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Libai Huang
University of Notre Dame
Mapping Primary Electron and Energy Transfer Pathways onto Coordinate Structure in Single Crystals of the Photosynthetic Reaction Center
Monday April 18, 2011
3:30pm PHYS 203
Unless otherwise noted, seminars are held on Mondays at 3:30 p.m. in Physics Room 203. Coffee served at 3:15pm in Phys 244.
High-resolution function mapping of cofactor-specific photochemical functions in photosynthetic reaction centers (RCs) from Rhodobacter sphaeroides was achieved by polarization ultrafast spectroscopy in single crystals at cryogenic temperature. By exploiting the fixed orientation of cofactors within crystals, we were able to isolate a single transition within multi-cofactor manifold and to elucidate the site-specific photochemical functions of the cofactors associate with the active A branch and inactive B branch. Characteristic delocalized excited states were observed to follow localized excitation of cofactors. The delocalized nature of the initial excited states was attributed to electronic mixing and correlated energy levels of the cofactors in RC complexes. Remarkably different photochemical functions were revealed for bacteriochlorophyll cofactors associate with A and B branch. These studies demonstrate the opportunity to exploit the fixed orientation of cofactors within crystals to achieve cofactor-specific, “high-resolution” maps of photosynthetic function within multi-cofactor manifolds.