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1992 (1)
1984 (1)
1Author    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 
2Author    ChunheX. Ua, Yong Zhub, GovindjeeacRequires cookie*
 Title    Differential Inhibition and Rephasing of Photosystem II Electron Acceptor Side by Monohalogenated Acetates of Different Hydrophobicity  
 Abstract    We demonstrate here that monohalogenated acetates (M F A , m onofluoroacetate; M CA, m onochloroacetate; M BA, monobrom oacetate) are unique probes o f the electron acceptor side o f the photosystem II (PS II) reaction center: (1) they differentially inhibit the reoxidation o f the reduced primary plastoquinone electron acceptor, QA~, by the secondary plastoquinone electron acceptor QB, and increase the equilibrium [QA_] in the order: M BA > M C A > M FA; and (2) M CA and M BA rephase the PS II electron acceptor side, a rather unusual effect. This results in flash number dependence o f [QA_] with maxima at even flashes to change to odd flashes. Furthermore, we demonstrate a correlation between the inhibitory activity o f the halo-genated acetates with their hydrophobicity (i.e., partition coefficient). 
  Reference    Z. Naturforsch. 47c, 711—7 (1992); received June 2 1992 
  Published    1992 
  Keywords    M onohalogenated Acetates, Photosystem II, Two Electron Gate, Hydrophobicity, Bicarbonate Effect 
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 TEI-XML for    default:Reihe_C/47/ZNC-1992-47c-0711.pdf 
 Identifier    ZNC-1992-47c-0711 
 Volume    47