日本地球惑星科学連合2023年大会

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[J] オンラインポスター発表

セッション記号 M (領域外・複数領域) » M-TT 計測技術・研究手法

[M-TT38] 地球化学の最前線

2023年5月26日(金) 10:45 〜 12:15 オンラインポスターZoom会場 (24) (オンラインポスター)

コンビーナ:鍵 裕之(東京大学大学院理学系研究科附属地殻化学実験施設)、橘 省吾(東京大学大学院理学系研究科宇宙惑星科学機構)、横山 祐典(東京大学 大気海洋研究所 )

現地ポスター発表開催日時 (2023/5/26 17:15-18:45)

10:45 〜 12:15

[MTT38-P04] 高圧下でのアミノ酸から長鎖ペプチドの生成_新たな化学進化の提案

*鍵 裕之1、藤本 千賀子1篠崎 彩子2、三村 耕一3、西田 民人3、森井 尚之1、奈良 雅之4 (1.東京大学 大学院理学系研究科、2.北海道大学 大学院理学研究院、3.名古屋大学 環境学研究科、4.東京医科歯科大学 教養部)

キーワード:高圧、アミノ酸、ペプチド

Amino acids are the building blocks of proteins, and oligomerization of amino acids under prebiotic conditions is one of the essential steps for the origin of life. The oligomerization of amino acids has been reported from high-pressure experiments simulating the impact of comets, hydrothermal vents, and diagenesis in sub-seafloor sedimentary environments (e.g., Sugahara and Mimura, 2015; Imai and Honda, 2010; Otake et al., 2011). Our group has focused on the oligomerization of amino acids under static high-pressure conditions at ambient temperature. Pressure-induced oligomerization of alanine occurred to form alanylalanine (dipeptide of alanine) and trialanine (tripeptide of alanine) at pressures of 5-11 GPa and at 25°C for 2 hours starting from alanine powder soaked in its saturated aqueous solution (Fujimoto et al., 2015). In addition, Takahashi et al. (2017) investigated the mechanism of pressure-induced oligomerization of alanine and raised the possibility that freeze concentration by the crystallization of ice VII, a high-pressure phase of ice, may enhance the pressure-induced oligomerization.
In this study, we further investigated the pressure-induced oligomerization reaction. L-alanine powder was loaded into a metallic gasket without an aqueous pressure medium and pressure was applied up to 16 GPa for 1 hour using an opposed-type sintered diamond anvil with a cup diameter of 3 mm. The recovered sample was dissolved in pure water and analyzed using LC-MS (LCMS-8045, Shimadzu). To determine the structures of long-chained alanine peptides, reference samples were synthesized up to the 13-mer by the solid-phase method using the standard Fmoc strategy.
The sample recovered from high pressure contained alanine peptides up to the 11-mer. The content of peptides decreased with increasing the chain length. In the present study, the formation of the cyclic dimer of alanine, DKP, was below the detection limit. This is consistent with a study on thermodynamic calculations showing that the chain dimer is more stable than DKP at room temperature, in contrast to the higher stability of DKP at high temperatures (Shock, 1992). Our results indicate that the pressurization at room temperature promotes the formation of long-chain peptides without producing DKP, which terminates the formation of chain peptides. This study suggests the possibility of the chemical evolution of amino acids inside the ice planet.