Characterization of extraterrestrial amino acid precursors in simulation experiment products and meteorites

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H02991
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Geochemistry/Cosmochemistry
• Research Institution: Yokohama National University
• Principal Investigator: Kobayashi Kensei 横浜国立大学, 大学院工学研究院, 教授 (20183808)
• Co-Investigator(Kenkyū-buntansha): 三田 肇 福岡工業大学, 工学部, 教授 (00282301) ; 神田 一浩 兵庫県立大学, 高度産業科学技術研究所, 教授 (20201452) ; 癸生川 陽子 横浜国立大学, 大学院工学研究院, 准教授 (70725374)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: アミノ酸前駆体 / 分子雲 / 隕石母天体 / 宇宙線 / 炭素質コンドライト / 高分子態複雑有機物 / 国際宇宙ステーション

Outline of Final Research Achievements

Amino acids have been detected in meteorites, which suggested that extraterrestrial organics could be important sources for the first life on Earth. Formation mechanisms of such amino acids have not been clear though the Strecker synthesis have been considered as a major one. We performed experiments simulating interstellar ices and meteorite parent bodies to characterize the amino acid precursors formed in such environments. When a frozen mixture of simulated interstellar media was irradiated with high energy heavy ions, not free amino acids but amino acid precursors were formed. Not small precursors such as aminonitriles and hydantoins, but complex precursors whose molecular weight were over some hundreds were found to be major amino acid precursors in the products. Stability of the precursors were examined by utilizing the International Space Station as well as on ground. The complex precursors were generally more stable than the small precursors in space environments.

Free Research Field

アストロバイオロジー

Academic Significance and Societal Importance of the Research Achievements

従来，生命の起源に至る化学進化は，まず小さい有機物が生成し，それらの反応により徐々に大きい分子が生成する，というような反応機構により説明されてきた。本研究では，隕石中の有機物の起源を星間および小天体内部に求め，その模擬実験によりアミノ酸の生成機構を調べたところ，メタノールなどの小分子から高エネルギー粒子線などにより分子量数百以上のアミノ酸前駆体が直接生成することが確認され，従来とは全く異なる化学進化の考え方が必要性が示唆された。