Numerous studies have shown that Hg(II) binds
strongly to ligands with free mercapto groups. In biological
systems, the activity of intra- and extracellular
proteins and enzymes with free mercapto groups is
adversely affected by binding of the -SH groups to Hg-
(II). The tripeptide glutathione, which is found in
approximately millimolar concentrations in the erythrocytes
of whole blood, has several important functions.
One such function is to maintain the -SH groups in
certain proteins, which are essential for their activity,
in a reduced state by preventing the oxidation of the -SH
groups to disulfide groups. An understanding of the
nature and the extent of binding of glutathione to Hg(II)
is, therefore, of importance in seeking explanations for
the manifestation of the acute and chronic toxic effects
of Hg(II). Glutathione has been used as an antidote for
mercury poisoning, but without much success. A knowledge
of the magnitude of the formation constants of the
Hg(II)-glutathione complexes is essential for the development
of effective antidotes for mercury poisoning.
These formation constants are also important in understanding
the manner in which Hg(II) is mobilized and
transported in biological systems. There is a serious
problem, however, with the published value of the
formation constant of the 1:2 mercury(II)-glutathione
complex, HgL2, where L represents the completely deprotonated
glutathione molecule. All charges are omitted
from the ligand and the mercury complexes for the sake
of simplicity. There is also some inconsistency in the
published reports on the stoichiometry of the Hg(II)-
glutathione complexes that are formed at various pH
values and at various Hg(II):glutathione ratios. In a
pioneering polarographic investigation of the reaction
between Hg(II) and glutathione, Stricks and Kolthoff (1)
showed that the complexes HgL2, Hg2L2, and Hg3L2 were
formed in the pH range 3-9 in the absence of chloride
Numerous studies have shown that Hg(II) binds
strongly to ligands with free mercapto groups. In biological
systems, the activity of intra- and extracellular
proteins and enzymes with free mercapto groups is
adversely affected by binding of the -SH groups to Hg-
(II). The tripeptide glutathione, which is found in
approximately millimolar concentrations in the erythrocytes
of whole blood, has several important functions.
One such function is to maintain the -SH groups in
certain proteins, which are essential for their activity,
in a reduced state by preventing the oxidation of the -SH
groups to disulfide groups. An understanding of the
nature and the extent of binding of glutathione to Hg(II)
is, therefore, of importance in seeking explanations for
the manifestation of the acute and chronic toxic effects
of Hg(II). Glutathione has been used as an antidote for
mercury poisoning, but without much success. A knowledge
of the magnitude of the formation constants of the
Hg(II)-glutathione complexes is essential for the development
of effective antidotes for mercury poisoning.
These formation constants are also important in understanding
the manner in which Hg(II) is mobilized and
transported in biological systems. There is a serious
problem, however, with the published value of the
formation constant of the 1:2 mercury(II)-glutathione
complex, HgL2, where L represents the completely deprotonated
glutathione molecule. All charges are omitted
from the ligand and the mercury complexes for the sake
of simplicity. There is also some inconsistency in the
published reports on the stoichiometry of the Hg(II)-
glutathione complexes that are formed at various pH
values and at various Hg(II):glutathione ratios. In a
pioneering polarographic investigation of the reaction
between Hg(II) and glutathione, Stricks and Kolthoff (1)
showed that the complexes HgL2, Hg2L2, and Hg3L2 were
formed in the pH range 3-9 in the absence of chloride
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