Cation Effect on the Water Activity of Ternary (S)-Aminobutanedioic Acid Magnesium Salt Solutions at 298.15 and 310.15 K

Abstract

Vapor pressure osmometry was applied to the system aminomethanamidine hydrochloride (guanidinium hydrochloride, GndmCl) + (S)aminobutanedioic acid hemimagnesium salt (magnesium L-aspartate, Mg-(L-Asp) 2 ) + water for varying molalities of GndmCl and Mg-(L-Asp) 2 (m Mg-(Asp) 2 = 0.1, 0.2, and 0.3 mol/kg and m GndmCl = 0.1−1.2 mol/kg) at T = 298.15 and 310.15 K. From vapor pressure osmometry, activities of water, activity coefficients of water, and the corresponding osmotic coefficients of the mixtures Mg-(L-Asp) 2 + water and Mg-(L-Asp) 2 + GndmCl + water have been calculated, both being directly related to the chemical potentials of the different species and therefore to their Gibbs energy. Electrolyte perturbed-chain statistical associating fluid theory (ePC-SAFT) accounting for Coulomb and short-range (hard chain, dispersion, association) interactions was used to model the own experimental data of binary Mg-(L-Asp) 2 + water and ternary GndmCl + Mg-(L-Asp) 2 + water solutions. ePC-SAFT was further applied to model osmotic coefficients of NaGlu + KCl + water, NaGlu + NaCl + water, NaAsp + NaCl + water, NaAsp + KCl + water, aminoethanoic acid + NaNO 3 + water, and aminoethanoic acid + NaSCN + water as well as thermodynamic properties of these solutions such as fugacity coefficients and activity coefficients of the mixture components. Without fitting any parameters to data of the ternary salt + aminoethanoic acid + water system, osmotic coefficients, ϕ, and activity coefficients of water, γ 1 , and aminoethanoic acid have been predicted, and ϕ and γ 1 were in good agreement with the experimental data. In contrast, a negative binary interaction parameter k ij had to be introduced to model ϕ of ternary systems salt + amino acid salt + water in accurate agreement with the experimental data.

Influence of pH Value and Ionic Liquids on the Solubility of l-Alanine and l-Glutamic Acid in Aqueous Solutions at 30 °C

“… a Reference . b Reference . c k ij = 0.000291 × T [K] – 0.14796. d Reference . e σ water = 2.7927 + 10.11 exp­(−0.01775 × T [K]) – 1.417 exp­(−0.01146 × T [K]). f Reference . g this work …”

Crowders and Cosolvents—Major Contributors to the Cellular Milieu and Efficient Means to Counteract Environmental Stresses

“…Impacts on stability, equilibrium or kinetics have often been explained by cosolute-induced volume effects. [74,[262][263][264][265] Recently,t hermodynamic activity was used to explain such behaviors [266][267][268][269][270][271][272][273] by taking into account the real-mixture behavior of multi-component solutions, which is determined by ideal and non-ideal mixture contributionst ot he chemical potentialo ft he mixture's constituents. For liquid mixtures, deviations from ideal mixture behavior are characterized by the activity coefficients of the constituents,w hichh ave an impact on the thermodynamic reaction equilibrium and on the reactionk inetics.…”

“…[294][295][296] To overcome this limitation, modelsh ave been developed that account also for the non-spherical shapes of molecules, and include repulsive interactions as well as dispersive, associative (hydrogen bonds), polar,a nd ionic interactions, such as the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT). [289] PC-SAFT has been used to predict activityc oefficients of biomolecules in aqueous multi-component solutionsc ontaining cosolutes such as amino acids, [273,291,297,298] salts, [299][300][301][302] osmolytes, [293,299] organic solvents, [292,300] and sugars. [292] The availability of such predictive thermodynamic models is an important step towards 1. determining the activity-based valueso fK a M and K th according to Equations (14) and (15), and 2. the use of K a M and K th to predict the equilibrium position and reaction rates at different solutionc onditions by accounting for activity coefficients.…”

Guanidinium Cation Effect on the Water Activity of Ternary (S)Aminopentanedioic Acid Sodium Salt Solutions at 298.15 and 310.15 K

“…In contrast, molecular interactions between GndmCl and NaGlu differ from the strong interactions found between NaAsp and GndmCl in aqueous solutions, in which stronger short-range interactions occur caused by structural correspondence of aspartate and guanidinium ions. 10 In more detail, these interactions occur because of the fact that Gndm + and Asp − ions possess oppositely charged donor−acceptor centers: two amino groups in Gndm + and two COO − groups in Asp − , and an amino group in Asp − ion and an imino group in Gndm + . In contrast, the COO − groups of the glutamate anion are surrounded with additional CH 2 groups; that is, geometric correspondence is not fulfilled and the interaction is much weaker.…”

“…Glutamate and aspartate belong to the anions of polar hydrophilic amino acids with two charged carboxylic groups, which play an important role in protein affinities. In our previous work, the aspartate anion has been shown to form complexes with guanidinium. In this work, the ion-specific interactions of guanidinium cation with the anion of the polar hydrophilic proteinogene amino acid–glutamic acid is studied.…”