Noncovalent interactions of amino acids with fullerene C₆₀: A dispersion-corrected DFT study

ABSTRACT

By using the general gradient approximation functional PBE with Grimme's empirical dispersion correction in conjunction with the double numerical basis set DNP, we studied the noncovalent interaction of twenty proteinogenic l-amino acids (AAs) with fullerene C₆₀. The calculations were performed both under vacuum conditions and in aqueous medium. We analyzed the calculated geometries and binding energies for AA+C₆₀ complexes, the shape of HOMO and LUMO orbitals and the corresponding gap energies. Generally, we found a poor correlation between binding energies calculated for AA+C₆₀ complexes in aqueous medium and hydrophobicity scales proposed by other other authors. Despite of C₆₀ cage can be envisioned as a typical hydrophobic surface, the AA adsorption apparently takes place according to a mechanism different from classical hydrophobic interactions, or due to a combination of several types of interactions with a limited contribution of hydrophobic mechanism.

KEYWORDS:

• amino acids
• fullerene C₆₀
• noncovalent interactions
• density functional theory
• Grimme dispersion correction

Acknowledgement

Financial support from the Universidad Nacional Autónoma de México (UNAM; grant DGAPA-IN200516) is greatly appreciated. E. G.-L. thanks the Masters Degree Program in Chemical Sciences of UNAM and CONACyT for M.Sc. fellowship.