PURIFICATION OF TRYPTOPHAN CONTAINING SYNTHETIC PEPTIDES BY SELECTIVEBINDING OF THE ALPHA-AMINO GROUP TO IMMOBILIZED METAL-IONS

Immobilised metal ion affinity chromatography (IMAC) based on selectiv e binding via the alpha-amino group to Cu2+ and Ni2+ ions has been use d to purify tryptophan containing synthetic peptides. A free alpha-ami no group, serving as an affinity handle, is present only in the target peptide when the peptides are synthesised by the solid-phase method a nd remaining amino groups after each coupling step are blocked by acet ylation. A free alpha-amino group is necessary to retain the peptide o n the column. The tryptophan residue may contribute to the binding onl y if the peptide is simultaneously anchored via the alpha-amino group.