Pig liver esterase (PLE) has been widely used in many fields

such as kinetic resolutions

desymmetrizations of prochiral substrates

and synthesis of nucleosides. Recombinant expression of the γ-isoenzyme of PLE (γ-PLE) in Escherichia coli can avoid the undesirable presence of several PLE isoenzymes in commercial production and interfering influence of other hydrolases

but γ-PLE expressed in Escherichia coli is usually in the form of insoluble inclusion bodies which should be refolded in vitro to recover its biological activity. Three kinds of thiol-carrying latex particles SG-DTT with different concentrations of sulphydryl groups (6.1 μmol·g-1

25.2 μmol·g-1 and 143.4 μmol·g-1) were synthesized

and then used to assist refolding of γ-PLE in vitro. The effects of particle concentration

pH

refolding temperature and urea concentration on the refolding process were investigated. It was shown that refolding should be carried out under suitable redox environment and particles with higher concentration of sulphydryl groups were more effective. The final γ-PLE activity could achieve as high as 1885 U·L-1 when γ-PLE concentration was 1000 μg·ml-1

increased by 72% than that without the particles. All results above demonstrated that thiol-carrying latex particles could assist γ-PLE refolding by attacking disul?de bonds in misfolded protein to form correct pairing through thiol/disul?de exchange reactions and inhibiting intermolecular interactions

which presented an alternative way to facilitate refolding of proteins with disulfide bonds in vitro.