Influence of Polymer Structure on Protein Partitioning in Two‐Phase Aqueous Systems

Abstract

Copolymers of acrylamide and styrene with two distinct structures were synthesized to study the effect of polymer structure on protein partitioning in two-phase aqueous systems. Micellar copolymerization was used to prepare a multiblock copolymer, while homogeneous copolymerization was used to prepare a random copolymer, both with the same composition and molecular weight. Phase behavior studies of the copolymers with poly(ethylene glycol) in water showed little difference in the phase boundaries. However, the partitioning of bovine serum albumin between the two aqueous phases was sensitive to the polymer structure. A molecular picture is proposed for the interactions between the protein and block copolymers. The effect of pH on the protein partition is analyzed in terms of the hydrophobic interactions, and the polymer and protein partitioning was correlated using a model based on the Flory-Huggins theory.

Aqueous Two-Phase Systems Containing Urea: Influence on Phase Separation and Stabilization of Protein Conformation by Phase Components

“…So far the knowledge of phase systems containing chaotropic compounds is very limited (5, 13). The protein surface and structure, however, is known to have a great influence on partitioning between the phases (1, 14). It is unclear how urea would affect the position of the binodial, whether the so‐called “structure breaking” effect of urea on the water or the preferential interaction with aqueous interfaces (15) would dominate in a biphasic aqueous system.…”

Influence of hydrophobe content on phase coexistence curves of aqueous two‐phase solutions of associative polyacrylamide copolymers and poly(ethylene glycol)

“…Traditional techniques used for protein purification—for example, precipitation and column chromatography—are not only expensive and difficult to scale up but also result in lower yields. Thus, in recent years there has been an ongoing interest in the development of innovative and efficient separation and purification methods in the biotechnology industry 1–5…”

“…Aqueous two‐phase systems (ATP), in which two water‐rich phases coexist in equilibrium, have gained significant interest as a method of protein purification 1–7. This novel separation methodology exploits the fact that many aqueous polymer–polymer systems, under appropriate solution conditions, can spontaneously separate into two water‐based, yet immiscible, phases.…”

Aqueous two-phase systems containing urea: Influence of protein structure on protein partitioning

“…So far the knowledge of phase systems containing chaotropic compounds is very limited (Forciniti, 1994;Lotwin and De Bernadez Clark, 1999;Spears and Forciniti, 1995;Zaslavski, 1995). The protein surface and structure, however, is known to have a great influence on partitioning between the phases (Albertsson, 1986;Hamad et al, 1996). In a preceding article we reported the influence of urea on the liquid-liquid equilibrium and determined the quaternary-phase diagrams for PEG/Na 2 SO 4 / urea/water as well as PEG/Dextran/urea/water systems (Rämsch et al, 1999).…”