Synthesis of glycine-containing complexes in impacts of comets on early Earth


Delivery of prebiotic compounds to early Earth from an impacting comet is thought to be an unlikely mechanism for the origins of life because of unfavourable chemical conditions on the planet and the high heat from impact. In contrast, we find that impact-induced shock compression of cometary ices followed by expansion to ambient conditions can produce complexes that resemble the amino acid glycine. Our ab initio molecular dynamics simulations show that shock waves drive the synthesis of transient C–N bonded oligomers at extreme pressures and temperatures. On post impact quenching to lower pressures, the oligomers break apart to form a metastable glycine-containing complex. We show that impact from cometary ice could possibly yield amino acids by a synthetic route independent of the pre-existing atmospheric conditions and materials on the planet.

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Figure 1: The cumulative probability of impact for our simulated shock velocities.
Figure 2: Snapshots of the computational cell.
Figure 3: Simulated mass spectra of the C–N bonded molecules found during our simulations.
Figure 4: Mechanism for glycine–CO2 complex synthesis on expansion and cooling.


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This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory (LLNL) under Contract DE-AC52-07NA27344. The project 06-ERD-037 was funded by the Laboratory Directed Research and Development Program at LLNL. Computations were performed at LLNL using the massively parallel computers Thunder, ATLAS, uP, UM, UV, Gauss and Prism. We acknowledge L. Krauss for help with constructing the graphics in Figs 2 and  4.

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N.G. originated the central idea for this work and performed and analysed the simulations. E.J.R. is lead author for the MSST algorithm and helped write the paper. L.E.F. co-created the MSST algorithm, wrote the molecular analyser code and helped write this paper. I.W.K. helped with the initial equilibration simulations. A.M. performed the Gibbs free energy of reaction calculations.

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Correspondence to Nir Goldman or Evan J. Reed.

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The authors declare no competing financial interests.

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Goldman, N., Reed, E., Fried, L. et al. Synthesis of glycine-containing complexes in impacts of comets on early Earth. Nature Chem 2, 949–954 (2010).

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