KINETICS OF PROTON UPTAKE DURING PHOTOCYCLE OF REACTION CENTER OF PHOTOSYNTHETIC BACTERIA

摘要

The reaction center (RC) protein of bacterial photosynthesis catalyses the separation and simultaneous production of oxidizing and reducing equivalents in expense of absorbed light energy. It makes one-electron chemistry at the donor (D) side: D —>D~+ + e~- and two-electron chemistry at the quinone (Q) acceptor side: Q + 2e~- + 2H~+-->QH_2. The products dissociate the RC and new reactants bind to the enzyme from the external (quinone and donor) Pools (Okamura et al 2000, Wraight 2004). In case of large pools, the photocycle runs at constant rate determined by the light intensity and/or by the exchange rates of the donor (D/D~+) and acceptor (Q/QH_2) sides (Osvath & Maroti 1997). The quinone reduction cycle slows down and finally stops when one of the pools is depleted.