Linear polypeptides of a known repeating sequence of amino-acids. Synthesis of poly-(L-tyrosyl-L-glutamyl-L-alanylglycyl)[1-14C]glycine ethyl ester

Abstract

The o-nitrophenylsulphenyl protecting group was removed under mild conditions from N-o-nitrophenylsulphenyl-O-t-butyl-L-tyrosyl-γ-t-butyl-L-glutamyl-L-alanylglycine pentachlorophenyl ester and the product was polymerised on the partially blocked monomer [1-¹⁴C]glycine ethyl ester hydrochloride at 30, 70, and 100 mmoles/I. in order to observe the variations in polymer size and incorporation of radioactivity with concentration. The initial polymerisation gave poly-(O-t-butyl-L-tyrosyl-γ-t-butyl-L-glutamyl-L-alanylglycyl)[1-¹⁴C]glycine ethyl ester The t-butyl groups were removed to give the title compound. Polypeptides with molecular weights of ca. 1 × 10⁵ could be prepared at all concentrations, and the radioactive monomer was usually incorporated in sufficient amount for its concentration to be used to obtain another value for the molecular weight, ca. 10⁵. The agreement in molecular weight indicates the occurrence of a linear polypeptide.