Effect of Displacer Chemistry on Displacer Efficacy for a Sugar-Based Anion Exchange Displacer Library

A homologous series of sugar-based anion exchange displacers were synthesized and evaluated by a parallel batch displacement assay as potential displacers for protein purification in anion exchange systems. The structural variation of these homologous molecules enabled a detailed study of the relationship between structure and efficacy. The percent protein displaced was evaluated in these batch systems for two model proteins, BSA and trypsin inhibitor, as a function of displacer concentration and chemistry on a Source 15Q anion exchange resin. The results indicated that the addition of aromatic rings at the periphery of the molecule close to the charged groups increased displacer affinity. It was observed that displacers with more structural flexibility had higher efficacy up to a certain value, beyond which flexibility did not appear to affect displacer efficacy for the molecules evaluated. It was also demonstrated that long hydrophobic side chains which are not associated with the charge may lower displacer efficacy because of undesired interactions with protein molecules or the formation of micelles. Stereochemistry was also not observed to play an important role in displacer efficacy for the molecules evaluated. Finally, low molecular mass displacers with affinities higher than those previously observed were identified as part of this study.