Meteorites and comets likely carried simple amino acid chains to early Earth, which led to the creation of life, scientists confirmed in a series of experiments.
It is widely thought that organisms on Earth began from a primordial stew of organic chemicals and biomolecules.
However, researchers from the University of Poitiers in France and the Friedrich Schiller University Jena and Max Planck Institute for Astronomy—both in Germany—have new evidence that extraterrestrial bodies likely introduced those ingredients to Earth.
For the experiments, the team recreated the reactions likely to take place in the interstellar medium—the material that fills the space between the stars.
They found that three chemical components—carbon, carbon monoxide and nitrogen trihydride—were essential for peptide creation, as they lead to protein polymerization in space.
A peptide is a constituent of a protein made up of a few elemental building blocks known as amino acids. These small proteins are believed to have played a part in ancient metabolic reactions that kick-started life on Earth.
Next, the researchers examined water's role in ultracold peptide formation. Water must be broken down during amino acid polymerization, which requires a lot of energy.
However, in the extreme cold of the interstellar medium, this energy barrier lowers, and short glycine chains are able to form. From glycine chains, more peptide derivatives can then appear through a chemical reaction called autocatalysis.
In other words, these super-cold conditions can reduce the confounding effect that water has on the peptide formation process.
Additionally, these peptides may contribute to the formation of protomembranes—the forebears of the membranes that surround and give structure to all living cells.
According to the study, this suggests that extraterrestrial peptides could have been key to the origin of life on Earth.
Earlier this year, researchers at the Ludwig Maximilian University of Munich suggested the flowing of molten rocks through small cracks in volcanoes might have been a perfect environment to create the building blocks of life on our planet.
Heat flows moving through cracks in volcanic rocks can result in the purification of molecules from complex mixtures of materials, which may have resulted in the creation of specific chemicals—called biopolymers—needed for life to evolve.
The full findings of the study were published in the journal Science Advances.
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