9th Annual Stauffer Lectureship (Day 2 of 2): Professor Harry B. Gray
About the Seminar:
"The Currents of Life: Electron Flow Through Iron and Copper Proteins"
Electron transfers in photosynthesis and respiration commonly occur between metal-containing cofactors that are separated by large molecular distances. Work in our laboratory has shown that chemical bonds can provide a guidance system for these and other biological redox reactions: the rates of electron tunneling over 10 to 30 angstrongs in Ru-modified iron and copper proteins confirm that distant couplings in folded polypeptides are mediated by sigma and hydrogen bonds. Redox equivalents can be transferred even longer distances by multistep tunneling, often called hopping: to investigate the requirements for productive hopping, we have developed methods to generate amino acid radicals through which electrons can tunnel in Re-modified copper proteins.
About the Speaker:
Harry Barkus Gray is the Arnold O. Beckman Professor of Chemistry and the Founding Director of the Beckman Institute at the California Institute of Technology. Gray began his work in organic chemistry at Northwestern University, where he earned a Ph.D. in 1960. After a postdoctoral year at the University of Copenhagen, he joined the chemistry faculty at Columbia University, where his main interests centered on the electronic structures and reactions of inorganic complexes. In the years 1958-64, he worked on ligand substitution mechanisms, establishing fundamental principles that were published in a book with C.H. Langford in 1966. During this same period, he employed molecular orbital theory to describe the electronic structures of transition metal complexes. He elucidated the bonding and reactivity of high-valent metal-oxo complexes, and was among the first to interpret the spectra of low-valent metals with carbon monoxide and nitric oxide. After moving to Caltech in 1966, he and coworkers investigated the solar photochemistry of metal complexes, including the construction of donor-acceptor systems that mimic the early events of photosynthesis. He also attacked the problem of electron flow thorugh biological molecules by examining the kinetics of reactions of iron and copper proteins with inorganic complexes. Working with Ru-modified cytochrome c, he and coworkers discovered in 1982 that electrons can tunnel rapidly over long molecular distances through folded polypeptide structures. In the years following that discovery, he and J.R. Winkler have developed laser-photochemical methods to investigate the free energy and distance dependences of electron tunneling through proteins and other biological molecules; and they have also mapped the folindg energy landscapes of several helical heme proteins. Very recently, Gray and coworkers have constructed photoactive electron tunneling wires to probe deeply buried active sites in P450s and other redox enzymes.
Gray has received the National Medal of Science from President Ronald Reagan (1986); the Bailar Medal (1984); the Centenary Medal (1985); the Pauling Medal (1986); the Linderstrom-Lang prize (Copenhagen, 1991); the Basolo Medal (1994); the Gibbs Medal (1994); the Chandler Medal (1999); the Harvey Prize (Haifa, 2000); the Nichols Medal (2003); six national awards from the American Chemical Society, including the Priestly Medal (1991); and honorary doctorates from Northwestern, Chicago, Rochester, Florence, Goteborg, Columbia, Pennsylvania, and several other universities. He is a member of the National Academy of Sciences; the American Academy of Arts and Sciences; the American Philosophical Society; a foreign member of the Royal Danish Academy of Sciences and Letters; the Royal Swedish Academy of Sciences; and the Royal Society of Great Britain. He was California Scientist of the Year in 1988. During 1997-98, he was the George Eastman Professor at the University of Oxford.