Structural analysis of photosystem II in far-red-light-adapted thylakoid membranes

2000 ◽  
Vol 267 (1) ◽  
pp. 207-215 ◽  
Author(s):  
Svetla Stoylova ◽  
Toby D. Flint ◽  
Robert C. Ford ◽  
Andreas Holzenburg
Keyword(s):  
Structural Analysis ◽  
Photosystem Ii ◽  
Red Light ◽  
Thylakoid Membranes

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.

scholarly journals Singlet oxygen damages the function of Photosystem II in isolated thylakoids and in the green alga Chlorella sorokiniana

2021 ◽  
Author(s):  
Faiza Bashir ◽  
Ateeq Ur Rehman ◽  
Milán Szabó ◽  
Imre Vass
Keyword(s):  
Photosystem Ii ◽  
Singlet Oxygen ◽  
Screening Method ◽  
Physiological Role ◽  
Thylakoid Membranes ◽  
Chlorella Sorokiniana ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Intact Cells ◽  
Green Alga Chlorella

AbstractSinglet oxygen (1O2) is an important damaging agent, which is produced during illumination by the interaction of the triplet excited state pigment molecules with molecular oxygen. In cells of photosynthetic organisms 1O2 is formed primarily in chlorophyll containing complexes, and damages pigments, lipids, proteins and other cellular constituents in their environment. A useful approach to study the physiological role of 1O2 is the utilization of external photosensitizers. In the present study, we employed a multiwell plate-based screening method in combination with chlorophyll fluorescence imaging to characterize the effect of externally produced 1O2 on the photosynthetic activity of isolated thylakoid membranes and intact Chlorella sorokiniana cells. The results show that the external 1O2 produced by the photosensitization reactions of Rose Bengal damages Photosystem II both in isolated thylakoid membranes and in intact cells in a concentration dependent manner indicating that 1O2 plays a significant role in photodamage of Photosystem II.

A Rapid Microtitre Plate Assay for Determining Sensitivity to Photosystem II Herbicides

Weed Science ◽  
1994 ◽  
Vol 42 (4) ◽  
pp. 517-522 ◽  
Author(s):  
Michael P. Anderson ◽  
Curtis N. Bensch ◽  
Jimmy F. Stritzke
Keyword(s):  
Photosystem Ii ◽  
Thylakoid Membranes ◽  
Microtitre Plate ◽  
Plate Assay ◽  
Conventional Procedure ◽  
Microtitre Plate Assay ◽  
Reduction Assay ◽  
Before And After ◽  
Chlorophyll Concentrations

This paper reports on a microtitre plate version of the 2,6-dichlorophenol-indophenol (DCPIP) reduction assay. DCPIP reduction rates of alfalfa thylakoid membranes were determined by measuring absorbance at 600 nm before and after a 1 min illumination period. The membranes were near light-saturated at intensities above 600 μE m–2s–1. Saturation of thylakoid membranes with DCPIP occurred above 120 μM. DCPIP reduction rates increased linearly with chlorophyll concentrations from 0.25 to 2 μg. The rate of DCPIP reduction was linear throughout a 2 min illumination period (R2= 0.99). The assay was sensitive enough to terbacil to differentiate between a 20% change in the I50concentration. DCPIP reduction rates were sensitive to concentrations of terbacil as low as 100 nM. It only takes 13 minutes to load and read 96 samples using the microtitre plate assay compared to 5.5 h using the conventional procedure.

Electron microscope and physical chemical characterization of C-phycocyanin from fresh extracts of two blue-green algae

1973 ◽  
Vol 19 (7) ◽  
pp. 831-836 ◽  
Author(s):  
Martin Kessel ◽  
Robert MacColl ◽  
Donald S. Berns ◽  
Mercedes R. Edwards
Keyword(s):  
Red Light ◽  
Chemical Characterization ◽  
Thylakoid Membranes ◽  
Sedimentation Velocity ◽  
Particulate Material ◽  
Thin Sections ◽  
Blue Green Algae ◽  
Physical Chemical ◽  
Sedimentation Velocity Centrifugation

The particulate material (intact and dissociated phycobilisomes), adjacent to the thylakoids of Plectonema boryanum and Calothrix parietina, was examined in thin sections and in freshly prepared C-phycocyanin extracts. For the latter a method was developed using spheroplasts of log-phase cells. When examined by sedimentation velocity centrifugation, the sedimentation coefficients of the rapidly extracted C-phycocyanin were found to be 18 S and 5 S. Also, a 10-S boundary was observed with P. boryanum. When C. parietina was grown under red light the 18-S aggregates increased to 20 S. The 18 S particles, in electron micrographs of negatively stained preparations, displayed eight subunits surrounding a central one. The possibility that some subunits fall out of the plane of view is contemplated in proposing a dodecamer arrangement for such particles. The 20-S particles were also examined by electron microscopy. However, the precise number of monomer units associated with either the 18-S or 20-S particles has not yet been ascertained. Thin sections of intact algal cells are presented to demonstrate the presence of phycobilisomes along the outer faces of the thylakoid membranes.

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