Effect of Irradiation and Immobilization on Spinach Chloroplast Activities

1980 ◽  
Vol 35 (5-6) ◽  
pp. 477-481 ◽  
Author(s):  
T. Fujimura ◽  
F. Yoshii ◽  
I. Kaetsu ◽  
Y. Inoue ◽  
K. Shibata
Keyword(s):  
Low Temperature ◽  
Active Center ◽  
Polymer Matrix ◽  
O2 Evolution ◽  
Hydrophilic Polymer ◽  
Spinach Chloroplast ◽  
Ps Ii ◽  
Thermo Stability ◽  
Ps Ii Activity ◽  
Isolated Chloroplasts

Abstract The effect of y-ray irradiation and immobilization by means of radiation polymerization on PS II activity (O2 evolution) of isolated chloroplasts from spinach was investigated. Reduction of O2 evolution activity by irradiation was small at lower temperatures below – 24 °C, but the activity decreased slightly by freezing at extremely low temperature below –78 °C. So the optimum low temperature range for the treatment was observed. The immobilized chloroplast in a hydrophilic polymer matrix showed the stable duration of O2 evolution activity more than 700 h at 4 °C . Thermo-stability of chloroplast was also improved greatly by immobilization. The active center of PS II in immobilized chloroplasts was retained even after 60 min standing at 50 °C.

Comparative Triazine Effects Upon System II Photochemistry in Chloroplasts of Two Common Lambsquarters(Chenopodium album)Biotypes

Weed Science ◽  
1978 ◽  
Vol 26 (4) ◽  
pp. 318-322 ◽  
Author(s):  
V. Souza Machado ◽  
C. J. Arntzen ◽  
J. D. Bandeen ◽  
G. R. Stephenson
Keyword(s):  
Electron Transport ◽  
Chenopodium Album ◽  
Chloroplast Envelope ◽  
Hill Reaction ◽  
Ps Ii ◽  
Common Lambsquarters ◽  
Relative Tolerance ◽  
The Hill ◽  
Ps Ii Activity ◽  
Isolated Chloroplasts

Biotypes of several annual broadleaved weeds tolerant to 2-chloro-s-triazines have been recorded, including common lambsquarters(Chenopodium albumL.). The mechanism of resistance in common lambsquarter was based on the differential inhibition of the Hill reaction in chloroplasts by atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine]. Chlorophyll fluorescence and electron transport assays were used with isolated chloroplasts of atrazine-tolerant and susceptible biotypes, to determine the effect of atrazine and diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] on photosystem II (PS II) activity, differential atrazine penetration of the chloroplast envelope, and relative tolerance to chloro, methoxy, and methylthio triazines. Atrazine and diuron inhibited electron transport on the reducing side of PS II in susceptible biotype chloroplasts. In tolerant biotype chloroplasts only diuron inhibited electron transport whereas atrazine had only slight effects. There were no differences in the chloroplast membrane permeability to atrazine in the two biotypes. Chloroplasts of the atrazine-tolerant biotype of common lambsquarters were also tolerant to the other classes of triazines tested.

Isolierung von PS II-Partikeln mit in vivo Eigenschaften aus Euglena gracilis, Stamm Z / Isolation of PS II-Particels with in vivo Characteristics from Euglena gracilis, Stamm Z

1982 ◽  
Vol 37 (3-4) ◽  
pp. 256-259 ◽  
Author(s):  
F. Schuler ◽  
P. Brandt ◽  
W. Wießner
Keyword(s):  
Euglena Gracilis ◽  
Fluorescence Emission ◽  
Improved Method ◽  
Ps Ii ◽  
Ps I ◽  
Emission And Absorption Spectra ◽  
Chlorophyll Protein ◽  
Ps Ii Activity ◽  
Photosystem Ii Particles

Abstract An improved method for isolation of (photosystem II)-particles from Euglena gracilis, strain Z was established. PS II-particles isolated by ultrasonic treatment and following differential centrifugation show fluorescence emission and absorption spectra identical with in vivo properties of Euglena gracilis. These PS II-particles have only PS II-activity and contain CP a, the typical chlorophyll-protein-complex of PS II. No contamination of PS I-components are detectable.

Site-Directed Mutations of Two Histidine Residues in the D2 Protein Inactivate and Destabilize Photosystem II in the Cyanobacterium Synechocystis 6803

1987 ◽  
Vol 42 (7-8) ◽  
pp. 762-768 ◽  
Author(s):  
Wim F. J. Vermaas ◽  
John G. K. Williams ◽  
Charles J. Arntzen
Keyword(s):  
Low Temperature ◽  
Photosystem Ii ◽  
Purple Bacteria ◽  
Synechocystis 6803 ◽  
Ps Ii ◽  
Histidine Residues ◽  
Fluorescence Maximum ◽  
Herbicide Binding ◽  
Chlorophyll Protein ◽  
D2 Protein

Site-directed mutations were created in the cyanobacterium Synechocystis 6803 to alter specific histidine residues of the photosystem II (PS II) D2 protein. In one mutant (tyr-197). the his-197 residue was replaced by tyrosine, in another mutant (asn-214), his-214 was changed into asparagine. The tyr-197 mutant did not show any low-temperature fluorescence attributable to PS II. but contained a PS II chlorophyll-protein, CP-47, in significant quantities. Another PS II chlorophyll-protein, CP-43, was absent, as was PS II-related herbicide binding. The asn-214 mutant showed a blue-shifted low-temperature fluorescence maximum around 682 nm. but did not have a significant amount of membrane-incorporated CP-43 or CP-47. Herbicide binding was also absent in this mutant. These data indicate a very important role of the his-197 and his-214 residues in the D 2 protein, and are interpreted to support the hypothesis that the D2 protein and the M subunit from the photosynthetic reaction center of purple bacteria have analogous functions. According to this hypothesis, his-197 is involved in binding of P680. and his-214 forms ligands with Qᴀ and Fe2+. In absence of a functional D2 protein, the PS II core complex appears to be destabilized as evidenced by loss of chlorophyll-proteins in the mutants.

Sign in / Sign up

Export Citation Format

Share Document