Electron Phototransfer between Photosynthetic Reaction Centers of the Bacteria Rhodobacter sphaeroides and Semiconductor Mesoporous TiO_2 Films

摘要

Bacterial photosynthetic reaction centers (RCs) from the purple bacteria Rhodobacter sphaeroides are the most well-studied among the other natural bioaccu-mulators of the solar energy from both structural and functional standpoints [1]. They consist of three protein subunits with a total molecular weight of about 70 kDa and contain several low-molecular-weight cofactors of electron transfer. These cofactors are four bacteriochlo-rophyll (BCh) molecules, two of which form the so-called "special pair" of photochemically active pigment (P), and two bacteriopheophytin (BPh) and two ubiquinones (Q_a and Q_b) molecules, which are the primary and secondary electron acceptors. A high quantum yield of the primary charge separation reaction (～100%) and a relatively high stability make these proteins very attractive objects not only for the research into the basic mechanisms of photosynthesis, but also for design of artificial sensor and energy-storage systems. For these purposes, the general principles underlying the function of natural structures are used and devices with RCs integrated into photovoltaic cells as an active element in the photocurrent generation circuit are designed.