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Abstract EANA2024-34



In situ Analytical Methods for Amino Acids and Dipeptides in Space Exposure Experiment

Ai Miyamoto and Hajime Mita
Fukuoka Institute of Technology, Japan


 One of the mysteries of the Earth to date is the origin of life. Since 1969, about 100 amino acids and hydrocarbons have been found on a meteorite that fell to Murchison, Australia, and glycylglycine was the only peptide found in the meteorite. It is important to investigate whether peptides are formed in space to clarify the birthplace of life. In the Tanpopo experiments, amino acids were exposed to space on the International Space Station (ISS) and dipeptides were formed in space under ultraviolet light. The next new space station, Gateway, is currently under construction in lunar orbit. Although the ISS is exposed to high levels of ultraviolet radiation, it is protected from cosmic rays by the Van Allen belts. On the other hand, since cosmic rays are also strong at the Gateway. Therefore, the analysis of dipeptide formation on the Gateway is important to study the origin of life in the deep space. It is necessary to analyze the exposed samples in situ since there is little possibility of bringing them back to Earth at the Gateway. Therefore, we will develop a method to analyze amino acid degradation and dipeptide formation by imaging in space orbit in a future automated and simple way on a cubic SAT scale. 

 Amino acid monomers (D-alanine, L-alanine, glycine) and dipeptides (glycylglycine, alanylalanine) were used for FT-IR measurement and colorimetric analysis by ninhydrin reaction and biuret reaction.

 The ninhydrin reaction, stained both alanine and alanylalanine. The reaction is a method for detecting the amino group of amino acids, not peptides. Because alanylalanine is a small molecule, ninhydrin reacts with the amino group of alanylalanine and gives a blue-violet to red-violet color. Therefore, the ninhydrin reaction is not considered suitable for distinguishing between amino acids and peptides.

 In the biuret reaction, alanine did not stain, but alanylalanine stained slightly blue. Originally, the biuret reaction is a detection method for polypeptides higher than tripeptide, and the reaction caused a reddish-purple to bluish-purple staining. Since the samples used were amino acid and dipeptide, the reaction should not normally occur. However, even dipeptides did not turn purple, but changed enough to be distinguishable from amino acids. Based on this result, TLC analysis was performed with alanine and alanylalanine after the reaction. The bands were confirmed only for alanylalanine. We believe that a method combining the biuret reaction and TLC analysis can be used in the future, and we will study the details of this method. In addition, since the yield of dipeptides produced in space is low, research will be conducted to improve the accuracy so that a very small amount of produced dipeptides can be detected while leaving a large amount of amino acids as the raw material remains. Since the color reaction alone is difficult to analyze and TLC is to be combined with the color reaction, we will add other derivatization reactions to the study. To this end, we have started to study dabsylation first.