Affinity of mouse immunoglobulin G subclasses for sialic acid derivatives immobilized on dextran-coated supports

Purification of IgG and insulin on supports grafted by sialic acid developing “thiophilic-like” interactions

We developed the synthesis of new supports for the purification of insulin and IgG by affinity chromatography. The preparation of such an affinity support is performed in two steps. First, silica beads are coated with dextran polymers carrying a calculated amount of positively charged diethylaminoethyl groups in order to mask negative charges at its surface. Second, ligand is immobilized using a coupling agent. This support combines the advantages of polysaccharide phases with the excellent mechanical characteristics of silica. The existence of N-acetylneuraminic acid (sialic acid) in insulin receptor and in the antigenic determinant of IgG suggests that such an acid may develop specific interactions usable in affinity chromatography. Therefore, N-acetylneuraminic acid was used as an active ligand. The immobilization of sialic acid can be carried out by using the conventional coupling agent: the carbonyldiimidazole. The performances of these supports grafted by sialic acid were studied by high-performance liquid affinity chromatography (HPAC). The optimization of the chromatographic conditions (support characteristics and mobile phase) enabled us to observe a behavior of the type "thiophilic" of the support, which does not contain sulfone group. This new affinity support allowed a one-step separation of the IgG from mouse ascitic fluids and also allowed the insulin purification from a pancreatic extract with a good purification yields.

A novel matrix for high performance affinity chromatography and its application in the purification of antithrombin III

Viscose fiber, a regenerated cellulose, was evaluated for using as a novel matrix for high performance affinity chromatography. With a one-step activation with epichlorohydrin, heparin can be readily covalently attached to the matrix. This heparin-viscose fiber material was used for purifying antithrombin III (AT III) from human plasma. The purity of the AT III from this one-step purification is 93% as measured by SDS-PAGE and the protein recovery yield is about 90%. This column is highly specific as described by the dissociation constant of the complex of immobilized heparin and AT III, which was 2.83 x 10(-5)mol/L. And more important, this viscose fiber material demonstrated its excellent mechanical property that allows the flow rate to reach up to 900 cm/h or more.

Novel sulfamethazine ligand used for one-step purification of immunoglobulin G from human plasma

To replace conventional affinity ligand like protein A or protein G, a pseudobioaffinity ligand seems to be an alternative for the purification of immunoglobulin G (IgG). In this study, sulfamethazine (SMZ) was chosen as novel affinity ligand for investigating its affinity to human IgG. Monodisperse, non-porous, cross-linked poly (glycidyl methacrylate) (PGMA) beads were employed as the support for high-performance affinity chromatography. SMZ was immobilized on PGMA beads using bisoxirane (ethanediol diglycigyl ether) as spacer. The resultant affinity media presented minimal non-specific interaction with other proteins. Results of high-performance frontal analysis indicated that the media showed specific affinity to human IgG with a dissociation constant on the order of 10(-6) M. The SMZ affinity column proved useful for a very convenient one-step purification of IgG from human plasma. Antibody purity after a one-step purification was higher than 90%, as determined by densitometric scanning of sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified fraction under reducing condition. The results obtained indicate that SMZ is a valuable affinity ligand for purification of human IgG.

New packing materials for protein chromatography

This review describes new packing materials designed for protein chromatography, covering advances in base supports and stationary phases. Base supports are classified according to their chemical composition. Since most separation media are bead shaped, typical procedures used for their preparation are also presented. In order to provide matrices combining improved chemical stability and chromatographic performances, composite materials continue to be developed, including bonded stationary phases, pore composites and mixed carriers. The different approaches to their preparation are described and characteristics that play a major role in the chromatographic process are discussed. Recently introduced materials and some of their applications under non-denaturing conditions in the different chromatographic modes are also presented.