Peptide synthesis. Part 5. Solid-phase synthesis of [15-leucine]little gastrin

Abstract

A procedure is described for the solid-phase synthesis of gastrin peptides exemplified by [15-leucine]little gastrin. The method makes use of a polar polyamide resin support and stepwise addition of fluorenylmethoxycarbonylamino-acid derivatives. Treatment with acidic reagents is minimised, obviating the need for side-chain protection of tryptophan and eliminating acid-catalysed side reactions at the multiple glutamyl residues. Formation of the terminal pyroglutamyl residue was achieved through a glutaminyl intermediate.