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'Quercetin' in keywords Facet   Publication Year 1985  [X]
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1985[X]
1Author    Kim Thresh, RagaiK. IbrahimRequires cookie*
 Title    Are Spinach Chloroplasts Involved in Flavonoid O-Methylation?  
 Abstract    Intact spinach chloroplasts, which were isolated on a cushion of Percoll and purified on discon­ tinuous sucrose gradients, were found to adsorb appreciable amounts of high specific activity, cytosolic O-methyltransferases. The latter activity was readily eliminated after washing the chloroplast pellet with 0.1 m phosphate in sucrose gradient buffer and finally with 0 .1% nonidet. Furthermore, the OMT activity of spinach leaves was resolved by chromatography on DEAE-Sepharose CL-6B into caffeic acid (COMT) and flavonoid (FOMT) O-methyltransferase ac­ tivities, and purified to 30-and 50-fold, respectively. The similarities between the FOMT/COMT activity ratios and the methylation patterns of intact chloroplasts and their supernatants, as well as those of purified leaf preparations, suggest non-specific binding of cytosolic OMTs to chloroplast envelopes. It is concluded, therefore, that spinach chloroplasts are not involved in the methylation of phenylpropanoid or flavonoid compounds. These results call attention for the re-evaluation of the role of this organelle in the biosynthesis or accumulation of plant secondary metabolites. 
  Reference    Z. Naturforsch. 40c, 331 (1985); received December 11 1984/February 26 1985 
  Published    1985 
  Keywords    Spinacea oleracea, Chenopodiaceae, Chloroplasts, O-Methyltransferase, Caffeic Acid, Quercetin 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0331.pdf 
 Identifier    ZNC-1985-40c-0331 
 Volume    40