Metal Cluster Active Sites in Proteins

9405723 Que蛋白质的活性位点由通过单个氧原子桥和/或羧酸盐连接的二铁中心组成，其包含金属蛋白质的新亚类。这一生长类包括双氧活化酶，如甲烷单加氧酶、核糖核苷酸还原酶和硬脂酰ACP δ 9去饱和酶，以及水解酶，如紫色酸性磷酸酶。 这个建议的一个主要目标是通过比较不同氧化态蛋白质的光谱特性来确定不同蛋白质的二铁位点是如何相互关联的。第二个目标，这是具体的双氧活化酶，是了解氧活化的机制，通过表征瞬态物种中观察到的双氧与这些酶的双铁（II）状态的反应。 第三个目标，这是具体的紫色酸性磷酸酶，是要确定两个金属中心在水解机制中发挥的作用。 这个项目的目的是了解一类新的金属酶如何与活性位点组成的两个铁中心催化代谢重要的反应。例如，甲烷单加氧酶在温和的条件下将甲烷转化为甲醇，这与目前的能源密集型工业过程形成对比。 另一方面，核糖核苷酸还原酶负责在细胞生长期间制造脱氧核糖核苷酸，即DNA的构建单元。 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位点，以了解它们的结构关系，它们如何催化各自的反应，以及各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. ***