5:15 PM - 6:45 PM
[MIS07-P01] Characterization of macromolecular compounds containing amino acid precursors synthesized in simulated environments of meteorite parent bodies
Keywords:Amino acid, Amino acid precursor
1. Introduction
On the emergence of life, biomolecules such as amino acids, sugars, and nucleobases are necessary. There is an idea that these biomolecules are brought from outside of the earth, since amino acids were found in the Murchison meteorite which fell to Australia in 1969 [1]. These amino acids are considered to be synthesized at interstellar environments and/or inside of meteorite parent bodies. A part of amino acids likely exists as amino acid precursor which can produce amino acid by hydrolysis, and that the amino acid precursor was likely to be synthesized in interstellar environment and inside of meteorite parent bodies [2,3]. The amino acid precursors synthesized in interstellar environment are likely macromolecular materials[4].
Because the characteristics of amino acid precursor synthesized inside of meteorite parent bodies are unknown, in this research, we made an aqueous solution of mixture of formaldehyde, ammonia, and methanol irradiated by gamma rays simulating radioactive decay of 26Al, and then characterized the products containing amino acid precursors.
2. Experimental methods
We prepared composition of starting material as HCHO:NH3:CH3OH:H2O=5:5:1:100, and made it confined in glass tubes in vacuum. Then, these glass tubes were irradiated by gamma rays from 60Co radiation source in Tokyo Institute of Technology (these products are called “FAW”). Then by using size-exclusion chromatography (Shodex OHpak SB-802.5 HQ, 6 μm, 8.0 mm × 300 mm), separation experiment of FAW was conducted. Each separated section was hydrolyzed (6M HCl, 110℃, 24h) and then amino acids were analyzed by using HPLC (NexeraX2) to evaluate the variations of amino acid productions in each section.
3. Results and discussion
Hydantoin, one of candidates of amino acid precursor, was not detected in FAW. In the separation experiment, the amount of amino acid productions from the section which is considered to include aminoacetonitrile was less than other sections. These results suggested that aminoacetonitrile and hydantoin were not major amino acid precursors.
The amount of amino acid production varied by each section, and also the ratio of amino acid production per section varied greatly depending on the type of amino acids. Especially, β-alanine was the most abundantly produced in the section which is considered to include low-molecular compounds unlike other types of amino acids. Therefore, these results indicate that the average molecular weight of amino acid precursors produced in FAW greatly varied among amino acids.
4. Conclusions
In our simulating experiments of amino acid productions in meteorite parent bodies, aminoacetonitrile and hydantoin are not considered as major amino acid precursor. Our results suggested that the average of molecular weight of amino acid precursor greatly varied depending on the type of amino acids.
5. References
[1] Kvenvolden K. A. et al., Proc. Natl. Acad. Sci. U. S. A., 68, 486-490 (1971).
[2] Kebukawa Y. et al., ACS Cent. Sci., 8, 1664-1671 (2022).
[3] Kasamatsu, T. et al., Bull. Chem. Soc. Jpn., 70, 1021-1026 (1997).
[4] Kobayashi, K. et al., Astrobiology: from Simple Molecules to Primitive Life, ed. by V. Basiuk, American Scientific Publishers, Valencia, CA, (2010), pp. 175-186.
On the emergence of life, biomolecules such as amino acids, sugars, and nucleobases are necessary. There is an idea that these biomolecules are brought from outside of the earth, since amino acids were found in the Murchison meteorite which fell to Australia in 1969 [1]. These amino acids are considered to be synthesized at interstellar environments and/or inside of meteorite parent bodies. A part of amino acids likely exists as amino acid precursor which can produce amino acid by hydrolysis, and that the amino acid precursor was likely to be synthesized in interstellar environment and inside of meteorite parent bodies [2,3]. The amino acid precursors synthesized in interstellar environment are likely macromolecular materials[4].
Because the characteristics of amino acid precursor synthesized inside of meteorite parent bodies are unknown, in this research, we made an aqueous solution of mixture of formaldehyde, ammonia, and methanol irradiated by gamma rays simulating radioactive decay of 26Al, and then characterized the products containing amino acid precursors.
2. Experimental methods
We prepared composition of starting material as HCHO:NH3:CH3OH:H2O=5:5:1:100, and made it confined in glass tubes in vacuum. Then, these glass tubes were irradiated by gamma rays from 60Co radiation source in Tokyo Institute of Technology (these products are called “FAW”). Then by using size-exclusion chromatography (Shodex OHpak SB-802.5 HQ, 6 μm, 8.0 mm × 300 mm), separation experiment of FAW was conducted. Each separated section was hydrolyzed (6M HCl, 110℃, 24h) and then amino acids were analyzed by using HPLC (NexeraX2) to evaluate the variations of amino acid productions in each section.
3. Results and discussion
Hydantoin, one of candidates of amino acid precursor, was not detected in FAW. In the separation experiment, the amount of amino acid productions from the section which is considered to include aminoacetonitrile was less than other sections. These results suggested that aminoacetonitrile and hydantoin were not major amino acid precursors.
The amount of amino acid production varied by each section, and also the ratio of amino acid production per section varied greatly depending on the type of amino acids. Especially, β-alanine was the most abundantly produced in the section which is considered to include low-molecular compounds unlike other types of amino acids. Therefore, these results indicate that the average molecular weight of amino acid precursors produced in FAW greatly varied among amino acids.
4. Conclusions
In our simulating experiments of amino acid productions in meteorite parent bodies, aminoacetonitrile and hydantoin are not considered as major amino acid precursor. Our results suggested that the average of molecular weight of amino acid precursor greatly varied depending on the type of amino acids.
5. References
[1] Kvenvolden K. A. et al., Proc. Natl. Acad. Sci. U. S. A., 68, 486-490 (1971).
[2] Kebukawa Y. et al., ACS Cent. Sci., 8, 1664-1671 (2022).
[3] Kasamatsu, T. et al., Bull. Chem. Soc. Jpn., 70, 1021-1026 (1997).
[4] Kobayashi, K. et al., Astrobiology: from Simple Molecules to Primitive Life, ed. by V. Basiuk, American Scientific Publishers, Valencia, CA, (2010), pp. 175-186.