DYNAMIC FED-BATCH REFOLDING BEHAVIOR OF DENATURED-REDUCED LYSOZYME AT HIGH CONCENTRATIONS

Protein refolding process by fed-batch dilution is a course of protein dilution and refolding at the same time. In this work, the dynamic fed-batch refolding behavior of denatured-reduced lysozyme at concentrations up to 7mg·ml -1 was investigated to find the influence of some important factors, including the concentrations of denaturant (guanidine hydrochloride), lysozyme and redox reagents. The fed-batch refolding was operated by 60min fed-batch dilution and 24h incubation at 37℃. In the fed-batch process, the denatured-reduced protein could rapidly reach homogeneous distribution and be kept at low concentration in the refolding buffer, so the formation of protein aggregates was greatly suppressed. Thus, significantly higher refolding yield was obtained by the fed-batch dilution than direct dilution. With the increase of final lysozyme concentration, the fed-batch refolding yield decreased somewhat. However, this decrease could be alleviated by properly increasing guanidine hydrochloride concentration in the refolding buffer. In addition, at lysozyme concentrations higher than 3mg·ml -1, increased oxidizer concentration was needed to enhance the rate of intramolecular disulfide bond formation and thus the rate of protein refolding.