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A non-energetic mechanism for glycine formation in the interstellar medium


The detection of the amino acid glycine and its amine precursor methylamine on the comet 67P/Churyumov-Gerasimenko by the Rosetta mission provides strong evidence for a cosmic origin of amino acids on Earth. How and when such molecules form along the process of star formation remains debated. Here we report the laboratory detection of glycine formed in the solid phase through atom and radical–radical addition surface reactions under dark interstellar cloud conditions. Our experiments, supported by astrochemical models, suggest that glycine forms without the need for ‘energetic’ irradiation (such as ultraviolet photons and cosmic rays) in interstellar water-rich ices, where it remains preserved, during a much earlier star-formation stage than previously assumed. We also confirm that solid methylamine is an important side-reaction product. A prestellar formation of glycine on ice grains provides the basis for a complex and ubiquitous prebiotic chemistry in space enriching the chemical content of planet-forming material.

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Fig. 1: Schematic of surface reaction routes leading to the formation of glycine in a water-rich ice during early stages of low-mass stellar evolution.
Fig. 2: QMS-TPD data of four equivalent laboratory experiments on the surface formation of glycine and its isotopologues.
Fig. 3: QMS-TPD data of non-fragmented glycine formed at 13 K and desorbed at 245 K.
Fig. 4: RAIR data showing the presence of glycine ice in experiment 1.
Fig. 5: Abundances of solid species, including glycine and species involved in its surface formation, with respect to gas-phase H during the collapse of a prestellar core from Model 2.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

Code availability

The codes for Models 1 and 2 are proprietary, but the input and output data are available from the corresponding author upon request.


  1. 1.

    Elsila, J. E., Glavin, D. P. & Dworkin, J. P. Cometary glycine detected in samples returned by Stardust. Meteorit. Planet. Sci. 44, 1323–1330 (2009).

    ADS  Google Scholar 

  2. 2.

    Altwegg, K. et al. Prebiotic chemicals—amino acid and phosphorus—in the coma of comet 67P/Churyumov-Gerasimenko. Sci. Adv. 2, e1600285 (2016).

    ADS  Google Scholar 

  3. 3.

    Cronin, J. R. & Pizzarello, S. Enantiomeric excesses in meteoritic amino acids. Science 275, 951–955 (1997).

    ADS  Google Scholar 

  4. 4.

    Botta, O., Glavin, D. P., Kminek, G. & Bada, J. L. Relative amino acid concentrations as a signature for parent body processes of carbonaceous chondrites. Orig. Life Evol. Biosph. 32, 143–163 (2002).

    ADS  Google Scholar 

  5. 5.

    Cobb, A. K. & Pudritz, R. E. Nature’s starships. I. Observed abundances and relative frequencies of amino acids in meteorites. Astrophys. J. 783, 140–151 (2014).

    ADS  Google Scholar 

  6. 6.

    Hadraoui, K. et al. Distributed glycine in comet 67P/Churyumov-Gerasimenko. Astron. Astrophys. 630, A32 (2019).

    Google Scholar 

  7. 7.

    Hoppe, P., Rubin, M. & Altwegg, K. Presolar isotopic signatures in meteorites and comets: new insights from the Rosetta mission to comet 67P/Churyumov-Gerasimenko. Space Sci. Rev. 214, 106–133 (2018).

    ADS  Google Scholar 

  8. 8.

    Altwegg, K. et al. Organics in comet 67P—a first comparative analysis of mass spectra from ROSINA-DFMS, COSAC and Ptolemy. Mon. Not. R. Astron. Soc. 469, S130–S141 (2017).

    Google Scholar 

  9. 9.

    Bernstein, M. P., Dworkin, J. P., Sandford, S. A., Cooper, G. W. & Allamandola, L. J. Racemic amino acids from the ultraviolet photolysis of interstellar ice analogues. Nature 416, 401–403 (2002).

    ADS  Google Scholar 

  10. 10.

    Muñoz Caro, G. M. et al. Amino acids from ultraviolet irradiation of interstellar ice analogues. Nature 416, 403–406 (2002).

    ADS  Google Scholar 

  11. 11.

    Woon, D. E. Pathways to glycine and other amino acids in ultraviolet-irradiated astrophysical ices determined via quantum chemical modeling. Astrophys. J. Lett. 571, L177–L180 (2002).

    ADS  Google Scholar 

  12. 12.

    Ciesla, F. J. & Sandford, S. A. Organic synthesis via irradiation and warming of ice grains in the solar nebula. Science 336, 452–454 (2012).

    ADS  Google Scholar 

  13. 13.

    Bossa, J.-B. et al. Methylammonium methylcarbamate thermal formation in interstellar ice analogs: a glycine salt precursor in protostellar environments. Astron. Astrophys. 506, 601–608 (2009).

    ADS  Google Scholar 

  14. 14.

    Garrod, R. T. A three-phase chemical model of hot cores: the formation of glycine. Astrophys. J. 765, 60–88 (2013).

    ADS  Google Scholar 

  15. 15.

    Sato, A. et al. First-principles study of the formation of glycine-producing radicals from common interstellar species. Mol. Astrophys. 10, 11–19 (2018).

    ADS  Google Scholar 

  16. 16.

    Gerakines, P. A. & Hudson, R. L. The radiation stability of glycine in solid CO2—in situ laboratory measurements with applications to Mars. Icarus 252, 466–472 (2015).

    ADS  Google Scholar 

  17. 17.

    Maté, B., Tanarro, I., Escribano, R., Moreno, M. A. & Herrero, V. J. Stability of extraterrestrial glycine under energetic particle radiation estimated from 2 keV electron bombardment experiments. Astrophys. J. 806, 151–160 (2015).

    ADS  Google Scholar 

  18. 18.

    Ceccarelli, C., Loinard, L., Castets, A., Faure, A. & Lefloch, B. Search for glycine in the solar type protostar IRAS 16293-2422. Astron. Astrophys. 362, 1122–1126 (2000).

    ADS  Google Scholar 

  19. 19.

    Jiménez -Serra, I., Testi, L., Caselli, P. & Viti, S. Detectability of glycine in solar-type system precursors. Astrophys. J. Lett. 787, L33–L37 (2014).

    ADS  Google Scholar 

  20. 20.

    Drozdovskaya, M. N., van Dishoeck, E. F., Rubin, M., Jørgensen, J. K. & Altwegg, K. Ingredients for solar-like systems: protostar IRAS 16293-2422 B versus comet 67P/Churyumov-Gerasimenko. Mon. Not. R. Astron. Soc. 490, 50–79 (2019).

    ADS  Google Scholar 

  21. 21.

    Kaifu, N. et al. Detection of interstellar methylamine. Astrophys. J. Lett. 191, L135–L137 (1974).

    ADS  Google Scholar 

  22. 22.

    Bøgelund, E. G., McGuire, B. A., Hogerheijde, M. R., van Dishoeck, E. F. & Ligterink, N. F. W. Methylamine and other simple N-bearing species in the hot cores NGC 6334I MM1-3. Astron. Astrophys. 624, A82 (2019).

    Google Scholar 

  23. 23.

    Ohishi, M., Suzuki, T., Hirota, T., Saito, M. & Kaifu, N. Detection of a new methylamine (CH3NH2) source: candidate for future glycine surveys. Publ. Astron. Soc. Jpn 71, 86–96 (2019).

    ADS  Google Scholar 

  24. 24.

    Boogert, A. C. A., Gerakines, P. A. & Whittet, D. C. B. Observations of the icy universe. Annu. Rev. Astron. Astrophys. 53, 541–581 (2015).

    ADS  Google Scholar 

  25. 25.

    Krasnokutski, S. A., Jäger, C. & Henning, T. Condensation of atomic carbon: possible routes toward glycine. Astrophys. J. 889, 67–73 (2020).

    ADS  Google Scholar 

  26. 26.

    Chuang, K.-J., Fedoseev, G., Ioppolo, S., van Dishoeck, E. F. & Linnartz, H. H-atom addition and abstraction reactions in mixed CO, H2CO and CH3OH ices—an extended view on complex organic molecule formation. Mon. Not. R. Astron. Soc. 455, 1702–1712 (2016).

    ADS  Google Scholar 

  27. 27.

    Fedoseev, G. et al. Formation of glycerol through hydrogenation of CO ice under prestellar core conditions. Astrophys. J. 842, 52–60 (2017).

    ADS  Google Scholar 

  28. 28.

    Goumans, T. P. M., Uppal, M. A. & Brown, W. A. Formation of CO2 on a carbonaceous surface: a quantum chemical study. Mon. Not. R. Astron. Soc. 384, 1158–1164 (2008).

    ADS  Google Scholar 

  29. 29.

    Ioppolo, S., Cuppen, H. M., Romanzin, C., van Dishoeck, E. F. & Linnartz, H. Laboratory evidence for efficient water formation in interstellar ices. Astrophys. J. 686, 1474–1479 (2008).

    ADS  Google Scholar 

  30. 30.

    Hidaka, H., Watanabe, M., Kouchi, A. & Watanabe, N. FTIR study of ammonia formation via the successive hydrogenation of N atoms trapped in a solid N2 matrix at low temperatures. Phys. Chem. Chem. Phys. 13, 15798–15802 (2011).

    Google Scholar 

  31. 31.

    Qasim, D. et al. An experimental study of the surface formation of methane in interstellar molecular clouds. Nat. Astron 4, 781–785 (2020).

    ADS  Google Scholar 

  32. 32.

    Theule, P. et al. Hydrogenation of solid hydrogen cyanide HCN and methanimine CH2NH at low temperature. Astron. Astrophys. 534, A64 (2011).

    Google Scholar 

  33. 33.

    Bossa, J.-B., Borget, F., Duvernay, F., Theulé, P. & Chiavassa, T. How a usual carbamate can become an unusual intermediate: a new chemical pathway to form glycinate in the interstellar medium. J. Phys. Org. Chem. 23, 333–339 (2010).

    Google Scholar 

  34. 34.

    Ioppolo, S., van Boheemen, Y., Cuppen, H. M., van Dishoeck, E. F. & Linnartz, H. Surface formation of CO2 ice at low temperatures. Mon. Not. R. Astron. Soc. 413, 2281–2287 (2011).

    ADS  Google Scholar 

  35. 35.

    Fuchs, G. W. et al. Hydrogenation reactions in interstellar CO ice analogues: a combined experimental/theoretical approach. Astron. Astrophys. 505, 629–639 (2009).

    ADS  Google Scholar 

  36. 36.

    NIST Chemistry WebBook Standard Reference Database 69 (NIST, accessed 2020);

  37. 37.

    Chaabouni, H., Diana, S., Nguyen, T. & Dulieu, F. Thermal desorption of formamide and methylamine from graphite and amorphous water ice surfaces. Astron. Astrophys. 612, A47 (2018).

    ADS  Google Scholar 

  38. 38.

    Maté, B., Rodriguez-Lazcano, Y., Gálvez, Ó., Tanarro, I. & Escribano, R. An infrared study of solid glycine in environments of astrophysical relevance. Phys. Chem. Chem. Phys. 13, 12268–12276 (2011).

    Google Scholar 

  39. 39.

    Holtom, P. D., Bennett, C. J., Osamura, Y., Mason, N. J. & Kaiser, R. I. A combined experimental and theoretical study on the formation of the amino acid glycine (NH2CH2COOH) and its isomer (CH3NHCOOH) in extraterrestrial ices. Astrophys. J. 626, 940–952 (2005).

    ADS  Google Scholar 

  40. 40.

    Oba, Y., Chigai, T., Osamura, Y., Watanabe, N. & Kouchi, A. Hydrogen isotopic substitution of solid methylamine through atomic surface reactions at low temperatures: a potential contribution to the D/H ratio of methylamine in molecular clouds. Meteorit. Planet. Sci. 49, 117–132 (2014).

    ADS  Google Scholar 

  41. 41.

    Schuhmann, M. et al. CHO-bearing molecules in comet 67P/Churyumov-Gerasimenko. ACS Earth Space Chem. 3, 1854–1861 (2019).

    Google Scholar 

  42. 42.

    Cuppen, H. M. & Herbst, E. Simulation of the formation and morphology of ice mantles on interstellar grains. Astrophys. J. 668, 294–309 (2007).

    ADS  Google Scholar 

  43. 43.

    Garrod, R. T., Belloche, A., Müller, H. S. P. & Menten, K. M. Exploring molecular complexity with ALMA (EMoCA): simulations of branched carbon-chain chemistry in Sgr B2(N). Astron. Astrophys. 601, A48 (2017).

    ADS  Google Scholar 

  44. 44.

    Vasyunin, A. I., Caselli, P., Dulieu, F. & Jiménez-Serra, I. Formation of complex molecules in prestellar cores: a multilayer approach. Astrophys. J. 842, 33–50 (2017).

    ADS  Google Scholar 

  45. 45.

    Garrod, R. T. & Pauly, T. On the formation of CO2 and other interstellar ices. Astrophys. J. 735, 15–32 (2011).

    ADS  Google Scholar 

  46. 46.

    Jiménez -Serra, I. et al. The spatial distribution of complex organic molecules in the L1544 pre-stellar core. Astrophys. J. Lett. 830, L6–L13 (2016).

    ADS  Google Scholar 

  47. 47.

    Oba, Y., Watanabe, N., Osamura, Y. & Kouchi, A. Chiral glycine formation on cold interstellar grains by quantum tunneling hydrogen–deuterium substitution reactions. Chem. Phys. Lett. 634, 53–59 (2015).

    ADS  Google Scholar 

  48. 48.

    Ioppolo, S., Fedoseev, G., Lamberts, T., Romanzin, C. & Linnartz, H. SURFRESIDE2: an ultrahigh vacuum system for the investigation of surface reaction routes of interstellar interest. Rev. Sci. Instrum. 84, 073112 (2013).

    ADS  Google Scholar 

  49. 49.

    Tschersich, K. G., Fleischhauer, J. P. & Schuler, H. Design and characterization of a thermal hydrogen atom source. J. Appl. Phys. 104, 034908 (2008).

    ADS  Google Scholar 

  50. 50.

    Anton, R., Wiegner, T., Naumann, W., Liebmann, M. & Klein, C. Design and performance of a versatile, cost-effective microwave electron cyclotron resonance source for surface and thin film processing. Rev. Sci. Instrum. 71, 1177–1180 (2000).

    ADS  Google Scholar 

  51. 51.

    Lamberts, T., Fedoseev, G., Kästner, J., Ioppolo, S. & Linnartz, H. Importance of tunneling in H-abstraction reactions by OH radicals: the case of CH4 + OH studied through isotope-substituted analogs. Astron. Astrophys. 599, A132 (2017).

    ADS  Google Scholar 

  52. 52.

    Fedoseev, G., Cuppen, H. M., Ioppolo, S., Lamberts, T. & Linnartz, H. Experimental evidence for glycolaldehyde and ethylene glycol formation by surface hydrogenation of CO molecules under dense molecular cloud conditions. Mon. Not. R. Astron. Soc. 448, 1288–1297 (2015).

    ADS  Google Scholar 

  53. 53.

    Kofman, V., Witlox, M. J. A., Bouwman, J., ten Kate, I. L. & Linnartz, H. A multifunctional setup to record FTIR and UV-vis spectra of organic molecules and their photoproducts in astronomical ices. Rev. Sci. Instrum. 89, 053111 (2018).

    ADS  Google Scholar 

  54. 54.

    Cuppen, H. M., Karssemeijer, L. J. & Lamberts, T. The kinetic Monte Carlo method as a way to solve the master equation for interstellar grain chemistry. Chem. Rev. 113, 8840–8871 (2013).

    Google Scholar 

  55. 55.

    Simons, M. A. J., Lamberts, T. & Cuppen, H. M. Formation of COMs through CO hydrogenation on interstellar grains. Astron. Astrophys. 634, A52 (2020).

    ADS  Google Scholar 

  56. 56.

    Cuppen, H. M. et al. Grain surface models and data for astrochemistry. Space Sci. Rev. 212, 1–58 (2017).

    ADS  Google Scholar 

  57. 57.

    Penteado, E. M., Walsh, C. & Cuppen, H. M. Sensitivity analysis of grain surface chemistry to binding energies of ice species. Astrophys. J. 844, 71–83 (2017).

    ADS  Google Scholar 

  58. 58.

    Senevirathne, B., Andersson, S., Dulieu, F. & Nyman, G. Hydrogen atom mobility, kinetic isotope effects and tunneling on interstellar ices (Ih and ASW). Mol. Astrophys. 6, 59–69 (2017).

    ADS  Google Scholar 

  59. 59.

    Ásgeirsson, V., Jónsson, H. & Wikfeldt, K. T. Long-time scale simulations of tunneling-assisted diffusion of hydrogen on ice surfaces at low temperature. J. Phys. Chem. C 121, 1648–1657 (2017).

    Google Scholar 

  60. 60.

    Garrod, R. T. A new modified-rate approach for gas-grain chemical simulations. Astron. Astrophys. 491, 239–251 (2008).

    ADS  Google Scholar 

  61. 61.

    Kalvāns, J. The efficiency of photodissociation for molecules in interstellar ices. Mon. Not. R. Astron. Soc. 478, 2753–2765 (2018).

    ADS  Google Scholar 

  62. 62.

    Jin, M. & Garrod, R. T. Formation of complex organic molecules in cold interstellar environments through nondiffusive grain-surface and ice-mantle chemistry. Astrophys. J. Suppl. 249, 26–55 (2020).

    ADS  Google Scholar 

  63. 63.

    Le Roy, L. et al. Inventory of the volatiles on comet 67P/Churyumov-Gerasimenko from Rosetta/ROSINA. Astron. Astrophys. 583, A1 (2015).

    Google Scholar 

  64. 64.

    Gibb, E. L., Whittet, D. C. B., Boogert, A. C. A. & Tielens, A. G. G. M. Interstellar ice: the infrared space observatory legacy. Astrophys. J. Suppl. 151, 35–73 (2004).

    ADS  Google Scholar 

  65. 65.

    Linnartz, H., Ioppolo, S. & Fedoseev, G. Atom addition reactions in interstellar ice analogues. Int. Rev. Phys. Chem. 34, 205–237 (2015).

    Google Scholar 

  66. 66.

    Persson, M. V. Current view of protostellar evolution (ENG). Figshare (2014).

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We thank T. Lamberts and I. Jiménez-Serra for stimulating discussions. This research was funded through a VICI grant of the NWO (the Netherlands Organization for Scientific Research) and A-ERC grant number 291141 (CHEMPLAN). Financial support from the Danish National Research Foundation through the Center of Excellence ‘InterCat’ (Grant agreement no. DNRF150) and from NOVA (the Netherlands Research School for Astronomy) and the Royal Netherlands Academy of Arts and Sciences (KNAW) through a professor prize is acknowledged. S.I. acknowledges the Royal Society for financial support through the University Research Fellowship (grant number UF130409), the University Research Fellowship Renewal 2019 (grant number URF\R\191018), the Research Fellows Enhancement Award (grant number RGF\EA\180306) and the Holland Research School for Molecular Chemistry (HRSMC) for a travel grant. G.F. acknowledges financial support from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie actions grant agreement number 664931 and support from an ‘iALMA’ grant (CUP C52I13000140001) approved by MIUR (Ministero dell’Istruzione, dell’Universitá e della Ricerca). A.R.C. and R.T.G. thank the NASA Astrophysics Research and Analysis Research programme for funding through grant number NNX15AG07G. V.K. was funded by the NWO PEPSci (Planetary and ExoPlanetary Science) programme. This work benefited from collaborations within the framework of the FP7 ITN LASSIE consortium (grant number GA238258).

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S.I. initiated and managed the project and wrote the manuscript with assistance from H.L., H.M.C., A.R.C., R.T.G., G.F. and K.-J.C. E.F.v.D. linked the laboratory and modelling results to astronomical observations. S.I., K.-J.C., G.F., D.Q. and V.K. performed laboratory experiments. H.L. was responsible for laboratory management. H.M.C., A.R.C. and R.T.G. developed and ran kinetic Monte Carlo simulations. M.J. and R.T.G. developed and ran the gas–grain kinetics models. All authors contributed to data interpretation and commented on the paper.

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Correspondence to S. Ioppolo.

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Supplementary Information

Supplementary Figs. 1–8, Tables 1–5 and text.

Supplementary Data

Reaction network as included in Model 1.

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Ioppolo, S., Fedoseev, G., Chuang, KJ. et al. A non-energetic mechanism for glycine formation in the interstellar medium. Nat Astron 5, 197–205 (2021).

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