Ion-exchange chromatography of proteins: the inside story

Abstract

Despite its inherent inefficiencies, chromatography remains the workhorse for protein purification in the pharmaceutical and biotechnology industries, with ion exchange the most widely used mode. Many aspects of a chromatographic process are still optimized empirically, but modeling is increasingly used to aid in scale-up and optimization. An overview is presented here of the needs that remain for greater insights that can inform truly predictive modeling of preparative protein separations by ion-exchange chromatography as well as guiding rational design considerations and effective heuristics. These needs can be addressed by a more complete mechanistic understanding of the relation between adsorbent and protein structure and the values of key functional parameters describing adsorption and transport. A principal focus is on specialized experimental and modeling approaches to obtain such insights; these include molecular-level models, various modes of microscopy, and chromatographic and other methods for inferring intracolumn and intraparticle behavior. The principal findings revolve around the critical role for fundamental principles of classical chemical engineering, albeit specialized for the peculiar physicochemical properties of protein solutions.