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Synthesis of two S‐(methyl‐ 3 H)‐labelled enkephalins and S‐(methyl‐ 14 C)substance P
Author(s) -
Någren Kjeli,
Franzèn Henry M.,
Ragnarsson Ulf,
Långström Bengt
Publication year - 1988
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.2580250205
Subject(s) - chemistry , methyl iodide , liquid ammonia , sodium iodide , methylation , ammonia , iodide , sodium , medicinal chemistry , stereochemistry , nuclear chemistry , organic chemistry , biochemistry , gene
The synthesis of 3 H‐labelled Met‐enkephalin and Tyr‐D‐Ala‐Gly‐Phe‐Met‐NH 2 (DALA) and 14 C‐labelled Substance P (SP) from previously described, fully protected intermediates is reported. The labelled peptides were prepared by methylation with ( 3 H)‐ or ( 14 C)methyl iodide of the sulphide anions formed on deprotection of the corresponding S‐benzyl‐homocysteine precursors with sodium in liquid ammonia. After purification by LC, the labelled peptides were obtained in radiochemical yields in the range of 9 to 24 % with a radiochemical purity higher than 97%. The specific radioactivities of the 3 H‐ and 14 C‐labelled products, corresponding to the labelled methyl iodides used, were 80 mCi/μmol and 60 μCi/‐μmol, respectively.