One-step purification and immobilization in cellulose of the GroEL apical domain fused to a carbohydrate-binding module and its use in protein refolding.

The apical domain of the chaperonin, GroEL, fused to the carbohydrate binding module type II, CBD(Cex), of Cellulomonas fimi, was expressed in Escherichia coli. The recombinant protein, soluble or from inclusion bodies, was directly purified and immobilized in microcrystalline cellulose particles or cellulose fabric membranes. Assisted refolding of rhodanese by the immobilized mini-chaperone showed a two-fold improvement as compared to a control. Using chromatographic refolding, 35% of rhodanese activity was recovered in only 5 min (mean residence time) as compared to 17% for spontaneous refolding. This mini-chaperone immobilized in cellulose could be a cost-efficient method to refold recombinant proteins expressed as inclusion bodies.