9:00 AM - 9:30 AM
[U12-01] Chemical evolution to functional biopolymers on early Earth and early Mars
★Invited Papers
Keywords:chemical evolution, borate, ribose
Life’s functional biopolymers (i.e., DNA/RNA and proteins) comprise sugars, nucleobases, and amino acids. They are regarded as essential biomolecules for chemical evolution to the origin of life. These biomolecules were provided to the prebiotic Earth by meteorites. In chemistry, these molecules could be formed from simple molecules such as formaldehyde, ammonia, and hydrogen cyanide. However, it remains unclear which ancient geological settings facilitated the formation of the essential biomolecules and how they could evolve into functional biopolymers. This talk introduces the recent results of our studies on the formation of biomolecules and their possible chemical evolution to oligonucleotides and polypeptides.
Incubation of formaldehyde with small amounts of glycolaldehyde that could be formed from CO2/CO and H2O yields sugars, including ribose, even in neutral to slightly acidic solutions simulating ancient open oceans (Ono et al., 2024). In alkaline aqueous environments, ribose can form rapidly and more efficiently from formaldehyde by simple heating, but successive reactions under the same conditions subsequently consume ribose. This could be managed by borate that stabilizes ribose by forming a complex. Ribose could be converted into ribose 5-phosphate by dehydrating solutions containing ribose with soluble phosphate and even with hydroxyapatite when carbonate was available (Hirakawa et al., 2022; Takabayashi et al., 2023). The yields were improved with borate that could stabilize ribose. We recently found that ribose 5-phosphate can oligomerize by dehydrating the solutions more efficiently than nucleotide oligomerization. Abundant cyanide than formaldehyde needs to form nucleobases (Callahan and Cleaves, 2023), but in the opposite case, canonical nucleobase was difficult to form (Hirakawa et al., 2025). Alternatively, nucleobases could be provided by meteorites and meteorite impacts (Furukawa et al., 2015; Oba et al., 2022). If terrestrial or extraterrestrial nucleobases can react with polymers of Ribose 5-phosphate, this could be a new and more plausible pathway for forming prebiotic RNA. Borate also catalyzes the formation of polypeptides (Sumie et al., 2023). Boron could be extracted from TTG-like proto-crust by hydrothermal activities and discharged around the land area, as suggested by δ11B isotopes of tourmaline in 3.8 Ga rocks (Grew et al., 2015; Furukawa and Kakegawa, 2017). Thus, these experimental works suggest that the prebiotic evaporative basins around proto-continents were an oasis for functional biopolymers that could potentially contribute to the origin of life.
The early Martian atmosphere might have provided more formaldehyde due to its relatively reduced conditions (Koyama et al., 2024; Ueno et al., 2024). Thus, parts of the formaldehyde chemistry (i.e., sugar synthesis) might have been driven even on early Mars. Synthesizing amino acids and nucleobases needs abundant ammonia and cyanides. Thus, the availability of these molecules might be a constraint for chemical evolution on early Mars. Meteorites could provide amino acids and nucleobases on early Mars. Boron was found in a Martian meteorite, and evaporative environments were abundant on early Mars. Thus, a part of the chemical evolution discussed for prebiotic Earth could have progressed on early Mars. Further geological evidence and investigations on the Martian atmosphere will allow a more reasonable comparison of chemical evolution between the two planets.
Incubation of formaldehyde with small amounts of glycolaldehyde that could be formed from CO2/CO and H2O yields sugars, including ribose, even in neutral to slightly acidic solutions simulating ancient open oceans (Ono et al., 2024). In alkaline aqueous environments, ribose can form rapidly and more efficiently from formaldehyde by simple heating, but successive reactions under the same conditions subsequently consume ribose. This could be managed by borate that stabilizes ribose by forming a complex. Ribose could be converted into ribose 5-phosphate by dehydrating solutions containing ribose with soluble phosphate and even with hydroxyapatite when carbonate was available (Hirakawa et al., 2022; Takabayashi et al., 2023). The yields were improved with borate that could stabilize ribose. We recently found that ribose 5-phosphate can oligomerize by dehydrating the solutions more efficiently than nucleotide oligomerization. Abundant cyanide than formaldehyde needs to form nucleobases (Callahan and Cleaves, 2023), but in the opposite case, canonical nucleobase was difficult to form (Hirakawa et al., 2025). Alternatively, nucleobases could be provided by meteorites and meteorite impacts (Furukawa et al., 2015; Oba et al., 2022). If terrestrial or extraterrestrial nucleobases can react with polymers of Ribose 5-phosphate, this could be a new and more plausible pathway for forming prebiotic RNA. Borate also catalyzes the formation of polypeptides (Sumie et al., 2023). Boron could be extracted from TTG-like proto-crust by hydrothermal activities and discharged around the land area, as suggested by δ11B isotopes of tourmaline in 3.8 Ga rocks (Grew et al., 2015; Furukawa and Kakegawa, 2017). Thus, these experimental works suggest that the prebiotic evaporative basins around proto-continents were an oasis for functional biopolymers that could potentially contribute to the origin of life.
The early Martian atmosphere might have provided more formaldehyde due to its relatively reduced conditions (Koyama et al., 2024; Ueno et al., 2024). Thus, parts of the formaldehyde chemistry (i.e., sugar synthesis) might have been driven even on early Mars. Synthesizing amino acids and nucleobases needs abundant ammonia and cyanides. Thus, the availability of these molecules might be a constraint for chemical evolution on early Mars. Meteorites could provide amino acids and nucleobases on early Mars. Boron was found in a Martian meteorite, and evaporative environments were abundant on early Mars. Thus, a part of the chemical evolution discussed for prebiotic Earth could have progressed on early Mars. Further geological evidence and investigations on the Martian atmosphere will allow a more reasonable comparison of chemical evolution between the two planets.