Scientists recreated the reaction by which carbon isotopes got into different organic compounds, challenging the idea that organic compounds, such as amino acids, were formed by isotope-enriched substrates. Their discovery suggests that the building blocks of meteorite life originate from substrates widely available in the early solar system.
Their results were published online in Scientific progress April 28, 2021.
Carbonaceous meteorites contain the building blocks of life, including amino acids, sugars and nucleobases. These meteorites are potential suppliers of these molecules for the prebiotic Earth.
Small organic molecules present in meteorites are usually enriched in a heavy carbon isotope (13VS). However, the most abundant organic matter in meteorites is depleted in 13C. Such a difference has long puzzled scientists. It was thought that the small molecules originated from 13C enriched substances found in the extremely cold outer solar system and / or the solar nebula.
However, a team of researchers from Tohoku University and Hokkaido University presented a new hypothesis. They argue that formose-like reactions, the formation of sugar from formaldehyde, create considerable differences in the 13C concentration between small and large organic molecules.
By recreating the formose-like reaction in the laboratory, the researchers found that the isotopic carbon components of organic meteorites are created by the formose-like reaction even in a hot aqueous solution.
Their findings suggest that organic compounds formed without the use of isotopically enriched substrates from the outer solar system; rather, their formation may have taken place using substrates commonly found in the early solar system.
“The difference in isotopic composition of carbon between small organic compounds and large insoluble organic matter is one of the most mysterious characteristics of organic compounds in meteorites,” said Yoshihiro Furukawa of Tohoku University, lead author of the ‘study. “However, the behavior of 13C in this reaction completely solves the riddle. “
“Even though the compounds were synthesized 4.6 billion years ago, isotopic compositions tell us about the synthetic reaction process,” added coauthor Yoshito Chikaraishi of Hokkaido University.
Going forward, the research group plans to study the impact of the formose-like reaction on the characteristics of nitrogen and carbon isotopes in a number of organic compounds and meteorite carbonates.
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