Insight on the biomimetic of lysozyme interaction with functionalized iron oxide nanoparticles

Lysozyme is a globular hydrolytic enzyme whose tissue level is imperative for various clinical diagnostics. High levels of lysozyme are related to several inflammatory disorders, that breakdown cartilaginous tissues. Recently nanostructures have become widely used as modulators for enzyme activity.

This study delves into the influential role played by surface-modified iron oxide nanoparticles (IONPs) as novel lysozyme nano-inhibitors. Stern-Volmer plots results for lysozyme interaction with Cit-IONPs and Thy-IONPs reveal dynamic quenching constant (KSV) of 40.075 and 65.714 ml/mg, binding constant (Kb) of 1.539 × 103 and 4.418 × 103 ml/mg, and binding free energy (∆G°binding) of -43.563 KJ. mol^-1 and -49.821 KJ. mol^-1, respectively. Upon interaction with IONPs, the catalytic activity of lysozyme decreases due to conjugation with Thy-IONPs and Cit-IONPs compared to the free form of the enzyme. Computational approaches show that the citrate and thymoquinone molecules have binding affinities with lysozyme active residues of about -4.3 and -4.7 kcal/mol, respectively.

Both formulations of IONPs demonstrate high affinity toward lysozyme proteins. This work shows a higher binding affinity between lysozyme and Thy-IONPs than with Cit-IONPs. These findings suggest that Thy-IONPs represent a promising class of nano-inhibitors for lysozyme, opening new avenues for treating disorders associated with lysozyme overexpression.