Tritiated peptides. Part 2. Synthesis of two [3,5-3H2-Tyr2]-analogues of corticotrophin

Abstract

The syntheses are described of β-corticotrophin-(1–24)-tetracosapeptide and [D-Ser¹-Lys^17,18]-β-corticotrophin-(1–18)-octadecapeptide amide labelled with tritium in the tyrosine residue at position 2 to specific radio-activities of 29.0 and 17.0 Ci mmol^–1, respectively, by reductive deiodination of protected precursors. Evidence for the integrity of the final products is provided by amino-acid analysis, column chromatography, and bioassay, supported by chemical and enzymic analytical data on the protected precursors and the derived free peptides containing di-iodotyrosine.