Amino Acids under Hydrothermal Conditions:  Apparent Molar Volumes of Aqueous α-Alanine, β-Alanine, and Proline at Temperatures from 298 to 523 K and Pressures up to 20.0 MPa

and, Rodney G. Clarke; Tremaine, Peter R.

doi:10.1021/jp984791r

Cited by 44 publications

(93 citation statements)

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“…Our earlier studies in a platinum vibrating tube densitometer and flow microcalorimeter, which used very similar injection systems constructed of platinum (Clarke and Tremaine, 1999;, showed no detectable decomposition of glycine at 225°C, or of ␣-alanine and proline at 250°C. We subsequently collected samples of our glycine and proline solutions which had been injected through the titanium UV-visible system at the identical flow rate used in these experiments (0.2 cm 3 .min Ϫ1 ) for analysis by 13 C-NMR.…”

Section: Methodsmentioning

confidence: 83%

“…In addition, although the zwitterionic amino acid product in reaction (3), AH Ϯ (aq), carries no net charge, it also has sufficient polarizing power to increase its hydration under hydrothermal conditions (Clarke and Tremaine, 1999). Finally, these experimental dissociation constants confirm the estimated values used in calculations by Clarke and Tremaine (1999) and to show that the standard partial molar volumes and heat capacities of zwitterionic amino acids behave like electrolytes rather than typical non-electrolytes, in that their temperature-dependence is consistent with negative rather than positive discontinuities at the critical point of water.…”

Section: Discussionmentioning

confidence: 99%

“…Heat-of-mixing flow calorimetry has been used to determine ionization constants and enthalpies of reaction for the protonation of the amino and carboxylate groups of several amino acids at temperatures of up to 125°C (Izatt et al, 1992;Gillespie et al, 1995;Wang et al, 1996). Vibrating-tube densimeters and a Picker-type flow microcalorimeter have recently been used to determine experimental values for the standard partial molar volumes and heat capacities of glycine, ␣-alanine, ␤-alanine, proline, and the dipeptide glycyl-gylcine, at temperatures as high as 275°C (Hakin et al, 1995(Hakin et al, , 1998Clarke and Tremaine, 1999;. We are aware of no other experimental studies on the thermodynamic properties of aqueous amino acids or peptides above 100°C.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Methodsmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…The hydration contribution (v 2;1/hyd )is negative, as a consequence of that the specific volume of water molecules in bulk is larger than the specific volume in the hydration shell. The contributions to the partial specific adiabatic compressibility are the free volume and hydration because the effect of the pressure on the atomic volume is neglected [10,[12][13][14][15][16][17][18][19][20][21]:…”

Section: And Similarly Tomentioning

confidence: 99%

Determination of Thermodynamic Partial Properties in Multicomponent Systems by Titration Techniques

Corea¹,

Grolier²,

Rı́o³

2017

Advances in Titration Techniques

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Thermodynamic experimental techniques using titration are usually employed to study the interaction between solutes in a diluted solution. This chapter deals with the underlying thermodynamic framework when titration technique is applied with densimetry, sound speed measurement and isothermal titration calorimetry. In the case of partial volumes and partial adiabatic compressibilities, a physical interpretation is proposed based upon atomic, free volume and hydration contributions.

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“…Experimental values of V • of Gly, Pro, and Ser at temperatures >100 • C (Clarke and Tremaine, 1999;Marriott et al, 2001) were combined with correlated values of ω to calculate values of V • n . There is an overall linear trend apparent in the regression plots for V • n shown in Fig.…”

Section: Retrieval Of the Solvation Parametermentioning

confidence: 99%

Temperature, pressure, and electrochemical constraints on protein speciation: Group additivity calculation of the standard molal thermodynamic properties of ionized unfolded proteins

2006

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Abstract. Thermodynamic calculations can be used to quantify environmental constraints on the speciation of proteins, such as the pH and temperature dependence of ionization state, and the relative chemical stabilities of proteins in different biogeochemical settings. These calculations depend in part on values of the standard molal Gibbs energies of proteins and their ionization reactions as a function of temperature and pressure. Because these values are not generally available, we calculated values of the standard molal thermodynamic properties at 25 • C and 1 bar as well as the revised Helgeson-Kirkham-Flowers equations of state parameters of neutral and charged zwitterionic reference model compounds including aqueous amino acids, polypeptides, and unfolded proteins. The experimental calorimetric and volumetric data for these species taken from the literature were combined with group additivity algorithms to calculate the properties and parameters of neutral and ionized sidechain and backbone groups in unfolded proteins. The resulting set of group contributions enables the calculation of the standard molal Gibbs energy, enthalpy, entropy, isobaric heat capacity, volume, and isothermal compressibility of unfolded proteins in a range of proton ionization states to temperatures and pressures exceeding 100 • C and 1000 bar. This approach provides a useful frame of reference for thermodynamic studies of protein folding and complexation reactions. It can also be used to assign provisional values of the net charge and Gibbs energy of ionized proteins as a function of temperature and pH. Using these values, an Eh-pH diagram for a reaction representing the speciation of extracellular proteins from Pyrococcus furiosus and Bacillus subtilis was generated. The predicted predominance limits of these proteins correspond with the different electrochemical conditions of hydrothermal vents and soils. More comprehensive calculations of this kind may reveal pervasive chemical potential constraints on the interactions of microbes with their environment.

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Amino Acids under Hydrothermal Conditions: Apparent Molar Volumes of Aqueous α-Alanine, β-Alanine, and Proline at Temperatures from 298 to 523 K and Pressures up to 20.0 MPa

Cited by 44 publications

References 58 publications

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

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

Determination of Thermodynamic Partial Properties in Multicomponent Systems by Titration Techniques

Temperature, pressure, and electrochemical constraints on protein speciation: Group additivity calculation of the standard molal thermodynamic properties of ionized unfolded proteins

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