ABSTRACT

Enthalpies of solution of glycine, L-alanine, L-serine, L-threonine, L-valine, diglycine and triglycine in aqueous solutions of trimethylamine N-oxide (TMAO) have been measured by calorimetry at 298.15 K. The results obtained were used to calculate the heterogeneous enthalpic interaction coefficients ( hAT ) between the amino acids or glycine peptides and the molecule of TMAO in water. These solution enthalpies have been used to calculate the transfer enthalpies () of the amino acids or glycine peptides from water to aqueous solutions of TMAO. It has been observed that the transfer enthalpies of the amino acids and glycine peptides from water to aqueous solutions of TMAO are monotonically positive over the investigated concentration ranges. The relative order of hAT and for amino acids are all L-serine greater than L-threonine greater than glycine greater than L-alanine greater than L-valine, whereas the sequence of glycine peptides is triglycine greater than diglycine greater than glycine. The results are discussed in terms of solute-solute and solute-solvent interactions.

Compounds

#	Formula	Name
1	C3H9NO	trimethylamine oxide
2	C2H5NO2	2-aminoacetic acid
3	C3H7NO2	(S)-2-aminopropanoic acid
4	C3H7NO3	L-serine
5	C4H9NO3	L-threonine
6	C5H11NO2	L-valine
7	C4H7NO4	N-(carboxymethyl)glycine
8	C6H11N3O4	glycylglycylglycine
9	H2O	water

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Constraint	Phase	Method	#Points
POMD	2 1 9	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Molality, mol/kg - 1; Liquid	Molality, mol/kg - 2; Liquid Pressure, kPa; Liquid Temperature, K; Liquid	Liquid	Calvet calorimetry	7
POMD	4 1 9	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Molality, mol/kg - 1; Liquid	Molality, mol/kg - 4; Liquid Pressure, kPa; Liquid Temperature, K; Liquid	Liquid	Calvet calorimetry	7
POMD	5 1 9	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Molality, mol/kg - 1; Liquid	Molality, mol/kg - 5; Liquid Pressure, kPa; Liquid Temperature, K; Liquid	Liquid	Calvet calorimetry	7
POMD	3 1 9	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Molality, mol/kg - 1; Liquid	Molality, mol/kg - 3; Liquid Pressure, kPa; Liquid Temperature, K; Liquid	Liquid	Calvet calorimetry	7
POMD	6 1 9	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Molality, mol/kg - 1; Liquid	Molality, mol/kg - 6; Liquid Pressure, kPa; Liquid Temperature, K; Liquid	Liquid	Calvet calorimetry	7
POMD	7 1 9	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Molality, mol/kg - 1; Liquid	Molality, mol/kg - 7; Liquid Pressure, kPa; Liquid Temperature, K; Liquid	Liquid	Calvet calorimetry	7
POMD	8 1 9	Molar enthalpy of solution, kJ/mol ; Liquid	Solvent: Molality, mol/kg - 1; Liquid	Molality, mol/kg - 8; Liquid Pressure, kPa; Liquid Temperature, K; Liquid	Liquid	Calvet calorimetry	7
POMD	2 9	Molar enthalpy of solution, kJ/mol ; Liquid	Molality, mol/kg - 2; Liquid Pressure, kPa; Liquid Temperature, K; Liquid		Liquid	Calvet calorimetry	1
POMD	4 9	Molar enthalpy of solution, kJ/mol ; Liquid	Molality, mol/kg - 4; Liquid Pressure, kPa; Liquid Temperature, K; Liquid		Liquid	Calvet calorimetry	1
POMD	5 9	Molar enthalpy of solution, kJ/mol ; Liquid	Molality, mol/kg - 5; Liquid Pressure, kPa; Liquid Temperature, K; Liquid		Liquid	Calvet calorimetry	1
POMD	3 9	Molar enthalpy of solution, kJ/mol ; Liquid	Molality, mol/kg - 3; Liquid Pressure, kPa; Liquid Temperature, K; Liquid		Liquid	Calvet calorimetry	1
POMD	6 9	Molar enthalpy of solution, kJ/mol ; Liquid	Molality, mol/kg - 6; Liquid Pressure, kPa; Liquid Temperature, K; Liquid		Liquid	Calvet calorimetry	1
POMD	7 9	Molar enthalpy of solution, kJ/mol ; Liquid	Molality, mol/kg - 7; Liquid Pressure, kPa; Liquid Temperature, K; Liquid		Liquid	Calvet calorimetry	1
POMD	8 9	Molar enthalpy of solution, kJ/mol ; Liquid	Molality, mol/kg - 8; Liquid Pressure, kPa; Liquid Temperature, K; Liquid		Liquid	Calvet calorimetry	1

Thermodynamics Research Center / ThermoML | Thermochimica Acta

Transfer Enthalpies of Amino Acids and Glycine Peptides from Water to Aqueous Solutions of Trimethylamine N-oxide at 298.15 K

Wang, X.[Xu], Guo, Y.[Yuhua], Zheng, Q.[Qing], Lin, R.[Ruisen]

ABSTRACT