Improvement of structural stability and functional efficiency of chaperonin GroEL mediated by mixed salt.

GroEL is the most commonly used chaperonin protein for both in-vitro refolding of aggregating proteins as well as in-vivo solubilization of over-expressed aggregation-prone proteins of therapeutic and biotechnological applications. But sometimes the stress conditions like heat and a load of over-expressed/unfolded/misfolded proteins lead to a decrease in structural stability and functional efficiency of GroEL, which results in less recovery of substrate protein through the chaperone-mediated refolding process. So, to amend it, we have been able to optimize physicochemical conditions utilizing a cumulation of (NH4 )2 SO4 /MgCl2 in the buffer. Interestingly, we found a consequential enhancement in the aggregation prevention efficiency, refolding of the denatured substrate and ATPase activity of GroEL protein. The reason for the increased refolding and aggregation prevention efficiency might be the exposure of hydrophobic sites and enhanced ATP hydrolysis rate in presence of buffer containing (NH4 )2 SO4 /MgCl2 . The present study withal shows that GroEL under optimized conditions exhibits consequential amelioration in thermal aggregation at high temperature. Hence the optimized buffer conditions are utilizable for the folding of substrate proteins under a broad temperature range.