RESUMO
The complex molecular formats of recent therapeutic antibodies, including bispecific antibodies, antibody fragments, and other fusion proteins, makes the task of purifying the desired molecules in a limited number of purification steps more and more challenging. Manufacturing these complicated biologics can be substantially improved in the affinity capture stage if the simple bind-and-elute mode is accompanied by targeted removal of the impurities, such as mis-paired antibodies and oligomers or aggregates. Here, we report a method, based on the binding valency to Protein L resin, of separating proteins during the elution step by simply controlling the conductivity at low pH. We show that the method efficiently separated targeted antibodies from mis-paired and aggregated species. Notably, the number of Protein L binding sites can be built into the molecule by design to facilitate the purification. This method may be useful for purifying various antibody formats at laboratory and manufacturing scales.