[astro-ph.SR] The origin of the molecular building blocks of life is a central question in science. A few α-amino acids such as glycine, the simplest proteinogenic amino acid, have been detected in meteorites and comets, indicating an extraterrestrial origin for some prebiotic molecules.
However, the formation of peptides, short chains of α-amino acids linked by peptide bonds, under astrophysical conditions has remained unresolved. Here we show that the building blocks of proteins can form in interstellar ice analogues exposed to ionising radiation, without the presence of liquid water.
Using isotopically labelled glycine irradiated with protons at cryogenic temperatures, we detect the formation of glycylglycine, the simplest dipeptide, along with deuterated and non-deuterated water as by-products. Peptide bond formation is confirmed by infrared spectroscopy and high-resolution mass spectrometry, which also reveal the production of other complex organic species.
These findings demonstrate a non-aqueous route to peptide formation under space-like conditions and suggest that such molecules could form in the cold interstellar medium and be incorporated into forming planetary systems. Our results challenge aqueous-centric models of early biochemical evolution and broaden potential settings for the origins of life.
Alfred Thomas Hopkinson (1), Ann Mary Wilson (1), Joe Pitfield (1), Alejandra Traspas Muiña (2), Richárd Rácz (3), Duncan V. Mifsud (3), Péter Herczku (3), Gergő Lakatos (3 and 4 and 5), Béla Sulik (3), Zoltán Juhász (3), Sándor Biri (3), Robert W. McCullough (6), Nigel J. Mason (6 and 7), Carsten Scavenius (8), Liv Hornekær (1 and 9), Sergio Ioppolo (1) ((1) Center for Interstellar Catalysis, Aarhus University, (2) School of Electronic Engineering and Computer Science, Queen Mary University of London, (3) HUNREN Institute for Nuclear Research (Atomki), (4) Institute of Chemistry, University of Debrecen, (5) Doctoral School of Chemistry, University of Debrecen, (6) Department of Physics and Astronomy, School of Mathematics and Physics, Queens University Belfast, (7) Centre for Astrophysics and Planetary Science (CAPS), School of Physics and Astronomy, University of Kent, (8) Department of Molecular Biology and Genetics Protein Science, Aarhus University, (9) Interdisciplinary Nanoscience Center, Aarhus University)
Comments: 22 pages, 6 figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Space Physics (physics.space-ph)
Cite as: arXiv:2607.26814 [astro-ph.SR] (or arXiv:2607.26814v1 [astro-ph.SR] for this version)
https://doi.org/10.48550/arXiv.2607.26814
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Journal reference: Hopkinson, A.T., Wilson, A.M., Pitfield, J. et al. An interstellar energetic and non-aqueous pathway to peptide formation. Nat Astron 10, 531 539 (2026)
Related DOI:
https://doi.org/10.1038/s41550-025-02765-7
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Submission history
From: Alfred Hopkinson
[v1] Wed, 29 Jul 2026 12:03:44 UTC (5,338 KB)
https://arxiv.org/abs/2607.26814
Astrobiology,
