The Size Effect of Fe Nanoparticles on Hen Egg-White Lyzozyme Structure and Activity

Superparamagnetic iron oxide nanoparticles (SPIONs) with Fe3O4 molecular composition were considered for the study of protein interactions and drug delivery. Considering that SPIONs play a significant role in nanomedicine and drug delivery systems, investigating the interaction between SPIONs and a model protein and its structural and functional changes can be enlightening in scientific research. SPIONs with sizes of 20, 50, and 100 nm were selected. The UV-visible spectroscopic study showed the interaction between protein-nanoparticles. Rotational exponential imaging was used to measure the changes in the secondary structure of lysozyme in interaction with SPIONs. A significant reduction in the helical structures of the protein was observed. Protein fluorescence quenching analysis was used to understand the nature of protein-nanoparticle interaction. The interaction of SPIONs and lysozyme showed a combination of dynamic and static quenching. The activity and enzymatic properties of lysozyme attached to SPIONs were measured compared to free lysozyme. The activity decreased dramatically in all sizes of SPIONs, but the Km changed under different reaction conditions.