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1990 (1)
1981 (2)
1Author    M. Anfred Steingraber, Hanns Frohnm, Rüdiger HamRequires cookie*
 Title    Light-Dependent Sucrose Synthesis in Cell-Free (Reconstituted) Lysates of Evacuolated Mesophyll Protoplasts  
 Abstract    Oat mesophyll protoplasts were evacuolated by centrifugation on a Percoll gradient and used as starting material for establishing a functional cell-free system. For this purpose evacuolated protoplasts were osm otically lysed. From the resulting homogenate a cytosolic fraction was obtained by silicon oil filtration. This fraction was used to dilute preparations o f lysed evacu­ olated protoplasts in order to reduce the number o f organelles per volume cytosol. The latter was necessary to increase light-dependent oxygen evolution o f the cell-free system. The result­ ing kind o f "reconstituted" system showed light-dependent sucrose formation (about 100 nmol (mg Chi)-1 • h r 1) with bicarbonate as the only substrate. As this property depends on a functional interaction o f chloroplast and cytosolic reactions, this cell-free system appeared to perform essential steps o f partitioning o f C 0 2 between starch and sucrose. Addition o f about 12 (im fructose 2 ,6 -bisphosphate, an inhibitor o f fructose 1,6 -bisphosphatase and an activator o f the PPi-dependent fructose 6 -phosphate phosphotransferase, caused sucrose degradation in the light. Thus, this cell-free system allows both the study o f cytosolic enzyme activities under quasi in vivo conditions and the manipulation o f cellular reaction sequences by plasma mem­ brane-impermeable compounds. 
  Reference    Z. Naturforsch. 45c, 217 (1990); received January 11 1990 
  Published    1990 
  Keywords    Avena sativa, Cell-Free System, Evacuolation, Mesophyll Protoplasts, Sucrose Synthesis 
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 TEI-XML for    default:Reihe_C/45/ZNC-1990-45c-0217.pdf 
 Identifier    ZNC-1990-45c-0217 
 Volume    45 
2Author    Wolfgang Knogge, Gottfried Weissenböck, Dieter StrackRequires cookie*
 Title    Application of Liquid Chromatography to a Study on 4-Coumarate: Coenzyme A Ligase Activity  
 Abstract    This report describes the separation of components from a 4-coumarate: CoA ligase assay by means of liquid chromatography. With the aid o f polyamide column chromatography it is possible to enrich and isolate chromatographically and UV spectroscopically pure /»-coumaroyl-CoA using as a solvent 0.01% N H 4OH in methanol subsequent to water and methanol alone. High performance liquid chromatography on octadecylsilane-bonded silica stationary phase allows a discontinuous determination o f ligase activity. All components — ATP, Coenzyme A, p-coumaric acid, and the products AMP and p-coumaroyl-CoA — can be separated and accurately quantified within 20 min using a water-acetonitrile gradient, containing 1% phosphoric acid. The presented HPLC method may be used to affirm the accuracy of optical tests. 
  Reference    Z. Naturforsch. 36c, 197—199 (1981); received December 91980 
  Published    1981 
  Keywords    Avena sativa, Poaceae, Ligase, /?-Coumaroyl-CoA, Polyamide Column Chromatography, High Performance Liquid Chromatography 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0197.pdf 
 Identifier    ZNC-1981-36c-0197 
 Volume    36 
3Author    Margareta Proksch, Dieter Strack, Gottfried WeissenböckRequires cookie*
 Title    Incorporation of [I4C]Phenylalanine and [14C|Cinnamic Acid into Leaf Pieces and Mesophyll Protoplasts from Oat Primary Leaves for Studies on Flavonoid Metabolism at the Tissue and Cell Level  
 Abstract    When the abaxial epidermis was peeled from 5 to 6 day old oat primary leaves, and 3 cm segments were floated on radioactive phenylalanine or cinnamic acid solutions, more than 90 per cent of the radioactivity was incorporated within 3 to 7 h depending on the developmental stage of the leaf. C-glycosylflavones were labelled within 15 min and radioactivity in these compounds increased for several hours. Pulse labelling and pulse chase experiments with either phenylalanine or cinnamic acid, unequivocally demonstrate that oat flavones are stable end products o f metabolism. However, this procedure does not distinguish between sequential biosynthesis of various flavones and their interconversion. Cinnamic acid was more efficiently (ca. 20 x) converted into oat leaf flavones than was phenylalanine, when the precursor was fed to leaf pieces, and flavones recovered from mesophyll protoplasts. Different labelling patterns were obtained with whole leaf segments and protoplasts which apparently reflect differences in tissue specific flavone biosynthesis o f mesophyll and epidermis. Isolated mesophyll protoplasts incubated with [14C]cinnamic acid synthesize 14C-labelled flavones characteristic o f the mesophyll, as well as several unidentified phenylpropanoid derivatives not found in the intact tissue. Data suggest that photosynthetically active mesophyll cells are a main site o f tissue specific flavone biosynthesis. 
  Reference    Z. Naturforsch. 36c, 222 (1981); received January 141981 
  Published    1981 
  Keywords    Avena sativa, Primary Leaf Tissues, Protoplasts, [14C]Phenylpropanoid Incorporation, C-Glycosyl-flavones 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-0222.pdf 
 Identifier    ZNC-1981-36c-0222 
 Volume    36