Affinity Membranes and Monoliths for Protein Purification

Affinity capture represents an important step in downstream processing of proteins and it is conventionally performed through a chromatographic process. The performance of this step highly depends on the type of matrix employed. In particular, resin beads and convective materials, such as membranes and monoliths, are the commonly available supports. The present work deals with non-competitive binding of bovine serum albumin (BSA) on different chromatographic media functionalized with Cibacron Blue F3GA (CB). The aim is to set up the development of the purification process starting from the lab-scale characterization of a commercially available CB resin, regenerated cellulose membranes and polymeric monoliths, functionalized with CB to identify the best option. The performance of the three different chromatographic media is evaluated in terms of BSA binding capacity and productivity. The experimental investigation shows promising results for regenerated cellulose membranes and monoliths, whose performance are comparable with those of the packed column tested. It was demonstrated that the capacity of convective stationary phases does not depend on flow rate, in the range investigated, and that the productivity that can be achieved with membranes is 10 to 20 times higher depending on the initial BSA concentration value, and with monoliths it is approximately twice that of beads, at the same superficial velocity.

An experimental model of affinity filtration for the isolation of egg white Lysozyme using Cibacron Blue immobilized to yeast cells

An experimental model of affinity filtration process was designed using a macroligand composed by Cibacron Blue F3GA immobilized to yeast cells. Its performance was evaluated, at bench scale, through the recovery of egg white Lysozyme. The selective and reversible binding between the Cibacron ligand molecule and the enzyme is described. The separation of Lysozyme from the protein mixture included the application of stages such as affinity adsorption, concentration, diafiltration and elution. A tangential microfiltration system with an inorganic membrane was designed. The main finding was the development of the diafiltration operation, key stage in the enzyme isolation. The macroligand particle kept its integrity along the whole process and the degree of purity of the isolated Lysozyme was significant.

Preparation of dye–ligand affinity chromatographic packings based on monodisperse poly(glycidylmethacrylate-co-ethylenedimethacrylate) beads and their chromatographic properties

Monodisperse porous particles, poly(glycidylmethacrylate-co-ethylenedimethacrylate), P(GMA-EDMA) beads with diameter of 7 microm were prepared by a single-step swelling and polymerization method. The polymer particles were advantaged through immobilization of Procion Bule MX-R, which was incubated by epichlorohydrin via the epoxide groups on the particles surface. The Procion Bule MX-R-immobilized P(GMA-EDMA) beads were mechanically stable and acted as the rigid matrix for column chromatography in HPLC mode. The chromatographic properties of the dye-ligand affinity chromatographic stationary phase for biopolymers separation are discussed. This affinity column has advantages of enabling biopolymer separation, high efficiency and low backpressure. Lysozyme and BSA were fast separated within 10min using this affinity column. The column was also used for the purification of lysozyme from chicken egg white.

Dye-ligand affinity systems

Dye-ligands have been considered as one of the important alternatives to natural counterparts for specific affinity chromatography. Dye-ligands are able to bind most types of proteins, in some cases in a remarkably specific manner. They are commercially available, inexpensive, and can easily be immobilized, especially on matrices bearing hydroxyl groups. Although dyes are all synthetic in nature, they are still classified as affinity ligands because they interact with the active sites of many proteins mimicking the structure of the substrates, cofactors, or binding agents for those proteins. A number of textile dyes, known as reactive dyes, have been used for protein purification. Most of these reactive dyes consist of a chromophore (either azo dyes, anthraquinone, or phathalocyanine), linked to a reactive group (often a mono- or dichlorotriazine ring). The interaction between the dye ligand and proteins can be by complex combination of electrostatic, hydrophobic, hydrogen bonding. Selection of the supporting matrix is the first important consideration in dye-affinity systems. There are several methods for immobilization of dye molecules onto the support matrix, in which usually several intermediate steps are followed. Both the adsorption and elution steps should carefully be optimized/designed for a successful separation. Dye-affinity systems in the form of spherical sorbents or as affinity membranes have been used in protein separation.

Novel hydrophobic ligand-containing hydrogel membrane matrix: preparation and application to gamma-globulins adsorption

In this study, phenylalanine as a hydrophobic ligand was covalently attached to the co-monomer methacrylochloride. Then, poly(2-hydroxyethylmethacrylate-co-methacrylamidophenyalanine) [poly(HEMA-MAPA)] membranes were prepared by UV-initiated photopolymerization of HEMA and methacrylamidophenyalanine. The gamma-globulins adsorption onto these affinity membranes from aqueous solutions containing different amounts of gamma-globulins at different pH was investigated in a batch system. The gamma-globulins adsorption capacity of the membranes was increased as the ligand density on the membrane surface increase. The non-specific adsorption of the gamma-globulins on the pHEMA membranes was negligible. The adsorption phenomena appeared to follow a typical Langmuir isotherm. The maximum adsorption capacity (q(m)) of the poly(HEMA-MAPA4) membrane for gamma-globulins was 2.37 mg g(-1) dry membrane. The equilibrium constant (k(d)) value was found to be 1.61x10(-1) mg ml(-1). More than 87% (up to 100%) of the adsorbed gamma-globulins were desorbed in 120 min in the desorption medium containing 50% ethylene glycol in 1.0 M NaCl.