate copper comprise the third class of complex to be studied. These heterobimetallic complexes will serve as models for the ligand-bridged Fe/Cu center in cytochrome c oxidase, the terminal enzyme in the respiratory redox chain. All compounds will be characterized structurally by X-ray crystallography and ESR or NMR magnetic resonance methods. The magnetic, electronic, and vibrational spectroscopic properties will be measured and compared with those of the protein bimetallic cores to refine and calibrate existing structural assignments. The principles involved in the reversible binding of dioxygen by these ligand-bridged bimetallic centers will be investigated. Selected studies of the metalloproteins will include bulk magnetic susceptibility and, if technically feasible, 63Cu/65Cu NMR spectroscopic measurements. The project will provide fundamental knowledge about several bimetallic centers in biology responsible for the transport and utilization of dioxygen and for essential enzymatic processes.