Thermal Inactivation and Aggregation of Lysozyme in the Presence of Nano- TiO2 and Nano-SiO2 in Neutral pH

Protein aggregation is a problem in biotechnology. High temperature is one of the most important reasons to enhance enzyme inactivation and aggregation in industrial systems. This work focuses on the effect of TiO2 and SiO2 nanoparticles on refolding and reactivation of lysozyme. In the presence of TiO2 and SiO2 nanoparticles, after enzyme heat treatment at 98C for 30 min, not only aggregates were observed, but the amount of those increased. Hence the residual activity of lysozyme (without additives) and even in the presence of TiO2 and SiO2 nanoparticles after heat treatment was very low (<5%). Tm of the aggregated lysozyme after this heat treatment was decreased with increasing concentrations of TiO2 and SiO2 nanoparticles from 0 to 0.02 mg/ml in neutral pH, Whether the Tm of natural enzyme was above 373 (K) or 100C. these nanoparticles help enzyme denaturation and misfolding in heating. Article history: Received 2/7/2013 Accepted 13/10/2013 Published online 1/12/2013