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Michaelian K. The Pigment World: Life's Origins as Photon-Dissipating Pigments. Life (Basel) 2024; 14:912. [PMID: 39063667 PMCID: PMC11277707 DOI: 10.3390/life14070912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2024] [Revised: 07/03/2024] [Accepted: 07/06/2024] [Indexed: 07/28/2024] Open
Abstract
Many of the fundamental molecules of life share extraordinary pigment-like optical properties in the long-wavelength UV-C spectral region. These include strong photon absorption and rapid (sub-pico-second) dissipation of the induced electronic excitation energy into heat through peaked conical intersections. These properties have been attributed to a "natural selection" of molecules resistant to the dangerous UV-C light incident on Earth's surface during the Archean. In contrast, the "thermodynamic dissipation theory for the origin of life" argues that, far from being detrimental, UV-C light was, in fact, the thermodynamic potential driving the dissipative structuring of life at its origin. The optical properties were thus the thermodynamic "design goals" of microscopic dissipative structuring of organic UV-C pigments, today known as the "fundamental molecules of life", from common precursors under this light. This "UV-C Pigment World" evolved towards greater solar photon dissipation through more complex dissipative structuring pathways, eventually producing visible pigments to dissipate less energetic, but higher intensity, visible photons up to wavelengths of the "red edge". The propagation and dispersal of organic pigments, catalyzed by animals, and their coupling with abiotic dissipative processes, such as the water cycle, culminated in the apex photon dissipative structure, today's biosphere.
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Affiliation(s)
- Karo Michaelian
- Department of Nuclear Physics and Application of Radiation, Instituto de Física, Universidad Nacional Autónoma de México, Circuito Interior de la Investigación Científica, Cuidad Universitaria, Cuidad de México CP 04510, Mexico
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2
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Todd ZR, Lozano GG, Kufner CL, Ranjan S, Catling DC, Sasselov DD. UV Transmission in Prebiotic Environments on Early Earth. ASTROBIOLOGY 2024; 24:559-569. [PMID: 38768432 DOI: 10.1089/ast.2023.0077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Ultraviolet (UV) light is likely to have played important roles in surficial origins of life scenarios, potentially as a productive source of energy and molecular activation, as a selective means to remove unwanted side products, or as a destructive mechanism resulting in loss of molecules/biomolecules over time. The transmission of UV light through prebiotic waters depends upon the chemical constituents of such waters, but constraints on this transmission are limited. Here, we experimentally measure the molar decadic extinction coefficients for a number of small molecules used in various prebiotic synthetic schemes. We find that many small feedstock molecules absorb most at short (∼200 nm) wavelengths, with decreasing UV absorption at longer wavelengths. For comparison, we also measured the nucleobase adenine and found that adenine absorbs significantly more than the simpler molecules often invoked in prebiotic synthesis. Our results enable the calculation of UV photon penetration under varying chemical scenarios and allow further constraints on plausibility and self-consistency of such scenarios. While the precise path that prebiotic chemistry took remains elusive, improved understanding of the UV environment in prebiotically plausible waters can help constrain both the chemistry and the environmental conditions that may allow such chemistry to occur.
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Affiliation(s)
- Zoe R Todd
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
- Department of Chemistry, Department of Astronomy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Gabriella G Lozano
- Center for Astrophysics, Harvard and Smithsonian, Cambridge, Massachusetts, USA
| | - Corinna L Kufner
- Center for Astrophysics, Harvard and Smithsonian, Cambridge, Massachusetts, USA
| | - Sukrit Ranjan
- Lunar & Planetary Laboratory/Department of Planetary Sciences, University of Arizona, Tucson, Arizona, USA
| | - David C Catling
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Dimitar D Sasselov
- Center for Astrophysics, Harvard and Smithsonian, Cambridge, Massachusetts, USA
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3
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Harold SE, Warf SL, Shields GC. Prebiotic dimer and trimer peptide formation in gas-phase atmospheric nanoclusters of water. Phys Chem Chem Phys 2023; 25:28517-28532. [PMID: 37847315 DOI: 10.1039/d3cp02915h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Insight into the origin of prebiotic molecules is key to our understanding of how living systems evolved into the complex network of biological processes on Earth. By modelling diglycine and triglycine peptide formation in the prebiotic atmosphere, we provide a plausible pathway for peptide growth. By examining different transition states (TSs), we conclude that the formation of diglycine and triglycine in atmospheric nanoclusters of water in the prebiotic atmosphere kinetically favors peptide growth by an N-to-C synthesis of glycines through a trans conformation. Addition of water stabilizes the TS structures and lowers the Gibbs free activation energies. At temperatures that model the prebiotic atmosphere, the free energies of activation with a six water nanocluster as part of the TS are predicted to be 16 kcal mol-1 relative to the prereactive complex. Examination of the trans vs. cis six water transition states reveals that a homodromic water network that maximizes the acceptor/donor nature of the six waters is responsible for enhanced kinetic favorability of the trans N-to-C pathway. Compared to the non-hydrated trans TS, the trans six-water TS accelerates the reaction of diglycine and glycine to form triglycine by 13 orders of magnitude at 217 K. Nature uses the trans N-to-C pathway to synthesize proteins in the ribosome, and we note the similarities in hydrogen bond stabilization between the transition state for peptide synthesis in the ribosome and the transition states formed in nanoclusters of water in the same pathway. These results support the hypothesis that small oligomers formed in the prebiotic atmosphere and rained onto earth's surface.
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Affiliation(s)
- Shannon E Harold
- Department of Chemistry, Furman University, Greenville, South Carolina 29613, USA.
| | - Skyler L Warf
- Department of Chemistry, Furman University, Greenville, South Carolina 29613, USA.
| | - George C Shields
- Department of Chemistry, Furman University, Greenville, South Carolina 29613, USA.
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Ranjan S, Kufner CL, Lozano GG, Todd ZR, Haseki A, Sasselov DD. UV Transmission in Natural Waters on Prebiotic Earth. ASTROBIOLOGY 2022; 22:242-262. [PMID: 34939825 PMCID: PMC8968845 DOI: 10.1089/ast.2020.2422] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 09/28/2021] [Indexed: 05/10/2023]
Abstract
Ultraviolet (UV) light plays a key role in surficial theories of the origin of life, and numerous studies have focused on constraining the atmospheric transmission of UV radiation on early Earth. However, the UV transmission of the natural waters in which origins-of-life chemistry (prebiotic chemistry) is postulated to have occurred is poorly constrained. In this work, we combine laboratory and literature-derived absorption spectra of potential aqueous-phase prebiotic UV absorbers with literature estimates of their concentrations on early Earth to constrain the prebiotic UV environment in marine and terrestrial natural waters, and we consider the implications for prebiotic chemistry. We find that prebiotic freshwaters were largely transparent in the UV, contrary to assumptions in some models of prebiotic chemistry. Some waters, such as high-salinity waters like carbonate lakes, may be deficient in shortwave (≤220 nm) UV flux. More dramatically, ferrous waters can be strongly UV-shielded, particularly if the Fe2+ forms highly UV-absorbent species such as F e C N 6 4 - . Such waters may be compelling venues for UV-averse origin-of-life scenarios but are unfavorable for some UV-dependent prebiotic chemistries. UV light can trigger photochemistry even if attenuated through photochemical transformations of the absorber (e.g., e a q - production from halide irradiation), which may have both constructive and destructive effects for prebiotic syntheses. Prebiotic chemistries that invoke waters that contain such absorbers must self-consistently account for the chemical effects of these transformations. The speciation and abundance of Fe2+ in natural waters on early Earth is a major uncertainty and should be prioritized for further investigation, as it played a major role in UV transmission in prebiotic natural waters.
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Affiliation(s)
- Sukrit Ranjan
- Department of Earth, Atmospheric & Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Physics and Astronomy, Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University, Evanston, Illinois, USA
- Blue Marble Space Institute of Science, Seattle, Washington, USA
| | - Corinna L. Kufner
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA
| | | | - Zoe R. Todd
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Azra Haseki
- Department of Earth, Atmospheric & Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Harvard College, Cambridge, Massachusetts, USA
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5
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Rimmer PB, Thompson SJ, Xu J, Russell DA, Green NJ, Ritson DJ, Sutherland JD, Queloz DP. Timescales for Prebiotic Photochemistry Under Realistic Surface Ultraviolet Conditions. ASTROBIOLOGY 2021; 21:1099-1120. [PMID: 34152196 PMCID: PMC8570677 DOI: 10.1089/ast.2020.2335] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Ultraviolet (UV) light has long been invoked as a source of energy for prebiotic chemical synthesis, but experimental support does not involve sources of UV light that look like the young Sun. Here we experimentally investigate whether the UV flux available on the surface of early Earth, given a favorable atmosphere, can facilitate a variety of prebiotic chemical syntheses. We construct a solar simulator for the UV light of the faint young Sun on the surface of early Earth, called StarLab. We then attempt a series of reactions testing different aspects of a prebiotic chemical scenario involving hydrogen cyanide (HCN), sulfites, and sulfides under the UV light of StarLab, including hypophosphite oxidation by UV light and hydrogen sulfide, photoreduction of HCN with bisulfite, the photoanomerization of α-thiocytidine, the production of a chemical precursor of a potentially prebiotic activating agent (nitroprusside), the photoreduction of thioanhydrouridine and thioanhydroadenosine, and the oxidation of ethanol (EtOH) by photochemically generated hydroxyl radicals. We compare the output of StarLab to the light of the faint young Sun to constrain the timescales over which these reactions would occur on the surface of early Earth. We predict that hypophosphite oxidation, HCN reduction, and photoproduction of nitroprusside would all operate on the surface of early Earth in a matter of days to weeks. The photoanomerization of α-thiocytidine would take months to complete, and the production of oxidation products from hydroxyl radicals would take years. The photoreduction of thioanhydrouridine with hydrogen sulfide did not succeed even after a long period of irradiation, providing a lower limit on the timescale of several years. The photoreduction of thioanhydroadenosine with bisulfite produced 2'-deoxyriboadenosine (dA) on the timescale of days. This suggests the plausibility of the photoproduction of purine deoxyribonucleotides, such as the photoproduction of simple sugars, proceeds more efficiently in the presence of bisulfite.
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Affiliation(s)
- Paul B. Rimmer
- Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom
- Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
- Address correspondence to: Paul B. Rimmer, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, United Kingdom
| | | | - Jianfeng Xu
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | | | | | | | | | - Didier P. Queloz
- Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
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6
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Green NJ, Xu J, Sutherland JD. Illuminating Life's Origins: UV Photochemistry in Abiotic Synthesis of Biomolecules. J Am Chem Soc 2021; 143:7219-7236. [PMID: 33880920 PMCID: PMC8240947 DOI: 10.1021/jacs.1c01839] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Indexed: 01/15/2023]
Abstract
Solar radiation is the principal source of energy available to Earth and has unmatched potential for the synthesis of organic material from primordial molecular building blocks. As well as providing the energy for photochemical synthesis of (proto)biomolecules of interest in origins of life-related research, light has also been found to often provide remarkable selectivity in these processes, for molecules that function in extant biology and against those that do not. As such, light is heavily implicated as an environmental input on the nascent Earth that was important for the emergence of complex yet selective chemical systems underpinning life. Reactivity and selectivity in photochemical prebiotic synthesis are discussed, as are their implications for origins of life scenarios and their plausibility, and the future directions of this research.
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Affiliation(s)
- Nicholas J. Green
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge
Biomedical Campus, Cambridge CB2 0QH, U.K.
| | - Jianfeng Xu
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge
Biomedical Campus, Cambridge CB2 0QH, U.K.
| | - John D. Sutherland
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge
Biomedical Campus, Cambridge CB2 0QH, U.K.
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7
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Kruse FM, Teichert JS, Trapp O. Prebiotic Nucleoside Synthesis: The Selectivity of Simplicity. Chemistry 2020; 26:14776-14790. [PMID: 32428355 PMCID: PMC7756251 DOI: 10.1002/chem.202001513] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 05/10/2020] [Indexed: 12/29/2022]
Abstract
Ever since the discovery of nucleic acids 150 years ago,[1] major achievements have been made in understanding and decrypting the fascinating scientific questions of the genetic code.[2] However, the most fundamental question about the origin and the evolution of the genetic code remains a mystery. How did nature manage to build up such intriguingly complex molecules able to encode structure and function from simple building blocks? What conditions were required? How could the precursors survive the unhostile environment of early Earth? Over the past decades, promising synthetic concepts were proposed providing clarity in the field of prebiotic nucleic acid research. In this Minireview, we show the current status and various approaches to answer these fascinating questions.
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Affiliation(s)
- Florian M. Kruse
- Department of ChemistryLudwig-Maximilians-University MunichButenandtstr. 5–13'81377MunichGermany
| | - Jennifer S. Teichert
- Department of ChemistryLudwig-Maximilians-University MunichButenandtstr. 5–13'81377MunichGermany
- Max-Planck-Institute for AstronomyKönigstuhl 1769117HeidelbergGermany
| | - Oliver Trapp
- Department of ChemistryLudwig-Maximilians-University MunichButenandtstr. 5–13'81377MunichGermany
- Max-Planck-Institute for AstronomyKönigstuhl 1769117HeidelbergGermany
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8
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Abstract
Delivery of water and organics by asteroid and comet impacts may have influenced prebiotic chemistry on the early Earth. Some recent prebiotic chemistry experiments emphasize hydrogen cyanide (HCN) as a feedstock molecule for the formation of sugars, ribonucleotides, amino acids, and lipid precursors. Here, we assess how much HCN originally contained in a comet would survive impact, using parametric temperature and pressure profiles together with a time-dependent chemistry model. We find that HCN survival mainly depends on whether the impact is hot enough to thermally decompose H2O into reactive radicals, and HCN is therefore rather insensitive to the details of the chemistry. In the most favorable impacts (low impact angle, low velocity, small radius), this temperature threshold is not reached, and intact delivery of HCN is possible. We estimate the global delivery of HCN during a period of Early and Late Heavy Bombardment of the early Earth, as well as local HCN concentrations achieved by individual impacts. In the latter case, comet impacts can provide prebiotically interesting HCN levels for thousands to millions of years, depending on properties of the impactor and of the local environment.
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Affiliation(s)
- Zoe R Todd
- Department of Astronomy, Center for Astrophysics, Harvard and Smithsonian, Cambridge, Massachusetts, USA
| | - Karin I Öberg
- Department of Astronomy, Center for Astrophysics, Harvard and Smithsonian, Cambridge, Massachusetts, USA
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9
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Todd ZR, Fahrenbach AC, Ranjan S, Magnani CJ, Szostak JW, Sasselov DD. Ultraviolet-Driven Deamination of Cytidine Ribonucleotides Under Planetary Conditions. ASTROBIOLOGY 2020; 20:878-888. [PMID: 32267736 PMCID: PMC9634989 DOI: 10.1089/ast.2019.2182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A previously proposed synthesis of pyrimidine ribonucleotides makes use of ultraviolet (UV) light to convert β-d-ribocytidine-2',3'-cyclic phosphate to β-d-ribouridine-2',3'-cyclic phosphate, while simultaneously selectively degrading synthetic byproducts. Past studies of the photochemical reactions of pyrimidines have employed mercury arc lamps, characterized by narrowband emission centered at 254 nm, which is not representative of the UV environment of the early Earth. To further assess this process under more realistic circumstances, we investigated the wavelength dependence of the UV-driven conversion of β-d-ribocytidine-2',3'-cyclic phosphate to β-d-ribouridine-2',3'-cyclic phosphate. We used constraints provided by planetary environments to assess the implications for pyrimidine nucleotides on the early Earth. We found that the wavelengths of light (255-285 nm) that most efficiently drive the deamination of β-d-ribocytidine-2',3'-cyclic phosphate to β-d-ribouridine-2',3'-cyclic phosphate are accessible on planetary surfaces such as those of the Hadean-Archaean Earth for CO2-N2-dominated atmospheres. However, continued irradiation could eventually lead to low levels of ribocytidine in a low-temperature, highly irradiated environment, if production rates are slow.
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Affiliation(s)
- Zoe R. Todd
- Department of Astronomy, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts
- Address correspondence to: Zoe R. Todd, Department of Astronomy, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street Mail-Stop 10, Cambridge, MA 02138
| | | | - Sukrit Ranjan
- SCOL Postdoctoral Fellow, Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Christopher J. Magnani
- Department of Astronomy, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts
| | - Jack W. Szostak
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts
| | - Dimitar D. Sasselov
- Department of Astronomy, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts
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Lin R, Wang Y, Li X, Liu Y, Zhao Y. pH-Dependent Adsorption of Peptides on Montmorillonite for Resisting UV Irradiation. Life (Basel) 2020; 10:life10040045. [PMID: 32325947 PMCID: PMC7235719 DOI: 10.3390/life10040045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 04/14/2020] [Accepted: 04/17/2020] [Indexed: 11/16/2022] Open
Abstract
Ultraviolet (UV) irradiation is considered an energy source for the prebiotic chemical synthesis of life's building blocks. However, it also results in photodegradation of biology-related organic compounds on early Earth. Thus, it is important to find a process to protect these compounds from decomposition by UV irradiation. Herein, pH effects on both the adsorption of peptides on montmorillonite (MMT) and the abilities of peptides to resist UV irradiation due to this adsorption were systematically studied. We found that montmorillonite (MMT) can adsorb peptides effectively under acidic conditions, while MMT-adsorbed peptides can be released under basic conditions. Peptide adsorption is positively correlated with the length of the peptide chains. MMT's adsorption of peptides and MMT-adsorbed peptide desorption are both rapid-equilibrium, and it takes less than 30 min to reach the equilibrium in both cases. Furthermore, compared to free peptides, MMT-adsorbed peptides under acidic conditions are well protected from UV degradation even after prolonged irradiation. These results indicate amino acid/peptides are able to concentrate from aqueous solution by MMT adsorption under low-pH conditions (concentration step). The MMT-adsorbed peptides survive under UV irradiation among other unprotected species (storage step). Then, the MMT-adsorbed peptides can be released to the aqueous solution if the environment becomes more basic (releasing step), and these free peptides are ready for polymerization to polypeptides. Hence, a plausible prebiotic concentration-storage-release cycle of amino acids/peptides for further polypeptide synthesis is established.
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Affiliation(s)
- Rongcan Lin
- Key Laboratory for Chemical Biology of Fujian Province, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; (R.L.); (Y.W.); (X.L.); (Y.Z.)
| | - Yueqiao Wang
- Key Laboratory for Chemical Biology of Fujian Province, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; (R.L.); (Y.W.); (X.L.); (Y.Z.)
| | - Xin Li
- Key Laboratory for Chemical Biology of Fujian Province, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; (R.L.); (Y.W.); (X.L.); (Y.Z.)
| | - Yan Liu
- Key Laboratory for Chemical Biology of Fujian Province, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; (R.L.); (Y.W.); (X.L.); (Y.Z.)
- Correspondence:
| | - Yufen Zhao
- Key Laboratory for Chemical Biology of Fujian Province, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; (R.L.); (Y.W.); (X.L.); (Y.Z.)
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
- Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China
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Sasselov DD, Grotzinger JP, Sutherland JD. The origin of life as a planetary phenomenon. SCIENCE ADVANCES 2020; 6:eaax3419. [PMID: 32076638 PMCID: PMC7002131 DOI: 10.1126/sciadv.aax3419] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 11/22/2019] [Indexed: 05/03/2023]
Abstract
We advocate an integrative approach between laboratory experiments in prebiotic chemistry and geologic, geochemical, and astrophysical observations to help assemble a robust chemical pathway to life that can be reproduced in the laboratory. The cyanosulfidic chemistry scenario described here was developed by such an integrative iterative process. We discuss how it maps onto evolving planetary surface environments on early Earth and Mars and the value of comparative planetary evolution. The results indicate that Mars can offer direct evidence for geochemical conditions similar to prebiotic Earth, whose early record has been erased. The Jezero crater is now the chosen landing site for NASA's Mars 2020 rover, making this an extraordinary opportunity for a breakthrough in understanding life's origins.
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Affiliation(s)
- Dimitar D. Sasselov
- Department of Astronomy, Harvard University, 60 Garden St., Cambridge, MA 02138, USA
- Corresponding author.
| | - John P. Grotzinger
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - John D. Sutherland
- MRC Laboratory of Molecular Biology, Francis Crick Ave., Cambridge CB2 0QH, UK
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12
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Haqq-Misra J. Does the Evolution of Complex Life Depend on the Stellar Spectral Energy Distribution? ASTROBIOLOGY 2019; 19:1292-1299. [PMID: 31429585 DOI: 10.1089/ast.2018.1946] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This article presents the proportional evolutionary time (PET) hypothesis, which posits that the mean time required for the evolution of complex life is a function of stellar mass. The "biological available window" is defined as the region of a stellar spectrum between 200 and 1200 nm that generates free energy for life. Over the ∼4 Gyr history of Earth, the total energy incident at the top of the atmosphere and within the biological available window is ∼1034 J. The hypothesis assumes that the rate of evolution from the origin of life to complex life is proportional to this total energy, which would suggest that planets orbiting other stars should not show signs of complex life if the total energy incident on the planet is below this energy threshold. The PET hypothesis predicts that late K- and M-dwarf stars (M < 0.7 [Formula: see text]) are too young to host any complex life at the present age of the Universe. F-, G-, and early K-dwarf stars (M > 0.7 [Formula: see text]) represent the best targets for the next generation of space telescopes to search for spectroscopic biosignatures indicative of complex life.
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13
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Todd ZR, Szabla R, Szostak JW, Sasselov DD. UV photostability of three 2-aminoazoles with key roles in prebiotic chemistry on the early earth. Chem Commun (Camb) 2019; 55:10388-10391. [PMID: 31380533 PMCID: PMC9631353 DOI: 10.1039/c9cc05265h] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 07/23/2019] [Indexed: 01/20/2023]
Abstract
Three related molecules in the 2-aminoazole family are potentially important for prebiotic chemistry: 2-aminooxazole, 2-aminoimidazole, and 2-aminothiazole, which can provide critical functions as an intermediate in nucleotide synthesis, a nucleotide activating agent, and a selective agent, respectively. Here, we examine the wavelength-dependent photodegradation of these three molecules under mid-range UV light (210-290 nm). We then assess the implications of the observed degradation rates for the proposed prebiotic roles of these compounds. We find that all three 2-aminoazoles degrade under UV light, with half lives ranging from ≈7-100 hours under a solar-like spectrum. 2-Aminooxazole is the least photostable, while 2-aminoimidazole is the most photostable. The relative photostabilities are consistent with the order in which these molecules would be used prebiotically: AO is used first to build nucleotides and AI is used last to activate them.
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Affiliation(s)
- Zoe R. Todd
- Department of Astronomy, Harvard-Smithsonian Center for Astrophysics60 Garden StreetCambridgeMA 02138USA
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital185 Cambridge StreetBostonMA 02114USA
| | - Rafał Szabla
- Institute of Physics, Polish Academy of SciencesAl. Lotników 32/46PL-02668WarsawPoland
| | - Jack W. Szostak
- Howard Hughes Medical Institute, Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital185 Cambridge StreetBostonMA 02114USA
| | - Dimitar D. Sasselov
- Department of Astronomy, Harvard-Smithsonian Center for Astrophysics60 Garden StreetCambridgeMA 02138USA
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14
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Rimmer PB, Xu J, Thompson SJ, Gillen E, Sutherland JD, Queloz D. The origin of RNA precursors on exoplanets. SCIENCE ADVANCES 2018; 4:eaar3302. [PMID: 30083602 PMCID: PMC6070314 DOI: 10.1126/sciadv.aar3302] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 06/19/2018] [Indexed: 05/12/2023]
Abstract
Given that the macromolecular building blocks of life were likely produced photochemically in the presence of ultraviolet (UV) light, we identify some general constraints on which stars produce sufficient UV for this photochemistry. We estimate how much light is needed for the UV photochemistry by experimentally measuring the rate constant for the UV chemistry ("light chemistry", needed for prebiotic synthesis) versus the rate constants for the bimolecular reactions that happen in the absence of the UV light ("dark chemistry"). We make these measurements for representative photochemical reactions involving SO 3 2 - and HS-. By balancing the rates for the light and dark chemistry, we delineate the "abiogenesis zones" around stars of different stellar types based on whether their UV fluxes are sufficient for building up this macromolecular prebiotic inventory. We find that the SO 3 2 - light chemistry is rapid enough to build up the prebiotic inventory for stars hotter than K5 (4400 K). We show how the abiogenesis zone overlaps with the liquid water habitable zone. Stars cooler than K5 may also drive the formation of these building blocks if they are very active. The HS- light chemistry is too slow to work even for early Earth.
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Affiliation(s)
- Paul B. Rimmer
- Cavendish Astrophysics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Jianfeng Xu
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Samantha J. Thompson
- Cavendish Astrophysics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Ed Gillen
- Cavendish Astrophysics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - John D. Sutherland
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Didier Queloz
- Cavendish Astrophysics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
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Xu J, Ritson DJ, Ranjan S, Todd ZR, Sasselov DD, Sutherland JD. Photochemical reductive homologation of hydrogen cyanide using sulfite and ferrocyanide. Chem Commun (Camb) 2018; 54:5566-5569. [PMID: 29761807 PMCID: PMC5972737 DOI: 10.1039/c8cc01499j] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Photoredox cycling during UV irradiation of ferrocyanide ([FeII(CN)6]4-) in the presence of stoichiometric sulfite (SO32-) is shown to be an extremely effective way to drive the reductive homologation of hydrogen cyanide (HCN) to simple sugars and precursors of hydroxy acids and amino acids.
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Affiliation(s)
- Jianfeng Xu
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK.
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16
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Ritson DJ, Battilocchio C, Ley SV, Sutherland JD. Mimicking the surface and prebiotic chemistry of early Earth using flow chemistry. Nat Commun 2018; 9:1821. [PMID: 29739945 PMCID: PMC5940729 DOI: 10.1038/s41467-018-04147-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 04/06/2018] [Indexed: 11/09/2022] Open
Abstract
When considering life's aetiology, the first questions that must be addressed are "how?" and "where?" were ostensibly complex molecules, considered necessary for life's beginning, constructed from simpler, more abundant feedstock molecules on primitive Earth. Previously, we have used multiple clues from the prebiotic synthetic requirements of (proto)biomolecules to pinpoint a set of closely related geochemical scenarios that are suggestive of flow and semi-batch chemistries. We now wish to report a multistep, uninterrupted synthesis of a key heterocycle (2-aminooxazole) en route to activated nucleotides starting from highly plausible, prebiotic feedstock molecules under conditions which mimic this scenario. Further consideration of the scenario has uncovered additional pertinent and novel aspects of prebiotic chemistry, which greatly enhance the efficiency and plausibility of the synthesis.
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Affiliation(s)
- Dougal J Ritson
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK.
| | - Claudio Battilocchio
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.,Syngenta Crop Protection, Process Research, Schaffhauserstrasse 101, CH-4332, Stein, Switzerland
| | - Steven V Ley
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - John D Sutherland
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK.
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