This article is part of the Chemical Evolution and the Origins of Life special issue. Ramanarayanan Krishnamurthy was born in Chennai, India. He received his B.Sc. from Vivekananda College (University of Madras) and M.Sc. from the Indian Institute of Technology (IIT) in Bombay. He obtained his Ph.D. from The Ohio State University (OSU), under the guidance of David Hart. He was a postdoctoral researcher at the Swiss Federal Institute of Technology (ETH) in Zürich with Eschenmoser and was a NASA-NSCORT fellow with Gustaf Arrhenius at the Scripps Institution of Oceanography. He then rejoined Eschenmoser at the Skaggs Institute for Chemical Biology at the Scripps Research Institute in La Jolla, California, resulting in a 13-year collaborative partnership. He is currently an associate professor of chemistry at the Scripps Research Institute. He is a scientific collaborator with the NSF/NASA Center for Chemical Evolution (CCE) and a member of the Simons Collaboration on the Origins of Life (SCOL) and has been appointed as a colead of the Prebiotic Chemistry and Early Earth Environments (PCE3) Consortium, one of the five Research Coordination Networks within the NASA Astrobiology Program. Prof. Krishnamurthy was elected a fellow of the International Society for the Study of the Origin of Life in 2011. Nicholas Hud was born in Los Angeles, California. He received his B.S. degree from Loyola Marymount University. His Ph.D. was conferred by the University of California, Davis for physical investigations of DNA condensation by protamine in the laboratory of Prof. Rod Balhorn. He was an NIH postdoctoral fellow in biophysics at UCLA with Prof. Juli Feigon and Prof. Frank Anet. He joined the faculty of the School of Chemistry and Biochemistry at Georgia Tech in 1999 and was named Regents’ Professor in 2016. He currently serves as Director of the NSF/NASA Center for Chemical Evolution (CCE), and as Associate Director of the Parker H. Petit Institute of Bioengineering and Bioscience. Prof. Hud was elected Fellow of the American Association for the Advancement of Science in 2019 and Fellow of the International Society for the Study of the Origin of Life in 2014 and was a Sigma Xi Distinguished Lecturer in 2015–2017. Chemical evolution and the origins of life is a topic that spans and transcends many domains: all disciplines of science, eras, cultures, and even space.(1,2) It is a topic that enduringly captures the imagination of scientists and the general public alike.(3−5) Understanding how life arose on the Earth and elsewhere is a historical and reconstructive endeavor, but it is also very much a contemporary and ever-refreshing scientific undertaking.(6) These efforts have rich histories and have been driven by competing ideas ranging from protein-, RNA-, metabolism-, and lipid-world hypothesis to “far-out” ideas such as panspermia.(7−12) From the perspective of chemists this pursuit is focused on understanding how elements and molecules that accumulate on a young planet can transform—under the abiotic geochemical constraints—into self-assembling, self-sustaining interactive systems with emerging patterns and behavior, and begin to evolve into what could be considered as living entities.(13) From the viewpoint of astrochemistry, prebiotic-chemistry, and biochemistry, this thematic issue covers our current understanding of a spectrum of topics associated with the chemical origins of life. Along with their compilations of impressive advances, each contribution also acknowledges remaining unsolved problems and challenges that are to be faced as we aspire to address the grand question “Can the origins of life be demonstrated or understood experimentally?” While answering that question in a historically accurate context may be not possible, it is indeed within the grasp of chemists (with guidance from observations in astrochemistry, geological constraints of early Earth and its atmosphere, prebiotic organic chemistry and extant biochemistry) to demonstrate in the laboratory the transformations of molecules—by chemical reactions—to systems that approximate the behavior/phenomenon observed in biology.(14) Although this may fall short of “recreating life in a test tube”, it surely would be a more modest—but still a powerful—substantiation of the emergence and evolution of chemical processes that can lead to the origins of life. This thematic issue begins with Sandford and colleagues describing the Prebiotic Astrochemistry and the Formation of Molecules of Astrobiological Interest in Interstellar Clouds and Protostellar Disks, where planetary systems form, thus laying the foundation for chemical species that are available for processes leading to the origins of life on planets. If this process is indeed “universal” then questions arise about the possibility of extraterrestrial life elsewhere in the universe, and Sandford and colleagues suggest that life may be common where local conditions favor these chemical processes. With Earth being our only current example of a planet harboring life to guide our search for life elsewhere, there must be a set of criteria for life detection missions using our understanding of the essence and uniqueness of biology and its processes.(15) One such singularity of biology on the Earth is homochirality, including the use of l-amino acids and d-sugars of single-handedness.(16) However, using chiral asymmetry as a definitive biosignature is complicated by nonbiological processes that can interfere. Glavin et al. review the enantiomeric and isotopic compositions and distributions of molecules found in meteorites and propose a set of criteria for The Search for Chiral Asymmetry as a Potential Biosignature in our Solar System. These authors also present arguments for “sample return missions” that may represent our best chance to establish firmly the origins of chiral asymmetry as a potential biosignature of life elsewhere in our solar system. Once source molecules, such as amino acids, nucleobases, and sugar building blocks have been deposited (or formed in situ) on the early planet (e.g., Earth), the ensuing interactions and reactions between them leading to more complex molecules are hypothesized to be a natural part of the processes under geochemical constraints.(17) For example, phosphorylation, a central reaction in the metabolic, structural, and replicative processes in biology, is also widely assumed to have played an important role in jumpstarting chemical evolution toward life on the early Earth.(18) As Pasek points out, the Thermodynamics of Prebiotic Phosphorylation can be used to evaluate the likelihood of various sources, processes, and geochemical environments that enabled the conversion of inorganic phosphorus compounds to organic phosphates for further processing. Amino acids are prebiotically plausible compounds of the early Earth and are the building blocks of peptides and proteins, which are the catalytic engines of extant biology.(19) Prior to the emergence of coded protein enzymes, noncovalent interactions of prebiotic peptides could have played a key role in the emerging interconnected molecular networks. Ashkenasy, Leman and colleagues summarize mechanisms of how amino acids (and coexisting molecules) were transformed into peptides and protopeptides and discuss the early roles of Prebiotic Peptides as Molecular Hubs in the Origin of Life. Furthermore, they review the plausible interactions of prebiotic peptides (and protopeptides) with other classes of molecules, thereby emphasizing a systems chemistry approach(20) for synergistic interactions in chemical evolution. Another crucial class of molecules in life are nucleotides, the monomers of RNA and DNA, whose prebiotic availability is more challenging when compared to amino acids.(21) Nevertheless, the central role played by RNA in extant biology, especially of the ribosome in peptide synthesis, has forced the reckoning with an RNA world scenario on early Earth.(22) This powerful impetus has resulted in intensive efforts to fashion plausible prebiotic synthesis of canonical nucleotides. Krishnamurthy and colleagues review the current status the Chemistry of Abiotic Nucleotide Synthesis in a prebiotic context and point to the remaining challenges in elucidating pathways to the building blocks of RNA and DNA that are universally acceptable as prebiotically plausible in an early Earth geochemical context. The plethora of noncanonical products that are formed in many of the reactions that produce the canonical sugars (ribose) and nucleobases (A, U, G, and C), raises the question: Were alternative nucleosides and nucleotides involved in chemical evolution and the origins of life?(23)Hud et al. point out in their review, Prebiotic Syntheses of Noncanonical Nucleosides and Nucleotides, that alternative nucleobases, sugars, backbone linkers, and nucleosides/-tides would have been formed by similar or competing chemistries. More than the four canonical nucleotides for RNA, these alternative building blocks have the potential to give rise to self-assembling/functional alternative proto-RNA or pre-RNA candidates, whose roles need to be given serious consideration and evaluated in the chemical evolutionary processes and transitions leading to extant biopolymers on the early Earth.(24,25) In all of the above scenarios, the chirality of the building blocks must be considered, especially as one proceeds toward polymeric and supramolecular assemblies. How homochirality or one-handedness manifested in biology as d-sugars and l-amino acids is an extremely important, but far from understood, phenomenon.(26)Blackmond tackles this question by considering Autocatalytic Models for the Origin of Homochirality and discusses the Soai reaction (the only known example of an amplifying autocatalytic reaction) in depth as a model to examine whether a prebiotically plausible variant would be feasible. Increasingly, it appears that the emergence of homochirality is not determined by a single event but rather by a series of synergistical and sustained chemical and physical processes. While the historical details are still unclear, at some point evolution, chemical or biological, sorted out all that was necessary to make ribozymes, catalytic molecules encoded in RNA—as epitomized by the ribosome, which is responsible for coded-protein synthesis in all living systems.(27)Williams and colleagues, in their review, Root of the Tree: The Significance, Evolution, and Origins of the Ribosome, argue that ribosome complexity is a molecular fossil that has implied information about ancient biological processes, which allows for a reconstruction of how the proteins and RNA coevolved—as the ribosome became a ribozyme(28) possessing the exquisite specific activity of peptide synthesis. One might surmise that the earliest ribozymes would have been crude constructs possessing not-so specific activities, molecules with rather promiscuous activities, catalyzing a range of reactions. However, Chen et al. examine the evidence and discuss the Promiscuous Ribozymes and Their Proposed Role in Prebiotic Evolution. Their review suggests that the de novo ribozymes are not more promiscuous than their evolved counterparts pointing to the advantage of being promiscuous under selective pressures for prebiotic chemical evolution. In the final article, Maurel and associates consider the function of ribozymes under high pressure, examining the structure–function relationship of the self-cleaving hairpin and hammerhead ribozymes. What they describe in Ribozyme Chemistry: To Be or Not To Be under High Pressure suggests that such activities of these ribozymes are slowed down by increase in pressure. They examine plausible mechanisms to account for this behavior, which they discuss in the context of the extreme conditions that can occur in deep-sea vents or hydrothermal surfaces. Through the various articles in this thematic issue on Chemical Evolution and the Origins of Life we hope the reader will see how this collective scientific endeavor is making meaningful progress on multiple fronts and offering plausible alternative solutions to long-standing problems for which once attractive and popular solutions have not held up to experimental scrutiny. The intent of this special issue is not to make the claims that specific problems have been solved, but to highlight the progress made so far and to emphasize that there are still problems that are (and may be) unsolved.(29) This special issue should be construed as an open invitation and a call for more chemists to get involved in this fascinating and enigmatic journey(30)—of developing a systematic understanding of the origins of life from a chemical perspective: the chemical-beginning, chemical-evolution, and chemical-life. Views expressed in this editorial are those of the authors and not necessarily the views of the ACS. This article references 30 other publications.

中文翻译：

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简介：化学进化与生命起源。

本文是 化学演化与生命起源 特刊。 Ramanarayanan Krishnamurthy出生于印度金奈。他获得了理学学士学位。毕业于维韦卡南达学院（马德拉斯大学）和理学硕士。来自孟买的印度理工学院（IIT）。他获得了博士学位。在David Hart的指导下从俄亥俄州立大学（OSU）获得。他曾与Eschenmoser一起在苏黎世瑞士联邦理工学院（ETH）担任博士后研究员，并与斯克里普斯海洋研究所的Gustaf Arrhenius成为NASA-NSCORT研究员。然后，他重新加入了位于加州拉荷亚斯克里普斯研究所的斯卡格斯化学生物学研究所的Eschenmoser，建立了长达13年的合作伙伴关系。他目前是斯克里普斯研究所（Scripps Research Institute）化学副教授。他是NSF / NASA化学进化中心（CCE）的科学合作伙伴，也是西蒙斯生命起源合作组织（SCOL）的成员，并被任命为益生元化学和早期地球环境（PCE3）的联席负责人财团，是NASA天文生物学计划中的五个研究协调网络之一。克里希纳穆尔蒂教授当选为国际社会的生活在2011年起源的研究的研究员。尼古拉斯·哈德（Nicholas Hud）出生于加利福尼亚州的洛杉矶。他拥有Loyola Marymount大学的学士学位。他的博士学位 由加州大学戴维斯分校授予Rod Balhorn教授实验室中鱼精蛋白对DNA缩合的物理研究。他曾与加州大学洛杉矶分校的生物物理学博士后研究员Juli Feigon和Frank Anet在一起。他于1999年加入佐治亚理工大学化学与生物化学学院，并于2016年被任命为Regents教授。他目前担任NSF / NASA化学演化中心（CCE）的主任，以及Parker的副主任。 H. Petit生物工程与生物科学研究所。教授 铁汉被选为2019年美国科学促进会院士和国际社会的生活在2014年起源的研究的研究员，是一个希格玛西在2015 - 2017年杰出讲师。化学进化和生命起源是一个跨越并超越许多领域的主题：科学，时代，文化乃至太空的所有学科。（1,2）这一主题持久地吸引着科学家和公众的想象力（3-5）理解生命如何在地球和其他地方出现是一项历史性和重建性的努力，但它在很大程度上也是当代的并且不断刷新的科学事业。（6）这些努力有着悠久的历史并且受到了推动通过竞争蛋白质，RNA，新陈代谢，（7-12）从化学家的角度出发，这一追求的重点是了解在非生物地球化学约束下，积聚在年轻星球上的元素和分子如何发生转变。 —成为具有新兴模式和行为的自组装，自我维持的互动系统，并开始演变为可以被视为生命的实体。（13）从天化学，益生元化学和生物化学的角度来看，该主题涉及我们目前对与生命的化学起源相关的一系列主题的理解。加上他们令人赞叹的进步，每个贡献也都承认我们渴望解决一个大问题“可以通过实验证明或理解生命的起源吗？”时仍要解决的悬而未决的问题和挑战。虽然不可能在历史上准确的背景下回答该问题，但确实是在化学家的掌握范围内（在天化学，观测到的早期地球及其大气的地质约束，益生元有机化学和现存的生物化学的指导下）实验室通过化学反应将分子转化为近似于生物学中观察到的行为/现象的系统。（14）尽管这可能不足以“在试管中重现生命”，当然，对于可能导致生命起源的化学过程的出现和发展，这将是一个更为适度但仍然有力的证据。此主题问题始于Sandford及其同事描述了益生元的天化学和星际云和原星盘中天体生物学分子的形成行星系统形成的地方，从而为可用于导致行星生命起源的过程中可用的化学物种奠定了基础。如果这个过程确实是“普遍的”，那么就会对宇宙中其他地方的地球外生命的可能性提出疑问，Sandford及其同事认为，在当地条件有利于这些化学过程的地方，生命可能很普遍。地球是我们目前唯一拥有生命的星球，可以指引我们在其他地方寻找生命，因此我们必须对生物学及其过程的本质和独特性有一定的了解，才能为生命探测任务制定一套标准。（15）地球上生物学的奇异性是同质性，包括使用l-氨基酸和d-单手制糖。（16）但是，使用手性不对称性作为确定的生物特征会因可能干扰的非生物过程而变得复杂。Glavin等。审查了在陨石中发现的分子的对映体和同位素组成及分布，并提出了一系列关于寻找手性不对称性作为我们太阳系中潜在生物签名的标准。这些作者还提出了“样品返回任务”的论点，这可能代表了我们最好的机会来牢固地确定手性不对称性的起源，将其作为太阳系其他生物的潜在生物特征。一旦沉积了源分子，例如氨基酸，核碱基和糖结构单元（或原位形成））在早期行星（例如地球）上，它们之间导致更复杂分子的相互作用和反应被认为是在地球化学约束下自然过程的一部分。（17）例如，磷酸化是地球化学中的中心反应。生物学中的新陈代谢，结构和复制过程也被广泛认为在推动化学进化朝地球早期生命的发展中发挥了重要作用。（18）正如Pasek所指出的，益生元磷酸化的热力学可用于评估各种来源，过程和地球化学环境的可能性，这些环境能够将无机磷化合物转化为有机磷酸盐以进行进一步处理。氨基酸是地球早期的益生元似化合物，是肽和蛋白质的组成部分，是现存生物学的催化引擎。（19）在编码蛋白酶出现之前，益生元肽的非共价相互作用可能发挥了作用。在新兴的互连分子网络中发挥关键作用。Ashkenasy，Leman及其同事总结了氨基酸（和共存分子）如何转化为肽和原肽的机制，并讨论了益生元肽在生命起源中作为分子中心的早期作用。此外，他们回顾了益生元肽（和前肽）与其他类别分子的可能的相互作用，从而强调了化学进化中协同相互作用的系统化学方法（20）。生命中另一类至关重要的分子是核苷酸，即RNA和DNA的单体，与氨基酸相比，其益生元的可用性更具挑战性。（21）然而，RNA在现存生物学中，尤其是肽中的核糖体中起着核心作用。合成，已经迫使人们对地球早期的RNA世界场景进行了推算。（22）这种强大的推动力导致人们为建立合理的标准核苷酸的益生元合成做出了巨大的努力。Krishnamurthy及其同事回顾了非生物核苷酸合成化学的现状在益生元的背景下，指出在阐明地球早期地球化学背景下普遍认为是益生元的RNA和DNA组成部分的途径方面仍面临的挑战。在产生标准糖（核糖）和核苷碱基（A，U，G和C）的许多反应中形成的大量非规范产物引发了一个问题：是化学进化和起源中涉及的替代核苷和核苷酸吗？ （23）Hud等人。在他们的评论中指出，非规范性核苷酸和核苷酸的益生元合成，类似的或竞争的化学物质会形成替代的核碱基，糖，骨架连接子和核苷/核苷酸。除了RNA的四个规范核苷酸以外，这些替代构件有可能产生自组装/功能性替代原始RNA或前RNA候选物，在化学进化过程中需要认真考虑和评估其作用（24,25）在以上所有情况中，必须考虑结构单元的手性，尤其是当其走向聚合物和超分子组装时。单手性或单手性在生物学中如何表现为d-糖和l氨基酸是一种极其重要的现象，但尚不为人所知。（26）布莱克蒙德通过考虑同手性来源的自催化模型解决了这个问题。并深入探讨了Soai反应（扩增自催化反应的唯一已知例子）作为模型，以研究益生元似的变体是否可行。越来越多地，同手性的出现不是由单个事件决定的，而是由一系列协同和持续的化学和物理过程决定的。尽管历史细节仍然不清楚，但从某种程度上讲，无论是化学还是生物学方法，进化过程都已经弄清了制造核酶所需的所有条件，即核糖体所代表的RNA编码的催化分子，核糖体负责所有生物的编码蛋白质合成（27）威廉姆斯和他的同事在他们的综述中，“树的根：核糖体的重要性，进化和起源”，有人说核糖体的复杂性是一种分子化石，它隐含了有关古代生物学过程的信息，从而可以重建蛋白质和RNA的相互作用方式，因为核糖体变成了具有精细肽合成特异性活性的核酶（28）。一个人可能会推测，最早的核酶应该是具有不那么特异活性的粗结构，这些分子具有相当混杂的活性，能够催化一系列反应。然而，Chen等。检查证据并讨论混杂核酶及其在益生元进化中的作用。他们的评论表明，从头开始核酶并不比它们进化的同伴更混杂，指出在益生元化学进化的选择性压力下混杂的优势。在最后一篇文章中，Maurel及其同事考虑了高压下核酶的功能，研究了自解离发夹和锤头状核酶的结构与功能关系。他们在“核酶化学：要承受高压或不承受高压”中描述的内容表明，这些核酶的这种活性会因压力升高而减慢。他们研究了可能的机制来解释这种行为，并在深海喷口或热液表面可能发生的极端条件下对此进行了讨论。通过本专题中的各种文章，化学进化与生命的起源我们希望读者能看到这种集体的科学努力如何在多个方面取得有意义的进展，并为长期存在的问题提供可行的替代解决方案，而长期存在的问题曾经没有受到实验性审查的关注。这个特殊问题的目的不是要声称已经解决了特定的问题，而是要强调到目前为止所取得的进展，并强调仍然存在（并且可能）尚未解决的问题。（29）这个特殊问题应被解释为公开邀请，并呼吁更多的化学家参与这一迷人而神秘的旅程（30），以从化学的角度对生命起源进行系统的理解：化学-开始，化学演化和化学寿命。本社论中表达的观点只是作者的观点，不一定是ACS的观点。本文引用了其他30种出版物。