Inhibitors of Photosynthetic Electron Transport. The Properties of Diazidodialkylbenzoquinones

1979 ◽  
Vol 34 (5-6) ◽  
pp. 490-492 ◽  
Author(s):  
Hagan Bayley
Keyword(s):  
Electron Transport ◽  
Membrane Proteins ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Spinach Chloroplasts ◽  
High Concentrations

Abstract The potential photoaffinity reagents 2,5-diazido-3-methyl-6-isopropyl-1,4-benzoquinone (DAZMIB) and 2,5-diazido-3,6-dimethyl-1,4-benzoquinone (DAZDMQ), which are analogs of the well-known inhibitor 2,5-dibromo-3-methyl-6-isopropyl-1,4-benzoquinone (DBMIB), block photosynthetic electron transport in spinach chloroplasts. On irradiation, at relatively high concentrations, DAZMIB inhibits electron flow irrevers­ibly. However, when [3H] DAZDMQ was photolyzed with chloroplasts, no labeling of the membrane proteins was ob­ served. Rearrangements of the nitrenes derived from the oxidized or reduced azidoquinones that might account for this behaviour are discussed.

Mode of Inhibition of Photosynthetic Electron Transport by Substituted Diphenylethers

1981 ◽  
Vol 36 (9-10) ◽  
pp. 848-852 ◽  
Author(s):  
W. Draber ◽  
H. J. Knops ◽  
A. Trebst
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Thylakoid Membranes ◽  
Photosynthetic Electron Flow ◽  
Spinach Chloroplasts

Abstract Several substituted diphenylethers were found to be effective inhibitors of photosynthetic electron flow in isolated thylakoid membranes from spinach chloroplasts. T heir site of inhibition was localized with artificial acceptor and donor systems. The phenylether of an alkyl substituted nitrophenol is prim arely inhibiting electron flow after plastoquinone function whereas a dinitro-phenylether of a phenyl substituted nitrophenol is inhibiting before plastoquinone function. Therefore certain diphenylethers interfere with plastoquinone function at the oxidation or reduction site, depending on the substitution.

Die Wirkung 2.3-substituierter Naphthochinone auf einzellige Algen und isolierte Spinatchloroplasten/ The Effect of 2,3-Substituted Naphthoquinones on Unicellular Algae and Isolated Spinach Chloroplasts

1979 ◽  
Vol 34 (11) ◽  
pp. 961-963 ◽  
Author(s):  
Klaus Bauer ◽  
Helmu Kodier
Keyword(s):  
Electron Transport ◽  
Dark Respiration ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Flow Mode ◽  
Ps Ii ◽  
Spinach Chloroplasts ◽  
Ps I ◽  
Low Concentrations ◽  
Strong Stimulation

Abstract Short term effects of 2-(C-dichloro-acetylamino)-3-chloro-1,4-naphthoquinone (Hoe 13465, quinonamid*) and 2-amino-3-chloro-1,4-naphthoquinone (Hoe 17399, 06K-quinone) on cell suspensions of Chlorella vulgaris, Anabaena flos aquae, Porphyridium cruentum, and on isolated spinach chloroplasts were studied. The results clearly show that both substances inhibit the photosynthetic O2 production of algal suspensions as well as the electron transport of PS II in spinach chloroplasts. PS I is not inhibited by the action of the two algicides. At low concentrations quinonamid acts as a photosynthetic electron transport blocker, whereas Hoe 17399 is a weak inhibitor of photosynthetic electron flow. Mode of action of the two naphthoquinones is discussed. Both naphthoquinone derivatives can operate as an electron acceptor for PS I at low concentra­tions (10-5-10-6м). In addition there is observed a strong stimulation of dark respiration in algal cells induced by both of the compounds, Hoe 17399 causes a much higher stimulation rate than quinonamid does.

Reinvestigation of the Effects of Disalicylidenepropanediamine (DSPD) and 2-Hepty-4-hydroxyquinoline-N-oxide (HQNO) on Photosynthetic Electron Transport

1981 ◽  
Vol 36 (1-2) ◽  
pp. 109-114 ◽  
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Reduced Form ◽  
Similar Extent ◽  
Ps Ii ◽  
Ps I ◽  
Inhibitory Site ◽  
High Concentrations ◽  
Dark Decay

Abstract The effects of disalicylidenepropanediamine (DSPD) and 2-heptyl-4-hydroxyquinoline-Noxide (HQNO) on photosynthetic electron transport have been reexamined. The results confirm earlier observations that lower concentrations of DSPD (< 100μᴍ) block electron transport at the levels of ferredoxin and plastocyanin. High concentrations of DSPD even inhibit electron transport from H2O → pBQ, suggesting that DSPD has an inhibitory site in PS II as well. Thermoluminescence curves of DSPD and DCMU treated chloroplasts were very similar, showing that the third inhibitory site of DSPD is similar to that of DCMU. Both oxidized and reduced HQNO, (0.6-6 μᴍ) blocked electron transport from H2O → pBQ, H2O → MV/FeCy to a similar extent. The effect of HQNO on thermoluminescence showed that its inhibitory site is probably located before that of DCMU. At higher concentration (> 6 μᴍ), the H2O → MV/FeCy reactions were more strongly inhibited by oxidized HQNO than those occuring from H2O → pBQ, suggesting that a new site of inhibition must also be considered. The dark decay of the P 700 signal was not influenced by the addition of oxidized HQNO which shows that the new inhibitory site of HQNO is located between plastoquinone and P 700. The reduced form of HQNO did not inhibit non-cyclic electron transport around PS I. Indeed, at higher concentrations, reduced HQNO even accelerates electron flow from DCIP → MV and the dark reduction of P 700, thus suggesting that this compound has a “donor-mediator” function in PS I.

Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 374-377 ◽  
Author(s):  
J. J. S. van Rensen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Amaranthus Hybridus ◽  
Apparent Affinity ◽  
Photosynthetic Electron Flow ◽  
Different Characteristics ◽  
The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

Rewiring photosynthesis: a photosystem I-hydrogenase chimera that makes H2in vivo

2020 ◽  
Vol 13 (9) ◽  
pp. 2903-2914 ◽  
Author(s):  
Andrey Kanygin ◽  
Yuval Milrad ◽  
Chandrasekhar Thummala ◽  
Kiera Reifschneider ◽  
Patricia Baker ◽  
...  
Keyword(s):  
Electron Transport ◽  
Hydrogen Production ◽  
Photosystem I ◽  
Electron Transport Chain ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain

Photosystem I-hydrogenase chimera intercepts electron flow directly from the photosynthetic electron transport chain and directs it to hydrogen production.

Inhibition by Tetranitromethane of Photosynthetic Electron Transport from Water to Photosystem II in Chloroplasts

1980 ◽  
Vol 35 (3-4) ◽  
pp. 293-297 ◽  
Author(s):  
P. V. Sane ◽  
Udo Johanningmeier
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Ph Dependence ◽  
Photosynthetic Electron Transport ◽  
Donor Side ◽  
Ps Ii ◽  
Diphenyl Carbazide ◽  
Low Concentrations ◽  
Sh Group

Abstract Low concentrations (10 µM) of tetranitromethane inhibit noncyclic electron transport in spinach chloroplasts. A study of different partial electron transport reactions shows that tetranitromethane primarily interferes with the electron flow from water to PS II. At higher concentrations the oxidation of plastohydroquinone is also inhibited. Because diphenyl carbazide but not Mn2+ ions can donate electrons efficiently to PS II in the presence of tetranitromethane it is suggested that it blocks the donor side of PS II prior to donation of electrons by diphenyl carbazide. The pH dependence of the inhibition by this protein modifying reagent may indicate that a functional-SH group is essential for a protein, which mediates electron transport between the water splitting complex and the reaction center of PS II.

scholarly journals Photosynthesis Regulation in Response to Fluctuating Light in the Secondary Endosymbiont Alga Nannochloropsis gaditana

2019 ◽  
Vol 61 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Alessandra Bellan ◽  
Francesca Bucci ◽  
Giorgio Perin ◽  
Alessandro Alboresi ◽  
Tomas Morosinotto
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Incident Light ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Thermal Dissipation ◽  
Photochemical Quenching ◽  
Nannochloropsis Gaditana ◽  
Fluctuating Light ◽  
Light Fluctuations

Abstract In nature, photosynthetic organisms are exposed to highly dynamic environmental conditions where the excitation energy and electron flow in the photosynthetic apparatus need to be continuously modulated. Fluctuations in incident light are particularly challenging because they drive oversaturation of photosynthesis with consequent oxidative stress and photoinhibition. Plants and algae have evolved several mechanisms to modulate their photosynthetic machinery to cope with light dynamics, such as thermal dissipation of excited chlorophyll states (non-photochemical quenching, NPQ) and regulation of electron transport. The regulatory mechanisms involved in the response to light dynamics have adapted during evolution, and exploring biodiversity is a valuable strategy for expanding our understanding of their biological roles. In this work, we investigated the response to fluctuating light in Nannochloropsis gaditana, a eukaryotic microalga of the phylum Heterokonta originating from a secondary endosymbiotic event. Nannochloropsis gaditana is negatively affected by light fluctuations, leading to large reductions in growth and photosynthetic electron transport. Exposure to light fluctuations specifically damages photosystem I, likely because of the ineffective regulation of electron transport in this species. The role of NPQ, also assessed using a mutant strain specifically depleted of this response, was instead found to be minor, especially in responding to the fastest light fluctuations.

Characteristics of Cu deficiency-induced inhibition of photosynthetic electron transport in spinach chloroplasts

1987 ◽  
Vol 891 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Magdolna Droppa ◽  
Jiři Masojidek ◽  
Zsuzsanna Rózsa ◽  
Adam Wolak ◽  
LászlóI. Horváth ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Spinach Chloroplasts ◽  
Cu Deficiency
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