Molecular features of interaction involving hen egg white lysozyme immobilized on graphene oxide and the effect on activity

Abstract

Nanomaterials, such as graphene oxide (GO) are being studied to decipher their suitability in biomedical applications. This study investigate the effect on structure and function of hen egg white lysozyme (HEWL) adsorbed on GO, using various biophysical techniques. In spite of there being not much change in the structure, the catalytic activity is reduced significantly. Fluorescence quenching indicates complex formation. Fluorescence lifetime measurement suggests that GO binds at or near the active site close to Trp62 and Trp108. Heat change associated with HEWL-GO interaction suggests hydrogen bond along with van der Waals and electrostatic interactions are involved in the HEWL-GO complex. Molecular docking indicates binding of GO at the active site corroborating experimental findings. Molecular dynamics simulations indicate that the blocking of the active site affects the flexibility of the surrounding residues and contribute to the reduction of the activity. Unfolding experiments indicate that HEWL is more prone to thermal instability in presence of GO. Together, the results obtained established molecular details of HEWL-GO interaction and might be useful in eventual biomedical applications of GO.