Research ArticlePLANETARY SCIENCES

Synthesis of 13C-enriched amino acids with 13C-depleted insoluble organic matter in a formose-type reaction in the early solar system

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Science Advances  28 Apr 2021:
Vol. 7, no. 18, eabd3575
DOI: 10.1126/sciadv.abd3575
  • Fig. 1 AFR experiments and their products.

    Simple heating of formaldehyde, glycolaldehyde, and ammonia with calcium hydroxide formed amino acids, amines, carboxylic acids, and synthetic IOM. Photo credit for the scanning electron microscopy (SEM) image: Yoshinari Iwasa, Tohoku University. Photo credit for the synthetic IOM and SOM: Yoshihiro Furukawa, Tohoku University.

  • Fig. 2 Yields and δ13C values.

    (A) Yields of amino acids and synthetic IOM. Yields are shown on the basis of molar amounts of carbon in products and total starting materials. Initial carbon-based formaldehyde (FA) content is 50%, and glycolaldehyde (GA) content is 50%. (B) Value of δ13C for amino acids, synthetic IOM, and bulk SOM. Blue, red, and gray dashed lines indicate initial δ13C values of GA, FA, and average carbon in the starting materials, respectively. The experimental reproducibility of δ13C values in glycine (Gly), alanine (Ala), β-alanine (β-Ala), total SOM, and synthetic IOM are ±1.8, ±3.5, ±6.4, ±0.4, and ± 0.5‰, respectively (1σ, n = 3).

  • Fig. 3 Schematic model of kinetic isotope fractionation in an AFR.

    (A) Isotope fractionation in the laboratory experiment. A, A2, A3, mA, and An represent formaldehyde, glycolaldehyde, glyceraldehyde, many formaldehyde, and soluble large aldehyde molecules, respectively; k1, k2, and k3 represent the rate constants of the respective reaction. The initial δ13C values of A and A2 are shown as the same value in this figure but were different in the experiments. The rate constant of an elemental reaction in the formose reaction (k1) was significantly higher than the rate constants of amino acid formation (k2 and k3). Black dashed arrows represent potential isotope fractionation associated with amino acid formation from aldehydes. For simplification, the initial isotope ratios of A and A2 should be the same. The variables t1 to t3 represent the time of amino acid formation from the corresponding aldehyde. (B) Isotope fractionation in carbonaceous asteroids in the early solar system. (C) Isotope fractionation in ice-dust grains in the early solar system.

  • Fig. 4 Carbon-based yields of carboxylic acids, amino acids, and synthetic IOM in the experimental product of 80°C heating for 90 days.

    A larger signal of formic acid was detected in the gas chromatography–mass spectrometry (GC/MS) analysis, but the yield was unquantified.

Supplementary Materials

  • Supplementary Materials

    Synthesis of 13C-enriched amino acids with 13C-depleted insoluble organic matter in a formose-type reaction in the early solar system

    Yoshihiro Furukawa, Yoshinari Iwasa, Yoshito Chikaraishi

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