Adsorption of Villin Headpiece onto Graphene, Carbon Nanotube, and C60: Effect of Contacting Surface Curvatures on Binding Affinity

The adsorption of protein villin headpiece (HP35) onto a graphene has been investigated using large scale molecular dynamics simulations, and the results are compared with similar adsorptions onto a single-wall carbon nanotube and a fullerene, C60. It is found that HP35 loses most of its native secondary and tertiary structures after the adsorption onto graphene. The pi-pi stacking interactions between the graphene and HP35's aromatic residues play a key role in this adsorption. The graphene's softness also helps the binding by adapting its own shape to fit better with aromatic residues in forming stronger pi-pi stacking interactions. Interestingly, the mechanism of HP35 adsorption onto the other two graphitic nanomaterials is found to be somewhat different, in which the pi-pi stacking interactions play a lesser role than the dispersion interactions between the nanomaterial and HP35's aliphatic side chains. These findings indicate that in addition to the chemical composition, the shape of the nanoparticle is also an important factor in determining its interaction with proteins: the contacting surface curvature can lead to different adsorption mechanisms.