Generic chromatography‐based purification strategies accelerate the development of downstream processes for biopharmaceutical proteins produced in plants

Abstract

Plants offer a valuable alternative to cultured mammalian cells for the production of recombinant biopharmaceutical proteins. However, the target protein typically represents only a minor fraction of the total protein in the initial plant extract, which means that the development of product-specific chromatography-based purification strategies is often laborious and expensive. To address this challenge, we designed a generic downstream process that is suitable for the purification of recombinant proteins with diverse properties from plant production platforms. This was achieved by focusing on the binding behavior of tobacco host cell proteins (HCPs) to a broad set of chromatography resins under different pH and conductivity conditions. Strong cation exchanger and salt-tolerant anion exchanger resins exhibited the best resolution of tobacco HCPs among the 13 tested resins, and their selectivity was easy to manipulate through the adjustment of pH and conductivity. The advantages, such as direct capture of a target protein from leaf extract, and limitations, such as low binding capacity, of various chromatography ligands and resins are discussed. We also address the most useful applications of the chromatography ligands, namely recovery of proteins with a certain pI, in a downstream process that aims to purify diverse plant-derived biopharmaceutical proteins. Based on these results, we describe generic purification schemes that are suitable for acidic, neutral, and basic target proteins, as a first step toward the development of industrial platform processes.