The formation constants of the 1:1 and 1:2 complexes of Hg(II) with glutathione and their
protonated species have been determined by using a competitive potentiometric titration with
the competing ligand diethylenetriaminepentaacetic acid (DTPA). The formation constants
of the 1:1 complex and its protonated species have not been reported previously. The formation
constant of the 1:2 complex of Hg(II) and glutathione is substantially smaller than the accepted
value that has been reported in the literature. These results have important implications in
the models that have been employed to explain the mobilization and distribution of Hg(II) in
biological systems.