Structural and spectroscopic analysis of multi-centered metallo enzymes and their functional complexes involved in nitrate- and sulfate-respiration

电子转移过程在维持生命方面起着关键作用。实际上，所有的生物能源转换系统都采用氧化还原级联。铁和铜是参与这些过程的中介和催化作用的蛋白质的主要活性中心。在该项目中，我们希望通过结构(高结果X射线结晶学)和光谱方法(EPR/Endor，Mössbauer，共振拉曼)表征涉及(I)硝酸盐-氨化和(Ii)硫酸盐-呼吸作用的几个主要模块。在这些过程中，硝酸盐(--NH_3)或硫酸盐(--H_2S)充当电子受体。基于这些构件的结构和光谱特征，将得到活性中心的电子和磁图，这将有助于理解一个模块中催化中心的功能，并有助于定义分子内和分子间的电子路径。主要目标将是：(I)来自硝酸盐氨化细菌的细胞色素c亚硝酸盐还原酶复合体，一个具有新的结构基序和光谱性质的多血红素系统，以及(Ii)来自硫酸盐还原细菌的腺苷-5‘-磷酸硫酸盐还原酶和十二氢血红素蛋白。

Electron transfer processes play a key role in maintaining life. Practically all biological energy conversion systems employ redox cascades. Fe and Cu are among the predominant active centers of proteins involved with mediation and catalysis of these processes. In the project we want to characterize by structural (high-resulation X-ray crystallography) and spectroscopic methodes (EPR/ENDOR, Mössbauer, resonance Raman) several main modules involved in (i) nitrate-ammonification, and (ii) sulfate-respiration. In these processes either nitrate (-» NH3) or sulfate (-» H2S) serve as electron acceptors. Based on the structural and spectroscopic features of these building blocks an electronic and magnetic picture of the active sites will be derived which will help in understanding the function of the catalytic centers within one module, and which will help in defining intra- and intermolecular electron pathways. Main targets will be: (i) the cytochrome c nitrite reductase complex from nitrate-ammonifying bacteria, a multiheme system with novel structural motifs and spectroscopic properties, and (ii) the adenosine-5`-phosphosulfate reductase and the dodecaheme protein from sulfate-reducing bacteria.