Percorrer por autor "Javornik, Ema"
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- Partial molar volumes of amino acids in aqueous solutions of magnesium chloridePublication . Ferreira, Olga; Javornik, Ema; Pinho, SimãoThe lack of a deep molecular picture of the interactions which govern the biochemistry of vital processes is still one critical issue in this area, which limits the development of pharmaceutical solutions for diseases induced by biochemical disorders [1] and the improvement of the efficiency of biotechnological processes [2]. In this concern the study of protein-electrolyte interactions is of most importance. Hydrophobic, charged atomic groups and ions are components of almost every biologically important systems, but proteins are so complex that is useful to investigate the interaction of model compounds such as amino acids [3]. In the last decade much attention has been devoted to the partial molar volumes and hydration properties of amino acids in electrolyte solutions, which are the subject of this study.
- Volumetric interactions of a series of α-amino acids in aqueous magnesium chloride solutions at 278.15, 288.15, 298.15, and 308.15 KPublication . Javornik, Ema; Ferreira, Olga; Pinho, SimãoIn this work, the partial molar volumes of glycine, l-alanine, l-valine, l-serine, and l-threonine in aqueous solutions of magnesium chloride at 0.0, 0.1, 0.3, 0.7, and 1.0 molal are addressed between 278.15 and 308.15 K. Volumes of transfer were obtained, following the rank serine > glycine a parts per thousand threonine > alanine > valine. Differently, the hydration numbers follow the sequence serine > valine > alanine > threonine > glycine, and dehydration of the amino acids is observed, rising the temperature or salt molality. The data suggest that interactions are mainly pairwise, between the ions and charged/hydrophilic groups of the amino acids. Within the Friedman and Krishnan formalism, a group-contribution scheme has been successfully applied to the pairwise volumetric interaction coefficient. Finally, the dehydration effect of MgCl2 on glycine, alanine, and serine has been predicted applying empirical correlations developed before, showing satisfactory results.