Regardless of the peptide production method (peptide synthesis or isolation from expression in host cells), all crude peptides need to be purified and the purity requirements for therapeutic peptides are particularly stringent. Reverse phase chromatography (RPC) is the most commonly and frequently used peptide separation technique but has its challenges. Impurities from the peptide feed are prone to cause fouling of the column and not all impurities can be resolved on the RPC column. Addition of an orthogonal step, to both protect the RPC column and to increase the resolution, could solve these issues. For example, a variety of peptide modifications that cannot be removed by RPC can be separated by ion exchange chromatography.<br/><br/>By introducing a cation exchange chromatography (CIEX) step upstream of the high-performance silica-based RPC step, the burden from impurities is significantly reduced.  In addition, the purity of the target peptide is greatly enhanced.  In this study, we present two differently produced therapeutic peptides, one solid-phase synthesized peptide and one peptide expressed in <i>Escherichia coli</i>, both purified with an upstream CIEX step before one or two RPC steps. This purification process provided the desired target peptide purity of more than 99% in both of the experimental cases.

Purification of therapeutic peptides using orthogonal methods to achieve high purity

ACS Fall 2021

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