Discovery In Space Of Ethanolamine, The Simplest Phospholipid Head Group


Structure of cellular membranes. a) Schematic view of a cell; b) Zoom-in view of the cell membrane, formed by a phospholipid bilayer; c) Three-dimensional structure of the phospholipid phosphatidylethanolamine (PE), formed by a hydrophilic head composed of ethanolamine, a phosphate group linked to glycerol, and two hydrophobic fatty-acid tails (black, red, blue and white balls denote carbon, oxygen, nitrogen and hydrogen atoms, respectively); d) Ethanolamine (EtA), the molecular species detected in space for the first time and reported in this work.

Cell membranes are a key element of life because they keep the genetic material and metabolic machinery together. All present cell membranes are made of phospholipids, yet the nature of the first membranes and the origin of phospholipids are still under debate.

We report here the first detection in space of ethanolamine, NH2CH2CH2OH, which forms the hydrophilic head of the simplest and second most abundant phospholipid in membranes. The molecular column density of ethanolamine in interstellar space is N=(1.51±0.07)×1013 cm−2, implying a molecular abundance with respect to H2 of (0.9-1.4)×10−10. Previous studies reported its presence in meteoritic material but they suggested that it is synthesized in the meteorite itself by decomposition of amino acids.

However, we find that the proportion of the molecule with respect to water in the interstellar medium is similar to the one found in the meteorite (10−6). These results indicate that ethanolamine forms efficiently in space and, if delivered onto early Earth, it could have contributed to the assembling and early evolution of primitive membranes.

Víctor M. Rivilla, Izaskun Jiménez-Serra, Jesús Martín-Pintado, Carlos Briones, Lucas F. Rodríguez-Almeida, Fernando Rico-Villas, Belén Tercero, Shaoshan Zeng, Laura Colzi, Pablo de Vicente, Sergio Martín, Miguel A. Requena-Torres

Comments: Accepted in PNAS (Proceedings of the National Academy of Sciences of the United States of America)
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
DOI: 10.1073/pnas.2101314118
Cite as: arXiv:2105.11141 [astro-ph.GA] (or arXiv:2105.11141v1 [astro-ph.GA] for this version)
Submission history
From: Victor Manuel Rivilla
[v1] Mon, 24 May 2021 08:02:35 UTC (775 KB)
https://arxiv.org/abs/2105.11141
Astrobiology, Astrochemistry,

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