Ab initio computational study of reaction mechanism of peptide bond formation on HF/6-31G(d,p) level

Peptide plays an important role in modulation of various cell functions. Therefore, formation reaction of the peptide is important for chemical reactions. One way to probe the reaction of peptide synthesis is a computational method. The purpose of this research is to determine the reaction mechanism for peptide bond formation on Ac-PV-NH₂ and Ac-VP-NH₂ synthesis from amino acid proline and valine by ab initio computational approach. The calculations were carried out by theory and basis set HF/6-31G(d,p) for four mechanisms (path 1 to 4) that proposed in this research. The results show that the highest of the rate determining step between reactant and transition state (TS) for path 1, 2, 3, and 4 are 163.06 kJ.mol^-1, 1868 kJ.mol^-1, 5685 kJ.mol^-1, and 1837 kJ.mol^-1. The calculation shows that the most preferred reaction of Ac-PV-NH₂ and Ac-VP-NH₂ synthesis from amino acid proline and valine are on the path 1 (initiated with the termination of H⁺ in proline amino acid) that produce Ac-PV-NH₂.