Pseudo-specific bioaffinity chromatography of immunoglobulin-G

Abstract

Poly(2-hydroxyethyl methacrylate) (PHEMA) beads with an average size of 100–150 μm were obtained by suspension polymerization. l-Histidine was immobilized onto these adsorbents. Elemental analysis of l-histidine-immobilized beads for nitrogen was estimated as 62.3 mg l-histidine/g. PHEMA/ l-histidine beads were used in the separation of immunoglobulin-G (IgG) from aqueous solutions and/or human plasma in a packed bed column system. IgG adsorption capacity of the beads decreased with an increase in the flow rate. The maximum IgG adsorption was observed at pH 6.0 for Mes buffer. IgG adsorption onto the plain PHEMA was negligible. Higher adsorption values (up to 149 mg/g) were obtained in which the PHEMA/ l-histidine sorbents were used from aqueous solutions. IgG adsorption increased with decreasing temperature and the maximum adsorption was achieved at 4 °C. Higher amounts of IgG were adsorbed from human plasma (up to 196 mg/g) with a purity of 92%. Adsorption capacities of other blood proteins were obtained as 9.6 mg/g for fibrinogen and 17.3 mg/g for albumin. The total protein adsorption was determined as 224 mg/g. The pseudo-specific affinity beads allowed one-step separation of IgG from human plasma. IgG molecules could be repeatedly adsorbed and desorbed with these sorbents without noticeable loss in their IgG adsorption capacity.