Effect of TCA-depletion of extrinsic polypeptides on electron transport on oxidizing side of PS II

1997 ◽  
Vol 42 (3) ◽  
pp. 227-231
Author(s):  
Rong Li ◽  
Yungang Shen ◽  
Chunhe Xu ◽  
Wei Lu ◽  
Tiecheng Tu ◽  
...  
Keyword(s):  
Electron Transport ◽  
Ps Ii ◽  
Extrinsic Polypeptides

Photosystem II Inhibition by Pyran-enamine Derivatives

1993 ◽  
Vol 48 (3-4) ◽  
pp. 163-167
Author(s):  
Koichi Yoneyama ◽  
Yoshihiro Nakajima ◽  
Masaru Ogasawara ◽  
Hitoshi Kuramochi ◽  
Makoto Konnai ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Thylakoid Membranes ◽  
Major Determinant ◽  
Ps Ii ◽  
Structure Activity Relationships ◽  
Structure Activity

Abstract Through the studies on structure-activity relationships of 5-acyl-3-(1-aminoalkylidene)-4-hydroxy-2 H-pyran-2,6(3 H)-dione derivatives in photosystem II (PS II) inhibition, overall lipophilicity of the molecule was found to be a major determinant for the activity. In the substituted N -benzyl derivatives, not only the lipophilicity but also the electronic and steric characters of the substituents greatly affected the activity. Their mode of PS II inhibition seemed to be similar to that of DCMU , whereas pyran-enamine derivatives needed to be highly lipophilic to block the electron transport in thylakoid membranes, which in turn diminished the permeability through biomembranes.

Photoinactivation of Photosynthetic Electron Transport under Anaerobic and Aerobic Conditions in Isolated Thylakoids of Spinach

1992 ◽  
Vol 47 (1-2) ◽  
pp. 63-68 ◽  
Author(s):  
Rekha Chaturvedi ◽  
M. Singh ◽  
P. V. Sane
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Oxygen Evolving Complex ◽  
Reaction Centre ◽  
Ps Ii ◽  
Ps I ◽  
S2 State ◽  
The Stability ◽  
Oxygen Evolving ◽  
Spinach Thylakoids

Abstract The effect of exposure to strong white light on photosynthetic electron transport reactions of PS I and PS II were investigated in spinach thylakoids in the absence or presence of oxygen. Irrespective of the conditions used for photoinactivation, the damage to PS II was always much more than to PS I. Photoinactivation was severe under anaerobic conditions compared to that in air for the same duration. This shows that the presence of oxygen is required for prevention of photoinactivation of thylakoids. The susceptibility of water-splitting complex in photoinactivation is indicated by our data from experiments with chloride-deficient chloroplast membranes wherein it was observed that the whole chain electron transport from DPC to MV was much less photoinhibited than that from water. The data from the photoinactivation experiments with the Tris-treated thylakoids indicate another photodam age site at or near reaction centre of PS II. DCMU-protected PS II and oxygen-evolving complex from photoinactivation. DCMU protection can also be interpreted in terms of the stability of the PS II complex when it is in S2 state.

X-Ray Structure Analysis of a Cyanoacrylate Inhibitor of Photosystem II Electron Transport

1991 ◽  
Vol 46 (1-2) ◽  
pp. 93-98 ◽  
Author(s):  
Helen G. McFadden ◽  
Donald C. Craig ◽  
John L. Huppatz ◽  
John N. Phillips
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll Concentration ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Ps Ii ◽  
X Ray ◽  
High Affinity ◽  
Modelling Studies ◽  
Intramolecular Hydrogen

Abstract X-ray crystallographic data for the highly potent cyanoacrylate photosynthetic electron transport inhibitor, (Z)-ethoxyethyl 3-(4-chlorobenzylamino)-2-cyano-4-methylpent-2-enoate, are presented. This compound has a particularly high affinity for the photosystem II (PS II) herbicide receptor with a p I50 value of 9.5 (in the Hill reaction under uncoupled condi­tions with a chlorophyll concentration of 0.1 μg/ml). Data regarding the structure of small li­gands, such as this potent cyanoacrylate, which bind to the site with high affinity may be used to provide the basis for modelling studies of PS II/herbicide complexes. The X-ray data presented confirm the Z-stereochemistry of active cyanoacrylates and demonstrate the pres­ence of a planar core stabilized by an intramolecular hydrogen bond between the ester car­bonyl oxygen and a benzylamino hydrogen atom. In order to assess the importance of the benzylamino -NH -group in this type of cyanoacrylate, analogues containing a methylene group in its place were synthesized and found to be 100-and 1000-fold less active as Hill inhibitors.

Glyphosate Does Not Inhibit Photosynthetic Electron Transport and Phosphorylation in Pea (Pisum sativum) Chloroplasts

Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 684-688 ◽  
Author(s):  
E. P. Richard ◽  
J. R. Goss ◽  
C. J. Arntzen
Keyword(s):  
Electron Transport ◽  
Pisum Sativum ◽  
Photosynthetic Electron Transport ◽  
Photochemical Reactions ◽  
Transport Processes ◽  
Ps Ii ◽  
Dark Incubation ◽  
Fluorescence Studies ◽  
Mixture Prior

The activity of glyphosate [N-(phosphonomethyl)glycine], formulated as the isopropylamine salt, on in vitro photosynthesis was investigated. When pH 4.7 glyphosate solutions were titrated to a pH equal to that of the reaction media (pH 7.8), glyphosate additions had no effect on whole chain electron transport between coupled photosystem II (PS II) and photosystem I (PS I) in stroma-free chloroplast thylakoids from peas (Pisum sativumL. ‘Morse's Progress No. 9′). Inhibition did not occur even after a 2-h dark incubation of lamellae in a 5-mM solution of glyphosate. Fluorescence studies failed to detect an effect of glyphosate on PS-II mediated electron transport processes or upon light harvesting properties of PS II even after a 2-h glyphosate/chloroplast preincubation. Glyphosate had no effect on cyclic and noncyclic photophosphorylation even after a 100-min dark incubation of chloroplast membranes in a 5-mM solution of glyphosate. Based on these assays it is concluded that glyphosate has no direct effect on the photochemical reactions of photosynthesis when the pH of the active compound is adjusted to that of the reaction mixture prior to addition to a chloroplast suspension.

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.

Quantum Yields of Photosystem II Electron Transport and Carbon Dioxide Fixation in C4 Plants

1990 ◽  
Vol 17 (5) ◽  
pp. 579 ◽  
Author(s):  
JP Krall ◽  
GE Edwards
Keyword(s):  
Carbon Dioxide ◽  
Electron Transport ◽  
Quantum Yield ◽  
Photosystem Ii ◽  
Malic Enzyme ◽  
Co2 Fixation ◽  
C4 Plants ◽  
Quantum Yields ◽  
Ps Ii ◽  
Co2 Concentrations

The quantum yields of non-cyclic electron transport from photosystem II (determined from chlorophyll a fluorescence) and carbon dioxide assimilation were measured in vivo in representative species of the three subgroups of C4 plants (NADP-malic enzyme, NAD-malic enzyme and PEP-carboxykinase) over a series of intercellular CO2 concentrations (CI) at both 21% and 2% O2. The CO2 assimilation rate was independent of O2 concentration over the entire range of Ci (up to 500 μbar) in all three C4 subgroups. The quantum yield of PS II electron transport was similar, or only slightly greater, in 21% v. 2% O2 at all Ci values. In contrast, in the C3 species wheat there was a large O2 dependent increase in PS II quantum yield at low CO2, which reflects a high level of photorespiration. In the C4 plants, the relationship of the quantum yield of PS II electron transport to the quantum yield of CO2 fixation is linear suggesting that photochemical use of energy absorbed by PS II is tightly linked to CO2 fixation in C4 plants. This relationship is nearly identical in all three subgroups and may allow estimates of photosynthetic rates of C4 plants based on measurements of PS II photochemical efficiency. The results suggest that in C4 plants both the photoreduction of O2 and photorespiration are low, even at very limiting CO2 concentrations.

Kinetic response of photosystem II photochemistry in the cyanobacterium Spirulina platensis to high salinity is characterized by two distinct phases

1999 ◽  
Vol 26 (3) ◽  
pp. 283 ◽  
Author(s):  
Congming Lu ◽  
Giuseppe Torzillo ◽  
Avigad Vonshak
Keyword(s):  
Electron Transport ◽  
Quantum Yield ◽  
Photosystem Ii ◽  
Spirulina Platensis ◽  
High Salinity ◽  
Photochemical Quenching ◽  
Second Phase ◽  
Ps Ii ◽  
Reaction Centres ◽  
Two Phases

The kinetic response of photosystem II (PS II) photochemistry in Spirulina platensis(Norstedt M2 ) to high salinity (0.75 M NaCl) was found to consist of two phases. The first phase, which was independent of light, was characterized by a rapid decrease (15–50%) in the maximal efficiency of PS II photochemistry (Fv /Fm), the efficiency of excitation energy capture by open PS II reaction centres (Fv′/Fm′), photochemical quenching (qp) and the quantum yield of PS II electron transport (Φ PS II) in the first 15 min, followed by a recovery up to about 80–92% of their initial levels within the next 2 h. The second phase took place after 4 h, in which further decline in above parameters occurred. Such a decline occurred only when the cells were incubated in the light, reaching levels as low as 45–70% of their initial levels after 12 h. At the same time, non-photochemical quenching (qN) and Q B -non-reducing PS II reaction centres increased significantly in the first 15 min and then recovered to the initial level during the first phase but increased again in the light in the second phase. The changes in the probability of electron transfer beyond QA (ψo) and the yield of electron transport beyond QA (φ Eo), the absorption flux (ABS/RC) and the trapping flux (TRo /RC) per PS II reaction centre also displayed two different phases. The causes responsible for the decreased quantum yield of PS II electron transport during the two phases are discussed.

Involvement of the Xanthophyll Cycle in Regulation of Cyclic Electron Flow around Photosystem II

1996 ◽  
Vol 51 (1-2) ◽  
pp. 47-52 ◽  
Author(s):  
W. I. Gruszecki ◽  
K. Strzałk ◽  
K.P. Bader ◽  
A. Radunz ◽  
G.H. Schmid
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Oxygen Evolution ◽  
Xanthophyll Cycle ◽  
Electron Flow ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Oxygen Evolution ◽  
Cyclic Electron Transport ◽  
Ps Ii ◽  
Low Levels

Abstract In our previous study (Gruszecki et al., 1995) we have postulated that the mechanism of cyclic electron transport around photosystem II, active under overexcitation of the photosynthetic apparatus by light is under control of the xanthophyll cycle. The combination of dif­ferent light quality and thylakoids having various levels of xanthophyll cycle pigments were applied to support this hypothesis. In the present work photosynthetic oxygen evolution from isolated tobacco chloroplasts was measured by means of mass spectrometry under conditions of high or low levels of violaxanthin, being transformed to zeaxanthin during dark incubation in an ascorbate containing buffer at pH 5.7. Analysis of oxygen evolution and of light-induced oxygen uptake indicate that the de-epoxidation of violaxanthin to zeaxanthin results in an increased cyclic electron transport around PS II, thus dimishing the vectorial electron flow from water. An effect similar to de-epoxidation was observed after incubation of thylakoid membranes with specific antibodies against violaxanthin.

Reed stands in constructed wetlands: “edge effect” and photochemical efficiency of PS II in common reed

1997 ◽  
Vol 35 (5) ◽  
pp. 143-147 ◽  
Author(s):  
Olga Urbanc-Bercic ◽  
Alenka Gaberšcik
Keyword(s):  
Electron Transport ◽  
Solar Radiation ◽  
Phragmites Australis ◽  
Constructed Wetlands ◽  
Photochemical Efficiency ◽  
Common Reed ◽  
Ps Ii ◽  
Ets Activity ◽  
The Common ◽  
Reed Bed

In this study an attempt has been made to estimate the vitality of the common reed (Phragmites australis) grown in the constructed wetland. The efficiency of solar radiation uptake of leaves was measured and terminal electron transport system (ETS) activity of roots was determined in specimens from different locations on the reed bed. The results showed that photochemical efficiency of PS II, expressed as FvFm ratio, was higher in plants growing in the middle of the well established stand, but it was lower in plants growing in the area permanently flooded with leachate, where plants were significantly lower. Potential respiration of roots on the vertical rhizome decreases with depth, while it showed slight variations when determined at the same depth, but in plants from different locations within three beds of RBTS.

Changes in Photosynthetic Apparatus in the Juvenile Rice Canopy and a Possible Function of Photosystem I in the Bottom Leaves

1999 ◽  
Vol 54 (11) ◽  
pp. 915-922 ◽  
Author(s):  
Jun-ya Yamazaki ◽  
Yasumaro Kamimura ◽  
Yasutomo Sugimura
Keyword(s):  
Electron Transport ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Performance ◽  
Cytochrome F ◽  
Transport Capacity ◽  
Ps Ii ◽  
Electrochromic Shift ◽  
The Third ◽  
Ps I ◽  
Light Utilization

Abstract Changes in the photosynthetic apparatus and relative antenna sizes of photosystem (PS) I and PS II were measured in the rice canopy. We used juvenile rice seedlings to examine light utilization and its absorption in the bottom leaves and obtained the following results: (1) When referred to chlorophyll (Chl), levels of the electrochromic shift at 550 nm and cytochrome ƒ decreased from the sixth to the third leaves, but there was no loss of pigment (P)-700. As a consequence, the PS II/PS I ratio significantly decreased from 1.5 in the sixth leaves to 0.9 in the third leaves. (2) The electron transport capacity in the sixth leaves was 1.5-times larger than that in the third leaves. (3) The levels of cytochrome b6 referred to Chl were almost constant from top to bottom. (4) The photosynthetic performance of the leaf de­creased concomitant with the depth, whereas the respiration was slightly increased. From these results, we hypothesize that there are maintenance mechanisms when the imbalances of light absorption and electron transport capacity occur in the bottom leaves.

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