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Cytochrome C subunit of the bacterial photosynthetic reaction center Photosynthesis in purple bacteria is dependent on light-induced electron transfer in the reaction center (RC), coupled to the uptake of protons from the cytoplasm. The RC contains a cytochrome molecule which re-reduces the oxidized electron donor. The electron transfer reactions of photosynthesis are performed by the following three components: the photosynthetic reaction center (RC), the cytochrome, and the soluble electron carrier protein. Firstly, the RC promotes the light-induced charge separation across the plasma membrane, which results in the oxidation of a pair of light-harvesting complexes, LH1 and LH2, and the reduction of quinone to quinol. The quinol then leaves the RC and moves to the cytochrome complex through the quinone pool of the plasma membrane. Secondly, the cytochrome complex reoxidizes the quinol to quinone, and the released electrons are transferred to soluble electron carriers. Third, the soluble electron carriers transport the electrons to the RC through the periplasmic space. Finally, the photo-oxidized light-harvesting complex is reduced by the soluble electron carriers, and the RC comes back to the initial state. In the course of the oxidation and reduction of the quinones, a transmembrane electrochemical gradient of protons is formed, and its energy is used to produce ATP by the ATP synthase complex. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",