Profs. Dewey Holten and Christine Kirmaier
Department of Chemistry
Washington University
St. Louis, MO

Monday, April 8, 2013
3:00 pm (CT)
3269 Beckman Institute

Abstract

The first part of the presentation concerns the primary photochemical steps in the energy conversion process in photosynthesis, which occur in pigment-protein complexes called reaction centers (RCs). In the bacterial RC, the membrane-spanning multi-step charge separation process utilizes only one of two parallel electron-transport chains (the so- A side). Studies of mutant RCs using several different motifs that give B-side charge separation, including with yields up to ~70%, will be described. The combined studies are probing the origins of directionality in the bacterial RCs, including the relative contributions of electronic and energetic factors. The second part of the presentation concerns the development and characterization of biohybrid light-harvesting complexes. These systems combine native or close analogs of the peptides from bacterial photosynthetic antenna complexes, native bacteriochlorophyll a, and wavelength-tunable bioconjugatable synthetic bacteriochlorins. Such systems enhance coverage of the solar spectrum compared to native antenna complexes and can give near-quantitative quantum yields of transfer of the harvested photon energy to the target site.