PROTEIN COMPLEXATION WITH ACRYLIC POLYAMPHOLYTES

The interaction of dilute mixtures of proteins and ABC triblock methac rylic polyampholytes at different values of pH was investigated turbid imetrically. The onset of interaction was manifested by large changes in turbidity at certain critical pHs which lie close to the isoelectri c points of the two interacting components. Protein precipitation yiel ds in protein-polyampholyte binary mixtures followed the corresponding turbidity profiles and varied from 10% to 90%, The synthetic polyamph olytes self-aggregate around their isoelectric point. The kinetics of precipitation of one of the synthetic polyampholytes and of mixtures o f the same polymer with soybean trypsin inhibitor were studied, with t urbidity-based characteristic times (exponential fit) of 2-3 min. The kinetics of precipitation of the protein-polymer mixture are stower th an that of pure polymer because a small, but steady, long-term increas e in turbidity is observed in the former case. The pH-dependence of th e turbidity of binary mixtures of one protein and one synthetic polyam pholyte, as well as a tertiary mixture of two proteins and one polyamp holyte, were measured 30 min after the pH adjustment. The observations in these experiments along with the measured protein precipitation yi elds in the binary mixtures suggest that the protein-polyampholyte int eraction can be used to achieve separation of protein mixtures and the polyampholyte self-aggregation can be used for polymer removal and re cycling. The latter constitutes a significant advantage over the use o f homopolyelectrolytes which cannot easily be recycled. (C) 1994 John Wiley & Sons, Inc.