Thioesters provide a plausible prebiotic path to proto-peptides.

Area of Science:

• Astrobiology
• Organic Chemistry
• Biochemistry

Background:

• Abiotic peptide formation is crucial for understanding the origins of life.
• Existing prebiotic peptide synthesis methods face challenges like high activation energies, unfavorable thermodynamics, and reliance on unstable high-energy molecules.
• Thioester intermediates have been explored but require constant replenishment of energy-rich molecules.

Purpose of the Study:

• To investigate a plausible prebiotic pathway for proto-peptide formation.
• To identify reactions that bypass the limitations of current abiotic peptide synthesis methods.
• To explore the formation of molecules containing both peptide and thioester bonds.

Main Methods:

• Investigated reactions between mercaptoacids and amino acids.
• Utilized simple drying and heating conditions.
• Examined reactions across a wide range of pH and temperature.

Main Results:

• Successfully synthesized thiodepsipeptides, which contain both peptide and thioester bonds.
• Demonstrated that thiodepsipeptide formation occurs readily via a one-pot reaction.
• Achieved synthesis under diverse pH and temperature conditions without high-energy molecules.

Conclusions:

• The developed method provides a robust and prebiotically plausible pathway for proto-peptide formation.
• Thiodepsipeptides and thiol-terminated peptides likely formed readily on early Earth.
• These molecules could have played a significant role in early chemical evolution.