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'Glucuronidierung UDP Glucuronyl Transferase' in keywords Facet   section ZfN Section B  [X]
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1972 (1)
1Author    Herbert Schriefers, Rüdiger Ghraf, Birgit LehnenRequires cookie*
 Title    stendion-Verbindungen durch die mikrosomale UDP-Glucuronyl- Transferase der Rattenleber Glucuronidation of Hydroxy-compounds of Testosterone and Androstenedione by the Microsomal UDP Glucuronyl Transferase of Rat Liver  
 Abstract    The microsomal UDP glucuronyl transferase exhibits activities against hydroxy derivatives of androstenedione (hydroxyl groups in the positions 2/?, 6ß or 16a) between 5% and 21% of the extent shown against testosterone. 2ß-, 6ß-and 16a-hydroxyl groups are much less efficient in ac-cepting the glucuronic acid than the 17/Miydroxyl group. However, the acceptor function of the 17/?-hydroxyl group is restricted by other hydroxy sub-stituents in the testosterone molecule to an increasing extent represented by the following sequence: 2a, 6ß, 6a, 16a, and 7a. A special case is represented by 2/?-hydroxy-testosterone. The transferase displays a higher activity against this compound than against testosterone. Apparently the transferase approaches the steroid molecule from the a-side (with the /?-side there is also contact at the C-6 atom) requires the 17/?-hydroxyl group and the 3-oxo-4-ene system to display full activity. Thus the very high specificity of the transferase for testosterone explains the selective action of this enzyme on testosterone metabolism in the liver. This action is expressed by the fact, that in liver perfusates the percentage of testosterone in the glucuronide fraction is twice as large as the percentage of testosterone in the free steroid fraction. 
  Reference    (Z. Naturforsch. 27b, 49—52 [1972]; eingegangen am 13. August 1971. revidiert am 7. November 1971) 
  Published    1972 
  Keywords    Hydroxy-testosteron, Hydroxy-androstendion, Glucuronidierung UDP-Glucuronyl-Transferase, Substratspezifität 
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 TEI-XML for    default:Reihe_B/27/ZNB-1972-27b-0049.pdf 
 Identifier    ZNB-1972-27b-0049 
 Volume    27