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1984 (1)
1Author    ElenaA. Kotova, MarinaD. Il 'inaRequires cookie*
 Title    Effect of Electron Transfer Inhibitors and Uncoupling Agents on the Chlorophyll Fluorescence Lifetime during Slow Fluorescence D ecline in Bean Leaves and Intact Chloroplasts  
 Abstract    Fluorescence m easurem ents were performed with bean leaves and intact chloroplasts, which are characterized by a slow fluorescence decline. The fluorescence lifetime (r) ana the fluores­ cence relative quantum yield (q>) o f intact chloroplasts, measured with the phase fluorometer, showed nearly proportional light-induced decrease with a halftime o f ~ 3 0 s, which was removed by 3-(3.4-dichlorophe n y l)-1.1 -dimethylurea (DC M U), by 4.5,6,7-tetrachloro-2'-trifluoromethyl-benzimidazole (TTFB). by carbonyl cyanide /?-trifluoromethoxyphenylhydrazone (FCCP) at a low concentration and by gramicidin D. Simultaneously the slow light-induced increase in absorbance at 518 nm (A A 518), reflecting thylakoid membrane energization, was elim inated. The data on r o f intact chloroplasts are original, the other results agree with literature data. In leaves, the slow light-induced fluorescence decline, with r dropping from ~ 2 to ~ 0.6 ns, was abolished by FCCP at a concentration o f 5 ^m. However, while r was stabilized at a level close to the initial (maximum) one or som ewhat higher, q> became close to the minimum value. Besides, the amplitude o f A A 518 was lowered about three times. These effects seemed to be due to multiple action o f FCCP as a protonophoric uncoupler and an electron transfer inhibitor. In the presence o f another uncoupling agent, TTFB, which, besides, is a diuron-like inhibitor o f the electron transfer in chloroplasts, we observed the light-dependent, but hardly linked to changes in membrane potential, great increase in r o f a leaf from ~ 1.9 to ~ 4 .3 ns, with cp decreasing slightly. Addition o f DC M U together with FCCP to the incubation medium or infiltration o f a leaf with DCM U alone stimulated the rise in r only to ~ 3 ns. The increase in r o f a leaf observed in the presence o f FCCP and DCM U, and especially with TTFB, may be associated with protein conformation changes which (i) alter the lifetime o f nanosecond recombination lum inescence o f the photosystem II a n d /o r (ii) disturb excitation energy transfer from the light-harvesting chlorophyll a /b com plex to other pigment-protein complexes. 
  Reference    Z. Naturforsch. 39c, 93—101 (1984); received October 5 1983 
  Published    1984 
  Keywords    Photosynthesis, C hlorophyll Fluorescence Lifetime, Electron Transfer Inhibitors, Uncouplers, Bean Leaves, Intact Chloroplast 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0093.pdf 
 Identifier    ZNC-1984-39c-0093 
 Volume    39