(326e) Membrane Chromatography: Purification of Anthrax Protective Antigen Protein Using Newly Designed Weak Anion-Exchange Membranes

Chromatography is a universal unit operation for downstream processing of biologics. Ion-exchange chromatography is the most widely used chromatographic method to capture target protein and reduce process volumes at the early stage of purification train or to remove trace impurities (i.e., virus, DNA) at the end of the downstream processing. When used as chromatography media, macroporous membranes offer low pressure drop across the column, allowing high process flow rates that translate into high productivity. Predominantly convective transport of biomolecules within the membrane bed reduces the characteristic time to access the ion exchange sites. Thus, membrane chromatography offers flow rate independent and, as we will show, higher dynamic capacities than particle chromatography, combined with high volumetric throughput.

This contribution describes the application of anion-exchange membrane chromatography for protein separations. Our newly designed weak anion-exchange membranes (AEM) were used to capture anthrax protective antigen (PA) protein from clarified PA-containing lysate (i.e., following cell lysis and centrifugation). Performance parameters, including dynamic binding capacity, purity, and recovery of PA protein were measured. SDS-PAGE analysis was used to measure the purity of PA protein. The effect of process parameters (i.e., pH, elution gradient, flow rates) on separation performance was studied. We also compare the performance of our newly designed AEMs with a commercially available AEM (Sartobind® D) and a widely used packed-bed column (HiTrapTM DEAE FF). The performance comparison of all stationary phases was carried out under identical loading and elution conditions and flow rates.