Redesigned Protein-Protein Interface Yields Fastest Recorded Electron Transfer Rate
December 22, 2010 :: Professor Michael R. Wasielewski and researchers at the Argonne-Northwestern Solar Research (ANSER) Center, a DOE Energy Frontier Research Center, in collaboration with Professor Brian M. Hoffman of Northwestern University have designed a protein-protein complex with the fastest recorded interprotein electron transfer rate constant (4.3 x1010 s-1). Brownian dynamics simulations predicted that substituting three surface acid residues in myoglobin (Mb) with lysine binds cytochrome b5 (b5) strongly in an ensemble of bound configurations. Femtosecond transient absorption measurements of the redesigned protein-protein interface led to a range of ultrafast electron transfer rates (109 to 1010 s-1) that approach those occurring within natural photosynthetic reaction centers (photosystem I and photosystem II, 1011 to 1012 s-1). In contrast, most biological interprotein electron transfer processes are typically many orders of magnitude slower (106 s-1). This work demonstrates that efficient photodriven charge transfer can take place between complex, self-assembled structures and holds promise for achieving such behavior in systems designed for artificial photosynthesis. These results were reported in Science and highlighted in Chemical and Engineering News.
