Go toArchive
Browse byFacets
Bookbag ( 0 )
'Photooxidation' in keywords
Results  9 Items
Sorted by   
Publication Year
1986 (1)
1984 (1)
1982 (2)
1980 (1)
1979 (3)
1976 (1)
1Author    Hans). Brockmann, Clemens Und, BelterRequires cookie*
 Title    Regioselektive Ringspaltung von Bacteriochlorophyll-Derivaten durch Photooxidation Regioselective Ring Cleavage of Bacteriochlorophyll Derivatives by Photooxidation  
 Abstract    In the presence of oxygen and light magnesium free derivatives of bacteriochlorophyll c form linear tetrapyrroles by oxidative ring cleavage. The structure of these photobilines has been determined by spectroscopic methods. c2H5 
  Reference    (Z. Naturforsch. 34b, 127—128 [1979]; eingegangen am 21. Oktober 1978) 
  Published    1979 
  Keywords    Bacteriochlorophyll Derivatives, Photooxidation, Regioselective Ring Cleavage 
  Similar Items    Find
 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0127_n.pdf 
 Identifier    ZNB-1979-34b-0127_n 
 Volume    34 
2Author    Nikolaus Risch, Clemens BelterRequires cookie*
 Title    Chemischer Strukturbeweis für Photobilin c und ein Beitrag zu seinem Bildungsmechanismus Chemical Structure Determination for Photobilin c and a Contribution to the Formation Mechanism  
 Abstract    The structure of photobilin c is determined by oxidative degradation of 18 0-labeled material which is prepared by photooxidation of a deriva-tive of bacteriochlorophyll c in the presence of molecular 18 02. 
  Reference    (Z. Naturforsch. 34b, 129—130 [1979]; eingegangen am 21. Oktober 1978) 
  Published    1979 
  Keywords    Photooxidation, Photobilin c, Structure, 18 0-Isotopic-Labeling 
  Similar Items    Find
 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0129_n.pdf 
 Identifier    ZNB-1979-34b-0129_n 
 Volume    34 
3Author    Günter LazarRequires cookie*
 Title    Light-Induced Valence Change of a Manganese-Containing Chlorophyll Derivative  
 Abstract    K3(Mn-(III)-chlorin e6) acetate, a water-soluble chlorophyll derivative with manganese as central atom was prepared. The influence o f reducing agents, light, and bicarbonate on the oxida­ tion states of manganese in the chlorin complex was investigated. In alkaline solutions the central Mn3+ was reducible to Mn2+. The illumination of the partially reduced complex first accelerated the reduction (light reduction: Mn3+ -> Mn2+), which was then followed by a strong reoxidation (light oxidation: Mn2+ -* Mn3+) continuing after switching off the light. This redox effect o f light was obtained only in presence o f hydroxylamine as reducing agent. Illumination time, intensity, and frequency had an influence on this effect. In the light/dark change the process was reversible. In regard to the requirement of manganese for the photosynthetic oxygen evolution the observed valence change o f manganese in the chlorin complex was compared to the supposed reaction mechanism on the donor side o f photosystem II. 
  Reference    Z. Naturforsch. 35c, 470—476 (1980); received December 17 1979/March 19 1980 
  Published    1980 
  Keywords    Mn-(III)-chlorin, Photosynthesis, Photoreduction, Photooxidation, Hydroxylamine 
  Similar Items    Find
 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0470.pdf 
 Identifier    ZNC-1980-35c-0470 
 Volume    35 
4Author    Georg SchmettererRequires cookie*
 Title    Formation of Hydrocarbons by Photobleaching Cyanobacterium, A nacystis nidulans  
 Abstract    The cyanobacterium Anacystis nidulans is bleached when subjected to both light and 0 2 to­ gether with suitable (pre)treatment o f the cells such as incubation at high (^ 4 8 °C) or low (S 17 °C) temperatures, or in presence o f metabolic inhibitors, or o f substances forming com­ plexes with divalent cations. Concomitantly degradation o f the intracellular membranes is ob­ served (G. Schmetterer, G. A. Peschek, Biochem. Physiol. Pflanzen 176, 9 0 —100 (1981)). The same three conditions cause formation o f hydrocarbons, mostly ethane, a characteristic product of lipid peroxidation. Ethane production is unchanged and still light-sensitive even when no more pigments can be detected in the cells. In "white" cells light-dependent 0 2-uptake is also observed. The action spectrum of this process suggests that "completely" bleached cells retain very small amounts of residual chlorophyll, which must be unusually resistant to photooxidation. 
  Reference    Z. Naturforsch. 37c, 205 (1982); received November 51981 
  Published    1982 
  Keywords    Photooxidation, Ethane Production, Cyanobacterium, Anacystis nidulans, Lipid Peroxidation 
  Similar Items    Find
 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0205.pdf 
 Identifier    ZNC-1982-37c-0205 
 Volume    37 
5Author    Jürgen Feierabend, TheresiaW. Inkelhüsener, Petra Kemmerich, Ulrike SchulzRequires cookie*
 Title    Mechanism of Bleaching in Leaves Treated with Chlorosis-Inducing Herbicides  
 Abstract    Bleaching o f chlorophyll was studied in the leaves of rye seedlings (Secale cereale L.) treated with four chlorosis-inducing herbicides of different potency (weak photodestructions, group 1: aminotriazole, haloxidine; strong photodestructions, group 2: San 6706, difunone). Chlorophyll deficiency and particularly the inactivation of a chloroplast marker enzyme, NADP-dependent glyceraldehyde-3-P dehydrogenase, that occurred in the presence o f group 2 herbicides were stronger in red, than in blue, light. When grown in white light o f low intensity (10 lx) herbicide-treated leaves contained chloro­ phyll, 70 S ribosomes and unimpaired activities o f NADP-dependent glyceraldehyde-3-P de­ hydrogenase. At 10 lx only the leaves treated with SAN 6706 and difunone were strongly carotenoid-deficient but not those treated with group 1 herbicides. After all herbicide treatments 10 lx-grown leaf tissue was, however, not capable o f photosynthetic 0 2-evolution indicating some disorder of photosynthetic electron transport. Leaf segments grown at 10 lx were exposed to a high light intensity o f 30000 lx at either 0 ° C or 30 °C. In treatments with group 1 herbicides chlorophyll accumulation was stopped in bright light at 30 °C but breakdown was not apparent. Only at 0 °C and in the presence of high, growth-reducing, herbicide concentrations chlorophyll was slightly degraded. The RNAs o f the 70S ribosomes were, however, clearly destroyed at 30000 lx and 30 °C in aminotriazole-treated leaves. In leaves treated with group 2 herbicides chlorophyll was rapidly degraded at 30000 lx both at 0 ° C and 30 °C, however, only in the presence of 0 2, indicating a true photooxidative and mainly photochemical nature o f the reactions involved. This chlorophyll breakdown was accompanied by the photodestruction of 70S ribosomes and the inactivation of NADP-glyceraldehyde-3-P dehydrogenase. In treatments with group 1 herbicides photoinactivation o f the latter enzyme did not occur, although it was clearly localized in the bleached plastids, as demonstrated by gradient separation o f organelles. In the presence of group 2 herbicides the chlorosis was originating from a direct photo­ oxidation of chlorophyll, accompanied by a massive destruction o f other plastid constituents and functions. In treatments with group 1 herbicides photodestructions appeared to be much weaker and insufficient to affect chlorophyll directly. Mediated through some photodestructive inter­ ference with obviously more sensitive plastid components, such as their ribosomes, further chlorophyll accumulation was, however, prevented. 
  Reference    Z. Naturforsch. 37c, 898 (1982); received July 7 1982 
  Published    1982 
  Keywords    Bleaching Herbicides, Carotenoids, Chlorophyll, Photooxidation, Plastid rRNA 
  Similar Items    Find
 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0898.pdf 
 Identifier    ZNC-1982-37c-0898 
 Volume    37 
6Author    ThorB. Melø, Gro ReisaeterRequires cookie*
 Title    Photodestruction of Endogenous Porphyrins in Relation to Cellular Inactivation of Propionibacterium acnes  
 Abstract    of Propionibacterium acnes on Eagles medium protoporphyrin was accumulated inside the cells and coproporphyrin, both as a free base as metalcontaining, outside the cells. The photochemical processes in the endogenous porphyrins were studied by fluorescence spectroscopy during continuous irradiation of Propionibacterium acnes in suspension. The irradiation caused initially an increase in the content of protoporphyrin in the cells in comparison to that which had been accumulated during growth. Maximum light induced protoporphyrin production was achieved in 5 days old cultures. In old cultures where there was practically no initial protoporphy­ rin release, the fluorescence intensities from all the porphyrins present in the culture vanished exponentially with the irradiation time. The metal containing form of fluorescent coproporphyrin, with a maximum emission at 580 nm, was photobleached about ten times faster than the free base forms of coproporphyrin and protoporphyrin. Among these three fluorescent substances in the cell culture only the free base forms of the porphyrins have longer lifetimes than the cells themselves irradiated at the same conditions. 
  Reference    Z. Naturforsch. 41c, 867 (1986); received February 28/June 3 1986 
  Published    1986 
  Keywords    Propionibacterium acnes, Porphyrins, Photooxidation, Fluorescence, Survival During growth 
  Similar Items    Find
 TEI-XML for    default:Reihe_C/41/ZNC-1986-41c-0867.pdf 
 Identifier    ZNC-1986-41c-0867 
 Volume    41 
7Author    Jürgen FeierabendRequires cookie*
 Title    Comparison of the Action of Bleaching Herbicides  
 Abstract    Among chlorosis-inducing herbicides that interfere with carotenoid synthesis two groups o f different potency can be discriminated (group 1; aminotriazole amd haloxidine; group 2 with more extensive photodestructions: pyridazinone herbicides and difunon). After application o f herbicides o f group 2 colored carotenoids were com pletely absent and preexisting chlorophyll was degraded by photochem ical reactions requiring high light intensity and 0 2, that occurred also at 0 °C . In treatments with group 1 herbicides direct photodegradation o f chlorophyll was not sufficient to generate the chlorosis. Light-induced interference with constituents o f the chloroplast protein synthesis apparatus being more sensitive to ph otooxidative dam age than chlorophyll, appeared to indirectly m ediate the chlorosis. In the absence o f chloroplast protein synthesis further chlorophyll accum ulation is prevented. Photodegradation o f chlorophyll in the presence o f group 2 herbicides involved the participation o f 0 2~ radicals and was accom panied by lipid peroxidation. In all herbicide treatments the catalase activity o f the leaves was very low. Only in the presence o f group 2 herbicides chloroplast enzym es o f cytoplasm ic origin (e.g. NADP-glyceraldehyde-3-phosphate dehydrogenase) were also inactivated. Rapid inactivation o f catalase as well as o f N A D P-glyceraldehyde-3-phosphate dehydrogenase was induced by exposure o f dim-light-grown herbicide-treated leaves to bright light, also at 0 ° C . In treatments with herbicides o f group 2 also other peroxisom al enzymes (e.g. glycolate oxidate, hydroxy-pyruvate reductase) were affected. The elim ination o f these peroxisom al enzym es also appeared to depend on photooxidative processes o f the chloroplast. 
  Reference    Z. Naturforsch. 39c, 450 (1984); received N ovem ber 4 1983 
  Published    1984 
  Keywords    Bleaching Herbicides, Carotenoids, Catalase, Chlorosis, Leaf Peroxisom es, Photooxidation 
  Similar Items    Find
 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0450.pdf 
 Identifier    ZNC-1984-39c-0450 
 Volume    39 
8Author    Requires cookie*
  Reference    (Z. Naturforsch. 31b, 1436—1437 [1976]; eingegangen am 18. Juni 1976) 
  Published    1976 
  Keywords    Tetramethyl-l, 2-dioxa-4, 5-diazine, Photooxidation, Heterocycles, Luminol-Chemiluminescence 
  Similar Items    Find
 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-1436_n.pdf 
 Identifier    ZNB-1976-31b-1436_n 
 Volume    31 
9Author    Uwe Jürgens, Hans BrockmannRequires cookie*
 Title    Substituenteneinfiüsse auf die Geschwindigkeit der Photobilin-Bildung Substituent Effects upon the Rate of Photobilin Formation  
 Abstract    The structural requirements for the regioselective photochemical ring-opening of chlorin derivatives and the corresponding rate of formation of the pertinent photobilins are reported. The structure of one of the photobilins is verified by X-ray analysis. 
  Reference    Z. Naturforsch. 34b, 1026—1030 (1979); eingegangen am 30. März 1979 
  Published    1979 
  Keywords    Photooxidation, C-20-Substituted Chlorin Derivatives, Rate of Ring Cleavage, Structure, X-ray 
  Similar Items    Find
 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-1026.pdf 
 Identifier    ZNB-1979-34b-1026 
 Volume    34