Setting the geological scene for the origin of life and continuing open questions about its emergence

Westall, Francès; Brack, Andrè; Fairén, Alberto González; Schulte, Mitchell D.

doi:10.3389/fspas.2022.1095701

Cited by 12 publications

(9 citation statements)

References 316 publications

(439 reference statements)

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“…Our study has important implications for the emergence of precursors of life in the early Hadean period of the Earth. This is consistent with recent studies suggesting that the basic conditions for the emergence of life were met as early as 4.4 billion years ago [ 60 ]. At this time, the Sun was a particularly magnetically active star, producing frequent and energetic superflares that could have been associated with fast CMEs and high-fluence SEP events.…”

Section: Discussionsupporting

confidence: 93%

Formation of Amino Acids and Carboxylic Acids in Weakly Reducing Planetary Atmospheres by Solar Energetic Particles from the Young Sun

Kobayashi

Ise

Aoki

et al. 2023

Life

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Life most likely started during the Hadean Eon; however, the environmental conditions which contributed to the complexity of its chemistry are poorly known. A better understanding of various environmental conditions, including global (heliospheric) and local (atmospheric, surface, and oceanic), along with the internal dynamic conditions of the early Earth, are required to understand the onset of abiogenesis. Herein, we examine the contributions of galactic cosmic rays (GCRs) and solar energetic particles (SEPs) associated with superflares from the young Sun to the formation of amino acids and carboxylic acids in weakly reduced gas mixtures representing the early Earth’s atmosphere. We also compare the products with those introduced by lightning events and solar ultraviolet light (UV). In a series of laboratory experiments, we detected and characterized the formation of amino acids and carboxylic acids via proton irradiation of a mixture of carbon dioxide, methane, nitrogen, and water in various mixing ratios. These experiments show the detection of amino acids after acid hydrolysis when 0.5% (v/v) of initial methane was introduced to the gas mixture. In the set of experiments with spark discharges (simulation of lightning flashes) performed for the same gas mixture, we found that at least 15% methane was required to detect the formation of amino acids, and no amino acids were detected in experiments via UV irradiation, even when 50% methane was used. Carboxylic acids were formed in non-reducing gas mixtures (0% methane) by proton irradiation and spark discharges. Hence, we suggest that GCRs and SEP events from the young Sun represent the most effective energy sources for the prebiotic formation of biologically important organic compounds from weakly reducing atmospheres. Since the energy flux of space weather, which generated frequent SEPs from the young Sun in the first 600 million years after the birth of the solar system, was expected to be much greater than that of GCRs, we conclude that SEP-driven energetic protons are the most promising energy sources for the prebiotic production of bioorganic compounds in the atmosphere of the Hadean Earth.

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Section: Discussionsupporting

confidence: 93%

Formation of Amino Acids and Carboxylic Acids in Weakly Reducing Planetary Atmospheres by Solar Energetic Particles from the Young Sun

Kobayashi

Ise

Aoki

et al. 2023

Life

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“…We assume that life most likely arose in alkaline hydrothermal vents. However, others favor the idea that life started on the edge of terrestrial hot springs, where the initial components (amino acids, lipids, precursors of nucleotides) were formed under oscillating wet-dry conditions using UV light as the energy flux and HCN as the key food stock [27][28][29][30][31][32]37]. However, this hypothesis does not satisfy the four principles outlined above as well as the alkaline hydrothermal vent hypothesis and, in some cases, does not at all.…”

Section: The Application Of Guiding Principlesmentioning

confidence: 99%

“…In part, because these energy sources are destructive of large molecules and because it is hard to see how those energies could have been transferred to the interior of life's cradles. Ultraviolet light has been championed by John Sutherland (1962-) and others [30,37], given that it can be used to energize the synthesis of a number of important precursor biochemicals including purines and pyrimidines [29,31,32,78]. However, a suitable venue with access to ultraviolet light is difficult to imagine.…”

Section: Venue-what Was the Nature Of The Cradles Of Life?mentioning

confidence: 99%

Opinion: The Key Steps in the Origin of Life to the Formation of the Eukaryotic Cell

Brunk,

Marshall

2024

Life

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The path from life’s origin to the emergence of the eukaryotic cell was long and complex, and as such it is rarely treated in one publication. Here, we offer a sketch of this path, recognizing that there are points of disagreement and that many transitions are still shrouded in mystery. We assume life developed within microchambers of an alkaline hydrothermal vent system. Initial simple reactions were built into more sophisticated reflexively autocatalytic food-generated networks (RAFs), laying the foundation for life’s anastomosing metabolism, and eventually for the origin of RNA, which functioned as a genetic repository and as a catalyst (ribozymes). Eventually, protein synthesis developed, leading to life’s biology becoming dominated by enzymes and not ribozymes. Subsequent enzymatic innovation included ATP synthase, which generates ATP, fueled by the proton gradient between the alkaline vent flux and the acidic sea. This gradient was later internalized via the evolution of the electron transport chain, a preadaptation for the subsequent emergence of the vent creatures from their microchamber cradles. Differences between bacteria and archaea suggests cellularization evolved at least twice. Later, the bacterial development of oxidative phosphorylation and the archaeal development of proteins to stabilize its DNA laid the foundation for the merger that led to the formation of eukaryotic cells.

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“…A previous analysis of the insoluble organic matter of this type of meteorite is in qualitative support of the mentioned recent findings. Therefore, it is possible that aggregate-forming alkylsulfonates and sulfates were delivered to the early Earth during the second wave of meteorite bombardment, before any life forms existed. Although SDS was used in our experiments on the catalytic activity of hemin and in the experiments carried out by Alexy et al on the synthesis of 2,3,7,8,12,13,17,18-octaethylporphyrin, it is likely that a micelle-forming alkylsulfonate would also support the reactions in a similar way as SDS.…”

Section: Prebiological Considerationsmentioning

confidence: 99%

Optimization and Enhancement of the Peroxidase-like Activity of Hemin in Aqueous Solutions of Sodium Dodecylsulfate

Cvjetan,

Schuler,

Ishikawa

et al. 2023

ACS Omega

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Iron porphyrins play several important roles in present-day living systems and probably already existed in very early life forms. Hemin (= ferric protoporphyrin IX = ferric heme b), for example, is the prosthetic group at the active site of heme peroxidases, catalyzing the oxidation of a number of different types of reducing substrates after hemin is first oxidized by hydrogen peroxide as the oxidizing substrate of the enzyme. The active site of heme peroxidases consists of a hydrophobic pocket in which hemin is embedded noncovalently and kept in place through coordination of the iron atom to a proximal histidine side chain of the protein. It is this partially hydrophobic local environment of the enzyme which determines the efficiency with which the sequential reactions of the oxidizing and reducing substrates proceed at the active site. Free hemin, which has been separated from the protein moiety of heme peroxidases, is known to aggregate in an aqueous solution and exhibits low catalytic activity. Based on previous reports on the use of surfactant micelles to solubilize free hemin in a nonaggregated state, the peroxidase-like activity of hemin in the presence of sodium dodecyl sulfate (SDS) at concentrations below and above the critical concentration for SDS micelle formation (critical micellization concentration (cmc)) was systematically investigated. In most experiments, 3,3′,5,5′-tetramethylbenzidine (TMB) was applied as a reducing substrate at pH = 7.2. The presence of SDS clearly had a positive effect on the reaction in terms of initial reaction rate and reaction yield, even at concentrations below the cmc. The highest activity correlated with the cmc value, as demonstrated for reactions at three different HEPES concentrations. The 4-(2-hydroxyethyl)-1-piperazineethanesulfonate salt (HEPES) served as a pH buffer substance and also had an accelerating effect on the reaction. At the cmc, the addition of l-histidine (l-His) resulted in a further concentration-dependent increase in the peroxidase-like activity of hemin until a maximal effect was reached at an optimal l-His concentration, probably corresponding to an ideal mono-l-His ligation to hemin. Some of the results obtained can be understood on the basis of molecular dynamics simulations, which indicated the existence of intermolecular interactions between hemin and HEPES and between hemin and SDS. Preliminary experiments with SDS/dodecanol vesicles at pH = 7.2 showed that in the presence of the vesicles, hemin exhibited similar peroxidase-like activity as in the case of SDS micelles. This supports the hypothesis that micelle- or vesicle-associated ferric or ferrous iron porphyrins may have played a role as primitive catalysts in membranous prebiotic compartment systems before cellular life emerged.

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Setting the geological scene for the origin of life and continuing open questions about its emergence

Cited by 12 publications

References 316 publications

Formation of Amino Acids and Carboxylic Acids in Weakly Reducing Planetary Atmospheres by Solar Energetic Particles from the Young Sun

Formation of Amino Acids and Carboxylic Acids in Weakly Reducing Planetary Atmospheres by Solar Energetic Particles from the Young Sun

Opinion: The Key Steps in the Origin of Life to the Formation of the Eukaryotic Cell

Optimization and Enhancement of the Peroxidase-like Activity of Hemin in Aqueous Solutions of Sodium Dodecylsulfate

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