Wednesday, March 17, 2010
Graduate Students Receive Astrid and Bruce McWilliams Fellowships
Graduate students Tristan Bereau and Rupal Gupta have been awarded Astrid and Bruce McWilliams Fellowships in the Mellon College of Science in recognition of their outstanding creativity, dedication and commitment to carrying out leading-edge research.
“Thanks to the McWilliams’ extraordinary support, we are able to foster the early careers of two outstanding PhD students,” said Fred Gilman, dean of the Mellon College of Science and Buhl Professor of Theoretical Physics. “Tristan and Rupal are independent and creative young researchers who have already published their work in top journals in their fields by making multidisciplinary advances in biology, chemistry, and physics.”
Tristan Bereau, a fourth year Ph.D. student in the Department of Physics, is developing a coarse-grained computer model to simulate the behavior of proteins as they interact with lipids in the cell membrane. Creating a coarse-grained model, which replaces a few atoms with one bigger quasi-atom or “bead,” enables Bereau to observe protein behavior at longer time and length scales. Doing so is key to studying the mechanisms involved in the development of Alzheimer’s disease, including how cell membranes are affected by the protein amyloid-ß. Small aggregates of amyloid-ß are suspected to substantially contribute to the devastating neurodegenerative pathologies leading to Alzheimer’s disease, but investigating experimentally how amyloid-ß causes damage is extremely difficult. By combining his computer model of proteins with a model of the cell membrane, Bereau will be able to simulate how amyloid-β interacts with the cell membrane. The paper describing Bereau’s computer model was among the most-downloaded papers in the Journal of Chemical Physics the month it was published.
“In the past two years Tristan has produced an amazing body of scientific results, many of them originating entirely from his own ideas,” said Markus Deserno, associate professor of physics and Bereau’s research advisor. “He is an extremely talented student who has an excellent taste for what’s important.”
Rupal Gupta, a fourth year Ph.D. student in the Department of Chemistry, uses spectroscopy to understand the function of enzymes and proteins, especially those that contain metal atoms. For the past three years, Gupta has focused her efforts on trytophan dioxygenase (TDO), an iron-containing enzyme that breaks down tryptophan, an essential amino acid. TDO degrades trytophan so that it can be used as a building block for several molecules, including NAD, which is central to cells’ energy production, and serotonin, a brain chemical linked to depression. TDO is similar to hemoglobin in that both molecules are made up of four protein subunits, each containing an iron atom. But, unlike hemoglobin’s structure and activity, which have been well characterized, the intricacies of TDO activity and its mechanisms are unknown. Using Electron Paramagnetic Resonance (EPR) and Mössbauer spectroscopies, Gupta probed the spin states of the iron atoms in TDO. From this information she determined that the iron groups contained in the protein’s four subunits are different and occur in pairs. Previous studies suggested that the enzyme’s four active sites were the same. Gupta recently published her findings in the Journal of the American Chemical Society.
“Rupal has a strong grasp of physical chemistry, and an in-depth understanding of spin physics, which is rare in a graduate student,” said Chemistry Professor Michael Hendrich, Gupta’s research advisor. “She is a bright, outstanding and promising young scientist.”
The Astrid and Bruce McWilliams Fellowship in the Mellon College of Science was established in 2007 by alumnus Bruce McWilliams, chairman of Tessera Technologies’ board of directors, the company’s chief strategy officer and a Carnegie Mellon University trustee; and his wife, Astrid McWilliams, to support graduate students conducting leading-edge research in emerging fields such as nanotechnology, biophysics and cosmology. It provides tuition, stipend and fees for up to one year of graduate study, as well as $1000 for conference travel or other research expenses.