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Specific tritiation onto C‐2 and C‐5 positions of histidine ‐ containing peptide. Application to thyroliberin
Author(s) -
LevinePinto H.,
Pradelles P.,
Morgat J. L.,
Fromageot P.
Publication year - 1980
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.2580170210
Subject(s) - chemistry , tritium , iodine monochloride , imidazole , histidine , hydrogenolysis , labelling , catalysis , residue (chemistry) , peptide , specific activity , tritium illumination , halogenation , radiochemistry , stereochemistry , iodine , organic chemistry , amino acid , biochemistry , enzyme , physics , nuclear physics
Specific methods of tritium labelling onto C‐2 and (or) C‐5 positions of the imidazole ring were successfully applied to thyroliberin (TRF, L‐Glu‐L‐His‐L‐Pro‐NH 2 ). Diazocoupling by diazotized sulphanilic acid and iodination by iodine monochloride of the histidyl residue were chosen to prepare precursors and to quantify the distribution of tritium atoms which were introduced. Catalytic hydrogenolysis in the presence of tritium gas of 5‐iodohistidine 2 ‐ and 2(4‐sulfophenylazo)histidine 2 ‐ derivatives allowed to label these positions with specific radioactivities of 30 Ci and 25 Ci/mmole respectively. For comparison thyroliberin tritiated by direct catalytic exchange is labelled essentially onto C‐2 with a specific radioactivity of 30 Ci/mmole.