Dissecting the Supramolecular Dispersion of Fullerenes by Proteins/Peptides: Amino Acid Ranking and Driving Forces for Binding to C60

Molecular dynamics simulations were used to quantitatively investigate the interactions between the twenty proteinogenic amino acids and C-60. The conserved amino acid backbone gave a constant energetic interaction similar to 5.4 kcal mol(-1), while the contribution to the binding due to the amino acid side chains was found to be up to similar to 5 kcal mol(-1) for tryptophan but lower, to a point where it was slightly destabilizing, for glutamic acid. The effects of the interplay between van der Waals, hydrophobic, and polar solvation interactions on the various aspects of the binding of the amino acids, which were grouped as aromatic, charged, polar and hydrophobic, are discussed. Although pi-pi interactions were dominant, surfactant-like and hydrophobic effects were also observed. In the molecular dynamics simulations, the interacting residues displayed a tendency to visit configurations (i.e., regions of the Ramachandran plot) that were absent when C-60 was not present. The amino acid backbone assumed a tepee-like geometrical structure to maximize interactions with the fullerene cage. Well-defined conformations of the most interactive amino acids (Trp, Arg, Met) side chains were identified upon C-60 binding.

Automated summary

The study quantitatively investigated the interactions between twenty proteinogenic amino acids and C-60 using molecular dynamics simulations. It was found that the conserved amino acid backbone and the contribution from amino acid side chains played key roles in the binding, with influences from van der Waals, hydrophobic, and polar solvation interactions. The presence of C-60 led to specific configurations and geometric structures in the interacting residues and amino acid backbone.