C60@Lysozyme: Direct Observation by Nuclear Magnetic Resonance of a 1:1 Fullerene Protein Adduct

Integrating carbon nanoparticles (CNPs) with proteins to form hybrid functional assemblies is an innovative research area with great promise for medical, nanotechnology, and materials science. The comprehension of CNP-protein interactions requires the still-missing identification and characterization of the 'binding pocket' for the CNPs. Here, using Lysozyme and C-60 as model systems and NMR chemical shift perturbation analysis, a protein-CNP binding pocket is identified unambiguously in solution and the effect of the binding, at the level of the single amino acid, is characterized by a variety of experimental and computational approaches. Lysozyme forms a stoichiometric 1:1 adduct with C-60 that is dispersed monomolecularly in water. Lysozyme maintains its tridimensional structure upon interaction with C-60 and only a few identified residues are perturbed. The C-60 recognition is highly specific and localized in a well-defined pocket.