Kinetic properties of prompt and delayed fluorescence of chlorophyll a with λmax= nm when electron transport is blocked on acceptor side of photosystem II

1975 ◽  
Vol 7 (4) ◽  
pp. 167-174
Author(s):  
E. M. Sorokin
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Delayed Fluorescence ◽  
Kinetic Properties ◽  
Acceptor Side ◽  
Fluorescence Of Chlorophyll A ◽  
Prompt And Delayed Fluorescence ◽  
Delayed Fluorescence Of Chlorophyll

Picrate Salt of a Cyclic Polyether, 18-Crown-6 (Ca-picrate-18-crown-6), Inhibits the Photosynthetic Electron Transport at the Acceptor Side of Photosystem II

1998 ◽  
Vol 53 (3-4) ◽  
pp. 159-162
Author(s):  
Manoj K. Joshi ◽  
T. S. Desai ◽  
Prasanna Mohanty
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Photosynthetic Electron Transport ◽  
Acceptor Side ◽  
Site Of Action ◽  
Fast Chlorophyll A Fluorescence

Abstract It has been demonstrated that cyclic polyether, K -picrate-18-crown-6 inhibited photosyn­ thetic electron transport (Sabat et al., 1991, Z. Naturforsch. 46c , 87-92) . We further analyzed the alterations induced in the fast chlorophyll a fluorescence and thermoluminescence pattern of pea thylakoids by calcium-18-crown-6 (crown-picrate). The results indicate that the site of action of calcium crown-picrate is at the acceptor side of photosystem II.

Studies about the Mechanism of Herbicidal Interaction with Photosystem II in Isolated Chloroplasts

1979 ◽  
Vol 34 (11) ◽  
pp. 1010-1014 ◽  
Author(s):  
Gernot Renger
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Electron Acceptor ◽  
Functional Organization ◽  
Regulatory Element ◽  
Release Kinetics ◽  
Acceptor Side ◽  
Receptor Sites ◽  
Isolated Chloroplasts

Abstract Based on the functional organization scheme of system-II-electron transport and its modification by different procedures a proteinaceous component enwrapping the redox components (plastoquinone molecules) of the acceptor side (thereby acting as regulatory element) is inferred to be the unique target for herbicidal interaction with system II. This proteinaceous component, which is attacked by trypsin, provides the receptor sites for the herbicides. Studies of the release kinetics in trypsinated chloroplasts of the inhibition of oxygen evolution with K3 [Fe (CN)6] as electron acceptor indicates, that there exists a binding area with different specific subreceptor sites rather than a unique binding site for the various types of inhibitors. Furthermore, trypsination of the proteinaceous component enhances the efficiency of the plastoquinone pool to act as a non-photochemical quencher for excitation energy.

The Inhibition of Photosynthetic Electron Transport by DBMIB and its Restoration by p-Phenylenediamines; Studied by Means of Prompt and Delayed Chlorophyll Fluorescence of Green Algae

1974 ◽  
Vol 29 (11-12) ◽  
pp. 725-732 ◽  
Author(s):  
Robert Bauer ◽  
Mathijs J. G. Wijnands
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Photosystem Ii ◽  
Photosynthetic Electron Transport ◽  
Primary Electron ◽  
Delayed Fluorescence ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Exchange Reactions ◽  
Redox Systems

Abstract The effect of the plastohydroquinone antagonist dibromothym oquinone (DBMIB) on photosynthetic electron transport reactions was studied in the presence and absence of p-phenylene-diamines by means of measurements of prompt and delayed chlorophyll fluorescence induction of the green alga Scenedesm us obliquus. Prompt and delayed chlorophyll fluorescence induction phenomena are valid indicators for the native presence of and cooperation between the two photosynthetic light reactions. Their kinetics reflect the balancing of electron exchange reactions in the chain of coupled redox-systems between the two photosystems upon sudden illumination. From distinct alterations of the short-term (sec) light induced changes in the yield of prom pt and delayed chlorophyll fluorescence it is concluded that DBMIB inhibits the photosynthetic electron transport in the chain of redox-systems between the two light reactions. There is evidence to show that upon illumination of DBMIB treated cells only the reduction of primary electron ac­ceptor pools of photosystem II (i. e. Q and PQ) is still possible. After their reduction the further electron transport through photosystem II is blocked. The addition of p-phenylenediamines to DBM IB-treated cells abolishes the typical DBMIB-affected prom pt and delayed fluorescence inhibition curves and the normal induction curves re­ appear qualitatively in all their important features. From these measurements it is suggested that the redox properties of p-phenylenediamines allow an electron transport bypass of the DBMIB inhibition site which results in a fully restored photosynthetic electron transport from water to NADP.

Interactions of Protons with Transitions of the Watersplitting Enzyme of Photosystem II as Measured by Delayed Fluorescence

1978 ◽  
Vol 33 (3-4) ◽  
pp. 271-275 ◽  
Author(s):  
Jane M. Bowes ◽  
Antony R. Crofts
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Fluorescence Intensity ◽  
Methyl Viologen ◽  
Fluorescence Emission ◽  
Delayed Fluorescence ◽  
Reduced Form ◽  
Maximal Intensity ◽  
Internal Ph ◽  
S States

Abstract By measuring ms delayed fluorescence emission, we have investigated the interaction of protons in the reactions of the watersplitting enzyme of photosystem II.(1) In the presence of the electron transport mediators 2,3,5,6-tetramethyl-p-phenylene diamine (DAD) (in its reduced form) and methyl viologen and of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), the maximal intensity of the delayed fluorescence measured between 1 and 1.5m s after illumination was greater than the level reached in the presence of DCMU alone.(2) The stimulation of the delayed fluorescence was greater when the suspension was preilluminated by 1 - 8 xenon (or laser) flashes prior to addition of DCMU, and the maximal intensity varied with the number of preilluminating flashes given.(3) The amplitude of the intensity of delayed fluorescence oscillated with a periodicity of 4, with a maximum after 2, and minimum after 4 flashes. A negligible oscillation wras observed in the absence of the electron transport mediators.(4) When the prompt fluorescence intensity was measured under these conditions, a weak oscillation of period 4 with superimposed periodicity of 2 was observed in F0, but of insufficient amplitude to account for the observed changes of delayed fluorescence intensity in terms of the bade reaction caused by addition of DCMU.(5) We therefore suggest that the enhancement of the delayed fluorescence is due to the release of protons accompanying transitions of the S-states, and that this release occurs not in synchrony with 02, but in all the transitions of the S-states with the exception of Si → S2 . We discuss the relative potentials of the transitions at the low internal pH which is generated as a result of cyclic electron transport around photosystem I in the conditions of our experiments.

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