Behavior of glutathione as ligand of lead (II).

Emilio Bottari, Gaetano De Tommaso, Maria Rosa Festa, Mauro Iuliano, Giancarlo Zennaro

Journal: Chemosphere 2020;246():125718

PMID: 31918082

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Abstract

The presence and mobilization of toxic metal cations represents under many aspects a current and important problem in the environmental field. In this research, as cation lead (II) ion was studied. The formation of complexes between glutathione and lead (II) was studied at 25 °C and in 1.00 M NaCl as ionic medium by means of measurements of electromotive force (e.m.f.) of cells containing glass and lead amalgam electrodes. In the same experimental conditions, the protonation constants of glutathione were determined potentiometrically, using a cell containing the glass electrode. In the same experimental conditions, by considering glutathione (GSH) completely deprotonated, four protonation constants were determined. Potentiometric data could be explained by assuming the formation of 1:1 complexes between GSH and Pb and with the participation of hydrogen ions. The stability constants of the assumed complexes were determined. The 1:1 ratio between GSH and lead (II) was confirmed by spectrophotometric investigations. Measurements by Infrared Rays (IR) and protonic Nuclear Magnetic Resonance (H NMR) provide information on the structure of the found complexes.

Address: Chemistry Department, Roma University "La Sapienza", P.le A. Moro 5, 00185, Rome, Italy. Electronic address: [email protected].; Chemistry Sciences Department, Naples University "Federico II", Via Cintia, Monte Sant'angelo, 21 Naples, Italy. Electronic address: [email protected].; Chemistry Department, Roma University "La Sapienza", P.le A. Moro 5, 00185, Rome, Italy. Electronic address: [email protected].; Chemistry Sciences Department, Naples University "Federico II", Via Cintia, Monte Sant'angelo, 21 Naples, Italy. Electronic address: [email protected].; Chemistry Department, Roma University "La Sapienza", P.le A. Moro 5, 00185, Rome, Italy. Electronic address: [email protected].

DOI: 10.1016/j.chemosphere.2019.125718

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MeSH Terms: Cations, Glutathione, Hydrogen-Ion Concentration, Lead, Ligands, Magnetic Resonance Spectroscopy, Potentiometry, Protons, Spectrophotometry