Complex building blocks of life can form on space dust — offering new clues to the origins of life
Complex precursors to biological molecules can form spontaneously in interstellar space, according to a laboratory experiment that opens new avenues for the origin of life in the universe.
In the presence of ionizing radiation, amino acids – the simplest units of proteins – couple to form peptide bonds, the first step in the synthesis of more complex biological molecules such as enzymes and cellular proteins, according to a new study.
The cocktail of life
Early life evolved from a complex cocktail of prebiotic molecules, including amino acids, basic sugars and RNA. But how these simple starter compounds formed remains a mystery. One hypothesis suggests that some of these molecules may have come from outer space and then been transported to the early Earth by meteorite impacts, said Alfred Hopkinsonlead author of the study and a postdoctoral researcher at the Department of Physics and Astronomy at the University of Aarhus in Denmark.
Glycine, the simplest amino acid, is one example that has been detected in many samples of comets and meteorites over the past 50 years, including dust samples. taken from the asteroid Bennu during NASA’s recent OSIRIS-REx mission. More complex dipeptide units, which form when two amino acids bond to release water, have not yet been identified in these extraterrestrial bodies, but the intensely ionizing conditions of interstellar space give rise to unusual chemistry and could theoretically favor the formation of these larger molecules.
“If amino acids could join together in space and reach a higher level of complexity [dipeptides]”It’s a very exciting theory, and we wanted to see what is the limit of complexity that these molecules could form in space?”
Remaking the universe in a laboratory
The team, led by an astrophysicist from Aarhus University Sergio Ioppolotherefore sought to reproduce the conditions of space as faithfully as possible. Using the Atomki HUN-REN cyclotron in Hungary, they bombarded glycine-coated ice crystals with high-energy protons at 20 kelvins (minus 423.67 degrees Fahrenheit or minus 253.15 degrees Celsius) and 10 degrees Celsius.-9 millibar, in order to simulate space conditions as closely as possible. Then, using infrared spectroscopy and mass spectrometry – methods for identifying the types of bonds present and the molecular mass of the products, respectively – the researchers analyzed the products as they formed.
But most importantly, they used a series of deuterium labels – heavier hydrogen atoms that produce a different signal during spectroscopic analysis – to track exactly how the glycine molecules interacted.
Their marked experiment quickly confirmed their initial hypothesis: glycine molecules reacted together in the presence of radiation to form a dipeptide called glycylglycine, proving that more complex compounds containing peptide bonds could form spontaneously in space.
More chemical surprises
But dipeptides were not the only complex organic molecule generated under these conditions. A surprisingly complex signal has been tentatively identified as N-formylglycinamide, a subunit of one of the enzymes involved in the production of the building blocks of DNA and, therefore, another key player in the origin of life. chemistry.
“If you produce such a huge range of different types of organic molecules, it could impact the origin of life in ways we hadn’t thought about,” Hopkinson said. “It’s interesting to talk to other researchers – say: The world of RNA people – and see how it might change their image of the early Earth.
However, in the future, the team is studying whether this same process occurs for other protein-forming amino acids in the interstellar medium, which would potentially open up the possibility of forming more diverse and complex peptides with contrasting chemical properties.
Hopkinson, AT, Wilson, AM, Pitfield, J., Muiña, AT, Rácz, R., Mifsud, DV, Herczku, P., Lakatos, G., Sulik, B., Juhász, Z., Biri, S., McCullough, RW, Mason, NJ, Scavenius, C., Hornekær, L. and Ioppolo, S. (2026). An energetic, non-aqueous interstellar pathway to peptide formation. Natural astronomy. https://doi.org/10.1038/s41550-025-02765-7
