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'Carbohydrate M etabolism' in keywords Facet   Publication Year 1991  [X]
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1Author    Abteilung Zellchemie, G.S FRequires cookie*
 Title    Activities and Regulation of Enzymes of Carbohydrate Metabolism in Spruce ( Picea abies) M einrad Boll  
 Abstract    Activities o f the glycolytic enzymes were determined in seedlings, callus cultures and cell sus­ pension cultures o f spruce (Picea abies) (L.) (Karst). The rate-limiting enzymes o f the pathway were the hexokinases, ATP: phosphofructo-kinase, fructose-1,6-bisphosphatase and pyruvate kinase. Two phosphofructokinases were found: A T P : fructose-6-phosphate 1-phosphotransferase (PFK) and pyrophosphate :fructose-6-phosphate 1-phosphotransferase (PFP). In the presence o f its activator fructose-2,6-bisphos-phate, PFP had a 4 -5-fold higher specific activity than PFK. PFP could be activated about 20-fold by fructose-2,6-bisphosphate at saturating concentrations o f the substrates (fructose-6-phosphate and pyrophosphate). The increase o f Fmax was accompanied by a strong increase in the apparent affinity o f the enzyme for the substrates. Km for fructose-6-phosphate and pyrophosphate was 0.44 mM and 24 fiM, respectively. Ka for fructose-2,6-bisphosphate was 24 nM. In seedlings, specific activity o f the glycolytic enzymes was 3 0 -3 0 0 percent higher in the hypocotyls, except for fructose-1,6-bisphosphate aldolase, glyceraldehyde-3-phosphate de­ hydrogenase and phosphoglycerate kinase, their activity being 1 0 0 -150 percent higher in the cotyledons, This distribution remained unchanged during periods o f 2 -16 weeks o f cultiva­ tion o f the seedlings. In callus cultures and in cell suspension cultures, grown mixotrophically with different car­ bohydrates, all enzymes were between 1-and 7-fold higher than in autotrophically grown seed­ lings. Incubation o f seedlings in mineral salt mixture containing a carbohydrate resulted in a rapid coordinate increase o f the activities to the levels o f callus-or cell suspension cultures. This induction required a carbohydrate and oxygen. During prolonged cultivation o f cell sus­ pension cultures, when carbohydrate became limiting, activity o f the enzymes slowly declined. 
  Reference    Z. Naturforsch. 46c, 597 (1991); received Dezember 7 1990/April 4 1991 
  Published    1991 
  Keywords    Picea abies, Cell Culture, Carbohydrate M etabolism, PP, -phosphofructokinase, Enzyme Regulation 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0597.pdf 
 Identifier    ZNC-1991-46c-0597 
 Volume    46