| | 1 | Author
| P. He, R. Schulder, K. P. Bader, G. H. Schmid | Requires 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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| default:Reihe_C/47/ZNC-1992-47c-0069.pdf | | | | Identifier
| ZNC-1992-47c-0069 | | | | Volume
| 47 | |
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