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'Oxygen' in keywords Facet   Publication Year 1983  [X]
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1Author    GeorgH. Schmid, Pierre ThibaultRequires cookie*
 Title    Studies on the S-State Distribution in Euglena gracilis  
 Abstract    When Euglena gracilis is dark adapted for 10 min or more, oxygen evolution as the conse­ quence of short (5 usee) saturating light flashes does not show the picture of a damped oscillation with a periodicity o f 4, as known from the literature. The overall picture of this flash pattern is given by the fact that 0 2-evolution in the First two flashes is practically zero and rises from there onward in a continuous manner to the steady state with barely any visible oscillation at all. However, a second flash sequence fired one to two minutes after this first sequence induces an oxygen evolution pattern which is barely distinguishable from the well known usual Chlorella vulgaris pattern. The phenomenon is not influenced by changes in the oxygen tension nor do additions of chemicals like CCCP, sodium azide, or reducing agents like hydroxylamine or hydrogen peroxide substantially alter the described behavior. Deactivation experiments give the overall impression that the deactivation of the S-states is slower than with Chlorella. Hydroxylamine strongly accelerates the deactivation. The analysis of the S-state distribution in a four and five state Kok-model suggests that dark adapted Euglena is in a more reduced condition than dark adapted Chlorella. It looks as if dark adapted Euglena were in a condition which would correspond to 60 percent S_|, 30 percent S0 and 10 percent S). The experimental flash sequence of such dark adapted cells fits best a synthetic sequence when the misses are in the region of 2 0 -2 5 percent, with double hitting playing practically no role at all (the first two flashes are zero!). The impression that dark adapted Euglena starts its oxygen evolution from a more reduced state is strengthened by the analysis of room temperature fluorescence induction (Kautsky effect). It can be shown that the fluorescence induction curve o f Euglena corresponds to that of Chlorella cells provided the latter have been briefly treated with a strong reductant such as sodium dithionite. 
  Reference    Z. Naturforsch. 38c, 60—6 (1983); received September 1982 
  Published    1983 
  Keywords    Flash Yield, Oxygen, Euglena, Fluorescence Induction 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0060.pdf 
 Identifier    ZNC-1983-38c-0060 
 Volume    38 
2Author    Ahlert Schmidt, Elisabeth KrämerRequires cookie*
 Title    A Membrane Bound Cysteine Oxydase from the Cyanobacterium Synechococcus 6301  
 Abstract    Membrane fractions o f the cyanobacterium Synechococcus 6301 obtained by french press treatment following sonication catalyzed an oxygen-dependent oxydation o f cysteine to cystine. For 1 0 2 consumed four cysteine were oxydized. O xygen uptake was com pletely inhibited by 1 mM KCN. Only D-and L-cysteine were active and partial activity was observed with DL-homocysteine and cysteamine. N o activity was found with glutathione, mercaptoethanol, thioglycerol, dithioerythritol, or N-acetyl-L-cysteine. Cysteines with a blocked acid group such as O-methyl-L-cysteine and O-ethyl-L-cysteine were oxydized rapidly by Synechococcus m em brane fractions. Rates o f about 200 (imol o f cysteine oxydized per mg chlorophyll and hour were measured. This cysteine respiration is discussed in relation to dark inactivation o f enzymes. 
  Reference    Z. Naturforsch. 38c, 446—450 (1983); received February 22 1983 
  Published    1983 
  Keywords    Cysteine Oxydation, Oxygen, Thiol Compounds, Synechococcus, Cyanobacteria 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0446.pdf 
 Identifier    ZNC-1983-38c-0446 
 Volume    38