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1980 (2)
1979 (1)
1Author    M. Wink, T. Hartmann, L. WitteRequires cookie*
 Title    Enzymatic Synthesis of Quinolizidine Alkaloids in Lupin Chloroplasts  
 Abstract    The enzymatic sequence responsible for the biosynthesis o f tetracyclic quinolizidine alkaloids could be localized in chloroplasts isolated from Lupinus polyphyllus leaves and L. albus seedlings by differential centrifugation. U pon feeding of cadaverine to isolated chloroplasts lupanine is produced as the m ain alkaloid. Chloroplasts treated with digitonine produce sparteine and 17-oxosparteine instead o f lupanine, thus indicating that the biosynthetic sequence is interrupted. The intermediacy of 17-oxosparteine could be confirmed since exogeneous 17-oxosparteine is con­ verted into lupanine by intact chloroplasts. 17-Oxosparteine synthase (see Z. N aturforsch. 34 c, 704 1979) the key enzyme of quinolizidine alkaloid biosynthesis could be solubilized from chloro­ plasts treated with detergents or osmotic shock. 
  Reference    Z. Naturforsch. 35c, 93—9 (1980); received Septem ber 26 1979 
  Published    1980 
  Keywords    Quinolizidine Alkaloids, Enzymatic Synthesis, Isolated Chloroplasts, Lupinus polyphyllus 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0093.pdf 
 Identifier    ZNC-1980-35c-0093 
 Volume    35 
2Author    H. Ans-M, Artin SchiebelRequires cookie*
 Title    A Model Mechanism for the Enzymatic Synthesis of Lupin Alkaloids  
 Abstract    A crude enzyme preparation obtained from cell suspension cultures o f Lupinus polyphyllus cat­ alyzes the pyruvate dependent conversion o f cadaverine into the tetracyclic lupin alkaloids. As the first reaction product 17-oxosparteine could be identified by gas-liquid chrom atography and mass spectroscopy. In som e experiments sparteine was found additionally. A participation o f di­ amine oxidase could be ruled out. The cadaverine-pyruvate transaminating enzyme system (17-oxosparteine synthase) catalyzes the formation o f 17-oxosparteine from three cadaverine units without releasing free intermediates. These results are inconsistent with the hypothetical m echa­ nism thus far formulated for the lupin alkaloid biosynthesis. A new enzym atic model mechanism is proposed regarding both the results o f the enzymatic experiments and those o f the in vivo tracer studies. 
  Reference    Z. Naturforsch. 34c, 704—708 (1979); received June 8 1979 
  Published    1979 
  Keywords    Lupinus polyphyllus, Cell Suspension Cultures, Q uinolizidine Alkaloids, Enzymatic Synthesis, Biosynthetic Model Mechanism 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0704.pdf 
 Identifier    ZNC-1979-34c-0704 
 Volume    34 
3Author    C. Sauer, U. SchwabeRequires cookie*
 Title    M ethod for the Selective 2 '-0 -S u b stitu tio n o f N ucleosides  
 Abstract    This paper presents a new method for selective reactions o f predetermined sugar hydroxyls o f nucleosides. Suc-cinylated nucleosides were investigated as examples for the use of the cyclic phosphate group for protecting purposes. Starting from cyclic AMP the 2'-0-group was selectively succinylated yielding 93% 2'-0-succinyl cyclic AMP. The cyclic phosphate was enzymatically dephosphorylated in a one step procedure under neutral conditions and 2 '-0 -suc-cinyl adenosine containing a small amount o f the 3'-0-isomer was produced in 91% yield. When establishment of equilibrium of the 2'-0-and 3'-0-isomers was allowed, 54% yield of crystallized 3'-0-succinyl adenosine was prod­ uced. The results suggest that the easily accessible cyclic monophosphates are good protecting groups for the pro­ duction of nucleoside derivatives, especially at the 2 '-0 -position under neutral conditions. 
  Reference    Z. Naturforsch. 35c, 163—167 (1980); received June 15/September 21 1979 
  Published    1980 
  Keywords    Cyclic AMP, Enzymatic Synthesis, Cyclic Phosphate as Protection Group, 2'-0-Succinyl Adenosine, 2'-0-Substitu-tion o f Nucleosides 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0163_n.pdf 
 Identifier    ZNC-1980-35c-0163_n 
 Volume    35