People: Mass Spectrometrist Achieves Recognition As Virginia's 1992 Outstanding Scientist

Donald Frederick Hunt, a professor of chemistry at the University of Virginia, Charlottesville, has been chosen as the state of Virginia's outstanding scientist of 1992. Hunt was introduced to the state's General Assembly on February 26 and was honored at a March 30 ceremony at the Science Museum of Virginia in Richmond. Also honored were Joseph Larner, a professor of pharmacology at the university's Health Sciences Center, who was given a lifetime achievement award, and William O. Bourke, chairman and CEO of Reynolds Metals Co. of Richmond, who was named the outstanding industrialist of the year. In 1981, Hunt and colleagues pioneered the use of tandem mass spectrometry--an arrangement of two spectrometers in series--to determine the structure of proteins. The protein is first degraded using standard biochemical techniques into a group of peptides, each containing up to 25 or 30 amino acids. Each peptide is placed in the mass spectrometer, where it is broken up via high-energy collision with argon atoms. The pieces that result are then weighed on a millisecond timetable. When the process is applied to all of the fragments, the sequence of the amino acids can be deduced through calculations. Linking two mass spectrometers makes it possible to rapidly weigh pairs of protein fragments differing in length by only one amino acid. Hunt says that his research can lead to an improved understanding of the immune system. When the body becomes infected with a virus, he explains, "fragments, called peptides, of viral proteins are displayed on the surface of the infected cell," along with fragments from normal, or self, proteins. "Cells of the immune system, cytotoxic T- cells, continually monitor the peptides being presented by each cell in the body. If they find only self peptides, the cells are pronounced healthy and ignored. If they find fragments of viral proteins, molecules that perforate the wall of the infected cell are released, and the infected cell is killed. "Somewhere down the line, it may be possible to synthesize the displayed peptides and use them as potential vaccines for diseases like arthritis, AIDS, or hepatitis. There's a tremendous potential, but it's a long way off--not in the near future." Hunt's latest findings, published in two papers in the March 6, 1992, issue of Science (255:1261-63; 255:1264-66), characterize peptides associated with the class I major histocompatibility complex (MHC) molecule, which encodes various components of the immune system. Despite the great utility of mass spectrometry in determining the amino acid sequence of proteins, Hunt says, the technique took a long time to catch on. "Biochemistry people in general have not been impressed with mass spectrometry," he says. Moreover, "among my peers in mass spectrometry," the technique took a long time to gain acceptance because "we operate the instrument in a very unconventional manner." Today, however, the method has grown in popularity; Hunt teaches a course in the technique that attracts biochemists and molecular biologists from all over the world. Currently, Hunt and colleagues are working to develop a new type of mass spectrometer called the ion trap, which he hopes will be 100 times more sensitive than present tandem mass spectrometers. A former graduate student of Hunt's, George Stafford, now at Finnigan MAT Corp. of San Jose, Calif., is creating the instrument, for which Finnigan has the patent. In addition, says Hunt, "we're trying to build an instrument on our own, as well," under the direction of Hunt's longtime collaborator, Jeffrey Shaban-owitz, a senior scientist at Virginia. Hunt received his Ph.D. in 1967 from the University of Massachusetts. He joined the Virginia faculty as an assistant professor in 1968 and was promoted to associate professor and full professor in 1973 and 1978, respectively. --Barbara Spector

People: Mass Spectrometrist Achieves Recognition As Virginia's 1992 Outstanding Scientist

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