Stability Of Nucleic Acid Bases In Concentrated Sulfuric Acid: Implications For The Habitability Of Venus’ Clouds

By Keith Cowing
Press Release
July 24, 2023
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Stability Of Nucleic Acid Bases In Concentrated Sulfuric Acid: Implications For The Habitability Of Venus’ Clouds
Purine (left) and pyrimidine (right) are stable for two weeks in a range of sulfuric acid concentrations found in the Venus clouds. We have incubated 30-40 mg of each base in 81-98% w/w D2SO4 for two weeks. After the two-week incubation, we measured 1D 13C NMR spectra (solid line spectra), at each of the tested acid concentrations, and compared them to the original 1D 13C NMR spectra collected after ~30-48 h (dashed line spectra and Figure S11). The two-week spectra and the ~30-48 h spectra look virtually identical for all tested concentrations, confirming long-term stability of the compounds in concentrated sulfuric acid solvent. From top to bottom are different concentrations (by weight) of sulfuric acid in water: 98% D2SO4/2% D2O; 94% D2SO4/6% D2O; 88% D2SO4/12% D2O; 81% D2SO4/19% D2O with DMSO-d6 as a reference and at room temperature. All peaks are consistent with the molecules being stable and the structure not being affected by the concentrated sulfuric acid solvent. For two-week stability of other compounds see Figures S12-S14. — astro-ph.EP

What constitutes a habitable planet is a frontier to be explored and requires pushing the boundaries of our terracentric viewpoint for what we deem to be a habitable environment.

Despite Venus’ 700 K surface temperature being too hot for any plausible solvent and most organic covalent chemistry, Venus’ cloud-filled atmosphere layers at 48 to 60 km above the surface hold the main requirements for life: suitable temperatures for covalent bonds; an energy source (sunlight); and a liquid solvent.

Yet, the Venus clouds are widely thought to be incapable of supporting life because the droplets are composed of concentrated liquid sulfuric acid-an aggressive solvent that is assumed to rapidly destroy most biochemicals of life on Earth. Recent work, however, demonstrates that a rich organic chemistry can evolve from simple precursor molecules seeded into concentrated sulfuric acid, a result that is corroborated by domain knowledge in industry that such chemistry leads to complex molecules, including aromatics.

We aim to expand the set of molecules known to be stable in concentrated sulfuric acid. Here, we show that nucleic acid bases adenine, cytosine, guanine, thymine, and uracil, as well as 2,6-diaminopurine and the “core” nucleic acid bases purine and pyrimidine, are stable in sulfuric acid in the Venus cloud temperature and sulfuric acid concentration range, using UV spectroscopy and combinations of 1D and 2D 1H 13C 15N NMR spectroscopy. The stability of nucleic acid bases in concentrated sulfuric acid advances the idea that chemistry to support life may exist in the Venus cloud particle environment.

Sara Seager, Janusz J. Petkowski, Maxwell D. Seager, John H. Grimes Jr., Zachary Zinsli, Heidi R. Vollmer-Snarr, Mohamed K. Abd El-Rahman, David S. Wishart, Brian L. Lee, Vasuk Gautam, Lauren Herrington, William Bains, Charles Darrow

Comments: Final published version available in PNAS this https URL
Subjects: Chemical Physics (physics.chem-ph); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2306.17182 [physics.chem-ph] (or arXiv:2306.17182v1 [physics.chem-ph] for this version)
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Journal reference: PNAS, June 12, 2023, 120 (25) e2220007120
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Submission history
From: Janusz Petkowski
[v1] Mon, 19 Jun 2023 15:49:55 UTC (6,056 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) 🖖🏻