A General Approach for Antibody Purification Utilizing [Protein A-Catechol:Fe³⁺] Macro-Complexes

A general platform for antibody purification utilizing free nonimmobilized Protein A modified with the strong metal chelator catechol (ProA-CAT) and Fe³⁺ ions is presented. The mechanism of purification requires formation and precipitation of macro-complexes composed of [ProA-CAT:IgG:Fe³⁺]. Target IgGs are eluted directly from the precipitates (i.e. pellets) at pH 3 in high yields (71−80%) and high purity (>95%), without dissociating the [ProA-CAT:Fe³⁺] insoluble macro-complex.