Induction Kinetics of Millisecond-Delayed Luminescence in Intact Bryopsis Chloroplasts

概要

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he induction curve of delayed luminescence emitted from 0.5 to 2.5 ms after excitation of dark-adapted intact chloroplasts of the green alga, Bryopsis maxima, showed three transient peaks, L_1, L_2 and L_3 (in order of appearance), at about 0.1, 1 and 5 s after the onset of intermittent illumination. Intact chloroplasts were needed for L_2 to appear, whereas L_1 and L_3 were present in hypotonically treated chloroplasts. L_1 and L_2 are related to the electric field generated across the thylakoid membranes because the two peaks parallelled the appearance of the first and second peaks of electrochromic absorption changes at 560 nm and they were totally abolished by valinomycin and CCCP. A smaller contribution to the L_1 and L_2 of the proton activity gradient across the membranes, or of pH changes inside or outside the membranes, was suggested by the partial suppression of the transient by NH_4Cl. L_3 is related to the proton gradient or pH changes because the transient was inhibited by NH_4Cl and CCCP but enhanced by N,N'-dicyclohexylcarbodiimide. In the presence of valinomycin, which somewhat lowered the peak height of L_3, the kinetics of delayed luminescence parallelled that of fluorescence. Electrogenic reactions which occur sequentially during the dark to light transition of the photosynthetic machinery in intact chloroplasts is discussed in connection with transient changes in delayed luminescence.
日本植物生理学会の論文