Theoretical investigation of β-turn structures of serine-alanine protected dipeptide using quantum calculations

Subject Areas :

Behzad Chahkandi ^{1 *}

1 - IAU

Received: 2022-08-30 Accepted : 2022-08-30 Published : 2021-11-22

Keywords:

Abstract :

     In this research the β-turn structures of L form of serine-alanine protected dipeptide on Ramachandran map were investigated using quantum calculations at the  B3LYP/6-311+G(d,p) and M06-2X/6-311+G(d,p) levels of theory in gas phase. Amongst of 243 plossible conformers of N-For-ser-ala-NH2 protected dipeptide, 26 of the found conformers having β-turn structures. The quantum theory of atoms in molecules were carried out to characterize the nature of the intramolecular hydrogen bonding in β-turn structures. The obtained results reveal that the  conformer of type V because of including of three HBs is the most stable one between all β-turn structures. However, the most unstable ( ) β-turn conformer of type I bears two and one HBs at the B3LYP and M06-2X levels of theory, respectively.