Almlöf-Gropen lecture 2012: Electron flow through metalloproteins
Prof. Harry B.Gray, California Institute of Technology
The Almløf-Gropen Lecturer of 2012 is Professor Harry B. Gray, Arnold O. Beckman Professor of Chemistry and Founding Director of the Beckman Institute, California Institute of Technology, USA. He has published more than 730 papers as well as 17 books, and received a number of international distinctions, including honorary doctorates from the University of Gothenburg and Copenhagen.
Electron transfers in photosynthesis and respiration commonly occur between metal-containing cofactors that are separated by large molecular distances. Understanding the underlying physics and chemistry of these biological electron transfer processes is the goal of much of the work in my laboratory. Employing laser flash-quench triggering methods, we have shown that 2-nm, coupling-limited Fe(II) to Ru(III) and Cu(I) to Ru(III) electron tunneling in Ru-modified cytochromes and blue copper proteins can occur on the microsecond timescale both in solutions and crystals. Redox equivalents can be transferred even longer distances by multistep tunneling (hopping) through intervening tyrosines and tryptophans. In recent work, we have found that 2- to 3-nm hole hopping through one or more intervening tryptophans is several orders of magnitude faster than single-step tunneling in Re-modified mutants of Pseudomonas aeruginosa azurin. The lessons we have learned about the control of electron tunneling and hopping are now guiding the design and construction of sensitizer-modified redox metalloenzymes and other molecular machines for the production of fuels and oxygenated hydrocarbons from sunlight and water.