Is there a common chemical model for life in the universe?

Benner, Steven A.; Ricardo, Alonso; Carrigan, Matthew A.

doi:10.1017/cbo9780511730191.016

Cited by 8 publications

(7 citation statements)

References 110 publications

(101 reference statements)

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“…At the center of the problem of bio-origins lies a contrast between observations made routinely in two fields. In chemistry, when free energy is applied to organic matter without Darwinian evolution, the matter devolves to become more and more “asphaltic”, as the atoms in the mixture are rearranged to give ever more molecular species (Figure ). − Even nonchemists know of this observation, perhaps from having left cooking unattended in a kitchen. In the resulting “asphaltization”, what was life comes to display fewer and fewer characteristics of life.…”

Section: The Paradox At the Center Of The Bio-origins Problemmentioning

confidence: 99%

Asphalt, Water, and the Prebiotic Synthesis of Ribose, Ribonucleosides, and RNA

2012

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RNA has been called a "prebiotic chemist's nightmare" because of its combination of large size, carbohydrate building blocks, bonds that are thermodynamically unstable in water, and overall intrinsic instability. However, a discontinuous synthesis model is well-supported by experimental work that might produce RNA from atmospheric CO(2), H(2)O, and N(2). For example, electrical discharge in such atmospheres gives formaldehyde (HCHO) in large amounts and glycolaldehyde (HOCH(2)CHO) in small amounts. When rained into alkaline aquifers generated by serpentinizing rocks, these substances were undoubtedly converted to carbohydrates including ribose. Likewise, atmospherically generated HCN was undoubtedly converted in these aquifers to formamide and ammonium formate, precursors for RNA nucleobases. Finally, high reduction potentials maintained by mantle-derived rocks and minerals would allow phosphite to be present in equilibrium with phosphate, mobilizing otherwise insoluble phosphorus for the prebiotic synthesis of phosphite and phosphate esters after oxidation. So why does the community not view this discontinuous synthesis model as compelling evidence for the RNA-first hypothesis for the origin of life? In part, the model is deficient because no experiments have joined together those steps without human intervention. Further, many steps in the model have problems. Some are successful only if reactive compounds are presented in a specific order in large amounts. Failing controlled addition, the result produces complex mixtures that are inauspicious precursors for biology, a situation described as the "asphalt problem". Many bonds in RNA are thermodynamically unstable with respect to hydrolysis in water, creating a "water problem". Finally, some bonds in RNA appear to be "impossible" to form under any conditions considered plausible for early Earth. To get a community-acceptable "RNA first" model for the origin of life, the discontinuous synthesis model must be developed. In particular, the model must be refined so that it yields oligomeric RNA from CO(2), H(2)O, and N(2) without human intervention. This Account describes our efforts in this direction. Our hypothesis centers on a geological model that synthesizes RNA in a prebiotic intermountain dry valley (not in a marine environment). This valley receives high pH run-off from a watershed rich in serpentinizing olivines and eroding borate minerals. The runoff contains borate-stabilized carbohydrates, formamide, and ammonium formate. As atmospheric CO(2) dissolves in the subaerial aquifer, the pH of the aquifer is lowered. In the desert valley, evaporation of water, a solvent with a nucleophilic "background reactivity", leaves behind formamide, a solvent with an electrophilic "background reactivity". As a result, nucleobases, formylated nucleobases, and formylated carbohydrates, including formylated ribose, can form. Well-known chemistry transforms these structures into nucleosides, nucleotides, and partially formylated oligomeric RNA.

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Section: The Paradox At the Center Of The Bio-origins Problemmentioning

confidence: 99%

Asphalt, Water, and the Prebiotic Synthesis of Ribose, Ribonucleosides, and RNA

2012

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“…According to a dictum of Nobel laureate Professor Vladimir Prelog, natural products constitute the products of billions of years of evolution, and he called upon science to investigate their function . The reconstitution of natural products in the chemical laboratory via total synthesis, their derivatization, and their functional optimization by synthesis (vide infra) are excellent ways of unlocking nature’s secrets enshrined in natural products. − In particular, total synthesis constitutes more than a research field, as synthesis provides a scientific method to investigate problems with exceptional rigor . For both reasons, we have established a total synthesis program to study and to understand the mechanism of action of natural products in biological systems and to evaluate unusual structures, biosyntheses, and powerful biological activities (Scheme ).…”

Section: Copy: Total Synthesismentioning

confidence: 99%

Copy, Edit, and Paste: Natural Product Approaches to Biomaterials and Neuroengineering

Gademann

2015

Acc. Chem. Res.

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Progress in the chemical sciences has formed the world we live in, both on a macroscopic and on a nanoscopic scale. The last century witnessed the development of high performance materials that interact with humans on many layers, from clothing to construction, from media to medical devices. On a molecular level, natural products and their derivatives influence many biological processes, and these compounds have enormously contributed to the health and quality of living of humans. Although coatings of stone materials with oils or resins (containing natural products) have led to improved tools already millennia ago, in contrast today, natural product approaches to designer materials, that is, combining the best of both worlds, remain scarce. In this Account, we will summarize our recent research efforts directed to the generation of natural product functionalized materials, exploiting the strategy of "copy, edit, and paste with natural products". Natural products embody the wisdom of evolution, and only total synthesis is able to unlock the secrets enshrined in their molecular structure. We employ total synthesis ("copy") as a scientific approach to address problems related to molecular structure, the biosynthesis of natural products, and their bioactivity. Additionally, the fundamental desire to investigate the mechanism of action of natural products constitutes a key driver for scientific inquiry. In an emerging area of relevance to society, we have prepared natural products such as militarinone D that can stimulate neurite outgrowth and facilitate nerve regeneration. This knowledge obtained by synthetic organic chemistry on complex natural products can then be used to design structurally simplified compounds that retain the biological power of the parent natural product ("edit"). This process, sometimes referred to as function-oriented synthesis, allows obtaining derivatives with better properties, improving their chemical tractability and reducing the step count of the synthesis. Along these lines, we have demonstrated that militarinone D can be truncated to yield structurally simplified analogs with improved activity. Finally, with the goal of designing bioactive materials, we have immobilized functionally optimized, neuritogenic natural products ("paste"). These materials could facilitate nerve regeneration, act as nerve guidance conduits, or lead to new approaches in neuroengineering. Based on the surface-adhesive properties of electron-deficient catecholates and the knowledge gathered on neuritogenic natural product derivatives, two mechanistically different design principles have been applied to generate neuritogenic materials. In conclusion, natural products, and their functionally optimized analogs, present a large, mostly untapped reservoir of powerful modulators of biological systems, and their hybridization with materials can lead to new approaches in various fields, from biofilm prevention to neuroengineering.

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“…Albeit singularly unlikely, the mere possibility of these processes raises questions regarding the factual limits of biology (10). We here address the likelihood of abiotic formation of cell membranes, one of several assumed prerequisites for the origin of life (11,12), on worlds such as Titan.…”

Section: Introductionmentioning

confidence: 99%

Can polarity-inverted membranes self-assemble on Titan?

Sandström

Rahm

2020

Sci. Adv.

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The environmental and chemical limits of life are two of the most central questions in astrobiology. Our understanding of life’s boundaries has implications on the efficacy of biosignature identification in exoplanet atmospheres and in the solar system. The lipid bilayer membrane is one of the central prerequisites for life as we know it. Previous studies based on molecular dynamics simulations have suggested that polarity-inverted membranes, azotosomes, made up of small nitrogen-containing molecules, are kinetically persistent and may function on cryogenic liquid hydrocarbon worlds, such as Saturn’s moon Titan. We here take the next step and evaluate the thermodynamic viability of azotosome formation. Quantum mechanical calculations predict that azotosomes are not viable candidates for self-assembly akin to lipid bilayers in liquid water. We argue that cell membranes may be unnecessary for hypothetical astrobiology under stringent anhydrous and low-temperature conditions akin to those of Titan.

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Is there a common chemical model for life in the universe?

Cited by 8 publications

References 110 publications

Asphalt, Water, and the Prebiotic Synthesis of Ribose, Ribonucleosides, and RNA

Asphalt, Water, and the Prebiotic Synthesis of Ribose, Ribonucleosides, and RNA

Copy, Edit, and Paste: Natural Product Approaches to Biomaterials and Neuroengineering

Can polarity-inverted membranes self-assemble on Titan?

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