Dataset Information

Interaction of N-acetyl-l-cysteine with Na⁺, Ca²⁺, Mg²⁺ and Zn²⁺. Thermodynamic aspects, chemical speciation and sequestering ability in natural fluids.

ABSTRACT: The estimation of thermodynamic parameters of N-Acetyl-L-cysteine (NAC) protonation were determined in NaCl_(aq), (CH₃)₄NCl_(aq), (C₂H₅)₄NI_(aq), employing various temperature and ionic strengths conditions, by potentiometric measurements. The interaction of NAC with some essential metal cations (e.g., Ca²⁺, Mg²⁺ and Zn²⁺) was investigated as well at 298.15 K in NaCl_(aq) in the ionic strength range 0.1 ? I/mol dm^-3 ? 1.0. The values of protonation constants at infinite dilution and at T = 298.15 K are: log K ₁ ^H = 9.962 ± 0.005 (S-H) and log K ₂ ^H = 3.347 ± 0.008 (COO-H). In the presence of a background electrolyte, both log K ₁ ^H and log K ₂ ^H values followed the trend (C₂H₅)₄NI ? (CH₃)₄NCl ? NaCl. The differences in the values of protonation constants among the three ionic media were interpreted in terms of variation of activity coefficients and formation of weak complexes. Accordingly, the determination of the stability of 4 species, namely: NaL^-, NaHL⁰ _(aq), (CH₃)₄NL^-, (CH₃)₄NHL⁰ _(aq) was assessed. In addition, as regards the interactions of Mg²⁺, Ca²⁺ and Zn²⁺ with NAC, the main species where the ML⁰ _(aq), ML(OH)^-, and ML₂ ^2-, that were found to be important in the chemical speciation of NAC in real multicomponent solutions. The whole set of the data collected may be crucial for the development of NAC-based materials for natural fluids selective decontamination from heavy metals.

SUBMITTER: Bretti C

PROVIDER: S-EPMC7455796 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Interaction of N-acetyl-l-cysteine with Na+, Ca2+, Mg2+ and Zn2+. Thermodynamic aspects, chemical speciation and sequestering ability in natural fluids.

Bretti Clemente C Cardiano Paola P Irto Anna A Lando Gabriele G Milea Demetrio D Sammartano Silvio S

Journal of molecular liquids 20200829

The estimation of thermodynamic parameters of N-Acetyl-L-cysteine (NAC) protonation were determined in NaCl(aq), (CH3)4NCl(aq), (C2H5)4NI(aq), employing various temperature and ionic strengths conditions, by potentiometric measurements. The interaction of NAC with some essential metal cations (e.g., Ca2+, Mg2+ and Zn2+) was investigated as well at 298.15 K in NaCl( ...[more]

PMID: 32904480

Similar Datasets

Project description:β-N-methyl-amino-L-alanine (BMAA) in the presence of bicarbonate (HCO3-) undergoes structural modifications generating two carbamate species, α-carbamate and β-carbamate forms of BMAA. The chemical structure of BMAA and BMAA-carbamate adducts strongly suggest they may interact with divalent metal ions. The ability of BMAA to cross the blood-brain barrier and possibly interact with divalent metal ions may augment the neurotoxicity of these molecules. To understand the effects of divalent metal ions (Mg2+, Zn2+, and Cu2+) on the overall dynamic equilibrium between BMAA and its carbamate adducts, a systematic study using nuclear magnetic resonance (NMR) is presented. The chemical equilibria between BMAA, its carbamate adducts, and each of the divalent ions were studied using two-dimensional chemical exchange spectroscopy (EXSY). The NMR results demonstrate that BMAA preferentially interacts with Zn2+ and Cu2+, causing an overall reduction in the production of carbamate species by altering the dynamic equilibria. The NMR-based spectral changes due to the BMAA interaction with Cu2+ is more drastic than with the Zn2+, under the same stoichiometric ratios of BMAA and the individual divalent ions. However, the presence of Mg2+ does not significantly alter the dynamic equilibria between BMAA and its carbamate adducts. The NMR-based results are further validated using circular dichroism (CD) spectroscopy, observing the n ➔ π interaction in the complex formation of BMAA and the divalent metal ions, with additional verification of the interaction with Cu2+ using UV-Vis spectroscopy. Our results demonstrate that BMAA differentially interacts with divalent metal ions (Mg2+ < Zn2+ < Cu2+), and thus alters the rate of formation of carbamate products. The equilibria between BMAA, the bicarbonate ions, and the divalent metal ions may alter the total population of a specific form of BMAA-ion complex at physiological conditions and, therefore, add a level of complexity of the mechanisms by which BMAA acts as a neurotoxin.

Dataset Information

Interaction of N-acetyl-l-cysteine with Na⁺, Ca²⁺, Mg²⁺ and Zn²⁺. Thermodynamic aspects, chemical speciation and sequestering ability in natural fluids.

Publications

Interaction of N-acetyl-l-cysteine with Na<sup>+</sup>, Ca<sup>2+</sup>, Mg<sup>2+</sup> and Zn<sup>2+</sup>. Thermodynamic aspects, chemical speciation and sequestering ability in natural fluids.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure