Protein displacement in dye-ligand chromatography using neutral and charged polymers

Displacement chromatography was demonstrated to perform separations efficiently under mass-overloaded conditions, offering advantages such as increased product recovery and purity, superior resolving power, and concentration and purification in a single processing step. The use of water-soluble polymers for protein displacement in dye-ligand chromatography was initiated in our laboratory. The polymers for displacement were selected using differences spectroscopy to monitor their interactions with a dye-ligand in solution. Non-charged polymers such as poly(N-vinyl pyrrolidone) and poly(N-vinyl caprolactam) efficiently displaced lactate dehydrogenase from porcine muscle from a Blue Sepahrose column. The latter polymer, being thermosensitive, could be easily removed from the eluate and recovered by precipitation at 45 degrees C and low-speed centrifugation. The positively charged polymer poly(ethylene imine) proved to be an even more efficient displacer. The dye-ligand column could be regenerated after application of displacer either by washing with a solution of the soluble ligand Cibacron Blue (in the case of non-charged polymers) or by washing with highly alkaline solutions containing polyanions (in the case of poly(ethylene imine)) The latter formed a soluble complex with poly(ethylene imine) and stripped the column from the polymer.