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1984 (1)
1Author    Z. NaturforschRequires cookie*
 Title    Redox-State Dependent Changes of Inhibitor-Binding to the Photosystem II Acceptor Complex  
 Abstract    Binding o f radioactively labelled D C M U , ioxynil and terbutryn to spinach chloroplasts is determined following preillum ination by single-turnover, saturating light flashes. W ith all o f the three herbicides binary oscillations o f binding are observed. D ark-adapted sam ples, or those pre­ illuminated by an even number o f flashes, bind more inhibitor than sam ples preillum inated by an odd number o f flashes. Binding oscillations depend on inhibitor incubation tim e and on the seasonal adaptation o f the plants. The binding kinetics follow ing a single flash display three phases, the last two o f which can be correlated with reoxidation kinetics o f the secondary p h oto­ system II acceptor Qb, as determined by fluorescence measurem ents. Analysis o f the binding at DCM U concentrations up to 10"7 M free D C M U yields identical binding constants for dark-and flash preilluminated samples, but much less binding sites follow ing one flash. It is concluded that up to 10~7 M free DCM U, centers with bound Q b do not contribute significantly to total binding. Displacement o f Q b from the binding site is half-saturated at about 10-6 M D C M U , as m onitored via fluorescence induction. The data are considered strong support for the Velthuys 'inhibitor-Q i competition model'. 
  Reference    Z. Naturforsch. 39c, 397 (1984); received D ecem ber 1 1983 
  Published    1984 
  Keywords    Inhibitor Binding, Photosystem II, Binary O scillation, Chlorophyll Fluorescence 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0397.pdf 
 Identifier    ZNC-1984-39c-0397 
 Volume    39