NOVEL REDOX PROTEINS FROM SULFATE REDUCING BACTERIA

三种新的非血红素铁蛋白已被分离最近从 脱硫弧菌属的硫酸盐还原菌。 它们是：（1） 铁氧还蛋白，含有扭曲的FeS 4中心（中心）的单体 I）和八面体配位的铁中心，其具有含N和O的 配体（中心II），（2）赤藓红蛋白，含有两个 红氧还蛋白样FeS 4中心和一个（可能是两个）μ-氧桥连二铁 簇，和（3）isadoxin（暂以伊莎贝尔莫拉博士命名， 发现这种蛋白质），一种单体，可能含有两个氧化还原活性 未知结构的铁硫簇。 该提案的重点是 这些蛋白质的EPR和穆斯堡尔谱研究， 一个更大的，实验室间的研究计划，旨在阐明 从硫酸盐中分离的金属蛋白的结构和功能 硝酸盐还原菌 本提案的目的是获得 上述铁中心的结构信息， 光谱研究 通过关联这些光谱结果 生物学和生物化学特性将通过我们的 合作者，我们希望获得这些功能信息 有趣的蛋白质 已知某些硫酸盐还原菌是导致 厌氧海洋环境中有机物的降解。 的 催化芳香族化合物厌氧降解的酶， 然而，还没有被发现。因此，有趣的是， 铁氧还蛋白的中心II显示出光谱特性， 类似于双加氧酶的那些。 因此，对于研究 铁氧还蛋白，重点是中心II。 拟议的实验 是专门设计用来探测中心II的配体环境的 并研究其与芳香族有机化合物的相互作用， 小分子配体 对于红菊酯，我们的重点将放在二铁簇上。 现在 意识到mu-oxo桥连的二铁簇参与了 催化多种重要的生物功能，包括 氧传输、甲烷羟基化、苯酚氧化和水解 磷酸酯。 该计划的一个具体目标是 获得详细的光谱表征并探测配体 二铁簇的环境。 结果应 提高我们对物理性质和协调性的认识 这种多功能生物基序的化学性质。 对于艾萨杜辛，我们的目标是获得结构信息， 获得这种罕见铁的详细电子和磁性 集群 我们的初步研究表明，至少有一个（如果不是） 两者）的集群可能是一个6 Fe集群与混合的S，0，和/或N 配体，一种以前从未报道过的独特结构， 既不是蛋白质也不是模型化合物。 因此，结果 从拟议的测量获得的预期刺激新的 铁硫蛋白的研究进展。

Three novel non-heme iron proteins have been isolated recently from sulfate reducing bacteria of the Desulfovibrio genus. They are: (1) desulfoferrodoxin, a monomer containing a distorted FeS4 center (center I) and an octahedrally coordinated iron center with N- and O-containing ligands (center II), (2) rubrerythrin, a dimer containing two rubredoxin-like FeS4 centers and one (may be two) mu-oxo bridged diiron cluster, and (3) isadoxin (tentatively named after Dr. Isabel Moura who discovered this protein), a monomer containing probably two redox active iron-sulfur clusters of unknown structure. This proposal is focused on the EPR and Mossbauer studies of these proteins and is an essential part of a larger, inter-laboratory research program aiming to elucidate the structure and functions of metalloproteins isolated from sulfate and nitrate reducing bacteria. The objective of this proposal is to gain structural information of the above mentioned iron centers through spectroscopic investigations. By correlating these spectroscopic results with the biological and biochemical properties to be obtained by our collaborators, we hope to acquire functional information of these interesting proteins. Certain sulfate reducing bacteria are known to be responsible for the degradation of organic matter in anaerobic marine environment. The enzyme which catalyzes the anaerobic degradation of aromatic compounds, however, has not get been found. It is therefore interesting to note that center II in desulfoferrodoxin exhibits spectroscopic properties similar to those of dioxygenases. Consequently, for the studies of desulfoferrodoxin, emphasis is on center II. The proposed experiments are specifically designed to probe the ligand environment of center II and to investigate its interaction with aromatic organic compounds and small ligands. For rubrerythrin, our focus will be on the diiron cluster. It is now realized that the mu-oxo bridged diiron cluster is involved in the catalysis of a variety of important biological functions, including oxygen transport, methane hydroxylation, phenol oxidation, and hydrolysis of phosphate esters. A specific goal of this proposed program is to obtain detailed spectroscopic characterization and to probe the ligand environment of the diiron cluster in rubrerythrin. The results should enhance our knowledge on the physical properties and coordination chemistry of this versatile biological motif. For isadoxin, our objective is to gain structural information and to obtain detailed electronic and magnetic properties of the unusual iron clusters. Our preliminary studies suggest that at least one (if not both) of the clusters is probably a 6Fe cluster with mixed S, 0, and/or N ligands, a unique structure that has never been reported previously, neither for proteins nor for model compounds. Consequently, results obtained from the proposed measurements are expected to stimulate new developments in the research of iron-sulfur proteins.