In a groundbreaking development that challenges conventional understanding of chemistry and the origins of life, a recent study reveals that peptides—the fundamental building blocks of proteins—can form in the harsh environments of interstellar space without the presence of liquid water. This discovery overturns long-held assumptions that aqueous environments are prerequisites for peptide bond formation, extending the possibilities for how life’s essential molecules might arise across the cosmos.
Peptides, chains of amino acids linked via peptide bonds, are critical components of biology on Earth. Until now, their formation was understood primarily as a process dependent on liquid water, a solvent known to facilitate chemical reactions on our planet. However, new experimental evidence demonstrates that simple peptides such as glycylglycine—the smallest dipeptide—can form within interstellar ice analogues subjected to ionizing radiation at cryogenic temperatures. This insight opens a remarkable non-aqueous pathway to molecular complexity in space.
The study by Hopkinson et al. utilizes isotopically labelled glycine, the simplest proteinogenic amino acid, embedded in laboratory-created ices mimicking interstellar conditions. By exposing these ices to proton irradiation simulating cosmic rays, researchers observed chemical transformations that culminated in peptide bond formation. The experiments were conducted at temperatures close to absolute zero, mirroring the frigid vacuum of molecular clouds where stars and planetary systems eventually form.
This research leverages advanced infrared spectroscopy and high-resolution mass spectrometry to confidently confirm the presence of glycylglycine. The spectroscopic signatures revealed not only the peptide bonds but also an array of other complex organic molecules, creating a vivid molecular tapestry within the frozen simulants. Interestingly, alongside the peptides, both deuterated and hydrogen-containing water molecules emerged as reaction by-products, hinting at a rich chemical interplay under these extreme conditions.
The implications of this study extend far beyond pure chemistry. For decades, scientists have debated the extraterrestrial origins of life’s molecular precursors. While amino acids have been found in meteorites and comets, providing tantalizing evidence that the ingredients for life are widespread, the leap from amino acid monomers to peptides remained elusive without liquid water. Now, these findings propose that cold, radiation-driven chemistry within icy grain mantles in interstellar space may foster the initial steps toward biopolymers.
The energetics of ionizing radiation appear pivotal in overcoming the substantial activation barriers for peptide bond formation. Unlike terrestrial chemistry where enzymes or catalytic surfaces assist in peptide synthesis, in interstellar ices, energetic protons induce radical reactions and molecular rearrangements within the rigid lattice of frozen material. This mechanism suggests a hitherto underappreciated pathway for complexity to emerge from simplicity in the cold cosmos.
Furthermore, the incorporation of isotopic labelling techniques allowed the researchers to discern the exact origin of atoms within the peptides and accompanying water molecules, ruling out contamination and underscoring the authentic abiotic nature of the reactions. The sophistication of these analytical methods lends robust confidence to the conclusion that peptide formation is not limited to terrestrial or aqueous environments.
Astrobiologists and chemists alike must now reconsider the early chemical evolution scenarios of the universe. The interstellar medium, once considered a sterile cold vacuum, emerges as an active chemical factory capable of assembling complex organic molecules vital to life. The presence of peptides in space-bound ices suggests that nascent planetary systems might inherit these building blocks, potentially seeding nascent worlds with prebiotic material before water-based chemistry even begins.
This research also challenges the aqueous-centric paradigms that have dominated theories of biochemical origins. It opens up engaging questions about the adaptability and diversity of chemical pathways that can lead to life. Could life’s molecular precursors even form and persist in other environments thought too extreme or dry? The study broadens the scope of astrobiological environments considered habitable or conducive to prebiotic chemistry.
Moreover, such a radiation-driven, non-aqueous synthetic route to peptides may influence future research into the chemical inventory of comets, meteorites, and planetary ices. Astrophysical surveys that detect organic molecules in space might now focus on seeking peptide signatures, potentially transforming our understanding of how widespread these polymers are throughout the galaxy.
Importantly, this work exemplifies the synergy between laboratory astrochemistry and space exploration. By replicating extreme space conditions, scientists can infer plausible chemical evolution pathways that are otherwise impossible to observe directly in distant interstellar clouds. These complementary approaches ensure that theoretical models remain anchored in empirical evidence.
The detection of glycylglycine and related peptides in such alien conditions not only informs our chemical prehistory but also offers a new lens through which to view the emergence of biologically relevant molecules. It raises the provocative possibility that life’s molecular antecedents may be cosmic rather than strictly planetary in origin, transported across space and time embedded within icy bodies.
Given the prevalence of cosmic rays and the abundance of icy grains in molecular clouds, peptide formation via this energetic, non-aqueous route could be a widespread process, occurring throughout our galaxy and beyond. This insight affirms a universality of chemical evolution pathways, where the universe itself fosters molecular complexity in surprising ways.
Beyond its scientific significance, this discovery captures the imagination by extending the frontier of prebiotic chemistry to the coldest, darkest reaches of space. It suggests that life’s molecular seeds might be sown far and wide, carried on interstellar winds and stellar debris, waiting for the right planetary cradle to bloom.
The team’s findings are poised to inspire a new generation of experiments and astrophysical observations aimed at unraveling the mysteries of life’s cosmic origins. From laboratory benches to telescopes scanning distant star-forming regions, humanity’s quest to understand our molecular roots gains a fresh, exhilarating chapter with this research.
In essence, this study not only redefines the chemistry of the cosmos but also expands the narrative of life’s beginnings, blending cutting-edge experimental innovation with profound philosophical questions about our place in the universe.
Subject of Research: Formation of peptides under interstellar ice analogue conditions via ionizing radiation, elucidating non-aqueous pathways to prebiotic molecules in space.
Article Title: An interstellar energetic and non-aqueous pathway to peptide formation.
Article References:
Hopkinson, A.T., Wilson, A.M., Pitfield, J. et al. An interstellar energetic and non-aqueous pathway to peptide formation. Nat Astron (2026). https://doi.org/10.1038/s41550-025-02765-7
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