Obituary of David L. Weaver

David Weaver, a biophysicist who made significant contributions in understanding protein folding, died on April 4, 2006 at his home in Lexington, MA.

David was born in 1937. He had a happy childhood growing up in Albany, NY. At an early age he learned he was a gifted athlete, playing baseball as a star pitcher of his team. His fondest childhood memories were walking the fields behind his home with his dog, and reading for hours sitting on his front porch. He completed a degree in chemistry from Rensselaer Polytechnic Institute in 1958 and went on to Iowa State University where he received a Ph. D. in 1963 as a student of A.F. Voigt and C.L. Hammer, specializing in theoretical particle physics. David joined the Tufts University Physics Department as an assistant professor in 1964, received tenure in 1969, and was promoted to the position of professor in 1977. He continued to serve Tufts as an active faculty member until his untimely death.

At the time of his appointment, experimentalists at Tufts were measuring the production of mesons by polarized gamma rays. David helped them analyze their data, leading to the publication of several papers in which he calculated the spin correlations to be expected in the photoproduction of different spin mesons. David spent the year 1965-66 as a NATO fellow at CERN where he studied the general theory of photoproduction. Over the next few years he published a series of papers with F.A. Berends and with A. Donnachie describing photoproduction in terms of multipole amplitudes constrained to satisfy the dispersion relations of the Mandelstam representation of S-matrix theory. It was in his year at CERN that David met Elena, who was to become his wife. Elena and their three sons, Christopher, Timothy, and Ash, played a very important role in his life.

David changed the direction of his research in 1972. He wanted to apply his physics background to problems in biology that he found intriguing. David accomplished this switch in a very short time, aided by a leave spent working with Martin Karplus in the Chemistry Department at Harvard. The mechanism by which polypeptide chains fold to their unique native state was then a key unsolved problem in biology. After Martin outlined his thinking about the problem, David used his analytical skills to develop what came to be known as the diffusion-collision model of protein folding, first published in Nature in 1976. The model is a coarse-grained description of the folding process, but it showed how the search problem for the native state could be solved by a divide and conquer approach. With the simplifications provided by the model, folding rates could be related to physical parameters for the first time. During the remainder of his career David worked with a series of graduate students, while continuing his collaboration with Martin Karplus, to develop improved protein folding calculations. The diffusion-collision model was ahead of its time because the data needed to test it were not available when it was published in 1976. But by the mid-1990s experimental studies had shown that the model does indeed describe the folding mechanism of many simple proteins. In his work this year David was applying the model to the folding of four-helix bundle proteins and to forms of ribosomal S6.

David served as chair of the Tufts University Department of Physics and Astronomy from 1989 to 2002. In his dealings with the department he was fair to all, striving always to do what he thought was right and equitable. David always possessed an easy manner, a sense of fairness, curiosity and an enjoyment of life that were evident in his teaching and relations with his colleagues.

Two years ago David suffered a stroke that left him with weakness on his right side, but did not affect his speech. He worked hard on his rehabilitation, was able to return to teaching on a part-time basis within a few months, and returned to full-time teaching and research in the following semester. David was planning to spend a sabbatical next year in California, working on protein folding at the UC Davis Genome Center. After this leave, he intended to return to Tufts as an emeritus research professor to work with his two graduate students on the completion of their thesis projects. Sadly David’s energetic and optimistic plans were terminated by his sudden and unexpected death. His kind and cheerful manner and his generous spirit are missed by all who knew him.