Role of amphiphilic [metal:chelator] complexes in a non-chromatographic antibody purification platform

Abstract

We have recently introduced a non-chromatographic alternative for antibody (Ab) purification, one which does not require the use of Protein A. With this approach, polyclonal human or mouse immunoglobulins (IgG's) are captured almost quantitatively by Tween-20 micelles conjugated with a [chelator:divalent metal cation] complex. Target IgG structure remains native even following extraction from the surfactant aggregate. In the present work, we explore the effect of varying both components of the [metal:chelator] pair on the yield of purified Ab. Capture efficiency is observed to correlate with the formation of sufficiently large detergent aggregates, as determined by dynamic light scattering (DLS) and polyacrylamide gel electrophoresis (PAGE). This, in turn, depends on the rigidity and aromaticity of the chelator. Detergent aggregates are stable over a wide range of pH values (pH = 3–9). Under acidic conditions (3–3.8) they lead to good IgG recovery yields (70–78%) with purity similar to that obtained with Protein A chromatography while maintaining the monomeric state of the IgG's. Finally, the influence of the environment and the presence of various water-soluble chelators (e.g. EDTA, histidine, imidazole) on process efficiency, is described.