Was Adenine the First Purine?

Schwartz, Alan W.; Bakker, C. G.

doi:10.1126/science.11538344

Cited by 42 publications

(16 citation statements)

References 12 publications

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“…Experimental results were in agreement with ab initio , with adenine and hypoxanthine as the most abundant products, followed by the bi-substituted photoproducts [ 77 ]. Purines and pyrimidines may also be formed by polymerization of ammonium cyanide solutions at temperatures ranging from −78 °C to +80 °C, which could have happened in the parent body of carbonaceous chondrites [ 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 ]. Thermochemical computational simulations show that Fischer-Tropsch type (FTT) synthesis is likely the dominant source of nucleobases within a meteorite parent body (planetesimal) model, followed by non-catalytic synthesis (under certain chemical conditions) [ 90 ].…”

Section: Inventory Of Meteoritic N -Heterocyclementioning

confidence: 99%

The Nitrogen Heterocycle Content of Meteorites and Their Significance for the Origin of Life

Martins

2018

Life

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Carbonaceous chondrites are very primitive meteorites that are rich in carbon. They contain many soluble organic compounds, including nitrogen heterocycles. These play a crucial role in present-day living organisms as they are components of the genetic material and of the co-factors of enzymes. This review outlines the nitrogen heterocycle content of carbonaceous meteorites. The potential mechanisms of formation of these molecules are also described. Measurements of the compound-specific carbon and hydrogen isotopic compositions are mentioned as a way of establishing the origin of the nitrogen heterocycles detected in meteorites.

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Section: Inventory Of Meteoritic N -Heterocyclementioning

confidence: 99%

The Nitrogen Heterocycle Content of Meteorites and Their Significance for the Origin of Life

Martins

2018

Life

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“…The same research group demonstrated that unhydrolysed oligomerisation mixtures prepared from HCN in the absence of formaldehyde contain adenine-8-carboxamide, a possible precursor of adenine [ 95 ]. However, 8-hydroxymethyladenine is mostly formed in oligomerisation solutions of HCN when formaldehyde is added, rather than adenine-8-carboxamide or adenine itself [ 96 ]. Also in the context of a primitive cold Earth or icy satellites, Miller and co-workers demonstrated the formation of several purines (xanthine, hypoxanthine, adenine, guanine and 2,6-diaminopurine) in oligomerisation processes of HCN at temperatures between −20 and −78 °C [ 66 , 67 ].…”

Section: Nucleic-acid Basesmentioning

confidence: 99%

Simple Organics and Biomonomers Identified in HCN Polymers: An Overview

Ruíz-Bermejo

Zorzano

Osuna‐Esteban

2013

Life

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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.

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“…The reaction of DAMN with urea leads to the formation of guanine and xanthine in yields of 5-10%. Another prebiotic pathway for the formation of the adenine derivative 8-hydroxymethyladenine (HMA) as well as traces of adenine from HCN and formaldehyde, was experimentally demonstrated by Schwartz & Bakker (1989). Finally, it has been demonstrated recently that guanine can be produced from ammonium cyanide polymerisations (Levy et al 1999).…”

Section: N-heterocycles In Meteoritesmentioning

confidence: 99%

Formation and photostability of N-heterocycles in space

Peeters¹,

Botta

Charnley

et al. 2005

A&A

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Abstract. Nitrogen-containing cyclic organic molecules (N-heterocycles) play important roles in terrestrial biology, for example as the nucleobases in genetic material. It has previously been shown that nucleobases are unlikely to form and survive in interstellar and circumstellar environments. Also, they were found to be unstable against ultraviolet (UV) radiation. However, nucleobases were detected in carbonaceous meteorites, suggesting their formation and survival is possible outside the Earth. In this study, the nucleobase precursor pyrimidine and the related N-heterocycles pyridine and s-triazine were tested for UV stability. All three N-heterocycles were found to photolyse rapidly and their stability decreased with an increasing number of nitrogen atoms in the ring. The laboratory results were extrapolated to astronomically relevant environments. In the diffuse interstellar medium (ISM) these N-heterocycles in the gas phase would be destroyed in 10-100 years, while in the Solar System at 1 AU distance from the Sun their lifetime would not extend beyond several hours. The only environment where small N-heterocycles could survive, is in dense clouds. Pyridine and pyrimidine, but not s-triazine, could survive the average lifetime of such a cloud. The regions of circumstellar envelopes where dust attenuates the UV flux, may provide a source for the detection of N-heterocycles. We conclude that these results have important consequences for the detectability of N-heterocycles in astronomical environments.

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Was Adenine the First Purine?

Cited by 42 publications

References 12 publications

The Nitrogen Heterocycle Content of Meteorites and Their Significance for the Origin of Life

The Nitrogen Heterocycle Content of Meteorites and Their Significance for the Origin of Life

Simple Organics and Biomonomers Identified in HCN Polymers: An Overview

Formation and photostability of N-heterocycles in space

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