New research on chemical reactions in space ‘could impact the origin of life in ways we never thought of’

Complex precursors of biomolecules can form spontaneously in interstellar space, according to a laboratory experiment that opens a new path to the origins of life in the universe.

In the presence of ionizing radiation, amino acids, the simplest units of proteins, combine to form peptide bonds, according to new research. This is the first step in the synthesis of more complex biomolecules such as enzymes and cellular proteins.

The findings, published in the journal Nature Astronomy on January 20, offer new possibilities about the origins of life on Earth and could help scientists target the search for extraterrestrial life, the study authors said.

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cocktail of life

Early life evolved from a complex cocktail of prebiotic molecules, including amino acids, basic sugars, and RNA. However, how these simple starter compounds were initially formed remains a mystery. “One hypothesis suggests that some of these molecules may have originated in space and were later delivered to the early Earth by meteorite impacts,” said Alfred Hopkinson, lead author of the study and a postdoctoral researcher at the Department of Physics and Astronomy at Aarhus University in Denmark.

Glycine, the simplest amino acid, is one example that has been detected in numerous comet and meteorite samples over the past 50 years, including dust samples taken from the asteroid Bennu during NASA’s recent OSIRIS-REx mission. More complex dipeptide units, formed when two amino acids combine by releasing water, have not yet been seen in these extraterrestrial bodies, but the intense ionization conditions of interstellar space could trigger unusual chemical reactions that could theoretically promote the formation of these larger molecules.

“What if amino acids could combine in space and reach the next level of complexity?” [dipeptides]”When it gets delivered to the planet’s surface, it creates a more positive starting point for forming life. This is a very exciting theory, and we wanted to know what the limits of complexity are that these molecules can form in space,” Hopkinson told Live Science.

Remaking the universe in the laboratory

So a team led by astrophysicist Sergio Iopolo from Aarhus University aimed to recreate conditions in outer space as faithfully as possible. Using the Hunlen Atomki cyclotron facility in Hungary, they irradiated the glycine-coated ice crystals with high-energy protons at 20 Kelvin (minus 423.67 degrees Fahrenheit, or minus 253.15 degrees Celsius) and 10-9 millibars to simulate conditions in the universe as accurately as possible. The researchers then analyzed the products as they formed using infrared spectroscopy and mass spectrometry, methods that determine the types of bonds present and the molecular weight of the products, respectively.

But importantly, they used a series of deuterium labels (heavier atoms of hydrogen that produce different signals during spectroscopic analysis) to track exactly how the glycine molecules interacted.

Their labeled experiments quickly confirmed their initial hypothesis. In short, glycine molecules react with each other in the presence of radiation to form a dipeptide called glycylglycine, proving that more complex compounds containing peptide bonds can spontaneously form in space.

More chemical surprises

However, dipeptides were not the only complex organic molecules produced under these conditions. One surprisingly complex signal has been tentatively identified as N-formylglycinamide, a subunit of one of the enzymes involved in the production of DNA building blocks, thus playing another important role in the chemistry of the origin of life.

“Being able to create such a wide variety of organic molecules could impact the origin of life in ways we never imagined,” Hopkinson said. “It will be interesting to talk to other researchers, for example people in the RNA world, and see how it changes their image of early Earth.”

But the team will now investigate whether this same process occurs with other protein-forming amino acids in the interstellar medium, which could open up the possibility of forming more diverse and complex peptides with contrasting chemistries.