Influence of Water Activity and Molecular Mobility on Peroxidase Activity in Solution

摘要

The effectiveness of a solute in the inhibition of enzymatic activity in concentrated solutions depends on the thermodynamical properties of the solution, as described by a_w, and on the mobility of the system, as described by η~(-v) and T'g. In viscous binary solutions, the mobility of the system as described by viscosity and T'g is the most important factor in the inhibition of enzymatic activity, while water activity has different effects depending on the chemical nature of the solute. In complex ternary systems characterized by the same viscosity value, a_w lowering does not always result in a decrease of enzymatic activity, especially when it is achieved by the addition of a ligand which acts as a plasticizer by depleting the T'g of the system. Chemical and physical stability factors were proven to play a key role on the regulation of enzymatic activity in solutions; thus, a deeper understanding of their importance is needed to better investigate the enzyme activity and stability of biological systems. Moreover, investigations on the effect of co-solutes, which could be used by the industry to achieve enzymatic stability, could find practical application in the shelf-life testing of foods and pharmaceutical formulation.