PROTECTED AMINO-ACIDS AS NOVEL LOW-MOLECULAR-WEIGHT DISPLACERS IN CATION-EXCHANGE DISPLACEMENT CHROMATOGRAPHY

Although the ability to carry out simultaneous concentration and purif ication in a single displacement step has significant advantages for d ownstream processing of pharmaceuticals, a major impediment to the imp lementation of displacement chromatography has been the lack of suitab le displacer compounds. An important recent advance in the state of th e art of displacement chromatography has been the discovery that low-m olecular-weight dendritic polymers can be successfully employed as dis placers for protein purification in ion-exchange systems. In this arti cle, protected amino acid esters (based on arginine and lysine) are sh own to be useful displacers for protein purification in cation-exchang e systems. A dynamic affinity plot is employed to evaluate the affinit y of these low-molecular-weight compounds under displacement condition s. In contrast to large polyelectrolyte displacers, the efficacy of th ese low-molecular-weight displacers was shown to be dependent on both the initial carrier salt concentration and the displacer concentration . In addition to the fundamental interest generated by low-molecular-w eight displacers, it is likely that these displacers will have signifi cant operational advantages as compared with large polyelectrolyte dis placers. (C) 1995 John Wiley & Sons, Inc.