Induction Kinetics of Millisecond-Delayed Luminescence in Intact Bryopsis Chloroplasts

The induction curve of delayed luminescence emitted from 0.5to 2.5 ms after excitation of dark-adapted intact chloroplastsof the green alga, Bryopsis maxima, showed three transient peaks,L₁, L₂ and L₃ (in order of appearance), at about 0.1, 1 and5 s after theonset of intermittent illumination. Intact chloroplastswere needed for L₂ to appear, whereas L₁ and L₃ were presentin hypotonically treated chloroplasts. L₁ and L₂ are related to the electric field generated acrossthe thylakoid membranesbecause the two peaks parallelled theappearance of the first and second peaks of electrochromic absorptionchanges at 560 nm and they were totally abolished by valinomycinand CCCP. A smaller contribution to the L₁ and L₂ of the protonactivity gradient across the membranes, or of pH changes insideor outside the membranes, was suggested by the partial suppressionof the transient by NH₄CI. L₃ is related to the proton gradient or pH changes because thetransient was inhibited by NH₄CI and CCCP but enhanced by N,N'-dicyclohexylcarbodiimide.In the presenceof valinomycin, which somewhat lowered the peakheight of L₃, the kinetics of delayed luminescence parallelledthat of fluorescence. Electrogenic reactions which occur sequentiallyduring the dark to light transition of the photosynthetic machineryin intact chloroplasts is discussed in connection with transientchanges in delayed luminescence. (Received November 8, 1982; Accepted May 21, 1983)