Peptide Synthesis under the Alkaline Hydrothermal Conditions on Enceladus

Wataru Takahagi, Kaito Seo, Takazo Shibuya, Yoshinori Takano, Kosuke Fujishima, Masafumi Saitoh, Shigeru Shimamura, Yohei Matsui, Masaru Tomita, Ken Takai

Research output: Contribution to journalArticle

Abstract

Chemical evolution is an abiotic reaction process in which complex organic molecules arise from a combination of simple inorganic and organic chemical compounds. To assess the possible ongoing chemical evolution in the subsurface ocean of Saturn's icy satellite Enceladus, we explored the water-rock aqueous reactions and the peptide formation capability under a hydrothermal environment similar to that on Enceladus. It has been suggested that the core of Enceladus has not experienced high temperatures from the time of satellite formation to the present. The major components of the core are assumed to be carbonaceous chondrites; thus, simple organic substances, including amino acids, are likely present in the alkaline seawater of Enceladus. In this study, we conducted a laboratory-based simulation experiment to describe the chemical alteration of six prebiotically abundant amino acids over 147 days under high pressure with thermal cycling (30 to 100 °C) to simulate the water-rock interface of the ocean on Enceladus. As a result, we detected 28 out of 36 possible dipeptide species during the entire reaction period. We propose that peptide-bond formation is coupled to rock surface chemisorption of amino acids under alkaline condition, which was further supported by the elemental analysis showing carbon and nitrogen signature on the rock surface only when amino acids are added. The above result suggests that ongoing chemical evolution on Enceladus is likely producing short abiotic peptides on the porous core surface.

Original languageEnglish
JournalACS Earth and Space Chemistry
DOIs
Publication statusAccepted/In press - 2019 Jan 1

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Keywords

  • Enceladus
  • Hydrothermal System
  • Molecular Evolution
  • Peptide Synthesis
  • Water-Rock Interaction

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Atmospheric Science
  • Space and Planetary Science

Cite this

Takahagi, W., Seo, K., Shibuya, T., Takano, Y., Fujishima, K., Saitoh, M., Shimamura, S., Matsui, Y., Tomita, M., & Takai, K. (Accepted/In press). Peptide Synthesis under the Alkaline Hydrothermal Conditions on Enceladus. ACS Earth and Space Chemistry. https://doi.org/10.1021/acsearthspacechem.9b00108