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1Author    P. He, R. Schulder, K. P. Bader, G. H. SchmidRequires cookie*
 Title    Effect of Cyanide on the S2-and S3-State in the Filamentous Cyanobacterium Oscillatoria chalybea  
 Abstract    Filam Low concentrations o f cyanide affect the flash-induced oxygen evolution pattern in thyla-koid preparations o f the filamentous cyanobacterium Oscillatoria chalybea. At a cyanide con­ centration o f 2 x 10~6 m the effect lies exclusively on the S2-and S3-state whereas the sub­ sequent flash yields and the steady state are barely affected, showing that the reaction center is not touched by the reagent. The influence o f the chemical is characterized by the fact that at basic pH (7 .5 -8 .5) the deactivation mode o f S2 and S3 is changed, showing that the cyanide-ion is the reactant. Whereas in the control the deactivation o f S, yields as usual S, and S_,, the deactivation pattern in the presence o f cyanide shows that S2 deactivates -without giving S, -, to a more reduced state, probably S0. In the flash pattern the two signal amplitudes o f the first two flashes are lowered to zero in the presence o f 2 x 10~6 m cyanide and becom e uptake signals at higher cyanide concentrations. It is seen that in the presence o f cyanide S2 and to a lesser extent S3 in the Oscillatoria system apparently react with oxygen. In tobacco thylakoids no effect o f cyanide on the flash pattern itself is observed, even at higher concentrations (e.g. 1 0 " 4 m), although the signal amplitudes o f the entire pattern are affected at such concentra­ tions. Photosystem II o f cyanobacteria is characterized by the absence o f the two extrinsic 16 kD a and 23 kD a peptides. As shown by mass spectrometry inside-out vesicles from tobacco thylakoids, in which these two extrinsic peptides have been removed by NaCl-washing, exhibit sim ultaneously flash-induced 0 2-evolution and an 0 2-uptake which both require the presence o f CL and C a2+ ions. Both the evolution signal and the uptake signal are D C M U sensitive and are inhibited by KCN. An amperometrically measured flash pattern o f inside-out tobacco ves­ icles shows, if the assay is supplemented with CL ions, the usual flash pattern known from the literature. The experiments seem to indicate that even in the washed inside-out condition the S-state system o f higher plants is much less sensitive to ambient oxygen than in the phylo-genetically older system o f the filamentous cyanobacterium Oscillatoria chalybea. 
  Reference    Z. Naturforsch. 47c, 69—7 (1992); received September 30 1991 
  Published    1992 
  Keywords    entous Cyanobacterium, Water-Splitting, S-States 
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 TEI-XML for    default:Reihe_C/47/ZNC-1992-47c-0069.pdf 
 Identifier    ZNC-1992-47c-0069 
 Volume    47