Effect of Curvature on the α-Helix Breaking Tendency of Carbon Based Nanomaterials

Our previous study on the interaction of alpha-helical peptide with single walled carbon nanotubes (CNTs) has revealed the structural basis for the helix breaking tendency of the CNT and associated energetics (J. Phys. Chem. B 2010, 114, 14048). In this study, a systematic attempt has been made to explore the relationship between the curvature of carbon nanomaterials (NMs) and their alpha-helix breaking tendency. The interaction of a model alpha-helical peptide, polyalanine consisting of 40 residues (PA(40)) with CNTs of different chiralities ((6,6), (10,10), (14,14), and (18,18)) and planar graphene sheet has been investigated using molecular dynamics (MD) simulation approach. The structural changes in the helical peptide which is adsorbed onto the surface of the NMs of different curvatures have been derived from the MD simulation. The role of electrostatic and van der Waals energies in the interaction process has also been obtained from the MD trajectory. Results show that the extent of helix breakage induced by the NMs is inversely proportional to their curvature; that is, the helix breaking tendency is minimum for the CNT having the highest curvature and maximum for the planar graphene sheet.