Interaction between quaternary ammonium ions and dipeptides: positive anion allosteric effect

Area of Science:

• Supramolecular Chemistry
• Chemical Biology

Background:

• Dipeptides are crucial building blocks in biological systems.
• Quaternary ammonium ions are important in various chemical and biological processes.
• Understanding molecular recognition is key to designing new functional materials.

Purpose of the Study:

• To investigate the binding interactions between dipeptides with aromatic residues and quaternary ammonium ions.
• To elucidate the primary forces driving this molecular recognition event.
• To explore the potential for pi-base interactions in the binding process.

Main Methods:

• 1H-NMR spectroscopy was employed to study the binding.
• Analysis focused on the role of exchangeable protons (OH and NH) and aromatic residues.
• The interaction with the counter anion of the ammonium ion was examined.

Main Results:

• Intermolecular hydrogen bonding between dipeptide protons and the ammonium counter anion was identified as the primary binding force.
• Formation of hydrogen bonds facilitates the creation of a pi-base cavity.
• This cavity enables further interaction with the quaternary ammonium moiety.

Conclusions:

• Dipeptides with aromatic residues effectively bind quaternary ammonium ions via a dual mechanism involving hydrogen bonding and pi-base interactions.
• The findings provide insights into the design of novel host molecules for quaternary ammonium species.
• This study contributes to the understanding of supramolecular assembly involving aromatic systems.