Preparation of high-capacity supports containing protein G immobilized to porous silica

This study examined the preparation of high-capacity silica supports containing immobilized protein G. A maximum content of 39 mg protein G/g silica was obtained when using 100 Å pore size silica, followed by 33 mg/g for 50 Å silica and 9.3-24 mg/g for 300-4000 Å silica. The surface coverage of protein G increased with pore size, with a maximum level of 0.037 μmol/m² being obtained for 4000 Å silica. These supports gave comparable apparent activities (i.e., 30-47% binding to rabbit immunoglobulin G [IgG]), with the highest binding capacities (71-77 mg IgG/g silica) being obtained for 50-100 Å silica.