Biochemistry & Organic Chemistry

Prebiotic Vitamin B3 Synthesis In Carbonaceous Planetesimals

By Keith Cowing
Status Report
October 19, 2023
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Prebiotic Vitamin B3 Synthesis In Carbonaceous Planetesimals
Simulated nicotinic acid abundances compared to measured values in carbonaceous chondrites and asteroid (162173) Ryugu. A rock density of 3 g cm−3 , a porosity of 0.2, [56–58] and an ice density of 0.917 g cm−3 completely filling the pores (after all radionuclides have decayed and aqueous activity has ceased) were assumed as the properties of the planetesimal/carbonaceous chondrite hosting the chemical synthesis. The simulations were run at a pressure of 100 bar. From left to right, the plotted bars show the simulated molecular abundance of nicotinic acid (solid black line on the very left) for the whole temperature range of liquid water, as well as the abundances measured in samples of Cb asteroid (162173) Ryugu collected during the Hayabusa2 spacecraft mission, [14] in the CI chondrite Orgeil, [14] several Antarctic CM2 chondrites, [12] the CM2 chondrites Murchison and Murray, and the ungrouped C2 chondrite Tagish Lake [13] as lines and shaded ranges described in the legend. Each time, the measured nicotinic acid abundance and the sum of all isomers (nicotinic acid, isonicotinic acid, picolinic acid) are given, since thermochemical equilibrium simulations cannot distinguish between isomers. The type of extraction method used (hot water, cold water ultrasonication, HCl-hydrolyzed, formic acid) is denoted next to each panel. A tabulated version of the data presented here is available in the Supporting Information in Table S1. — astro-ph.EP

Aqueous chemistry within carbonaceous planetesimals is promising for synthesizing prebiotic organic matter essential to all life.

Meteorites derived from these planetesimals delivered these life building blocks to the early Earth, potentially facilitating the origins of life.

Here, we studied the formation of vitamin B3 as it is an important precursor of the coenzyme NAD(P)(H), which is essential for the metabolism of all life as we know it. We propose a new reaction mechanism based on known experiments in the literature that explains the synthesis of vitamin B3.

It combines the sugar precursors glyceraldehyde or dihydroxyacetone with the amino acids aspartic acid or asparagine in aqueous solution without oxygen or other oxidizing agents. We performed thermochemical equilibrium calculations to test the thermodynamic favorability. The predicted vitamin B3 abundances resulting from this new pathway were compared with measured values in asteroids and meteorites.

We conclude that competition for reactants and decomposition by hydrolysis are necessary to explain the prebiotic content of meteorites. In sum, our model fits well into the complex network of chemical pathways active in this environment.

Klaus Paschek, Mijin Lee, Dmitry A. Semenov, Thomas K. Henning

Comments: Accepted for publication in ChemPlusChem. The authors Klaus Paschek and Mijin Lee contributed equally. 18 pages, 7 figures (all colored). Supporting Information is available at this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Chemical Physics (physics.chem-ph)
Cite as: arXiv:2310.11433 [astro-ph.EP] (or arXiv:2310.11433v1 [astro-ph.EP] for this version)
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Journal reference: ChemPlusChem 2023, e202300508
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Submission history
From: Klaus Paschek
[v1] Tue, 17 Oct 2023 17:42:52 UTC (4,338 KB)
Astrobiology, Astrochemistry

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻