Pressure Dependence of Energy and Electron transfer in Photosynthetic Complexes

Abstract

Effect of high pressure on the primary charge separation kinetics of the PS II RC has been investigated using spectral hole burning. These results show that pressure has a pronounced effect on primary electron transfer. This effect is plastic (irreversible) in nature in contrast with the elastic effects of pressure on the low temperature Qy- absorption and non-line narrowed hole spectra of P680. The electron-phonon coupling shows only a weak dependence on pressure. Based on these data and using the theory of hole profiles, the energy of the acceptor state in the primary charge transfer is proposed to have pressure shift rate of 1.0 cm-1/MPa. In Rb. sphaeroides LH II antenna complex, the pressure dependence of the B800 and B850 bands as well as the B800→B850 energy transfer rate have been measured. A possible explanation for the pressure independence of the energy transfer rate is provided.