title: The binding sites of cadmium to a reduced form of glutathione.
abstract: Glutathione is the most abundant low molecular weight thiol-containing molecule in biological cells with a strong tendency to interact with metal ions. Among the eight possible glutathione binding sites, only two are determined as groups that interact with the Cd2+ ion. Analysis of vibrational spectra and 13C and 1H NMR spectra revealed that thiol and glutamyl's carboxylic groups are groups that cooperate in interaction with Cd2+ ions. The coordination of Cd2+ with those groups was supported by the application of auxiliary molecules (D-penicillamine, glycine, cysteine and glutamic acid dipeptides, mercaptosuccinic acid and N-acetyl-L-cysteine). These molecules provide a reliable assignment of the fundamental vibrations in the glutathione vibrational spectra. Concentration-dependent measurements of Cd2+ ions showed that the optimal stoichiometry of coordination with the glutathione molecule is 1:1. The analysis of 3J (Halpha, H(N)) coupling constants and conformational sensitive bands in the glutathione vibrational spectra suggest that interaction with Cd2+ ions significantly alters glutathione backbone conformation. The binding of ions induced the conformational change of the cysteine backbone from a predominantly beta structure to P(II).
authors.affiliation: National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia.
authors.forename: Martina
authors.initials: M
authors.lastname: Glusic
authors.forename: Polona
authors.initials: P
authors.lastname: Ropret
authors.forename: Katarina
authors.initials: K
authors.lastname: Vogel-Mikus
authors.forename: Joze
authors.initials: J
authors.lastname: Grdadolnik
mesh_terms: D001665:Binding Sites; D002104:Cadmium / Q000737:chemistry*; D005978:Glutathione / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010084:Oxidation-Reduction; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D002104:Cadmium; D005978:Glutathione