Thermal reaction kinetics of the glutamic acid-pyroglutamic acid system in water

Povoledo, D.; Vallentyne, J. R.

doi:10.1016/0016-7037(64)90089-4

Cited by 39 publications

(28 citation statements)

References 6 publications

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“…However, several experiments on individual organic compounds, or well characterized groups of compounds, have been conducted. Many such experiments have been conducted for amino acids (Abelson, 1954;Vallentyne, 1964Vallentyne, , 1968Povoledo and Vallentyne, 1964;White, 1984;Bernhardt et al, 1984;Miller and Bada, 1988). In principle, it should be possible to evaluate the results of these experiments in a thermodynamic framework.…”

Section: Evidence From Hydrous Pyrolysis Experimentsmentioning

confidence: 98%

Geochemical constraints on the origin of organic compounds in hydrothermal systems

Shock

1990

Origins Life Evol Biosphere

274

182

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Abstract. It is proposed that abiotic synthesis of organic compounds occurs in metastable states. These states are permitted by kinetic barriers which inhibit the approach to stable equilibrium in the C-H-O-N system. Evidence for metastable equilibrium among organic compounds in sedimentary basins is reviewed, and further evidence is elucidated from hydrous pyrolysis experiments reported in the literature. This analysis shows that at hydrothermal conditions, organic compounds are formed or destroyed primarily through oxidation/reduction reactions, and that the role of temperature is to lower the kinetic barriers to these reactions. These lines of evidence allow the development of a scenario in which abiotic synthesis can occur at hydrothermal conditions through the reduction of CO2 and N2. This scenario can be tested quantitatively with distribution of species calculations as functions of temperature, pressure, hydrogen fugacity (JH~) and initial composition. One example of such a test is given for an early, sudden outgassing of the Earth, in which CO2, H20, and N2 are transported from the mantle to the atmosphere by hydrothermal solutions. Activities of metastabte aqueous organic species which form as a consequence of this process are evaluated at conditions appropriate for seafloor hydrothermat systems, and are found to maximize at about 200 °C and between the oxidation states set by two mineral assemblages common in the oceanic crust.

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Section: Evidence From Hydrous Pyrolysis Experimentsmentioning

confidence: 98%

Geochemical constraints on the origin of organic compounds in hydrothermal systems

Shock

1990

Origins Life Evol Biosphere

274

182

View full text Add to dashboard Cite

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“…Conductivity measurements of amino acid ionization constants are impractical because, according to reactions 1 and 2, an excess of acid or base is required to drive the ionization. The use of pH titrations in the usual stirred hydrogen concentration cells (Mesmer et al, 1970) to study amino acids is limited to relatively low temperatures because amino acids have limited stability under hydrothermal conditions (Povoledo and Vallentyne, 1964;Vallentyne, 1964Vallentyne, , 1968Bada and Miller, 1970). The length of time required to achieve thermal equilibrium and to conduct the titration causes the amino acids to decompose.…”

Section: Introductionmentioning

confidence: 99%

Ionization constants of aqueous amino acids at temperatures up to 250°C using hydrothermal pH indicators and UV-visible spectroscopy: Glycine, α-alanine, and proline

Clarke

Collins

Roberts

et al. 2005

Geochimica et Cosmochimica Acta

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Abstract-Ionization constants for several simple amino acids have been measured for the first time under hydrothermal conditions, using visible spectroscopy with a high-temperature, high-pressure flow cell and thermally stable colorimetric pH indicators. This method minimizes amino acid decomposition at high temperatures because the data can be collected rapidly with short equilibration times. The first ionization constant for proline and ␣-alanine, K a,COOH , and the first and second ionization constants for glycine, K a,COOH and K a,NH4ϩ , have been determined at temperatures as high as 250°C. Values for the standard partial molar heat capacity of ionization, ⌬ r C p o , COOH and ⌬ r C p o , NH4ϩ , have been determined from the temperature dependence of ln (K a,COOH ) and ln (K a,NH4ϩ ). The methodology has been validated by measuring the ionization constant of acetic acid up to 250°C, with results that agree with literature values obtained by potentiometric measurements to within the combined experimental uncertainty.We dedicate this paper to the memory of Dr. Donald Irish (1932-2002 of the University of Waterloofriend and former supervisor of two of the authors (R.J.B. and P.R.T.).

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“…22,23 Thus, we attempted to detect PyroGlu in the mixed solution CRMs using LC/MS. As expected, PyroGlu was detected in the mixed solution CRM 1 ( Fig.…”

Section: Instability Of Glutamic Acid In Amino Acid Mixed Solutionsmentioning

confidence: 99%

Effects of the pH and Concentration on the Stability of Standard Solutions of Proteinogenic Amino Acid Mixtures

et al. 2017

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To prepare metrologically traceable amino acid mixed standard solutions, it is necessary to determine the stability of each amino acid present in the mixed solutions. In the present study, we prepared amino acid mixed solutions using certified reference standards of 17 proteinogenic amino acids, and examined the stability of each of these amino acids in 0.1 N HCl. We found that the concentration of glutamic acid decreased significantly during storage. LC/MS analysis indicated that the instability of glutamic acid was due to the partial degradation of glutamic acid to pyroglutamic acid in 0.1 N HCl. Using accelerated degradation tests, we investigated several solvent compositions to improve the stability of glutamic acid in amino acid mixed solution, and determined that the change of the pH by diluting the mixed solution improved the stability of glutamic acid.

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Thermal reaction kinetics of the glutamic acid-pyroglutamic acid system in water

Cited by 39 publications

References 6 publications

Geochemical constraints on the origin of organic compounds in hydrothermal systems

Geochemical constraints on the origin of organic compounds in hydrothermal systems

Ionization constants of aqueous amino acids at temperatures up to 250°C using hydrothermal pH indicators and UV-visible spectroscopy: Glycine, α-alanine, and proline

Effects of the pH and Concentration on the Stability of Standard Solutions of Proteinogenic Amino Acid Mixtures

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