Does macromolecular crowding compatible with enzyme stem bromelain structure and stability?

Abstract

It is essential to explore the impact of macromolecular crowding on protein in order to understand the behavior of the protein in the biological system. In this context, the consequences of macromolecular crowding on stem bromelain (BM) are explored, which is important for its industrial application. Herein, the effect of dextran (D70) and polyethylene glycol (P12 and P20) on native BM structure are investigated. The effect of crowder molecules on BM are deduced by combining the results of absorption, circular dichroism, fluorescence and activity studies. Additionally, molecular level interactions are investigated with molecular docking studies. Our results display that BM acts differently in higher and lower concentrations of crowding agents. Furthermore, crowding leads to alteration of protein structure and activity as compared to the dilute solutions. We observed that D70, is a very effective thermal stabilizing agent, while P12 is moderately stabilizing, on the other hand, P20 is destabilizing the BM structure. In the present study, the overall effect of crowders was destabilizing and deactivating on enzyme. Therefore, this study provides yet another example where soft interaction is dominating over the excluded volume effect.