Durham, Bill - University of Arkansas-Fayetteville

个人简介

Ph.D., Wayne State University, 1977 Postdoctoral Fellow, University of North Carolina, 1978-79

研究领域

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electron transfer reactions Biological electron transfer reactions play an essential role in numerous important biological processes, including energy production in mitochondrial respiration and the synthesis of numerous cellular materials. Genetic defects in electron transfer proteins are responsible for a variety of human health problems. The long range goals of our research program is to develop a detailed understanding of the features which govern these reactions. Our research program is generally directed toward an understanding of the parameters which govern chemical reactivity. In other words we spend a lot of time studying the rates of chemical reactions. From this information we try to discover what properties of the reactants influence how fast the products are formed. In recent years this interest has lead us into an area which involves a blend of inorganic and biochemistry and collaborations with Frank Millett of this department and several other research laboratories across the country. Our research program focuses on the reactions of metalloproteins which are important in biologically relevant reactions. Many of these reactions appear deceptively simple since only a single electron is transferred from one metal to another. No bonds are broken and there is usually very little change in the structures of reactants. Interesting questions, however, soon become apparent. For example, how does an electron get from one metal center to another if the centers are separated by 10 or 20 Å of protein and solvent? When dealing with proteins in cells there are also questions about how proteins recognize the proper electron acceptors and donors and how the flow of electrons are regulated and ultimately used in energy production of a cell. One particularly fascinating aspect of these electron transfer reactions is the surprisingly high rates at which they take place. In fact, many of the reactions studied to date are much too fast to measure by even the fastest rapid mixing techniques and direct measurements of the electron transfer process are not available. In response to this problem, we have developed a means of measuring the rates of electron transfer which allows us to investigate reactions which are complete within a few nanoseconds or several seconds. We do this by covalently attaching a relatively small ruthenium complex [Ru (bipyridine)3]2+ to one of the proteins and initiating the electron transfer process with a very short short laser pulse. In this sequence of reactions the excited state of the ruthenium complex reduces the protein to which it is attached and the reduced protein is then able to transfer an electron to an appropriate protein acceptor. An added benefit is realized with this technique since the process of transferring electrons from the ruthenium complex also provides an excellent means of investigating electron transfer. We have looked at a variety of metalloproteins with this technique including the reactions of cytochrome c with cytochrome c oxidase, cytochrome c peroxidase, cytochrome b5, cytochrome c1 and plastocyanin.