Sanibel Symposium

Self-assembled peptide nanotubes have many potential applications in the fields of energy, nanobiotechnology, and nanomedicine. Peptides serve as excellent building blocks due to their high availability and versatility. Tyrosine-based dipeptides self-assemble to form higher order structures. In this presentation, we describe our work on dimers of linear dityrosine (YY) and tryptophan-tyrosine (WY) to gain insights into the nature of intermolecular interactions contributing to the early stages of the self-assembly of aromatic dipeptides. We use quantumchemical methods with dispersion corrections and universal solvation model based on density in combination with energy decomposition and natural orbital bond (NBO) analyses. We show that hydrogen bonding is a major stabilizing force. The lowest energy structure for the linear YY dimer is characterized by O_carboxyl···H(O)_tyr. while the lowest energy dimer of linear WY is dominated by Ocarboxyl···H(N)_trp and _πtyr···_πtyr. The role of solvent is important as it impacts the strength and nature of interactions. The lowest energy for linear WY dimer in acetone is stabilized by Ocarboxyl···H(O)_tyr, _πtrp···H(C), and _πtrp···H(N). The ∆G of dimerization and stabilization energies of solvated dipeptides reveal that the dipeptide systems are more stable in the solvent phase than in gas-phase. NBO confirms increased magnitudes for donor-acceptor interaction for the solvated dipeptides.