'Reverse chemical evolution': a new method to search for thermally stable biopolymers

Area of Science:

• Origin of life studies
• Biochemistry
• Geochemistry

Background:

• Early Earth's primitive sea may have had high temperature and pressure, similar to hydrothermal vents.
• Thermal stability of biomolecules is crucial for life's origin in such environments.
• Existing biopolymers degrade rapidly at temperatures above 200°C.

Purpose of the Study:

• To investigate a novel approach, reverse chemical evolution, for identifying thermally stable biopolymers.
• To explore the potential for stable peptides and RNAs to form under simulated ancient sea conditions.

Main Methods:

• Hydrolysis of bovine ribonuclease A at 205°C and 25 MPa.
• Analysis of resulting peptide and RNA fragments for thermal stability.
• Sequence analysis of prominent stable molecules.

Main Results:

• Three stable molecules (859, 1030, and 695 Da) were identified after hydrolysis.
• These molecules exhibited thermal stability hundreds of times greater than polyglycine.
• Sequence analysis revealed heptapeptides and homologues, rich in hydrophobic amino acids.

Conclusions:

• Reverse chemical evolution can yield exceptionally thermally stable peptides.
• These findings support the possibility of life originating in high-temperature, high-pressure environments.
• The identified peptides may represent key molecules from early life forms.