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Tritium labelling of two highly selective agonists for CCK‐B receptor: [ 3 H]propionyl‐Tyr(SO 3 Na)‐gNle‐mGly‐Trp‐(N‐Me)Nle‐Asp‐Phe‐NH 2 ([ 3 H]pBC 264) [ 3 H]propionyl‐γDLys‐Trp‐Nle‐Asp‐Phe‐NH 2 ([ 3 H]pBC 254)
Author(s) -
Corringer P. J.,
Durieux C.,
RuizGayo M.,
Roques B. P.
Publication year - 1992
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.2580310606
Subject(s) - chemistry , receptor , agonist , propionate , in vivo , stereochemistry , tritium , ligand (biochemistry) , in vitro , biochemistry , physics , microbiology and biotechnology , nuclear physics , biology
Among the CCK‐B receptor agonists reported to date, the two modified peptides BC 264 and BC 254 display a high affinity and selectivity for this binding site and are highly protected from enzymatic degradation. Recently, we reported the biological properties of a tritiated analog of this agonist, [ 3 H]pBC 264, which fullfils all the criteria required for in vitro as well as in vivo studies of the CCK‐B receptor. On the other hand, BC 254 displays a high affinity for the CCK‐B binding sites in the guinea‐pig (K 1 = 0.56 nM) while its affinity in the rat is more than 60‐fold lower, a difference which could be due to the occurrence of CCK‐B receptor subtypes. In the present paper, we report the synthesis of [ 3 H]pBC 264 and of the new tritiated ligand [ 3 H]pBC 254 using [ 3 H] NPS (N‐succinimidyl[2,3‐ 3 H]propionate) as labelling agent. These two probes have high specific activity (70–100 Ci/mmol) and will enable extensive studies of the CCK‐B receptors to be carried out.