EFFECT OF TEMPERATURE UPON THE CHROMATOGRAPHY OF PROTEINS ON POROUS-GLASS, CHEMICALLY COATED WITH N-ISOPROPYLACRYLAMIDE COPOLYMER

Wide-pore glass chemically coated with a copolymer of N-isopropylacryl amide (NIPAA) and N-hydroxyethylacrylamide (70:30) was studied as a we ak-hydrophobic sorbent for chromatography of proteins, The temperature dependence of the lysozyme chromatographic retention points to the ma ximum near a lower critical solution temperature of the copolymer (LCS T, 41 degrees C). Nevertheless, log k' vs. [(NH4)(2)SO4] plots found f or lysozyme at 25 degrees C and 45 degrees C are only slightly differe nt and indicate almost zero free energies of interaction between the p rotein and the copolymer in 0.01 M potassium phosphate solution, pH 7. 5. No temperature-modulated desorption of immunoglobulin G adsorbed to the copolymer-coated glass at 45 degrees C was observed when cooling the column to 30 degrees C. Changes in protein interactions with the p olymer grafts are apparently too weak to ensure an effective control o f protein adsorption with temperature shift near LCST. (C) 1997 Elsevi er Science B.V.