Oxidative protein refolding on size exclusion chromatography: From batch single-column to multi-column counter-current continuous processing

Recently protein refolding on size exclusion chromatography (SEC) operated in multi-column continuous simulated moving bed (SMB) configurations (hereinafter SMB-SEC) has been investigated for future industrial applications. This is due to several advantages offered by SMB configurations particularly when process parameters are thoroughly screened and optimized. A robust mathematical model is essential for high-throughput process screening and optimization. In this work, a previously investigated single-column mathematical model was modified to extend its applicability for protein oxidative refolding/aggregation predictions in SMB-SEC. The model considers a wide loading concentration range of the model protein (lysozyme) on SEC. The potential influences of high concentrations of chaotropic reagents on kinetic and thermodynamic model parameters have been discussed based on previous experimental results and their predicted local concentrations through the SMB-SEC columns and at the product stream. It was observed that aggregation occurs when local protein concentration exceeds a critical concentration. No urea recovery at the product stream indicated that the refolding reaction will continue off-column to recover the native-protein product. Therefore, it is suggested that the developed model is tested against experimental results for total soluble protein (early intermediates and native conformations) in the presence of L{small}-arginine additive and process performance indicators are defined based on this criterion.