| Abstract
| - Displacer lead compounds were selected from a commercially available database to identify potential selectivedisplacers for a binary protein mixture in ion exchangechromatography. Parallel batch screening experimentswere carried out with these lead compounds to study theeffect of displacer concentration on the relative amountsof the proteins displaced. Experiments were conductedwith a mixture containing ribonuclease A and α-chymo-trypsinogen A which exhibited very similar retentionbehavior under linear gradient conditions. The batchdisplacement results indicated that most of these leadcompounds were indeed selective for displacing ribonuclease A. In fact, one of these displacers exhibitedextremely high selectivity, displacing essentially all of theribonuclease A while displacing minimal α-chymotrypsinogen A at a displacer concentration of 10 mM. Theseresults were validated under column conditions, with theribonuclease A being displaced and the α-chymotrypsinogen A remaining on the column after the displacerbreakthrough. In order to examine whether this was massaction or chemically selective displacement, an affinityranking plot based on the Steric Mass Action (SMA) modelwas generated, and the results confirmed that this wasnot a mass action displacement. In order to test thehypothesis that displacer protein binding was playing arole in these separations, Surface Plasmon Resonance(SPR) was carried out. The results suggest that while thechemically selective displacer interacted with α-chymo-trypsinogen A, it had no interaction with ribonuclease A.The ability to exploit protein displacer binding in concertwith appropriate displacer resin affinities opens up newpossibilities for creating selective displacement systems.
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