Modeling of continuous protein refolding processes

Abstract

Kinetic models of refolding and aggregation of bovine serum albumin (BSA) protein in solution and solid phases were developed. The rate constants of refolding and aggregation were obtained by fitting literature data with kinetic models of linearized refolding yield equation in batch reactor as a function of time. For solution-phase (or dilution) refolding, there was a high tendency to aggregate than to refold, reducing selectivity and yield. On the other hand, solid-phase (or on-column) refolding was shown to significantly reduce extent of aggregation. MATLAB were used to simulate dilution refolding in batch reactor, CSTR and also batch on-column refolding for loading concentration of denatured-reduced BSA of 1 mg/mL. Six different refolding schemes were chosen and modeled, which include four schemes from dilution refolding (batch single-pass, batch multiple-pass, CSTR without and with recycle) and two schemes from matrix-assisted refolding (batch single-pass and batch multiple-pass), with certain process specifications. Simulation results have shown that batch multiple-pass matrix-assisted refolding was superior in terms of cumulative yield and productivity, compared to multiple-pass batch dilution refolding. Comparison of the most optimum batch dilution and on-column refolding system to CSTR with recycle showed that the latter have higher productivity and overall cumulative yield, as long as it is operated at or above certain productivity.