A Possible Path to Prebiotic Peptides Involving Silica and Hydroxy Acid-Mediated Amide Bond Formation

Area of Science:

• Prebiotic chemistry
• Geochemistry
• Polymer science

Background:

• Understanding the origins of life requires investigating prebiotic chemical reactions.
• Mineral surfaces are hypothesized to play a crucial role in catalyzing the formation of biomolecules.

Purpose of the Study:

• To investigate the formation of alanine and glycine oligomers using lactic acid and silica nanoparticles as a model prebiotic reaction.
• To elucidate the role of silica in promoting oligomerization and the nature of the chemical bonds formed.

Main Methods:

• Aqueous mixtures of lactic acid and silica nanoparticles were dried to form films.
• Oligomerization was studied under acidic and evaporative conditions at temperatures as low as 85°C.
• Product analysis focused on the types of chemical linkages (amide, ester) present in the oligomers.

Main Results:

• Silica addition enriched alanine and glycine in the resulting polymers.
• Oligomerization proceeded via ester-mediated peptide bond formation.
• Dominant products were rich in amide bonds and deficient in ester linkages, suggesting a transition from depsipeptides to peptides.
• Silica particles prereacted with lactic acid showed similar product distributions, indicating a catalytic surface role.

Conclusions:

• Silica nanoparticles and lactic acid can catalyze the formation of alanine and glycine oligomers under mild prebiotic conditions.
• The findings suggest a catalytic role for mineral surfaces in the prebiotic synthesis of peptides.
• This study highlights the potential importance of minerals in the transition from depsipeptides to peptides in early Earth environments.