Investigation of the CuO nanoparticles effect on activity and structure of Lepidium draba peroxidase enzyme

Entrance nanoparticles into the environment provides possibility of their entry into living organisms body. Their entry into the body can affect biological macromolecules and affect their life. Here, to investigate effect of copper oxide nanoparticle (nCuO) on recombinant Lepidium draba peroxidase, changes in enzyme activity and structure were analyzed in the presence of nCuO. Enzyme activity was measured in the presence of different concentrations of nCuO and repeated three times. Results were statistically analyzed using SPSS software at a significance level of 5%. Intrinsic fluorescence studies in the presence of nanoparticles were utilized to investigate structural changes of the enzyme. These studies were done at different temperatures to determine thermodynamic parameters such as the type of forces involved in the nanoparticle-enzyme interaction. Enzyme activity in the presence of nCuO significantly increased at the level of 5%. The most enzyme activity were attributed to the concentration ranges of 80-180 nM nanoparticles, which it increased more than 46% compared to the control. Intrinsic fluorescence intensity decreased in the manner nanoparticles concentrations increased in media. Decrease intrinsic fluorescence emission indicates changes in the enzyme structure in presence of nanoparticle. Thermodynamic parameters including entropy (∆S°) and enthalpy (∆H°) related to the interaction of enzyme with nanoparticle were calculated as 0.108 and 3.81 respectively. The positive sign of these parameters indicates the important role of hydrophobic interactions in this process. On the other hand, negativity of free energy (∆G°) changes indicates that this process is exergonic and proceeds spontaneously.