近日，刊登在国际杂志Astrobiology上的一项研究论文中，来自日本东京工业大学的科研人员利用结构生成软件发现了一种在核糖核酸（RNA）和脱氧核糖核酸（DNA）之前存在的特殊类型的核酸。
生命的两种基本单元：DNA和RNA都是由携带遗传信息的核酸组成，RNA是一种由重复的多个核苷酸单体形成的多聚体，而核苷酸自身则是由核糖链和氮杂环组成，RNA被认为是一种原始分子，而很多研究人员也表示，揭示RNA的起源或可帮助理解生命的起源，尽管RNA扮演着重要的角色，但很少有研究阐明RNA到底来自哪里，截至目前并没有研究成功可以成功利用简单的原始物质进行一步反应来产生RNA，因此这就意味着在RNA出现之前就已经存在简单的核酸物质了。
文章中，研究者检测了所有RNA核苷的可能性同分异构体，他们想去研究确定RNA来自于那种形式的空间结构，结果表明，在转变成为生物体的重要分子之前，RNA或许就已经完成了同多种其它结构的竞争。利用结构生成的软件，研究者Cleaves揭开了227个RNA异构体的结构以及许多简单的类似物，这些异构体和类似物或许可以作为形成RNA样分子的结构单元，随后研究者经过对来自核糖核苷结构公式的结构进行仔细筛选，最终选择出了特殊的结构，这种特殊结构在特殊情况下会保持稳定，比如适度pH值、温度等。
RNA在细胞中传输遗传信息上扮演着重要作用，而且很可能RNA和DNA的不断进化就是为了制定出完成其任务的最佳方法，从而给予特定的参数，比如在细胞中的功能以及稳定性等；截止到目前为止，研究者在实验室中利用简单的生命起源前材料并不可能进行一部反应就得到RNA单体。
在这项研究中，研究人员首次尝试对RNA的结构空间进行定义，从而阐明核糖核苷的可能性同分异构体，而这些异构体以RNA类型分子为基础；文章中，研究者揭开了在适度环境中幸存的227种结构，其和RNA具有相似的功能，而很多种结构都从来没有被科学地描述或研究过。
最后研究者表示，在生物进化期间，RNA分子可能会同其它大量的可替代的核酸分子相互竞争来成为今日的关键核酸分子，而交替进化的结果或许会在其它星球中发生，研究者表示，未来研究中他们将通过更为深入的研究来揭示RNA的起源，这对于真正理解生命起源的分子机体或提供了新的线索。
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227 Views of RNA: Is RNA Unique in Its Chemical Isomer Space?
Cleaves H. James II, Meringer Markus, and Goodwin Jay.
Ribonucleic acid (RNA) is one of the two nucleic acids used by extant biochemistry and plays a central role as the intermediary carrier of genetic information in transcription and translation. If RNA was involved in the origin of life, it should have a facile prebiotic synthesis. A wide variety of such syntheses have been explored. However, to date no one-pot reaction has been shown capable of yielding RNA monomers from likely prebiotically abundant starting materials, though this does not rule out the possibility that simpler, more easily prebiotically accessible nucleic acids may have preceded RNA. Given structural constraints, such as the ability to form complementary base pairs and a linear covalent polymer, a variety of structural isomers of RNA could potentially function as genetic platforms. By using structure-generation software, all the potential structural isomers of the ribosides (BC5H9O4, wher B is nucleobase), as well as a set of simpler minimal analogues derived from them, that can potentially serve as monomeric building blocks of nucleic acid–like molecules are enumerated. Molecules are seleced based on their likely stability under biochemically relevant conditions (e.g., moderate pH and temperature) and the presence of at least two functional groups allowing the monomers to be incorporated into linear polymers. The resulting structures are then evaluated by using molecular descriptors typically applied in quantitative structure–property relationship (QSPR) studies and predicted physicochemical properties. Several databases have been queried to determine whether any of the computed isomers had been synthesized previously. Very few of the molecules that emerge from this structure set have been previously described. We conclude that ribonucleosides may have competed with a multitude of alternative structures whose potential proto-biochemical roles and abiotic syntheses remain to be explored. Key Words: Evolution—Chemical evolution—Exobiology—Prebiotic chemistry—RNA world.