LAUSR

Reteplase is a deleted variant of human tissue plasminogen activator with a complex structure containing nine disulfide bonds. Reteplase is expressed as inclusion bodies in Escherichia coli and needs the additional step of refolding for activation. In this study an experimental design was performed to find the optimal refolding condition for reteplase. The influence of 14 chemical additives was assessed by one factor at a time method and then Taguchi design followed by response surface methodology was employed to find compounds with most significant effects on reteplase refolding and their optimum concentration. We found that 0.13 M histidine, 1.64 M methionine, 0.33 M cysteine, and 0.34 M arginine in addition to the GSH/GSSG is the optimal condition for refolding of reteplase. We also investigated the refolding yield for inclusion bodies obtained from different E. coli strains and found that BL21 (DE3) has the best recovery yield in comparison to Rosetta-gami and Shuffle T7.