Nucleobase and amino acid formation through impacts of meteorites on the early ocean
Nucleobase and amino acid formation through impacts of meteorites on the early ocean
复制标题
DOI：
10.1016/j.epsl.2015.07.049
复制
发表时间：
2015-11-01
影响因子：
5.3
通讯作者：
Kakegawa, Takeshi
中科院分区：
文献类型：
--
作者：
Furukawa, Yoshihiro;Nakazawa, Hiromoto;Kakegawa, Takeshi
生命的基石在生前地球上的出现是生命起源的第一个关键步骤。由于在看似合理的益生菌条件下从陆地的碳和氮源生产这些有机物存在困难，因此完整的氨基酸和碱基对地外输送是它们在益生菌地球上可利用的流行假说。然而，陨石运送的这些完整有机物的种类和数量将是有限的。以前的冲击恢复实验已经证明，陨石撞击反应可能在地球上产生了有机体。在这里，我们报告了在模拟外星人撞击早期海洋的反应的实验中，在DNA和/或RNA中发现的核碱基(胞嘧啶和尿嘧啶)、各种蛋白质产生的氨基酸(甘氨酸、丙氨酸、丝氨酸、天冬氨酸、谷氨酸、缬氨酸、亮氨酸、异亮氨酸和脯氨酸)、非蛋白质产生的氨基酸和脂肪胺的同时形成。据我们所知，这是第一个关于在冲击条件下从无机材料中形成碱基的报道。在这些实验中，重碳酸盐被用作碳源。碳酸氢盐是富含二氧化碳的大气条件下常见的溶解碳物种，据推测，它是早期海洋和撞击后羽流中最丰富的碳物种。因此，目前的结果扩大了这样一种可能性，即撞击引发的反应通过使用陆地碳库，大量地为地球上的生命创造了各种构件。(C)2015爱思唯尔B.V.保留所有权利。
The emergence of life's building blocks on the prebiotic Earth was the first crucial step for the origins of life. Extraterrestrial delivery of intact amino acids and nucleobases is the prevailing hypothesis for their availability on prebiotic Earth because of the difficulties associated with the production of these organics from terrestrial carbon and nitrogen sources under plausible prebiotic conditions. However, the variety and amounts of these intact organics delivered by meteorites would have been limited. Previous shock-recovery experiments have demonstrated that meteorite impact reactions could have generated organics on the prebiotic Earth. Here, we report on the simultaneous formation of nucleobases (cytosine and uracil) found in DNA and/or RNA, various proteinogenic amino acids (glycine, alanine, serine, aspartic acid, glutamic acid, valine, leucine, isoleucine, and proline), non-proteinogenic amino acids, and aliphatic amines in experiments simulating reactions induced by extraterrestrial objects impacting on the early oceans. To the best of our knowledge, this is the first report of the formation of nucleobases from inorganic materials by shock conditions. In these experiments, bicarbonate was used as the carbon source. Bicarbonate, which is a common dissolved carbon species in CO2-rich atmospheric conditions, was presumably the most abundant carbon species in the early oceans and in post-impact plumes. Thus, the present results expand the possibility that impact-induced reactions generated various building blocks for life on prebiotic Earth in large quantities through the use of terrestrial carbon reservoirs. (C) 2015 Elsevier B.V. All rights reserved.