CaCO3 Polymorphs as Mineral Catalysts for Prebiotic Phosphorylation of Uridine. Issue 2 (15th February 2023)

• Record Type: Journal Article
• Authors: Schaible, Micah J.; Castañeda, Alma D.; Menor‐Salvan, Cesar; Pasek, Matthew A.; Burcar, Bradley T.; Orlando, Thomas M.
• Is Part Of: Earth and space science. Volume 10:Issue 2(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-02-15
• Subjects: phosphorylation -- mineral catalysis -- prebiotic -- geochemistry -- astrobiology; Space sciences -- Periodicals; Geophysics -- Periodicals; 500.5
• DOI: 10.1029/2022EA002577
• Languages: English
• ISSNs: 2333-5084

Abstract

Abstract: Establishing plausible routes for the abiotic formation of nucleotides is a challenging problem because the phosphorylation of organic molecules is thermodynamically unfavorable in water, and because common phosphorous‐containing minerals such as apatite are highly insoluble. Reactions of reduced phases such as the meteoritic mineral schreibersite with ammonia containing solutions can form stable amino‐derivatives of phosphates/phosphite, and carbonate‐rich lakes have been suggested as environments where phosphate species and organic molecules could accumulate in significant abundances, thus promoting an ideal environment for abiotic phosphorylation. This work reports the catalytic properties of three CaCO3 polymorphs—calcite, aragonite, and vaterite—on diamidophosphate (DAP)‐induced phosphorylation of the uridine nucleoside during a 24‐hr dry‐down reaction. It is shown that the phosphorylation reaction is accelerated in solutions containing CaCO3 compared to those with no mineral present. For un‐buffered solutions with no mineral present, the primary products formed are uridine monophosphates (UMPs), with yields making up 22.3 ± 3.9% of the total detected species, while solutions containing calcite and aragonite formed primarily UMP dimers (yields of 15.3 ± 1.1% and 14.8 ± 1.3%, respectively). Vaterite showed a strong preference for forming cyclic UMP (cUMP) (26.3 ± 0.3% yield), and no higher order polymers were observed using any carbonate mineral. Reactions containing CaSO4 ·2H2 O (gypsum) showed a preference for forming cUMP, though not as strong as vaterite, while those containing CaCl2 (calcium chloride) and CaWO4 (scheelite) did not yield any phosphorylated products other than UMPs. These results suggest that CaCO3 minerals could have played an important role in facilitating prebiotic phosphorylation in aqueous environments that undergo drying cycles. Plain Language Summary: The abiotic formation of biomolecules containing phosphorous (such as DNA and RNA) on the surface of early Earth faces significant challenges due to the inherent unfavorability of phosphorous‐addition reactions (called phosphorylation) and low expected abundances of available phosphorous species. Carbonate‐rich lakes and pools have been suggested as environments where significant abundances of organic molecules and dissolved phosphorous species could accumulate. This work examines the phosphorylation reaction of the molecule uridine by a prebiotically plausible amidophosphate species—diamidophosphte or DAP—in the presence of three calcium carbonate minerals: calcite, aragonite, and vaterite. The results show that adding uridine and DAP into an aqueous solution of water and minerals and allowing the mixture to dry overnight at 65°C results in for formation of several types of phosphorylated species. While phosphorylated species were detected in all of the experiments, the reactions run with minerals showed a larger abundance of cyclic and dimer species. These results suggest that CaCO3 minerals could have played an important role in facilitating prebiotic phosphorylation in aqueous environments that undergo drying cycles. Key Points: Calcium carbonate minerals produced a catalytic effect on the diamidophosphate (DAP)‐induced phosphorylation of uridine Calcite and aragonite produced predominantly dimer species, while vaterite formed mostly cyclic uridine monophosphate (UMP) The results suggest that an evaporating pool of water containing organics, salts, and reactive phosphorus could form the precursors of RNA