Thermodynamic Properties of L-Aspartates of Alkali and Alkali-Earth Metals in Aqueous Solutions at 298.15 and 310.15 K and Specific Cation Effects on Biomolecule Solvation

Tsurko, Elena N. and Neueder, Roland and Kunz, Werner (2018) Thermodynamic Properties of L-Aspartates of Alkali and Alkali-Earth Metals in Aqueous Solutions at 298.15 and 310.15 K and Specific Cation Effects on Biomolecule Solvation. JOURNAL OF SOLUTION CHEMISTRY, 47 (4). pp. 727-748. ISSN 0095-9782, 1572-8927

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Abstract

Vapor pressure osmometry was applied to the systems calcium l-aspartate ((S)-aminobutanedioic acid calcium salt) + water for varying molalities of Ca-l-Asp (m (Ca-l-Asp) = 0.01-1.02 mol center dot kg(-1)) and guanidinium hydrochloride (methanamidine hydrochloride) + sodium L-aspartate ((S)-aminobutanedioic acid sodium salt) + water, varying the molalities of GndmCl and Na-l-Asp (m (Na-l-Asp) = 0.1, 0.25, 0.4, 0.57 mol center dot kg(-1) and m (GndmCl) = 0.1-1.1 mol center dot kg(-1)) at T = 298.15 K and 310.15 K. From vapor pressure osmometry, activities of water, and the corresponding osmotic coefficients of the mixtures Ca-l-Asp + water and Na-l-Asp + GndmCl + water have been calculated, both being directly related to the chemical potentials of the different species and therefore to their Gibbs energy. Mean molal ion activity coefficients were obtained from experimental data fits with the Pitzer equations and the corresponding dual and triple interaction parameters were derived for the Ca-l-Asp + water binary system. beta ((2)) Pitzer parameters different from zero are required for Ca-l-Asp in water to reproduce the osmotic coefficient decrease with increasing concentration. Mean Spherical Approximation parameters accounting for Coulomb and short range interactions that describe the calcium and magnesium aspartates and glutamates are given. The decrease in the chemical potential of the aspartates corresponds to the Hofmeister series: NaAsp > Mg(Asp)(2) > CaAsp. A strong interaction between amino acid and salt due to specific dispersion interactions in amino acid salt systems containing guanidinium based salt has been revealed that is in agreement with MD and half-empirical quantum-chemical calculations.

Item Type: Article
Uncontrolled Keywords: OSMOTIC COEFFICIENTS; VOLUMETRIC PROPERTIES; VAPOR-PRESSURES; WATER ACTIVITY; SALT-SOLUTIONS; AMINO-ACIDS; SODIUM; ELECTROLYTES; INTERFACE; GLUTAMATE; Vapor pressure osmometry; Osmotic coefficient; Calcium L-aspartate; Sodium L-aspartate; Guanidinium hydrochloride; Electrolyte; Activity coefficient
Subjects: 500 Science > 540 Chemistry & allied sciences
Divisions: Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie
Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > Prof. Dr. Werner Kunz
Depositing User: Dr. Gernot Deinzer
Date Deposited: 10 Mar 2020 13:51
Last Modified: 10 Mar 2020 13:51
URI: https://pred.uni-regensburg.de/id/eprint/14766

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