Structural Changes Following the Formation of D + Q A - in Bacterial Reaction Centers: Measurement of Light-Induced Electrogenic Events in RCs incorporated in a Phospholipid Monolayer

The primary process of photosynthesis that takes place in the bacterial reaction center (RC) entails a light-induced excitation of a bacteriochlorophyll dimer (D) followed by a sequential transfer of an electron from D to the primary and secondary acceptors QA and QB [reviewed in (1)]. To obtain a large quantum yield the ratio of the forward electron transfer rate to the the recombination rate must be large. In RCs from Rhodobacter sphaeroides this ratio is 102 – 103, making the charge-separation a very efficient process. It has been postulated that a conformational change accompanying charge separation may aid in producing the high ratio of forward to back reaction (2–4).