Investigating the Effect of Maltodextrin on the Enzyme Stability in the Molecular Crowding Conditions

Cell cytoplasm consists of several molecules that have different shape and sizes and therefore the interior of cells is a crowded environment. Most of investigations on activity and stability of enzymes have been carried out in dilute solution that differs from in vivo condition. Horseradish peroxidase (HRP) enzyme is a plant enzyme that has many applications in industrial, biotechnology and medical diagnostic. Our previous investigation indicated that thermal stability of HRP decreases in the crowded condition. Here, stability of HRP has been evaluated in the crowded conditions in absence and presence of maltodextrin as a stabilizing additive. The research aims to find out whether solvent engineering that is a strategy for coping with stress conditions in the cell influences in the protein stability on the crowded condition. The results indicated that thermal stability of the enzyme decreases in polyethylene glycol (PEG) 10% and maltodextrin 20% leads to improve its thermal stability not only in diluted solution but also in the crowded solution. The results also implied that at the denaturing temperature below 60 ° C maltodextrin is more effective than the higher temperatures. In addition to the thermal stability, the additive enhances chemical stability of the enzyme in the absence and presence of PEG 10% remarkably. Unlike chemical and thermal stability, maltodextrin has little effect on stability of the enzyme in the organic solvents. In conclusion, the results showed that molecular crowding significantly decreases the enzyme stability under the environmental stress conditions, and maltodextrin, as a stabilizing agent, increases its stability in the unfavorable conditions. Consequently, we can probably assume that natural strategy for stabilization of cell proteins is a helpful strategy for stabilization of proteins in the crowded conditions inside the cell.