Japan Geoscience Union Meeting 2016

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International Session (Oral)

Symbol B (Biogeosciences) » B-AO Astrobiology & the Origin of Life

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

Tue. May 24, 2016 3:30 PM - 5:00 PM A01 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Kensei Kobayashi(Department of Chemistry and Biotechnology, Faculty of Engineering, Yokohama National University), Akihiko Yamagishi(Tokyo University of Pharmacy and Life Science, Department of Molecular Biology), Masatoshi Ohishi(Astronomy Data Center, National Astronomical Observatory of Japan), Eiichi Tajika(Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo), Takeshi Kakegawa(Graduate School of Science, Tohoku University), Shigeru Ida(Department of Earth and Planetary Science, Graduate School of Science and Technology, Tokyo Institute of Technology), Mary Voytek(NASA Headquarter), Joseph Kirschvink(Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA), Chair:Eiichi Tajika(Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo), Takeshi Kakegawa(Graduate School of Science, Tohoku University)

4:00 PM - 4:15 PM

[BAO01-09] Epimerization of oligopeptides induced by radiation rays

*Toratane Munegumi1 (1.Department of Science Education, Naruto University of Education)

Keywords:epimerization, oligopeptides, gamma rays

Proteins just after translation are composed of L-form homochiral amino acids. The formation process of homochiral polypeptides, which are fundamental for proteins, has not been elucidated. Although many hypotheses have been proposed, most of those relate to explaining the one-handed structure of amino acids. This research focuses the reactivity of oligopeptides to discuss epimerization of oligopeptides induced by irradiation using gamma rays and discharges, and the difference in epimerization rate between diastereomers.
Linear and cyclic alanine dipeptides were irradiated in solution or as solid state by gamma rays (1-24 kGy). The resulted reaction solutions were analyzed by means of HPLC equipped with achiral or chiral columns. Linear L-Ala-L-Ala epimerized faster (reaction rate constant: 0.017kGy-1) than D-Ala-L-Ala (0.0033kGy-1) in 1mM solutions. This suggests that such reaction conditions are not suited for accumulation of homochiral peptides. However, the results in the reactions using cyclic dipeptides showed heterochiral peptides epimerizes faster than homochiral peptides.