The formation of polymers that can hold gene information and work as catalysts is a crucial step for the origin of life. The discovery of catalytic RNA (i.e., ribozyme) supports the hypothesis that RNA might have served these functions at the early stage of life on the Earth. Given this, the spontaneous formation of RNA monomers (i.e., ribonucleotides) and their polymerization on Hadean Earth are essential steps for the origin of life. Previous experiments have investigated the chemical reactions that allow the formation of ribonucleotides and their components. These works have revealed the required molecules to form biological ribonucleotides (i.e., canonical ribonucleotides). Based on geochemical perspectives, abundantly available reactive molecules spontaneously react with each other to provide abundant products. Aldehydes and ammonia are reactive molecules assumed to have been present in considerable amounts on Hadean Earth. However, little is understood about whether or not nucleotides and their components were formed from these molecules under prebiotic conditions. We investigated the incubation products of alkaline aqueous solutions of aldehydes and ammonia. The product solution contained sugars (including ribose), various imidazole derivatives, and ribosyl imidazole (i.e., imidazole ribonucleoside). Ribosyl imidazole is formed via ribosyl amine, which reveals a new reaction pathway for prebiotic ribonucleoside synthesis. The imidazole ribonucleoside was then phosphorylated to imidazole ribonucleotide via a simple dry-down reaction with phosphate. Borate ion improved the reaction yields of these nucleosides and nucleotides. Because all the reactants were available on prebiotic Earth and the reactions progressed spontaneously, imidazole ribonucleotides could have accumulated in prebiotic environments. The experimental simplicity of the present reaction suggests that imidazoles were more abundant than canonical nucleobases on the prebiotic Earth. This further implies that prebiotic oligonucleotides contained imidazole bases in addition to the canonical nucleobases. The improvement of the reaction yields by borate indicates that borate-rich environments were conducive places for the formation and accumulation of non-canonical nucleosides and nucleotides. Such environments could have facilitated the formation of primordial ribonucleic acids on Hadean Earth.

中文翻译：

---

在益生元地球条件下，从醛和氨中一锅法合成非经典核糖核苷及其前体


形成可以保存基因信息并作为催化剂的聚合物是生命起源的关键步骤。催化 RNA（即核酶）的发现支持 RNA 可能在地球生命的早期阶段发挥这些功能的假设。鉴于此，RNA 单体（即核糖核苷酸）的自发形成及其在 Hadean Earth 上的聚合是生命起源的重要步骤。以前的实验已经研究了允许形成核糖核苷酸及其成分的化学反应。这些工作揭示了形成生物核糖核苷酸（即经典核糖核苷酸）所需的分子。基于地球化学的观点，大量可用的反应分子自发地相互反应，提供丰富的产物。醛和氨是据推测在 Hadean Earth 上大量存在的反应性分子。然而，对于核苷酸及其成分是否是在益生元条件下由这些分子形成的，人们知之甚少。我们研究了醛和氨的碱性水溶液的孵育产物。产品溶液含有糖（包括核糖）、各种咪唑衍生物和核糖基咪唑（即咪唑核糖核苷）。核糖基咪唑是通过核糖基胺形成的，这揭示了益生元核糖核苷合成的新反应途径。然后通过与磷酸盐进行简单的干燥反应，将咪唑核糖核苷磷酸化为咪唑核糖核苷酸。硼酸根离子提高了这些核苷和核苷酸的反应产率。 因为所有反应物都在益生元地球上可用，而且反应是自发进行的，所以咪唑核糖核苷酸可能已经在益生元环境中积累。当前反应的实验简单性表明，咪唑在益生元地球上比经典核碱基更丰富。这进一步意味着益生元寡核苷酸除了经典核碱基外，还含有咪唑碱基。硼酸盐反应产率的提高表明，富含硼酸盐的环境有利于非经典核苷和核苷酸的形成和积累。这样的环境可能促进了 Hadean Earth 上原始核糖核酸的形成。