Stability and enzyme activity of lysozyme in the presence of Fe3O4 nanoparticles

The goal of this work was investigation the effect of adsorption the Fe3O4 as magnetic nanoparticle on lysozyme activity and thermal stability. The turbidimetric assay (activity) of lysozyme was followed by the decreased optical density of a turbid cell suspension (about 0.3 mg/cm3 Micrococcus lysodeikticus) photometrically at 450 nm. In this study, the effect of nano-Fe3O4 on lysozyme activity was investigated by UV–Vis spectrophotometry at pH = 7.25 at 35 °C using sodium phosphate buffer. Measurements were carried out using 6 × 10−8 M (0.1 mg/cm3) concentration of lysozyme and a range of nano-Fe3O4 concentrations between 0 and 0.06 mg/cm3. It was found that by increasing nano-Fe3O4, the rate of M. lysodeikticus lyses (lysozyme activity) increases. The thermal stability of lysozyme was investigated in the presence of nano-Fe3O4 over the temperature range of 293–363 K in sodium phosphate buffer and pH = 7.25. Results indicated that by increasing nano-Fe3O4, the thermal stability of lysozyme increases.