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364 KiB

Open AccessArticle

Simulations of Prebiotic Chemistry under Post-Impact Conditions on Titan

by Carol Turse, Johannes Leitner, Maria Firneis and Dirk Schulze-Makuch

Life 2013, 3(4), 538-549; https://doi.org/10.3390/life3040538 - 17 Dec 2013

Cited by 5 | Viewed by 8365

The problem of how life began can be considered as a matter of basic chemistry. How did the molecules of life arise from non-biological chemistry? Stanley Miller’s famous experiment in 1953, in which he produced amino acids under simulated early Earth conditions, was [...] Read more.

The problem of how life began can be considered as a matter of basic chemistry. How did the molecules of life arise from non-biological chemistry? Stanley Miller’s famous experiment in 1953, in which he produced amino acids under simulated early Earth conditions, was a huge leap forward in our understanding of this problem. Our research first simulated early Earth conditions based on Miller’s experiment and we then repeated the experiment using Titan post-impact conditions. We simulated conditions that could have existed on Titan after an asteroid strike. Specifically, we simulated conditions after a potential strike in the subpolar regions of Titan that exhibit vast methane-ethane lakes. If the asteroid or comet was of sufficient size, it would also puncture the icy crust and bring up some of the subsurface liquid ammonia-water mixture. Since, O’Brian, Lorenz and Lunine showed that a liquid water-ammonia body could exist between about 10²–10⁴ years on Titan after an asteroid impact we modified our experimental conditions to include an ammonia-water mixture in the reaction medium. Here we report on the resulting amino acids found using the Titan post-impact conditions in a classical Miller experimental reaction set-up and how they differ from the simulated early Earth conditions. Full article

(This article belongs to the Special Issue Prebiotic Chemistry: Chemical Evolution of Organics on the Primitive Earth)

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428 KiB

Open AccessArticle

Natural Pyrrhotite as a Catalyst in Prebiotic Chemical Evolution

by Alejandra López Ibáñez De Aldecoa, Francisco Velasco Roldán and César Menor-Salván

Life 2013, 3(3), 502-517; https://doi.org/10.3390/life3030502 - 28 Aug 2013

Cited by 9 | Viewed by 11082

Abstract

The idea of an autotrophic organism as the first living being on Earth leads to the hypothesis of a protometabolic, complex chemical system. In one of the main hypotheses, the first metabolic systems emerged from the interaction between sulfide minerals and/or soluble iron-sulfide [...] Read more.

The idea of an autotrophic organism as the first living being on Earth leads to the hypothesis of a protometabolic, complex chemical system. In one of the main hypotheses, the first metabolic systems emerged from the interaction between sulfide minerals and/or soluble iron-sulfide complexes and fluids rich in inorganic precursors, which are reduced and derived from crustal or mantle activity. Within this context, the possible catalytic role of pyrrhotite, one of the most abundant sulfide minerals, in biomimetic redox and carbon fixation reactions was studied. Our results showed that pyrrhotite, under simulated hydrothermal conditions, could catalyze the pyruvate synthesis from lactate and that a dynamic system formed by coupling iron metal and iron-sulfur species in an electrochemical cell could promote carbon fixation from thioacetate esters. Full article

(This article belongs to the Special Issue Prebiotic Chemistry: Chemical Evolution of Organics on the Primitive Earth)

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642 KiB

Open AccessArticle

A Necessary Condition for Coexistence of Autocatalytic Replicators in a Prebiotic Environment

by Andres F. Hernandez and Martha A. Grover

Life 2013, 3(3), 403-420; https://doi.org/10.3390/life3030403 - 24 Jul 2013

Cited by 2 | Viewed by 5885

Abstract

A necessary, but not sufficient, mathematical condition for the coexistence of short replicating species is presented here. The mathematical condition is obtained for a prebiotic environment, simulated as a fed-batch reactor, which combines monomer recycling, variable reaction order and a fixed monomer inlet [...] Read more.

A necessary, but not sufficient, mathematical condition for the coexistence of short replicating species is presented here. The mathematical condition is obtained for a prebiotic environment, simulated as a fed-batch reactor, which combines monomer recycling, variable reaction order and a fixed monomer inlet flow with two replicator types and two monomer types. An extensive exploration of the parameter space in the model validates the robustness and efficiency of the mathematical condition, with nearly 1.7% of parameter sets meeting the condition and half of those exhibiting sustained coexistence. The results show that it is possible to generate a condition of coexistence, where two replicators sustain a linear growth simultaneously for a wide variety of chemistries, under an appropriate environment. The presence of multiple monomer types is critical to sustaining the coexistence of multiple replicator types. Full article

(This article belongs to the Special Issue Prebiotic Chemistry: Chemical Evolution of Organics on the Primitive Earth)

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906 KiB

Open AccessArticle

Phosphate Activation via Reduced Oxidation State Phosphorus (P). Mild Routes to Condensed-P Energy Currency Molecules

by Terence P. Kee, David E. Bryant, Barry Herschy, Katie E. R. Marriott, Nichola E. Cosgrove, Matthew A. Pasek, Zachary D. Atlas and Claire R. Cousins

Life 2013, 3(3), 386-402; https://doi.org/10.3390/life3030386 - 19 Jul 2013

Cited by 30 | Viewed by 9023

Abstract

The emergence of mechanisms for phosphorylating organic and inorganic molecules is a key step en route to the earliest living systems. At the heart of all contemporary biochemical systems reside reactive phosphorus (P) molecules (such as adenosine triphosphate, ATP) as energy currency molecules [...] Read more.

The emergence of mechanisms for phosphorylating organic and inorganic molecules is a key step en route to the earliest living systems. At the heart of all contemporary biochemical systems reside reactive phosphorus (P) molecules (such as adenosine triphosphate, ATP) as energy currency molecules to drive endergonic metabolic processes and it has been proposed that a predecessor of such molecules could have been pyrophosphate [P₂O₇⁴⁻; PPi(V)]. Arguably the most geologically plausible route to PPi(V) is dehydration of orthophosphate, Pi(V), normally a highly endergonic process in the absence of mechanisms for activating Pi(V). One possible solution to this problem recognizes the presence of reactive-P containing mineral phases, such as schreibersite [(Fe,Ni)₃P] within meteorites whose abundance on the early Earth would likely have been significant during a putative Hadean-Archean heavy bombardment. Here, we propose that the reduced oxidation state P-oxyacid, H-phosphite [HPO₃²⁻; Pi(III)] could have activated Pi(V) towards condensation via the intermediacy of the condensed oxyacid pyrophosphite [H₂P₂O₅²⁻; PPi(III)]. We provide geologically plausible provenance for PPi(III) along with evidence of its ability to activate Pi(V) towards PPi(V) formation under mild conditions (80 °C) in water. Full article

(This article belongs to the Special Issue Prebiotic Chemistry: Chemical Evolution of Organics on the Primitive Earth)

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720 KiB

Open AccessArticle

Prebiotic Chemistry: Geochemical Context and Reaction Screening

by Henderson James Cleaves II

Life 2013, 3(2), 331-345; https://doi.org/10.3390/life3020331 - 29 Apr 2013

Cited by 41 | Viewed by 11896

Abstract

The origin of life on Earth is widely believed to have required the reactions of organic compounds and their self- and/or environmental organization. What those compounds were remains open to debate, as do the environment in and process or processes by which they [...] Read more.

The origin of life on Earth is widely believed to have required the reactions of organic compounds and their self- and/or environmental organization. What those compounds were remains open to debate, as do the environment in and process or processes by which they became organized. Prebiotic chemistry is the systematic organized study of these phenomena. It is difficult to study poorly defined phenomena, and research has focused on producing compounds and structures familiar to contemporary biochemistry, which may or may not have been crucial for the origin of life. Given our ignorance, it may be instructive to explore the extreme regions of known and future investigations of prebiotic chemistry, where reactions fail, that will relate them to or exclude them from plausible environments where they could occur. Come critical parameters which most deserve investigation are discussed. Full article

(This article belongs to the Special Issue Prebiotic Chemistry: Chemical Evolution of Organics on the Primitive Earth)

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184 KiB

Open AccessArticle

Is Struvite a Prebiotic Mineral?

by Maheen Gull and Matthew A. Pasek

Life 2013, 3(2), 321-330; https://doi.org/10.3390/life3020321 - 29 Apr 2013

Cited by 23 | Viewed by 9482

Abstract

The prebiotic relevance of mineral struvite, MgNH₄PO₄·6H₂O, was studied experimentally as a phosphorylating reagent and, theoretically, to understand the geochemical requirements for its formation. The effectiveness of phosphorylation by the phosphate mineral, monetite, CaHPO_4, was also [...] Read more.

The prebiotic relevance of mineral struvite, MgNH₄PO₄·6H₂O, was studied experimentally as a phosphorylating reagent and, theoretically, to understand the geochemical requirements for its formation. The effectiveness of phosphorylation by the phosphate mineral, monetite, CaHPO_4, was also studied to compare to the efficiency of struvite. The experiments focused on the phosphorylation reactions of the minerals with organic compounds, such as nucleosides, glycerol and choline chloride, and heat at 75 °C for about 7–8 days and showed up to 28% phosphorylation of glycerol. In contrast, the compositional requirements for the precipitation of struvite are high ammonium and phosphate concentrations, as well as a little Ca²⁺ dissolved in the water. Combined, these requirements suggest that it is not likely that struvite was present in excess on the early Earth to carry out phosphorylation reactions. The present study focuses on the thermodynamic aspects of struvite formation, complementing the results given by Orgel and Handschuh (1973), which were based on the kinetic effects. Full article

(This article belongs to the Special Issue Prebiotic Chemistry: Chemical Evolution of Organics on the Primitive Earth)

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Review

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295 KiB

Open AccessReview

Formaldehyde—A Key Monad of the Biomolecular System

by Christian R. Noe, Jerome Freissmuth, Peter Richter, Christian Miculka, Bodo Lachmann and Simon Eppacher

Life 2013, 3(3), 486-501; https://doi.org/10.3390/life3030486 - 16 Aug 2013

Cited by 3 | Viewed by 8868

Abstract

Experiments will be presented and reviewed to support the hypothesis that the intrinsic reactivity of formaldehyde may lead to the formation of a rather comprehensive set of defined biomolecules, including D-glucose, thus fostering concepts of evolution considering the existence of a premetabolic system [...] Read more.

Experiments will be presented and reviewed to support the hypothesis that the intrinsic reactivity of formaldehyde may lead to the formation of a rather comprehensive set of defined biomolecules, including D-glucose, thus fostering concepts of evolution considering the existence of a premetabolic system as a primordial step in the generation of life. Full article

(This article belongs to the Special Issue Prebiotic Chemistry: Chemical Evolution of Organics on the Primitive Earth)

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275 KiB

Open AccessReview

Simple Organics and Biomonomers Identified in HCN Polymers: An Overview

by Marta Ruiz-Bermejo, María-Paz Zorzano and Susana Osuna-Esteban

Life 2013, 3(3), 421-448; https://doi.org/10.3390/life3030421 - 29 Jul 2013

Cited by 48 | Viewed by 11270

Abstract

Hydrogen cyanide (HCN) is a ubiquitous molecule in the Universe. It is a compound that is easily produced in significant yields in prebiotic simulation experiments using a reducing atmosphere. HCN can spontaneously polymerise under a wide set of experimental conditions. It has even [...] Read more.

Hydrogen cyanide (HCN) is a ubiquitous molecule in the Universe. It is a compound that is easily produced in significant yields in prebiotic simulation experiments using a reducing atmosphere. HCN can spontaneously polymerise under a wide set of experimental conditions. It has even been proposed that HCN polymers could be present in objects such as asteroids, moons, planets and, in particular, comets. Moreover, it has been suggested that these polymers could play an important role in the origin of life. In this review, the simple organics and biomonomers that have been detected in HCN polymers, the analytical techniques and procedures that have been used to detect and characterise these molecules and an exhaustive classification of the experimental/environmental conditions that favour the formation of HCN polymers are summarised. Nucleobases, amino acids, carboxylic acids, cofactor derivatives and other compounds have been identified in HCN polymers. The great molecular diversity found in HCN polymers encourages their placement at the central core of a plausible protobiological system. Full article

(This article belongs to the Special Issue Prebiotic Chemistry: Chemical Evolution of Organics on the Primitive Earth)

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