Extraterrestrial ribose and other sugars in primitive meteorites
Extraterrestrial ribose and other sugars in primitive meteorites
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DOI：
10.1073/pnas.1907169116
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发表时间：
2019-12-03
影响因子：
11.1
通讯作者：
Nakamura, Tomoki
中科院分区：
文献类型：
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作者：
Furukawa, Yoshihiro;Chikaraishi, Yoshito;Nakamura, Tomoki
糖是所有陆地生物群在许多生物过程中工作的基本分子。核糖作为RNA的基本组成部分是特别重要的，RNA既可以存储信息，也可以催化地球上原始生命的反应。陨石含有许多有机化合物，包括生命的关键组成部分，即，氨基酸、核碱基和磷酸盐。在彗星样本中也发现了一种氨基酸。然而，外星生物重要糖的存在仍然不清楚。我们分析了3个碳质陨石中的糖，并显示了原始陨石中外星核糖和其他生物必需糖的证据。检测到的糖的C-13富集的稳定碳同位素组成（Δ C-13（vs.）VPDB）表明，糖是外星起源的。我们还进行了一个实验室模拟实验，在太空中潜在的糖形成反应。陨石中戊糖的组成和实验室模拟产物的组成表明，陨石糖是通过类似甲醛的过程形成的。这些陨石的矿物成分进一步表明，这些糖在其母小行星吸积之前和之后都有形成。陨石是早期地球生命前有机分子的载体;因此，在陨石中检测到外星糖建立了天然地质路线的存在，以制造和保存它们，并提高了外星糖有助于形成早期地球或其他原始世界的功能性生物聚合物的可能性。
Sugars are essential molecules for all terrestrial biota working in many biological processes. Ribose is particularly essential as a building block of RNA, which could have both stored information and catalyzed reactions in primitive life on Earth. Meteorites contain a number of organic compounds including key building blocks of life, i.e., amino acids, nucleobases, and phosphate. An amino acid has also been identified in a cometary sample. However, the presence of extraterrestrial bioimportant sugars remains unclear. We analyzed sugars in 3 carbonaceous chondrites and show evidence of extraterrestrial ribose and other bioessential sugars in primitive meteorites. The C-13-enriched stable carbon isotope compositions (delta C-13(vs. )VPDB) of the detected sugars show that the sugars are of extraterrestrial origin. We also conducted a laboratory simulation experiment of a potential sugar formation reaction in space. The compositions of pentoses in meteorites and the composition of the products of the laboratory simulation suggest that meteoritic sugars were formed by formose-like processes. The mineral compositions of these meteorites further suggest the formation of these sugars both before and after the accretion of their parent asteroids. Meteorites were carriers of prebiotic organic molecules to the early Earth; thus, the detection of extraterrestrial sugars in meteorites establishes the existence of natural geological routes to make and preserve them as well as raising the possibility that extraterrestrial sugars contributed to forming functional biopolymers like RNA on the early Earth or other primitive worlds.