10:45 AM - 12:15 PM
[MIS03-P03] Investigation of amino acid formation simulating hydrothermal process in asteroids: Effects of reaction durations and temperatures
Keywords:Amino acid, asteroids, heat
Introduction
One of the possible scenarios for the origin of life is that biologically relevant organic materials such as amino acids may have been brought from extraterrestrial sources such as meteorites. It is known that organic matter could be formed in asteroids in the early stages of solar system formation through the melting of asteroid ice containing various molecules due to heat from radioactive decay of short-lived radionuclides such as 26Al [1]. In such hydrothermal processes involving liquid water, amino acid precursors could also be formed from HCHO and NH3 aqueous solutions [2]. In this study, we set a wide range of compositions of starting materials and temperature conditions to investigate how the yields of amino acid varies depending on the conditions.
Experimental Methods
Amino acid formation experiments were performed under the conditions shown in B) and C). 200 μL of each sample (i), (ii), and (iii) shown in A) were vacuum-sealed in a glass tube. Samples were acid hydrolyzed with 6 M hydrochloric acid (24h at 110℃), dried, and analyzed for amino acids by ultra-high performance liquid chromatography (Shimadzu NexeraX2) using o-phthalaldehyde and derivatization with 9-fluorenylmethyl chloroformate. Amino acid standard solution samples and each sample were analyzed for quantitative and qualitative analysis.
A. Experimental conditions Composition of starting material
(i)HCHO :NH3 :CH3OH : H2O= 3 : 7 : 0.5 :100, (ii)7 : 3 :1.2 :100, (iii)9 : 1 :1.5 :100
B. Reaction temperature (50℃,150℃,After reacting at 50°C, the temperature was raised to 100°C for further reaction.)
C. Reaction time (1day - 79days)
Results and Discussion
This experiment focused on the production of glycine, the amino acid with the simplest structure. Glycine was produced in greater amounts at higher temperatures for samples of the same composition. In general, the higher the fraction of formaldehyde, the more amino acids were produced, but in the case of (iii), since the fraction of ammonia was too small, the yields of amino acids was small. The yields of amino acids increased in the early stages of the reaction, but after a certain time, the yields of amino acids began to decrease. This trend was more pronounced at higher temperatures. In the sample kept at 50℃, the yields of amino acids started to decrease, and then further decreased when the temperature was increased to 100℃. It was found that the temperature at the initial stage of the reaction, when the amino acid precursors are formed, is important to produce amino acids. In order to produce more amino acids, it would be important to experience a high temperature for a short period of time and then immediately lower the temperature so as not to decrease the amino acids produced.
References
[1] G. D. Cody et al, PNAS 2011, 108, 19171-16. [2] Y. Kebukawa et al, Sci. Adv. 2017, 3, e1602093.
One of the possible scenarios for the origin of life is that biologically relevant organic materials such as amino acids may have been brought from extraterrestrial sources such as meteorites. It is known that organic matter could be formed in asteroids in the early stages of solar system formation through the melting of asteroid ice containing various molecules due to heat from radioactive decay of short-lived radionuclides such as 26Al [1]. In such hydrothermal processes involving liquid water, amino acid precursors could also be formed from HCHO and NH3 aqueous solutions [2]. In this study, we set a wide range of compositions of starting materials and temperature conditions to investigate how the yields of amino acid varies depending on the conditions.
Experimental Methods
Amino acid formation experiments were performed under the conditions shown in B) and C). 200 μL of each sample (i), (ii), and (iii) shown in A) were vacuum-sealed in a glass tube. Samples were acid hydrolyzed with 6 M hydrochloric acid (24h at 110℃), dried, and analyzed for amino acids by ultra-high performance liquid chromatography (Shimadzu NexeraX2) using o-phthalaldehyde and derivatization with 9-fluorenylmethyl chloroformate. Amino acid standard solution samples and each sample were analyzed for quantitative and qualitative analysis.
A. Experimental conditions Composition of starting material
(i)HCHO :NH3 :CH3OH : H2O= 3 : 7 : 0.5 :100, (ii)7 : 3 :1.2 :100, (iii)9 : 1 :1.5 :100
B. Reaction temperature (50℃,150℃,After reacting at 50°C, the temperature was raised to 100°C for further reaction.)
C. Reaction time (1day - 79days)
Results and Discussion
This experiment focused on the production of glycine, the amino acid with the simplest structure. Glycine was produced in greater amounts at higher temperatures for samples of the same composition. In general, the higher the fraction of formaldehyde, the more amino acids were produced, but in the case of (iii), since the fraction of ammonia was too small, the yields of amino acids was small. The yields of amino acids increased in the early stages of the reaction, but after a certain time, the yields of amino acids began to decrease. This trend was more pronounced at higher temperatures. In the sample kept at 50℃, the yields of amino acids started to decrease, and then further decreased when the temperature was increased to 100℃. It was found that the temperature at the initial stage of the reaction, when the amino acid precursors are formed, is important to produce amino acids. In order to produce more amino acids, it would be important to experience a high temperature for a short period of time and then immediately lower the temperature so as not to decrease the amino acids produced.
References
[1] G. D. Cody et al, PNAS 2011, 108, 19171-16. [2] Y. Kebukawa et al, Sci. Adv. 2017, 3, e1602093.