Possible role of protein in photosynthetic electron transfer

Photosynthetic electron transfer is discussed from a theoretical viewpoint. Theoretical description of electron transfer including the effect of low-frequency mode of protein is first discussed briefly. Then typical electron transfers in the primary photosynthesis are discussed as examples for the comparison between the theory and experiments. Attention is focussed on the fact that the photosynthetic system organizes a variety of electron transfers in a systematic manner to achieve a vary efficient energy conversion, and it is suggested that the protein environment plays an important role in controlling the rate of electron transfer and maximizing the efficiency of the primary reaction. We emphasize that not only the electronic but also vibrational interactions are important for the regulation of electron transfer. Some novel processes such as activationless and negative activation transfers are shown to be connected with the significance of vibrational factor.