Three novel high performance affinity chromatographic media for the separation of antithrombin III from human plasma

IgG purification using affinity filtration with sulfamethazine-affinity carriers

Immunoglobulin G (IgG) antibodies are used extensively for analytical, diagnostic, and therapeutic applications. However, there are some disadvantages to purify IgG antibodies by protein A and G affinity chromatography. Therefore, it is necessary to find an effective alternative and nonchromatographic method to purify IgG. Dextran microparticles were activated and coupled with sulfamethazine to form sulfamethazine-affinity carriers. Then the carriers were used to purify IgG by affinity filtration. Quantitative and qualitative determination proved that sulfamethazine would successfully bond to the surface of dextran microparticles with a density of 85.5 μmol/g (wet). Affinity carriers were proved to withstand high shear force and reveal rare sulfamethazine leakage under filtration conditions between pH 3 to 11. The maximum IgG-binding capacity of affinity carriers was 8.03 mg IgG/g (wet). The affinity filtration process obtained a recovery yield above 80% and purity above 90%. Thus, this work involved in both the advantages of membrane filtration and affinity purification. The results, for the first time, proved that it is possible to use the small ligand sulfamethazine for affinity filtration of IgG. It is an attractive alternative to conventional protein A or G affinity chromatography.

Specific DNA G-quadruplexes bind to ethanolamines

A significant number of G-quadruplex-forming sequences have been revealed in human genome by bioinformatic searches, implying that G-quadruplexes may be involved in important biological processes and may be new chemotherapeutic targets. Therefore, it is important to discover the potential interactions of G-quadruplexes with other molecules or groups. Here we describe a class of G-quadruplexes, which can bind to ethanolamine groups that widely exist in biomolecules and drug molecules. The specific interaction of these G-quadruplexes with ethanolamine groups was identified by high performance affinity chromatography (HPAC) using immobilized ethanolamine and diethanolamine as stationary phase reagents. The circular dichroism (CD) spectra and native polyacrylamide gel electrophoresis (PAGE) show that these ethanolamine binding quadruplexes adopt an intramolecularly parallel structure. The relationship of ethanolamine binding and G-quadruplexe structure provides new clues for the G-quadruplex-related studies as well as for the molecular designs of therapeutic reagents.

Methacrylate-based chromatographic media

This review summarizes the preparation and application of chromatographic separation media based on methacrylate monomers with a major focus on highly crosslinked macroporous beads prepared from 2-hydroxyethyl methacrylate and glycidyl methacrylate, respectively. The effects of process variables such as composition of the polymerization mixture that includes monomers, porogenic solvents, and free radical initiator, suspension stabilizer, reaction temperature, and stirring are detailed for both classical and templated suspension polymerization. In addition, specific features of the preparation of monodisperse beads are also discussed. The performance of methacrylate-based separation media is demonstrated on numerous separations in a variety of chromatographic modes.

QCM–FIA with PGMA coating for dynamic interaction study of heparin and antithrombin III

In this work, we describe a method of constructing a film of linear poly(glycidyl methacrylate) (PGMA) polymer onto the surface of quartz crystal microbalance (QCM) electrode as a coating material that allows easy coupling of heparin molecules onto the electrode and facilitates the determination of the interaction between heparin and antithrombin III (AT III). The PGMA film was characterized with atomic force microscopy (AFM) and infra-red spectroscopy. The coupling of heparin was accomplished in one step solution reaction. A home-made quartz crystal microbalance-flow injection analysis (QCM-FIA) system with data analysis software developed in our laboratory was used to determine the interaction. The interactions between immobilized heparin and AT III were studied with various concentrations under various conditions. The obtained constants are kass=(1.49+/-0.12)x10(3)mol-1ls-1, kdiss=(3.94+/-0.63)x10(-2)s-1, KA=(3.82+/-0.33)x10(4)mol-1l.

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.