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'Ascorbate Peroxidase' in keywords Facet   section ZfN Section C  [X]
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1999 (1)
1991 (1)
1Author    A. Kira, W. Adano3, MitsuharuA. Zeta3, Shin-Ichi Itotani3, Ai Kanda3, Toshio Iwaki3, Tom Oaki Tairab, YasushiF. Ujiib, Yoshifumi Nishiurac, HaruhikoM. Urasec, Nobuo HonamRequires cookie*
 Title    Change of Ascorbic Acid Level after Grafting of Tomato Seedlings  
 Abstract    Grafting is an easy way to produce a new seedling, which can tolerate against various stresses. During the acclimation after grafting, however, the seedlings still suffer a severe water stress. It is well known that water stress produces active oxygen to oxidize ascorbic acid. The concentration of ascorbic acid in the leaves was analyzed by HPLC equipped with an electrochemical detector. The column used was SP-120-5-O D S-BP (DAISO, JAPAN) and elution was performed with 0.1 m phosphate buffer, pH 3.0. After grafting the seedlings were acclimated under a 6-hr light/dark regimen. The content of ascorbic acid increased gradually during 2 days compared with control. The ascorbate peroxidase showed about constant activity, so the increase of ascorbic acid may be due to its requirement to cure the grafting. 
  Reference    Z. Naturforsch. 54c, 830—8 (1999); receivced December 20 1998/February 3 1999 
  Published    1999 
  Keywords    Ascorbate Peroxidase, Ascorbic Acid, Glutathione, Grafting, Water Stress 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0830.pdf 
 Identifier    ZNC-1999-54c-0830 
 Volume    54 
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