title: Reaction behaviors of glycine under super- and subcritical water conditions.
abstract: The influence of temperature and pressure on the dimerization and decomposition of glycine under simulated hydrothermal system conditions was studied by injecting a glycine solution into water in the sub- and supercritical state. The experiments at five different temperatures of supplied water--250, 300, 350, 374, and 400 degrees C--were performed at 22.2 and 40.0 MPa. At 350 degrees C, experiments under 15.0-40.0 MPa were conducted. Diglycine, triglycine (trace), diketopiperazine, and an unidentified product with a high molecular mass (433 Da) were the main products of oligomerization. The results show that temperature and pressure influence the extent of dimerization and decomposition of glycine. The maximum of dimers formation was observed at 350 and 375 degrees C at 22.2 and 40.0 MPa, respectively, and coincided with a high rate of glycine decomposition. Glycine, alanine, aspartic acid, as well as other amino acids, were obtained by injecting a mixture of formaldehyde and ammonia. The results support the oligomerization and synthesis of amino acids in a submarine hydrothermal system.
authors.affiliation: DEEPSTAR Group, Japan Marine Science and Technology Center, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan.
authors.forename: Dimitar K
authors.initials: DK
authors.lastname: Alargov
authors.forename: Shigeru
authors.initials: S
authors.lastname: Deguchi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tsujii
authors.forename: Koki
authors.initials: K
authors.lastname: Horikoshi
mesh_terms: D000596:Amino Acids / Q000138:chemical synthesis; D000641:Ammonia / Q000737:chemistry; D054659:Diketopiperazines; D019281:Dimerization; D019418:Evolution, Chemical; D005557:Formaldehyde / Q000737:chemistry; D005998:Glycine / Q000737:chemistry*; D009842:Oligopeptides / Q000737:chemistry; D000069497:Origin of Life; D010879:Piperazines / Q000737:chemistry; D011312:Pressure; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D054659:Diketopiperazines; D009842:Oligopeptides; D010879:Piperazines; D014867:Water; D005557:Formaldehyde; D000641:Ammonia; C035647:glycyl-glycyl-glycine; D005998:Glycine