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1991[X]
1Author    Elisabeth Häusler, Maike Petersen, AugustW. AlfermannRequires cookie*
 Title    Hydroxyphenylpyruvate Reductase from Cell Suspension Cultures of Coleus blumei Benth  
 Abstract    Cell suspension cultures o f Coleus blumei Benth. producing high amounts o f rosmarinic acid were used to study the biosynthetic pathway o f this caffeic acid ester. One o f the involved en­ zymes, the hydroxyphenylpyruvate reductase (H PPR), is characterized in this paper. HPPR catalyzes the N A D (P)H dependent reduction o f /^-hydroxyphenylpyruvate to /»-hydroxyphen-yllactate. The enzyme developed maximal activity at an incubation temperature o f 37 °C and at a pH o f 6.5 to 7.0. The reaction proceeded linearly for an incubation time o f 60 min and up to a protein concentration o f 0.2 mg per assay. As electron donor HPPR accepted N A D H and N A D P H with A^m-values o f 190 jim and 95 |im respectively. The enzyme reduced differently substituted hydroxyphenylpyruvates but not ß-phenylpyruvate. The apparent A^m-values for the various substrates were at 10 for /^-hydroxyphenylpyruvate, at 130^xm for 3,4-dihy-droxyphenylpyruvate and at 250 |iM for 3-methoxy-4-hydroxyphenylpyruvate. HPPR was com petitively inhibited by rosmarinic acid and pyruvate with /^-values o f 210 |iM and 200 |IM respectively. Caffeic acid,/>-coumaric acid and cinnamic acid did not affect the enzyme activity but/>-coumaroyl-CoA inhibited HPPR. 
  Reference    Z. Naturforsch. 46c, 371—3 (1991); received January 21 /February 26 1991 
  Published    1991 
  Keywords    Coleus blumei, Lamiaceae, Cell Suspension Culture, Biosynthesis, Rosmarinic Acid 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0371.pdf 
 Identifier    ZNC-1991-46c-0371 
 Volume    46