Metal Cluster Active Sites in Proteins

9405723个Que蛋白的活性中心由单个氧原子桥和/或羧基连接的双铁中心组成，构成了一个新的金属蛋白亚类。这一不断增长的类别包括氧激活酶，如甲烷单加氧酶、核苷酸还原酶和硬脂酰ACP Delta9脱饱和酶，以及水解酶，如紫色酸性磷酸酶。这项提议的一个主要目标是通过比较不同氧化态的光谱性质来确定不同蛋白质的双铁位置是如何相互关联的。第二个目标是通过表征在氧气与这些酶的二铁(II)状态反应中观察到的瞬时物种来了解氧激活的机制，这是氧气激活酶所特有的。第三个目标是确定这两个金属中心在水解机制中所起的作用，这是紫色酸性磷酸酶所特有的。这个项目旨在了解一类具有两个铁中心的活性中心的新型金属酶如何催化代谢上重要的反应。例如，甲烷单加氧酶在温和的条件下将甲烷转化为甲醇，这与目前能源密集型工业过程形成了鲜明对比。另一方面，核糖核苷酸还原酶负责在细胞生长过程中合成脱氧核糖核苷酸，这是DNA的组成部分。使用各种光谱方法作为探针，我们将比较这些酶的各种形式的活性部位，以了解它们的结构关系，它们如何催化各自的反应，以及单个金属中心在进行反应中的作用。***

9405723 Que Proteins with active sites consisting of diiron centers connected by a single oxygen atom bridge and/or carboxylates comprise a new subclass of metalloproteins. This growing class includes dioxygen activating enzymes such as methane monooxygenase, ribonucleotide reductase, and stearoyl ACP delta9 desaturase, and hydrolytic enzymes such as the purple acid phosphatases. A major goal of this proposal is to determine how the diiron sites of the different proteins are interrelated by comparing their spectroscopic properties in the various oxidation states. A second goal, which is specific for the dioxygen activating enzymes, is to understand the mechanisms of oxygen activation by characterizing transient species observed in the reaction of dioxygen with the diiron(II) states of these enzymes. A third goal, which is specific for the purple acid phosphatases, is to determine the roles the two metal centers play in the hydrolytic mechanism. %%% This project is aimed at understanding how a new class of metalloenzymes with active sites consisting of two iron centers catalyzes metabolically important reactions. For example, methane monooxygenase converts methane to methanol under mild conditions, in contrast to the current energy-intensive industrial process. On the other hand, ribonucleotide reductase is responsible for making deoxyribonucleotides, the building blocks of DNA, during cell growth. Using a variety of spectroscopic methods as probes, we will compare the active sites of these enzymes in their various forms to understand their structural relationship, how they catalyze their respective reactions, and the roles of the individual metal centers in carrying out the reactions. ***