Characterization of the Inhibition of Photosynthetic Electron Transport in Pea Chloroplasts by the Herbicide 4,6-Dinitro-o-cresol by Comparative Studies with 3-(3,4-Dichlorophenyl)-1,1- dimethylurea

Rensen, J.J.S. van; Wong, Daniel; Govindjee, null

doi:10.1515/znc-1978-5-617

Cited by 43 publications

(12 citation statements)

References 14 publications

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“…Their site of action was established in several ways. For DNOC it was investigated by measuring its effects on various parts of the electron transport chain [50,53,55]. In the presence of the inhibitor dibromothymoquinone the electron transport, after addition of the electron acceptors phenylenediamine and ferricyanide (FeCy), involves the electron carriers between water and the plastoquinone pool.…”

Section: Site Of Action Of Photosystem II Herbicidesmentioning

confidence: 99%

Regulation of photosynthetic electron transport by bicarbonate formate and herbicides in isolated broken and intact chloroplasts

Rensen

Snel

1985

Photosynth Res

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In this paper, we have presented a minireview on the interaction of bicarbonate, formate and herbicides with the thylakoid membranes.The regulation of photosynthetic electron transport by bicarbonate, formate and herbicides is described. Bicarbonate, formate, and many herbicides act between the primary quinone electron acceptor QA and the plastoquinone pool. Many herbicides like the ureas, triazines and the phenol-type herbicides act, probably, by the displacement of the secondary quinone electron acceptor QB from its binding site on a QB-binding protein located at the acceptor side of Photosystem II. Formate appears to be an inhibitor of electron transport; this inhibition can be removed by the addition of bicarbonate. There appears to be an interaction of the herbicides with bicarbonate and/or It has been suggested that both the binding of a herbicide and the absence of bicarbonate may cause a conformational alteration of the environment of the QB-binding site. The alteration brought about by a herbicide decreases the affinity for another herbicide or for bicarbonate; the change caused by the absence of bicarbonate decreases the affinity for herbicides. Moreover, this change in conformation causes an inhibition of electron transport. A bicarbonate-effect in isolated intact chloroplasts is demonstrated.

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Section: Site Of Action Of Photosystem II Herbicidesmentioning

confidence: 99%

Regulation of photosynthetic electron transport by bicarbonate formate and herbicides in isolated broken and intact chloroplasts

Rensen

Snel

1985

Photosynth Res

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“…Furthermore, since the Hill coef ficient (slope of the curve) can never be greater than the number of binding sites per molecule (Dahlquist, 1978) it is logical to deduce that two of the La-crown susceptible sites provide at least two binding domains for the inhibitor (with Hill coefficients 1.6 and 1.7). It may be mentioned that DCM U has been shown to possess two binding sites (Van Rensen et al, 1978). In this report we have presented experiments which certify the inhibitory action of La-crown at the reducing side of PS II and the characteristic inhibition refers both to phenolic and urea type of inhibition.…”

Section: Resultsmentioning

confidence: 54%

“…4 inset). The value of 0.17 ^im is rather high compared to DCMU that has a K; of about 10 to 40 nM (Van Rensen et al, 1978) in isolated chlo roplasts. Using the Ki; the concentration of specific bind ing sites for La-crown was determined following the equation I5 0 = K ; + 1/2 X t (Tischer and Strotmann, 1977).…”

Section: Resultsmentioning

confidence: 79%

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Inhibitory Effects of Synthetic Lanthanum-Crown Ether at the Reducing Side of Photosystem II

Sabat

Padhye

Mohanty

1998

Zeitschrift Für Naturforschung C

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Beta vulgaris, Electron Transport Inhibition, Lanthanum Crown, Photosystem II ParticlesInhibitory effects of lanthanum-crown [La-(Pic)3 (15-crown-6) 3H2OJ.was investigated on the 0 2 evolution activity of photsystem II particles. Lanthanum (La)-crown inhibited the electron flow at the reducing side of PS II complex. Short duration ( 1 -2 min) treatment of PS II membranes with trypsin partly developed resistance to La-crown inhibition. However, longer proteolytic treatment (>2 min) appeared to expose newer site(s) for La-crown inhibi tion. The inhibitory constant (K,) for La-crown was nearly 0.17 | j ,m . This inhibitory capacity is about 4 to 5 times less than the potent PS II inhibitor diuron which also binds at the acceptor side of PS II. The number of binding sites for La-crown was found to be 1 per 20 chlorophyll molecules. The Hill plot analysis showed the presence of three distinct straight lines suggesting that the compound acts at least at three sites. Furthermore, from the slope value (Hill coefficient) it is suggested that two of these sites provide minimum of two binding domains for the inhibitor.

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“…Thylakoid membranes were isolated from the leaves as described elsewhere (Van Rensen et al 1978). The isolation medium contained 0.3 M sorbitol, 50 mM Tricine-NaOH (pH 7.5), 100 mM KC1, 10 mM NaCI, 2 mM MgC12 and 2 mM MnC1 r Chloroplasts were broken in a medium containing 10 mM TricineNaOH (pH 7.6), 10 mM NaC1 and 5 mM MgC1 r Thylakoids were stored at -80 °C.…”

Section: Methodsmentioning

confidence: 99%

High misses after odd flashes in oxygen evolution in thoroughly dark-adapted thylakoids from pea and Chenopodium album

Naber

Rensen

1993

Photosynth Res

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In Photosystem II (PS II), water is oxidized to molecular oxygen and plastoquinone is reduced to plastoquinol. The oxidation of water requires the accumulation of four oxidizing equivalents, through the so-called S-states of the oxygen evolving complex; the production of plastoquinol requires the accumulation of two reducing equivalents on a bound plastoquinone, QB. It has been generally believed that during the flash-induced transition of each of the S-states (Sn → Sn+1, where n=0, 1, 2 and 3), a certain small but equal fraction of the PS II reaction centers are unable to function and, thus, 'miss' being turned over. We used thoroughly dark-adapted thylakoids from peas (Pisum sativum) and Chenopodium album (susceptible and resistant to atrazine) starting with 100% of the oxygen evolving complex in the S1 state. Thylakoids were illuminated with saturating flashes, providing a double hit parameter of about 0.07. Our experimental data on flashnumber dependent oscillations in the amount of oxygen per flash fit very well with a binary pattern of misses: 0, 0.2, 0, 0.4 during S0 → S1, S1 → S2, S2 → S3 and S3 → S0 transitions. Addition of 2 mM ferricyanide appears to shift this pattern by one flash. These results are consistent with the 'bicycle' model recently proposed by V. P. Shinkarev and C. A. Wraight (Oxygen evolution in photosynthesis: From unicycle to bicycle, 1993, Proc Natl Acad Sci USA 90: 1834-1838), where misses are due to the presence of P(+) or QA (-) among the various equilibrium states of PS II centers.

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Characterization of the Inhibition of Photosynthetic Electron Transport in Pea Chloroplasts by the Herbicide 4,6-Dinitro-o-cresol by Comparative Studies with 3-(3,4-Dichlorophenyl)-1,1- dimethylurea

Cited by 43 publications

References 14 publications

Regulation of photosynthetic electron transport by bicarbonate formate and herbicides in isolated broken and intact chloroplasts

Regulation of photosynthetic electron transport by bicarbonate formate and herbicides in isolated broken and intact chloroplasts

Inhibitory Effects of Synthetic Lanthanum-Crown Ether at the Reducing Side of Photosystem II

High misses after odd flashes in oxygen evolution in thoroughly dark-adapted thylakoids from pea and Chenopodium album

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