Photoinhibition: Impairment of the primary charge separation between P‐680 and pheophytin in photosystem II of chloroplasts

[摘要]

The question of the primary site of photoinhibition was investigated using the light-induced absorbance change of pheophytin a (at 685 nm) in spinach chloroplasts and Chlamydomonas reinhardtii cells. Photoinhibition of spinach thylakoid membranes resulted in a parallel decrease in the amplitude of the pheophytin a (ΔA ₆₈₅) and Q_A (ΔA ₃₂₀) photoreduction signals. In intact Chlamydomonas reinhardtii cells the pheophytin photoreduction and oxygen evolution activity exhibited a similar decrease during photoinhibition. A complete recovery of both activities was attained within 60 min incubation in normal growth conditions. It is concluded that the primary site of photoinhibition involves the components (P-680 and/or pheophytin) of the primary charge separation.

[学科分类] 生物化学/生物物理

[关键词] Photoinhibition;Charge separation;Pheophytin;Electron transport;(Spinach chloroplast;Chlamydomonas reinhardtii);Chl;chlorophyll;PS;photosystem;QA;primary quinone acceptor of PS II;Pheo;pheophytin primary electron acceptor of PS II;P-680;photochemical reaction center of PS II;C f;flattening correction factor