Fluorescence Decaying Kinetics and Photodamage of Quinone-Reconstituted D1/D2/Cytochrome b559 Complex

Photosystem Ⅱ reaction center D1/D2/Cytochrome b559 complex loses its bound secondary electron acceptor QA and QB during isolation and purification. The artificial plastoquinone can reconstitute with the complex. The reconstitution of decyl-plastoquinone (DPQ) with D1/D2/Cytochrome b559 complex results in a decrease of the fraction of the two long lived fluorescence decay components (24 ns and 73 ns) coupled with photochemical activities to the total fluorescence yields, as well as a decrease of the total fluorescence intensity and a blue-shift of maximum emission wavelength. These results suggest that as the electron acceptor of reduced Pheo, DPQ restricts the charge recombination of P680+ Pheo-, and the two long lived fluorescence decay components (24 ns and 73 ns) come from the recombination. Although DPQ reconstitution has little effect on the susceptibility of Chi a to photodamage, β-carotene can easily be photodamaged after DPQ reconstitution. This is probably related to the physiological function of β-carotene.