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Department of Biochemistry Ph.D. - University of Pittsburgh, 1961
Farewell
Message
"...As the end of my almost 21 year tenure as Chair, first of the Department of Biochemistry, and for the last five years as Chair of the Department of Biochemistry, approaches, I would like to thank everyone in the department including faculty, post-doctoral fellows, technicians, graduate students and staff for making my job often challenging but also interesting and sometimes actually a fun experience. Listening to presentations at research forum, dissertation proposals and defenses gave me a better understanding of the varied research interests in our department. I continue to have pride in the progress that everyone in the department and their major contributions to science. A second source of pride is the recognition that our department has received for our efforts in the teaching of both biochemistry and pharmacology. All of us have worked as a team to receive the praise of both students and others in the administration for our educational efforts. In our third arena, the department is proud of the service that faculty and students render to the University and the larger scientific community. You all become admirable representative of the department and I commend you for your efforts. Next week, I will begin a new chapter of my life as I assume the position of dean of the undergraduate campus of Oman Medical College, located in Muscat, Oman. As Dean, I will be responsible for designing the curriculum, mentoring and managing faculty and interacting with students extensively. Getting to know a large group of faculty and staff will be a challenge, but my experiences as Chair of BMP should provide me with the necessary expertise to cope with all personality types. As you all know, I spent 5 weeks in the spring of both 2005 and 2006 teaching Biochemistry and interacting with the first year medical students in Oman. I enjoyed learning the culture and working with the students and hope to explore in greater depth the culture and geography of Oman. I am looking forward to this new journey in my life, but will always cherish fond memories of everyone in the department with whom I have interacted over the years..." - Diana Beattie Research: Two different research projects are currently underway in my laboratory. In the first project, we are investigating the role of cytochrome b and the iron-sulfur protein (ISP) of the cytochrome bc 1 complex in the electron transfer and proton releasing reactions that occur at the quinol-oxidizing site of the complex. Proton pumping in the bc 1 complexes isolated from yeast mitochondria and the photosynthetic bacterium, R. sphaeroides, is inhibited by the carboxyl-modifying reagent dicyclohexylcarobdiimide (DCCD) that binds covalently to an acidic amino acid localized in extra-membranous, yet hydrophobic, helix cd of cytochrome b connecting the membrane-spanning helixes C and D. Biochemical analyses of yeast cytochrome b mutants in which proton pumping and electron transfer appear to be ‘decoupled’ are proposed to test the suggestion that acidic amino acids in helix cd play a role in proton translocation. Similar studies with site-directed mutants of protonic amino acids present in helix cd of R. sphaeroides are also proposed to test this suggestion. The ISP, in conjunction with cytochrome b, participates in the quinol-oxidizing site as predicted in the Q-cycle mechanism. Site-directed mutagenesis of several amino acids located in an extra-membranous region of the ISP has indicated that a patch of charged amino acid residues is required for efficient assembly of the ISP into the bc 1 complex. Additional site-directed mutants of amino acids located in a putative mobile section of the ISP are also proposed to test whether movement of the ISP is required for enzyme activity. In a second project in the laboratory, we are investigating the electron transport chain of the African parasite, Trypanosoma brucei. Trypanosomes have a dual life cycle in both the bloodstream of the mammalian host and the insect vector. In the mammalian bloodstream, the trypanosomes exist as dividing long slender forms that lack well-developed mitochondria and cyanide-sensitive electron transport. In the insect host, the trypanosomes possess a large single mitochondrion with a cyanide-sensitive electron transfer chain similar to that of other organisms. In recent studies in our laboratory, the presence of a rotenone-sensitive NADH dehydrogenase was detected in a mitochondrial fraction isolated from trypanosomes suggesting the presence of complex I in T. brucei. Complex I was partially purified by sucrose density centrifugation of mitochondria solubilized with dodecyl maltoside. Four polypeptides of the partially purified enzymes were identified as the homologous subunits of complex I by immunoblotting with antibodies against subunits of Paracoccus denitrificans and against synthetic peptides predicted from putative complex I subunit genes. Blue Native polyacrylamide gel electrophoresis of solubilized mitochondria revealed the presence of complex I with a molecular mass of 600 kDa containing a minimum of 11 polypeptides. During the sucrose density gradient centrifugation of trypanosome mitochondria, a fraction containing rotenone-insensitive NADH dehydrogenase activity was observed. From this fraction we have isolated and characterized an alternative NADH dehydrogenase that is rotenone-insensitive. This alternative NADH dehydrogenase is a single polypeptide containing FMN as cofactor localized in the inner mitochondrial membrane facing the matrix. The alternative NADH dehydrogenase, unlike complex I, has the ability to produce superoxide radicals. In ongoing studies, we have recently isolated the gene for the alternative NADH dehydrogenase and will characterize the protein more fully after expression in bacteria. A long-term goal of this project is to determine the role of complex I and the alternative NADH dehydrogenase in the overall metabolism and development of T. brucei. References:
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