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Enhanced incorporation of nonhydrolyzable tritium in GnRH and TRF by catalytic exchange labeling
Author(s) -
Oehlke J.,
Mittag E.,
Tóth G.,
Bienert M.,
Niedrich H.
Publication year - 1987
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.2580241211
Subject(s) - chemistry , tritium , histidine , amide , catalysis , ring (chemistry) , derivative (finance) , tritium illumination , specific activity , stereochemistry , radiochemistry , medicinal chemistry , organic chemistry , enzyme , physics , nuclear physics , financial economics , economics
Gonadotropin releasing hormone (GnRH), D‐Phe 6 ‐GnRH and thyrotropin releasing factor (TRF) were tritiated by direct catalytic exchange using Rh/Al 2 O 3 + HT under conditions which lead in model deuterations of Nα‐acetylhistidine amide to a high incorporation of deuterium into position 5 of the histidine ring. Specific activities up to a range of 400 GBq/mmol in form of nonhydrolyzable tritium are attainable after removal of the label incorporated into position 2 of the histidine ring. A crucial reason for diminished specific activities was found to be a catalystmediated hydrogen transfer between the peptides and traces of water, contained in the reaction mixture, competing with the tritiation.