Conformational Structures and Vibrational Spectroscopic Investigation of Isolated Dityrosine and Tryptophan-Tyrosine Dipeptides: A Theoretical Study

Publication date: Available online 3 April 2018 Source:Computational and Theoretical Chemistry Author(s): Maricris L. Mayes, Lisa Perreault Aromatic peptides can form dipeptides which could then self-assemble into nanostructures. However, there is still a lack of fundamental understanding between structures and properties of these materials. We use dispersion-corrected density functional theory and second-order Møller Plesset perturbation theory to study a few lowest energy structures and the corresponding vibrational spectra of linear and cyclic dityrosine (YY) and tryptophan-tyrosine (WY), the building blocks of four different aromatic dipeptide nanotubes. The variation in relative energies predicted by the different methods indicates that a judicious choice of levels of theory is critical for these systems. We find common geometrical features for the systems of interest. For linear YY and WY, the most stable conformers are characterized by intermolecular hydrogen bonding of the carboxylic hydroxyl group with the carbonyl of the amide. For cyclic YY and WY, the most stable conformers assume a slightly puckered boat structure for the diketopiperazine ring with the aromatic side chains in pseudoaxial and pseudoequatorial positions. All the systems considered in this study possess at least two aromatic groups suggesting that π-π stacking interaction, in addition to hydrogen bonding, is an essential factor behind aggregation of self-assembled structures from peptide-base...
Source: Computational and Theoretical Chemistry - Category: Chemistry Source Type: research