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'Amino acids' in keywords Facet   Publication Year 1979  [X]
Facet   section ZfN Section C  [X]
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1979[X]
1Author    BenjaminF. Matthews, JackM W IdholmRequires cookie*
 Title    Expression of Aspartokinase, Dihydrodipicolinic Acid Synthase and Homoserine Dehydrogenase During Growth of Carrot Cell Suspension Cultures on Lysine-and Threonine-Supplemented Media  
 Abstract    Reduction in the amounts o f activity o f the first enzyme, aspartokinase (EC 2.7.2.4) and two branch-point enzymes, dihydrodipicolinic acid synthase (EC 4.2.1.52) and homoserine dehydrogen­ ase (EC 1.1.1.3), located in the pathway for the synthesis o f aspartate-fam ily am ino acids, oc­ curred when cell suspension cultures of Daucus carota L. var. Danvers were grown in media contain­ ing 2 m M threonine or 2 m M lysine, endproducts of the pathway. Activity o f the lysine-sensitive form of aspartokinase was decreased when cells were grown in medium containing lysine and the ac­ tivity of the threonine-sensitive form was decreased when cells were grown in m edium containing threonine. Activity o f the branch-point enzyme leading to threonine synthesis, hom oserine dehy­ drogenase, was decreased up to 70% in specific activity (units/m g protein) and relative activity (units/g fresh weight) when cells were grown in m edia containing lysine or threonine. Threonine had no effect on the relative activity of dihydrodipicolinic acid synthase, but decreased its specific activity. Lysine decreased the relative activity of the synthase by up to 40%, but had little effect on its specific activity. The decreased activities o f the enzymes were apparently not due to binding of the inhibitory amino acids to the enzymes since homogenization of cells in buffer with 2 m M lysi­ ne and threonine did not decrease the m easurable enzyme activities. These and other results pres­ ented suggest that both forms of the aspartokinase activity and homoserine dehydrogenase activi­ ty can be altered by supplementing the growth medium with lysine or threonine. 
  Reference    Z. Naturforsch. 34c, 1177—1185 (1979); received June 18 1979 
  Published    1979 
  Keywords    Daucus carota, Suspension Cultures, Amino Acids, Enzyme Regulation 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1177.pdf 
 Identifier    ZNC-1979-34c-1177 
 Volume    34 
2Author    Wilhelm Simonis, Johanna Lee-KadenRequires cookie*
 Title    Selektive  
 Abstract    Wirkungen von Lindan (y-l,2,3,4,5,6-Hexachlor-cyclohexan) auf Photosynthese, Aminosäure — Membrantransport und Proteinsynthese bei Anacystis nidulans Selective Effects of Lindane (7-1,2,3,4,5,6 Hexachlorocyclohexane) on Photosynthesis, M embrane Transport of Amino Acids and Protein Synthesis in Anacystis nidulans Effects of the chlorinated hydrocarbon insecticide Lindane on membrane transport of two neu­ trale amino acids in the Cyanobacterium Anacystis nidulans (Synechococcus AN) were measured. In white light the L-Leucine incorporation into the protein fraction was inhibited, increasing with time. After 30 minutes the degree of inhibition was the same as the effect of DCMU (5X 10-6 m) on L-Leucine incorporation. 14C 02-fixation was also reduced at this time. At 717 nm, which en­ ables PS I activity allone, no inhibition was observed. The light energy dependent membrane transport itself of L-leucine in presence of CAM and of the non-metabolisable a-AIB in white light and in monochromatic light of 630 nm and of 717 nm were not influenced by Lindane. The different sites of Lindane action are discussed. It is assumed that in 30 minutes chiefly photo­ synthesis (PS II and C 02-fixation) is affected by Lindane, resulting in a suppression of protein synthesis caused by a depletion of intermediates of C 02-fixation. 
  Reference    Z. Naturforsch. 34c, 1062—1065 (1979); eingegangen am 12. Juni 1979 
  Published    1979 
  Keywords    Anacystis nidulans, Lindane Effects, Amino Acids, Membrane Transport, Photosynthesis 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-1062.pdf 
 Identifier    ZNC-1979-34c-1062 
 Volume    34