Recombinant E.coli malate dehydrogenase (eMDH) was expressed as inclusion bodies (IBs)

and the eMDH IBs was used as a real oligomeric protein to study protein refolding from IBs assisted by two major osmolytes

betaine and trehalose.It was observed that the specific activity of eMDH was enhanced by increasing betaine concentration

while there was an optimal trehalose concentration at which the protein was favorably renatured.Furthermore

the renaturation could be improved even at high guanidinium chloride concentrations (up to 0.4 mol·L-1) in the presence of betaine or trehalose.It was shown by binding of 1-anilino-8-napthalene sulfonic acid (ANS) to eMDH as a function of osmolyte concentration at different guanidinium chloride concentrations that the hydrophobic residue exposure on eMDH surface was reduced in the presence of osmolyte.Circular dichroism (CD) spectra indicated that osmolyte could promote the formation of α-helical in eMDH.