マーチソン隕石の異星人の非ラセミックアミノ酸の同位体証拠

M H Engel¹, S A Macko

¹School of Geology and Geophysics, The University of Oklahoma, Norman 73019, USA. AB1635@OU.EDU

Nature

|September 26, 1997

まとめ

初期の地球のアミノ酸は,地球外の起源を持っている可能性があります. マーチソン隕石はL-エナントイオマーの過剰を示しており,このヒラリティは地球上の生命より前のものであることを示唆しています.

科学分野:

天体生物学アストロバイオロジー
オーガニック・ジオケミストリーオーガニック・ジオケミストリー
生命の起源の研究生命の起源の研究

背景:

生命の構成要素であるアミノ酸は,L-およびD-エナチオマーとして存在します.
初期の地球は,アビオティック合成からのラセミアミノ酸混合物を持っていると推定されています.
L-アミノ酸の生命における排他的な使用は,未だに解明されていない.

研究の目的:

地球外のアミノ酸におけるL-エナニオメールの過剰の起源を調査する.
隕石の衝突が,初期の地球におけるキラル不均衡を説明できるかどうかを判断する.
キラルアミノ酸の地球外の源を確認しました.

主な方法:

マーチソン隕石からの個々のアミノ酸エナティオメアの分析.
アミノ酸の安定同位体分析 (15N濃縮)
地球外のアミノ酸同位体組成と地球上の同位体の比較.

主要な成果:

マーチソン隕石のアミノ酸は,地上のサンプルと比較して15Nの濃縮を示しています.
この同位体シグネチャーは,観測されたL-エナニオメールの過剰が地球外の起源であることを確認しています.
隕石におけるL-エナントイオマーの過剰は,生命より前のヒラル・インベントリを示唆する.

結論:

隕石のような地外的な源は,初期の地球に非ラセミックなアミノ酸の混合物を供給した.
この地球外のL-エナントイオマーの過剰は,生命のホモキラリティに影響を与えたのかもしれない.
この発見は,生物系で観察されるキラルバイアスの地球外起源を支持する.

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