Preferred configurations of peptide-peptide interactions

Area of Science:

• Computational Chemistry
• Molecular Interactions
• Peptide Chemistry

Background:

• Understanding peptide interactions is crucial for biochemistry and drug design.
• Previous studies have explored various non-covalent interactions in model systems.

Purpose of the Study:

• To investigate the fundamental interaction preferences of peptide units.
• To elucidate the energetic landscape of N-methylacetamide dimer configurations.

Main Methods:

• High-level ab initio quantum chemical calculations were employed.
• Potential energy surfaces were analyzed to identify stable structures and transition states.

Main Results:

• The N-methylacetamide dimer exhibits a most stable NH···O hydrogen-bonded configuration, closely followed by stacked arrangements.
• Out-of-plane motion in the H-bonded dimer is stabilized by charge transfer.
• Stacked dimers are stabilized by CH···O interactions and π→π* electronic transitions.
• Repulsion between oxygen atoms prevents O(lp)→π*(CO) interactions.

Conclusions:

• Hydrogen bonding and π-stacking are key stabilizing forces in peptide dimers.
• Charge transfer plays a significant role in dictating molecular conformation.
• Electrostatic repulsion limits certain interaction pathways between amide groups.