Obtaining active recombinant proteins from bacterial inclusion bodies using salt solutions under neutral pH conditions

Background and Aim: Eukaryotic recombinant proteins expressed in bacterial cells usually aggregate within the cells as inclusion bodies. Despite the widely-accepted theory considering inclusion bodies as inactive materials, inclusion bodies may contain large amounts of correctly-folded active recombinant proteins. Proteins trapped in inclusion bodies can be released using a high pH solution (pH ۱۱, pH ۱۲); however, they may undergo structural changes in such pH conditions that may lead to their inactivation. Shifting in pH alongside the use of metal ions can help recover protein activity.Methods: The model protein we used in this study, ۹R-Nimo.scFv, is highly active when extracted from bacterial inclusion bodies at high pH condition (pH ۱۲) but loses its activity when pH is reduced to pH ۷. We evaluated the capacity of nine salt solutions in terms of recovering protein activity in neutral pH conditions.Results: ZnSO۴ solution was the best one for this purpose. KNO۳ and MnSO۴ were also found to have a good capacity for recovering protein activity, as well.Conclusion: ZnSO۴ helps recover ۹R-Nimo.scFv activity when pH reduces from ۱۲ to ۷, the neutral pH. MnSO۴ and KNO۳ are also capable of recovering the scFv activity, but to a lesser degree.

Keywords:

Salt solutions , scFv , ZnSO۴ , KNO۳ , MnSO۴.