The interaction between lanthanide ions and a polyfunctional ligand, glutathione, was studied with use of lanthanide-induced shifts. From the pH dependence of 13C chem. shifts, the pKa values of the carboxyl deprotonation at GSH glutamyl and glycyl terminals are evaluated to be 2.20 and 3.50, resp. GSH is coordinated to lanthanide ions independently through its two ionized terminal carboxyl groups, with complex stability constants of 12.5 and 100.0 L/mol at glutamyl and glycyl sites. An anal. of 13C shifts induced by heavy lanthanide ions from Dy3+ to Yb3+ indicates that the heavy lanthanide ions form isostructural complexes with GSH in aqueous solution and that both the glycyl and glutamyl carboxyl groups may be bidentately coordinated to lanthanides.

Key words: C13 NMR SPECTROMETRY, INDUCTION, RARE EARTH METAL COMPLEX, CHEMICAL SHIFT, GLUTATHIONE, DATA ANALYSIS