Special Issue: Förster Resonance Energy Transfer
Photosynthetic process is powered by several photosyntheticproteins that are located within a membrane. The two photosystems (PS I and PSII) convert energy of absorbed photons into a flow of electrons. Both proteinscontain significant amount of chlorophylls that absorb sunlight and transferelectronic excitation energy to respective reaction centers that are located inthe middle of each complex and that consists of few chlorophyll molecules. Theelectron generated in PS II complex is transferred to the cytochrome 6 complex via plastoquinol pool (PQH2), and then to PS Iby a small protein called plastocyanin (PC). The cytochrome 6 complex couples electron transport to proton translocation acrossthe membrane that serves to build a proton gradient across the membrane. PS IIcaptures its missing electron from water molecule generating free oxygen andprotons, which further rises the proton gradient across the photosyntheticmembrane. The electrochemical gradient generated in this way drives theseprotons through an ATP synthase making this molecular size motor spin. Themechanical energy of that motion is used to force ADP and Pimolecules together creating ATP (adenosine triphosphate) that serves as auniversal energy carrier in living organisms. The electron generated by PS I ispicked up by a small mobile protein – ferredoxin, FD – and is transported toFNR where its energy is used to reduce NADP+ into NADPH.
Resonance energy transfer in proteins; ..
Resonance energy transfer - Biology-Online Dictionary
"Our results suggest that correlated protein environments preserve electronic coherence in photosynthetic complexes and allow the excitation to move coherently in space, enabling highly efficient energy harvesting and trapping in photosynthesis," says Fleming. "Rather than simply serving as a static structure that holds the pigments in the proper geometry for efficient energy transfer to the reaction centers, as was anticipated, we find that the protein environment in the reaction centers plays a dynamic role in optimizing the efficiency of the energy transfer."
Resonant energy transfer - Wikipedia
In the latest results, Fleming and his group have found that in the tightly packed complex formed by pigments and proteins, the light-induced energy excitations in the pigment molecules also set off the vibrational modes of the proteins. This creates a resonance that enhances energy transfer efficiency and is responsible for the long lifetime of the electronic coherence.