Exploring change in the structural integrity of lysozyme in presence of ZnONP: A thermodynamic-based approach

Abstract

Proteins maintain a dynamic 3D structure essential for homeostasis, governed largely by noncovalent interactions sensitive to physicochemical changes. Metal nanoparticles, used for biological applications for their unique properties, in a biological milieu adsorb proteins to form protein-corona, disrupting the intramolecular interactions governing the protein's native structure and functions. Understanding these changes is crucial for sustainable nanoparticlebased biological applications. In this line, lysozyme-zinc oxide nanoparticle (ZnONP) interactions at pH 7.4 and 9, and their effect on the protein conformations are explored.Lysozyme with different molecular interacting interfaces, at two different pH, interacted differently with the same ZnONP interface. The native conformation of lysozyme, characterized by a melting temperature of 345.2 K, upon entropically driven interaction with the NP, adapted a partially unfolded conformation with a melting temperature of 343.9 K and reduced protein-mediated antibacterial activity. Whereas partially unfolded lysozyme at pH 9 adapted a native-like rigid conformation and the activity with a melting temperature of 345 K, which is comparable to the native protein, upon enthalpically driven interaction with the NP surface.