EPR STUDIES OF DINUCLEAR METAL CLUSTERS IN PROTEINS

含有双核金属簇的蛋白质对于许多基本的生命过程是必不可少的，包括DNA合成、氧化磷酸化、甲烷氧化、脂肪酸降解、过氧化物解毒以及氧和电子传递。此外，据信催化自切割反应的核酸酶核酶在活性位点处含有双核金属簇。双核金属簇合物的光谱研究有助于我们在原子水平上理解这些酶和蛋白质的功能。我们已经开发了新的光谱仪器和定量方法，特别适合于探测这些金属簇。EPR光谱一直是研究在许多蛋白质的活性中心中发现的过渡金属离子的有价值的工具。许多具有生物学重要性的金属，如钒、铬、锰、铁、钴、镍、铜和钼，都具有未成对电子，这些电子会产生新的电子自旋和由此产生的磁矩。EPR光谱能够测量这一时刻，因此为这些蛋白质的活性位点提供了显微探针。多年来，EPR光谱一直局限于研究金属蛋白质中具有奇数个未成对电子的金属。然而，我们在过去几年中的工作显着扩大了EPR光谱的应用范围，包括定量分析金属蛋白质与偶数的未成对电子。特别地，具有主要生物学重要性的双核金属簇合物的氧化态是主要具有偶数个电子的状态。

Proteins which contain dinuclear metal clusters are essential for many basic processes of life, including DNA synthesis, oxidative phosphorylation, methane oxidation, fatty acid degradation, peroxide detoxification, and oxygen and electron transport. In addition, the nucleic enzyme ribozyme, which catalyses a self cleavage reaction, is believed to contain a dinuclear metal cluster at the active site. Spectroscopic studies of dinuclear metal cluster contribute to our understanding of the function of these enzymes and proteins at an atomic level. We have developed new spectroscopic instrumentation and quantitative methodologies specifically suited to probe these metal cluster. EPR spectroscopy has long been a valuable tool for the study of the transition-metal ions that are found in the active centers of many proteins. Many metals of biological importance such as vanadium, chromium, manganese, iron, cobalt,, nickel, copper, and molybdenum, have unpaired electrons that give rise to a new electronic spin and a resultant magnetic moment. EPR spectroscopy is capable of measuring this moment and therefore provides a microscopic probe for the active sites of these proteins. For many years, EPR spectroscopy has been limited to studies of metalloproteins have an odd number of unpaired electrons in at the metal. However, our work over the past years has significantly broadened the range of applications for EPR spectroscopy to include quantitative analysis of metalloproteins with an even number of unpaired electrons. In particular, the oxidation states of dinuclear metal clusters that are of main biological importance, are states that predominantly have an even number of electrons.