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Preparation of specifically tritiated endomorphins
Author(s) -
Tömböly Csaba,
Dixit Rajiv,
Lengyel Imre,
Borsodi Anna,
Tóth Géza
Publication year - 2001
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.463
Subject(s) - chemistry , tritium , tetrapeptide , receptor , ligand (biochemistry) , specific activity , stereochemistry , labelling , μ opioid receptor , halogenation , peptide , biochemistry , opioid , enzyme , organic chemistry , physics , nuclear physics
Abstract Endomorphin‐1 (EM1, Tyr‐Pro‐Trp‐Phe‐NH 2 ) and endomorphin‐2 (EM2, Tyr‐Pro‐Phe‐Phe‐NH 2 ) are natural tetrapeptide ligands of µ‐opioid receptors involved in the modulation and attenuation of pain. For a detailed examination of their receptor‐binding properties and their metabolic stability, tritium‐labelled EM1 and EM2 radioisotopomers were synthesized by catalytic dehalogenation or saturation of the precursor peptides with tritium gas. Amino acid analysis revealed that the tritium labelling was specific and the specifically labelled radioligands possessed high specific activity, ranging from 0.77 TBq/mmol to 2.35 TBq/mmol. The biological half‐lives of the peptides in the biological matrix (295 min and 230 min for EM1 and EM2, respectively) indicate that these radioligands are appropriate for binding assays in rat brain membrane preparations. The radioisotopomers of EM2 are not statistically different in the receptor‐ligand interaction, and they are excellent tools for further comparative biochemical studies. Copyright © 2001 John Wiley & Sons, Ltd.