Crystallographic Studies of Electron Tranfer Proteins

固氮酶是负责生物固氮的酶，由两种金属蛋白质组成， 蛋白质和MoFe蛋白质，介导ATP水解与二氮还原的偶联， 氨固氮酶是具有多种不同铁硫簇的酶的典型例子， 参与电子转移和底物还原，以及提供一个很好的模型， ATP水解的转导。我们正在寻求协调的生化和结晶学方法 以确定固氮酶蛋白的特定状态的三维结构， 配合物我们的研究目标强调生物化学，生物物理和结构表征， 在周转条件下被捕获的固氮酶蛋白质;金属部位氧化状态的评估 通过在多个波长下的晶体学精修在固氮酶蛋白的不同形式中; 与核苷酸复合的固氮酶蛋白的制备和分析， 电子供体。结构和生物化学研究将扩展到其他能量转换 系统，特别是完整膜蛋白ATP结合盒（ABC）转运蛋白家族， 评估我们关于核苷酸依赖性转导机制的结论的一般性 流程.一个高度优先的任务是完成我们目前对ABC转运蛋白的结构研究， 输入到细胞中的金属螯合物种类和氨基酸，然后进行结构和生物化学分析， 这些转运蛋白与核苷酸和结合蛋白的确定复合物的表征。这些 研究将扩展到与金属代谢有关的其他转运蛋白。 电子传递和ATP依赖的转导过程构成细胞能量代谢的核心。 固氮酶不仅将这些元素偶联以产生必需的营养素，而且还作为一种 参与信号和能量转导途径的蛋白质的优秀结构模型，包括G- 蛋白质和ras癌基因。ABC转运蛋白的研究将拓展我们对ABC转运蛋白结构和机制的认识 专注于ATP依赖的过程，广泛的家庭的完整膜蛋白，包括 多药耐药性和囊性纤维化的生物医学相关成员。

Nitrogenase, the enzyme responsible for biological nitrogen fixation, consists of two metalloproteins, the Fe- protein and MoFe-protein, that mediate the coupling of ATP hydrolysis to the reduction of dinitrogen to ammonia. Nitrogenase is a prototypic example of an enzyme with multiple and varied iron-sulfur clusters that participate in electron transfer and substrate reduction, as well as providing an excellent model for energy transduction of ATP hydrolysis. We are pursuing coordinated biochemical and crystallographic approaches to determine the three-dimensional structures of defined states of the nitrogenase proteins individually and in complexes. Our research objectives emphasize biochemical, biophysical and structural characterization of nitrogenase proteins trapped under turnover conditions; an assessment of the oxidation states of metal sites in different forms of the nitrogenase proteins through crystallographic refinement at multiple wavelengths; and preparation and analysis of the nitrogenase proteins complexed with nucleotides and physiological electron donors. The structural and biochemical studies will be extended to other energy transduction systems, specifically the family of integral membrane protein ATP Binding Cassette (ABC) transporters, to assess the generality of our conclusions concerning the mechanisms of nucleotide dependent transduction processes. A high priority is to complete our current structural studies of ABC transporters mediating the import into cells of metal-chelate species and amino acids, followed by structural and biochemical characterization of defined complexes of these transporters with nucleotides and binding proteins. These studies will be extended to additional transporters implicated in metal metabolism. Electron transfer and ATP dependent transduction processes form the heart of cellular energy metabolism. Nitrogenase not only couples these elements to generate an essential nutrient, but also serves as an excellent structural model for proteins participating in signal and energy transduction pathways, including G- proteins and the ras oncogene. The study of ABC transporters will extend our structural and mechanistic focus on ATP dependent processes to a widespread family of integral membrane proteins, including biomedically relevant members responsible for multidrug resistance and cystic fibrosis.