Metal Cluster Active Sites in Proteins

具有由二铁中心桥接组成的活性位点的蛋白质 由氧代或羟基组成的新亚类 金属蛋白 这一类包括蛋白质， 生物学中的多种功能--分子氧运输 （血红素），氧活化（甲烷单加氧酶）， 核糖核苷酸向脱氧核糖核苷酸的转化 （核糖核苷酸还原酶）和磷酸酯水解 （紫色酸性磷酸酶）。 该项目将侧重于 后两种酶。 核糖核苷酸还原酶是关键酶 在脱氧核糖核苷酸的生物合成中， 磷酸酶可能参与调节机制， 重要的生物学过程。 对于核糖核苷酸还原酶，Que博士将研究三种 方面：a）二铁形式的光谱性质 以及它如何与分子氧相互作用，B） 酪氨酰自由基的形成及其对簇合物的影响 通过长距离电子转移的簇通信，以及 c）使用冷冻酶技术捕获 二价铁形式与O2反应的中间体 以及这些中间体的光谱表征。 为 紫色酸性磷酸酶，将进行实验， 测试所提出的活性位点模型和所提出的机制 酶的作用。 使用的物理技术包括超 紫，可见光和红外光谱，共振拉曼 光谱，核磁共振，电子顺磁共振，穆斯堡尔谱，磁性圆 二向色性和EXAFS。

Proteins with active sites consisting of di-iron centers bridged by oxo or hydroxo groups comprise a new subclass of metalloproteins. This class includes proteins that perform a variety of functions in biology -- dioxygen transport (hemerythrin), oxygen activation (methane monooxygenase), the conversion of ribonucleotides to deoxyribonucleotide (ribonucleotide reductase), and phosphate ester hydrolysis (purple acid phosphatases). This project will focus on the latter two enzymes. Ribonucleotide reductase is the key enzyme in the biosynthesis of deoxyribonucleotide, while purple acid phosphatase may be involved in the regulatory mechanisms of important biological processes. For ribonucleotide reductase, Dr. Que will investigate three aspects: a) the spectroscopic properties of the diferrous form and how it interacts with dioxygen, b) the stoichiometry of tyrosyl radical formation and its implications of cluster- cluster communication via long range electron transfer, and c) the use of cryoenzymological techniques to trap intermediates in the reaction of the di-ferrous form with O2 and spectroscopic characterization of these intermediates. For purple acid phosphatase, experiments will be carried out to test a proposed active site model and a proposed mechanism of enzyme action. Physical techniques to be used include ultra- violet, visible and infra-red spectroscopy, resonance Raman spectroscopy, NMR, EPR, Mossbauer spectroscopy, magnetic circular dichroism and EXAFS.