title: Stability of amino acids and their oligomerization under high-pressure conditions: implications for prebiotic chemistry.
abstract: The polymerization of amino acids leading to the formation of peptides and proteins is a significant problem for the origin of life. This problem stems from the instability of amino acids and the difficulty of their oligomerization in aqueous environments, such as seafloor hydrothermal systems. We investigated the stability of amino acids and their oligomerization reactions under high-temperature (180-400°C) and high-pressure (1.0-5.5 GPa) conditions, based on the hypothesis that the polymerization of amino acids occurred in marine sediments during diagenesis and metamorphism, at convergent margins on early Earth. Our results show that the amino acids glycine and alanine are stabilized by high pressure. Oligomers up to pentamers were formed, which has never been reported for alanine in the absence of a catalyst. The yields of peptides at a given temperature and reaction time were higher under higher-pressure conditions. Elemental, infrared, and isotopic analyses of the reaction products indicated that deamination is a key degradation process for amino acids and peptides under high-pressure conditions. A possible NH(3)-rich environment in marine sediments on early Earth may have further stabilized amino acids and peptides by inhibiting their deamination.
authors.affiliation: Department of Earth Science, Graduate School of Science, Tohoku University, Sendai, Japan. totake@m.tohoku.ac.jp
authors.forename: Tsubasa
authors.initials: T
authors.lastname: Otake
authors.forename: Takashi
authors.initials: T
authors.lastname: Taniguchi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Furukawa
authors.forename: Fumio
authors.initials: F
authors.lastname: Kawamura
authors.forename: Hiromoto
authors.initials: H
authors.lastname: Nakazawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kakegawa
mesh_terms: D000409:Alanine / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry*; D018534:Earth, Planet; D019418:Evolution, Chemical; D019143:Evolution, Molecular; D019015:Geologic Sediments / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D006358:Hot Temperature; D009842:Oligopeptides / Q000737:chemistry; D000069497:Origin of Life; D011108:Polymers / Q000737:chemistry; D011312:Pressure; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000596:Amino Acids; D009842:Oligopeptides; D011108:Polymers; D000409:Alanine; D005998:Glycine