Purification of synthetic peptides using reversible chromatographic probes based on the Fmoc molecule

A rapid, versatile, reversible procedure for purifying synthetic peptides has been developed based on the specific incorporation of 4-carboxylate Fmoc derivatives onto the terminal amino acid of peptidyl-resins. The acid stable 4-COR-Fmoc derivatives were synthesised with a variety of chemical groups thus altering the chromatographic properties of the "target" peptides and permitting their convenient purification, either by reversed-phase HPLC or ion exchange chromatography. The assembly of the peptides involved a capping step to prevent the formation of deletion forms. The 4-COR-Fmoc derivatives were incorporated either as preformed amino acid conjugates or as activated succinimidyl esters. After HF cleavage and purification the 4-COR-Fmoc probes were quantitatively removed with organic bases. The efficiency of the technique was demonstrated by the purification of small to large sized peptides, including a cyclic analogue.