Accelerated peptide bond formation at air-water interfaces.

Area of Science:

• Biochemistry
• Astrobiology
• Physical Chemistry

Background:

• Peptides and proteins are fundamental to life, built from amino acids linked by peptide bonds.
• The prebiotic mechanisms of peptide bond formation are not well understood.
• Understanding early peptide synthesis is crucial for origin of life research.

Purpose of the Study:

• To investigate the mechanisms and kinetics of peptide bond formation at air-water interfaces.
• To elucidate the role of interfaces in prebiotic chemistry.
• To model peptide bond formation using diglycine as a model system.

Main Methods:

• Utilized advanced Born-Oppenheimer molecular dynamics (BOMD) simulations.
• Investigated peptide bond formation at air-water interfaces.
• Calculated free-energy barriers for interfacial and gas-phase reactions.

Main Results:

• Discovered a novel isomerization-then-OH- elimination pathway for peptide bond formation.
• Identified that diglycine isomerizes to its acidic form at the interface, releasing OH-.
• Demonstrated significantly lower free-energy barriers (>25 kcal/mol) at the interface, especially with an electric field.

Conclusions:

• The air-water interface facilitates rapid peptide bond formation via a unique mechanism.
• This pathway is potentially applicable to larger peptides, like tetraglycine.
• Findings provide insights into the origin of life and potential synthetic peptide strategies.