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1991 (1)
1989 (1)
1Author    W. Bilger, U. SchreiberRequires cookie*
 Title    Modulation of Millisecond Chlorophyll Luminescence by Non-Photochemical Fluorescence Quenching  
 Abstract    By combining a high frequency modulation system for measurement of fluorescence with a phosphoroscope type apparatus for measurement of luminescence, recordings of fluorescence and luminescence induction kinetics under identical conditions were obtained. Both measuring sys­ tems tolerated the application of saturating pulses of white light for rapid, transient elimination of photochemical quenching at photosystem II reaction centers, thus allowing determination of the non-photochemical quenching component. The saturation pulse induction curves of luminescence are well correlated with the corresponding curves of fluorescence, suggesting that luminescence yield is lowered by the same type of non-photochemical quenching (mostly "energy dependent quenching") as fluorescence. Hence, in order to evaluate luminescence signals in terms of the rate of charge recombination at photosystem II reaction centers, knowledge of fluorescence quenching is required. 
  Reference    Z. Naturforsch. 44c, 966 (1989); received June 28 1989 
  Published    1989 
  Keywords    Chlorophyll Luminescence, Chlorophyll Fluorescence, Energy Dependent Quenching, Photo­ system II, Photosynthesis Induction 
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 TEI-XML for    default:Reihe_C/44/ZNC-1989-44c-0966.pdf 
 Identifier    ZNC-1989-44c-0966 
 Volume    44 
2Author    U. Lrich Schreiber, H. Einz, Reising, C. Hristian, N. EubauerRequires cookie*
 Title    Contrasting pH-Optima of Light-Driven 0 2-and H 20 2-Reduction in Spinach Chloroplasts as Measured via Chlorophyll Fluorescence Quenching  
 Abstract    Quenching analysis o f chlorophyll fluorescence by the saturation pulse method is used to investigate the pH-dependency o f 0 2-dependent electron flow in intact spinach chloroplasts with high ascorbate peroxidase activity. When carboxylase/oxygenase activity is blocked, p h o­ tochem ical and non-photochemical quenching are initially low and increase with illumination time. Quenching shows a pH-optimum around pH 6.5, but only when ApH-formation is al­ lowed. It is suggested that overall 0 2-dependent electron flow involves two major com ponents, namely 0 2-reduction (M ehler reaction) and reduction o f the H 20 2 formed in the Mehler reac­ tion, involving enzymic activity o f ascorbate peroxidase and m onodehydroascorbate reduc­ tase. The separated pH-dependencies o f light driven 0 2-reduction (presence o f K C N) and o f H 20 2-reduction (anaerobic conditions) reveal contrasting pH-optim a around pH 5 and 8.5, re­ spectively. Energy-dependent, dark relaxable non-photochem ical quenching is not observed with 0 2-reduction but with H20 2-reduction, and only at pH-values above 6.5. The relevance o f these findings with respect to regulation o f photosynthetic electron flow is discussed. It is sug­ gested that upon limitation o f assimilatory electron flow 0 2-dependent non-assim ilatory flow is responsible for ApH-formation, by which it is autocatalytically stimulated. It is proposed that this autocatalytical reaction sequence is the basis o f the so-called "Kautsky effect" o f chlorophyll fluorescence induction. 
  Reference    Z. Naturforsch. 46c, 635 (1991); received March 6 1991 
  Published    1991 
  Keywords    Chlorophyll Fluorescence, Mehler Reaction, Ascorbate Peroxidase, Energy Dependent Quenching, Photosynthesis Regulation 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0635.pdf 
 Identifier    ZNC-1991-46c-0635 
 Volume    46