BIOLOGICAL METAL CLUSTERS BIOPHYSICAL & MODEL STUDIES

含有两个或两个以上相互作用的酶和蛋白质活性部位 金属中心现在在矿物生物化学中扮演着重要的角色。系统 包含由铁原子组成的金属团簇(例如，铁还蛋白， 亚硫酸盐还原酶、氯氰菊酯、酪氨酸酶、铜蓝蛋白、细胞色素 酶)、锰原子(光系统II、过氧化氢酶)和一个以上 元素，或杂多核团簇(例如，固氮酶-Mo，Fe； 细胞色素氧化酶-铁、铜、氢酶和一氧化碳 脱氢酶--Ni、Fe)已鉴定。的最终目标 这个项目是为了阐明金属团簇的结构。 金属蛋白，以确定这些簇在 蛋白质的功能，并了解大自然是如何设计 为特定目的而聚集。这一知识将提供一个 对生物过程的详细了解，将有助于 多种药用酶抑制剂和催化剂的设计 反应。在本报告所述期间，我们完成了 11种变色菌中镍中心的结构 氢酶。这些研究得出了三个重要结论 与酶的结构和功能有关。第一，倪妮-S 距离最多相差约0.15 E，而不是建议的0.4 E 通过结晶学信息。第二，有一个振荡在 在待定酶样品中观察到的边缘能量 表明活性中心有两种氧化还原状态的构象 (氧化和还原)，这些状态只有一个电子不同。 最后，活性中心中的Ni-Fe距离从 长距离(约2.8 E)到短距离(2.5 E)，即 与活性部位的减少相关。这可能是由于 底物的结合或溶剂衍生O-给体的丢失 还原时桥联配体。

Enzyme and protein active sites containing two or more interacting metal centers now figure prominently in metallobiochemistry. Systems containing metal clusters composed of Fe atoms (e.g., ferredoxins, sulfite reductase, hemerythrin, tyrosinase, ceruloplasmin, cytochrome oxidase), Mn atoms (photosystem II, catalase), and more than one element, or heteropolynuclear clusters (e.g., nitrogenase-Mo,Fe; cytochrome oxidase-Fe,Cu, hydrogenase and carbon monoxide dehydrogenase- Ni,Fe) have been identified. The ultimate goals of this project are to elucidate the structures of the metal clusters in metalloproteins, to determine the roles these clusters serve in the function of the protein , and to understand how nature designs a cluster for a specific purpose. This knowledge will provide a detailed understanding of biological processes and will aid in the design of pharmaceutical enzyme inhibitors and catalysts for various reactions. During the current report period, we completed studies of the structures of the Ni sites in eleven forms of Chromatium vinosum hydrogenase. These studies lead to three important conclusions related to the enzyme structure and function. First, the Ni-S distances differ by at most ~ 0.15 E, rather than 0.4 E as suggested by crystallographic information. Second, there is an oscillation in the edge energy observed in samples from enzyme in a ready conformation that indicates that the active site has two redox states (oxidized and reduced) and that these states differ by one electron. Last, there is a change in the Ni-Fe distance in the active site from a long distance (ca. 2.8 E) to a short distance (2.5 E) that is correlated with the reduction of the active site. This may be due to the binding of substrate or the loss of a solvent-derived O-donor bridging ligand upon reduction.