[U-12] Biogeochemistry of CO world

[U12-P04] Effect of sulfur-containing amino acid on peptide formation by solar energy particle irradiation in early terrestrial and martin atmospheres

*Nanaka Kogi¹, Tomoki Kimura¹, Hidetaka Torigoe¹, Kensei Kobayashi², Nobuaki Okumura³, Kosuke Fukui¹, Yuki Sakurai¹, Yayoi Yoshimura¹, Naoki Terada⁴ (1.Tokyo University of Science, 2.Faculty of Engineering, Yokohama National University, 3.Institute for Protein Research, Osaka University, 4.Graduate School of Science, Tohoku University)

Keywords:Early earth, Early mars, Origin of life, Amino acid

The origin of amino acids and proteins required for the emergence of life on the planets that have the ocean and atmosphere is an unresolved big problem. Particularly, it is important to elucidate the origin of peptides, the precursors of proteins, to understand the processes by which proteins are formed from amino acids. Since the 1950s, it has been reported that amino acids and other important organic matters can be produced from gas samples simulating early planetary atmospheres by injecting various energy sources in laboratory experiments [e.g., Miller & Urey, 1959; Kobayashi et al. 1998; Chyba & Sagan, 1991].Sakurai et al. [JpGU, 2024] newly added sulfur-containing amino acids (cysteine) simulating volcanic gases to powder amino acid samples (glycine, alanine, and serine) that could be synthesized in the early Martian atmosphere [Kobayashi et al., 1989], and irradiated with hydrogen ion molecules simulating Solar Energetic Particles (SEP). As a result, peptide formation was only observed in irradiated samples of sulfur-containing amino acids. This can be interpreted as the sulfur-containing amino acids facilitating the binding of other amino acids by irradiation, resulting in the formation of peptides. However, other necessary conditions, such as combinations of amino acids, which are effective for peptide production, remain unexplored. In this study, we simplify the combination of sample amino acids and irradiated them with molecular hydrogen ions (10.0 keV or 8.50 keV, 7 µA) to search for the necessary conditions for the peptide formation. High-performance liquid chromatography of aqueous solutions of irradiated samples showed no effect of irradiation in a pure sulfur-containing amino acid sample, but several irradiation products were detectable only in irradiated samples in which sulfur-containing amino acids mixed with other amino acids. Amino acids containing carbon atom in the side chain, such as alanine and serine, were more efficient in producing irradiation products when mixed with cysteine. N-terminal amino acid sequence analysis of these products showed a peak after the second cycle after Edman degradation, suggesting that the irradiated products were peptides.The combination of sulfur-containing amino acid (cysteine) and other amino acids is a prerequisite for the formation of peptides by the SEP irradiation of atmosphere including volcanic gasses on early Mars and Earth. Particularly it is suggested that the presence of both cysteine and other amino acids with carbon atom in the side chain may efficiently promote the bonding of amino acids leading formation of peptides. We will analyze the amino acid sequence of the irradiation product, the peptide, to determine its structure. In this presentation, we report the current status of our study.