Partition features and renaturation enhancement of chymosin in aqueous two-phase systems

Aqueous two-phase systems of polyethylene glycol (molecular mass 1450, 3350 and 6000)–phosphate and polyethylen-polypropilen oxide (molecular mass 8400)–maltodextrin systems were used in order to study the partition features of recombinant chymosin from inclusion bodies. These systems in the presence of 8 M urea were used for the solubilization of inclusion bodies containing recombinant chymosin and for the oxidative renaturation of this protein. Recombinant chymosin showed to be partitioned in favour of the top phase in all studied systems with a partition coefficient between 4 and 6. The recovery of the chymosin biological activity was 32% in the polyethylen-polypropilen oxide, while in the polyethylene glycol–phosphate the recovery was 50–59%. The results indicate that the liquid–liquid extraction would be an adequate tool able to isolate and concentrate chymosin from inclusion bodies with a yield of biological activity higher than that obtained from the standard method (43%).