The acid–base properties of γ-l-glutamyl-l-cysteinyl-glycine (glutathione, GSH) were determined by potentiometry (ISE-H+, glass electrode) in pure NaI(aq) and in NaCl(aq)/MgCl2(aq), and NaCl(aq)/CaCl2(aq) mixtures, at T = 298.15 K and different ionic strengths (up to I c ~ 5.0 mol L−1). In addition, the activity coefficients of glutathione were also determined by the distribution method at the same temperature in various ionic media (LiCl(aq), NaCl(aq), KCl(aq), CsCl(aq), MgCl2(aq), CaCl2(aq), NaI(aq)). The results obtained were also used to calculate the Specific ion Interaction Theory (SIT) and Pitzer coefficients for the dependence on medium and ionic strength of glutathione species, as well as the formation constants of weak Mg j H i (GSH)(i+2j−3) and Ca j H i (GSH)(i+2j−3) complexes. Direct calorimetric titrations were also carried out in pure NaCl(aq) and in NaCl(aq)/CaCl2(aq) mixtures at different ionic strengths (0.25 ≤ I c /mol L−1 ≤ 5.0) in order to determine the enthalpy changes for the protonation and complex formation equilibria in these media at T = 298.15 K. Results obtained are useful for the definition of glutathione speciation in any aqueous media containing the main cations of natural waters and biological fluids, such as Na+, K+, Mg2+, and Ca2+. Finally, this kind of systematic studies, where a series of ionic media (e.g., all alkali metal chlorides) is taken into account in the determination of various thermodynamic parameters, is useful for the definition of some trends in the thermodynamic behavior of glutathione in aqueous solution.

Modeling the acid-base properties of glutathione in different ionic media, with particular reference to natural water and biological fluids

CIGALA, ROSALIA maria;CREA, Francesco;DE STEFANO, Concetta;LANDO, GABRIELE;MILEA, Demetrio;SAMMARTANO, Silvio
2012

Abstract

The acid–base properties of γ-l-glutamyl-l-cysteinyl-glycine (glutathione, GSH) were determined by potentiometry (ISE-H+, glass electrode) in pure NaI(aq) and in NaCl(aq)/MgCl2(aq), and NaCl(aq)/CaCl2(aq) mixtures, at T = 298.15 K and different ionic strengths (up to I c ~ 5.0 mol L−1). In addition, the activity coefficients of glutathione were also determined by the distribution method at the same temperature in various ionic media (LiCl(aq), NaCl(aq), KCl(aq), CsCl(aq), MgCl2(aq), CaCl2(aq), NaI(aq)). The results obtained were also used to calculate the Specific ion Interaction Theory (SIT) and Pitzer coefficients for the dependence on medium and ionic strength of glutathione species, as well as the formation constants of weak Mg j H i (GSH)(i+2j−3) and Ca j H i (GSH)(i+2j−3) complexes. Direct calorimetric titrations were also carried out in pure NaCl(aq) and in NaCl(aq)/CaCl2(aq) mixtures at different ionic strengths (0.25 ≤ I c /mol L−1 ≤ 5.0) in order to determine the enthalpy changes for the protonation and complex formation equilibria in these media at T = 298.15 K. Results obtained are useful for the definition of glutathione speciation in any aqueous media containing the main cations of natural waters and biological fluids, such as Na+, K+, Mg2+, and Ca2+. Finally, this kind of systematic studies, where a series of ionic media (e.g., all alkali metal chlorides) is taken into account in the determination of various thermodynamic parameters, is useful for the definition of some trends in the thermodynamic behavior of glutathione in aqueous solution.
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/1941187
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? 5
  • Scopus 40
  • ???jsp.display-item.citation.isi??? 37
social impact