Polyelectrolytes synthetic, protein precipitation

Abstract Natural and synthetic polyelectrolytes have acquired notable importance in recent years due to their increasing application in different areas. One of these is downstream process methods which include the recovery, separation, concentration and purification of target enzymes from their natural sources. Polyelectrolytes interact with proteins to form soluble or non-soluble complexes. The interaction is driven by experimental variables of media such as pH, protein isoelectrical value, polyelectrolyte pKa, ionic strength and the presence of salts. The concentration of polyelectrolytes necessary to precipitate a protein completely is of the order of 10 " - 10 % p/v. Precipitation of protein by PE is a novel technique integrating clarification, concentration and initial purification in a single step. This chapter presents some properties of aqueous solutions of natural and synthetic PE as a tool to use them in the protein downstream process. 

A wide variety of synthetic and natural PE can interact with globular proteins to form stable protein-polyelectrolyte complexes (PE-P) that result in the formation of soluble or non-soluble complexes [5, 47]. The non-soluble complex can be easily separated by centrifugation or simple decantation. Precipitation as a concentration step offers several advantages in that it is easy to scale up, uses simple equipment and can be based on a large variety of alternative precipitants. When PE-P is specifically formed with one of the proteins in the crude extract followed by a phase separation, the process could be used as a convenient strategy for the isolation and purification of the target protein [8]. 

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