日本地球惑星科学連合2015年大会

講演情報

インターナショナルセッション(口頭発表)

セッション記号 B (地球生命科学) » B-AO 宇宙生物学・生命起源

[B-AO01] Astrobiology: Origins, Evolution, Distribution of Life

2015年5月27日(水) 16:15 〜 18:03 105 (1F)

コンビーナ:*小林 憲正(横浜国立大学大学院工学研究院)、山岸 明彦(東京薬科大学生命科学部)、大石 雅寿(国立天文台天文データセンター)、田近 英一(東京大学大学院新領域創成科学研究科複雑理工学専攻)、掛川 武(東北大学大学院理学研究科地学専攻)、井田 茂(東京工業大学大学院理工学研究科地球惑星科学専攻)、座長:掛川 武(東北大学大学院理学研究科地学専攻)、井田 茂(東京工業大学大学院理工学研究科地球惑星科学専攻)

17:45 〜 17:48

[BAO01-P07] アスパラギン酸の重合形態に及ぼすpHの影響

ポスター講演3分口頭発表枠

*岡田 陽介1掛川 武1古川 善博1 (1.東北大学大学院理学研究科地学専攻)

Proteins, which have important roles as enzymes in many biological reactions, are consisted of 20 kinds of L-α-amino acids. These amino acids are connected with peptide bonds that combine N in α-amino group to C in α-carboxyl group. There are several proteinogenic amino acids containing two carboxyl groups or two amino groups. Even these amino acids, natural peptide bond found in proteins connects the α-amino group to the α-carboxyl group. The regioselective peptide bounding might have been formed in early stage of chemical evolution because reactive side chain of these amino acids are important for basic functions of proteins. In such case, geological setting or geological events must lead the regioselective peptide bound. In this study, we tried to constrain geological setting for regionselectivity using aspartic acid (Asp) as a model amino acid. Asp has α- and β-carboxyl group that have slightly different pKa. To evaluate favorable geological settings for peptide formation with α-carboxyl carbon, we investigated the effects by different pH at high temperature and high pressure simulating difference in pH of pore water in deep-sea sediments. Asp solutions with pH ranging from 1.5 to 12.1 were heated and compressed for 1–8 days at 100 ℃ and 100 MPa. After incubation, the products were analyzed by liquid chromatography mass spectrometry. We also investigated the effects by pH on decomposition rate of Asp to evaluated suitable pH conditions for α-peptide formation. The decomposition rates of Asp were greater in higher pH and the peptides formed were different with varying pH. These results suggest that environments suitable for α-peptide formation were limited by pH.