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'Digitoxin 12ß Hydroxylase' in keywords
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1988 (1)
1Author    Maike Petersen, Ulrich Hanns, Seitz, Ernst ReinhardRequires cookie*
 Title    Characterization and Localization of Digitoxin 12 ß-Hydroxylase from Cell Cultures of Digitalis lanata EHRH  
 Abstract    The cytochrome P-450-dependent monooxygenase digitoxin 12ß-hydroxylase from cell cultures of Digitalis lanata needs NADPH and molecular oxygen and hydroxylates cardiac glycosides with the aglycon of digitoxigenin to the corresponding derivatives of the C-series. Other electron donors cannot replace NADPH. The apparent K" m -values are 26 UM for NADPH, 7.1 ^IM for ß-methyldigitoxin and 10 ^IM for digitoxin. The reaction is inhibited by NADP + and cytochrome c in a competitive mode. The optimum temperature was at 20 °C. Low concentrations of Mn 2+ , Mg 2+ , and EDTA were slightly stimulatory, but there was no strict dependence on divalent cations. Digitoxin 12ß-hydroxylase is very stable at room temperature and the reaction proceeds for more than 20 h. After the addition of 15% glycerol, 70% of the original activity can be retained subsequent to freezing at —18 °C. By means of linear sucrose gradient fractionation of cellular membranes the digitoxin 12ß-hydroxylase was found to be located in the endoplasmic reticulum. 
  Reference    Z. Naturforsch. 43c, 199—206 (1988); received December 8 1987 
  Published    1988 
  Keywords    Cardiac Glycosides, Cytochrome P-450, Digitalis lanata, Digitoxin 12ß-Hydroxylase, Endoplas-mic Reticulum 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0199.pdf 
 Identifier    ZNC-1988-43c-0199 
 Volume    43