DFT study of N–H···O hydrogen bond between model dehydropeptides and water molecule

Abstract

The strength of the hydrogen bond formed between a water molecule and two α,β-dehydroalanine derivatives including Ac-ΔAla-NMe₂ (1) and Ac-ΔAla-NHMe (2) in comparison with standard amino acid Ac-Ala-NMe₂ (3) is studied by density functional theory (with M06-2X and B3LYP functionals). Calculations were conducted for two different conformations of the peptides: extended (C₅) and bent (β) with polyproline II backbone dihedral angles. The obtained results show that both dehydro and standard peptides in bent conformation form stronger hydrogen bonds with water than in the extended ones. Moreover, due to higher polarity of the N–H group of α,β-dehydroalanine residues, the H-bond in their complexes with water are stronger than for standard alanine.

Keywords:

• dehydroamino acids
• hydrogen bond
• DFT
• M06-2X
• B3LYP

Acknowledgements

Calculations were carried out in Wrocław Center for Networking and Supercomputing, and in the Academic Computer Center CYFRONET, AGH, Kraków.

Additional information

Funding

A. Buczek is recipient of a PhD fellowship from a project funded by the European Social Fund.