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1981 (1)
1Author    KatherineE. Steinback, Klaus Pfister, CharlesJ. AmtzenRequires cookie*
 Title    Trypsin-Mediated Removal of Herbicide Binding Sites within the Photosystem II Complex  
 Abstract    Trypsin treatment of isolated chloroplast thylakoids resulted in a step-wise modification o f surface exposed membrane polypeptides. Early effects o f the protease action resulted in a decrease in inhibitory activity of atrazine, diuron, pyrazon, and bromacil, but an initial increase in the activity of bromnitrothymol and dinoseb. Direct measurements o f atrazine binding demonstrated that decreased inhibitory activity corresponded to a decreased binding affinity in the treated membranes. Longer term effects o f trypsin caused removal of atrazine binding sites and a concomitant block o f electron transport chains. The data are consistent with a concept that the traizine receptor protein is a component o f the electron transport chain which is successively degraded in two or more steps by protease attack. Polyacrylamide gel electrophoresis of trypsin-treated membranes and sub-membrane fragments derived from these membranes revealed that several polypeptides are membrane surface exposed. The involvement o f a 32000 dalton polypeptide in creating the atrazine binding site is discussed. 
  Reference    Z. Naturforsch. 36c, 98 (1981); received September 221980 
  Published    1981 
  Keywords    Photosynthesis, Atrazine, Diuron, Chloroplast Membranes, Receptor Protein 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0098.pdf 
 Identifier    ZNC-1981-36c-0098 
 Volume    36 
2Author    D. Anny, J. Blubaugh, G. OvindjeeRequires cookie*
 Title    Comparison of Bicarbonate Effects on the Variable Chlorophyll a Fluorescence of C 0 2-Depleted and Non-C02-Depleted Thylakoids in the Presence of Diuron  
 Abstract    Evidence is presented from chlorophyll a fluorescence transient data for two sites o f bicar­ bonate (H C O j*) action in photosystem II. Both the absence o f H C O j (H C O j-depleted thyla­ koids) and a high concentration o f H C O j (60 m M H C O j added to non-depleted thylakoids) accelerate the variable chlorophyll a fluorescence rise in the presence o f 10 |i m diuron (D C M U). In non-HCOj-depleted thylakoids the effect is independent o f the order in which H C O j and DCM U are added, whereas in H CO J-depleted thylakoids, the effect is seen only when H C O j is added before DCM U. We propose that the effect seen in H C O j-depleted thylakoids is indirectly due to the binding o f H C O j functionally near the site o f D C M U binding, which is also where H CO j exerts its major effect on electron transport between the primary quinone QA and the plasto-quinone pool. We suggest that the smaller effect seen in non-HCOj-depleted thylakoids is due to the binding of HCOj at a second, lower affinity site. Binding at this site appears to require light, in con­ trast to the higher affinity site, which is inhibited by light. Bathocuproine, an inhibitor o f the H20 -to-silicomolybdate partial reaction, is synergistic with H C O j in its effect on the variable chlorophyll a fluorescence o f non-H C O j-depleted thylakoids, and may bind heterotropically with H CO j. Thus, this second site o f H C O j binding appears to be functionally near the batho­ cuproine binding site. 
  Reference    Z. Naturforsch. 39c, 378 (1984); received N ovem ber 14 1983 
  Published    1984 
  Keywords    Bicarbonate Effect, Chlorophyll Fluorescence, Photosystem II, Diuron, Bathocuproine 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0378.pdf 
 Identifier    ZNC-1984-39c-0378 
 Volume    39 
3Author    MarcelA K Jansen3, Shmuel Malkinb, Marvin EdelmanaRequires cookie*
 Title    Differential Sensitivity of 32 kDa-D 1 Protein Degradation and Photosynthetic Electron Flow to Photosystem II Herbicides  
 Abstract    Degradation of the 32 kDa-D 1 protein, a photosystem II reaction centre component, was studied as a function of linear electron flow in visible light in the presence of various photosys­ tem II herbicides. Under these conditions, herbicide specific effects on protein degradation were clearly evident. 32 kDa-D 1 protein degradation and electron flow between Q a and Q b proved to be only partially correlated. We conclude that inhibition of protein degradation by PS II herbicides in visible light is not simply correlated to displacement of Q b. 
  Reference    Z. Naturforsch. 45c, 408—411 (1990); received December 12 1989 
  Published    1990 
  Keywords    Diuron, Bromoxynil, Dinoseb, Oxygen, Evolution, Chlorophyll, Fluorescence 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0408.pdf 
 Identifier    ZNC-1990-45c-0408 
 Volume    45 
4Author    Jack Farineaua, DanielleM. Laval-, ArtinbRequires cookie*
 Title    Characteristics of Thermoluminescence Bands of Euglena Cells Belonging to 2 Lines Presenting Different Degrees of Diuron-Resistance  
 Abstract    We have analysed the thermoluminescence (TL) properties of two lines o f Euglena exhibit­ ing two degrees of resistance to diuron, by a factor of 100 (Z R 25) and 1000 (Z R 250) respectively, as compared to wild type line (Z). In addition, the two ZR lines developped an identical resistance to atrazine since the I50 for this herbicide in each line was 75 times larger than in wild type. Special TL characteristics were evidenced in the two lines. Bands after 2 flashes (or more) showed a shift o f the peak maximum towards low temperature, the shift being the largest in the most DCM U-resistant cells. Similar results were obtained with isolated thylakoids, except that the TL bands appeared at a temperature higher than in corresponding cells. Oscillations in the amplitude of the bands in a flash sequence were largely damped in cells (and thylakoids), particularly in the most DCM U-resistant lines. The results are interpreted as indicating accumulation of Q a "Qb after flashes due to a decrease of the equilibrium constant for the reaction Q a ~Qb ^ QaQb~ accompanying the D CM U resistance. 
  Reference    Z. Naturforsch. 50c, 86—9 (1995); received October 12/November 21 1994 
  Published    1995 
  Keywords    Diuron, Euglena, Herbicide-Resistance, Photosystem II, Thermoluminescence 
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 TEI-XML for    default:Reihe_C/50/ZNC-1995-50c-0086.pdf 
 Identifier    ZNC-1995-50c-0086 
 Volume    50 
5Author    HelenG M Cfadden, JohnN. PhillipsRequires cookie*
 Title    Synthesis and Use of Radiolabelled Cyanoacrylate Probes of the Photosystem II Herbicide Binding Site  
 Abstract    Cyanoacrylates are potent inhibitors o f photosynthetic electron transport (PET) and are po­ tentially useful probes o f the photosystem II herbicide binding site. A series o f cyanoacrylates was synthesized and the Hill inhibition activities evaluated in order to select com pounds suita­ ble for radioactive synthesis. A cyanoacrylate, 2-(2-nitrophenoxy)ethyl 3-benzylamino-2-cyano-2-pentenoate, was found to displace diuron from the photosystem II herbicide binding site. For this compound the dissociation constant o f the inhibitor/binding site complex was found to be 2 x 10"8 M with an active site concentration o f 2 nm ol/m g chlorophyll. In a similar system the corresponding figures for diuron were 1.2 x 10"8 m and 1.3 nm ol/m g chlorophyll. Photoaffinity labelling o f 1% II thylakoid proteins with 2-(2-azidophenoxy)ethyl 3-[7-l4C]-benzylam ino-2-cyano-2-pentenoate showed weak binding in the 32 and 28 kD mass regions, consistent with binding to the D, peptide. 
  Reference    Z. Naturforsch. 45c, 196—202 (1990); received September 20/N ovem ber 10 1989 
  Published    1990 
  Keywords    Cyanoacrylate, Photoaffinity Labelling, Photosystem II, Com petitive Inhibition, Diuron 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0196.pdf 
 Identifier    ZNC-1990-45c-0196 
 Volume    45