ABSTRACT
Harvesting the energy borne by photons not only involves absorbing light quanta but also converting this energy into an electrochemical potential. This relies on electron transfer reactions that trap the excitonic energy and, being coupled to proton transfer, allows the establishment of the proton motive force that drives ATP synthesis. As in all energy-converting systems, the power that can be delivered by the photosynthetic converter depends, on the one hand, on the power that it receives and absorbs and, on the other hand, on its converting efficiency. The latter is determined by the thermodynamic and kinetic properties of the electron transfer reactions between the successive donors and acceptors borne by the different protein complexes that make the photosynthetic chain. The redox potentials of these cofactors are thus key parameters, and we will discuss here how and, when possible, why they are modulated by the protein moiety.
