Preparative peptide purification by cation-exchange and reversed-phase perfusion chromatography

Cation exchange was compared to reversed-phase chromatography for the preparative purification of a 28-residue peptide (vasoactive intestinal polypeptide) on the 100-mg scale. Optimized high-speed, high-resolution methods were developed for both chromatographic modes on POROS Perfusion Chromatography flow-through particle chromatography columns. While both methods appeared to provide similar purity, the cation exchange column had approximately ten times the loading capacity per unit column volume as the reversed-phase column. Five-minute methods for desalting the cation exchange-purified peptide and analysis of fractions were developed using small reversed-phase columns. The cation-exchange method was scaled up to process 95 mg of crude peptide in a 12-min run.