A Photoinduced Persistent Structural Transformation of the Special Pair of a Bacterial Reaction Center

See allHide authors and affiliations

Science  02 Apr 1993:
Vol. 260, Issue 5104, pp. 68-71
DOI: 10.1126/science.260.5104.68


Structural modification of photosynthetic reaction centers is an important approach for understanding their charge-separation processes. An unprecedented persistent structural transformation of the special pair (dimer) of bacteriochlorophyll molecules can be produced by light absorption alone. The nonphotochemical hole-burned spectra for the reaction center of Rhodopseudomonas viridis show that the phototransformation leads to a red shift of 150 wave numbers for the special pair's lowest energy absorption band, P960, and a comparable blue shift for a state at 850 nanometers, which can now be definitively assigned as being most closely associated with the upper dimer component. Additional insights on excited-state electronic structure include the identification of a new state.